//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6542 SUBJECT: GRB 070616: Swift detection of a burst DATE: 07/06/16 17:02:59 GMT FROM: Scott Barthelmy at NASA/GSFC R. L. C. Starling (U Leicester), S. D. Barthelmy (GSFC), A. P. Beardmore (U Leicester), D. N. Burrows (PSU), P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), C. Guidorzi (Univ Bicocca&INAF-OAB), J. A. Kennea (PSU), C. B. Markwardt (CRESST/GSFC/UMD), F. E. Marshall (NASA/GSFC), P. T. O'Brien (U Leicester), J. P. Osborne (U Leicester), K. L. Page (U Leicester), D. M. Palmer (LANL), A. M. Parsons (GSFC), G. Sato (GSFC/ISAS), M. Stamatikos (NASA/ORAU), D. E. Vanden Berk (PSU) and L. Vetere (PSU) report on behalf of the Swift Team: At 16:29:33 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 070616 (trigger=282445). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 32.155, +56.948 which is RA(J2000) = 02h 08m 37s Dec(J2000) = +56d 56' 53" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows nothing much around T_zero (as is typical for image triggers). We note that there is bright and variable activity in the TDRSS lightcurve starting at T+100 sec and lasting to 600 sec. This may be long-term burst activity, although we can not rule out a contribution from a bright galactic source such as Cyg X-1 coming into the FOV (due to the slew). We will be able to separate this ambiguity when we get the full Malindi data to construct a mask-weighted lightcurve. The XRT began observing the field at 16:31:44 UT, 131 seconds after the BAT trigger. XRT found a bright, variable and fading, uncatalogued X-ray source. Using prompt downlinked data we find a position of located at RA, Dec 32.1513, +56.9451 which is RA(J2000) = 02h 08m 36.3s Dec(J2000) = 56d 56' 42.5" with an uncertainty of 4.9 arcseconds (radius, 90% containment). This location is 12.7 arcseconds from the BAT on-board position, within the BAT error circle. The initial flux in the 2.5s image was 7.6e-09 erg/cm2/s (0.2-10 keV). We note that this is 3.1 arcseconds from source USNO-B1.0 1469-0076513. UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm) filter starting 142 seconds after the BAT trigger. No afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 18.5 mag. The 8'x8' region for the list of sources generated on-board 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 large, but uncertain extinction expected. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6543 SUBJECT: GRB 070616, Swift-BAT partial refined analysis DATE: 07/06/16 20:11:00 GMT FROM: Scott Barthelmy at NASA/GSFC M. Stamatikos (GSFC/ORAU), L. Barbier (GSFC), S.D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS), R.L.C. Starling (U Leicester), J. Tueller (GSFC), T. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+497 sec from the recent telemetry downlink, we report further analysis of BAT GRB 070616 (trigger #282445) (Starling, et al., GCN Circ. 6542). The BAT ground-calculated position is RA, Dec = 32.096, 56.946 deg which is RA(J2000) = 02h 08m 23.0s Dec(J2000) = 56d 56' 45" with an uncertainty of 2.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 60%. The mask-weighted light curve shows many peaks. The burst started with a low-level smooth emission at ~T-55 sec continuing smoothly and increasing slowly until ~T+100 sec when the main emission started. The main peak is at T+120 sec. Smaller overlapping peaks continue out past T+500 sec (the limit of the downloaded data so far). We are currently in the gap of Malindi downlink passes, and will not receive more data until 03:30 UT 17 Jul 07. We will issue another Circular then describing the activity beyond T+500 sec and giving the T90 value. T90 is at least 175 sec. Since we do not have the full data set downlinked yet, we will not quote any spectral parameters at this time. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6545 SUBJECT: GRB 070616: TLS observation DATE: 07/06/17 01:39:22 GMT FROM: Alexander Kann at TLS Tautenburg D. A. Kann, U. Laux, B. Stecklum and S. Klose (TLS Tautenburg) report: We observed the field of Swift GRB 070616 (Starling et al., GCN 6542) with the Tautenburg 1.34m Schmidt telescope. A single 600 second image in Ic was obtained before clouds forced us to shut down. The airmass was 1.95. At the XRT position (Starling et al., GCN 6542), we do not detect any afterglow. Assuming the USNO B1.0 star at RA = 02:08:34.67, Dec. = +56:56:22.3 to have I = 15.44, we derive the following upper limit for the image: date time (days) exp. time Ic limit 070617.00838 0.32119 600 20.3 We caution that, as Starling et al. (GCN 6542) noted, this is very close to a star in the USNO B1.0 catalog. Thus, the true limiting magnitude at the XRT position is much shallower than what is stated above. Judging from the early BAT/XRT light curve, this is a real GRB that happens to lie close to a bright star by chance. As the field is crowded, the probability of such a chance alignement is non-negligible. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6546 SUBJECT: Swift/UVOT observations of GRB070616 DATE: 07/06/17 02:38:44 GMT FROM: Massimiliano de Pasquale at MSSL-UCL M. De Pasquale (MSSL/UCL), R. Starling (Univ. Leicester) and P. Schady (MSSL/UCL) report, on the behalf ot the Swift UVOT team: The Swift UVOT telescope began its White filter finding chart exposure of GRB070616 (Starling et al., GCN circ 6542) 144 seconds after the trigger. The XRT position lies on a bright object, listed in the USNO-B1.0 catalogue, therefore we caution that this source strongly affects the photometry. In the XRT error circle we do not detect any optical afterglow. We derive the following 3 sigma upper limits: Filter Time after trigger (s) Exposure (s) 3s U.L. White 144-243 98 18.3 V 250-649 390 18.1 White 144-979 209 18.6 V 250-1122 547 18.3 B 729-738 10 17.1 U 707-874 39 17.2 UW1 680-850 39 17.1 UM2 655-825 39 17.3 UW2 758-777 20 17.0 No correction has been made for the high Galactic reddening of E(B-V)=0.4. We note that this value should be taken with caution, having the burst occurred at low Galactic latitude. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6547 SUBJECT: GRB 070616: BTA optical observations DATE: 07/06/17 05:52:23 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia T. Fatkhullin, V. Sokolov (SAO-RAS, Russia), E. Sonbas (Cukurova Univ., Turkey), A. de Ugarte Postigo, M. Jelínek, J. Gorosabel (IAA-CSIC, Spain), D. Pérez-Ramírez (Univ. de Jaén, Spain), S. Guziy (Nikolaev St. Univ., Ukraine) and A. J. Castro-Tirado (IAA-CSIC, Spain), report: "Following the detection by SWIFT of GRB 070616 (Starling et al. GCNC 6542), we have obtained single VRI frames at the 6m BTA SAO-RAS telescope at Nizhnij Arkhyz (Russia), starting at 23:57 UT (i.e. 7.5 hr after the event). Within the SWIFT/XRT error box , we detect in all filters a faint (R ~ 22), reddened point-like source. Preliminary astrometry yielded RA (J2000) = 02 08 36.00; Dec (J2000) = +56 56 41.0 (+/- 1"), a position very close to the USNO B-1 star reported by Kann et al. (GCNC 6545). Further observations are needed to confirm if this is the optical afterglow to GRB 070616. " This message can be quoted. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6548 SUBJECT: GRB 070616: BTA astrometry and finding chart DATE: 07/06/17 09:52:58 GMT FROM: Antonio Deugarte at IAA-CSIC A. de Ugarte Postigo (IAA-CSIC) T. Fatkhullin (SAO-RAS, Russia), A. J. Castro-Tirado (IAA-CSIC, Spain) on behalf of a larger collaboration report: "We have redone astrometry of the optical afterglow candidate reported by Fatkhullin et al. (GCNC 6547) for GRB 070616 (Starling et al. GCNC 6542). The updated position for the object is (J2000, +/- 0.5"): R.A.: 02:08:36.12 Dec. +56:56:39.7 A finding chart can be found at: http://www.iaa.es/~deugarte/GRBs/070616/GRB070616.gif " This message can be quoted. