//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15440 SUBJECT: GRB 131103A: Swift detection of a burst DATE: 13/11/03 22:19:31 GMT FROM: David Palmer at LANL J. R. Cummings (NASA/UMBC), S. D. Barthelmy (GSFC), D. N. Burrows (PSU), V. D'Elia (ASDC), N. Gehrels (NASA/GSFC), J. A. Kennea (PSU), C. B. Markwardt (NASA/GSFC), F. E. Marshall (NASA/GSFC), C. Pagani (U Leicester), K. L. Page (U Leicester) and D. M. Palmer (LANL) report on behalf of the Swift Team: At 22:07:25 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 131103A (trigger=576562). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 348.954, -44.670 which is RA(J2000) = 23h 15m 49s Dec(J2000) = -44d 40' 11" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of at least 20 sec with possible emission on a longer timescale. The peak count rate was ~2000 counts/sec (15-350 keV), at ~1 sec after the trigger. The XRT began observing the field at 22:08:42.0 UT, 76.3 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 348.92161, -44.63816 which is equivalent to: RA(J2000) = 23h 15m 41.19s Dec(J2000) = -44d 38' 17.4" with an uncertainty of 3.6 arcseconds (radius, 90% containment). This location is 141 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 (1.11 x 10^20 cm^-2, Kalberla et al. 2005), with an excess column of 4 (+2.09/-1.83) x 10^21 cm^-2 (90% confidence). The initial flux in the 2.5 s image was 1.31e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 86 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 typical 3-sigma upper limit has been about 19.6 mag. 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 0.01. Burst Advocate for this burst is J. R. Cummings (jayc 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: 15441 SUBJECT: GRB 131103A: Swift-XRT refined Analysis DATE: 13/11/04 12:20:15 GMT FROM: Phil Evans at U of Leicester D.N. Burrows (PSU), J.A. Kennea (PSU), V. Mangano (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), C. Pagani (U. Leicester), B. Sbarufatti (INAF-OAB/PSU), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC) and J.R. Cummings report on behalf of the Swift-XRT team: We have analysed 9.1 ks of XRT data for GRB 131103A (Cummings et al. GCN Circ. 15440), from 82 s to 25.5 ks after the BAT trigger. The data comprise 793 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The refined XRT position is RA, Dec = 348.9213, -44.6377 which is equivalent to: RA (J2000): 23 15 41.11 Dec(J2000): -44 38 15.7 with an uncertainty of 3.5 arcsec (radius, 90% confidence). The late-time light curve (from T0+5.9 ks) can be modelled with a power-law decay with a decay index of alpha=1.16 (+/-0.26). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.76 (+0.27, -0.25). The best-fitting absorption column is 4.0 (+0.8, -0.7) x 10^21 cm^-2, in excess of the Galactic value of 1.1 x 10^20 cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a photon index of 2.15 (+0.18, -0.17) and a best-fitting absorption column of 3.5 (+0.7, -0.6) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.0 x 10^-11 (7.2 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 3.5 (+0.7, -0.6) x 10^21 cm^-2 Galactic foreground: 1.1 x 10^20 cm^-2 Excess significance: 8.9 sigma Photon index: 2.15 (+0.18, -0.17) If the light curve continues to decay with a power-law decay index of 1.16, the count rate at T+24 hours will be 6.4 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.6 x 10^-13 (4.6 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/00576562. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15442 SUBJECT: GRB 131103A: Enhanced Swift-XRT position DATE: 13/11/04 14:25:13 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 7277 s of XRT Photon Counting mode data and 8 UVOT images for GRB 131103A, 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 = 348.91855, -44.64060 which is equivalent to: RA (J2000): 23h 15m 40.45s Dec (J2000): -44d 38' 26.1" 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: 15443 SUBJECT: GRB 131103A: Swift/UVOT Detection DATE: 13/11/04 15:51:58 GMT FROM: Frank Marshall at GSFC N. P. M. Kuin (UCL-MSSL), F. E. Marshall (NASA/GSFC), and J. R. Cummings (NASA/UMBC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 131103A 87 s after the BAT trigger (Cummings et al., GCN Circ. 15440). A decaying source consistent with the XRT position (Goad et al. GCN Circ. 15442) is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 23:15:40.55 = 348.91894 (deg.) Dec (J2000) = -44:38:25.4 = -44.64040 (deg.) with an estimated uncertainty of 0.60 arc sec. (radius, 90% confidence). Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 87 237 147 19.41 +/- 0.13 white 19290 19893 599 21.45 +/- 0.17 v 629 12543 1173 >20.0 b 554 25509 1664 21.64 +/- 0.23 u 299 549 246 18.93 +/- 0.13 w1 678 24073 1116 >20.6 w2 6741 6941 197 >19.8 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.01 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15445 SUBJECT: GRB 131103A: NOT and VLT observations DATE: 13/11/04 20:14:45 GMT FROM: Steve Schulze at U of Iceland Z. Cano (U Iceland), S. Schulze (PUC, MCSS), D. Malesani (DARK/NBI), P. Jakobsson (U Iceland), D. J. Watson (DARK/NBI), N. R. Tanvir (U Leicester), D. Xu, J. P. U. Fynbo (DARK/NBI) and M. Hayes (Stockholm University) report on behalf of a larger collaboration: We observed the field of GRB 131103A (Cummings et al., GCN Circ. 15440) with the 2.5-m Nordic Optical Telescope (NOT) equipped with ALFOSC, and subsequently with the ESO VLT using the optical acquisition camera of the X-shooter spectrograph, as well as with the HAWK-I near-infrared imager. A brief summary of our observations is reported below. For the NOT observation, the object was very low on the horizon (airmass = 4.56), hence we could only achieve a poor S/N. At the position of the UVOT afterglow (Kuin et al., GCN Circ. 15443), a source is detected in all our images. It is clearly elongated in both R and J as seen in the VLT data, and we thus suggest that this is the host galaxy, though some afterglow contribution cannot be excluded. We note that a marginally significant object is visible in the DSS (R band) at the same position. Instrument Time (hr) Filter Magnitude NOT/ALFOSC 1.29 R 20.07 +/- 0.12 VLT/X-shooter 4.48 R 20.48 +/- 0.01 VLT/HAWK-I 5.94 J 19.63 +/- 0.02 While the comparison of the two R-band magnitudes provides some evidence for fading, we note that both R-band measurements have an uncertain calibration, since no common star is available between the ALFOSC and X-shooter images. The two measurements are therefore tied to different USNO stars, which can introduce an error of ~0.1-0.2 mag. Specifically, we used the R1 magnitudes of stars 0453-0803362 and 0453-0803335 for ALFOSC and X-shooter, respectively. The HAWK-I observation was calibrated against five nearby 2MASS stars. We kindly acknowledge excellent support by the observing staff at the VLT, in particular Claudia Reyes, Dimitri Gadotti, Julien Girard and Roger Wesson. [GCN OPS NOTE(12nov13): Per author's request, the observing time for the VLT/X-shooter was changed from 5.84 to 4.48.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15451 SUBJECT: GRB 131103A: VLT/X-shooter redshift DATE: 13/11/05 10:08:47 GMT FROM: Dong Xu at DARK/NBI D. Xu, D. Malesani (DARK/NBI), S. Schulze (PUC, MCSS), A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), P. Jakobsson, Z. Cano(U Iceland), N. R. Tanvir (U. Leicester), J. P. U. Fynbo, D. Watson (DARK/NBI), P. Goldoni (APC, CEA/Irfu), S. Vergani (CNRS/GEPI), R. Wijers (U Amsterdam) report on behalf of the X-shooter GRB collaboration: We have obtained further observations of the afterglow of GRB 131103A (Cummings et al., GCN Circ. 15440; Cano et al., GCN 15445) using the ESO VLT equipped with the X-shooter spectrograph, covering the wavelength range 3000-20000 AA. The spectrum was secured on Nov. 5.2 with a total exposure time of 4x600 s. We detect a rich emission line spectrum from the underlying host galaxy at a common redshift z = 0.5955. We also detect strong absorption lines from FeII and MgII at the same redshift in the blue part of the spectrum implying that there is significant afterglow light superimposed on the host light. We acknowledge excellent support from the observing staff at Paranal, in particular Dimitri Gadotti, Roger Wesson, and Claudia Reyes. [GCN OPS NOTE(05nov13): Per author's request, the typo in the redshift value was changed from 0.599 to 0.5955.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15457 SUBJECT: GRB 131103A: Swift-BAT refined analysis DATE: 13/11/05 16:40:45 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), 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 131103A (trigger #576562) (Cummings, et al., GCN Circ. 15440). The BAT ground-calculated position is RA, Dec = 348.948, -44.645 deg which is RA(J2000) = 23h 15m 47.5s Dec(J2000) = -44d 38' 42.3" with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 30%. The mask-weighted light curve shows a 2 or 3 overlapping peaks starting at ~T-8 sec, peaking at ~T+0 sec, and ending at ~T+15 sec. T90 (15-350 keV) is 17.3 +- 4.8 sec (estimated error including systematics). The time-averaged spectrum from T-9.5 to T+13.5 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.97 +- 0.19. The fluence in the 15-150 keV band is 8.2 +- 1.0 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+0.62 sec in the 15-150 keV band is 1.5 +- 0.3 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/576562/BA/