//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 23493 SUBJECT: GRB 181203A: Swift detection of a burst DATE: 18/12/03 12:23:43 GMT FROM: David Palmer at LANL E. Troja (NASA/GSFC/UMCP), A. P. Beardmore (U Leicester), A. A. Breeveld (UCL-MSSL), J.D. Gropp (PSU), J. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC), M. J. Moss (George Washington University), K. L. Page (U Leicester), D. M. Palmer (LANL) and A. Tohuvavohu (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 12:08:47 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 181203A (trigger=874475). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 108.369, -39.769 which is RA(J2000) = 07h 13m 29s Dec(J2000) = -39d 46' 07" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single-peaked structure with a duration of about 20 sec. The peak count rate was ~1000 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 12:10:01.1 UT, 73.3 seconds after the BAT trigger. The position determined from promptly downlinked data differs significantly from the on-board position, suggesting that the XRT may have centroided on a cosmic ray; the initial XRT position notice should be treated with caution. Using promptly downlinked data we find a fading, uncatalogued X-ray source with an enhanced position: RA, Dec 108.3491, -39.8016 which is equivalent to: RA(J2000) = 07h 13m 23.78s Dec(J2000) = -39d 48' 05.6" with an uncertainty of 2.4 arcseconds (radius, 90% containment). This location is 129 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 consistent with the Galactic value of 2.26 x 10^21 cm^-2 (Willingale et al. 2013). UVOT took a finding chart exposure of 150 seconds with the White filter starting 79 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 0.24. Burst Advocate for this burst is E. Troja (eleonora.troja AT 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: 23494 SUBJECT: GRB 181203A: Enhanced Swift-XRT position DATE: 18/12/03 14:27:43 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 867 s of XRT Photon Counting mode data and 1 UVOT images for GRB 181203A, 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 = 108.34857, -39.80187 which is equivalent to: RA (J2000): 07h 13m 23.66s Dec (J2000): -39d 48' 06.7" with an uncertainty of 2.0 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: 23500 SUBJECT: GRB 181203A: Swift-BAT refined analysis DATE: 18/12/04 03:52:49 GMT FROM: Amy Lien at GSFC S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), E. Troja (NASA/GSFC/UMCP), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 181203A (trigger #874475) (Troja et al., GCN Circ. 23493). The BAT ground-calculated position is RA, Dec = 108.341, -39.783 deg which is RA(J2000) = 07h 13m 21.8s Dec(J2000) = -39d 46' 57.1" with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment). The partial coding was 83%. The mask-weighted light curve shows a single-peaked structure that starts at ~T-2 s, peaks at ~T+1 s, and ends at ~T+16 s. T90 (15-350 keV) is 15.30 +- 1.75 sec (estimated error including systematics). The time-averaged spectrum from T-1.96 to T+15.77 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.79 +- 0.15. The fluence in the 15-150 keV band is 7.8 +- 0.7 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+1.02 sec in the 15-150 keV band is 1.1 +- 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/874475/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 23502 SUBJECT: GRB 181203A: Swift-XRT refined Analysis DATE: 18/12/04 08:46:35 GMT FROM: Phil Evans at U of Leicester A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), A. Tohuvavohu (PSU), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester) and E. Troja report on behalf of the Swift-XRT team: We have analysed 6.2 ks of XRT data for GRB 181203A (Troja et al. GCN Circ. 23493), from 60 s to 64.1 ks after the BAT trigger. The data comprise 9 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 Goad et al. (GCN Circ. 23494). The light curve can be modelled with a power-law decay with a decay index of alpha=2.74 (+0.27, -0.26). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.84 (+0.29, -0.17). The best-fitting absorption column is consistent with the Galactic value of 2.3 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.9 x 10^-11 (5.1 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.3 (+/-0.8) x 10^21 cm^-2 Galactic foreground: 2.3 x 10^21 cm^-2 Excess significance: <1.6 sigma Photon index: 1.84 (+0.29, -0.17) If the light curve continues to decay with a power-law decay index of 2.74, the count rate at T+24 hours will be 3.2 x 10^-8 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.2 x 10^-18 (1.6 x 10^-18) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00874475. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 23505 SUBJECT: GRB 181203A: Swift/UVOT Upper Limits DATE: 18/12/04 16:55:56 GMT FROM: Frank Marshall at Swift/UVOT F. E. Marshall (NASA/GSFC) and E. Troja (NASA/GSFC/UMCP) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 181203A 79 s after the BAT trigger (Troja et al., GCN Circ. 23493). No optical afterglow consistent with the XRT position (Goad et al. GCN Circ. 23494) 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) exposures and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 79 229 147 >20.7 u_FC 293 543 246 >19.4 white 79 1370 373 >21.8 v 624 1421 97 >18.6 b 549 1346 78 >20.0 u 293 1495 324 >19.7 w1 673 1470 97 >19.0 m2 648 1445 97 >18.5 w2 599 1396 97 >19.7 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.24 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 23513 SUBJECT: GRB 181203A: BOOTES-3/YA optical observations DATE: 18/12/05 11:47:59 GMT FROM: Youdong HU at IAA-CSIC, UGR Y.-D. Hu, E. Fernandez-Garcia, A. Ayala and A. J. Castro-Tirado (IAA-CSIC), I. Carrasco and C. Perez del Pulgar (Univ. de Malaga), M. D. Caballero-Garcia (ASU-CAS, CZ) and R. Querel (NIWA), on behalf of a larger collaboration, report: The 60cm BOOTES-3/YA robotic telescope at NIWA Lauder in Otago (New Zealand) automatically responded to the Swift trigger of GRB 181203A (Troja et al. GCNC 23493) ~0.51 h after the burst. At the position of the Swift/XRT enhanced X-ray position (Goad et al. GCNC 23494), no optical afterglow is detected down to 20.4 mag on a 360s co-added unfiltered image at 0.62 h (middle exposure) after trigger, in agreement with the non-detection by Swift/UVOT (Marshall et al. GCNC 23505). We thank the staff at NIWA for its excellent support. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 23516 SUBJECT: GRB 181203A: GROND detection of the afterglow DATE: 18/12/07 06:57:50 GMT FROM: Jan Bolmer at MPE/Garching P. Schady (Univ. of Bath) and J. Bolmer (MPE, Garching) report: We observed the field of GRB 181203A (Swift trigger 874475; Troja et al., GCN #23493) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla Observatory (Chile). Observations started at 02:02 UT on 4th December, 13.4 hours after the GRB trigger. They were performed at an average seeing of 1.6" and at an average airmass of 1.4. We found a faint source within the 2.0 arcsec Swift-XRT error circle reported by Goad et al. (GCN #23494) at RA (J2000.0) = 07:13:23.705 DEC (J2000.0) = -39:48:05.29 with an uncertainty of 0.12" in each coordinate. The source is detected in all filters apart from the z' band, and has a preliminary r'-band AB magnitude of r' = 23.5 +/- 0.1 mag The above magnitude is calibrated against GROND zeropoints and is not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.21 in the direction of the burst (Schlafly & Finkbeiner 2011). We thank Angela Hempel for the excellent support from La Silla.