//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13938 SUBJECT: GRB 121102A: Swift detection of a burst DATE: 12/11/02 02:46:30 GMT FROM: Scott Barthelmy at NASA/GSFC V. D'Elia (ASDC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU), J. R. Cummings (NASA/UMBC), N. Gehrels (NASA/GSFC), J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB/PSU) and M. H. Siegel (PSU) report on behalf of the Swift Team: At 02:27:02 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 121102A (trigger=537266). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 270.903, -16.966 which is RA(J2000) = 18h 03m 37s Dec(J2000) = -16d 57' 56" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a single FRED-like peak with a duration of about 25 sec. The peak count rate was ~3500 counts/sec (15-350 keV), at ~6 sec after the trigger. The XRT began observing the field at 02:27:50.4 UT, 47.7 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source with an enhanced position: RA, Dec 270.9009, -16.9578 which is equivalent to: RA(J2000) = 18h 03m 36.22s Dec(J2000) = -16d 57' 28.2" with an uncertainty of 2.1 arcseconds (radius, 90% containment). This location is 30 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 (5.33 x 10^21 cm^-2, Kalberla et al. 2005), with an excess column of 3.1 (+3.61/-1.55) x 10^21 cm^-2 (90% confidence). The initial flux in the 2.5 s image was 3.45e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 57 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 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. Because of the density of catalogued stars, further analysis is required to report an upper limit for any afterglow in the region. No correction has been made for the large, but uncertain extinction expected. This event has all appearances of a GRB: hard BAT spectrum, bright XRT initial detection and fading. Still, we note that the galactic coordinates are l=12 deg, b=2.5 deg, consistent with a galactic origin. We believe it is a GRB, but can not rule out a new galactic transient. 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: 13939 SUBJECT: GRB 121102A : a long GRB detected by INTEGRAL DATE: 12/11/02 03:47:34 GMT FROM: Sandro Mereghetti at IASF/CNR S.Mereghetti (IASF-Milano), D.Gotz (CEA, Saclay), E.Bozzo, C.Ferrigno, R.Boissay (ISDC, Versoix), and J.Borkowski (CAMK, Torun) on behalf of the IBAS Localization Team report: a gamma ray burst lasting about 20 s has been detected by IBAS in the IBIS/ISGRI data at 02:27:00 UT of November 2 The refined coordinates are RA = 270.9034 deg BDEC = -16.9509 deg with an uncertainty of 2 arcmin (90% c.l.). A preliminary analysis gives a burst peak flux of about 1 counts/cm2/s (20-200 keV, 1-s integration time) and a fluence in the same energy range of about 1e-6 erg/cm2. A plot of the light curve will posted at http://ibas.iasf-milano.inaf.it/IBAS_Results.html //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13942 SUBJECT: GRB 121102A: Swift-BAT refined analysis DATE: 12/11/02 12:13:27 GMT FROM: Scott Barthelmy at NASA/GSFC W. H. Baumgartner (GSFC/UMBC), S. D. Barthelmy (GSFC), 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 the recent telemetry downlink, we report further analysis of BAT GRB 121102A (trigger #537266) (D'Elia, et al., GCN Circ. 13938). The BAT ground-calculated position is RA, Dec = 270.896, -16.951 deg, which is RA(J2000) = 18h 03m 35.1s Dec(J2000) = -16d 57' 03.4" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. The mask-weighted light curve shows a FED peak starting at ~T-0.2 sec, peaking at ~T+6 sec, and ending at ~T+95 sec. T90 (15-350 keV) is 24.7 +- 3.4 sec (estimated error including systematics). The time-averaged spectrum from T-0.30 to T+35.25 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.88 +- 0.07. The fluence in the 15-150 keV band is 1.9 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+5.68 sec in the 15-150 keV band is 2.3 +- 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/537266/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13943 SUBJECT: GRB 121102A: Swift-XRT refined Analysis DATE: 12/11/02 14:46:05 GMT FROM: Phil Evans at U of Leicester C. Pagani (U. Leicester), V. Mangano (INAF-IASFPA), A. Melandri (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), J.A. Kennea (PSU), M.C. Stroh (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester) and V. D'Elia report on behalf of the Swift-XRT team: We have analysed 9.0 ks of XRT data for GRB 121102A (D'Elia et al. GCN Circ. 13938), from 53 s to 18.8 ks after the BAT trigger. The data comprise 203 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The best available XRT position (using the promptly downlinked event data, the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue) is RA, Dec = 270.9009, -16.9576 which is equivalent to: RA (J2000): 18 03 36.22 Dec(J2000): -16 57 27.5 with an uncertainty of 2.0 arcsec (radius, 90% confidence). The light curve can be modelled with a series of power-law decays. The initial decay index is alpha=3.33 (+0.22, -0.24). At T+111 s the decay flattens to an alpha of 1.59 (+0.18, -0.11) before breaking again at T+696 s to a final decay with index alpha=1.04 (+0.08, -0.07). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.95 (+/-0.13). The best-fitting absorption column is 8.9 (+/-1.0) x 10^21 cm^-2, in excess of the Galactic value of 5.3 x 10^21 cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a photon index of 1.74 (+0.23, -0.22) and a best-fitting absorption column of 7.7 (+1.9, -1.6) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 5.9 x 10^-11 (9.6 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 7.7 (+1.9, -1.6) x 10^21 cm^-2 Galactic foreground: 5.3 x 10^21 cm^-2 Excess significance: 2.4 sigma Photon index: 1.74 (+0.23, -0.22) If the light curve continues to decay with a power-law decay index of 1.04, the count rate at T+24 hours will be 2.8 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.7 x 10^-13 (2.7 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/00537266. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13945 SUBJECT: GRB 121102A: Enhanced Swift-XRT position DATE: 12/11/02 15:36:39 GMT FROM: Phil Evans at U of Leicester J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team. Using 6668 s of XRT Photon Counting mode data and 8 UVOT images for GRB 121102A, 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 = 270.90101, -16.95788 which is equivalent to: RA (J2000): 18h 03m 36.24s Dec (J2000): -16d 57' 28.4" 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: 13948 SUBJECT: GRB 121102A: Swift/UVOT Upper Limits DATE: 12/11/02 18:48:01 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 121102A 58 s after the BAT trigger (D'Elia et al., GCN Circ. 13938). No optical afterglow consistent with the XRT position (Osborne et al. GCN Circ. 13945) 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 58 207 147 >20.1 u_FC 270 519 246 >19.6 white 58 24618 2113 >21.4 v 4994 17253 1278 >20.0 b 5814 23858 2022 >21.4 u 270 22945 1524 >20.9 w1 5404 18848 1066 >20.8 m2 5200 18158 1279 >21.1 w2 4789 13077 1073 >21.2 The magnitudes in the table are not corrected for the high Galactic extinction due to the reddening of E(B-V) = 1.48 in the direction of the burst (Schlegel et al. 1998).