//////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1072 SUBJECT: Possible burst from SGR1806-20 DATE: 01/06/26 23:21:40 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley, on behalf of the Ulysses GRB team, reports: In addition to observing the burst from SGR1806-20 on 2001 June 23 at 57293 s UT (GCN 1070), Ulysses observed a later event whose origin is likely to be this same SGR. This burst would have had an Earth-crossing time of 61056.8 s. Its duration was ~0.032 s, and its 25-100 keV fluence was ~2x10^-7 erg/cm^2. It had a peak flux over 0.032 s of ~6x10^-6 erg/cm^2 s. To our knowledge, no other instrument observed this event so we cannot be absolutely certain of its origin, but based on its time history and proximity in time to the previous burst, its origin is likely to be SGR1806-20, rather than SGR1900+14 (GCN 1071). //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1222 SUBJECT: IPN observations of SGR1806-20 DATE: 02/01/25 20:48:02 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley, on behalf of the Ulysses GRB team, and C. Guidorzi, E. Montanari, F. Frontera, and M. Feroci, on behalf of the BeppoSAX GRBM team, report: Ulysses and BeppoSAX have detected a series of short duration bursts which appear to originate from SGR1806-20: DATE TIME ULYSSES BEPPOSAX ____ ____ _______ ________ 020117 81678* YES IN SAA AND EARTH-BLOCKED 020118 71671 YES YES 020122 38418* YES NO DATA *TIME AT ULYSSES, WHICH WAS ABOUT 1250 LIGHT-SECONDS FROM EARTH; EARTH-CROSSING TIME FOR SGR1806 IS ABOUT 107 S LATER The only burst which could be triangulated was the one on January 18, and its position agrees with that of SGR1806-20. The burst on January 22 was particularly intense. If all of these events are indeed from SGR1806-20, this may signal a resurgence of activity from this source. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1233 SUBJECT: IPN detection of further activity from SGR1806-20 DATE: 02/01/29 00:34:27 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley, on behalf of the Ulysses GRB team, E. Mazets and S. Golenetskii, on behalf of the Konus-Wind GRB team, and C. Guidorzi, E. Montanari, F. Frontera, and M. Feroci, on behalf of the BeppoSAX GRBM team, report: The IPN continues to detect activity which is probably from SGR1806-20. The updated event list is now: DATE TIME ULYSSES BEPPOSAX KONUS ____ ____ _______ ________ _____ 020117 81788 YES IN SAA WEAK RESPONSE 020118 71671 YES YES YES 020122 38499 YES NO DATA YES 020124 79251* YES 020125 36444* YES *TIME AT ULYSSES, WHICH WAS ABOUT 1250 LIGHT-SECONDS FROM EARTH; EARTH-CROSSING TIME FOR SGR1806 IS ABOUT 75 S LATER The bursts on the 17th, 18th, and 22nd have all been triangulated to annuli which are consistent with the position of SGR1806. The bursts on the 24th and 25th are definitely SGR-like, in that their durations are ~30 ms; there are too few photons in the Ulysses data to determine their spectra, however. We are searching for confirmation of them in the GRBM and KONUS data, which will allow triangulation. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1391 SUBJECT: IPN triangulation of a burst from SGR1806-20 DATE: 02/05/16 00:18:36 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley, on behalf of the Ulysses GRB team, and D. Smith, R. Lin, J. McTiernan, R. Schwartz, C. Wigger, W. Hajdas, and A. Zehnder, on behalf of the RHESSI GRB team, report: Ulysses and RHESSI observed a burst on May 15 at 01:26:41 UT with ~20 ms duration. Triangulation gives an annulus which is consistent with the position of SGR1806-20. Ulysses has in addition observed numerous short events over the past several days. Although none could be triangulated, this may suggest that SGR1806-20 is entering a new period of activity. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1396 SUBJECT: IPN detection of possible bursts from SGR1806-20 DATE: 02/05/27 23:19:13 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley, on behalf of the Ulysses GRB team, E. Mazets and S. Golenetskii, on behalf of the Konus-Wind GRB team, and T. Cline, on behalf of the Ulysses and Konus teams, report: Two short bursts were detected on May 25 which, due to their proximity in time to an earlier burst from SGR1806-20 (see GCN 1391), may also be from this SGR. The first was at ~16014 s and was observed by Konus-Wind; the second was detected by Ulysses and was at 43615 s (Ulysses time; the spacecraft was ~1850 light-seconds from Earth). If the second event came from SGR1806-20, its Earth-crossing time would have been ~1047 s earlier, or ~42568 s. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1726 SUBJECT: IPN detection of renewed activity from SGR1806-20 DATE: 02/12/07 20:31:06 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley, on behalf of the Ulysses GRB team, E. Mazets and S. Golenetskii, on behalf of the Konus-Wind GRB team, and T. Cline, on behalf of the Ulysses and Konus GRB teams, report: Ulysses has observed 5 short, intense SGR-like bursts on December 5 and 6. So far, one of these events has also been reported by Konus-Wind, and the center line of its triangulation annulus passes ~10" from the position of SGR1806-20, and >5 degrees from that of SGR1900+14. We conclude that this burst indeed originates from SGR1806-20. As there is a hint of continuing activity from SGR1900+14, we cannot at this point be certain of the origin of the other events, but will attempt to determine this as soon as possible. The times of these events were: December 5, 2002: 02828 s * 12925 s * 32992 s ** 72064 s * December 6, 2002: 63291 s * * crossing time at Ulysses; subtract ~418 s to get Earth-crossing time if the source was SGR1806-20 ** event also observed by Konus; this is the Earth-crossing time //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1764 SUBJECT: IPN detection of continued activity from SGR1806-20 DATE: 02/12/17 21:58:18 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley and T. Cline, on behalf of the Ulysses GRB team, and V. Pal'shin, E. Mazets, and S. Golenetskii, on behalf of the Helicon- Coronas GRB team, report: Ulysses and Helicon observed this burst at 40754 seconds. As observed by Ulysses, it had a duration of approximately 0.25 seconds, a 25-100 keV fluence of approximately 6.4E-06 erg/cm2, and a peak flux of approximately 7.4E-06 erg/cm2 s over 0.25 seconds. We have triangulated it to a preliminary annulus centered at RA, Decl(2000)= 3.003, -36.081 degrees, whose radius is 78.796 +/- 0.034 degrees (3 sigma ). As the center line of this annulus passes within 14" of the position of SGR1806-20, we conclude that it was the source of this burst. Prior to this, the last confirmed burst from this SGR was on December 5 (GCN 1726). //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2283 SUBJECT: HETE detection of burst from SGR1806-20 DATE: 03/06/16 18:22:18 GMT FROM: Roland Vanderspek at MIT K. Hurley, J-L. Atteia, N. Kawai, D. Lamb, G. Ricker, and S. Woosley on behalf of the HETE Science Team; C. Barraud, M. Boer, J-F Olive, and J-P Dezalay on behalf of the HETE FREGATE Team; N. Butler, G. Crew, J. Doty, G. Prigozhin, R. Vanderspek, J. Villasenor, T. Cline, J. G. Jernigan, A. Levine, F. Martel, E. Morgan, G. Monnelly, G. Azzibrouck, J. Braga, R. Manchanda, and G. Pizzichini, on behalf of the HETE Operations and HETE Optical-SXC Teams; M. Suzuki, C. Graziani, Y. Shirasaki, T. Donaghy, M. Matsuoka, K. Torii, T. Tamagawa, T. Sakamoto, A. Yoshida, E. Fenimore, M. Galassi, Y. Nakagawa, R. Satoh, Y. Urata, T. Yamazaki and Y. Yamamoto, on behalf of the HETE WXM Team report: HETE Trigger H2734, detected at 04:14:29 UT on 9 June 2003, was due to a short burst from SGR1806-20. This burst had a duration of ~100 ms and a 30-100 keV fluence of 6 x 10^-8 erg/cm2. The position was not circulated automatically because the spacecraft aspect had not yet been determined. This detection may indicate the onset of a new period of activity for this SGR. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2297 SUBJECT: IPN detection of renewed activity from SGR1806-20 DATE: 03/07/14 18:51:10 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley and T. Cline, on behalf of the Ulysses and HETE GRB teams, D. M. Smith, R. P. Lin, J. McTiernan, R. Schwartz, C. Wigger, W. Hajdas, and A. Zehnder, on behalf of the RHESSI GRB team, A. von Kienlin, G. Lichti, and A. Rau, on behalf of the INTEGRAL SPI-ACS GRB team, and G. Ricker, J-L Atteia, N. Kawai, D. Lamb, S. Woosley, J. Doty, R. Vanderspek, J. Villasenor, G. Crew, G. Monnelly, N. Butler, J.G. Jernigan, A. Levine, F. Martel, E. Morgan, G. Prigozhin, J. Braga, R. Manchanda, G. Pizzichini, Y. Shirasaki, C. Graziani, M. Matsuoka, T. Tamagawa, K. Torii, T. Sakamoto, A. Yoshida, E. Fenimore, M. Galassi, T. Tavenner, T. Donaghy, M. Boer, J-F Olive, and J-P Dezalay, on behalf of the HETE GRB team, report: Ulysses, INTEGRAL (SPI-ACS), RHESSI, and HETE have observed two events whose arrival directions are consistent with that of SGR1806-20: DATE UT ANNULUS ANNULUS ANNULUS deltaR DISTANCE DURATION PEAK FLUX FLUENCE SPACECRAFT S. RA(2000) DEC(2000) RADIUS (3 SIGMA) DEG. S. erg/cm2s erg/cm2 030712 76693.0 335.440 -27.794 57.625 0.017 0.003 0.180 5E-6 4E-6 ULYSSES, RHESSI, INTEGRAL 030713 77470.8 335.566 -27.667 57.749 0.017 0.0001 0.032 1E-6 1E-7 ULYSSES, HETE(2763) The annulus half-width is deltaR; distance is the angular distance between the centerline of the annulus and the position of SGR1806-20; duration is the duration as observed by Ulysses; peak fluxes and fluences are as observed by Ulysses, and are over 0.03125 s, and 25-100 keV. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2306 SUBJECT: RXTE PCA Observations of SGR1806-20 Region DATE: 03/07/18 02:53:20 GMT FROM: Craig Markwardt at GSFC RXTE PCA Observations of SGR 1806-20 Region A. Ibrahim (GWU/GSFC), C. Markwardt (UMD/GSFC), J. Swank (GSFC), K. Hurley (UCB), T. Cline (GSFC), & W. Parke (GWU) Report: In response to the burst activity reported by IPN on Jul 14 (GCN 2297), we pointed the RXTE PCA at the position of SGR 1806-20 on Jul 15, 11:35-12:20 UT. A 0.4 mCrab pulsed flux was detected with a period of 5.54 s +/- 0.01 s. The PCA saw 3.5 mCrab total flux, but as much as half is due to Galactic ridge emission in the field of view, so that the pulsed fraction could exceed 20%. The large difference between the pulse period and the last observed pulse period of SGR 1806-20 (Woods et al. 2002, ApJ, 576, 381) suggests that a new pulsar is present. There are no known pulsars with that period in the 1.2 deg radius field of view of the PCA and we can rule out the nearby candidate SGR 1801-23 (Cline et al. 2000, ApJ, 531, 407). If the new pulsar were responsible for the recent bursts, there would be three SGRs in a small region. However it is possible that both SGR 1806-20 and another pulsar are active simultaneously. PCA scanning observations are planned. This message is citeable. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2309 SUBJECT: SGR 1806-20, submm observations DATE: 03/07/19 05:22:38 GMT FROM: Sylvio Klose at TLS Tautenburg S. Klose (@SEST), B. Stecklum, & H. Linz, Thuringer Landessternwarte Tautenburg, J. Greiner, MPE Garching, report: We observed the field of SGR 1806-20 with the Swedish-ESO Submillimetre Telescope (SEST) at La Silla, Chile, on July 18/19, 0:35 - 2:10 UT. The observations were performed with the SIMBA Imaging Bolometer Array at a wavelength of 1.2mm and started approximately 45 min after an outburst was recorded from SGR 1806 by HETE 2 and ended approximately 1.5 hrs before the next outburst was recorded (Hurley et al., GCN 2308). A superposition of 4 maps (400 x 600 arcsec), 8 min mapping time each, does not reveal any source at the position of the SGR down to a flux density limit of approximately 100 mJy. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2311 SUBJECT: Konus-Wind detection of the bursts from SGR1806-20 region DATE: 03/07/22 13:47:11 GMT FROM: Dmitry Frederiks at Ioffe Institute S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks (all Ioffe Institute), T. Cline (NASA GSFC), and K.Hurley (UCB) on behalf of the Konus-Wind team, report: A short soft burst was detected on 030719 by Konus-Wind starting at 83914.490s UT. The event had a duration of 0.25s, a soft energy spectrum ~ E^(-1)exp(-E/Eo) with Eo = 18.5 +/- 1 keV, fluence of 5x10-6 erg sm-2 and peak flux of 3x10-5 erg cm-2 s-1, evaluated both in 15-300 keV range. Apparently the burst originates from the SGR1806-20 or from its close vicinity in accordance with observations of the burst activity reported in GCN 2306, 2307, and 2308. Two weak soft events were detected by Konus-Wind in the background mode on 030720 at 08:07:12 and 22:34:19. The last event was detected by HETE (H2773). Estimated time delay is consistent with SGR1806-20 position. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2354 SUBJECT: IPN detection of continued activity from SGR1806-20 DATE: 03/08/18 23:28:52 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley and T. Cline, on behalf of the Ulysses and Mars Odyssey GRB teams, I. Mitrofanov, S. Charyshnikov, V. Grinkov, A. Kozyrev, M. Litvak, and A. Sanin, on behalf of the HEND-Odyssey GRB team, and W. Boynton, C. Fellows, K. Harshman, C. Shinohara and R. Starr, on behalf of the GRS-Odyssey GRB team, report: Ulysses and Mars Odyssey (HEND) observed this unusually long SGR burst. As observed by Ulysses, it had a duration of approximately 1 second, a 25-100 keV fluence of approximately 7.3E-06 erg/cm2, and a peak flux of approximately 1.9E-05 erg/cm2 s over 0.25 seconds. We have triangulated it to a preliminary annulus centered at RA, Decl(2000)=340.644, -22.919 degrees, whose radius is 63.096 +/-0.013 degrees (3 sigma). As the center line of this annulus passes 0.003 degrees from the position of SGR1806-20, we consider it most likely that this event originated from that SGR. If so, the Earth-crossing time was 50231 seconds. However, due to the present configuration of the IPN, Ulysses/Mars, Mars/Earth, and Ulysses/Earth annuli which are consistent with the position of SGR1806-20 will also be consistent with portions of the error circle for the possible new SGR, 1808-20 (GCN 2351). Depending on the exact position of SGR1808-20, however, the converse is not necessarily true. Thus it may be possible to confirm the existence of this new source with the IPN if it bursts again. The situation is illustrated with a map which has been posted at ssl.berkeley.edu/ipn3/030818. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2372 SUBJECT: INTEGRAL ToO OBSERVATIONS OF SGR1806-20: CALL FOR CORRELATED OBSERVATIONS DATE: 03/08/29 22:10:44 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley and D. Hartmann, on behalf of a large collaboration, report: A 240 ksec INTEGRAL target of opportunity observation of SGR1806-20 has been scheduled for 2003 September 03, starting at 22:45 UT. Simultaneous observations at all wavelengths, but particularly in the NIR (bearing in mind that the reddening is AV=29 mag), are encouraged. The best position for this SGR is the one obtained by Chandra (Eikenberry et al., ApJ 563, L133, 2001; Kaplan et al., ApJ 564, 935, 2002): RA(2000)=18 h 08 m 39.32 s, Decl(2000)=-20 o 24 ' 39.5 " Updates to the INTEGRAL schedule will be posted at: http://astro.estec.esa.nl/integral_webapps/index.jsp?future //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2376 SUBJECT: Radio Observations of SGR1806-20 DATE: 03/09/04 15:41:11 GMT FROM: Dale A. Frail at NRAO M. P. Rupen and D. A. Frail (NRAO) report on behalf of a larger collaboration: "Using the VLA at 8.5 GHz we imaged a 60-arcsec region centered on the Chandra position for SGR 1806-20 (Kaplan et al., ApJ 564, 935, 2002). This short 9 min integration was made on 2003 September 3.15 UT, concurrent with a planned 240 ksec INTEGRAL target of opportunity observation (GCN#2372). No radio source was detected at or near this position. The rms noise was 55 microJy/beam, for a beam size of 450 x 240 mas (p.a. 12 degrees). The min/max within the Chandra ±0.3 arcsec error circle were (-121,+153) microJy/beam. No further observations are planned." