//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13934 SUBJECT: GRB 121031A: Swift detection of a burst DATE: 12/10/31 23:17:04 GMT FROM: David Palmer at LANL V. D'Elia (ASDC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU), M. M. Chester (PSU), J. R. Cummings (NASA/UMBC), N. Gehrels (NASA/GSFC), S. T. Holland (STScI), J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC) and D. M. Palmer (LANL) report on behalf of the Swift Team: At 22:50:30 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 121031A (trigger=537195). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 170.771, -3.511 which is RA(J2000) = 11h 23m 05s Dec(J2000) = -03d 30' 37" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a large peak with several smaller peaks riding on top with a total duration of about 50 sec. The peak count rate was ~4000 counts/sec (15-350 keV), at ~4 sec after the trigger. The XRT began observing the field at 22:51:32.6 UT, 61.9 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 170.7694, -3.5153 which is equivalent to: RA(J2000) = +11h 23m 4.66s Dec(J2000) = -03d 30' 55.1" with an uncertainty of 4.8 arcseconds (radius, 90% containment). This location is 17 arcseconds from the BAT onboard position, within the BAT error circle. Despite the onboard localisation, no X-ray source was detected in 732 s of promptly-downlinked data, suggesting that the initial centroid may equally have been a cosmic ray. This position should therefore be treated with caution. The initial flux in the 2.5 s image was 5.90e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 70 seconds after the BAT trigger. No aspect solution is available for the 2.7'x2.7' sub-image; results from the list of sources generated on-board are not available at this time. The expected extinction corresponding to E(B-V) of 0.05. We note that the XRT position is 1.4 arcminutes from the galaxy 2MASX J11225935-0331287, at redshift 0.1126, which has a nominal radius of 0.3 arcminutes according to NED. Burst Advocate for this burst is V. D'Elia (delia AT asdc.asi.it). 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: 13935 SUBJECT: GRB 121031A: Prompt enhanced Swift-XRT position DATE: 12/10/31 23:39:44 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Using promptly downlinked XRT event data for GRB 121031A, we find an enhanced XRT position of the afterglow: RA, Dec: 170.7705, -3.5172 which is equivalent to: RA (J2000) = 11 23 04.91 Dec (J2000) = -03 31 01.9 with an uncertainty of 2.0 arcseconds (radius, 90% confidence). Analysis of the promptly available data is online at http://www.swift.ac.uk/sper/537195. Position enhancement is is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13936 SUBJECT: GRB 121031A: Swift-BAT refined analysis DATE: 12/11/01 12:43:18 GMT FROM: Scott Barthelmy at NASA/GSFC GRB 121031A: Swift-BAT refined analysis S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), V. D'Elia (ASDC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), 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-61 to T+243 sec from recent telemetry downlinks, we report further analysis of BAT GRB 121031A (trigger #537195) (D'Elia, et al., GCN Circ. 13934). The BAT ground-calculated position is RA, Dec = 170.772, -3.513 deg, which is RA(J2000) = 11h 23m 05.2s Dec(J2000) = -03d 30' 47.7" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. The mask-weighted light curve shows a FRED-like peak with a couple smaller peaks superposed. It starts at ~T-10 sec, peaks at ~T+4 sec, and ends at ~T+100 sec. T90 (15-350 keV) is 62.5 +- 25.1 sec (estimated error including systematics). The time-averaged spectrum from T-2.64 to T+98.31 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.59 +- 0.07. The fluence in the 15-150 keV band is 3.1 +- 0.1 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+4.10 sec in the 15-150 keV band is 2.2 +- 0.2 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/537195/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13944 SUBJECT: GRB 121031A: Enhanced Swift-XRT position DATE: 12/11/02 15:25:05 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 4059 s of XRT Photon Counting mode data and 5 UVOT images for GRB 121031A, 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 = 170.77019, -3.51704 which is equivalent to: RA (J2000): 11h 23m 4.85s Dec (J2000): -03d 31' 01.3" with an uncertainty of 1.4 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: 13946 SUBJECT: GRB 121031A: Swift-XRT refined Analysis DATE: 12/11/02 16:48:38 GMT FROM: Valerio D'Elia at ASDC V. D'Elia (ASDC) reports on behalf of the Swift-XRT team: We have analysed 9.2 ks of XRT data for GRB 121031A (D'Elia et al. GCN Circ. 13934), from 68 s to 22.6 ks after the BAT trigger. The data comprise 276 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Goad et al. (GCN. Circ 13935, 13944). The late-time light curve (from T0+4.7 ks) can be modelled with a power-law decay with a decay index of alpha=0.86 (+/-0.07). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.03 (+/-0.08). The best-fitting absorption column is 4.6 (+0.4, -0.3) x 10^21 cm^-2, in excess of the Galactic value of 4.0 x 10^20 cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a photon index of 2.33 (+/-0.10) and a best-fitting absorption column of 5.2 (+/-0.4) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.9 x 10^-11 (9.1 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 5.2 (+/-0.4) x 10^21 cm^-2 Galactic foreground: 4.0 x 10^20 cm^-2 Excess significance: 18.5 sigma Photon index: 2.33 (+/-0.10) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00537195. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13947 SUBJECT: GRB 121031A: Swift/UVOT Upper Limits DATE: 12/11/02 18:26:47 GMT FROM: Samantha Oates at MSSL S. R. Oates (MSSL-UCL) and V. D'Elia (ASDC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 121031A 70 s after the BAT trigger (D'Elia et al., GCN Circ. 13934). No optical afterglow consistent with the enhanced XRT position (Goad et al., GCN Circ. 13944) 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 70 220 147 >19.9 white 5366 7002 393 >20.5 v 5776 11730 787 >19.4 b 5161 18152 492 >20.0 u 16939 17239 295 >19.5 w1 4751 16932 1279 >20.5 m2 4545 22572 1870 >21.1 w2 5572 11120 1082 >20.8 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.05 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13949 SUBJECT: GRB 121031A, Early peak observed with Swift-BAT DATE: 12/11/03 02:06:03 GMT FROM: Jay R. Cummings at NASA/GSFC/Swift GRB 121031A, Early peak observed with Swift-BAT 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/UMD), D. M. Palmer (LANL), A. M. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team): With an additional data set from T-240 to T-61 sec, we report further analysis of BAT GRB 121031 (trigger #537195) (D'Elia, et al., GCN Circ. 13934). In an earlier circular (Barthelmy, et al., GCN Circ. 13936) we described the second of two equal-sized peaks from this burst. BAT triggered on that second peak. The earlier peak occurred during a pre- planned slew maneuver, and its time interval was not covered by the data available at the time the circular was produced. The entire burst had two large peaks at T-190 and T0 that were about the same in flux, duration, and shape. Each was a FRED about 60 seconds long as seen in BAT. There was a small peak at T-50 sec of about 5 seconds duration. For the entire burst, T90 (15-350 keV) was 226 +- 19 sec (estimated error including systematics). The time-averaged spectrum from T-209.0 to T+98.3 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.50 +- 0.05. The fluence in the 15-150 keV band is 7.8 +- 0.2 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T-190.72 sec in the 15-150 keV band is 2.4 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13951 SUBJECT: GRB 121031A: Fermi GBM detection DATE: 12/11/07 03:29:06 GMT FROM: Adam Goldstein at Fermi-GBM/UAH A. Goldstein (UAH) and C.A. Meegan (USRA) report on behalf of the Fermi GBM Team: "At 22:47:15.27 UT on 31 October 2012, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 121031A (trigger 373416438 / 121031949). which was also detected by the Swift/BAT (V. D'Elia et al. 2012, GCN 13934). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 85 degrees. This burst was also independently detected by INTEGRAL SPI-ACS. The GBM light curve consists of two main pulses separated by a long quiescent period with a total burst duration (T90) of about 242 s (50-300 keV) with a possible soft tail out to about T0+500 s. The time-averaged spectrum from T0=-47 s to T0+297 s is adequately fit by a power law function with an exponential high-energy cutoff. The power law index is -0.87 +/- 0.07 and the cutoff energy, parameterized a as Epeak, is 142.3 +/- 10.8 keV The event fluence (10-1000 keV) in this time interval is (1.99 +/- 0.09)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+4.6 s in the 8-1000 keV band is 7.4 +/- 0.7 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."