//////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 271 SUBJECT: GRB990308, Possible new SGR~0209+70 DATE: 99/03/08 22:07:34 GMT FROM: David Palmer at USRA/GSFC On behalf of the Konus team, David Palmer writes: Konus has detected two series of short spike bursts (typically shorter than the 64 ms sampling time) on 1999 March 7 & 8. One such series begins on 990307 at Seconds of Day (SOD) 62019.5, with subsequent bursts at +12, +20, +57 (double spike), +72, and +87 (positive flux in 4 consecutive 64 ms samples) seconds later. The fine time resolution sampling ends at +100 seconds. The spikes at +20 and +87 seconds each exceed 200 counts per sample. The second series begins at 990308 SOD 11094.5, with a complex burst, with subsequent peaks at +2, +6, +21 and +28 seconds. The initial burst of the second series corresponds to BATSE #7456 (990308_11093), which has a final estimated position of (RA, dec) = (24.8,+67.8) degrees J2000. This is just barely above the horizon as seen by BATSE at that time, and subsequent spikes may have been blocked by Earth occultation. BATSE #7460 (990308_71254) has a final position of (RA,Dec)=(39.8,+71.6) or 6 degrees away from the final BATSE #7456 position. This is consistent with the measurement accuracy, and improbable for two independent bursts on the same day at better than the 95% level, with the usual caveats about post-prior probabilities. The mean location is 8 degrees from the Galactic plane. All of these properties are consistent with a proposed source identification as a previously-unknown SGR. Observations of this sky location with other high-energy instruments are requested. David Palmer palmer@lheamail.gsfc.nasa.gov USA (301) 286-2739 Voice USA (301) 286-1684 Fax //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 272 SUBJECT: GRB990308 (Trig. 7457), optical observations DATE: 99/03/10 11:51:21 GMT FROM: Grant Williams at Clemson G. Williams, H. Park and R. Porrata report on behalf of the LOTIS collaboration: LOTIS and Super-LOTIS obtained early time observations of the error box of GRB 990308 (BATSE Trig. 7457). This event was detected and localized by the XTE/All-Sky Monitor. LOTIS began imaging the area centered on the 'Original' GCN coordinates 12.6 s after the start of the burst. Five images (10 s integration) were obtained at these coordinates before the system received and responded to the 'Final' GCN coordinates. LOTIS began imaging the area centered on the 'Final' GCN coordinates 132.1 s after the start of the burst. The first five LOTIS images covered a small portion of the XTE/ASM error box within, but near the edge of the preliminary BATSE 3-sigma error circle. We matched all stellar objects in the error box with known Guide Star Catalogue objects. No transient sources brighter than m ~ 11.5 (no filter) were detected. Wispy high clouds reduced the system's limiting magnitude during this event. LOTIS slewed to the more accurate 'Final' GCN coordinates 132.1 s after the start of the burst. The subsequent images covered the entire XTE/ASM error box within the BATSE 2-sigma error circle. We found a single anomalous constant source within the error box with a position which corresponds to the position of a V ~ 10.6 asteroid (Laetitia) at the time of the image. All other sources within the XTE/ASM error box correspond to known stars in the GSC. No fading or flaring objects brighter than m ~ 11.0 were found. In addition, Super-LOTIS (60 cm reflector) began a raster scan around the 'LOCBURST' GCN coordinates 1700 s after the start of the burst. Four Super-LOTIS images (30 s integration; t=1694 s, 1809 s, 2620 s, 3923 s) covered most of the XTE/ASM error box within the BATSE 2-sigma error circle. No fading or flaring objects brighter than m ~ 14.0 (no filter) were detected in the Super-LOTIS images. Super-LOTIS is presently operating at a temporary site at LLNL utilizing an uncooled prototype CCD camera. Thin clouds and surrounding building lights prevented the system from reaching a deeper limiting magnitude. Further details of the LOTIS timing and coverage as well as images are posted at: http://hubcap.clemson.edu/~ggwilli/LOTIS/GRB990308.html This message is citable. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 273 SUBJECT: GRB 990308a and GRB 990308b DATE: 99/03/10 16:17:22 GMT FROM: R. Marc Kippen at BATSE/UAH/MSFC Peter Woods, Marc Kippen, Georgia Richardson (UAH/MSFC), and Chryssa Kouveliotou (USRA/MSFC) report on behalf of the BATSE team : We have classified the two bursts mentioned in GCN 271 (BATSE triggers 7456 and 7460) as classical GRBs. The first is a single pulse lasting ~ 0.5 sec with substructure and a very hard spectrum (photon index ~ -1). The second event is much softer (photon index ~ -2) and longer (~ 25 sec). Although these bursts are positionally consistent with one another (within 1 sigma), neither shows characteristics consistent with any of the other known SGRs. Their properties indicate they are classical GRBs. We have searched the DISCLA data for burst emission (1.024 sec time resolution) at the Konus event times reported in GCN 271. The locations of triggers 7456 and 7460 are not occulted at the times given for 990307, but no bursts are detected. For 990308a, we detect the trigger (7456) and a phosphorescence spike at T+45 sec. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 274 SUBJECT: GRB990308 not a new SGR DATE: 99/03/10 17:48:16 GMT FROM: David Palmer at USRA/GSFC David Palmer, on behalf of the Konus team, writes: More complete data from Konus suggests that the spikes in GRB light curves on 990307 and 990308 reported in GCN #271 are instrumental in origin. In addition, the pulses were absent in data from other spacecraft, including Ulysses (K. Hurley, priv. comm.), RXTE (F. Marshall, priv. comm.) and BATSE (Woods et al. GCN 273). We therefore retract our suggestion that these observations are of a new Soft Gamma Repeater. David Palmer palmer@lheamail.gsfc.nasa.gov USA (301) 286-2739 Voice USA (301) 286-1684 Fax //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 275 SUBJECT: ASM/IPN error box for GRB 990308 (BATSE #7457) DATE: 99/03/14 19:43:32 GMT FROM: Don Smith at MIT D. A. Smith, A. Levine, and R. Remillard (MIT), on behalf of the RXTE/ASM team at MIT and NASA/GSFC, K. Hurley (UCB), on behalf of the Ulysses GRB team, and S. Barthelmy (NASA/GSFC) report: GRB 990308 was detected by the All-Sky Monitor on RXTE during a 90-s observation that began at MJD 51245.218333 (03/08/99 05:14:24 UTC). This burst was also observed by BATSE (Trigger #7457), and the BATSE trigger time was 05:15:07 UTC. At this time, SSC 3 of the ASM (the camera aligned with the rotation axis of the ASM assembly) observed an interval of enhanced count rates that lasted until the end of the observation. The light curve of the event was highly variable, with a mean 1.5-12 keV flux of about 400 mCrab. SSC 3 has lost the use of four of its eight resistive anodes over its the three years of operation, but we could still localize this GRB with the remaining anodes to a 10 deg by 6.6 arcmin error box (full-width at 90% confidence, including estimates of both statistical and systematic effects), centered at R.A. = 182.761832, Decl. = +4.282319 (J2000) and rotated 51.2 deg east from north. GRB 990308 was also detected, very weakly, by Ulysses, and it was therefore possible to obtain an IPN annulus by triangulation of burst arrival times at Ulysses and BATSE. This annulus is centered at R.A. = 154.0761 degrees, Decl. = -9.6383 degrees, with a radius of 35.583 degrees, and a 3 sigma half-width of 0.399 degrees. This annulus is based on preliminary data, but we do not expect it to improve much, if at all. The IPN annulus and the ASM error box cross each other, yielding a joint error box 48 arcmin by 6.6 arcmin. The corners of this box lie within the BATSE LOCBURST error circle, and their celestial coordinates are: R.A.(J2000) Decl. (J2000) 186.142867 +6.921870 186.091377 +7.021754 185.502582 +6.412172 185.451355 +6.512323 This position was still in the FOV of SSC 3 after its 6-deg rotation, and examination of the instrument response at the center of the joint error box yields a ~4-sigma detection of a ~50 mCrab flux (1.5-12 keV), averaged over the next 90-s ASM observation (56-146 s after the burst trigger). This is an average of less than 2 c/s in the time-series data during this observation, which shows an average total count rate of 27 c/s, so it is not possible to directly measure the burst behavior on any shorter time-scales. By the second observation after the burst (t=152-242 s), the average flux had fallen below 30 mCrab (3-sigma upper limit). Figures showing localizations of GRB 990308, as well as the time- series data from the first ASM observation, can be seen on the WWW at http://xte.mit.edu/grb/trig7457.24/web_trig7457_24.html This report may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 726 SUBJECT: GRB990308, HST/STIS observations of the host galaxy DATE: 00/06/21 12:10:06 GMT FROM: Stephen Holland at IFA, U of Aarhus Stephen Holland, Johan Fynbo, Bjarne Thomsen (University of Aarhus), Michael Andersen (University of Oulu), Gunnlaugur Bjornsson (University of Iceland), Jens Hjorth (University of Copenhagen), Andreas Jaunsen (University of Oslo), Priya Natarajan (University of Cambridge, & Yale), and Nial Tanvir (University of Hertfordshire) We have obtained 7842 seconds of STIS images with the 50CCD (clear) aperture of the sky where the optical afterglow associated with GRB 990308 was detected. This data was taken as part of the Survey of the Host Galaxies of Gamma-Ray Bursts (Holland et al. GCN 698) approximately 468 days after the burst occurred. Combined images are now available at "http://www.ifa.au.dk/~hst/grb_hosts/data/index.html". We estimate that the uncertainty in the location of the optical afterglow in our drizzled STIS image is approximately 1.2 arcsec, mostly due to the uncertainty in transferring the Schaefer et al. (1999, ApJL, 524, L103) coordinates for the afterglow to the STIS image. We do not detect any objects within this error circle, and estimate that our five-sigma limiting magnitude is V ~ 28.5. There are two faint, extended sources located 1.448 arcseconds (1.2 sigma) and 2.228 arcseconds (1.9 sigma) west of Schaefer et al. (1999)'s position for the optical afterglow. Some properties of these objects are given below. Object X Y magnitude FWHM(") Ellipticity 1 1081.77 909.91 26.9 +/- 0.1 0.10 0.09 2 1086.91 879.21 27.0 +/- 0.1 0.11 0.36 The X and Y values are the pixel coordinates on our drizzled image and the magnitude is the STIS 50CCD (clear) AB magnitude measured in an aperture with a diameter of 0.75 arcsec. The resolution limit of the image is ~0.084 arcseconds. There are no other objects within approximately six arcseconds of the Schaefer et al. (1999) position for the optical afterglow, so it is possible that one of these objects is the host galaxy for GRB 990308. A GIF image of the error circle, and the two extended objects, is available at "http://www.ifa.au.dk/~hst/grb_hosts/data/grb990308cd.gif".