The ATELs on this object have been copied into this list of Circulars for the convenience of the readers. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8112 SUBJECT: GRB 080822: Swift detection of a short burst DATE: 08/08/22 13:08:50 GMT FROM: Scott Barthelmy at NASA/GSFC S. T. Holland (CRESST/USRA/GSFC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester), D. N. Burrows (PSU), J. R. Cummings (NASA/UMBC), P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), O. Godet (U Leicester), C. Guidorzi (INAF-OAB), J. A. Kennea (PSU), V. Mangano (INAF-IASFPA), J. Mao (INAF-OAB), F. E. Marshall (NASA/GSFC), P. T. O'Brien (U Leicester), J. P. Osborne (U Leicester), C. Pagani (PSU), K. L. Page (U Leicester), D. M. Palmer (LANL), M. Perri (ASDC), T. Sakamoto (NASA/UMBC), B. Sbarufatti (INAF-IASFPA), R. L. C. Starling (U Leicester), G. Stratta (ASDC) and T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team: At 12:41:59 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 080822 (trigger=321174). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 75.270, +45.272 which is RA(J2000) = 05h 01m 05s Dec(J2000) = +45d 16' 20" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a single spike with a duration of less than 128 msec. The peak count rate was ~10000 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 12:43:16.3 UT, 77.1 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source with an enhanced position: RA, Dec 75.27800, 45.27623 which is equivalent to: RA(J2000) = 05h 01m 6.72s Dec(J2000) = +45d 16' 34.4" with an uncertainty of 2.6 arcseconds (radius, 90% containment). This location is 25 arcseconds from the BAT onboard position, within the BAT error circle. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (5.22e+21 cm^-2, Kalberla et al. 2005), with an excess column of 3.6 (+3.64/-2.95) x 10^21 cm^-2 (90% confidence). UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm) filter starting 83 seconds after the BAT trigger. No afterglow candidate is apparent in the initial data products. The TDRSS source list covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) = 1.29 mag. We note that the XRT position is 10.8 arcsec from the catalog position of the ROSAT source 2RXP J050107.7+451637. Burst Advocate for this burst is S. T. Holland (sholland AT milkyway.gsfc.nasa.gov). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8113 SUBJECT: New Soft Gamma Repeater 0501+4516 was GRB 080822 DATE: 08/08/22 13:30:44 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC), A. P. Beardmore (U Leicester), D. N. Burrows (PSU), J. R. Cummings (NASA/UMBC), N. Gehrels (NASA/GSFC), C. Guidorzi (INAF-OAB), S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU), J. Mao (INAF-OAB), F. E. Marshall (NASA/GSFC), C. Pagani (PSU), D. M. Palmer (LANL), M. Perri (ASDC), T. Sakamoto (NASA/UMBC), T. N. Ukwatta (GSFC/GWU) and L. Vetere (PSU) report on behalf of the Swift Team: At 13:12:52 UT, the Swift Burst Alert Telescope (BAT) triggered and located a second outburst from a new SGR source 0501+4516 (trigger=321177) which was previously reported as GRB 080822 (Holland et al, GCN Circ 8112). Swift was already looking at this location from the trigger on this source of ~30 min earlier. The BAT on-board calculated location is RA, Dec 75.265, +45.272, which is RA(J2000) = 05h 01m 04s Dec(J2000) = +45d 16' 20" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a single spike with a duration of less than 128 msec. The peak count rate was ~17000 counts/sec (15-350 keV), at ~0 sec after the trigger. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8114 SUBJECT: GRB 080822 (SGR 0501+4516): archival optical observations DATE: 08/08/22 17:49:29 GMT FROM: Denis Denissenko at IKI, Moscow D. V. Denisenko (Space Research Institute, Moscow, Russia) reports: Analysis of the Palomar Observatory Sky Survey plates available at http://archive.stsci.edu/cgi-bin/dss_plate_finder has revealed a variable object at the following position: RA (J2000.0) = 05 01 06.47 Dec (J2000.0) = +45 16 28.0 with an uncertainty of 0.2". This is 7" from the XRT position of GRB 080822 reported by Holland et al. (GCN 8112), thus formally outside the reported 90% error circle with the radius of 2.6". The above mentioned star is present in USNO-B1.0 catalogue as USNO-B1 1352-0128683 (RA = 05 01 06.42, Dec = +45 16 27.6) with the following magnitudes: B1=19.11, R1=15.99, B2=17.74, R2=15.97, I=16.52. Animation of two Blue and two Red plates, as well as color-combined (BRIR) images covering 101"x101" area around the variable star are available at . It should be also noted that the variable object is located 16" from the ROSAT source 1RXS J050107.9+451631 (catalog position error 13") with the hardness ratios HR1=0.96+/-0.08, HR2=1.00+/-0.12. These values are typical for X-ray binaries, including X-ray transients. Thus, the variable star is most likely associated with the ROSAT source. The optical spectroscopy of this star is encouraged. Also the follow-up X-ray observations of SGR 0501+4846 are required to reveal its true nature, improve the position accuracy and check the possible identification. This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8115 SUBJECT: Third event from SGR 0501+4516 DATE: 08/08/22 17:50:14 GMT FROM: Scott Barthelmy at NASA/GSFC D.M. Palmer (LANL) and S.D. Barthelmy (GSFC) report on behalf of the Swift Team: At 17:29:30 UT, the Swift Burst Alert Telescope (BAT) triggered and located a third outburst from SGR 0501+4516 (trigger=321252). Swift was already observing this source (from the previous triggers, GCNs 8112 and 8113). The BAT light curve again shows a single spike with a duration less than 128 msec. The peak count rate was ~4000 counts/sec (15-350 keV), at ~0 sec after the trigger. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8118 SUBJECT: Discovery of the Spin Period of the New Soft Gamma Repeater SGR 0501+4516 DATE: 08/08/22 21:39:33 GMT FROM: Chryssa Kouveliotou at MSFC E. Gogus (Sabanci University), P. Woods (Dynetics), and C. Kouveliotou (NASA/MSFC), report on behalf of a larger collaboration: We triggered our SGR ToO Program with RXTE following the Swift detection of a burst from the new Soft Gamma Repeater SGR 0501+4516 (Barthelmy et al. 2008, GCN # 8113). A 600 s RXTE observation started on 2008 August 22, 16:39:09 UT. During this pointing we detected one short SGR burst-like event in the PCA data (2-60 keV), confirming that the new source was in the field of view. We searched for a spin period for the new SGR in the 2.5-13.5 keV band PCA event mode data and detected a coherent signal (barycenter corrected) at 0.17334 Hz, corresponding to a spin period of 5.769 +- 0.004 s. A longer RXTE observation of SGR 0501+4516 is currently underway. We thank the RXTE planner, Divya Pereira, for prompt scheduling. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8119 SUBJECT: SGR 0501+4516: Swift-BAT refined analysis of the 3 discovery events DATE: 08/08/22 23:43:21 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC), N. Gehrels (GSFC), S. T. Holland (CRESST/USRA/GSFC), D. Palmer (LANL), T. Sakamoto (GSFC/UMBC) (for the Swift-BAT team): We report further analysis of three events from SGR 0501+4516 (triggers 321174, 321177, & 321252; GCN Circs. 