//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13602 SUBJECT: GRB 120807A: Swift detection of a burst DATE: 12/08/07 07:23:44 GMT FROM: David Palmer at LANL F. E. Marshall (NASA/GSFC), P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), B.P. Gompertz (U Leicester), C. Guidorzi (U Ferrara), J. A. Kennea (PSU), O. M. Littlejohns (U Leicester), C. B. Markwardt (NASA/GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL) and E. Troja (NASA/GSFC/ORAU) report on behalf of the Swift Team: At 07:09:37 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 120807A (trigger=530267). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 241.211, -47.490 which is RA(J2000) = 16h 04m 51s Dec(J2000) = -47d 29' 23" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single peak structure with a duration of about 15 sec. The peak count rate was ~2000 counts/sec (15-350 keV), at ~2 sec after the trigger. The XRT began observing the field at 07:10:49.4 UT, 71.6 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source with an enhanced position: RA, Dec 241.2594, -47.4797 which is equivalent to: RA(J2000) = 16h 05m 02.26s Dec(J2000) = -47d 28' 47.0" with an uncertainty of 2.3 arcseconds (radius, 90% containment). This location is 123 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. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (4.94 x 10^21 cm^-2, Kalberla et al. 2005), with an excess column of 3.5 (+4.80/-2.19) x 10^21 cm^-2 (90% confidence). UVOT took a finding chart exposure of 150 seconds with the White filter starting 75 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 large, but uncertain extinction expected. Burst Advocate for this burst is F. E. Marshall (marshall 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: 13603 SUBJECT: GRB 120807A: Enhanced Swift-XRT position DATE: 12/08/07 11:02:53 GMT FROM: Phil Evans at U of Leicester A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team. Using 1862 s of XRT Photon Counting mode data and 2 UVOT images for GRB 120807A, 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 = 241.26016, -47.47972 which is equivalent to: RA (J2000): 16h 05m 2.44s Dec (J2000): -47d 28' 47.0" 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: 13604 SUBJECT: GRB 120807A: Swift-BAT refined analysis DATE: 12/08/07 11:58:57 GMT FROM: Scott Barthelmy at NASA/GSFC J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team): Using the data set from T-60 to T+243 sec from recent telemetry downlinks, we report further analysis of BAT GRB 120807A (trigger #530267) (Marshall, et al., GCN Circ. 13602). The BAT ground-calculated position is RA, Dec = 241.273, -47.455 deg, which is RA(J2000) = 16h 05m 05.6s Dec(J2000) = -47d 27' 16.3" with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 89%. The mask-weighted light curves shows a single pulse starting at ~T-5 sec, peaking at ~T+2 sec, and ending at ~T+20 sec. T90 (15-350 keV) is 20.0 +- 5.8 sec (estimated error including systematics). The time-averaged spectrum from T-0.24 to T+24.07 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.81 +- 0.30. The fluence in the 15-150 keV band is 2.9 +- 0.5 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+0.65 sec in the 15-150 keV band is 0.9 +- 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/530267/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13605 SUBJECT: GRB 120807A: TAROT La Silla observatory optical observations DATE: 12/08/07 14:39:04 GMT FROM: Alain Klotz at CESR-CNRS Klotz A. (IRAP-CNRS-OMP), Gendre B. (ASDC/INAF-OAR), Boer M. (UNS-CNRS-OCA), Atteia J.L. (IRAP-CNRS-OMP) report: We imaged the field of GRB 120807 detected by SWIFT (trigger 530267) with the TAROT robotic telescope (D=25cm) located at the European Southern Observatory, La Silla observatory, Chile. The observations started 31.5s after the GRB trigger (15.2s after the notice). The elevation of the field decreased from 8 degrees above horizon and weather conditions were poor (due to the low elevation). The first image is trailed with a duration of 60.0s (see the description in Klotz et al., 2006, A&A 451, L39). We do not detect any OT in the enhanced Swift-XRT position (Evans et al. GCNC 13603) with a limiting magnitude of: t0+31.5s to t0+91.5s : R > 15.5 Further images does not show OT anymore at about the same limiting magnitude until 1500 seconds after the trigger. Magnitudes were estimated with the nearby USNO-B1 stars and are not corrected for galactic dust extinction. N.B. Galactic coordinates are lon=333.3260 lat= +3.6420 and the galactic extinction in R band is about 4 magnitudes estimated from D. Schlegel et al. 1998ApJ...500..525S. