//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10983 SUBJECT: GRB 100725B: Swift detection of a burst DATE: 10/07/25 11:39:50 GMT FROM: Wayne Baumgartner at GSFC W. H. Baumgartner (GSFC/UMBC), M. M. Chester (PSU), V. D'Elia (ASDC), J. M. Gelbord (PSU), S. T. Holland (CRESST/USRA/GSFC), N. P. M. Kuin (UCL-MSSL), V. Mangano (INAF-IASFPA), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester), T. A. Pritchard (PSU), J. L. Racusin (NASA/GSFC), B. Sbarufatti (INAF-OAB/IASFPA) and T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team: At 11:24:34 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 100725B (trigger=429969). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 290.026, +76.955 which is RA(J2000) = 19h 20m 06s Dec(J2000) = +76d 57' 17" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multi-peaked structure with a duration of about 160 sec. The peak count rate was ~3500 counts/sec (15-350 keV), at ~140 sec after the trigger. The XRT began observing the field at 11:25:52.4 UT, 77.9 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 290.03471, 76.95639 which is equivalent to: RA(J2000) = 19h 20m 8.33s Dec(J2000) = +76d 57' 23.0" with an uncertainty of 4.3 arcseconds (radius, 90% containment). This location is 9.1 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper. We cannot determine whether the source is fading at the present time. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (5.43e+20 cm^-2, Kalberla et al. 2005), with an excess column of 2.7 (+3.09/-2.62) x 10^21 cm^-2 (90% confidence). The initial flux in the 2.5 s image was 8.20e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 87 seconds after the BAT trigger. No credible 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 19.6 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 expected extinction corresponding to E(B-V) of 0.09. Burst Advocate for this burst is W. H. Baumgartner (wayne 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: 10984 SUBJECT: GRB100725B: Faulkes Telescope North observations DATE: 10/07/25 12:50:26 GMT FROM: David Bersier at Liverpool John Moores U D. Bersier, Z. Cano report on behalf of a larger collaboration: The Faulkes Telescope North located in Hawaii automatically responded to Swift trigger 429969 (GCN 10983) 104 seconds after trigger, in poor seeing conditions. We do not detect any source inside the XRT error circle to the following limits: delta_T exp time lim mag filter 1.75 min 10 sec 17.5 R 11 min 30 sec 18.0 R 17 min 60 sec 18.5 R 27 min 120 sec 18.0 i //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10986 SUBJECT: GRB 100725B: Enhanced Swift-XRT position DATE: 10/07/25 14:30:45 GMT FROM: Phil Evans at U of Leicester M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team. Using 702 s of XRT Photon Counting mode data and 1 UVOT images for GRB 100725B, 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 = 290.03298, +76.95643 which is equivalent to: RA (J2000): 19h 20m 7.92s Dec (J2000): +76d 57' 23.1" with an uncertainty of 1.8 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: 10990 SUBJECT: GRB 100725B: Swift/UVOT Upper Limits DATE: 10/07/25 23:00:52 GMT FROM: Tyler Pritchard at PSU GRB 100725B: Swift/UVOT Upper Limits T. A. Pritchard (PSU) and W. H. Baumgartner (GSFC/UMBC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 100725B 87 s after the BAT trigger (Baumgartner et al., GCN Circ. 10983). No optical afterglow consistent with the XRT position (Goad et al., GCN Circ. 10986) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white(FC) 87 237 147 >20.8 u(FC) 300 549 246 >20.4 white 87 6844 664 >21.4 v 629 5882 244 >19.6 b 555 6703 432 >20.5 u 300 6498 659 >20.2 w1 678 6293 432 >20.3 m2 653 6088 432 >20.1 w2 605 5677 255 >20.1 The values quoted above are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.09 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10992 SUBJECT: GRB 100725B: refined XRT analysis DATE: 10/07/26 11:41:00 GMT FROM: Boris Sbarufatti at INAF-OAB/IASFPA V. Mangano (INAF IASF-PA), B. Sbarufatti (INAF OAB/INAF IASF-PA) and W. H. Baumgartner (GSFC/UMBC) report on behalf of the Swift-XRT team: We have analysed 10 ks of XRT data for GRB 100725B (Baumgartner et al. GCN Circ. 10983), from 68 s to 58.8 ks after the BAT trigger. The data comprise 288 s in Windowed Timing (WT) mode (the first 8 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The light curve shows flaring activity for the initial 300 s (i.e. the WT observation), then can be modeled with a series of power-law decays and a small Gaussian flare. The initial decay index is alpha=4.66 (+0.4 -0.2). The Gaussian flare peaks at T+780 (+/-37) s with a sigma of 145 (+/- 30) s. At T+770 s the decay change in a possible slow rise with an alpha of 0.30 (+/- 0.27) before breaking again at T+8660 s to a final decay with index alpha=1.3 (+/- 0.2). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.75 (+/-0.06). The best-fitting absorption column is 4.7 (+0.4, -0.3) x 10^21 cm^-2, in excess of the Galactic value of 5.4 x 10^20 cm^-2 (Kalberla et al. 2005). The PC mode spectrum (extracted from T+359 s to T+6761 s, 2.9 ks exposure) has a photon index of 2.5 (+/-0.2) and a best-fitting absorption column of 5.1 (+0.7, -0.6) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.1 x 10^-11 (1.1 x 10^-10) erg cm^-2 count^-1. If the light curve continues to decay with a power-law decay index of 1.3, the count rate at T+48 hours will be 4.3 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.8 x 10-13 (4.7 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/00429969. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10993 SUBJECT: GRB 100725B: Swift-BAT refined analysis DATE: 10/07/26 12:37:13 GMT FROM: Scott Barthelmy at NASA/GSFC T. Sakamoto (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+609 sec from recent telemetry downlinks, we report further analysis of BAT GRB 100725B (trigger #429969) (Baumgartner, et al., GCN Circ. 10983). The BAT ground-calculated position is RA, Dec = 290.029, 76.955 deg, which is RA(J2000) = 19h 20m 07.0s Dec(J2000) = +76d 57' 17.6" with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 28%. The mask-weighted light curve shows several peaks starting at ~T-10 sec, peaking at ~T+10, T+60, T+90, T+130, and T+220 sec, and ending at ~T+240 sec. T90 (15-350 keV) is 200 +- 30 sec (estimated error including systematics). The time-averaged spectrum from T-4.8 to T+226.1 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.89 +- 0.06. The fluence in the 15-150 keV band is 6.8 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+132.41 sec in the 15-150 keV band is 2.4 +- 0.1 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/429969/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10997 SUBJECT: GRB100725B: MITSuME optical upper limits DATE: 10/07/27 00:28:17 GMT FROM: Daisuke Kuroda at OAO/NAOJ D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ), S. Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto) and N. Kawai(Tokyo Tech) report on behalf of the MITSuME collaboration: We observed the field of GRB 100725B (Baumgartner et al. GCNC 10983) with the optical three color (g', Rc and Ic) CCD camera attached to the MITSuME 50cm telescope of Okayama Astrophysical Observatory. The observation started on 2010-07-25 14:05:46 UT (~2.7 h after the burst). We did not find any new point source within the XRT error circle (Goad et al., GCNC 10986) in all the three bands. Three sigma upper limits of the OT are listed below. We used SDSS catalog for flux calibration. T0+[day] MID-UT T-EXP[sec] g' Rc Ic ------------------------------------------------------ 0.13892 14:44:37 7620.0 >19.7 >19.3 >18.7 ------------------------------------------------------ T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11030 SUBJECT: GRB 100725B: TELMA optical observation DATE: 10/07/30 16:26:49 GMT FROM: Sergey Guziy at IAA CSIC J. C. Tello, R. Sánchez, M. Jelínek, P. Kubánek, S. Guziy, A. J. Castro-Tirado (IAA-CSIC Granada) on behalf of a larger collaboration report: "Following the detection of GRB 100725B by Swift (Baumgartner et al. GCNC 10983), we have obtained optical images with the 0.6m TELMA robotic telescope at the BOOTES-2 station located in Southern Spain. At the position of the X-ray afterglow detected by SWIFT/XRT (Goad et al. GCNC 10986) we do not detect any optical source down to i' < 19 in the co-added 187 images (60-s each, using an i' band filter, at 20:41 UT, i.e. 9.3-hr after the onset of the burst). This message can be quoted. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11149 SUBJECT: GRB 100725B: Maidanak optical upper limit DATE: 10/08/27 14:11:00 GMT FROM: Alina Volnova at SAI MSU A. Volnova (SAI MSU), A. Pozanenko (IKI), B. Satovski (Astrotel), M. Ibrahimov (MAO) report on behalf of larger GRB follow-up collaboration: We observed the field of the Swift GRB 100725B (Baumgartner et al., GCN 10983) with AZT-22 telescope of Maidanak observatory in R-band on Jul.25 between (UT) 16:36:55 - 17:51:54 under good waether conditions (seeing 0.7"). We took 9 images with exposure 300 seconds. We do not detect any sources in enhanced XRT error circle (Goad et al. GCN 10986). The upper limit (3 sigma) of stacked image is based on SDSS-DR7 is the following: t-t0,d filter exp., uplim 0.24295 R 9x300 22.7 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11150 SUBJECT: GRB 100725B: Mondy optical upper limit DATE: 10/08/27 14:11:49 GMT FROM: Alina Volnova at SAI MSU E. Klunko (ISTP), A. Volnova(SAI MSU), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of the Swift GRB 100725B (Baumgartner et al., GCN 10983) with AZT-33IK telescope of Sayan observatory (Mondy) on Jul.25 between (UT) 16:36 - 20:18 under variable weather conditions and mean seeing ~2.0". In the stacked image of the best of 36 images we do not detect any sources in enhanced XRT error circle (Goad et al. GCN 10986). The upper limit (3 sigma) of the stacked image based on SDSS-DR7 field stars is the following: t-t0,d filter exp.,s uplim 0.31128 R 36*90 21.3