8112, 8113, & 8115, repect; and ATEL 1676). We used data sets from T-2min to T+3min around each of the 3 trigger times. The BAT ground-calculated combined position is RA, Dec = 75.264, 45.271 deg, which is RA(J2000) = 05h 01m 06.4s Dec(J2000) = +45d 16' 17.1" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial codings were 67%, 100%, and 100%, respectively. Trigger 312174: The mask-weighted light curve shows a roughly triangular shaped peak with the rise time slightly slower than the fall time. T90 (15-350 keV) is 0.080 +- 0.014 sec (estimated error including systematics). The time-averaged spectrum from T-0.0 to T+0.1 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index -1.99 +- 0.01, and Epeak of 35.3 +- 2.0 keV (chi squared 65.4 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 6.5 +- 0.5 x 10^-8 erg/cm2 and the 1-sec peak flux measured from T-0.47 sec in the 15-150 keV band is 11.8 +- 1.0 ph/cm2/sec. A fit to a simple power law gives a photon index of 2.43 +- 0.5 (chi squared 134 for 57 d.o.f.). Trigger 312177: The mask-weighted light curve shows a FRED peak with T_rise about 2 msec and T_decay about 20 msec. There is a small peak riding on the decay tail. T90 (15-350 keV) is 0.072 +- 0.018 sec (estimated error including systematics). The time-averaged spectrum from T-0.0 to T+0.1 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.04 +- 0.49, and Epeak of 29.6 +- 3.3 keV (chi squared 69.3 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 6.7 +- 0.4 x 10^-8 erg/cm2 and the 1-sec peak flux measured from T-0.47 sec in the 15-150 keV band is 11.9 +- 0.8 ph/cm2/sec. A fit to a simple power law gives a photon index of 3.39 +- 0.5 (chi squared 239 for 57 d.o.f.). Trigger 312252: The mask-weighted light curve shows two slightly overlapping triangular shaped peaks. T90 (15-350 keV) is 0.060 +- 0.014 sec (estimated error including systematics). The time-averaged spectrum from T+0.0 to T+0.1 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.00 +- 1.35, and Epeak of 48.9 +- 10.5 keV (chi squared 54.4 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 1.4 +- 0.3 x 10^-8 erg/cm2 and the 1-sec peak flux measured from T-0.45 sec in the 15-150 keV band is 2.9 +- 0.5 ph/cm2/sec. A fit to a simple power law gives a photon index of 2.06 +- 0.25 (chi squared 64.5 for 57 d.o.f.). All the quoted errors are at the 90% confidence level. We note that there were many spike-like pulsed events in the BAT data around the time spanning these three events that were not sufficently strong to yield successful triggers in the on-board processing. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/321174/BA/ http://gcn.gsfc.nasa.gov/notices_s/321177/BA/ http://gcn.gsfc.nasa.gov/notices_s/321252/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8120 SUBJECT: Swift Trigger 321481: A Large Flare from SGR 0501+4516 DATE: 08/08/23 05:16:41 GMT FROM: David Palmer at LANL H. A. Krimm (CRESST/GSFC/USRA), D. M. Palmer (LANL), M. Perri (ASDC), B. Preger (ASDC), M. Stamatikos (NASA/ORAU) and L. Vetere (PSU) report on behalf of the Swift Team: At 04:47:48 UT, the Swift Burst Alert Telescope (BAT) triggered and located a large flare from the newly-discovered SGR 0501+4516 (GCN 8113, Barthelmy et al.; trigger=321481). Swift was pointed at the source at the time of the outburst. The BAT on-board calculated location is RA, Dec 75.270, +45.278 which is RA(J2000) = 05h 01m 05s Dec(J2000) = +45d 16' 41" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single spike of duration < 0.128 sec with a second smaller spike 0.5 sec later. The peak count rate was ~175000 counts/sec (15-350 keV), at ~0 sec after the trigger. There is no obvious 'ringing' at the SGR's rotation frequency following the burst, but this may be found in further analysis. Because this was identified onboard as a known source, it did not result in a GRB response with XRT and UVOT data immediately available through TDRSS. However, both instruments were observing the source at the time of the flare, and will return data through Malindi. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8121 SUBJECT: SGR 0501+4516: optical observations DATE: 08/08/23 06:50:50 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia A. de Ugarte Postigo (ESO Santiago & IAA-CSIC Granada), A. J. Castro-Tirado (IAA-CSIC Granada), J. M. Corral-Santana and J. Casares (IAC La Laguna), J. Blomme (Katholieke Univ. Leuven), P. Kubánek, M. Jelínek and J. Gorosabel (IAA-CSIC), report: "Following the discovery of the new soft gamma-ray repeater SGR 0501+4516 by SWIFT (Holland et al. GCNC 8112, Barthelmy et al. GCNC 8113), we have observed the field starting on Aug 23 (since 01:45 UT) with different telescopes/instruments on Spanish ground-based observatories: 0.6m BOOTES-2 (Z-band), 1.2m Mercator Telescope (Ic-band) and 2.5m Isaac Newton Telescope (r' & i' -bands). No optical counterpart within the reported Swift XRT error box is detected on the first r'-band image obtained on Aug 23, 02:49 UT (high airmass, limiting magnitude r'~21.5). We notice that some of the later images overlap in time with the large gamma-ray flare reported by Krimm et al. (GCN 8120) with null detection as a preliminary result once we have inspected by eye the whole BAT error box. Further analysis is on going". This message can be quoted. [GCN OPS NOTE(23aug08): Per author's request, "J. Corral" was replaced with "J. M. Corral-Santana" in the author list.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8122 SUBJECT: New Soft Gamma Repeater 0501+4516 (GRB 080822): GLAST Burst Monitor detection DATE: 08/08/23 10:01:50 GMT FROM: Andreas von Kienlin at MPE Andreas von Kienlin (MPE), N.P. Bhat (UAH), E. Bissaldi (MPE), M.S. Briggs (UAH), V. Connaughton (UAH), R. Diehl (MPE), G.J. Fishman (NASA/MSFC), L. Gibby (NASA/MSFC), J. Greiner (MPE), A.S. Hoover (LANL), A.J. van der Horst (NASA/ORAU), R.M. Kippen (LANL), C. Kouveliotou (NASA/MSFC), G.G. Lichti (MPE), C.A. Meegan (NASA/MSFC), S. McBreen (MPE), W.S. Paciesas (UAH), R.D. Preece (UAH), H. Steinle (MPE), M.S. Wallace (LANL), and C.A. Wilson-Hodge (NASA/MSFC)report: "At 12:41:59 UT on 2008 Aug 22, the GLAST Burst Monitor (GBM) triggered on the new Soft Gamma Repeater 0501+4516 (GRB 080822) (GBM 080822.529 / trigger 241101720), reported by SWIFT (Holland et al., GCN Circ. 8112, Barthelmy et al, GCN Circ. 8113 and GCN Circ. 8119). The on-ground calculated location, using the GBM trigger data, is RA = 86.2, Dec = +43.5 (J2000 degrees),(equivalent to J2000 05h 45m, +43d 30'), with an uncertainty of 3.3 degrees (radius, 1-sigma containment, statistical only). The true location error is 8.0 degrees for this soft, short event. This event has a duration of about 80 ms. The spectrum in the 10 keV to 100 keV energy band is well fit by a power law function with an index of -1.6 +/-0.1. The high temperature for an optically thin thermal bremsstrahlung (OTTB) fit is: 71 +/-13 keV. These results are consistent with the trigger clearly being seen to 100 keV. The spectral analysis results presented above are preliminary." //////////////////////////////////////////////////////////////////////// ATEL #1675 ATEL #1675 Title: SGR 0501+4516: Comparison with ROSAT archival data Author: J. A. Kennea (PSU) and V. Mangano (INAF-IASF PA) Queries: kennea@astro.psu.edu Posted: 22 Aug 2008; 20:32 UT Subjects: X-ray, Gamma Ray, Gamma-Ray Bursts, Transients We have analyzed an archival ROSAT observation of the newly discovered soft Gamma-ray repeater SGR 0501+4516 (GCN #8112, #8113, #8114, #8115). The ROSAT PSPC observed the a field containing SGR 0501+4516 between September 21st and 24th, 1992 for a total exposure time of 4.2 ks. An off-axis point source, 2RXP J050107.7+451637, was clearly detected in the observation which is coincident within errors the XRT position of the SGR. We have extracted the 0.2-2.4 keV spectrum of 2RXP J050107.7+451637, and compared it with the Swift/XRT spectrum from the first orbit of observations after the initial BAT trigger on SGR 0501+4516. Performing a simultaneous fit to both spectra, utilizing an absorbed power-law model and allowing the normalization