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6550 SUBJECT: GRB 070616: Swift XRT refined circular DATE: 07/06/17 10:52:11 GMT FROM: Rhaana Starling at U of Leicester R.L.C. Starling (U. Leicester) reports, on behalf of the Swift XRT team: We have analysed the first eight orbits of Swift XRT data (18.6 ks of data out to T0+5.8E4s) for GRB 070616 (Starling et al., GCN Circ. 6542). Using 1.1 ks of overlapping XRT PC mode data and UVOT V-band data, we obtain an astrometrically corrected X-ray position (using the USNO-B1 catalogue) of RA(J2000) = 02 08 36.70 Dec(J2000)= +56 56 43.9 with an error of 2.3 arcseconds (radius, 90% containment). This is 3.7 arcsec from the initially reported XRT position and 6.4 arcsec from the BAT position (GCN Circ. 6542), and 6.3 arcsec from the possible optical transient reported in De Ugarte Postigo et al. (GCN Circ. 6548). The error circle overlaps with the USNO-B1.0 source noted in GCN Circ. 6542. The lightcurve began with a constant flux up to T0+536s, and then decayed with alpha=-4.6 until about T0+1000s. A steep decay follows this, though there are not enough data to accurately measure its slope. After T0+1400s the decay continues with a shallower slope of alpha=-1.2. Several small flares appear on top of the continuum emission up to T0+1000s, some of which may be simultaneous with BAT peaks. The PC mode spectrum including 14.6 ks of data from the second orbit onwards is well fit with a power law of photon index Gamma=2.4+0.2,-0.1 (90%) absorbed only by the large Galactic column of 3.4E21 cm^-2. The 0.3-10 keV observed (unabsorbed) flux is 2.2E-12 (4.0E-12) erg/cm^2/s, corresponding to a count rate of 4.9E-02 count/s. The predicted fluxes at T0+24h and T0+48h are 2.3E-13 and 9.9E-14 erg/cm^2/s respectively, assuming the decay continues with alpha=-1.2. This is an official product of the Swift XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6551 SUBJECT: GRB 070616, Swift-BAT further refined analysis DATE: 07/06/17 16:53:05 GMT FROM: Scott Barthelmy at NASA/GSFC G. Sato (GSFC/ISAS) and S. Barthelmy (GSFC) on behalf of the Swift-BAT team: The time-averaged spectrum from T-2.6 to T+602.2 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.61 +- 0.04. The fluence in the 15-150 keV band is 1.92 +- 0.03 x 10^-5 erg/cm2. The 1-sec peak photon flux measured from T+139.74 sec in the 15-150 keV band is 1.9 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The mask-weighted light curve shows many peaks. The burst started with a low-level smooth emission at ~T-55 sec continuing smoothly and increasing slowly until ~T+100 sec when the main emission started. The main peak is at T+120 sec. Smaller overlapping peaks continue out past T+550 sec. In particular, there is a small peak from T+730 to T+850 sec which is coincident with a peak (flare) in the XRT lightcurve (Fig 2, GCN Report 66.1, Starling et al.). T90 (15-350 keV) is 402 +- 10 sec (estimated error including systematics). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6552 SUBJECT: GRB070616: Optical Observation by MITSuME Okayama DATE: 07/06/18 05:05:26 GMT FROM: Michitoshi Yoshida at Okayama Astrophysical Obs M. Yoshida, K. Yanagisawa, Y. Shimizu, S. Nagayama (OAO, NAOJ) and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We performed optical imaging observation (g', Rc, and Ic) of the field of GRB 070616 (Starling et al. GCN 6542) with 50cm MITSuME telescope at Okayama Astrophysical Observatory from UT 18:04:40 (1h 35m after burst) to UT 18:10:30 on June 16 2007. We coadded 5 CCD frames for each band. Exposure time of each frame is 1 minute. We made flux calibration using USNO B1.0 catalg. We could not identify new source at the position of the afterglow candidate reported by Fatkhullin et al. (GCN 6547) and Ugarte Postigo (GCN 6548). Three sigma limiting magnitudes of our observation