//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8051 SUBJECT: GRB 080802: Swift detection of a probable burst DATE: 08/08/02 15:46:43 GMT FROM: David Palmer at LANL W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester), M. M. Chester (PSU), C. B. Markwardt (CRESST/GSFC/UMD), D. M. Palmer (LANL) and E. Troja (INAF-IASFPA) report on behalf of the Swift Team: At 15:12:21 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 080802 (trigger=318832). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 270.748, -32.333 which is RA(J2000) = 18h 02m 60s Dec(J2000) = -32d 19' 59" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 50 sec. The peak count rate was ~1000 counts/sec (15-350 keV), at ~2 sec after the trigger. The XRT began observing the field at 15:13:39.7 UT, 78 seconds after the BAT trigger. Using promptly downlinked data we find a bright, variable, uncatalogued X-ray source located at RA, Dec 270.72692, -32.33395 which is equivalent to: RA(J2000) = 18h 02m 54.46s Dec(J2000) = -32d 20' 02.2" with an uncertainty of 3.1 arcseconds (radius, 90% containment). This is 1.1 arcminutes from the BAT position and within its error radius. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (2.75e+21 cm^-2, Kalberla et al. 2005), with an excess column of 2.3 (+2.63/-2.21) x 10^21 cm^-2 (90% confidence). The initial flux in the 2.5 s image was 1.47e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm) filter starting 86 seconds after the BAT trigger. No afterglow candidate is apparent in the initial data products. The 2.7'x2.7' sub-image covers 25% of the BAT error circle and 100% of the XRT error circle. The typical 3-sigma upper limit has been about 18.5 mag. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction, which at this location is large and uncertain. Because this source is near the Galactic center, this event may be a local transient rather than a cosmological GRB. However, no known sources are found at the XRT position in either SIMBAD or NED. No BAT_POSITION notice was available due to a TDRSS hand-over at the time of the burst. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8052 SUBJECT: GRB 080802, Swift-BAT refined analysis DATE: 08/08/03 00:12:25 GMT FROM: Scott Barthelmy at NASA/GSFC H. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), W. Baumgartner (GSFC/UMBC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), C. Markwardt (GSFC/UMD), K. McLean (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+388 sec from the recent telemetry downlink, we report further analysis of BAT GRB 080802 (trigger #318832) (Baumgartner, et al., GCN Circ. 8051). The BAT ground-calculated position is RA, Dec = 270.729, -32.329 deg which is RA(J2000) = 18h 02m 55.0s Dec(J2000) = -32d 19' 45.6" with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. The mask-weighted light curve shows several overlapping peaks starting at ~T-40 sec and ending at ~T+180. T90 (15-350 keV) is 176 +- 50 sec (estimated error including systematics). The time-averaged spectrum from T-31.1 to T+176.9 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.76 +- 0.19. The fluence in the 15-150 keV band is 1.3 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T-7.56 sec in the 15-150 keV band is 0.3 +- 0.0 ph/cm2/sec. All the quoted errors are at the 90% confidence level. Given the Galactic lon,lat being in the bulge, we can not rule out a non-GRB source for this trigger. All other factors point to a GRB. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/318832/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8053 SUBJECT: GRB 080802: UVI Telescope Upper Limit DATE: 08/08/03 01:17:11 GMT FROM: Adria C. Updike at Clemson U Adria C. Updike (Clemson U), James Neff (College of Charleston), and Dieter H. Hartmann (Clemson U) report: We observed the field of GRB 080802 (GCN 8051, Baumgartner et al.) using the 0.5m UVI (University of the Virgin Islands) telescope at St. Thomas for 5 minutes in the R band, beginning 00:12 UT (~9 hours after the trigger). We detect no new sources within the XRT error circle to a limiting magnitude of R ~ 18.5 as calibrated against the USNO B1.0 catalog. Further observations we hampered by cloud cover. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8054 SUBJECT: GRB 080802: Swift-XRT Refined Analysis DATE: 08/08/03 03:20:34 GMT FROM: Michael Stroh at PSU/Swift M.C. Stroh (PSU) reports on behalf of the Swift-XRT team: We have analyzed the first two orbits of Swift-XRT data obtained for GRB 080802 (Baumgartner et al., GCN Circ. 8051), totaling 81s of Windowed Timing and 2.4ks of Photon Counting data. The X-ray light-curve begins with a single flare that peaks to ~40 cts/ s near T+100 seconds. The rest of the light-curve can be fit by a single broken power-law with an initial decay index of 2.91 +/- 0.33, second decay index of -0.51 +/- 0.25 and a break near T+1000s. Since the second decay index indicates brightening, we cannot accurately predict counting rates at T+24 or T+48 hours. The spectrum from the Windowed Timing data can be fit with a power-law in excess of the Galactic value (2.75e21 cm-2, Kalberla et al. 2005), with a column density of 4.8 (+2.0/-1.7)e21 cm^-2 and a photon index of 1.40 (+0.24/-0.22). The observed (unabsorbed) 0.3-10 keV flux is 4.78e-10 (4.95e-10) ergs/cm^2/s. This is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8055 SUBJECT: GRB 080802: Swift/UVOT Upper Limits DATE: 08/08/03 05:56:21 GMT FROM: Patricia Schady at MSSL/Swift P. Schady (MSSL-UCL) and W.H. Baumgartner (GSFC/UMBC) report on behalf of the Swift/UVOT team: The Swift/UVOT observed the field of GRB 080802 starting 87 s after the BAT trigger (Baumgartner et al., GCN Circ. 8051). We do not find a source in any of the UVOT observations inside the XRT error circle (Baumgartner et al., GCN Circ. 8051). The 3-sigma upper limits for detecting a source in the first white and v finding charts (FC) exposure and co-added frames are: Filter T_start T_stop Exp Mag (3-sigma UL) (s) (s) (s) ========================================================= white (FC) 87 186 100 > 20.0 white 4803 5002 200 > 20.4 v (FC) 193 406 213 > 18.7 v 5214 5413 200 > 18.7 b 4598 6189 356 > 20.1 u 4393 6028 400 > 19.9 uvw1 4188 5822 400 > 19.8 uvm2 3983 5618 400 > 19.7 uvw2 5009 5208 200 > 19.5 The values quoted above are not corrected for the expected Galactic extinction corresponding to a reddening of E(B-V) = 0.80 mag in the direction of the burst (Schlegel et al. 1998).