to be independent for the two spectra, we find that both spectra are well fit (reduced chi2 = 0.9 for 47 degrees of freedom) by the following model parameters: N_H = (0.65 +/- 0.18) x 1022 cm-2 Photon Index = 1.7 +/- 0.3 The flux, uncorrected for absorption in the ROSAT band (0.2-2.4 keV) is 1.6 x 10-12 erg/s/cm2 for the ROSAT source, and 2.8 x 10-11 erg/s/cm2 for the XRT source. Assuming that these two sources are indeed the same object, the XRT detection is approximately a factor of 6 brighter than in the ROSAT detection. The ROSAT light curve does not show any obvious signs of variability. We therefore suggest on the basis of the positional coincidence and spectral similarity that 2RXP J050107.7+451637 is emission from SGR 0501+4516 in quiescence. We note also that a ROSAT All-Sky Survey detected source, 1RXS J050107.9+451631, is positionally coincident and has consistent flux with 2RXP J050107.7+451637, so is likely the same source. //////////////////////////////////////////////////////////////////////// ATEL #1676 ATEL #1676 Title: New Soft Gamma Repeater SGR 0501+4516 Author: S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester), D. N. Burrows (PSU), J. R. Cummings (NASA/UMBC), P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), O. Godet (U Leicester), C. Guidorzi (INAF-OAB), S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU), V. Mangano (INAF-IASFPA), J. Mao (INAF-OAB), F. E. Marshall (NASA/GSFC), P. T. O'Brien (U Leicester), J. P. Osborne (U Leicester), C. Pagani (PSU), K. L. Page (U Leicester), D. M. Palmer (LANL), M. Perri (ASDC), T. Sakamoto (NASA/UMBC), B. Sbarufatti (INAF-IASFPA), R. L. C. Starling (U Leicester), G. Stratta (ASDC), T. N. Ukwatta (GSFC/GWU), and L. Vetere (PSU) Queries: palmer@lanl.gov Posted: 22 Aug 2008; 21:04 UT Subjects: Soft Gamma-ray Repeaters The Authors report on behalf of the Swift Team: On 2008-08-22, at 12:41:59, 13:09:04 UT, 13:12:52, and 17:29:29, Swift-BAT triggered on four short (less than 128 ms) bursts of soft gamma-rays (no significant flux above 100 keV) with an afterglow located by XRT at: ??RA(J2000) ?= 05h 01m 6.78s ??Dec(J2000) = +45d 16' 34.0" with an uncertainty of 2.6 arcseconds (radius, 90% containment). (GCN 8112, Holland et al.; GCN 8113, Barthelmy et al.; GCN 8115, Palmer & Barthelmy) The repetition, the short, soft nature of the pulses, and the proximity of the source to the Galactic plane allow us to identify this source as a previously unknown Soft Gamma Repeater: SGR 0501+4516. The ROSAT source 1RXS J050107.9+451631, with a catalogued location 12.2 arcsec from the SGR location and a 13 arcsec uncertainty, may be a previous detection of quiescent flux from this object. //////////////////////////////////////////////////////////////////////// ATEL #1677 ATEL #1677 Title: Spin Period of New Soft Gamma Repeater SGR 0501+4516 Author: E. Gogus (Sabanci Univ.), P. Woods (Dynetics), & C. Kouveliotou (NASA/MSFC), on behalf of a larger collaboration: Queries: ersing@sabanciuniv.edu Posted: 22 Aug 2008; 21:21 UT Subjects: X-ray, Pulsars, Soft Gamma-ray Repeaters We triggered our SGR ToO Program with RXTE following the Swift detection of a burst from the new Soft Gamma Repeater SGR 0501+4516 (Barthelmy et al. 2008, GCN # 8113). A 600 s RXTE observation started on 2008 August 22, 16:39:09 UT. During this pointing we detected one short SGR burst-like event in the PCA data (2-60 keV), confirming that the new source was in the field of view. We searched for a spin period for the new SGR in the 2.5-13.5 keV band PCA event mode data and detected a coherent signal (barycenter corrected) at 0.17334 Hz, corresponding to a spin period of 5.769 ? 0.004 s. A longer RXTE observation of SGR 0501+4516 is currently underway. We thank RXTE planner, Divya Pereira for prompt scheduling. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8124 SUBJECT: Trigger 321551: Continued Large Flaring of SGR 0501+4516 DATE: 08/08/23 11:56:13 GMT FROM: David Palmer at LANL N. Gehrels (NASA/GSFC), J. Mao (INAF-OAB), D. M. Palmer (LANL), M. Perri (ASDC), B. Preger (ASDC), G. Stratta (ASDC) and L. Vetere (PSU) report on behalf of the Swift Team: At 11:27:35 UT, the Swift Burst Alert Telescope (BAT) triggered on a large flare from the newly discovered SGR 0501+4516 (trigger=321551). Swift was already observing this source location due to a previous trigger on this source. The BAT on-board calculated location is RA, Dec 75.265, +45.281 which is RA(J2000) = 05h 01m 04s Dec(J2000) = +45d 16' 52" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a roughly flat-topped structure with a duration of about 0.256 sec. The peak count rate was ~300k counts/sec (15-350 keV), at ~0.2 sec after the trigger. The BAT burst response algorithm causes a TDRSS alert only when a known source exceeds twice its previous fluence, so additional large flares may have occurred since the previously-reported large flare at 4:47:48 UT. Ground processing of Malindi data will be required to report on other activity by this source. [GCN OPS NOTE(25aug08): Per author's request, the end of the second sentence was changed from "...due to its previous." to "...due to a previous trigger on this source.".] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8125 SUBJECT: SGR 0501+4516: WSRT Radio Observations DATE: 08/08/23 17:55:23 GMT FROM: Alexander van der Horst at NASA/MSFC A.J. van der Horst (NASA/ORAU) and C. Kouveliotou (NASA/MSFC) report on behalf of a large collaboration: "We observed the position of the new SGR 0501+4516 (GCN 8112, 8113) at 4.8 GHz with the Westerbork Synthesis Radio Telescope at August 23 03.66 UT to 09.49 UT. We do not detect a radio source at the Swift XRT position (GCN 8112). The three-sigma rms noise in the map around that position is 99 microJy per beam. The formal flux measurement for a point source at that location is 13 +/- 33 microJy. We would like to thank the WSRT staff for promptly scheduling and obtaining these observations." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8126 SUBJECT: SGR 0501+4516: UKIRT detection of possible infra-red counterpart DATE: 08/08/23 18:22:54 GMT FROM: Nial Tanvir at IofA U.Cambridge N. R. Tanvir (U. Leicester), W. Varricatt (JACH) report on behalf of a larger collaboration: We observed the field of SGR 0501+4516 with UKIRT/UFTI about 2 hours after the first BAT trigger (Holland et al. GCN 8112). We clearly detect a faint point source in the K-band image within the XRT error circle, at a position, relative to 2MASS stars in the field, of: 05:01:06.75 +45:16:34.0 (J2000) with an uncertainty of about 0.5 arcsec. The magnitude of the source is K~18.6 (also calibrated to 2MASS) and there is tentative evidence of variability at the 0.2 mag level between sub-exposures, supporting the possibility that it is the nIR counterpart to the SGR. Further analysis is ongoing. //////////////////////////////////////////////////////////////////////// Continued Activity of SGR 0501+4516 ATel #1678; David Palmer (LANL) on behalf of the Swift Team on 24 Aug 2008; 5:13 UT SGR 0501+4516 (ATEL #1676, Barthelmy et al.; and other recent ATELs and GCNs) continues to be active, with 32 bursts detected and identified by Swift-BAT in the 36 hours following the first detected burst at 2008-08-22 12:41:59 UT. (A comparable number of bursts presumably occurred during the intervals when the SGR was behind the Earth as seen from Swift.) For most of these bursts, Swift was directly observing the source with XRT and UVOT. The SGR is Moon-constrained for XRT and UVOT currently (from ~2008-08-24 02:00 to ~2008-08-26 05:00 UT), however Swift will be pointed to keep the SGR in the BAT field-of-view when possible. A list of burst times