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2377 SUBJECT: IBAS detection of bursts from SGR 1806-20 DATE: 03/09/04 16:49:09 GMT FROM: Sandro Mereghetti at IASF/CNR S.Mereghetti (IASF, Milano), D.Gotz (IASF, Milano) for the ISDC IBAS Localization Team and K.Hurley, on behalf of the INTEGRAL SGR TOO collaboration, report During INTEGRAL TOO observations of the region of SGR 1806-20, performed from 2003 September 3 22:45 UT to September 4 02:54 UT, two bursts have been detected and localized by IBAS. The first burst occurred on September 4 at 00:53:43.9 UT at coordinates R.A. = 18 08 43.6 Dec.= -20 23 28 (J2000). The second one occurred at 01:15:56.9 UT at coordinates R.A. = 18 08 34.3 Dec.= -20 26 25. These localizations have an uncertainty of about 3 arcmin. Therefore the bursts can be confidently associated with SGR 1806-20 and not with SGR 1808-20 (GCN 2351). Both bursts were detected with IBIS/ISGRI in the 15-100 keV range and had a duration of about 200 ms. Their fluences in the 25-100 keV range were about 2x10-9 ergs cm-2 and 2x10-8 ergs cm-2. The TOO INTEGRAL observation of this region (GCN 2372) will continue until September 7 at 03:05 UT. Continued ground-based observations of this region are encouraged. This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2408 SUBJECT: A burst from SGR 1806-20 detected with IBAS DATE: 03/10/07 08:19:08 GMT FROM: Diego Gotz at IASF-CNR D.Gotz (IASF, Milano), S. Mereghetti (IASF, Milano) and M. Beck (ISDC) for the ISDC IBAS Localization Team and F. Mirabel (CEA, Saclay) and the INTEGRAL Science Working Team report During INTEGRAL Galactic Center Deep Exposure a burst originating from SGR 1806-20 has been detected and localized with IBAS at 18:51:27.41 on October 6 2003. The burst was detected with IBIS/ISGRI in the 15-100 keV range and has a duration of about 60 ms. The fluence in the 25-100 keV energy band is about 3x10-8 ergs cm-2. This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2414 SUBJECT: IPN detection of continued activity from SGR1806-20 DATE: 03/10/09 00:02:33 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley and T. Cline, on behalf of the Ulysses and Konus GRB teams, and E. Mazets and S. Golenetskii, on behalf of the Konus-Wind GRB team, report: Ulysses and Konus-Wind observed this event at 12424 seconds on October 08. As observed by Ulysses, it had a duration of approximately 0.1 seconds, a 25-100 keV fluence of approximately 1.2E-06 erg/cm2, and a peak flux of approximately 1.8E-05 erg/cm2 s over 0.03125 seconds. It was followed approximately 50 seconds later by a second event with roughly one-third the intensity. We have triangulated it to a preliminary annulus centered at RA, Decl(2000)= 347.828, -18.495 degrees, whose radius is 70.687 +/- 0.010 degrees (3 sigma). The center line of this annulus passes 0.001 degrees from the position of SGR1806-20, and 0.117 degrees from the position of the AXP XTE J1810-197, excluding the latter as a possible source. This burst probably originated from SGR1806-20, but we note that the annulus also intersects the error circle of the possible new SGR1808-20. This localization may be improved. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2415 SUBJECT: SGR 1806-20 bursts with INTEGRAL and IBAS announcement on Soft Gamma-Ray Repeaters DATE: 03/10/09 08:29:46 GMT FROM: Sandro Mereghetti at IASF/CNR S. Mereghetti, D.Gotz (IASF, Milano) and M. Beck (ISDC) for the ISDC IBAS Localization Team, F. Mirabel (CEA, Saclay) and the INTEGRAL Science Working Team report: During INTEGRAL Core Program observations of the Galactic Center region, IBAS has detected several bursts from SGR 1806-20. They are summarized in the following Table. The positions derived by IBAS with typical errors smaller than 3 arcmin confirm that all of them originated from SGR 1806-20 and not from the nearby sources SGR 1808-20 (GCN 2351) or XTE J1810-197 (IAUC 8168, IAUC 8190). The bursts were detected with the IBIS/ISGRI instrument in the 15-100 keV energy range. Date October 2003 25-100 keV Fluence Duration Day UT (erg cm-2) (s) 6 18:51:27.4 3 x 10-8 0.06 GCN 2408 8 03:27:03.9 4 x 10-7 0.2 (*) 8 03:27:56.1 3 x 10-7 0.2 (*) 8 20:22:06.5 4 x 10-8 0.1 (*) IPN observations of this burst have been reported (GCN 2414) In the near future IBAS will start to distribute automatic Alert Packets for SGR bursts detected with high significance. This will allow rapid follow-up observations at other wavelengths. The source coordinates in the Alert Packets will allow IBAS users to distinguish such events from classical GRBs. This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2419 SUBJECT: Ongoing Bursting Activity from SGR 1806-20 detected with IBAS DATE: 03/10/15 12:46:32 GMT FROM: Diego Gotz at IASF-CNR D. Gotz, S. Mereghetti (IASF, Milano) and M. Beck (ISDC) for the ISDC IBAS Localization Team, F. Mirabel (CEA, Saclay) and the INTEGRAL Science Working Team report: Several more bursts from SGR 1806-20 have been detected by IBAS during INTEGRAL Core Program Galactic Center Deep Exposure. Their times, preliminary fluences and durations are summarized in the following table. The positions of the bursts are all consistent with SGR 1806-20 within 2 arcmin. The bursts were detected with the IBIS/ISGRI instrument in the 15-100 keV energy range. Date October 2003 25-100 keV Fluence Duration Day UT (erg cm-2) (s) 11 01:26:27.07 1.0 x 10-8 0.1 14 14:31:45.41 2.0 x 10-8 0.1 15 02:35:19.66 2.0 x 10-8 0.1 15 04:55:00.88 2.0 x 10-7 0.18 15 07:37:47.57 3.0 x 10-8 0.1 (*) 15 07:55:52.97 1.5 x 10-8 0.1 15 07:56:21.07 1.0 x 10-8 2 x 0.1 (**) 15 10:19:31.94 4.0 x 10-8 0.13 15 11:00:28.77 4.0 x 10-8 0.15 15 11:17:05.32 2.0 x 10-8 0.2 (*) This burst is preceeded by a small precursor lasting ~0.05 s (**) This burst consists of two distinct peaks, lasting ~0.1 s each, separated by ~0.2 s. The fluence given is for the first one. The second is has a smaller peak flux, but is harder. This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2451 SUBJECT: IPN detection of activity from SGR1806-20 DATE: 03/11/18 18:02:21 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley and T. Cline, on behalf of the Ulysses, Konus, and Mars Odyssey GRB teams, E. Mazets and S. Golenetskii, on behalf of the Konus-Wind GRB team, I. Mitrofanov, S. Charyshnikov, V. Grinkov, A. Kozyrev, M. Litvak, and A. Sanin, on behalf of the HEND-Odyssey GRB team, and W. Boynton, C. Fellows, K. Harshman, C. Shinohara and R. Starr, on behalf of the GRS/Odyssey GRB team, report: Konus-Wind and Mars Odyssey-HEND observed this GRB at 26660 seconds on 14 November 2003. As observed by Konus, it had a duration of approximately 1.4 seconds, an 18-200 keV fluence of approximately 3.6E+-05 erg/cm2, and a peak flux of approximately 6.3E-05 erg/cm2 s. We have triangulated it to a preliminary annulus centered at RA, Decl (2000) = 344.192, -8.447 degrees, whose radius is 70.299 +/- 0.036 degrees (3 sigma). As the center line of this annulus passes 0.009 degrees from the position of SGR1806-20, and 0.092 degrees from the center of the error circle of SGR1808-20, we conclude that the origin of this burst was most likely SGR1806-20. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2504 SUBJECT: IPN triangulation of an intermediate burst from SGR1806-20 DATE: 04/01/01 21:01:07 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley and T. Cline, on behalf of the Ulysses, Mars Odyssey, and Konus GRB teams, S. Golenetskii, E. Mazets, V. Pal'shin, and D. Frederiks on behalf of the Konus-Wind and Helicon/Coronas-F teams, I. Mitrofanov, S. Charyshnikov, V. Grinkov, A. Kozyrev, M. Litvak, and A. Sanin, on behalf of the HEND-Odyssey GRB team, W. Boynton, C. Fellows, K. Harshman, C. Shinohara and R. Starr, on behalf of the GRS-Odyssey GRB team, and D. M. Smith, R. P. Lin, J. McTiernan, R. Schwartz, C. Wigger, W. Hajdas, and A. Zehnder, on behalf of the RHESSI GRB team, report: Konus-Wind, Helicon, Mars Odyssey - HEND, and RHESSI observed this burst at 60913 s on 28 December 2003. As observed by Konus, its duration was 1.1s, its 15-200 keV fluence was 3x10^(-5) erg/cm2, and its peak flux was 8.6x10^(-5) erg/cm2 s. It had a soft spectrum, with kT=20 keV. Using Konus and Odyssey data, we have triangulated it to a preliminary annulus centered at RA, Decl(2000)=186.046, -2.629 degrees, whose radius is 85.436 +/- 0.028 degrees (3 sigma). As the centerline of this annulus passes 0.011 degrees from the position of SGR1806-20, we believe that this event is an intermediate burst from that source. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2541 SUBJECT: INTEGRAL detection of activity from SGR1806-20 DATE: 04/03/09 11:03:32 GMT FROM: Sandro Mereghetti at IASF/CNR S Mereghetti, D.Gotz, M. Beck and J.Borkowski on behalf of the IBAS Localization Team, S.Shaw and K.Pottschmidt on behalf of the INTEGRAL Science Data Centre and F.Mirabel on behalf the INTEGRAL Science Working Team report: The IBAS alert n.1563 corresponds to a short burst (0.2 seconds) with preliminary position within 1 arcminutes from the soft gamma-ray repeater SGR1806-20. Further off-line data analysis is in progress. This message is citeable. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2542 SUBJECT: IBAS results on a burst from SGR1806-20 DATE: 04/03/09 11:50:46 GMT FROM: Sandro Mereghetti at IASF/CNR D. Gotz, S. Mereghetti (IASF, Milano) for the ISDC IBAS Localization Team, F. Mirabel (CEA, Saclay) and the INTEGRAL Science Working Team report: We confirm that the burst of IBAS alert n.1563 (GCN 2541) originated from SGR1806-20. The burst was detected with the IBIS/ISGRI instrument in the 15-100 keV energy range, during the INTEGRAL Core Program Galactic Center Deep Exposure, at 10:24:08.35 UT of March 9. The preliminary estimate of the burst fluence in the 15-100 keV energy range is 2.2 x 10-7 erg cm-2. We remind that IBAS is also distributing real time Alert Packets for bursts from known SGR positions (see ISDC Newsletter n. 14 http://isdc.unige.ch/Newsletter/N/#ibas and GCN 2415). SGR 1806-20 will be in the INTEGRAL field of view for various time intervals in the next few days, thus possibly giving rise to other IBAS alerts. This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2558 SUBJECT: Summary of recent bursts from SGR 1806-20 detected by INTEGRAL DATE: 04/03/31 15:13:38 GMT FROM: Diego Gotz at IASF-CNR D. Gotz, S. Mereghetti (IASF, Milano), M. Beck (ISDC) on behalf of the IBAS Localization Team, N. Mowlavi and S. Shaw on behalf of the INTEGRAL Science Data Centre and the INTEGRAL Science Working Team report: SGR 1806-20 has been moderately active after the burst of March 9 (Gotz et al. GCN 2542). The times of the bursts discovered with IBAS in the IBIS/ISGRI data are the following: Start time (UT) IBAS Alert Number -------------------------------------------------- 2004-03-09T10:24:08.35 1563 (GCN 2541, 2542) 2004-03-16T13:02:06.43 1677 2004-03-20T06:34:35.05 1685 2004-03-20T17:57:01.83 * 2004-03-29T06:15:40.97 * 2004-03-29T11:46:47.50 * 2004-03-30T17:03:05.81 1716,1717 (*) These bursts have been detected with significance below the threshold for automatic delivery of IBAS Alert Packets The burst of March 30 was among the brightest detected by INTEGRAL from this Soft Gamma-Ray Repeater. It consisted of a main peak lasting about 0.11 s, followed by a smaller peak 0.1 s later. The fluence of the main peak was about 3 x 10-7 erg cm-2 (15-100 keV). This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2603 SUBJECT: IPN triangulation of an intense intermediate burst from SGR1806-20 DATE: 04/05/21 20:13:06 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley and T. Cline, on behalf of the Ulysses and Konus GRB teams, E. Mazets and S. Golenetskii, on behalf of the Konus-Wind GRB team, and D. M. Smith, R. P. Lin, J. McTiernan, R. Schwartz, C. Wigger, W. Hajdas, and A. Zehnder, on behalf of the RHESSI GRB team, report: Konus and RHESSI observed this soft-spectrum burst at 72247 s on May 19 2004. Ulysses was off. Its duration was 1.3 s, its fluence was ~2.8 x 10^-5 erg/cm^2, and its peak flux was ~3.3 x 10^-5 erg/cm^2 s. We have triangulated it to an annulus centered at RA, Decl(2000)=250.249, -19.744 degrees, whose radius is 20.792 +/- 2.019 degrees. As the center line of this annulus passes only 0.2 degrees from the position of SGR1806-20, we believe that it is the source of this event. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2604 SUBJECT: Activivty of SGR 1806-20 DATE: 04/05/28 13:46:43 GMT FROM: Dmitry Frederiks at Ioffe Institute S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks on behalf of Konus-Wind and Helicon/Coronas-F teams, T. Cline on behalf of the Konus-Wind team, and A. Rau, A. von Kienlin, G. Lichti on behalf of the INTEGRAL SPI-ACS GRB team report: Recently, Konus-Wind has detected seven SGR-like bursts in the trigger mode: Date Time, Duration, Fluence, Peak Flux, kT**** s UT s (20-200 keV) (20-200 keV) keV ergs/cm2 ergs/cm2 s ----------------------------------------------------------------------- 040427 47089.452 0.176 (3.43 +/- 0.07)E-6 (2.58 +/- 0.22)E-5 19+/-3 040519* 72250.485 1.376 (2.74 +/- 0.02)E-5 (3.19 +/- 0.09)E-5 21+/-2 040522** 31696.702 0.176 (2.16 +/- 0.06)E-6 (2.82 +/- 0.17)E-5 16+/-5 040522 45772.875 0.136 (1.33 +/- 0.04)E-6 (1.59 +/- 0.12)E-5 25+/-6 040523 50502.964 0.552 (4.32 +/- 0.09)E-6 (2.94 +/- 0.14)E-5 16+/-5 040525*** 12976.933 0.592 (8.74 +/- 0.12)E-6 (3.06 +/- 0.11)E-5 23+/-4 040526 29173.030 0.752 (5.88 +/- 0.11)E-6 (1.41 +/- 0.09)E-5 16+/-5 ------------------------------------------------------------------------ * - this burst was localized, the most like source of the burst is SGR 1806-20 (GCN 2603). ** - this burst was also detected by Helicon-Coronas-F in the background mode. Estimated time delay is consistent with SGR 1806-20 position. *** - this burst was also detected by INTEGRAL SPI-ACS. We have triangulated it to an annulus centered at RA(2000) = 259.389 deg, Decl(2000) = -17.958 deg, whose radius is 12.616 +/- 1.770 deg (3 sigma). The center line of this annulus passes 0.4 degrees from the position of SGR 1806-20. **** - the last column contains the values of spectral parameter kT for the OTTB spectral model: dN/dE ~ E^{-1} exp(-E/kT) Additionally, a number of SGR-like bursts (short and soft) were detected by both Konus detectors S1 and S2 in the background mode: Date Time, s UT (hh:mm:ss) --------------------------- 040519 25976 (07:12:56) 040519 86378 (23:59:38) 040520 44823 (12:27:03) 040522 2693 (00:44:53) 040522 30582 (08:29:42) 040522 80762 (22:26:02) 040522 83738 (23:15:38) 040523 18673 (05:11:13) 040523 39091 (10:51:31) 040523 40937 (11:22:17) 040523 65789 (18:16:29) The Konus ecliptic latitude response indicates that the source of the bursts is near ecliptic plane. All these data lead to the supposal that the all these bursts originated from SGR 1806-20, which, hereby, has entered a new phase of activity in the hard X-ray. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2607 SUBJECT: SGR 1806-20, potential NIR counterpart DATE: 04/06/08 11:56:28 GMT FROM: Sylvio Klose at TLS Tautenburg C. Kouveliotou (NASA/MSFC), S. Klose (Thuringer Landessternwarte Tautenburg), S. Wachter (Spitzer Science Center), P. Woods (USRA, NASA/MSFC), S. Patel (USRA, NASA/MSFC), J. Greiner (MPE Garching), B. Stecklum (Thuringer Landessternwarte Tautenburg), and M. van der Klis (University of Amsterdam) report: Following the recent activiation in X-rays of SGR 1806-20, we triggered a Target of Opportunity Observation of the source at ESO with VLT/ISAAC. Observations were performed in the Ks band on May 28, 6:24 UT - 6:50 UT. Altogether 14 images were taken, 1 min integrated exposure time each. For the final data analysis we used those images with the best seeing (8 of the 14 images). Within the 0.7 arcsec Chandra error circle as reported by Eikenberry et al. (ApJ 563, L133; their figure 3d), we identify an isolated point source with Ks = 19.6 +/- 0.4. This source might match the position of source 'B' in Eikenberry et al., while their source 'A', which is at the edge of the Chandra error circle, is resolved into at least two components. We tentatively identify either object B or the second component of object A as the potential K-band counterpart of SGR 1806-20. However, further observations are needed during quiescence of the SGR to determine whether one of the two sources is variable in order to firmly establish a connection with SGR 1806-20. We are deebly indebted the ESO staff at Paranal, in particular Poshak Gandhi, for performing the observations. This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2609 SUBJECT: SGR 1806-20: no IR variability of the proposed counterparts DATE: 04/06/09 17:33:11 GMT FROM: Stefano Covino at Brera Astronomical Observatory G.L. Israel, R. Mignani, S. Covino, S. Campana, L. Stella, N. Rea, V. Testa, G. Marconi on behalf of a larger team report: We have imaged in J, H and Ks bands with VLT/NACO the field of SGR 1806-20 on March 9th, 10th, 16th and 17th 2004. Observations were activated after the X-ray burst that occurred on March 9th (Mereghetti et al., GCN 2541). We have detected several sources within the Chandra error circle reported in Eikenberry et al. 2001 (ApJ 563, L133) including those reported in GCN 2607 (Kouveliotou et al.). The monitoring of these objects did not show any variability more significant than 2sigma in the Ks band on time scales from hours up to days. The limiting Ks magnitude was about 21.5. Both the lack of IR variability correlated to the X-ray burst activity and the relatively high IR flux for the proposed counterparts (GCN 2607) suggest that these objects are unlikely the IR counterpart to SGR 1806-20. This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2633 SUBJECT: Ongoing activity of SGR 1806-20 DATE: 04/07/29 17:31:04 GMT FROM: Dmitry Frederiks at Ioffe Institute S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks on behalf of Konus-Wind and Helicon/Coronas-F teams, T. Cline on behalf of the Konus-Wind team, and A. Rau, A. von Kienlin, G. Lichti on behalf of the INTEGRAL SPI-ACS GRB team report: Since last SGR burst 040615, listed in GCN 2611, Konus-Wind has detected seven SGR-like bursts in the trigger mode: Date Time, Duration, Fluence, Peak Flux, kT* s UT s (20-200 keV) (20-200 keV) keV ergs/cm2 ergs/cm2 s ----------------------------------------------------------------------- 040617 48377.157 0.104 (1.16 +/- 0.04)E-6 (2.28 +/- 0.14)E-5 23+/-3 040622 70209.587 0.332 (5.49 +/- 0.09)E-6 (3.59 +/- 0.18)E-5 17+/-1 040623 81361.257 0.440 (2.49 +/- 0.07)E-6 (1.74 +/- 0.13)E-5 17+/-2 040707 17546.478 0.696 (7.65 +/- 0.12)E-6 (1.86 +/- 0.10)E-5 18+/-1 040719 45188.316 0.264 (3.81 +/- 0.07)E-6 (2.44 +/- 0.21)E-5 20+/-2 040723 42259.178 0.192 (7.51 +/- 0.11)E-6 (5.63 +/- 0.19)E-5 20+/-1 040728 544.709 0.328 (4.36 +/- 0.09)E-6 (2.64 +/- 0.13)E-5 15+/-2 ------------------------------------------------------------------------ * - the last column contains the values of spectral parameter kT for the OTTB spectral model: dN/dE ~ E^{-1} exp(-E/kT) The last burst was also detected by INTEGRAL SPI-ACS at 539.761 s UT. We have triangulated it to an annulus centered at RA(2000) = 302.741 deg, Decl(2000) = -19.181 deg, whose radius is 28.900 +/- 0.478 deg (3 sigma). As the center line of this annulus passes 0.14 degrees from the position of SGR 1806-20, we believe that it is the source of this event. The Konus ecliptic latitude response indicates that the source of the remaining bursts is near ecliptic plane, so we suppose, that they are also originated from SGR 1806-20. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2647 SUBJECT: Bursting activity from SGR 1806-20 detected with IBAS DATE: 04/08/17 09:51:38 GMT FROM: Sandro Mereghetti at IASF/CNR S. Mereghetti, D.Gotz (IASF, Milano), N. Mowlavi, S. Shaw (ISDC), and K.Hurley (UCB/SSL) report: Two weak bursts from SGR 1806-20 have been detected with the IBIS/ISGRI instrument at UT 04:56:19.3 and 05:59:51.3 of 2004 Aug 17. Both bursts lasted 0.1 s and had a fluence of about 1.5x10-8 erg cm-2 (15-100 keV). They had significance below the threshold for automatic delivery of IBAS Alert Packets. INTEGRAL will continue to observe SGR 1806-20 until 03:10 UT of Aug 19. If stronger bursts from this source are detected, automatic Alert Packets will be distributed in real time (expected delay of 10-20 s) This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2665 SUBJECT: Increase of SGR 1806-20 activity DATE: 04/08/26 15:19:46 GMT FROM: Dmitry Frederiks at Ioffe Institute S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks on behalf of Konus-Wind and Helicon/Coronas-F teams, T. Cline on behalf of the Konus-Wind team, and A. Rau, A. von Kienlin, G. Lichti on behalf of the INTEGRAL SPI-ACS GRB team report: Recently the increase of bursting activity from SGR 1806-20 was detected by Konus-Wind, INTEGRAL SPI-ACS, and Helicon-Coronas-F. Konus-Wind has detected 7 bursts in the trigger mode and 5 bursts in the background mode. Additional SGR-like burst was detected by Helicon-Coronas-F in the background mode and triggered INTEGRAL SPI-ACS (the burst was missed by Konus-Wind due to data read out). The most recent burst detected on August 25 at 85512.611 s UT is the brightest burst ever observed by Konus-Wind from SGR 1806-20. The following table summarizes the bursts: Date Time*, Duration, Fluence, Peak Flux, Observed by** s UT s (20-200 keV) (20-200 keV) ergs/cm2 ergs/cm2 s ----------------------------------------------------------------------- 040814 45466.575 0.18 1.6E-6 2.1E-5 K(tr) 040819 22636.891 0.80 1.4E-5 2.5E-5 K(tr) 040820 71208.277 0.06 9.4E-7 3.1E-5 K(tr) 040821 35217 <3 1.7E-6 - K(bg), I 040821 61297.013 0.22 2.5E-6 2.0E-5 K(tr), I 040822 9646 <3 5.0E-7 - K(bg) 040823 22462 <3 8.0E-7 - K(bg) 040823 36755 <3 5.0E-7 - K(bg) 040823 40994.643 0.14 1.5E-6 4.5E-5 K(tr) 040823 48073.891 0.70 1.0E-5 4.2E-5 K(tr), I, H(bg) 040823 48363 <2 3.2E-6 - I, H(bg) 040823 58681 <3 6.0E-7 - K(bg) 040825 85512.611 1.10 2.1E-5 7.0E-5 K(tr), I ------------------------------------------------------------------------ * - Konus-Wind (or Helicon) time is given ** - the last column contains the s/c which observed this burst: K - Konus-Wind, I - INTEGRAL SPI-ACS, H - Helicon-Coronas-F. For Konus and Helicon in the brackets the observation mode is given: tr - trigger, bg - background. The Konus-INTEGRAL annuli for 3 bursts are: Date Time, Center Radius s UT RA DEC and its uncertainty (3sigma) deg deg deg ---------------------------------------------------- 040821 61297.013 310.141 -16.864 35.724+/-0.678 040823 48073.891 311.668 -14.712 37.647+/-0.762 040825 85512.611 314.503 -14.941 40.588+/-0.454 Because all these annuli pass through the position of SGR 1806-20, we believe that it is the source of these events. The Konus ecliptic latitude response indicates that the source of the remaining bursts (except the missed one) is near ecliptic plane, so we suppose, that they are also originated from SGR 1806-20. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2693 SUBJECT: Very bright burst detected from SGR 1806-20 DATE: 04/09/04 09:25:41 GMT FROM: Dmitry Frederiks at Ioffe Institute S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, and T. Cline on behalf of Konus-Wind team, G. Ricker, J-L Atteia, N. Kawai, D. Lamb, S. Woosley, J. Doty, R. Vanderspek, J. Villasenor, G. Crew, N. Butler, J.G. Jernigan, F. Martel, G. Prigozhin, A. Dullighan, J. Braga, R. Manchanda, G. Pizzichini, Y. Shirasaki, C. Graziani, M. Matsuoka, T. Tamagawa, T. Sakamoto, A. Yoshida, E. Fenimore, M. Galassi, T. Donaghy, C. Barraud, M. Boer, J-F Olive, and J-P Dezalay, on behalf of the HETE GRB team, and K. Hurley on behalf of the IPN team report: A very bright SGR burst was detected by Konus-Wind on August 28 at 42581.338 s UT. This burst also triggered HETE at 42569.952 s UT (H3514). We have triangulated it to an annulus centered at RA(2000) = 317.135 deg, Decl(2000) = -17.624 deg, whose radius is 42.448 +/- 1.601 deg (3 sigma). As this annulus includes the position of SGR 1806-20 and Konus ecliptic latitude response indicates that the burst source lays near ecliptic plane, we believe that SGR 1806-20 is the source of this event. As observed by Konus-Wind, the burst had a duration of 0.7 s, a fluence ~4.0x10^-5 erg/cm^2, and a peak flux ~1x10^-4 erg/cm^2 s (both in 20-200 keV range). The value of the spectral parameter kT for an OTTB spectral model (dN/dE ~ E^{-1} exp(-E/kT)) was 26 keV. This burst is the brightest one from this SGR detected so far by Konus-Wind. It is stronger, than the burst on 040825 (GCN 2665) by a factor of about 1.7 in fluence and peak flux. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2706 SUBJECT: An intense burst from SGR1806-20 DATE: 04/09/13 11:41:23 GMT FROM: Dmitry Frederiks at Ioffe Institute S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks on behalf of Konus-Wind and Helicon/Coronas-F teams, T. Cline on behalf of the Konus-Wind team, and A. Rau, A. von Kienlin, G. Lichti on behalf of the INTEGRAL SPI-ACS GRB team report: An intense SGR-like burst was detected by Konus-Wind on September 10 at 35441.919 s (09:50:41.919) UT and Helicon-Coronas-F at 35438.674 s (09:50.38.674) UT. We have triangulated it to an annulus centered at RA(2000) = 325.353 deg, Decl(2000) = -13.289 deg, whose radius is 51.241 +/- 0.156 deg (3 sigma). This burst was also observed by Integral SPI-ACS. The Konus-Wind - INTEGRAL triangulation annulus is: RA(2000) = 322.942 deg, Decl(2000) = -8.645 deg, Radius = 50.227 +/- 0.328 degrees (3 sigma). These annuli intersect to form two error boxes, one of which may be eliminated by the Konus ecliptic latitude response. The remaining error box includes the position of SGR 1806-20, so we believe that it is the source of this event. Additionaly, two SGR-like bursts were detected recently by Konus-Wind. The Konus ecliptic latitude response indicates that the source of these bursts is near ecliptic plane, so we suppose, that they are also originated from SGR 1806-20. The following table summarizes the bursts (as observed by Konus-Wind): Date Time*, Duration, Fluence, Peak Flux, s UT s (20-200 keV) (20-200 keV) ergs/cm2 ergs/cm2 s ----------------------------------------------------------------------- 040830 23313.143 0.14 2.4E-6 3.6E-5 040908 45466.575 0.33 8.3E-6 5.0E-5 040910 35441.919 0.58 1.7E-5 4.6E-5 ------------------------------------------------------------------------ //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2760 SUBJECT: SGR 1806-20 still active DATE: 04/10/04 09:46:14 GMT FROM: Diego Gotz at IASF-CNR D. Gotz, S. Mereghetti (IASF-Milano) and F. Mirabel (SAP, Saclay) report: The soft repeater SGR 1806-20 continues to be in an active bursting state. Six bursts have been detected by IBAS during INTEGRAL Galactic Center Core Program observations, performed between September 30 and October 2, 2004. Burst times, approximate durations, and fluences (15-100 keV) are reported below: Time UT Duration (s) Fluence (erg cm-2) 2004-09-30T13:03:42.07 0.3 4.0E-8 2004-10-01T06:03:29.81 0.2 5.0E-8 2004-10-01T18:45:53.28 0.1 4.5E-8 2004-10-01T22:03:13.29 0.1 1.2E-7 2004-10-02T02:47:29.10 0.15 1.5E-7 2004-10-02T10:10:26.96 0.2 4.5E-7 Being the source very active, IBAS Alert messages regarding SGR 1806-20 are still disabled. This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2763 SUBJECT: Very strong outburst from SGR 1806-20 detected with INTEGRAL DATE: 04/10/05 14:49:51 GMT FROM: Sandro Mereghetti at IASF/CNR S. Mereghetti, D. Gotz (IASF-Milano), J.Borkowski (CAMK-Torun), M.Beck (ISDC-Versoix) on behalf of the IBAS Localization Team and F.I.Mirabel (SAp-Saclay) on behalf of the INTEGRAL Science Working Team report: A strong increase in the activity of SGR 1806-20 has been detcted by IBAS starting at 13:57 UT of October 5. The activity consists of an approximately 6 min long, multipeaked outburst, followed by a few shorter bursts. During the peaks of the long outburst the counting rate in the IBIS/ISGRI detector saturates the available telemetry. Analysis is in progress to estimate the event fluence and spectrum. Rapid observations at other wavelengths are encouraged. This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2764 SUBJECT: Bursts from SGR 1806-20: Preliminary INTEGRAL results DATE: 04/10/05 16:17:17 GMT FROM: Sandro Mereghetti at IASF/CNR D. Gotz, S. Mereghetti (IASF-Milano), F.I Mirabel (SAp-Saclay) report: The activity from SGR 1806-20 reported in GCN Circ. 2763 consists of at least two main bursts whose peak flux and detailed temporal structure are uncertain due to satellite telemetry saturation. Both are detected up to at least 200 keV in the IBIS/ISGRI instrument. The first burst starts at 13:56:43 UT and lasts about 20 s. Its spectrum over the 15-200 keV range is well fit by an Optically Thin Thermal Bremsstrahlung model with temperature kT = 45+/-3 keV. A preliminary analysis gives a lower limit on its fluence of about 1.e-5 erg/cm2 (15-100 keV). The second burst starts at 13:59:33 UT and lasts about 40 s. Its OTTB temperature is kT = 57+/-3 keV and the preliminary lower limit on its fluence is 2.e-5 erg/cm2 (15-100 keV). This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2823 SUBJECT: Bright bursts from SGR1806-20 DATE: 04/10/19 13:27:31 GMT FROM: Dmitry Frederiks at Ioffe Institute S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks on behalf of Konus-Wind and Helicon/Coronas-F teams, T. Cline on behalf of the Konus-Wind team, and A. Rau, A. von Kienlin, G. Lichti on behalf of the INTEGRAL SPI-ACS GRB team report: Two bright SGR-like events were detected by Konus-Wind on October 16 at 66284.062s UT and October 17 at 23771.551s UT. Both events were also detected by INTEGRAL SPI-ACS, Wind-INTEGRAL triangulation gives the following annuli: The first event: Alpha = 191.74323 Delta =-17.37563 Radius = 75.32431 +/-0.37658 The annulus passes 0.021 deg (0.17 sigma) from SGR 1806-20. The second event: Alpha = 191.85595 Delta =-16.48234 Radius = 75.45488 +/- 0.27746 The annulus passes 0.053 deg (0.57 sigma) from SGR 1806-20. According to the Konus-Wind data the first event on 041016 had a duration of 0.12 sec, fluence 6.4x10-6 erg cm-2, and peak flux 8.5x10-5 erg cm-2 s-1, both in 20-200 keV range. OTTB fit gives parameter kT = 26.5 +/- 1.5 keV The 041017 event had a duration of main pulse of 1.6 sec, fluence 6.5x10-5 erg cm-2, and peak flux 6.7x10-5 erg cm-2 s-1, both in 20-200 keV range. A considerable spectral evolution was observed, OTTB fit gives the following values of kT during event: ------------------------------------ Time after trigger kT sec keV ------------------------------------ 0 - 0.256s 24.1 +/- 0.5 0.256 - 0.768s 20.4 +/- 0.5 0.768 - 1.6s 17.5 +/- 0.7 ------------------------------------ Following the main pulse there were two weaker events (times are given after the trigger), at +11.287 s (fluence ~2x10-7 erg cm-2) and at +157.2s (fluence ~4.5x10-7 erg cm-2). //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2831 SUBJECT: Summary of the recent bursts from SGR 1806-20 DATE: 04/11/04 14:12:33 GMT FROM: Dmitry Frederiks at Ioffe Institute S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks on behalf of Konus-Wind and Helicon/Coronas-F teams, T. Cline on behalf of the Konus-Wind team, and A. Rau, A. von Kienlin, G. Lichti on behalf of the INTEGRAL SPI-ACS GRB