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13607 SUBJECT: GRB 120807A: RAPTOR Limits During Gamma-Ray Emitting Interval DATE: 12/08/07 17:15:41 GMT FROM: James Wren at LANL J. Wren, W.T. Vestrand, P. Wozniak, and H. Davis, of Los Alamos National Laboratory report: A RAPTOR wide-field monitor located in Maui observed the location of Swift trigger 530267 (Marshall et al., GCN 13602) during the period that the Swift BAT was observing gamma-ray emission. The 10 s exposure began at 07:09:38.7 UTC -- 1 s after the Swift trigger and 1 s before the gamma-ray emission reached peak intensity. We detect no new object at the location of the refined Swift XRT location (Beardmore et al., GCN 13603) to a 3-sigma limiting magnitude of 10.3. Our unfiltered images are calibrated to the Tycho-2 V-band. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13608 SUBJECT: GRB 120807A: Fermi/LAT upper limit DATE: 12/08/07 22:00:53 GMT FROM: Weikang Zheng at U.of Michigan Weikang Zheng and Carl Akerlof (Umich), report on behalf of the ROTSE collaboration: We analyzed Fermi/LAT data of GRB 120807A (Marshall et al., GCN 13602) as a follow-up of routine search in Swift trigger catalogs in our LAT data processing pipeline using both the matched filter technique (Akerlof et al. 2010, ApJ, 725, L15; 2011 ApJ, 726, 22; 2012, arXiv:1205.3066; Zheng et al. 2012, ApJ 745,72; 2012, arXiv:1203.5113) and likelihood method. We do NOT detect high energy photon emission from both methods by using a standard data selection (with Energy above 100 MeV) in 47.5s duration. The burst location was about 50 degree from the LAT boresight, and the zenith angle was about 96 degrees at trigger time. This location is very close to Galactic plane (gb = 333.3 and gb= 3.6 degree). Using the likelihood method, we estimated the upper limit in LAT energy range (0.1 - 10 GeV) is 1.27e-05 (photons cm^-2 s^-1) by assuming a spectral index of -2.2. The pipeline result is given in the following link: http://rotse.net/LAT/SwiftTriggers/366016180/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13610 SUBJECT: GRB 120807A: Swift-XRT refined Analysis DATE: 12/08/08 07:24:06 GMT FROM: Phil Evans at U of Leicester A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), O.M. Littlejohns (U. Leicester), G. Stratta (ASDC), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), J.A. Kennea (PSU), M.C. Stroh (PSU), D.N. Burrows (PSU) and F.E. Marshall report on behalf of the Swift-XRT team: We have analysed 2.9 ks of XRT data for GRB 120807A (Marshall et al. GCN Circ. 13602), from 56 s to 75.9 ks after the BAT trigger. The data comprise 8 s in Windowed Timing (WT) mode (taken while Swift was slewing), with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN. Circ 13603). The light curve can be modelled with a power-law decay with a decay index of alpha=1.29 (+0.15, -0.16). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.3 (+/-0.3). The best-fitting absorption column is 1.04 (+0.25, -0.22) x 10^22 cm^-2, in excess of the Galactic value of 4.9 x 10^21 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.8 x 10^-11 (1.4 x 10^-10) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.04 (+0.25, -0.22) x 10^22 cm^-2 Galactic foreground: 4.9 x 10^21 cm^-2 Excess significance: 4.1 sigma Photon index: 2.3 (+/-0.3) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00530267. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13616 SUBJECT: GRB 120807A: Swift/UVOT Upper Limits DATE: 12/08/10 14:32:49 GMT FROM: Mike Siegel at PSU/Swift MOC GRB 120807A: Swift/UVOT Upper Limits M. H. Siegel (PSU) and F. E. Marshall (NASA/GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 120807A 75 s after the BAT trigger (Marshall et al., GCN Circ. 13602). No optical afterglow consistent with the XRT position (Beardmore et al., GCN Circ. 13603) 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 75 225 147 >20.6 u_FC 288 537 246 >20.4 white 75 1884 431 >21.8 v 618 1935 156 >19.6 b 543 1860 136 >20.4 u 288 1835 363 >20.7 w1 668 1810 136 >20.3 m2 1591 1611 19 >18.8 w2 593 1910 117 >19.9 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 1.41 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13776 SUBJECT: Corrections to the Fermi-LAT upper limits for GRB 120807A, 120908A, 120909A, and 120911A DATE: 12/09/17 21:22:46 GMT FROM: Weikang Zheng at U.of Michigan Weikang Zheng and Carl Akerlof (Umich), report on behalf of the ROTSE collaboration (the authors are not affiliated with the Fermi Collaboration), The recent GCN Circulars we reported about Fermi-LAT upper limits for GRB 120807A (GCN 13608), 120908A (GCN 13742), 120909A (GCN 13742), and 120911A (GCN 13752) contain an error about the upper limits estimation due to a wrong method. We apologize for the confusion. We thank Giacomo Vianello from LAT group for pointing it out and making suggestion to correct it. We've updated our pipeline result with the appropriate method (see The Fermi LAT team, Ackermann et al., 2012, ApJ, 754, 121). We report the corrected upper limit result (100 MeV -300 GeV; T0-T0 +47.5s) for the 4 GRBs again: GRB 120807A : 5.42e-05 ph/cm2/s GRB 120908A : 1.79e-04 ph/cm2/s GRB 120909A : 8.70e-05 ph/cm2/s GRB 120911A : 3.81e-05 ph/cm2/s