//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30447 SUBJECT: GRB 210712A: Swift detection of a burst DATE: 21/07/12 09:58:21 GMT FROM: Hans Krimm at NSF/NASA-GSFC B. Sbarufatti (PSU), H. A. Krimm (NSF) and K. L. Page (U Leicester) report on behalf of the Neil Gehrels Swift Observatory Team: At 09:43:11 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 210712A (trigger=1059881). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 97.337, -35.393 which is RA(J2000) = 06h 29m 21s Dec(J2000) = -35d 23' 33" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single-peaked structure with a duration of about 20 sec, followed by lower-level extended emission. The peak count rate was ~2600 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 09:44:32.5 UT, 80.6 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source with an enhanced position: RA, Dec 97.3319, -35.3717 which is equivalent to: RA(J2000) = 06h 29m 19.66s Dec(J2000) = -35d 22' 18.0" with an uncertainty of 1.9 arcseconds (radius, 90% containment). This position may be improved as more data are received; the latest position is available at https://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 (8.88 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 6.5 (+5.28/-4.30) x 10^21 cm^-2 (90% confidence). The initial flux in the 2.5 s image was 3.52e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 90 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 none of the XRT error circle. 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 0.076. Burst Advocate for this burst is B. Sbarufatti (bxs60 AT psu.edu). 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/) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30453 SUBJECT: GRB 210712A: Enhanced Swift-XRT position DATE: 21/07/12 18:32:40 GMT FROM: Phil Evans at U of Leicester P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team. Using 1702 s of XRT Photon Counting mode data and 4 UVOT images for GRB 210712A, 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 = 97.33177, -35.37165 which is equivalent to: RA (J2000): 06h 29m 19.63s Dec (J2000): -35d 22' 18.0" with an uncertainty of 2.1 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: 30455 SUBJECT: GRB 210712A: BOOTES-3/YA optical upper limit DATE: 21/07/12 21:08:42 GMT FROM: Youdong HU at IAA-CSIC Y.-D. Hu, E. Fernandez-Garcia, T.-R. Sun, A. J. Castro-Tirado, M. D. Caballero-Garcia, M. A. Castro Tirado (IAA-CSIC), I. Carrasco and C. Perez del Pulgar (Univ. de Malaga), and R. Querel (NIWA), on behalf of a larger collaboration, report: The 60cm BOOTES-3/YA robotic telescope at NIWA Lauder in Otago (New Zealand) automatically responded to the Swift trigger of GRB 210712A (Sbarufatti et al. GCNC 30447). Images were taken starting at 15:01 UT, but due to poor weather conditions, only images taken after 17:32 UT (~7.8 hrs after trigger) could be used. In the co-added image (30 exposures 60s each), no source is found at the position reported by Swift/XRT (Evans et al. GCNC 30453) down to 19.6 mag which is consistent with the non-detection by Swift/UVOT (Sbarufatti et al. GCNC 30447). Further observations are ongoing. We thank the staff at NIWA for its excellent support. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30456 SUBJECT: GRB 210712A: Swift/UVOT Upper Limits DATE: 21/07/12 23:12:07 GMT FROM: Mike Siegel at PSU/Swift MOC M. H. Siegel (PSU) and B. Sbarufatti (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 210712A 91 s after the BAT trigger (Sbarufatti et al., GCN Circ. 30447). No optical afterglow consistent with the enhanced XRT position (Evans et al. GCN Circ. 30453) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 91 241 147 >19.5 u_FC 304 554 246 >19.6 white 91 604 167 >19.5 b 560 579 19 >18.0 u 304 554 246 >19.6 w2 609 614 4 >17.5 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.076 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30457 SUBJECT: GRB 210712A: Swift-XRT refined Analysis DATE: 21/07/13 03:01:23 GMT FROM: Phil Evans at U of Leicester D.N. Burrows (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , J. D. Gropp (PSU), J.A. Kennea (PSU) and B. Sbarufatti report on behalf of the Swift-XRT team: We have analysed 8.5 ks of XRT data for GRB 210712A (Sbarufatti et al. GCN Circ. 30447), from 86 s to 44.8 ks after the BAT trigger. The data comprise 164 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN Circ. 30453). The late-time light curve (from T0+5.4 ks) can be modelled with a power-law decay with a decay index of alpha=1.06 (+0.10, -0.09). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.52 (+/-0.06). The best-fitting absorption column is 1.10 (+0.22, -0.21) x 10^21 cm^-2, consistent with the Galactic value of 8.9 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.98 (+0.13, -0.09) and a best-fitting absorption column consistent with the Galactic value. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.3 x 10^-11 (4.0 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 8.9 (+2.9, -0.0) x 10^20 cm^-2 Galactic foreground: 8.9 x 10^20 cm^-2 Excess significance: <1.6 sigma Photon index: 1.98 (+0.13, -0.09) If the light curve continues to decay with a power-law decay index of 1.06, the count rate at T+24 hours will be 0.015 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.9 x 10^-13 (5.9 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/01059881. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30460 SUBJECT: GRB 210712A: Swift-BAT refined analysis DATE: 21/07/13 14:15:12 GMT FROM: Hans Krimm at NSF/NASA-GSFC T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), B. Sbarufatti (PSU), M. Stamatikos (OSU), (i.e. the Swift-BAT team): Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 210712A (trigger #1059881) (Sbarufatti, et al., GCN Circ. 30447). The BAT ground-calculated position is RA, Dec = 97.322, -35.376 deg which is RA(J2000) = 06h 29m 17.3s Dec(J2000) = -35d 22' 32.2" with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 71%. The mask-weighted light curve shows a series of peaks. The first is from roughly T-40 to T-30. Then the strongest peak is from T-5 to T+15. This is followed by a string of weaker peaks from T+20 to T+120. The spacecraft slewed away from the burst location by T+700 sec. T90 (15-350 keV) is 136.41 +- 63.58 sec (estimated error including systematics). The time-averaged spectrum from -39.76 to 174.18 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 1.00 +- 0.53, and Epeak of 51.8 +- 11.6 keV (chi squared 70.95 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 3.0 +- 0.3 x 10^-6 erg/cm2 and the 1-sec peak flux measured from T+0.09 sec in the 15-150 keV band is 2.3 +- 0.3 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.85 +- 0.11 (chi squared 80.11 for 57 d.o.f.). All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/1059881/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30643 SUBJECT: GRB 210712A: Fermi GBM observation DATE: 21/08/13 07:31:38 GMT FROM: Elisabetta Bissaldi at INFN,Bari E. Bissaldi (Politecnico and INFN Bari) reports on behalf of the Fermi GBM Team: "At 09:43:10.98 UT on 12 July 2021, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 210712A (trigger 647775795 / 210712405), which was also detected by the Swift/BAT (Sbarufatti et al. 2021, GCN 30447). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight at the GBM trigger time is 36 degrees. The GBM light curve consists of an emission episode with a duration (T90) of about 8 s (50-300 keV). The time-averaged spectrum from T0-0.3 s to T0+6.6 s is adequately fit by a power law function with an exponential high-energy cutoff. The power law index is -1.04 +/- 0.13 and the cutoff energy, parameterized as Epeak, is 230 +/- 50 keV. The event fluence (10-1000 keV) in this time interval is (1.51 +/- 0.17)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+1.1 s in the 10-1000 keV band is 3.1 +/- 0.2 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"