//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11203 SUBJECT: GRB 100904A: Swift detection of a burst DATE: 10/09/04 01:42:08 GMT FROM: David Palmer at LANL T. N. Ukwatta (GSFC/GWU), W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU), J. R. Cummings (NASA/UMBC), P. A. Evans (U Leicester), J. M. Gelbord (PSU), S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL), K. L. Page (U Leicester), D. M. Palmer (LANL), A. Rowlinson (U Leicester), M. H. Siegel (PSU) and C. A. Swenson (PSU) report on behalf of the Swift Team: At 01:33:43 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 100904A (trigger=433273). Due to the Sun constraint, Swift could not slew to the burst. The BAT on-board calculated location is RA, Dec 172.919, -16.209 which is RA(J2000) = 11h 31m 41s Dec(J2000) = -16d 12' 31" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a double-peaked structure with a duration of about 30 sec. The peak count rate was ~1300 counts/sec (15-350 keV), during the second peak at ~2 sec after the trigger. Due to the proximity of the burst to the Sun, Swift cannot slew to the BAT position. The burst does not become observable by Swift until November 7th; there will thus be no XRT or UVOT data for this trigger. Burst Advocate for this burst is T. N. Ukwatta (tilan.ukwatta AT gmail.com). 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: 11207 SUBJECT: GRB 100904A: Swift-BAT refined analysis DATE: 10/09/04 13:50:20 GMT FROM: Tilan Ukwatta at GSFC/GWU T. N. Ukwatta (GWU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (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 (OSU), J. Tueller (GSFC), (i.e. the Swift-BAT team): Using the data set from T-61 to T+242 sec from the recent telemetry downlink, we report further analysis of BAT GRB 100904A (trigger #433273) (Ukwatta, et al., GCN Circ. 11203). The BAT ground-calculated position is RA, Dec = 172.907, -16.185 deg which is RA(J2000) = 11h 31m 37.6s Dec(J2000) = -16d 11' 05.5" with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 30%. The mask-weighted light curve shows two overlapping peaks. The first starts around T-18 sec and peaks around T-13 sec. The second peaks around T+3 sec. T90 (15-350 keV) is 31.3 +/- 7.9 sec (estimated error including systematics). The time-averaged spectrum from T-14.5 to T+23.0 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.67 +/- 0.16. The fluence in the 15-150 keV band is 1.3 +/- 0.1 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+2.29 sec in the 15-150 keV band is 1.6 +/- 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/433273/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11217 SUBJECT: GRB100904A: BOOTES-3 Upper Limit DATE: 10/09/05 20:06:20 GMT FROM: Juan Carlos Tello at IAA-CSIC J.C. Tello, J. Gorosabel, A.J. Castro-Tirado (IAA-CSIC, Granada) P. Kubanek (IAA-CSIC and IPL-UV) W. Allen (Vintage Lane Obs.), Ph. Yock and Kuan-Yu Lin (Auckland Univ.), report on behalf of a larger collaboration: "We have carried out observations of the Swift GRB 100904A (Ukwatta et al. GCNC 11203) on Sep 4.2982 - 4.3145 UT (~5.98 hr after the onset of the burst, mean observing time) with the 0.6m Yock-Allen robotic telescope (BOOTES-3) located in Blenheim, New Zealand. Observations were carried out at high airmass (~ 7). We do not detect any optical source within the Swift-BAT refined analysis error circle (Ukwatta et al. GCNC 11207). The 3 sigma limiting magnitude of the co-added unfiltered image (Texp=16x60s) is R ~ 18.0, using USNO-B1.0 as photometric reference." [GCN OPS NOTE(06sep10): Per author's request, K-YL was added to the author list.]