team report: SGR 1806-20 remains in the active state. Since the last SGR burst 041017, listed in GCN 2823, Konus-Wind and Helicon-Coronas-F have detected seven SGR-like bursts in the trigger mode. Two of them were also detected by INTEGRAL SPI-ACS. The most recent intense SGR burst was detected by Helicon-Coronas-F today (041104) at 04:17:08.929 UT. Konus-Wind data aren't available yet. The following table summarizes the bursts: Date Time, Instr* Duration, Fluence, Peak Flux, kT** s UT s (20-200 keV) (20-200 keV) keV ergs/cm2 ergs/cm2 s ----------------------------------------------------------------------- 041026 76305.409 K 0.54 3.0E-6 2.4E-5 21.4+/-1.2 041027 35196.737 K 0.55 5.0E-6 2.6E-5 18.6+/-1.1 041029 22099.384 K 0.16 2.5e-6 3.4E-5 17.7+/-1.3 041031(a) 57535.834 H 0.056 4.7e-7 1.2e-5 17.8+/-1.6 041031 61900.552 K, I 0.70 1.2e-5 4.4e-5 18.9+/-0.6 041102(b) 26875.713 K 0.19 1.1e-5 9.9e-5 22.6+/-1.2 041104(c) 15428.929 H, I 1.6 1.9e-5 2.0e-5 21.8+/-0.5 ------------------------------------------------------------------------ * - the intrument, which detected the burst: K = Konus-Wind H = Helicon-Coronas-F I = INTEGRAL SPI-ACS ** - the last column contains the values of spectral parameter kT for the OTTB spectral model: dN/dE ~ E^{-1} exp(-E/kT) (a) - this burst was also observed by Konus-Wind in the background mode. Estimated time delay is consistent with SGR 1806-20 position. (b) - this burst was also observed by Helicon-Coronas-F in the background mode. Estimated time delay is consistent with SGR 1806-20 position. (c) - We have triangulated it to Coronas-INTEGRAL annulus centered at RA(2000) = 225.846 deg, Decl(2000) = 44.432 deg, whose radius is 77.4 ± 4.0 deg (3 sigma). The center line of this annulus passes 0.02 degrees from the position of SGR 1806-20. The Konus-Wind ecliptic latitude response indicates that the source of the remaining bursts is near ecliptic plane, so we suppose, that they are also originated from SGR 1806-20. The peak flux of the burst on 041102 was nearly the same as the peak flux of the brighest burst detected by Konus-Wind from SGR 1806-20 on 040828 (GCN 2693). //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2896 SUBJECT: Very high activity of SGR 1806-20 DATE: 04/12/22 16:57:06 GMT FROM: Dmitry Frederiks at Ioffe Institute S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks and T. Cline on behalf of the Konus-Wind team, report: During 21 December more than 30 SGR-like bursts were detected by Konus-Wind and Helicon-Coronas-F with peak fluxes varied from 5e-7 to 8e-5 erg /cm2 s. The time interval between bursts varied from seconds to hours. The triangulation of several these bursts indicated that their origin is SGR 1806-20. This is the second series of bursts from this source. The previous one was detected on 5 October (GCN 2769). Now we have the data till 01:28 UT December 22. The last burst is seen at 00:50:52 s UT in the Helicon background data. Details on triangulation and the full list of bursts with their characteristics will be given later. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2920 SUBJECT: Giant flare from SGR 1806-20 detected by INTEGRAL DATE: 04/12/29 11:19:07 GMT FROM: Sandro Mereghetti at IASF/CNR J.Borkowski (CAMK, Torun), D. Gotz, S. Mereghetti (IASF, Milano), N.Mowlavi, S.Shaw, M.Turler (ISDC, Versoix), report: A large flare most likely coming from the soft repeater SGR 1806-20 has been detected with INTEGRAL on December 27 at 21:30:26 UT. The flare caused a large and rapid increase in the count rate of the SPI ACS which reached a peak flux of 2x10^6 counts/s (compared to a background level of 88,000 counts/s ). The initial spike, lasting about 1.5 s, is followed by a 300 s long tail in which pulsations at 7.57 s are clearly visible. The IBAS ACS system triggered on a fainter event occurring about 140 s before the main flare and possibly due to a precursor from the same source. No positional information is available with the SPI ACS data. The shape of the light curve, similar to that of the 27 August 1998 flare from SGR 1900+14, but with a periodicity of 7.6 s, indicates that SGR 1806-20 is the most likely origin of the observed event. This would be the first giant flare observed from SGR 1806-20. At the time of the flare, INTEGRAL was pointing at 106 degrees from the direction of SGR 1806-20, which was outside the fields of view of the imaging instruments. See also the News section of http://ibas.mi.iasf.cnr.it/ for further details of the ongoing analysis This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2921 SUBJECT: IPN localization of giant flare from SGR1806-20 DATE: 04/12/29 12:30:42 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley and T. Cline, on behalf of the Ulysses and Mars Odyssey GRB teams, I. Mitrofanov, S. Charyshnikov, V. Grinkov, A. Kozyrev, M. Litvak, and A. Sanin, on behalf of the HEND-Odyssey GRB team, and W. Boynton, C. Fellows, K. Harshman, C. Shinohara and R. Starr, on behalf of the GRS-Odyssey GRB team, report: The giant flare observed by INTEGRAL (SPI-ACS - GCN 2920) was also detected by Mars Odyssey (GRS). Data from other IPN spacecraft have not been received yet. A very preliminary analysis indicates that the arrival time at Odyssey is indeed consistent with an arrival direction from SGR1806-20. Further analysis is underway and will be reported later. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2922 SUBJECT: The giant outburst from SGR 1806-20 DATE: 04/12/29 13:18:07 GMT FROM: Dmitry Frederiks at Ioffe Institute E. Mazets, S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin, and T. Cline on behalf of the Konus-Wind team, report: On December 27, 2004, the Konus-Wind instrument detected a giant flare from SGR 1806-20. The flare was preceded by a high emission of recurrent soft bursts. A series of numerous bursts occurred on October 5. On the analogy of the behaviour of SGR 1900+14 before the giant flare on 1998 August 27, it was possible to expect, that SGR 1806-20 is close to generation of a giant flare (GCN 2769). Another series began on December 21 and lasted until the giant flare. These bursts were strong in their flux, exhibiting a well pronounced spectral variability and in some cases unusual spectral features. A record of the giant outburst was triggered by a recurrent burst, which was the strongest in the series. The giant outburst occurred on 142 s after this trigger. The flare started with a very intense initial pulse, resulting in overloading of the detector. It was followed by a long pulsating tail lasted more than 380 s. A measured period of the pulsations is 7.57 ± 0.07 s, indicating its increasing since 2000, when value of 7.49 s was determined in Chandra observations of X-ray persistent flux (Kaplan et al., 2002, ApJ, 564, 935) . Giant outbursts were observed earlier in SGR 0526-66 on 1979 March 5, in SGR 1627-41 on 1998 June 18, in SGR 1900+14 on 1998 August 27. The event of December 27 completes this list for all of well known SGRs. After the outburst, SGR 1806-20 continues to emit recurrent bursts. A determination of energetic and spectral parameters of the outburst will take some time because of a huge intensity of the initial pulse. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2923 SUBJECT: Detection of the SGR 1806-20 giant outburst back-scattered by the DATE: 04/12/29 19:32:36 GMT FROM: Dmitry Frederiks at Ioffe Institute S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks on behalf of Konus-Wind and Helicon/Coronas-F teams, and T. Cline on behalf of the Konus-Wind team report: We present an evidence of Helicon-Coronas-F detection of the giant outburst from SGR1806-20 which was scattered back from the Moon. At the time of the outburst SGR1806-20 was occulted by the Earth for Coronas-F. A short burst triggered Helicon at 21:30:29.303s UT on Dec 27. A time delay between Konus-Wind and Helicon-Coronas-F detections is -7.70 s. This value corresponds exactly to burst travelling time from the Wind to the Moon and back to the Coronas-F. The spectrum of the event detected by the Helicon is highly unusual. It looks like a broad assymetric line peaked at ~100 keV. Apparently such a shape corresponds to back-scattering peak of a huge initial pulse of the outburst. The fluence of event is about 7.5x10^-7 erg cm-2 in 25-400 keV range. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2928 SUBJECT: VLA observations of SGR 1806-20 DATE: 05/01/03 20:27:48 GMT FROM: Patrick B. Cameron at Caltech P. B. Cameron (Caltech) and S. R. Kulkarni (Caltech) report: "We observed the position of SGR 1806-20 with the Very Large Array (VLA) in A-configuration on 2005 Jan 3.81 UT (t ~ 6.9 days after the giant flare, GCN #2920). We detect a radio source coincident with the X-ray position reported by Kaplan et al. (2002, ApJ, 564, 935) at the approximate freqeucnies and flux densities listed below. Freq (GHz) Flux density (mJy) -------------------------------- 4.86 73 8.46 41 This is a factor of brighter of 100 times brighter at 8.46 GHz than SGR 1900+14 at peak. Further observations are planned. The National Radio Astronomy Observatory is operated by Associated Universities, Inc., under cooperative agreement with the National Science Foundation." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2930 SUBJECT: VLA observations of SGR 1806-20 DATE: 05/01/03 21:00:02 GMT FROM: Patrick B. Cameron at Caltech P. B. Cameron (Caltech) and S. R. Kulkarni (Caltech) report: "We observed the position of SGR 1806-20 with the Very Large Array (VLA) in A-configuration on 2005 Jan 3.81 UT (t ~ 6.9 days after the giant flare, GCN #2920). We detect a radio source coincident with the X-ray position reported by Kaplan et al. (2002, ApJ, 564, 935) at the approximate freqeucnies and flux densities listed below. Freq (GHz) Flux density (mJy) -------------------------------- 1.43 164 Further observations are planned. The National Radio Astronomy Observatory is operated by Associated Universities, Inc., under cooperative agreement with the National Science Foundation." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2931 SUBJECT: DETECTION OF POLARIZATION OF THE RADIO EMISSION FROM SGR 1806-20 DATE: 05/01/03 21:16:21 GMT FROM: Peter Woods at UAH/MSFC DETECTION OF POLARIZATION OF THE RADIO EMISSION FROM SGR 1806-20 B. M. Gaensler (CfA), C. Kouveliotou (NASA/MSFC, NSSTC), R. Wijers (University of Amsterdam), M. Garrett (JIVE), M. Finger, P. Woods, S. Patel (USRA, NSSTC), M. McLaughlin (Jodrell Bank) report on behalf of a larger team: Further to the reports on the radio emission from SGR 1806-20 (Cameron & Kulkarni, GCN 2928, and Gaensler et al, GCN 2929, Atel # 373) we detect linear polarization from the source at 1.4, 4.9, 8.5 GHz at a level of at least 2.6, 0.9, 3.8%, respectively. We caution, however, that these are very preliminary results and more detailed analysis is underway to account for the possibility of polarization leakage from the total intensity signal. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2933 SUBJECT: Second-epoch VLA observations of SGR 1806-20 DATE: 05/01/04 15:15:00 GMT FROM: Chryssa Kouveliotou at MSFC B. M. Gaensler (CfA), C. Kouveliotou (NASA/MSFC, NSSTC), R. Wijers (U. Amsterdam), M. Garrett (JIVE), M. Finger, P. Woods, S. Patel (USRA, NSSTC), M. McLaughlin (Jodrell Bank), R. Fender (U. Southampton), T. Delaney (CfA) report on behalf of a larger team: We observed the soft gamma-ray repeater SGR 1806-20 with the Very Large Array (VLA) in the A-configuration for a second time on January 4, 2005 for one hour (14:15-15:15 UT). We detect the source at the same coordinates as reported by Gaensler et al. (GCN 2929). Preliminary flux levels, including improved estimates of the fluxes reported in GCN 2929, are as follows (the numbers in parentheses indicate 3 sigma errors in the last decimal points): Frequency Flux (2005 Jan 03.8) Flux (2005 Jan 04.6) (GHz) (mJy) (mJy) --------- -------------------- -------------------- 1.4 172(4) 135(10) 4.9 80(1) 66(2) 8.5 53(1) 38(5) These results indicate a decay in the flux at a rate of approximately 1.9 mJy/hour at 1.4 GHz. At the same time the spectrum has remained constant. On Jan 3, 2005 the spectral index (in the sense F_nu ~ nu^alpha) was alpha = -0.65+/-0.05, while on Jan 4, 2005 the spectral index was -0.61+/-0.06. A reanalysis of the VLA data from 3 Jan 2004 (GCN 2928, 2929) suggests that the radio source associated with SGR 1806-20 is slightly extended at both 4.9 and 8.5 GHz. Assuming that the underlying geometry is an optically thin, spherical thin shell, both data-sets independently suggest a source of approximate diameter 50-100 milliarcseconds. This implies a projected expansion speed of approx (0.3-0.6)c over the 7 days since the initial Giant SGR flare (assuming a source distance of 15.1 kpc; Eikenberry, S. et al., ApJ 616, 506, 2004). Further radio observations of this source with the Westerbork Synthesis Radio Telescope (WSRT), the MERLIN VLBI network and the Parkes Radio Observatory are currently underway or are being scheduled and will be reported as they are analyzed. We will continue monitoring the source with the VLA until it fades below detection level. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2934 SUBJECT: Second Epoch VLA observations of SGR 1806-20 DATE: 05/01/04 17:32:20 GMT FROM: Patrick B. Cameron at Caltech P. B. Cameron (Caltech) and S. R. Kulkarni (Caltech) report: "We observed a second epoch of the position of SGR 1806-20 with the Very Large Array (VLA) in A-configuration on 2005 Jan 4.59 UT (t ~ 7.7 days after the giant flare, GCN #2920). We again detect a radio source coincident with the X-ray position reported by Kaplan et al. (2002, ApJ, 564, 935) at the approximate freqeuncies and flux densities listed below. Freq (GHz) Flux density (mJy) -------------------------------- 1.43 128 +/- 5 4.86 62 +/- 2 8.46 37 +/- 5 Error Bars are 1 sigma. The combination of these measurements with those reported 2005 Jan 03 (GCN #2928, #2929, 2930, ATEL 373) suggest a decay exponent (F ~ t^beta) of beta = -2.2 at 1.4 GHz. The spectral index (F ~ nu^alpha) has remained constant over the two epochs with alpha = -0.74 and -0.68. The National Radio Astronomy Observatory is operated by Associated Universities, Inc., under cooperative agreement with the National Science Foundation." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2935 SUBJECT: Third epoch observations of SGR 1806-20 with VLA DATE: 05/01/05 16:16:11 GMT FROM: Chryssa Kouveliotou at MSFC B. M. Gaensler (CfA), C. Kouveliotou (NASA/MSFC, NSSTC), J. Gelfand (CfA), R. Wijers (U. Amsterdam), M. Garrett (JIVE), M. Finger, P. Woods, S. Patel (USRA, NSSTC), M. McLaughlin (Jodrell Bank), R. Fender (U. Southampton), T. Delaney (CfA) report on behalf of a larger team: We observed the soft gamma-ray repeater SGR 1806-20 with the Very Large Array (VLA) in the A-configuration for a third time on January 5, 2005 for one hour (mean epoch approx 1600 UT). (See GCN #2928, #2929, #2933; ATEL #373, #375 for earlier results). Preliminary flux levels for 2005-Jan-05.66 are as follows: 4.9 GHz: 57(2) mJy 8.5 GHz: 31(2) mJy The source continues to fade, but at a slower rate consistent with a power law of index -1.6(2) at 4.9 GHz. Further observations will take place on January 6. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2937 SUBJECT: ATCA observations of SGR 1806-20 DATE: 05/01/05 21:01:30 GMT FROM: Chryssa Kouveliotou at MSFC J. Gelfand (CfA), B. M. Gaensler (CfA), K. Newton-McGee (U. Sydney), C. Kouveliotou (NASA/MSFC, NSSTC), R. Wijers (U. Amsterdam), M. Garrett (JIVE), M. Finger, P. Woods, S. Patel (USRA, NSSTC), M. McLaughlin (Jodrell Bank), R. Fender (U. Southampton), T. Delaney (CfA) report on behalf of a larger team: We observed the soft gamma-ray repeater SGR 1806-20 with the Australian Telescope Compact Array (ATCA) on January 5, 2005 for two hours (mean epoch approx 2000 UT). (See GCN #2928, #2929, #2933; ATEL #373, #375 for earlier results). Preliminary flux levels for 2005-Jan-05.83 are as follows: 2.4 GHz: 87(2) mJy 4.8 GHz: 53(1) mJy 8.6 GHz: 29(1) mJy We observe a possible break in the source spectrum. The power law spectral index between 4.8 and 8.6 GHz is -1.0, while between 2.4 and 4.8 GHz the index is -0.7. Further observations will take place on January 6. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2938 SUBJECT: SGR 1806-20: Temporal and Spectral behavior of radio transient DATE: 05/01/06 14:01:30 GMT FROM: Dale A. Frail at NRAO P. B. Cameron (Caltech) and S. R. Kulkarni (Caltech) report: "We have carried out a more thorough calibration of the three VLA epochs of the fading radio source toward SGR 1806-20 (GCN#s 2928, 2929, 2930, 2933, 2934, 2935). Combining this with the data from a fourth epoch observation made with the Australia Compact Array (GCN# 2937) we do a joint fit of the form: F_nu \propto t^\alpha nu^\beta. The best fit values are alpha= -1.62+/-0.06 and beta=-0.75+/-0.03. There is evidence of deviations from this simple power-law behavior. Fitting the decay rate alpha at each frequency we find a systematic steepening. The value of alpha is -1.0 at 1.4 GHz, -1.5 at 4.9 GHz, and -2.2 at 8.5 GHz. This behavior is reminiscent of the broadband afterglow of GRB 991216 (Frail et al. ApJ, 538, 129). A plot of the light curves is at: http://www.aoc.nrao.edu/~dfrail/sgr1806lc.eps. The National Radio Astronomy Observatory is operated by Associated Universities, Inc., under cooperative agreement with the National Science Foundation. The Australia Telescope is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2939 SUBJECT: SGR 1806-20: Low frequency GMRT results; submission to GCN circulars DATE: 05/01/06 15:16:20 GMT FROM: Poonam Chandra at Tata Inst. Fund.Res. SGR 1806-20: Low frequency GMRT results P. Chandra (Tata Institute of Fundamental Research (TIFR), Mumbai), reports the detection of radio emission from the soft gamma-ray repeater SGR 1806-20 with the Giant Metrewave Radio Telescope (GMRT) in the 610/235 MHz bands for 1.16 hours on 2005 Jan. 04 (mean epoch approximately 0949 UT). The preliminary flux densites for 2005-Jan-04.409 were: 608 MHz: 198.9 (11.9) mJy 240 MHz: 242.6 (14.9) mJy The last digits in the brackets indicate 1 sigma error bars. She notes that the power law index beween the two frequencies is: -0.21 (0.09). This index is substantially flatter than the corresponding power law index reported in the higher frequency VLA observation on 2005 Jan 4.59 UT by Cameron and Kulkarni (GCN 2934) (alpha = -0.74 at 1.4 GHz) or -0.61 (0.06) reported by Gaensler et al at the same time (GCN 2933). Further observations with the GMRT at other low frequencies are also planned. [GCN OPS NOTE (06Jan05): This Circular was delayed by 3 hours until the submitor could be added to the list.] //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2940 SUBJECT: Fourth Epoch VLA observations of SGR 1806-20 DATE: 05/01/06 21:28:18 GMT FROM: Patrick B. Cameron at Caltech P. B. Cameron (Caltech) and S. R. Kulkarni (Caltech) report: "We observed a fourth epoch of the position of SGR 1806-20 with the Very Large Array (VLA) in A-configuration on 2005 Jan 6.77 UT (t ~ 9.9 days after the giant flare. See GCN #2920, #2928, #2929, #2933, #2934, #2935, ATEL #373, #375). We find the following preliminary flux densities: Freq (GHz) Flux density (mJy) -------------------------------- 1.43 96 +/- 2 4.86 39 +/- 2 8.46 24 +/- 1 Error Bars are 1 sigma. We find an angular size at 8.46 GHz of about 80 mas. We see no variation in this diameter over the last 4 days. The National Radio Astronomy Observatory is operated by Associated Universities, Inc., under cooperative agreement with the National Science Foundation." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2941 SUBJECT: Further ATCA observations of SGR 1806-20 DATE: 05/01/07 15:19:09 GMT FROM: Bryan Gaensler at Harvard-Smithsonian/CfA J. Gelfand (CfA), B. M. Gaensler (CfA), K. Newton-McGee (U. Sydney), C. Kouveliotou (NASA/MSFC, NSSTC), G, Taylor (NRAO), R. Wijers (U. Amsterdam), M. Garrett (JIVE), M. Finger, P. Woods, S. Patel (USRA, NSSTC), M. McLaughlin (Jodrell Bank), R. Fender (U. Southampton) report on behalf of a larger team: We observed the soft gamma-ray repeater SGR 1806-20 with the Australia Telescope Compact Array (ATCA) using five 6-km baselines on January 6, 2005 (0530-0730 UT and 1930-2130 UT) and on January 7, 2005 (0430-0500 UT). Preliminary flux levels, are as follows (the number in parentheses indicates the 1-sigma uncertainty in the last significant figure): Frequency Flux (Jan 06.26) Flux (Jan 06.77) Flux (Jan 07.20) (GHz) (mJy) (mJy) (mJy) --------- ------------ -------------- ----------------- 1.4 103(2) 90(2) 86(3) 2.4 68(2) 66(2) 54(1) 4.8 45(2) 38(1) 6.1 30(2) 8.6 23(1) There is clear evidence for a spectral break from the first two of the above epochs, possibly decreasing to lower frequencies as a function of time. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2942 SUBJECT: SGR 1806-20 and extragalactic short-duration GRBs DATE: 05/01/07 16:31:10 GMT FROM: Arnon Dar at Technion-Israel Inst. of Tech If the giant short peak of the giant flare from SGR 1900+14 on 27/12/2004 (GCN 2920, GCN 2923, GCN 2936, GCN2927) at an estimated distance of 15 kpc (Corbel and Eikenberg A\&A 419, 191, 2004) could have been seen by BATSE as a hard, short-duration GRB up to a distance of 80 Mpc (GCN 2936), then SGRs in external galaxies can be the main source of the hard, short-duration GRBs seen by BATSE: The local optical luminosity within a distance of 80 Mpc is about 10^4 times the Milky Way [MW] luminosity, (\rho_L=1.84 10^8 h L[sun] Mpc^{-3}; L[MW]=2.4 10^{10} L[sun], where, h=0.65, is the Hubble constant in units of 100 km/s/Mpc). If the observed rate from Earth of such bursts per Milky Way luminosity is \sim 1 in 15 years (one since the launch of CGRO), it yields, before correcting for triggering efficiency and for sky solid angle coverage, an observable rate by BATSE of about 2 hard, short-duration, cosmic GRBs per day, independent of the beaming angle. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2943 SUBJECT: Further VLA observations of SGR 1806-20 DATE: 05/01/07 22:09:14 GMT FROM: Bryan Gaensler at Harvard-Smithsonian/CfA B. M. Gaensler (CfA), G. Taylor (NRAO), J. Gelfand (CfA), C. Kouveliotou NASA/MSFC, NSSTC), R. Wijers (U. Amsterdam), M. Garrett (JIVE), G. Taylor (NRAO), M. McLaughlin (Jodrell Bank), R. Fender (U. Southampton), K. Newton-McGee (U. Sydney) report on behalf of a larger team: We observed the soft gamma-ray repeater SGR 1806-20 with the Very Large Array (VLA) in its A configuration on 2005, January 7, UT 2100-2200. Preliminary flux levels at epoch Jan 07.90 are as follows (the numbers in parentheses indicate 1 sigma errors in the last significant figure): Frequency Flux (Jan 07.90) (GHz) (mJy) --------- ------------ 1.4 75(5) 4.8 28(1) 8.6 17(1) The spectrum is consistent with a single power law over this range of spectral index -0.81+/-0.05, significantly steeper than when the radio source was first detected on 2005 Jan 3 (GCN #2928, #2929, $2930). //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2945 SUBJECT: SGR1806-20: Swift-BAT observations of two additional bursts DATE: 05/01/09 18:11:58 GMT FROM: David Palmer at LANL D. Palmer (LANL), S. Barthelmy, L. Barbier, J. Cummings (GSFC), E. Fenimore (LANL), R. Fink (GSFC), N. Gehrels (GSFC), D. Hullinger (GSFC/UMD), S. Hunsberger (PSU), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), P. Matteo (ASDC) K. McLean (LANL), J. Nousek (PSU), P. Meszaros (PSU), A. Parsons (GSFC), T. Sakamoto (GSFC), G. Sato (ISAS), M. Suzuki (Saitama), J. Tueller (GSFC) on behalf of the Swift-BAT team: During a follow-up observation on the SGR1806-20, the Burst Alert Telescope (BAT) on Swift has detected two more outbursts, indicating that this source is still in an active phase 11 days after the 041227 giant flare. Each burst was ~0.1 second long and was within BAT's partially-coded (35%) field of view (fully-coded viewing was prevented by the Sun observing constraint). At 2005-01-07 02:08:21 a small outburst (0.4 counts/cm^2, 15-100 keV) was localized on-board at RA=272.154, DEC=-20.374 (J2000) (6 arcmin from the VLA position, Gaensler et al., 2005 GCN#2920). At 2005-01-07 13:12:27 a larger but softer outburst (1.6 counts/cm^2, 15-100 keV) was localized on-board at RA=272.156, DEC=-20.409 (J2000) (0.5 arcmin from the VLA position). //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2946 SUBJECT: SGR 1806-20: Further VLA Observations DATE: 05/01/10 15:10:43 GMT FROM: Patrick B. Cameron at Caltech P. B. Cameron (Caltech) and S. R. Kulkarni (Caltech) report: "We observed the soft gamma-ray repeater SGR 1806-20 with the Very Large Array (VLA) in A-configuration on 2005 Jan 10.60 UT. We find the following preliminary flux densities: Freq (GHz) Flux density (mJy) -------------------------------- 8.46 8 +/- 1 The National Radio Astronomy Observatory is operated by Associated Universities, Inc., under cooperative agreement with the National Science Foundation." -------------------------------------- P. Brian Cameron Caltech Astrophysics Phone: (626) 395-6857 //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2947 SUBJECT: SGR 1806-20: Further low frequency GMRT results DATE: 05/01/13 15:01:53 GMT FROM: Poonam Chandra at Tata Inst. Fund.Res. SGR 1806-20: Further low frequency GMRT results P. Chandra on behalf of GMRT observatory reports the detection of radio emission from the SGR 1806-20 with the Giant Metrewave Radio Telescope (GMRT) in the 610 MHz band (with resolution 6-10") on the following dates: 608 MHz: 6 Jan 2005 111.8 (6.6) mJy 7 Jan 2005 98.8 (29.3) mJy 8 Jan 2005 83.8 (9.2) mJy 9 Jan 2005 74.3 (14.5) mJy The values quoted here are after subtracting the extended emission contribution from the SGR and doing the Tsys corection by a factor of 1.8. The modified value of 608 MHz flux density on 4 Jan 2005 observation is 231.7 (16.7) mJy (uncorrected value 199 mJy in reported in GCN 2939). This new value is after subtracting the extended emission from the SGR and modified with Tsys correction factor of 1.8. We shall report separately the 235 MHz band fluxes of SGR 1806-20 on these days (including 4 Jan 2005 observations (reported in GCN 2939)) treated similarly. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2948 SUBJECT: SGR 1806-20: Further VLA Observations DATE: 05/01/13 20:20:42 GMT FROM: Patrick B. Cameron at Caltech On Mon, 10 Jan 2005, P Brian Cameron wrote: P. B. Cameron (Caltech) and S. R. Kulkarni (Caltech) report: "We observed the soft gamma-ray repeater SGR 1806-20 with the Very Large Array (VLA) in A-configuration on 2005 Jan 13.8 UT. We find the following preliminary flux densities: Freq (GHz) Flux density (mJy) -------------------------------- 8.46 5.3 +/- 0.4 The National Radio Astronomy Observatory is operated by Associated Universities, Inc., under cooperative agreement with the National Science Foundation." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2950 SUBJECT: SGR 1806-20: RXTE/PCA pulse frequency during flare DATE: 05/01/14 18:00:12 GMT FROM: Peter Woods at UAH/MSFC Pulse Frequency of SGR 1806-20 during the Giant Flare P.M. Woods, M. Finger, S. Patel (USRA, NSSTC), C. Kouveliotou (NASA/MSFC, NSSTC), Y. Rephaeli (UCSD), D. Gruber (Eureka), M. Persic (Obs.Ast.Trieste), R. Rothschild (UCSD), D. Palmer, N. Gehrels, S. Barthelmy, E. Smith, J. Swank, and C. Markwardt (GSFC) report: We have re-analyzed the RXTE PCA data of the giant flare of 2004 December 27 from SGR 1806-20. We find that the pulse period reported in GCN #2927 of 7.579 +/- 0.002 s was strongly biased by pulse profile changes during the tail of this flare. Excluding the first ~60 s of the flare where pulse profile changes are strongest, we measure a barycenter-corrected pulse period of 7.5605 +/- 0.0006 s, significantly different than the previously reported measurement. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3002 SUBJECT: SGR1806-20: Swift-BAT detection of a large normal burst DATE: 05/01/30 23:52:20 GMT FROM: Scott Barthelmy at NASA/GSFC G. Sato (ISAS), L. Antonelli (INAF-OAR), S. Barthelmy, L. Barbier (GSFC), M. Cropper (MSSL), J. Cummings (GSFC), E. Fenimore (LANL), R. Fink (GSFC), M. Galassi (LANL), N. Gehrels (GSFC), D. Hullinger (GSFC/UMD), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), P. Meszaros (PSU), K. McLean (LANL), D. Palmer (LANL), A. Parsons, T. Sakamoto (GSFC), M. Suzuki (Saitama), J. Tueller (GSFC) on behalf of the Swift-BAT team: Swift-BAT triggered on an outburst from SGR1806-20 at 22:38:26.86 UT 30 Jan 05. This is a large normal burst from this source. The peak rate is 340,000 cnts/sec (1-sec average). There was a single spike with a 0.4-sec rise, a 4.2-sec decay, with additional emission extending out to ~T+15 sec. On top of this tail, there are five spikes at T+7, T+17, T+32, T+85, and T+118sec. The fluence is ~1x10e-5 erg/cm2 (15-350 keV). We note that this is five orders of magnitude smaller than the giant flare from this source on 27 Dec 04. Also note that there was a burst from this source earlier today at 20:45:26 UT with a peak rate of ~4000 cnts/sec (0.128-sec average) and a duration of ~0.5 sec. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3070 SUBJECT: Ongoing activity of SGR 1806-20 after the giant flare DATE: 05/03/05 15:47:16 GMT FROM: Dmitry Frederiks at Ioffe Institute S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks on behalf of Konus-Wind and Helicon/Coronas-F teams, and T. Cline on behalf of the Konus-Wind team report: SGR-like burst 050304 was detected by Konus-Wind at 10:17:14.537 UT and Helicon-Coronas-F at 10:17:17.941 UT. We have triangulated it to an annulus centered at RA(2000) = 321.683 deg, Decl(2000) = -15.478 deg, whose radius is 47.167 ± 0.092 deg (3 sigma). As the center line of this annulus passes 0.033 degrees (1.1 sigma) from the position of SGR 1806-20 and the Konus ecliptic latitude response indicates that the source of the burst is near ecliptic plane, we conclude that this burst originated from SGR 1806-20. The burst had a duration of 0.13 sec, fluence 7.9x10-7 erg cm-2, and peak flux 8.7x10-6 erg cm-2 s-1, both in 20-200 keV range. The time-integrated spectrum of the burst can be fitted by the OTTB spectral model: dN/dE ~ E^{-1} exp(-E/kT), with kT = 22 ± 1 keV. Since the giant flare on 2004 December 27, Konus-Wind and/or Helicon-Coronas-F has detected 10 SGR-like bursts in the trigger mode, probably originated from SGR 1806-20. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3138 SUBJECT: Swift-BAT detection of a bright outburst from SGR1806-20 DATE: 05/03/23 03:31:54 GMT FROM: Scott Barthelmy at NASA/GSFC S. Barthelmy, L. Barbier (GSFC), J. Cummings (GSFC/NRA), E. Fenimore (LANL), N. Gehrels (GSFC), D. Hullinger (UMD), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/NRC), G. Sato (ISAS), M. Suzuki (Saitama), J. Tueller (GSFC) on behalf of the Swift-BAT team: At 02:38:21.10 2005-03-23 UT Swift-BAT triggered on a bright outburst from SGR1806-20. There were two short peaks each ~0.4 sec in duration, each with a peak count rate of ~160,000 counts/sec. There was a smaller pre-trigger peak of ~30,000 counts/sec at T-0.7 sec. More than 99% of the emission is below 100 keV. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3343 SUBJECT: Renewal of SGR 1806-20 activity DATE: 05/05/03 15:18:35 GMT FROM: Valentin Pal'shin at Ioffe Inst S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks on behalf of Konus-Wind and Helicon/Coronas-F teams, and T. Cline on behalf of the Konus-Wind team, and A. Rau, A. von Kienlin, G. Lichti on behalf of the INTEGRAL SPI-ACS GRB team report: On May 2 Konus-Wind detected two SGR-like bursts in the trigger mode. The first one triggered Konus-Wind at 5376.421 s UT (01:29:36.421). It was also detected by INTEGRAL SPI-ACS. Because the burst was soft, the SPI-ACS response is very weak, and precise triangulation of this burst is not possible. We conservatively estimated that the time delay was 3.6 +/- 0.4 s which is consistent with the expected time delay for SGR 1806-20 (=3.651 s). Additionaly, the Konus ecliptic latitude response indicates that the burst source is near the ecliptic plane, so we believe that this burst originated from SGR 1806-20. The burst is unusually long with a duration of ~4.5 s, but relatively weak. As observed by Konus-Wind, the burst had a fluence ~2.0x10^-5 erg/cm2, and a peak flux ~6x10^-6 erg/cm2 s (both in 20-200 keV range). The time-integrated spectrum of the burst is well fitted by the OTTB spectral model: dN/dE ~ E^{-1} exp(-E/kT) with kT = 18 +/- 1 keV, which is typical for this SGR. The second burst triggered Konus-Wind at 18502.741 s UT (05:08:22.741). As observed by Konus-Wind, it had a duration ~1 s, a fluence ~4.5x10^-6 erg/cm2, a peak flux ~3.7x10^-6 erg/cm2 s (both in 20-200 keV range). Another two SGR-like bursts (soft and short) were observed by Konus-Wind in the background mode at 5021 s UT (01:23:41) and 16740 s UT (04:39:00) (also on May 2). The last burst was also detected by Helicon-Corronas-F in the background mode. The estimated time delay is consistent with SGR 1806-20 position. The Konus ecliptic latitude response indicates that the source of all these bursts is near the ecliptic plane, so we suppose, that they are also originated from SGR 1806-20. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3545 SUBJECT: Konus-Wind observation of an intermediate burst from SGR 1806-20 DATE: 05/06/13 13:29:10 GMT FROM: Dmitry Frederiks at Ioffe Institute S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks on behalf of Konus-Wind and Helicon/Coronas-F teams, and T. Cline on behalf of the Konus-Wind team report: An SGR-like burst 050611 triggered Konus-Wind at 58099.759 s UT (16:08:19.759). It was detected and localized by HETE WXM (HETE trigger 3800). The HETE error box includes the position of SGR 1806-20, so we conclude that this burst originated from this SGR. The burst had a duration of ~2.3 sec, fluence (8.41 ± 0.12)10-6 erg/cm2, and peak flux on 16-ms time scale (8.6 ± 0.9)10-6 erg/cm2 s (both in 20-200 keV range). The time-integrated spectrum of the burst can be fitted by the OTTB spectral model: dN/dE ~ E^{-1} exp(-E/kT), with kT = 19 ± 1 keV. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4168 SUBJECT: SGR 1806-20: continued moderate activity seen with INTEGRAL DATE: 05/10/27 08:09:41 GMT FROM: Sandro Mereghetti at IASF/CNR S. Mereghetti (IASF-Milano), D. Gotz (SAP, Saclay), M. Beck (ISDC, Versoix), J. Borkowski (CAMK, Torun) on behalf of the IBAS Localization Team, and I.F. Mirabel (ESO) on behalf of the INTEGRAL Science Working Team report: The soft gamma-ray repeater SGR 1806-20 continues to be in an active bursting state. A few normal short bursts have been detected by IBAS in October 2005 (note that SGR 1806-20 was not observed continuously during this period; the INTEGRAL observation log can be found at http://intweb.esac.esa.int/ ). Burst times, approximate durations, and fluences (15-100 keV) measured with the IBIS/ISGRI instrument are reported below: Date and UT Duration (s) Fluence (erg cm-2) 2005-10-01T07:47:10 0.1 3E-8 2005-10-04T02:54:14 0.1 2E-8 2005-10-22T03:43:40 0.1 4E-8 2005-10-22T07:25:37 0.38 9E-7 2005-10-22T08:52:42 0.07 2E-8 2005-10-25T04:48:31 0.11 2E-8 The burst at 2005-10-22T08:52:42 was followed by a fainter peak 4.4 s later, lasting 0.04 s. We remind that the occurrence of SGR 1806-20 bursts detected with high signal to noise ratio is reported in real time with IBAS Alert Packets. See http://ibas.mi.iasf.cnr.it/ for an uptated table of all the IBAS Alerts and for information on how to receive the Alert Packets for soft repeaters and type I bursters. This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4310 SUBJECT: Possible resuming of the SGR 1806-20 activity DATE: 05/12/03 14:37:11 GMT FROM: Valentin Pal'shin at Ioffe Inst S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks on behalf of Konus-Wind, and T. Cline on behalf of the Konus-Wind team, Two SGR-like events were detected recently by the Konus-Wind. The first one triggered the Konus-Wind on December 1 at 35965.468 s UT (09:59:25.468) . It had a duration ~3.6 sec, a fluence ~2.0x10^-5 erg/cm2, a peak flux ~1.2x10^-5 erg/cm2 s (both in 20-200 keV range). The time-integrated spectrum of the burst is well fit by the OTTB spectral model: dN/dE ~ E^{-1} exp(-E/kT) with kT = 19.7 ± 0.6 keV, which is typical for SGR 1806-20. The second one occurred on December 3 at 32626.087 s UT (09:03:46.087) (only ~5 hours ago). It had an unusual long initial pulse with a duration ~9 sec followed by at least 9 weaker short bursts during the 229 sec of the Konus-Wind trigger record. So, this event can be classified as a burst series. The Konus-Wind spectral data for this event will be available in a day. The Konus ecliptic latitude response indicates that the source of these bursts is near the ecliptic plane. There were no solar flares at these times according to the GOES data. We suppose, that these events are originated from SGR 1806-20. But now we can not exclude the other possibilities. Further analysis using the data from other instruments will clarify this issue. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5427 SUBJECT: VLA Upper Limit on Outburst of SGR 1806-20 DATE: 06/08/09 13:14:36 GMT FROM: Jim Ulvestad at NRAO E. Fomalont, B. Clark, and J. Ulvestad report on behalf of NRAO: We have used the NRAO Very Large Array in its B configuration on behalf of the community for an observation of SGR 1806-20, the apparent source of GRB 060806 (GCN 5416, Hurley et al. 2006; GCN 5419, Hurley et al. 2006). The observation epoch was 2006AUG09 at 03:15 UT. There was no significant detection of a new point source at the nominal J2000 position of 18:08:39.4, -20:24:39.8 (Taylor et al. 2005, ApJL, 634, L93). The approximate 5-sigma upper limits for a new point source are as follows: 1.42 GHz: < 2.0 mJy (limited by confusion) 8.46 GHz: < 0.3 mJy 22.46 GHz: < 1.7 mJy The raw data will appear in the VLA archive at http://www.nrao.edu/archive/ at approximately 0:00:00 UT on 2006AUG10, and are freely available to the community for further processing and analysis. An additional community observation is planned for 2006AUG10 to check for a later appearance of a new point source. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. [GCN OPS NOTE(09aug06): This Circular was delayed 8 hours until the new account could be added to the list.] //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5438 SUBJECT: A dust-scattering halo detected around SGR 1806-20 DATE: 06/08/11 16:27:31 GMT FROM: Kim Page at U.of Leicester M.R Goad, K.L. Page, O. Godet, P.T. O'Brien, S. Vaughan (U Leicester), and K. Hurley (Berkeley) report on behalf of the Swift-XRT team: Analysis of 2.5 ks of Swift-XRT Photon Counting (PC) mode data taken approximately 31 hours after the latest outburst of SGR 1806-20 (Hurley et al., GCN Circ. 5419), reveals a dust-scattering halo, with a angular radius of approximately 120 arcseconds at this time. The halo is also detected in 14 ks of XRT PC mode data taken 93.5 hours after the burst. The measured size of the halo at this time, approximately 212 arcseconds, is consistent with theoretical predictions for the expansion of a dust scattering halo. There are a number of well-known molecular clouds in the direction of SGR 1806-20 (eg. Corbel et al. 1997, ApJ 478, 624), including the so-called expanding arm located at a distance of approximately 3 kpc. Using simple geometrical arguments (eg. Predehl et al. 2000, A&A, 357, L25), we place a firm upper limit on the distance to the dust scattering screen of 6.6 kpc. Adopting as a lower limit the estimated distance to SGR 1806-20 of 6 kpc (McClure-Griffiths and Gaensler 2005, ApJL 630, L161), then the dust scattering screen is located at approximately 3 kpc, consistent with an origin in the expanding Arm. If, however, we adopt a distance of 15 kpc for SGR 1806-20 (Corbel et al. 1997), then the dust scattering screen is located at ~4.5 kpc. Another Soft Gamma-ray Repeater, SGR 1900+14, has previously shown a dust halo (Kouveliotou et al. 2001, ApJ 558, L47). //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5439 SUBJECT: Second VLA limit on new radio point source in SGR 1806-20 DATE: 06/08/11 21:13:35 GMT FROM: Jim Ulvestad at NRAO E. Fomalont, B. Clark, and J. Ulvestad report on behalf of NRAO: We have used the NRAO Very Large Array in its B configuration on behalf of the community for a second observation of SGR 1806-20, the apparent source of GRB 060806 (GCN 5416, Hurley et al. 2006; GCN 5419, Hurley et al. 2006). As noted in GCN 5426 (Golenitskii et al. 2006), the gamma-ray activity is far below that of the large flare of December 2004. The observation epoch for the second VLA observation was 2006AUG11 at 06:10 UT, and there was no detection of a new radio point source at the location of SGR 1806-20. The approximate 5-sigma upper limit at 8.46 GHz was < 0.23 mJy, consistent with the value of < 0.30 mJy seen two days previously and reported by us in GCN 5427. This concludes the planned NRAO service observations of SGR 1806-20 in response to the recent outburst. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5440 SUBJECT: Image of the dust-scattering halo around SGR 1806-20 DATE: 06/08/12 08:31:07 GMT FROM: Kim Page at U.of Leicester K.L. Page (U. Leicester) & N. Gehrels (NASA/GSFC) report on behalf of the Swift-XRT team: As an addendum to yesterday's GCN Circular (number 5438) about the detection of a dust-scattering halo around SGR 1806-20, please find available an image of the expanding halo at: http://www.swift.ac.uk/SGR1806.shtml //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5490 SUBJECT: Two bright bursts from SGR 1806-20 detected with IBAS DATE: 06/08/30 15:48:59 GMT FROM: Diego Gotz at IASF-CNR D. Gotz (CEA, Saclay) and S. Mereghetti (IASF, Milano), on behalf of the IBAS Localization Team report: The INTEGRAL Burst Alert System (IBAS) has detected several bursts from SGR 1806-20 in the IBIS/ISGRI data, indicating that the source is in an active state. We report here the properties of the two brightest and longest bursts, that were detected on August 29, 2006, as well as the times of the other events detected in the last few days. The burst detected on Aug 29 at 21:57:43 UT was so bright to fully saturate the ISGRI telemetry share after about 1 s. This burst was also detected by the Anti-Coincidence System of the SPI instrument above ~80 keV, where it lasted 2 s. The 20-200 keV spectrum, derived from the the available IBIS/ISGRI data, can be fitted with a Thermal Bremsstrahlung (TB) model with a temperature of 22 keV. This is a typical value for the SGR 1806-20 bursts, but the lower limit on its fluence ( 7E-7 erg/cmsq, 15-100 keV) places this burst among the brightest detected with INTEGRAL (Gotz et al., 2006, A&A, 445, 313). The second burst was detected at 22:10:28 UT and lasted 1.2 s. In this case the telemetry was saturated only partially. The lower limit on the fluence is 1E-6 erg/cmsq, and the TB temperature is 19 keV. The times of all the recent IBAS triggers due to bursts from SGR 1806-20 are given below. For 15 of them automatic alert packets have been sent (see Alerts #3437-3452 at http://ibas.iasf-milano.inaf.it). 2006-08-19T05:57:48 2006-08-25T21:03:31 2006-08-26T02:13:37 2006-08-26T03:23:35 2006-08-26T04:13:22 2006-08-26T04:25:25 2006-08-26T12:32:55 2006-08-26T18:48:47 2006-08-26T22:07:52 2006-08-27T03:14:45 2006-08-27T04:20:10 2006-08-27T08:49:52 2006-08-27T12:25:26 2006-08-27T12:41:34 2006-08-28T13:38:31 2006-08-29T21:57:43 2006-08-29T22:10:28 2006-08-29T22:48:01 2006-08-30T03:16:47 2006-08-30T14:58:39 2006-08-30T15:11:34 INTEGRAL will continue to monitor regularly the region of the Galactic Centre (at least once every 3 days) until October 26th. This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6228 SUBJECT: long burst from SGR 1806-20 detected on March 26 DATE: 07/03/28 13:02:07 GMT FROM: Valentin Pal'shin at Ioffe Inst S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, and T. Cline on behalf of the Konus-Wind team, K. Yamaoka, T. Uehara, M. Ohno, Y. Fukazawa, T. Takahashi, M. Tashiro, Y. Terada, T. Murakami, and K. Makishima on behalf of the Suzaku WAM team, report: A bright long SGR-like event triggered the Konus-Wind at T0=1447.725 (00:24:07.725) on March 26. It was also detected by the Suzaku-WAM in the TRN mode. We have triangulated it to an annulus centered at RA(J2000) = 186.083 (12h 24m 20s) Dec(J2000)=+3.334 (+3d 20' 04"), whose radius is 87.186 +/- 1.090 deg (3 sigma). As the center line of this annulus passes 0.311 degrees (0.9 sigma) from the position of SGR 1806-20 and the Konus ecliptic latitude response indicates that the source of the burst is near the ecliptic plane, we believe that this burst originated from SGR 1806-20. The shape of the burst light curve is typical for SGR bursts, but with an unusually long duration. It demonstrates a fast rise and a ~8-s decay with a bump at T-T0 ~5 s. As observed by Konus-Wind the burst had a fluence 2.78(-0.08, +0.07)x10^-5 erg/cm2, and a peak flux on 16-ms time scale 2.01(-0.26, +0.25)x10^-5 erg/cm2 (both in the 20-200 keV range). The time-integrated spectrum of the burst can be fit by the OTTB spectral model: dN/dE ~ E^{-1} exp(-E/kT) with kT = 20.7 +/- 0.7 keV, which is typical for SGR 1806-20. All the quoted errors are at 90% c.l. The Konus-Wind light curve of this GRB can be seen at http://www.ioffe.rssi.ru/LEA/SGRs/070326_T01447/ A previous SGR burst triggered Konus-Wind on March 17 at T0=84623.793 s UT (23:30:23.793). It had a duration of ~4 sec. The burst was not localized, but since the Konus ecliptic latitude response indicates that the burst source is near the ecliptic plane, we believe that it also originated from SGR 1806-20. The longest burst from SGR 1806-20 (except the giant burst) had a duration of ~22 sec (Golenetskii et al., GCN 4312). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6239 SUBJECT: INTEGRAL ToO Observation of SGR1806-20 DATE: 07/04/02 17:03:03 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley, on behalf of the INTEGRAL AO-4 SGR ToO team, reports: In view of the recent activity of SGR1806-20 observed by Konus (GCN 6228), as well as a lower level of activity observed by Swift, we have called an INTEGRAL target of opportunity observation of this source. The start times and durations of the observations are: Start time, UT Duration (s) 2007-04-06 11:33:21.0 109728 2007-04-07 19:31:06.0 44577 2007-04-08 08:40:42.0 24003 2007-04-08 16:06:00.0 30861 We encourage supporting observations at all wavelengths. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6264 SUBJECT: Suzaku ToO observation of SGR 1806-20 DATE: 07/04/10 09:45:07 GMT FROM: Yujin E. Nakagawa at Aoyama Gakuin U Y. E. Nakagawa, K. Yamaoka, A. Yoshida, S. Sugita (Aoyama Gakuin U.), T. Mihara (RIKEN), M. Suzuki (ISAS/JAXA), T. Murakami, D. Yonetoku (Kanazawa U.), M. Nakajima (Nihon U.), M. Tashiro (Saitama U.), and K. Nakazawa (Univ. of Tokyo) report: The Suzaku ToO Observation was conducted on SGR 1806-20 with the narrow field instruments (XIS and HXD) from 15:08:00 on March 30 2007 to 01:30:19 on March 31. Its net exposure was about 20 ks. This object showed a long burst at 00:24:08 on March 26 2007 which was detected by the Konus-Wind and the Suzaku-WAM instruments (Golenetskii et al., GCN 6228). No bright burst was observable in the light curve during the ToO observation. The preliminary analyses showed that the flux of the steady emission in 2-10 keV was about 8.8 x 10^-12 ergs cm^2 s^-1. By the quick-look analyses with the XIS data, the average spectrum is well fitted by a single power-law model of the photon index of ~ 2.1 with an interstellar absorption column of ~ 7 x 10^22 cm^-2, as well as a two blackbody function is acceptable. We would like to thank the Suzaku team for the immediate ToO observation and the data processing. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6684 SUBJECT: Intense burst from SGR 1806-20 detected on July 27 DATE: 07/07/29 18:50:55 GMT FROM: Valentin Pal'shin at Ioffe Inst S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, and T. Cline on behalf of the Konus-Wind team, A. von Kienlin, G. Lichti, A. Rau, D. Gotz, and S. Mereghetti, on behalf of the INTEGRAL GRB team, K. Yamaoka, T. Uehara, M. Ohno, Y. Fukazawa, T. Takahashi, M. Tashiro, Y. Terada, T. Murakami, and K. Makishima on behalf of the Suzaku WAM team, K. Hurley, D. M. Smith, R. P. Lin, J. McTiernan, R. Schwartz, C. Wigger, W. Hajdas, and A. Zehnder, on behalf of the RHESSI GRB team, report: An intense short SGR-like event triggered Konus-Wind at 2007-07-27 T0=24046.498 s UT (06:40:46.498). It was also detected by INTEGRAL-SPI-ACS, RHESSI, and Suzaku-WAM in the TRN mode. We have triangulated this burst to Konus-SPI-ACS and Konus-RHESSI annuli, both of which are consistent with the position of SGR 1806-20. The Konus-SPI-ACS annulus is inconsistent with the positions of all other known SGRs. The Konus ecliptic latitude response indicates that the source of the burst is near the ecliptic plane. Thus we believe that this burst originated from SGR 1806-20. The burst had a duration of ~1 s. The Earth-crossing time of the onset was 24041 s UT (06:40:41). As observed by Konus-Wind the burst had a fluence of 9.14(-0.44, +0.36)x10^-6 erg/cm2, and a 16-ms peak flux measured from T0-0.050 s of (1.91 +/- 0.25)x10^-5 erg/cm2 (both in the 20-200 keV range). The spectrum of the burst (from T0 to T0+0.256) is well fitted (in the 20-200 keV range) by the OTTB spectral model: dN/dE ~ E^{-1} exp(-E/kT) with kT = 21.7 +/- 1.2 keV (chi2 = 25/20 dof). All the quoted errors are at 90% c.l. The Konus-Wind light curve of this burst is available at http://www.ioffe.rssi.ru/LEA/SGRs/070727_T24046/ The last burst from SGR 1806-20 to trigger Konus-Wind was on March 26 (Golenetskii et al., GCN 6228). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6688 SUBJECT: AGILE-ACS position for the SGR 1806-20 July 27 burst DATE: 07/07/30 16:25:36 GMT FROM: Sandro Mereghetti at IASF/CNR F.Perotti, A.Giuliani, S.Mereghetti, M.Fiorini, S.Vercellone, A.Chen, A.Pellizzoni (IASF-Milano), C.Labanti, M.Trifoglio, G.Di Cocco (IASF-Bologna), M.Tavani, M.Feroci, A.Argan, A.Trois (IASF-Roma), G.Picozza (INFN-Roma), F.Longo, G. Barbiellini (INFN-Trieste), on behalf of the AGILE Team and P. Giommi, L.A. Antonelli, C. Pittori (ASDC), and L. Salotti (ASI) report: The SGR-like burst detected on July 27 at about 06:41 UT with Konus/Wind, INTEGRAL-SPI-ACS, RHESSI and Suzaku-WAM (Golenetskii et al. GCN 6684), and likely associated to SGR 1806-20, has been seen also by the Anticoincidence system of AGILE. This segmented anticoincidence detector surrounds the gamma-ray tracker on five sides (top and 4 lateral). The relative intensity of the count rates measured from the different sides allows to estimate the arrival direction of the detected bursts. Based on a simple geometrical model, the detection of this event in two of the lateral panels and its non-detection in the top panel, yields an instrumental azimuthal angle within 3 degrees from that of SGR 1806-20. We thus support the association of this event with SGR 1806-20. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6804 SUBJECT: SGR1806-20: Swift-BAT detection of enhanced activity DATE: 07/09/19 21:29:28 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC), D. M. Palmer (LANL), T. Sakamoto (NASA/ORAU), G. Sato (GSFC/ISAS) and M. Stamatikos (NASA/ORAU) report on behalf of the Swift Team: At 20:45:10 UT, the Swift Burst Alert Telescope (BAT) triggered and located the SGR 1806-20 (trigger=291587). We note that the initial GCN Notice went out with a dual identification of this source (both SGR 1900+14 and SGR 1806-20). This is due to a mismatch error in the catalog numbers used between the on-board and ground catalogs for this source. The real identification is SGR 1806-20. We also note that because of a star tracker loss-of-lock error, the flight position is 10 arcmin off the true position. The BAT light curve shows a large initial spike of ~190,000 counts/sec with an ~2 sec FWZM, followed by 4 smaller spikes: ~2000 cnts/sec at ~T+3 sec, 10,000 cnts/sec at ~T+5 sec, 50,000 cnts/sec at ~T+14 sec, and 30,000 cnts/sec at ~T+18 sec. Swift-BAT, and other space instruments (e.g. Konus-WIND and Konus-A, Suzaku-WAM, IBAS, and SuperAGILE) have been detecting elevated activity from this source over the past few days. Notably, earlier today (at 16:01:12 UT, Trigger #291566) a 50,000 counts/second burst (250 times the flux of the Crab) was detected by BAT, which made it the third largest SGR 'baby' burst (excluding activity related to the superburst) imaged by the Swift mission. The new Trigger #291587 burst reported here is much larger. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6815 SUBJECT: INTEGRAL ToO observations of SGR1806-20 DATE: 07/09/21 23:23:49 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley, on behalf of the INTEGRAL Cycle 4 SGR ToO team, reports: In view of the continued activity of SGR1806-20, a 206 ks INTEGRAL Target of Opportunity observation of this source has been scheduled. The tentative observation times are: Start time Duration (s) 2007-09-30 00:06:42.0 106299 2007-10-01 07:04:45.0 48006 2007-10-01 21:20:21.0 24003 2007-10-02 04:42:45.0 27432 Any major changes to these times will be reported in a future GCN. Supporting observations at all wavelengths are encouraged. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6822 SUBJECT: Recent SGR1806-20 Activity DATE: 07/09/24 20:45:04 GMT FROM: Kevin Hurley at UCBerkeley/SSL S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, P. Oleynik, M. Ulanov and T. Cline, on behalf of the Konus-Wind and Konus-A teams, D. Palmer, S. Barthelmy, J. Cummings, N. Gehrels, and H. Krimm, on behalf of the Swift-BAT team, K. Hurley, A. von Kienlin, G. Lichti, A. Rau, D. Gotz, and S. Mereghetti, on behalf of the INTEGRAL GRB team, M. Feroci, P. Soffitta and Y. Evangelista, on behalf of the AGILE team, K. Yamaoka, M. Ohno, Y.E. Nakagawa, Y. Fukazawa, T. Takahashi, M. Tashiro, Y. Terada, T. Murakami, and K. Makishima, on behalf of the Suzaku WAM GRB team, report: SGR1806-20 has become very active since September 14 (Barthelmy et al. GCN 6804). The following is a partial list of bursts observed by some of the IPN spacecraft (some weaker IBIS events did not trigger the INTEGRAL Burst Alert Service). "Loc" means that the burst was localized by triangulation to at least a relatively narrow annulus, or by the Swift BAT or by IBIS. A "no" in this column means that the event has only been localized to a relatively wide ecliptic latitude band. INTEGRAL (GCN 6815) and Chandra target of opportunity observations of this source are planned, and we encourage supporting observations at all wavelengths. Date Time Fluence Observed by Loc 20-200 (at least) keV ------------------------------------------------------------------- 20070914 10:46:02 8.2E-7 BAT,IBIS,KW y 20070914 14:54:47 1.6E-5 KW,KA,SA y 20070914 14:58:44 1.0E-6 KW no 20070914 19:57:57 2.8E-6 BAT,KA y 20070914 21:03:36 4.5E-7 KW no 20070916 07:08:38 6.5E-7 IBIS,KW y 20070916 09:48:08 1.0E-6 IBIS,KW y 20070918 17:08:50 1.6E-5 KW,SA,SPI-ACS,SUZ y 20070919 10:01:51 1.5E-6 IBIS,KW y 20070919 15:13:04 6.5E-7 KW no 20070919 16:01:13 2.4E-6 BAT,KA,KW y 20070919 16:54:44 9.6E-7 KW no 20070919 19:34:50 9.0E-7 IBIS,KW y 20070919 20:45:10 ? BAT,IBIS y 20070920 04:30:11 1.9E-6 IBIS,KW y 20070921 07:11:59 1.4E-6 IBIS,KW y 20070921 11:45:35 4.0E-7 KW no 20070923 12:46:15 2.6E-6 KW,KA no ------------------------------------------------------------------ Some Abbreviations: BAT: Swift Burst Alert Telescope IBIS: Imager on Board the INTEGRAL Satellite KA: Konus-A (Cosmos 2421) KW: Konus-Wind SA: Super-AGILE SPI-ACS: Anticoincidence System of the INTEGRAL Spectrometer SUZ: Suzaku WAM //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8497 SUBJECT: SGR 1806-20: Fermi GBM detection DATE: 08/11/07 17:26:47 GMT FROM: Sheila McBreen at MPE Sheila McBreen (UCD/MPE) and Chryssa Kouveliotou (NASA/MSFC) report on behalf of the Fermi GBM Team: "At 05:47:04.08 UT on 06 November 2008, the Fermi Gamma-Ray Burst Monitor triggered on a soft, short event (trigger 247643225 / 081106241). The on-ground calculated location, using the GBM trigger data, is RA = 271.3, DEC = -16.2 (J2000 degrees, equivalent to 18 h 05 m, -16 d 12 '), with an uncertainty of 5.6 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error for soft localisations which is currently estimated to be 5 to 6 degrees). This position is consistent with SGR 1806-20. The angle from the Fermi LAT boresight is 41 degrees. The GBM light curve comprises a single peak with a duration of about 80 ms. The time-averaged spectrum from T0-0.045 s to T0+0.035 s is adequately fit by a simple power law function with index -2.13 +/- 0.08. (chi squared 205.1, for 242 d.o.f.) The event fluence (10-100 keV) in this time interval is (7.9 +/- 0.3)E-8 erg/cm^2. An optically thin thermal bremsstrahlung (OTTB) function fits the spectrum equally well (chi squared 203.9 for 242 d.o.f.) with kT = 36.5 +/-3.9 keV. The spectral analysis results presented above are preliminary, Final results will be published in the GBM Magnetar catalog." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22808 SUBJECT: GRB 180620A: Swift-XRT refined Analysis DATE: 18/06/20 17:03:02 GMT FROM: Phil Evans at U of Leicester A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), A. Tohuvavohu (PSU), S. J. LaPorte (PSU), J.A. Kennea (PSU), S.L. Gibson (U. Leicester), Z. Liu (NAOC / U. Leicester), J.P. Osborne (U. Leicester), P. D'Avanzo (INAF-OAB) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 9.6 ks of XRT data for GRB 180620A (Evans et al. GCN Circ. 22798), from 274 s to 23.4 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN Circ. 22802). The late-time light curve (from T0+6.1 ks) can be modelled with a power-law decay with a decay index of alpha=2.16 (+/-0.13). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.46 (+0.10, -0.08). The best-fitting absorption column is 1.76 (+0.43, -0.16) x 10^21 cm^-2, consistent with the Galactic value of 1.6 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.9 x 10^-11 (5.6 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.76 (+0.43, -0.16) x 10^21 cm^-2 Galactic foreground: 1.6 x 10^21 cm^-2 Excess significance: <1.6 sigma Photon index: 1.46 (+0.10, -0.08) If the light curve continues to decay with a power-law decay index of 2.16, the count rate at T+24 hours will be 2.3 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.1 x 10^-13 (1.3 x 10^-13) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00843122. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22811 SUBJECT: GRB 180620A: Xinglong-2.16m optical observations DATE: 18/06/20 19:20:31 GMT FROM: Dong Xu at NAOC/CAS Z.P. Zhu, D. Xu, J.B. Zhang (NAOC), X. Zhang, J.H. Liu (XAO) report We observed the field of GRB 180620A (Evans et al., GCN 22790) using the 2.16-m telescope located at Xinglong, Hebei, China, equipped with the BFOSC camera. We obtained 3x600s R-band frames, starting at 12:39:01 UT on 2018-06-20, i.e., 4.068 hrs after the BAT trigger. The GRB's optical afterglow (Evans et al., GCN 22790; Butler et al., GCN 22799; Elenin et al., GCN 22800; Tyurina et al., GCN 22801; Guidorzi et al., GCN 22803) is clearly detected in each frame. Preliminary photometry shows the afterglow has decayed to m(R)~20.0, calibrated with nearby USNO B1 stars. We acknowledge the excellent support from the Xinglong staff, particularly Xiao Feng and Huijuan Wang, in obtaining these observations. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22812 SUBJECT: GRB 180620A: KAIT Optical Observations DATE: 18/06/20 20:13:48 GMT FROM: Weikang Zheng at UC Berkeley WeiKang Zheng and Alex Filippenko (UC Berkeley) report on behalf of the KAIT GRB team: The 0.76-m Katzman Automatic Imaging Telescope (KAIT) at Lick Observatory responded to Swift GRB 180620A (Evans et al., GCN 22798) starting at 08:37:19 UT, 141s after the burst. Observations were performed with an automatic sequence in the V, I, and clear (roughly R) filters, and the exposure time was 20 s per image, observations lasted about 3 hours. The optical afterglow (Evans et al., GCN 22790; Butler et al., GCN 22799; Elenin et al., GCN 22800; Tyurina et al., GCN 22801; Guidorzi et al., GCN 22803; Breeveld et al., GCN 22805; Watson et al., GCN 22806; Zhu et al., GCN 22811) was well detected in our V, I and clear filter images. A preliminary analysis shows that the afterglow rises at early time and peaked around 300s (also seen by Butler et al. GCN 22799; Watson et al., GCN 22806). After that the light curve shows monotonic decay, followed by a flat phase between ~1ks to ~3ks. A preliminary light curve is posted at: http://astro.berkeley.edu/~zwk/grb/GRB180620A/GRB180620A_kait.png //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22813 SUBJECT: GRB 180620B: Fermi GBM detection DATE: 18/06/20 22:18:37 GMT FROM: Bagrat Mailyan at UAH B. Mailyan (UAH) reports on behalf of the Fermi GBM Team: "At 15:50:36.05 UT on 20 June 2018, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 180620B (trigger 551202641 / 180620660), which was also detected by the Swift/BAT and XRT (Evans et al. 2018, GCN 22807). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight at the GBM trigger time is 137 degrees. The GBM light curve shows multi-peaked structure with a duration (T90) of about 46.7 s (50-300 keV). Evans et al. 2018 report a shorter duration of ~30 s in the Swift/BAT. We suggest the discrepancy may be due to extended hard emission of this GRB. The time-averaged spectrum from T0 to T0+46 s is adequately fit a power law function with an exponential high-energy cutoff. The power law index is 0.85 +/- 0.1 and the cutoff energy, parameterized as Epeak, is 149 +/- 11 KeV. A Band function fits the spectrum equally well with Epeak= 106 +/- 15 keV, alpha = -0.5 +/- 0.2 and beta = -2.2 +/- 0.1. The event fluence (10-1000 keV) in this time interval is (7.7 +/- 0.04)E-06 erg/cm^2. The 1-s peak photon flux measured starting from T0 in the 10-1000 keV band is 6.8 +/- 0.5 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22814 SUBJECT: GRB 180620B: Enhanced Swift-XRT position DATE: 18/06/21 01:15:28 GMT FROM: Phil Evans at U of Leicester A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team. Using 3193 s of XRT Photon Counting mode data and 4 UVOT images for GRB 180620B, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 357.52122, -57.96243 which is equivalent to: RA (J2000): 23h 50m 5.09s Dec (J2000): -57d 57' 44.8" with an uncertainty of 1.4 arcsec (radius, 90% confidence). This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular was automatically generated, and is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22815 SUBJECT: GRB 180620A: Swift-BAT refined analysis DATE: 18/06/21 02:37:49 GMT FROM: Amy Lien at GSFC M. Stamatikos (OSU), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), P. A. Evans (U Leicester), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 180620A (trigger #843122) (Evans et al., GCN Circ. 22798). The BAT ground-calculated position is RA, Dec = 279.890, 23.239 deg which is RA(J2000) = 18h 39m 33.5s Dec(J2000) = +23d 14' 18.6" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 42%. The mask-weighted light curve shows a multi-peaked structure that starts at ~T-7 s and ends at ~T+37 s. The two main peaks occur at ~T+5 s and ~T+12 s, respectively. T90 (15-350 keV) is 23.16 +- 4.82 sec (estimated error including systematics). The time-averaged spectrum from T-6.92 to T+37.07 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.72 +- 0.05. The fluence in the 15-150 keV band is 5.8 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+4.47 sec in the 15-150 keV band is 7.7 +- 0.4 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/843122/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22817 SUBJECT: GRB 180620B: Swift-XRT refined Analysis DATE: 18/06/21 10:04:12 GMT FROM: Phil Evans at U of Leicester A. Melandri (INAF-OAB), S. J. LaPorte (PSU), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), Z. Liu (NAOC / U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 6.6 ks of XRT data for GRB 180620B (Evans et al. GCN Circ. 22807), from 89 s to 56.0 ks after the BAT trigger. The data comprise 237 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN Circ. 22814). The late-time light curve (from T0+4.3 ks) can be modelled with a power-law decay with a decay index of alpha=0.61 (+/-0.08). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.34 (+/-0.05). The best-fitting absorption column is 2.30 (+/-0.15) x 10^21 cm^-2, in excess of the Galactic value of 1.4 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.99 (+0.11, -0.10) and a best-fitting absorption column of 1.6 (+/-0.3) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.5 x 10^-11 (4.6 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.6 (+/-0.3) x 10^21 cm^-2 Galactic foreground: 1.4 x 10^20 cm^-2 Excess significance: 7.9 sigma Photon index: 1.99 (+0.11, -0.10) If the light curve continues to decay with a power-law decay index of 0.61, the count rate at T+24 hours will be 0.12 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.1 x 10^-12 (5.5 x 10^-12) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00843211. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22818 SUBJECT: GROND observations of GRB 180620A DATE: 18/06/21 11:16:12 GMT FROM: Patricia Schady at MPE/Swift Tassilo Schweyer and Patricia Schady (MPE Garching) report: We observed the field of GRB 180620A (Swift trigger 843211; Evans et al., GCN #22807) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla Observatory (Chile). Observations started at 04:35 UT on 2018-06-21, 20 hours after the GRB trigger. They were performed at an average seeing of 1.4" and at an average airmass of 1.7. We detect a faint point source consistent with the position of the reported X-ray and optical afterglow (Elenin et al., GCN #22800; Osborne et al., GCN #22802; Breeveld et al., GCN #22805). Based on a total exposures time of around 30mins we estimate the following AB magnitudes: g' = 23.9 +/- 0.1 mag r' = 23.4 +/- 0.1 mag i' = 23.1 +/- 0.1 mag z' > 23.2 mag J > 21.2 mag H > 20.5 mag K > 19.3 mag Given magnitudes are calibrated against PanSTARRS and 2MASS field stars and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.11 in the direction of the burst (Schlafly & Finkbeiner 2011). We thank Markus Rabus for the excellent support from La Silla. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22819 SUBJECT: GROND observations of GRB 180620B DATE: 18/06/21 11:18:56 GMT FROM: Patricia Schady at MPE/Swift Tassilo Schweyer and Patricia Schady (MPE Garching) report: We observed the field of GRB 180620B (Swift trigger 843211; Evans et al., GCN #22807) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla Observatory (Chile). Observations started at 05:06 UT on 2018-06-21, 13.3 hours after the GRB trigger. They were performed at an average seeing of 1.6" and at an average airmass of 1.5. We found a single, bright point source within the 1.4" Swift-XRT enhanced error circle reported by Beardmore et al. (GCN #22814) at RA (J2000.0) = 23:50:05.088 Dec (J2000.0) = -57:57:43.88 with an uncertainty of 0.14" in each coordinate. Based on a total exposure time of around 30mins we estimate the following AB magnitudes: g' = 21.3 +/- 0.1 mag r' = 20.8 +/- 0.1 mag i' = 20.4 +/- 0.1 mag z' = 20.3 +/- 0.1 mag J = 19.7 +/- 0.1 mag H = 19.6 +/- 0.2 mag K = 19.1 +/- 0.4 mag Given magnitudes are calibrated against GROND zeropoints as well as 2MASS field stars and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.01 in the direction of the burst (Schlafly & Finkbeiner 2011). We thank Markus Rabus for the excellent support from La Silla. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22821 SUBJECT: GRB 180620B: Swift-BAT refined analysis DATE: 18/06/22 00:45:20 GMT FROM: Amy Lien at GSFC T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), P. A. Evans (U Leicester), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU) (i.e. the Swift-BAT team): Using the data set from T-179 to T+843 sec from the recent telemetry downlink, we report further analysis of BAT GRB 180620B (trigger #843211) (Evans et al., GCN Circ. 22807). The BAT ground-calculated position is RA, Dec = 357.514, -57.954 deg which is RA(J2000) = 23h 50m 03.3s Dec(J2000) = -57d 57' 13.5" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 78%. The mask-weighted light curve shows a multi-peaked structure that starts at ~T-160 s and ends at ~T+160 s. The three main peaks occur at ~T0, ~T+40 s, and ~T+100 s, respectively. Note that because the event data are only available from ~T-180 s, there might be additional burst emission before the available event data range. T90 (15-350 keV) is 198.8 +- 27.4 sec (estimated error including systematics). The time-averaged spectrum from T-159.376 to T+162.428 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 1.30 +- 0.20, and Epeak of 123.9 +- 68.3 keV (chi squared 58.09 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 1.0 +- 0.03 x 10^-5 erg/cm2 and the 1-sec peak flux measured from T-0.33 sec in the 15-150 keV band is 3.6 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.60 +- 0.05 (chi squared 65.76 for 57 d.o.f.). All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/843211/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22823 SUBJECT: GRB 180620B: VLT/X-shooter redshift DATE: 18/06/22 13:02:56 GMT FROM: Maryam Arabsalmani at CEA Paris-Saclay L. Izzo (HETH/IAA-CSIC), M. Arabsalmani (CEA Saclay), D. B. Malesani (DAWN/NBI and DARK/NBI), K. Wiersema (Warwick), G. Pugliese (API/U. Amsterdam), S. D. Vergani (GEPI/Obs. Paris), A. de Ugarte Postigo (HETH/IAA-CSIC and DARK/NBI), K. E. Heintz (Univ. Iceland and DAWN/NBI), D.A. Kann (HETH/IAA-CSIC), P. Schady (MPE), N.R. Tanvir (Leicester), J.P.U. Fynbo (DAWN/NBI), C. C. Thoene (HETH/IAA-CSIC), J. Bolmer (MPE Garching), report on behalf of the Stargate Consortium: We observed the optical afterglow of GRB 180620B (Evans et al. GCN 22807; Schweyer & Schady GCN 22819) using the ESO Very Large Telescope (VLT) UT2 equipped with the X-shooter spectrograph. Spectroscopic observations started on 09:27 UT on 21 June 2018, i.e. 0.73 days after burst. In the resulting spectrum, we find a series of strong absorption lines that we identify as Fe II, Mg II, Mg I, Zn II, Cr II, Al II and Al III at a common redshift of 1.1175. At this redshift, we also detect emission lines of [O II], [Ne III] and Balmer lines. Both absorption and emission lines show velocity structure. The absorption profiles are broad and spread over more than 800 km/s in velocity space. We are grateful to the visiting observers, Jean-Christophe Loison and Pedro Machado, for giving up some of their observing time. We thank the ESO staff, Marcela Espinoza and Alain Smette, for excellent support. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22824 SUBJECT: Konus-Wind observation of GRB 180620A DATE: 18/06/22 15:25:50 GMT FROM: Dmitry Svinkin at Ioffe Institute D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, M. Ulanov, A. Tsvetkova, A. Lysenko, A. Kozlova, and T. Cline on behalf of the Konus-Wind team, report: The long-duration GRB 180620A (Swift-BAT detection: Evans et al., GCN Cric. 22798) triggered Konus-Wind at T0=30906.173 s UT (08:35:06.173). The burst light curve shows a multi-peaked structure which starts at ~T0-6.6 s and has a total duration of ~16 s. The emission is seen up to ~2 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB180620_T30906/ As observed by Konus-Wind, the burst had a fluence of 9.80(-1.02,+1.74)x10^-6 erg/cm2, and a 64-ms peak flux, measured from T0+7.504 s, of 2.69(-0.82,+0.94)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+8.448 s) is best fit in the 20 keV - 4 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -1.19(-0.14,+0.16), the high energy photon index beta = -3.09(-6.91,+0.63), the peak energy Ep = 164(-24,+29) keV (chi2 = 70/75 dof). All the quoted errors are at the 90% confidence level. All the quoted values are preliminary. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22825 SUBJECT: Konus-Wind observation of GRB 180620B DATE: 18/06/22 15:28:00 GMT FROM: Dmitry Svinkin at Ioffe Institute D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, M. Ulanov, A. Tsvetkova, A. Lysenko, A. Kozlova, and T. Cline on behalf of the Konus-Wind team, report: The long-duration GRB 180620B (Swift-BAT detection: Evans et al., GCN Circ. 22807; Fermi-GBM detection: Mailyan, GCN Circ. 22813) triggered Konus-Wind at T0=57039.332 s UT (15:50:39.332). The burst light curve shows a multi-peaked structure which starts at ~T0-156 s and has a total duration of ~260 s. The emission is seen up to 0.8 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB180620_T57039/ As observed by Konus-Wind, the burst had a fluence of 1.19(-0.12,+0.14)x10^-5 erg/cm2, and a 64-ms peak flux, measured from T0-0.056 s, of 1.52(-0.61,+0.72)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The spectrum integrated over the most intense part of the burst (measured from T0 to T0+49.408 s) is best fit in the 20 keV - 2 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -1.04(-0.31,+0.36) and Ep = 118(-16,+23) keV (chi2 = 44/57 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.7 (chi2 = 44/56 dof). The spectrum near the maximum count rate (measured from T0 to T0+8.448 s) is best fit in the 20 keV - 2 MeV range by a power law with exponential cutoff model: with alpha = -0.74(-0.33,+0.37) and Ep = 129(-15,+21) keV (chi2 = 66/57 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.7 (chi2 = 66/56 dof). Assuming the redshift z=1.1175 (Izzo et al., GCN Circ. 22823) and a standard cosmology model with H_0 = 70 km/s/Mpc, Omega_M = 0.27, and Omega_Lambda = 0.73, we estimate the following rest-frame parameters: the isotropic energy release E_iso is ~3.9x10^52 erg, the peak luminosity L_iso is ~1.0x10^52 erg/s, and the rest-frame peak energy of the time-integrated spectrum, Ep,i, is ~273 keV. All the quoted errors are at the 90% confidence level. All the quoted values are preliminary. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22826 SUBJECT: GRB 180620A iTelescope observation DATE: 18/06/23 09:36:13 GMT FROM: Takanori Sakamoto at AGU M. Nakamura, T. Sakamoto (AGU) We observed the field of GRB 180620A detected by Swift (Evans et al., GCN Circ. 22798) with the iTelescope.Net (http://www.itelescope.net) T11 (Planewave 20") telescope located at the New Mexico Skies Observatory (NM, USA). 20 images of 60 sec exposures were taken in the R filter starting from June 20 on 10:11:01 (UT) about 1.6 hours after the trigger and stopped on 10:44:55 (UT). Due to the tracking issue of the telescope, we only obtained nine good quality images. We do not detect the optical afterglow both in the individual images and the stacked image at the UVOT position (Evans et al., GCN Circ. 22798). The estimated five sigma upper limit of the combined image (total exposure of 540 sec) is ~18.1 using the USNO-B1 catalog. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22827 SUBJECT: GRB 180620B: Swift/UVOT Detection DATE: 18/06/23 11:44:09 GMT FROM: Alice Breeveld at MSSL-UCL A. A. Breeveld (UCL-MSSL), P. A. Evans (U. Leicester) and M. De Pasquale (U. Instanbul) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 180620B 92 s after the BAT trigger (Evans et al., GCN Circ. 22807). A source consistent with the enhanced XRT position (Beardmore et al., GCN Circ. 22814) and the Grond position (Schweyer and Schady, GCN Circ. 22819), and also detected by Izzo et al. (GCN Circ. 22823) is detected in the initial UVOT exposures in all filters except uvw2. The non-detection in the uvw2 filter is consistent with the redshift of 1.12 (Izzo et al. GCN Circ. 22823). Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 92 242 147 18.06 ± 0.08 v 634 826 39 17.41 ± 0.22 b 559 579 20 17.56 ± 0.18 u 304 554 246 17.40 ± 0.09 uvw1 9950 18219 1394 20.17 ± 0.2 uvm2 6563 16382 804 20.6 ± 0.3 uvw2 4256 4443 183 > 19.7 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.01 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22843 SUBJECT: GRB 180620A: AstroSat CZTI detection DATE: 18/06/25 15:56:07 GMT FROM: Vidushi Sharma at IUCAA V. Sharma and D. Bhattacharya (IUCAA), V. Bhalerao (IIT-B), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the Astrosat CZTI collaboration: Analysis of Astrosat CZTI data showed the detection of a long GRB 180620A, which was also detected by Swift (Evans P. A. et al., GCN 22798) and Konus-Wind (D. Svinkin D. et al., GCN 22824). The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks of emission with strongest peak at 08:35:08.5 UT. The measured peak count rate is 287.9 cts/s above the background in combined data of four quadrants, with a total of 2046 cts. The local mean background count rate was 503 cts/s. Using cumulative rates, we measure a T90 of 14.8 s. It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22844 SUBJECT: GRB 180620B: AstroSat CZTI detection DATE: 18/06/25 15:56:59 GMT FROM: Vidushi Sharma at IUCAA V. Sharma, A. Vibhute and D. Bhattacharya (IUCAA), V. Bhalerao (IIT-B), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the Astrosat CZTI collaboration: Analysis of Astrosat CZTI data showed the detection of a long GRB 180620B, which was also detected by Swift (Evans P. A. et al., GCN 22807), Fermi-GBM (Mailyan B. et al., GCN 22813), Konus-Wind (Svinkin D. et al., GCN 22825). The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks of emission with strongest peak at 15:50:37.5 UT. The measured peak count rate is 259.6 cts/s above the background in combined data of four quadrants, with a total of 2643 cts. The local mean background count rate was 582.3 cts/s. Using cumulative rates, we measure a T90 of 22.3 s. It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25671 SUBJECT: GRB 180620A: SEDM Observations DATE: 19/09/05 22:46:33 GMT FROM: Virginia Cunningham at U of MD V. Cunningham (U of Maryland), J. D. Neill (Caltech), S. B. Cenko (NASA GSFC), and R. Walters (Caltech) report on behalf of the SEDM team: We observed the optical counterpart to GRB 180620A (Evans, et al., GCN 22798) with the Spectral Energy Distribution Machine (SEDM) on the 60 inch telescope at Palomar Observatory. The SEDM is a low resolution (R ~ 100) integral field unit spectrometer with a multi- band (ugri) rainbow camera imager (see Blagorodnova et al. 2018, PASP, 130, 035003, and Rigault et al. 2019, A&A, 627, A115). The SEDM began observing the optical counterpart at 9:37:37 UTC (63 minutes after the burst trigger time). We performed 2 x 1200 s exposures over the wavelength range 3800-9200 A. The continuum emission is well-fit by a power law spectrum with index alpha = 1.4 (f_nu ~ nu^-alpha). We do not confidently identify any obvious emission or absorption features in the spectrum.