//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8595 SUBJECT: GRB 081203: Swift detection of a burst with a bright optical counterpart DATE: 08/12/03 14:09:33 GMT FROM: Scott Barthelmy at NASA/GSFC A. M. Parsons (GSFC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU), P.A. Curran (MSSL-UCL), P. A. Evans (U Leicester), O. Godet (U Leicester), C. Gronwall (PSU), S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU), V. La Parola (INAF-IASFPA), V. Mangano (INAF-IASFPA), J. Mao (INAF-OAB), R. Margutti (Univ Bicocca&OAB), F. E. Marshall (NASA/GSFC), P. T. O'Brien (U Leicester), J. P. Osborne (U Leicester), C. Pagani (PSU), K. L. Page (U Leicester), B. Preger (ASDC), P. Romano (INAF-IASFPA), B. Sbarufatti (INAF-IASFPA), R. L. C. Starling (U Leicester), E. Troja (INAF-IASFPA), T. N. Ukwatta (GSFC/GWU) and L. Vetere (PSU) report on behalf of the Swift Team: At 13:57:11 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 081203 (trigger=336489). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 233.033, +63.498 which is RA(J2000) = 15h 32m 08s Dec(J2000) = +63d 29' 54" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a two peak structure with a duration of about 70 sec. The peak count rate was ~4000 counts/sec (15-350 keV), at ~32 sec after the trigger. The XRT began observing the field at 13:58:34.7 UT, 83.1 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 233.0316, +63.5207 which is equivalent to: RA(J2000) = 15h 32m 07.58s Dec(J2000) = +63d 31' 14.5" with an uncertainty of 5.9 arcseconds (radius, 90% containment). This location is 81 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy. UVOT took a finding chart exposure of 150 seconds with the White filter starting 92 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 15:32:07.58 = 233.03158 DEC(J2000) = +63:31:14.9 = 63.52081 with a 90%-confidence error radius of about 0.74 arc sec. This position is 0.4 arc sec. from the center of the XRT error circle. The estimated magnitude is 14.55 with a 1-sigma error of about 0.14. No correction has been made for the expected extinction corresponding to E(B-V) of 0.02. Burst Advocate for this burst is A. M. Parsons (parsons 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: 8596 SUBJECT: GRB081203: optical observation DATE: 08/12/03 15:01:11 GMT FROM: Alexei Pozanenko at IKI, Moscow M. Andreev, A. Sergeev, (Terskol Branch of Institute of Astronomy), Ju. Babina (CrAO) A. Pozanenko (IKI) on behalf of larger GRB follow up collaboration report: We observed the field of GRB 081203 detected by SWIFT ( with the Z-600 telescope of Mt. Terskol observatory. A few first unfiltered images confirm the presence bright afterglow detected by UVOT Parsons et al, GCN Parsons) in coordinates (J2000) 15 32 07.75 +63 31 15.04. A preliminary photometry at Dec.03 (UT) 14:29:30 against USNO-A2.0 (R) is 14.9 mag. Observation is continuing. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8598 SUBJECT: GRB 081203: Enhanced Swift-XRT position DATE: 08/12/03 18:31:36 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 2654 s of XRT Photon Counting mode data and 4 UVOT images for GRB 081203, 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 = 233.0327, +63.5207 which is equivalent to: RA (J2000): 15h 32m 7.84s Dec (J2000): +63d 31' 14.4" with an uncertainty of 1.7 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 http://www.swift.ac.uk/xrt_positions/Goad.pdf), the current algorithm is an extension of this method. This circular was automatically generated, and is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8603 SUBJECT: Swift UVOT observations of GRB 081203 DATE: 08/12/03 22:06:27 GMT FROM: Massimiliano de Pasquale at MSSL-UCL M. De Pasquale (MSSL/UCL) and A. Parsons (GSFC) reports, on the behalf of the Swift UVOT team: Swift UVOT began settled exposures of GRB081203 (trigger 336489, Parsons et al, GCN circular 8595) 93 s after the burst trigger. A bright optical transient is detected at the following coordinates: RA = 15h 32m 07.58s (=233.031580), Dec = +63d 31m 14.9s (=63.520810) J2000 with an uncertainty of 0.5'' (90% confidence level). This position is consistent with the XRT refined error circle (Goad et al, GCN circ 8598). The source is detected in all filters but um2. Below, we show time of observations, the exposure time and the magnitude and 3 sigma upper limits for this optical afterglow. T_start (s) T_stop (s) Exp (s) Mag wh 93 242 146.2 14.53 +/- 0.01 wh 586 605 19.5 13.91 +/- 0.01 v 636 655 19.5 13.30 +/- 0.03 b 561 580 19.5 13.53 +/- 0.01 u 306 555 246 13.07 +/- 0.01 u 709 728 19.5 13.53 +/- 0.02 uw1 685 704 19.5 14.82 +/- 0.07 um2 660 679 19.5 > 17.57 um2 660 6008 412.6 > 20.1 uw2 611 630 19.5 17.19 +/- 0.25 The nondetection in the um2 filter is consistent with the redshift z=2.1 derived from grism spectra (Landsman et al, GCN circ 8601). The detection in the uw2 filter is consistent with this redshift due to the long-wavelength tail of the uw2 filter response. The above magnitudes have not bee corrected for the Galactic extinction corresponding to E(B-V) = 0.02 (Schlegel et al 1998) The photometry is on the UVOT flight system described in Poole et al (2008, MNRAS, 383,627)