//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13661 SUBJECT: GRB 120817A: Swift detection of a burst DATE: 12/08/17 06:58:40 GMT FROM: David Palmer at LANL B.P. Gompertz (U Leicester), P. A. Evans (U Leicester), C. Guidorzi (U Ferrara), K. L. Page (U Leicester), D. M. Palmer (LANL) and R. L. C. Starling (U Leicester) report on behalf of the Swift Team: At 06:49:42 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 120817A (trigger=531267). Swift could not immediately slew due to an Earth limb pointing constraint. The BAT on-board calculated location is RA, Dec 250.706, -38.340 which is RA(J2000) = 16h 42m 49s Dec(J2000) = -38d 20' 25" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multiple-peaked structure with a duration of about 25 sec. The peak count rate was ~1700 counts/sec (15-350 keV), at ~0 sec after the trigger. Due to an observing constraint, Swift will not slew until T0+50.1 minutes. There will be no XRT or UVOT data until this time. Burst Advocate for this burst is B.P. Gompertz (bpg6 AT le.ac.uk). 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: 13662 SUBJECT: GRB 120817A: Swift-XRT observations DATE: 12/08/17 08:45:10 GMT FROM: Phil Evans at U of Leicester M. Perri (ASDC), G. Tagliaferri (INAF-OAB), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), D.N. Burrows (PSU) and J.A. Kennea (PSU) report on behalf of the Swift-XRT team: The XRT began observing the field of GRB 120817A at 07:41:33.5 UT, 3110.8 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 250.69098, -38.35404 which is equivalent to: RA(J2000) = 16h 42m 45.84s Dec(J2000) = -38d 21' 14.5" with an uncertainty of 4.2 arcseconds (radius, 90% containment). This location is 65 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 consistent with the Galactic value of 2.88 x 10^21 cm^-2 (Kalberla et al. 2005). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13664 SUBJECT: GRB 120817A: FTN and FTS observations DATE: 12/08/17 11:02:47 GMT FROM: Cristiano Guidorzi at Ferrara U,Italy C. Guidorzi (U. Ferrara), C.G. Mundell, C.J. Mottram, F. Virgili (LJMU), A. Gomboc (U. Ljubljana) report on behalf of a larger collaboration: The 2-m Faulkes Telescope North (FTN) automatically began observing GRB 120817A (Gompertz et al. GCN Circ. 13661) on August 17 2012, 06:53:57 UT corresponding to 4.2 minutes post burst trigger with BVRi' filters. Within the XRT error circle (Perri et al. GCN Circ. 13662), close to a USNOB1 object we detect a faint, uncatalogued, possibly fading source at the following position R.A. = 16:42:45.92 Dec = -38:21:12.4 (J2000) with an uncertainty of about 1". The detection is marginal, with an estimated magnitude of 19.3 +/- 0.4 in the R band at a mean time of 17.4 minutes (60 s exposure) calibrated against nearby USNOB-1 stars. The 2-m Faulkes Telescope South (FTS) began observing at 77 min post burst. In a stacked R-band frame we find marginal evidence for fading, with R=19.8 +- 0.3 mag at a mean time of 105 min (total exposure of 360 s). The nearby USNOB1 object is compatible with being constant between the two observations. The comparison between the FTN and FTS R-band images is available at http://www.fe.infn.it/u/guidorzi/GRB120817A_XRT_FT_candidate.jpg //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13667 SUBJECT: GRB 120817A: Enhanced Swift-XRT position DATE: 12/08/17 15:09:04 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 2321 s of XRT Photon Counting mode data and 5 UVOT images for GRB 120817A, 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 = 250.68918, -38.35451 which is equivalent to: RA (J2000): 16h 42m 45.40s Dec (J2000): -38d 21' 16.2" 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: 13669 SUBJECT: GRB 120817A: Swift-BAT refined analysis DATE: 12/08/17 18:23:39 GMT FROM: Scott Barthelmy at NASA/GSFC D. M. Palmer (LANL), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), B.P. Gompertz (U Leicester), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), 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 the recent telemetry downlink, we report further analysis of BAT GRB 120817A (trigger #531267) (Gompertz, et al., GCN Circ. 13661). The BAT ground-calculated position is RA, Dec = 250.692, -38.377 deg, which is RA(J2000) = 16h 42m 46.2s Dec(J2000) = -38d 22' 36.8" with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 85%. The mask-weighted light curve shows two slighly overlapping peaks starting at ~T-2 sec, peaking at ~T+0.0 and ~T+11 sec, with a tail ending at ~T+65 sec. T90 (15-350 keV) is 28.2 +- 6.8 sec (estimated error including systematics). The time-averaged spectrum from T-2.24 to T+30.77 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.97 +- 0.16. The fluence in the 15-150 keV band is 6.9 +- 0.6 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T-0.12 sec in the 15-150 keV band is 0.8 +- 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/531267/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13673 SUBJECT: GRB 120817A: Swift-XRT refined Analysis DATE: 12/08/18 09:13:22 GMT FROM: Phil Evans at U of Leicester B.P. Gompertz (U Leicester) reports on behalf of the Swift-XRT team: We have analysed 9.7 ks of XRT data for GRB 120817A (Gompertz et al. GCN Circ. 13661), from 3.1 ks to 22.9 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN. Circ 13667). The light curve can be modelled with a power-law decay with a decay index of alpha=0.70 (+/-0.18). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.0 (+0.4, -0.3). The best-fitting absorption column is 5.9 (+2.6, -1.9) x 10^21 cm^-2, in excess of the Galactic value of 2.9 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 (8.9 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 5.9 (+2.6, -1.9) x 10^21 cm^-2 Galactic foreground: 2.9 x 10^21 cm^-2 Excess significance: 2.5 sigma Photon index: 2.0 (+0.4, -0.3) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00531267. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13694 SUBJECT: GRB 120817A: RAPTOR Limits During Gamma-Ray Emitting Interval DATE: 12/08/20 16:27:28 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 531267 (Gompertz et al., GCN 13661) during the period that the Swift BAT was observing gamma-ray emission. The 10 s exposure began at 06:49:38.0 UTC -- 4 s before the Swift trigger. We detect no new object at the location of the refined Swift XRT location (Gompertz et al., GCN 13673) to a 3-sigma limiting magnitude of 10.3. Our unfiltered images are calibrated to the Tycho-2 V-band. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13701 SUBJECT: GRB 120817A: Swift/UVOT Upper Limits DATE: 12/08/27 23:33:50 GMT FROM: Stefan Immler at NASA/GSFC S. Immler (NASA/CRESST/GSFC) and B. P. Gompertz (U Leicester) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 120817A 3115 s after the BAT trigger (Gompertz et al., GCN Circ. 13661). No optical afterglow consistent with the XRT (Beardmore et al., GCN 13667) or the FTN positions (Guidorzi et al., GCN 13664) 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 3115 3265 147 >19.4 white 3115 4496 344 >20.4 v 3272 10816 1278 >20.2 b 4092 17166 945 >21.1 u 3887 22943 1904 >21.1 w1 3682 22294 2164 >20.3 m2 3476 21386 1838 >20.2 w2 4503 9902 1082 >20.0 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.84 in the direction of the burst (Schlegel et al. 1998).