are listed below. ---------------------------------------------------- band mid-UT (2007) exp.time upper limit g' June 16 18:07:35 5 x 1 min. 19.5 mag Rc June 16 18:07:35 5 x 1 min. 18.9 mag Ic June 16 18:07:35 5 x 1 min. 18.4 mag ---------------------------------------------------- //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6554 SUBJECT: GRB070616: Optical Observation by MITSuME Akeno DATE: 07/06/18 06:36:35 GMT FROM: Nobuyuki Kawai at Tokyo Tech T. Ishimura, Y. Yatsu, T. Shimokawabe, N. Vasquez, Y.kudo, and N. Kawai (TokyoTech) report on behalf of the MITSuME collaboration: We observed the error box of GRB070616 (Starling et al. GCN 6542) with the 3-color 50cm MITSuME Telescope at Akeno, Japan starting at 16:52:26 June 16 UT, 22m53s after the trigger under a poor sky condition with clouds and a high airmass. In the co-added images of Ic, Rc, and g' bands, we did not detect any afterglow candidate in the XRT error circle. The 3-sigma limiting magnitudes based on USNO-B1.0 (I-band) and NOMAD (R-band,g'-band) stars are following. Filter start time end time Exposure Mag (3-sigma upper limit) ----------------------------------------------------------------- g' 16:52:26 18:03:39 58 x 60 s 17.8 Rc 16:52:26 18:03:39 58 x 60 s 19.1 Ic 16:52:26 18:03:39 58 x 60 s 18.6 ----------------------------------------------------------------- //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6557 SUBJECT: Swift/UVOT detection of GRB070616 optical afterglow. DATE: 07/06/19 20:31:32 GMT FROM: Massimiliano de Pasquale at MSSL-UCL M. De Pasquale (MSSL/UCL), R. Starling (Univ. Leicester), F. E. Marshall (NASA/GSFC), S. Holland (CREEST/USRA/GSFC), P. Schady (MSSL/UCL), M.J. Page (MSSL/UCL) report, on the behalf of the UVOT team: After a careful investigation of the refined XRT error circle of GRB070616 (Starling et al, GCN circ 6550), which contains the bright (V=14.4) star USNO-B1.0 1469-0076513, we find good evidence to suggest that the optical afterglow is detected in the early Swift/UVOT observations. The count rates in V and U band exposures between 250 and 1050 seconds after the trigger show a significant excess (at the 10 sigma level in the V band combined image and at the 5 sigma level in the U band combined image) with respect to late observations (T>1 day). This excess corresponds to an optical source of V=16.5 and U=16.9. The source appears to have disappeared in exposures taken later than 1100s, thus suggesting a drop in the optical flux suggestive of a GRB afterglow behaviour. We obtain a 3 sigma upper limit of V>17.9 at T= 6ks after the trigger. The blended image of the star plus the afterglow is extended compared to other stars in the image. Fitting it with two point sources indicates that the afterglow is about 1.8" west and 0.9" north of USNO-B1.0 star with a statistical uncertainty of ~0.3" in each axis (90% confidence). A detection of the afterglow in the U band indicates a redshift less than ~3. Analysis of another star in the same field of view reveals no change of flux throughout the observations, thus ruling out instrumental effects. While we cannot completely exclude that the star in the XRT error circle might have varied mimicking a GRB afterglow, observations carried out for the further 2 days suggest a constant source. Furthermore, the UV magnitudes of the star in the XRT error circle do not show any significant variation corresponding to those seen in the optical filters, thus supporting the afterglow hypothesis. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6578 SUBJECT: GRB 070616: Suzaku/WAM observation of the prompt emission DATE: 07/06/26 07:51:35 GMT FROM: Makoto Tashiro at Saitama U/Swift K. Morigami, N. Kodaka, K. Onda, M. Tashiro, M. Suzuki, Y. Urata, A. Endo (Saitama U.), T. Uehara, M. Ohno, T. Takahashi, Y. Fukazawa, C. Kira (Hiroshima U.), T. Enoto, R. Miyawaki, K. Nakazawa, K. Makishima (Univ. of Tokyo), K. Yamaoka, Y. E. Nakagawa, S. Sugita (Aoyama Gakuin U.), T. Tamagawa, Y. Terada (RIKEN), S. Hong (Nihon U.), M. Kokubun, M. Suzuki, T. Takahashi (ISAS/JAXA), E. Sonoda, M.Yamauchi, S. Maeno, H. Tanaka, R. Hara (Univ. of Miyazaki), and Suzaku WAM team report: The long burst, GRB 070616 (Swift/BAT trigger #282445; Starling et al., GCN circ 6542; Sakamoto et al., GCN circ 6543; Starling et al., GCN Report 66.2) triggered the Suzaku Wide-band All-sky Monitor (WAM) covering 50 keV to 5 MeV at 16:31:50 UT (T0), which was 137 second after the Swift/BAT trigger time. Since The WAM BST mode data did not cover the Swift/BAT trigger time, we employed continuous monitoring (TRN) data to evaluate the whole light curve and the averaged spectrum of the burst. The observed light curve exhibits multiple peaked structures preceded by a precursor-like emission (from T0-163 to T0-158 seconds). Although Starling et al. reported a very long duration, over 600 seconds (GCN Report 66.1), the Suzaku/WAM covered only 140 seconds from the start of the main peaks before the entry of the SAA region in the orbit. The derived fluence in 100-1000 keV was more than 6.6 (-0.6, +0.7) x 10^-6 erg/cm^2. The 1-s peak flux was 1.40 (-0.17,+0.16) photons/cm^2/s in the same energy range. Preliminary result shows that the time-averaged spectrum from T0-10 to T0+30 seconds is well fitted with a single power-law of a photon index Gamma = 2.36 (-0.12, +0.12) in the 100-1000 keV energy range. All the quoted errors are at statistical 90% confidence level, while the systematic errors are not considered. The light curve data for this burst is available at the following web site. http://www.astro.isas.ac.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6579 SUBJECT: GRB 070616 : WIDGET simultaneous optical observations DATE: 07/06/26 08:03:05 GMT FROM: Makoto Tashiro at Saitama U/Swift N. Kodaka, K. Onda, Y. Urata, W. Iwakiri, T. Sugasahara, M. Tashiro (Saitama-U), M. Kuwahara (TUS/RIKEN), T. Tamagawa (RIKEN) F. Usui (ISAS/JAXA) report: "We observed the error region of GRB 070616 (Swift/BAT trigger #282445; Starling et al., GCN 6542; Sakamoto et al., GCN circ 6543; Starling et al., GCN Report 66.2) with the very wide-field camera WIDGET located at Kiso, Japan. The WIDGET monitored the region with repeat of unfiltered 5-second exposures between 27 seconds before and 136 seconds after the burst. We did not find any optical emission from the afterglow position (Fatkhullin et al. GCN 6547). The 1-sigma limiting magnitude of each frame derived by the Tycho-2 catalog was around V=11.8 magnitudes." This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 6629 SUBJECT: GRB 070616: No Evidence for I Band Afterglow DATE: 07/07/15 16:06:28 GMT FROM: Alexander Kann at TLS Tautenburg D. A. Kann & A. C. Wilson (TLS Tautenburg) report: We reobserved the field of GRB 070616 (Starling et al., GCN 6542) with the Tautenburg 1.34m Schmidt telescope. We obtained 6 x 300 second images in the I band in good observing conditions but with a few passing clouds. Using the same USNOB1.0 star as used by Kann et al. (GCN 6545), we determine the following limiting magnitude: date time (days) exp. time Ic limit 070715.00750 28.32031 6 x 300 21.6 Using this star and three other unsaturated, isolated stars, we determine differential magnitudes between the star that is blended with the afterglow (de Pasquale et al., GCN 6557) and these stars at both epochs. We find that between the two epochs the star has become fainter by 0.064, 0.023, 0.041 and 0.001 magnitudes in comparison to the other four stars. The typical errors are 0.02 magnitudes. We therefore conclude that we detect no significant fading between epoch one (star + possibly blended afterglow) and epoch two (star only), placing a limit of Ic > 20 on the afterglow at the first epoch (Kann et al., GCN 6545). This message may be cited.