follows. Times are from the BAT onboard trigger, which usually corresponds to an instant somewhere between the onset and the peak of the event, and are not barycentered. Trigger duration is a reasonable proxy for burst duration in most cases. Except for the bursts detected during slews, all have been verified by BAT imaging to have come from the SGR. The brighter bursts, with BAT instrumental fluences above 2000 counts, are marked with asterisks. The very brightest bursts have fluxes in the kiloCrab range. SGR 0501+4516 burst times BAT Trigger time UT Trig dur (ms) Notes 2008-08-22T12:41:59.457 64 * 2008-08-22T13:09:04.353 256 2008-08-22T13:12:52.697 16 * 2008-08-22T13:20:30 slew 2008-08-22T14:17:55.361 256 2008-08-22T14:34:26.493 32 2008-08-22T17:29:30.017 64 2008-08-22T22:24:24.008 32 2008-08-22T22:36:53.368 32 2008-08-22T22:53:50.760 16 2008-08-23T00:28:12.536 32 2008-08-23T02:11:39 * slew 13kcounts 2008-08-23T04:47:48.599 16 * 35kcounts 2008-08-23T06:31:36.571 16 2008-08-23T06:58:15 slew 2008-08-23T08:30:04.191 16 * 2008-08-23T08:34:56.719 32 2008-08-23T11:07:37.827 16 2008-08-23T11:27:35.107 16 * 90kcounts 2008-08-23T14:27:37.018 64 2008-08-23T14:56:26.238 64 * 2008-08-23T16:31:22.326 16 2008-08-23T17:35:14.362 32 * 17kcounts 2008-08-23T17:35:14.910 128 2008-08-23T17:59:01.430 8 2008-08-23T19:08:09.886 128 2008-08-23T20:49:10.238 256 2008-08-23T20:53:29.110 16 2008-08-23T21:09:19.518 32 2008-08-23T21:11:17.210 64 2008-08-23T21:11:19.630 16 2008-08-23T21:13:39.838 64 2008-08-23T22:37:55.349 08 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8127 SUBJECT: SGR 0501+4516: Astrotel-Caucasus optical observations DATE: 08/08/24 18:45:32 GMT FROM: Denis Denissenko at IKI, Moscow T. V. Kryachko (Astrotel Observatory, KSU/AST), D. V. Denisenko (IKI) and B. L. Satovskiy (Astrotel) report: We have observed the field of SGR 0501+4516 (Barthelmy et al., GCN 8113; ATel 1676) remotely with 30-cm Astrotel-Caucasus telescope from Aug. 23, 21:08:46 UT to Aug. 24, 01:21:52 UT. In total, forty-five 300-sec exposures were obtained. The first image taken at large zenith distance (69 deg) and with the last-quarter Moon only 26 deg away serendipitously covered an interval of burst activity from SGR 0501+4516. Four BAT triggers occurred during these five minutes (Palmer, ATel 1678). No object was found in our image inside the XRT error box or at the position of possible UKIRT nIR counterpart (Tanvir and Varricatt, GCN 8126) to the limiting magnitude of R=19.0. Comparison with the next image did not show any significant brightening of the variable star mentioned in GCN 8114. The analysis of full data set is underway. Future observations of the field with Astrotel-Caucasus are planned. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8129 SUBJECT: SGR 0501+4516: MDM Optical Observations DATE: 08/08/24 23:55:33 GMT FROM: Jules Halpern at Columbia U. I observed the Swift XRT location of SGR 0501+4516 (Holland et al., GCN #8112; Barthelmy et al., GCN #8113) in the R-band using the MDM 2.4m telescope on the nights of Aug. 23 and 24 UT. Preliminary flux calibration was performed with Landolt standard stars. In a sequence of 90 s exposures from Aug. 24 09:55 UT to 11:49 UT, I find variability of the star noted by Denisenko (GCN #8114) as variable between POSS epochs. It began at R = 17.16, remaining at plateau for the first hour, then declined monotonically to R = 17.35 over the next hour. Within a radius of 10" of the XRT position, there is no new object that is not on the POSS to a limit of R = 23.0 in the summed images from Aug. 24. I also obtained a series of 10 s exposures that bracketed the time of the large flare on Aug. 23 11:27:35 UT (Gehrels et al., GCN #8124), but unfortunately did not include it. No optical increase is seen in the Denisenko star in an exposure beginning 16 s after the burst to a limit of 0.05 magnitudes. No new object appears in the vicinity of the XRT position to a limit of R = 20.5 in this image. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8130 SUBJECT: Radio Detection of SGR 0501+4516 DATE: 08/08/25 14:25:40 GMT FROM: Shri Kulkarni at Caltech S. R. Kulkarni and D. A. Frail report: We undertook VLA observations of SGR 0501+4516 (GCN 8113) on 2008 August 24 (starting at 0928 UT, 30 min duration) and 2008 August 25 (starting at 1054 UT, 1 hour duration) in the 8-GHz and 1.4 GHz bands. No source was detected in the first epoch in the 8-GHz band (75 microJy rms), consistent with the lack of detection by WSRT (GCN 8125) on 2008 August 23 (03.66 to 09.49 UT). A very strong source is seen in the second epoch: 3 +/- 0.1 mJy (8.46 GHz) 14 +/- 0.8 mJy (1.43 GHz) The spectral index is -1 between these two frequencies. One may conclude that SGR 0501+4516 is waking up from hibernation. Radio observations at other frequencies are strongly encouraged (to constrain the spectrum). Searches for radio pulsations can be expected to be highly productive. Finally, should the source remain radio bright, proper motion measurements via VLBI become feasible. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8131 SUBJECT: INTEGRAL ToO Observation of SGR0501+4516 DATE: 08/08/25 16:22:21 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley and D. Gotz, on behalf of the INTEGRAL AO-6 SGR ToO team, report: We have triggered an approved INTEGRAL ToO observation of SGR0501+4516. The planned observing times during revolution 717 will be: Start time Duration (s) 2008-08-27 00:46:16.0 105624 2008-08-28 07:47:52.0 32274 2008-08-28 17:39:00.0 44010 2008-08-29 06:50:02.0 23472 SPI will not be operating during these observations, due to annealing. We encourage simultaneous observations at all wavelengths. Any last-minute schedule changes will be posted at http://integral.esac.esa.int/isocweb/schedule.html?action=intro //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8132 SUBJECT: Konus-Wind observations of new SGR 0501+4516 DATE: 08/08/25 18:15:54 GMT FROM: Dmitry Frederiks at Ioffe Institute S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, P. Oleynik, D. Svinkin, M. Ulanov and T. Cline, on behalf of the Konus-Wind team report: On August 23-25 Konus-Wind detected in triggered mode four bursts from new SGR 0501+4516 (Holland et al. GCN 8112, Barthelmy et al. GCN 8113). First two of these bursts were localized by Swift (Palmer et al. ATel #1678). The others had the same estimated ecliptic latitude, temporal structure and spectral parameters and so we can with great degree of probability attribute them to the new SGR. The burst lightcurves vary from a single pulse with a duration of less than 50 ms to more complex structure lasting for ~500ms. The spectra of the bursts demonstrate a pronounced spectral evolution and are well fitted (in the 20-200 keV range) by the power law with exponential cutoff. The bursts energetics in this range is summarized in the table below. The high values of the peak fluxes, comparable to ones for the strongest recurrent bursts from the other known SGRs may imply the lower distance to the source. -------------------------------------------------------------------- Date UT Fluence Peak flux (2ms) erg/cm2 erg/cm2/s -------------------------------------------------------------------- 080823a 04:47:46.194(*) -- -- 080823b 11:27:32.652 4x10-6 7x10-5 080824 01:17:55.316 2.5x10-5 2x10-4 080825 04:48:27.445 3.3x10-6 1.6x10-4 -------------------------------------------------------------------- (*) data are incomplete at this time The Konus-Wind light curves are available at Ioffe website: http://www.ioffe.ru/LEA/SGRs/080823_T41252/ http://www.ioffe.ru/LEA/SGRs/080824_T04675/ http://www.ioffe.ru/LEA/SGRs/080825_T17307/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8134 SUBJECT: SGR 0501+4516: radio pulsar searches with GBT and WSRT DATE: 08/08/25 22:35:47 GMT FROM: Nanda Rea at U of Amsterdam J. Hessels (Univ. of Amsterdam), N. Rea (Univ. of Amsterdam), S. Ransom (NRAO), B. Stappers (Univ. of Manchester), & collaborators On 2008 August 23 14:53 (UT) we observed the recently discovered Soft Gamma-Ray Repeater SGR J0501+4516 (GCN 8112, 8113) with the Green Bank Telescope (GBT) for about 1 hour, using the Pulsar Spigot at 2 GHz. Folding the data at the X-ray rotational period of 5.769s (ATEL 1677) revealed no radio pulsations over a wide range of trial dispersion measures (DMs). We place an upper limit of 40microJy on a putative radio pulsar at this epoch, consistent with synthesis upper limits on the radio counterpart from earlier that day (GCN 8125). We have also searched a large range of DMs for individual bright pulses and bursts. No obvious radio bursts were found down to a time resolution of 3ms and a maximum DM of 1000 pc/cm^3. Note that during our observation Swift-BAT observed a large burst (on 2008 August 23 14:56:26 UT; ATEL 1678) for which no obvious radio counterpart was detected. We are continuing to analyze these data to search for fainter signals. Westerbork observations are planned starting on 2008 August 26 03:00 (UT) to search for pulsations from the recently reported VLA radio counterpart (GCN 8130). A GBT ToO monitoring program to search for radio pulsations has been requested. We would like to thank the GBT schedulers for their prompt attention to our request for observations. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8136 SUBJECT: Suzaku ToO Observation of SGR 0501+4516 DATE: 08/08/26 02:19:05 GMT FROM: Yujin E. Nakagawa at RIKEN Kazuhisa Mitsuda on behalf of Suzaku team report: A Suzaku ToO observation of the newly discovered SGR 0501+4516 (Barthelmy et al. 2008, GCN Circular, 8113) has started at 00:05:00 on August 26 2008 (UT). It will continue until 08:25:00 on 27 August 2008 (UT). All the Suzaku narrow field instruments (XIS and HXD: 0.2-600 keV energy range) are on during the observation. Further follow-up observations at other wavelengths are encouraged. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8138 SUBJECT: Soft Gamma Repeater SGR 0501+4516: GBM Detection of multiple bursts DATE: 08/08/26 15:50:37 GMT FROM: Chryssa Kouveliotou at MSFC Soft Gamma Repeater SGR 0501+4516: GBM Detection of multiple bursts C. Kouveliotou (NASA/MSFC), P.N. Bhat (UAH), E. Bissaldi (MPE), M.S. Briggs (UAH), V. Connaughton (UAH), R. Diehl (MPE), G.J. Fishman (NASA/MSFC), L. Gibby (NASA/MSFC), J. Greiner (MPE), A.S. Hoover (LANL), A.J. van der Horst (NASA/ORAU), R.M. Kippen (LANL), G.G. Lichti (MPE), C.A. Meegan (NASA/MSFC), S. McBreen (MPE), W.S. Paciesas (UAH), R.D. Preece (UAH), H. Steinle (MPE), A. von Kienlin (MPE), M.S. Wallace (LANL), and C.A. Wilson-Hodge (NASA/MSFC)report: The GLAST Burst Monitor has thus far triggered on 23 bursts from SGR 0501+5416, newly discovered with Swift (Holland et al. 2008, GCN Circ. 8112, Barthelmy et al. 2008, GCN 8113 and GCN 8119). Additional un-triggered bursts have been detected in the data; a complete census is underway. The first GBM trigger was on 2008, August 22 (von Kienlin et al. 2008, GCN 8122). The GBM team will issue future individual GCN Circulars only for exceptionally bright SGR events. The GBM triggered-event rate has peaked at 14 events on 2008 August 23 and seems to be slowing down with only 2 on 2008, August 26. We have so far identified five events in common with Swift and three with Konus-Wind. The event intensities range from weak to very bright; their durations range between ~50 - 500 msec. Event spectra are on the average best fit with a power law with an exponential cutoff and peak energies ~ 40-50 keV. Taking into account the source location at the Galactic anti-center, we assume a distance between 2-5 kpc, which corresponds to a range of burst luminosities ~10^37 - 10^40 ergs. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8139 SUBJECT: SGR 0501+4516: Fermi GBM (formerly GLAST Burst Monitor) observations of three exceptionally intense outbursts DATE: 08/08/26 22:10:21 GMT FROM: Jerry Fishman at NASA-MSFC G. J. Fishman (MSFC), S. McBreen (MPE), M. S. Briggs (UAH), C. Kouveliotou (MSFC), A. von Kienlin (MPE), A. J. van der Horst (MSFC/ORAU), P. N. Bhat (UAH), C. A. Meegan (MSFC), report for the Fermi GBM team: A recent GCN Circ. (Kouveliotou, et al., GCN 8138) summarizes observations of SGR 0501+4516,as seen with the Fermi GBM (formerly GLAST Burst Monitor). Below, we report on three exceptionally large events from this data set observed on 24 and 25 August 2008. Peak fluxes are over a time interval of 64 ms and fluences for the durations listed; both are for the energy range 20 to 200 keV. All event spectra were best fit with a power law and an exponential cutoff; their spectral parameters are also given below. These large events may have observable ionospheric disturbances associated with them. ---------------------------------------------------------------------- Date UT Fluence Peak flux Index E(peak) Duration (erg/cm2) (erg/cm2-s) (keV) (ms) 080824* 1:17:57 2.2E-5 1.6E-4 0.21 50 448 080825* 4:48:29 2.7E-6 3.6E-5 0.14 39 192 080825 9:37:44 9.9E-7 1.0E-5 0.32 38 320 * - reported by S. Golenetskii from Konus-Wind data (GCN 8132) ----------------------------------------------------------------------- //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8146 SUBJECT: SGR 0501+4516: Swift XRT measure of the spin period DATE: 08/08/27 17:53:30 GMT FROM: Vanessa Mangano at INAF-IASFPA V. Mangano (INAF-IASF PA), J. Kennea (PSU), M. Perri (ASDC), G. Cusumano (INAF-IASF PA), D. N. Burrows (PSU), N. Gehrels (GSFC), D. Palmer (LANL), S. Barthelmy (GSFC) report on behalf of the Swift Team: Swift XRT observed SGR 0501+4516 from 2008-08-22 12:43:36 s UT to 2008-08-24 01:35:43 s UT in Photon Counting (PC) mode and from 2008-08-26 05:14:58 s UT to 2008-08-27 02:31:59 s UT in Windowed Timing (WT) mode for a total of about 38 ks exposure in PC and 30 ks in WT. We performed the barycentric correction of photon arrival times and a search for coherent pulsations over the full data set in the 0.2-10 keV band with epoch folding search techniques. We had a highly significant detection at the period P = 5.7620697 +/- 0.0000015 s The quoted error is at the 90% confidence level and have been calculated following the method described in Cusumano, Massaro & Mineo, 2003, A&A, 402, 647. The reference epoch is at 2008-08-22 12:42:08.278 s (Terrestrial time) corresponding to the beginning of the PC observation. This value is at < 2 sigma from the RXTE measure of 5.769 ± 0.004 s (Gogus et al. 2008, ATEL #1677). The folded light curve shows a perfectly sinusoidal profile with a pulsed fraction of 17% (calculated as the half the difference between the maximum and minimum count rates). Further analysis to look for possible period evolution is ongoing. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8147 SUBJECT: SGR 0501+4516: GMRT Radio Observation at 618 MHz DATE: 08/08/27 18:15:09 GMT FROM: Sayan Chakraborti at TIFR,Mumbai,India We observed the field of the newly discovered SGR 0501+4516 (GCN 8112, 8113) with the Giant Metrewave Radio Telescope at a central frequency of 618 MHz between 03 to 08 UT on 25 August 2008. We do not detect a radio source at the position of the SGR. The rms noise reached in the map is around 0.11 mJy per beam. We place an upper limit to the flux at the target position of around 0.7 mJy at the 3 sigma level, due to nearby bright sources. We thank the staff of GMRT who made this observation possible. GMRT is run by the National Centre for Radio Astrophysics (NCRA) of the Tata Institute of Fundamental Research (TIFR). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8148 SUBJECT: Enhanced Swift-XRT position of SGR 0501+4516 DATE: 08/08/27 19:10:32 GMT FROM: Phil Evans at U of Leicester P.A. Evans and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team: Using 9.1 ks of XRT Photon Counting mode data and 35 UVOT images, we find an astrometrically corrected X-ray position for SGR 0501+4516 (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 75.27834, +45.27649 which is equivalent to: RA (J2000): 05h 01m 6.80s Dec (J2000): +45d 16' 35.4" with an uncertainty of 1.4 arcsec (radius, 90% confidence). This position is consistent with the possible infra-red counterpart (Tanvir & Varricatt, GCN Circ. 8126). The position enhancement process is described by Goad et al. (2007, A&A, 476, 1401 http://www.swift.ac.uk/xrt_positions/Goad.pdf), the current algorithm is an extension of this method. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8149 SUBJECT: SGR 0501+4516: Proximity to supernova remnant HB9 DATE: 08/08/27 21:04:34 GMT FROM: Bryan Gaensler at U of Sydney B. M. Gaensler (U. Sydney) and S. Chatterjee (U. Sydney) report: We note that the newly identified magnetar SGR 0501+4516 (GCN 8113) is in close proximity to the Galactic supernova remnant (SNR) HB9 = G160.9+2.6. Specifically, the location of the SGR as determined by Swift XRT (GCN 8112; GCN 8148) is just outside the south-eastern rim of HB9. A 1.4 GHz radio image of the SNR taken from the Canadian Galactic Plane Survey, and showing the position of the SGR, is available at: http://www.physics.usyd.edu.au/~bmg/fig_sgr_snr.gif The angular separation from the SNR's centre is approximately 80 arcmin, corresponding to a projected space velocity of 1700-4300 km/s for a distance to the SNR of 1.5 kpc and an age of 8000-20000 years (Leahy & Aschenbach, 1995, A&A, 293, 853). The SGR's location outside the rim of a SNR and its high inferred space velocity are similar properties to those inferred for other SGRs. While there is as yet insufficient information to judge the validity of a physical association between SGR 0501+4516 and SNR HB9, we note that this anti-centre region is relatively devoid of SNRs and other evidence for massive star formation: there are only two other catalogued SNRs within 15 degrees of this position. A search for other neutron stars associated with HB9 (Kaplan et al., 2006, ApJS, 163, 344) did not detect any candidates. //////////////////////////////////////////////////////////////////////// ATEL #1682 ATEL #1682 Title: Swift XRT measure of the SGR 0501+4516 spin period Author: V. Mangano (INAF-IASF PA), J. Kennea (PSU), M. Perri (ASDC), G. Cusumano (INAF-IASF PA), D. N. Burrows (PSU), N. Gehrels (GSFC), D. Palmer (LANL), S. Barthelmy (GSFC) Queries: vanessa@ifc.inaf.it Posted: 27 Aug 2008; 17:49 UT Subjects: X-ray, Pulsars, Soft Gamma-ray Repeaters, Transients Swift XRT observed SGR 0501+4516 from 2008-08-22 12:43:36 s UT to 2008-08-24 01:35:43 s UT in Photon Counting (PC) mode and from 2008-08-26 05:14:58 s UT to 2008-08-27 02:31:59 s UT in Windowed Timing (WT) mode for a total of about 38 ks exposure in PC and 30 ks in WT. We performed the barycentric correction of photon arrival times and a search for coherent pulsations over the full data set in the 0.2-10 keV band with epoch folding search techniques. We had a highly significant detection at the period P = 5.7620697 +/- 0.0000015 s The quoted error is at the 90% confidence level and have been calculated following the method described in Cusumano, Massaro & Mineo, 2003, A&A, 402, 647. The reference epoch is at 2008-08-22 12:42:08.278 s (Terrestrial time) corresponding to the beginning of the PC observation. This value is at < 2 sigma from the RXTE measure of 5.769 ? 0.004 s (Gogus et al. 2008, ATEL #1677). The folded light curve shows a perfectly sinusoidal profile with a pulsed fraction of 17% (calculated as the half the difference between the maximum and minimum count rates). Further analysis to look for possible period evolution is ongoing. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8150 SUBJECT: SGR 0501+4516: Decline in Activity DATE: 08/08/28 01:10:37 GMT FROM: David Palmer at LANL This is a duplicate of ATEL #1683 (which should be cited instead of this GCN) copied to GCN as a courtesy to the gamma-ray burst community. David Palmer (LANL) on behalf of the Swift Team, reports: SGR 0501+4516 (ATEL #1675, #1676, #1677, #1678, #1682) has declined in activity. There have been no reported bursts in 43 hours, compared to the previous period with 56 bursts in 87 hours and a largest gap of 8 hours. Due to the unpredictable nature of these objects, this does not necessarily imply that it has returned to a multi-year (or even multi- day) quiescent stage. As of the latest available Swift-BAT data, 2008-08-27 22:40 UT, the most recent reported burst from the SGR was detected by Konus-Wind on 2008-08-26 at 03:16:15 (Konus-Wind team, private communication). The most recent BAT detection was about 8 hours earlier. The current list of BAT bursts, plus the reported Konus Wind bursts (from GCN #8132), follows. As in ATEL #1676, which this expands, the bursts with more than 2000 counts in the BAT are marked with a '*'. Trigger time (UTC) Trigger (ms) Notes 2008-08-22 12:41:59 64 * 2008-08-22 13:09:04 256 2008-08-22 13:12:53 16 * 2008-08-22 13:20:30 during slew 2008-08-22 14:17:55 256 2008-08-22 14:34:26 32 2008-08-22 17:29:30 64 2008-08-22 22:24:20 32 2008-08-22 22:36:53 32 2008-08-22 22:53:51 16 2008-08-23 00:28:13 32 2008-08-23 02:11:39 * during slew, 13k BAT counts 2008-08-23 04:47:49 16 * 35k BAT counts, seen by Konus-Wind 2008-08-23 06:31:37 16 2008-08-23 07:01:12 during slew, wrong time in ATEL #1678 2008-08-23 08:30:04 16 * 2008-08-23 08:34:57 32 2008-08-23 11:07:38 16 2008-08-23 11:27:35 16 * 90k BAT counts, seen by Konus-Wind 2008-08-23 14:27:37 64 2008-08-23 14:56:26 64 * 2008-08-23 16:31:22 16 2008-08-23 17:35:14 32 * 17k BAT counts 2008-08-23 17:35:15 128 2008-08-23 17:59:01 8 2008-08-23 19:08:10 128 2008-08-23 20:49:10 256 2008-08-23 20:53:29 16 2008-08-23 21:09:20 32 2008-08-23 21:11:17 64 2008-08-23 21:11:20 16 2008-08-23 21:13:40 64 2008-08-23 22:37:55 8 2008-08-24 00:05:30 128 2008-08-24 00:19:47 8 * 2008-08-24 01:17:55 Seen by Konus-Wind, not by BAT 2008-08-24 01:53:07 32 2008-08-24 02:02:47 32 2008-08-24 02:04:36 32 2008-08-24 06:56:53 32 2008-08-24 08:18:27 32 2008-08-24 08:23:39 16 * double peak 2008-08-24 08:23:39 32 2008-08-24 10:17:37 128 2008-08-24 18:19:38 128 2008-08-24 19:52:53 64 * 2008-08-24 22:30:12 16 2008-08-25 00:46:28 32 2008-08-25 03:19:18 32 2008-08-25 04:48:27 Seen by Konus-Wind, not by BAT 2008-08-25 10:22:03 16 2008-08-25 11:55:32 32 2008-08-25 19:24:09 32 2008-08-26 03:16:15 Seen by Konus-Wind, not by BAT This GCN may not be cited. Please cite ATEL #1683 instead. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8152 SUBJECT: SGR 0501+4516: XMM-Newton monitoring schedule DATE: 08/08/28 08:09:36 GMT FROM: Nanda Rea at U of Amsterdam N. Rea (U. Amsterdam), G.L. Israel, S. Mereghetti, A. Tiengo, P. Esposito (INAF), D. Gotz (CEA-Saclay) on behalf of a larger collaboration We have triggered a ToO monitoring observation of SGR 0501+4516 with XMM-Newton. The planned observing windows are: Start(UT) Duration [s] 2008-08-29 06:48 26000 2008-08-31 09:45 22000 2008-09-02 09:45 22000 2008-09-06 13:20 27500 Simultaneous observations at all wavelengths are encouraged. We are grateful to the XMM-Newton planning team for the efficiency in scheduling these observations, and to Norbert Schartel for approving our trigger. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8154 SUBJECT: Radio Detection of SGR 0501+4516: Retraction DATE: 08/08/28 14:02:44 GMT FROM: Dale A. Frail at NRAO D. A. Frail and S. R. Kulkarni report: We have re-analyzed the VLA data taken at the VLA on 2008 August 24 and 25. We were unable to confirm the detection reported early by Kulkarni & Frail (GCN 8130). The radio source seen in the second epoch appears to be spurious, an artifact of the observing method, missed in the initial data reduction. Combining all data from August 24 and 25, the final limits on the flux density at the position of the SGR are: 43 +/- 400 uJy (1.43 GHz) -12 +/- 23 uJy (8.46 GHz) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8155 SUBJECT: VLA non-detection of SGR 0501+4516 DATE: 08/08/28 15:24:33 GMT FROM: Joseph Gelfand at NYU/NSF Joseph D. Gelfand (NYU / NSF), Gregory Taylor (UNM), Chryssa Kouveliotou (NASA/MSFC), Bryan Gaensler (U. Sydney), and Alexander J. van der Horst (NASA/ORAU) report: A VLA observation of SGR 0501+4516 (GCN 8113) on 2008 August 27 between 0846 UT and 1215 UT did not detect a radio source at the position reported in GCN 8148 at any of the four observed frequencies. The five sigma upper-limits on the radio emission during this period are: 1.4 GHz < 1 mJy (rms = 0.2 mJy) 4.8 GHz <0.15 mJy (rms = 30 uJy) 8.5 GHz < 0.2 mJy (rms = 40 uJy) 22 GHz < 1.5 mJy (rms = 0.3 mJy) We would like to thank NRAO for promptly scheduling these VLA observations. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8159 SUBJECT: SGR 0501+4516: WHT observations of the possible near-infrared counterpart DATE: 08/08/29 10:34:57 GMT FROM: Nanda Rea at U of Amsterdam N. Rea (U. Amsterdam), E. Rol (U. Leicester), P.A. Curran (U. Amsterdam), I. Skillen (Isaac Newton Group), D.M. Russell (U. Amsterdam), G.L. Israel (INAF) on behalf of a larger collaboration On 2008 August 25 we observed the new Soft Gamma-ray Repeater SGR 0501+4516 with LIRIS, the near-infrared imager on the William Herschel Telescope (WHT) in La Palma. The observations were performed in the Ks band with a total exposure time of 1.8 hours. We clearly detect one object within the refined XRT error circle (GCN 8148), at the position: 05:01:06.74 +45:16:34.1 (J2000) with an uncertainty of 0.25 arcseconds (with respect to 2MASS astrometry). This is consistent with being the UKIRT suggested nIR counterpart (GCN 8126). We find the object at a magnitude of 19.2+/-0.2 (with respect to 2MASS calibration), slightly fainter than the UKIRT detection. We plan to take further observations from WHT in a few days to confirm this very tentative nIR variability. We wish to thank Chris Benn and Rene Rutten for promptly approving our Target of Opportunity request. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8160 SUBJECT: SGR 0501+4516: Detection of possible optical counterpart DATE: 08/08/29 11:49:38 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia T. Fatkhullin (SAO-RAS Nizhnij Arkhyz), A. de Ugarte Postigo (ESO Santiago), A. J. Castro-Tirado, J. Gorosabel and M. Jelínek (IAA-CSIC Granada), V. Sokolov (SAO-RAS), S. Guziy (Nikolaev State Univ.), A. Pozanenko (IKI-RAS Moscow), E. Sonbas (Cukurova Univ.) and D. Pérez-Ramírez (U. Leicester), on behalf of a larger collaboration, report: "Continuing with our monitoring campaign of the field of the SGR 0501+4516 (Holland et al. GCNC 8112, Barthelmy et al. GCNC 8113) we have used the 6.0m BTA telescope (equipped with SCORPIO) at the Special Astrophysical Observatory (SAO, Russia). A combination of exposures adding a total of 1530s in the I-band obtained at a mean epoch of August 25.18468 UT shows a low S/N source consistent with the NIR object reported by Tanvir and Varrycatt (GCN 8126), with a magnitude of I = 23.3 ± 0.4. Taking into account the nIR magnitude reported by Rea et al. at about the same epoch (GCNC 8159), we derive an apparent color index (I-Ks) = 4.1 ± 0.6, uncorrected for Galactic extinction in the line of sight to the source. Further observations are planned." This message can be quoted. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8162 SUBJECT: SGR 0501+4516: Confirmation of the NIR counterpart DATE: 08/08/29 22:06:04 GMT FROM: Antonio Deugarte at IAA-CSIC A. de Ugarte Postigo (ESO, Santiago), A. J. Castro-Tirado, J. Gorosabel (IAA-CSIC, Granada), M. Morales-Calderón and N. Huélamo (LAEFF-INTA, Madrid), on behalf of a larger collaboration, report: We have observed the field of SGR 0501+4516 (Holland et al. GCNC 8112, Barthelmy et al. GCNC 8113) using the 4.2m WHT (equipped with LIRIS) on Aug. 29.245 UT. A short integration in the K-band does not show any source at the position of the proposed NIR counterpart (Tanvir et al. GCNC 8126) down to a 3-sigma limiting magnitude of K~19.5. This is consistent with the flux decline observed by Rea et al. on Aug 25 (GCNC 8159) and would correspond with the decline in high energy activity reported by Palmer (GCN 8150, ATEL #1683). This implies that the source reported in the NIR by Tanvir et al. and in the optical by Fatkhullin et al. (GCNC 8160) is most likely the counterpart for SGR 0501+4516 at these wavelengths. This message can be quoted. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8163 SUBJECT: INTEGRAL ToO observation of SGR0501+4516 DATE: 08/09/01 18:54:53 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley and D. Gotz, on behalf of the INTEGRAL AO-6 SGR collaboration, report: INTEGRAL carried out a ToO observation of SGR 0501+4516 from 2008-08-27T00:46 to 2008-08-29T13:36 (GCN 8131). A very preliminary analysis of the data indicates that IBIS/ISGRI detected the quiescent X-ray emission at the 2 mCrab level between 20 and 40 keV. At least four bursts were detected, at 2008-08-27T16:25:14 2008-08-27T22:25:57 2008-08-28T03:32:28 2008-08-28T20:59:42 Data analysis is ongoing. We would like to thank the INTEGRAL project for their support and particularly Dominique Eckert and Volker Beckmann for the quick-look analysis. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8164 SUBJECT: nIR observations of SGR 0501+4516 DATE: 08/09/02 12:27:14 GMT FROM: Evert Rol at U.Leicester E. Rol, N. Tanvir (U. of Leicester), N. Rea (U. of Amsterdam), K. Wiersema (U. of Leicester), I. Skillen (ING) and P. A. Curran (U. of Amsterdam) report for a larger collaboration: We observed the candidate counterpart to SGR 0501+4516 with LIRIS at WHT, Roque the Los Muchachos and NIRI at Gemini-North, Mauna Kea, around August 31, 3 UT and September 1, 14 UT, respectively. On both epochs, we measure a magnitude of K = 19.1 +/- 0.1, consistent with the magnitude previously reported in GCN 8159 (magnitudes calibrated to 2MASS). This is in contrast to the upper limit given in GCN 8162, though our observations do not preclude a sudden decrease and subsequent rise to the previous flux level. Our observations, however, indicate a relatively stable nIR counterpart candidate over this time interval. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8165 SUBJECT: SGR 0501+4516: preliminary results of the first XMM-Newton observation DATE: 08/09/02 13:51:00 GMT FROM: Nanda Rea at U of Amsterdam N. Rea (U. Amsterdam), S. Mereghetti (INAF-IASF, Milan), G.L Israel (INAF-OAR), P. Esposito, A. Tiengo (INAF-IASF, Milan), S. Zane (UCL-MSSL) report on behalf of a larger collaboration: XMM-Newton observed the new Soft Gamma-ray Repeater SGR 0501+4516 (Holland et al., GCN 8112; Barthelmy et al., GCN 8113) for ~49ks on 2008 August 23rd starting at 01:04:00 (UT). Preliminary results show that the source flux is enhanced in the soft X-ray range with respect to the possible quiescent ROSAT counterpart (Kennea et al., Atel 1675). The source persistent EPIC-PN spectrum is well fitted (in the 1-10keV energy range; reduced chi2 = 1.02) by an absorbed blackbody plus a power-law with Nh = 0.89(2) x 1022 cm-2, kT = 0.69(5) keV and photon index Gamma= 2.76(6). The absorbed 1-10keV flux is 3.96x10-11 erg/s/cm2. We measure a spin period of 5.762069(5)s (consistent with the RXTE and Swift-XRT determinations: Gogus et al., Atel 1677; Mangano et al., Atel 1682), with a fundamental component pulsed fraction of 40(1)% (pulsed fraction defined as the background-corrected semi-amplitude of the best fitting sine component, and in the whole EPIC-PN energy band). Several short X-ray bursts have been detected in this observation, the brightest ones also observed by Swift BAT (Palmer et al., Atel 1678). A detailed analysis of this and the subsequent observations of our XMM-Newton monitoring program (Rea et al., GCN 8152) is in progress. Note that we postponed the last observation of our monitoring (September 6th, see GCN 8152), and will promptly diffuse a new date encouraging multiwavelegth follow-ups. We thank Norbert Schartel and the XMM-Newton team for carrying out this ToO observation. [GCN OPS NOTE(10sep08): Per author's request, in the Subject-line, the "0105" was changed to "0501".] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8166 SUBJECT: SGR 0501+4516: Spin Down Rate and Inferred Dipole Magnetic Field DATE: 08/09/02 16:00:32 GMT FROM: Chryssa Kouveliotou at MSFC SGR 0501+4516: Spin Down Rate and Inferred Dipole Magnetic Field Peter M. Woods (Dynetics), Ersin Gogus (Sabanci University), Chryssa Kouveliotou (NASA/MSFC), report on behalf of a larger collaboration: We continued monitoring the new Soft Gamma Repeater SGR 0501+4516 (Barthelmy et al. 2008, GCN # 8113, Palmer et al. 2008, ATel # 1678) using our SGR ToO Program with RXTE. We acquired a total exposure of 40 ks in 13 RXTE pointings performed over a time span of ~7.5 days. The time spacing between each pointing ranged between 0.1 - 0.9 d. We detect numerous (between 1 to 50) short bursts in observations before 2008 August 28. We clearly detect the 5.76 s pulsations reported by Gogus et al. 2008 (ATel # 1677) in the 2-10 keV PCA data. We employed a quadratic spline fit to phase residuals and measured the spin period, P = 5.762067(2) s and the spin-down rate, Pdot = 1.5(5) x 10^-11 s/s. Note that our spin period measurement is consistent with that reported by Mangano et al. (2008, ATel # 1682). Assuming that the neutron star slows down via magnetic dipole radiation, we infer a dipole magnetic field of B = 3 x 10^14 G, confirming the new SGR as a new magnetar candidate. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8168 SUBJECT: Recent VLA non-detection of SGR 0501+4516 DATE: 08/09/02 18:17:02 GMT FROM: Joseph Gelfand at NYU/NSF Joseph D. Gelfand (NYU / NSF), Gregory Taylor (UNM), Chryssa Kouveliotou (NASA/MSFC), Bryan Gaensler (U. Sydney), and Alexander J. van der Horst (NASA/ORAU) report: A VLA observation of SGR 0501+4516 (GCN 8113) on 2008 August 31 between 1109 UT and 1358 UT did not detect a radio source at the position reported in GCN 8148 at 4.8 GHz, the only frequency used during this observation. The resultant five sigma upper-limit on the radio emission during this period is < 0.1 mJy (rms = 20 uJy). We would like to thank NRAO for promptly scheduling these VLA observations. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8212 SUBJECT: SGR J0501+4516: radio pulsar searches with GBT and WSRT DATE: 08/09/10 21:55:36 GMT FROM: Scott Barthelmy at NASA/GSFC J. Hessels (Univ. of Amsterdam), N. Rea (Univ. of Amsterdam), S. Ransom (NRAO), B. Stappers (Univ. of Manchester), & collaborators On 2008 August 23 14:53 (UT) we observed the recently discovered Soft Gamma-Ray Repeater SGR J0501+4516 (GCN 8112, 8113) with the Green Bank Telescope (GBT) for about 1 hour, using the Pulsar Spigot at 2 GHz. Folding the data at the X-ray rotational period of 5.769s (ATEL 1677) revealed no radio pulsations over a wide range of trial dispersion measures (DMs). We place an upper limit of 40microJy on a putative radio pulsar at this epoch, consistent with synthesis upper limits on the radio counterpart from earlier that day (GCN 8125). We have also searched a large range of DMs for individual bright pulses and bursts. No obvious radio bursts were found down to a time resolution of 3ms and a maximum DM of 1000 pc/cm^3. Note that during our observation Swift-BAT observed a large burst (on 2008 August 23 14:56:26 UT; ATEL 1678) for which no obvious radio counterpart was detected. We are continuing to analyze these data to search for fainter signals. Westerbork observations are planned starting on 2008 August 26 03:00 (UT) to search for pulsations from the recently reported VLA radio counterpart (GCN 8130). A GBT ToO monitoring program to search for radio pulsations has been requested. We would like to thank the GBT schedulers for their prompt attention to our request for observations. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8265 SUBJECT: SGR 0501+4516: preliminary results of the Suzaku ToO observation DATE: 08/09/18 04:41:04 GMT FROM: Kazutaka Yamaoka at Aoyama Gakuin U Y.E. Nakagawa (RIKEN), K. Yamaoka, A. Yoshida (AGU), T. Enoto, K. Nakazawa (U. Tokyo), K. Makishima (U. Tokyo/RIKEN), N. Rea (U. Amsterdam), P. Esposito (INAF/IASF), T. Sakamoto (GSFC/UMBC), and K. Hurley (U.C. Berkeley), on behalf of the Suzaku SGR ToO team, report: We report on a Suzaku ToO observation of the new soft gamma-ray repeater SGR 0501+4516 (Holland et al. GCN #8112, Barthelmy et al. GCN #8113), started on 2008-08-26 00:05 UT, for an exposure time of about 43 ksec (Mitsuda et al. GCN #8136). A bright point source was clearly detected in the XIS CCDs at a position consistent with that of SGR 0501+4516 (Evans et al. GCN #8148). From a preliminary analysis of the XIS data, the 1-10 keV persistent emission spectrum is well fit by a black body with a temperature of 0.7 keV, plus a power-law with a photon index of 2.9, absorbed by a hydrogen column density of 1.0x10^22 cm^-2. The absorbed 1-10 keV flux was (3.7+/-0.1)x10^-11 erg/cm^2/s. The XIS data confirm the source pulsations at a period of P = 5.762 +/- 0.001 s, consistent with the periodicity derived by the RXTE/PCA (Gogus et al. GCN #8118), Swift/XRT (Mangano et al. GCN #8146), and XMM-Newton (Rea et al. Atel #1688; Israel et al. Atel #1692) At least 16 short bursts were detected during the observation. The largest burst was observed on 2008-08-26 03:16:16 by all Suzaku's instruments including Suzaku-WAM, up to an energy of ~200 keV. The HXD spectral analysis of the persistent and burst emission is in progress. We would like to thank the Suzaku managers and the operation team for approving and carrying out the ToO observation. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8461 SUBJECT: SGR 0501+4516: optical observations in August DATE: 08/11/02 13:48:28 GMT FROM: Alexei Pozanenko at IKI, Moscow V. Rumyantsev, S. Artemenko (CrAO), A. Pozanenko (IKI), A. J. Castro-Tirado (IAA-CSIC Granada), report on behalf of larger GRB follow-up collaboration: We observed the field of SGR 0501+4516 (Holland et al. GCN 8112, Barthelmy et al. GCN 8113), in I band on August 26-28 with Shajn telescope of CrAO. The observation epochs are 2008-08-26T23:17:51 -- 2008-08-27T00:05:51 and 2008-08-27T23:27:32 -- 2008-08-28T00:31:32. We do not detect NIR/optical counterpart of SGR 0501+4516 (Tanvir et al, GCN 8126, Rea et al, GCN 8159, Fatkhullin et al, GCN 8160) in the first epoch, while in the second epoch (Aug. 27.9993) one may suggest a presence of counterpart. Upper limits of combined images are following: Mean epoch, Exposure, UL (3sigma) Aug. 26.9874 60x34 22.8 Aug. 27.9993 60x60 23.6