//////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5575 SUBJECT: GRB 060919: Swift detection of a burst DATE: 06/09/19 08:18:59 GMT FROM: David Palmer at LANL C. Guidorzi (Univ Bicocca&INAF-OAB), S. D. Barthelmy (GSFC), P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), C. Gronwall (PSU), J. A. Kennea (PSU), H. A. Krimm (GSFC/USRA), V. Mangano (INAF-IASFPA), A. Moretti (INAF-OAB), K. L. Page (U Leicester), D. M. Palmer (LANL), P. Romano (INAF-OAB) and S. D. Vergani (DIAS-DCU) report on behalf of the Swift Team: At 07:48:38 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 060919 (trigger=230115). Swift slewed immediately to the burst. The BAT on-board calculated location is RA,Dec 276.911, -51.028 {18h 27m 39s, -51d 01' 38"} (J2000) with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multi-peaked structure with an initial main peak of duration ~ 2 sec and lower level emission out to T+20 sec. This is followed by a second peak at T+ ~300 sec of duration ~30 sec seen only in the 15-50 keV band. The peak count rate was ~2500 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began taking data at 07:50:05 UT, 87 seconds after the BAT trigger. The XRT on-board centroid algorithm did not find a source in the image. Ground analysis reveals a possible faint source at the following coordinates: RA(J2000): 18h 27m 42.35s Dec(J2000): -51 00 51.2 with an error of 5.1 arcseconds (90% confidence). Further analysis of ground data is necessary to determine the properties of the possible source. The current flux is 8.3x10^-9 erg cm-2 s-1. UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm) filter starting 91 seconds after the BAT trigger. No afterglow candidate has been found in the initial data products. The overlap of the 8'x8' region for the list of sources generated on-board and the BAT error circle is 100%. No correction has been made for the expected extinction corresponding to E(B-V) of 0.07. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5576 SUBJECT: GRB 060919: TAROT optical observations DATE: 06/09/19 09:49:17 GMT FROM: Alain Klotz at CESR-CNRS Klotz, A. (CESR-OMP), Boer M. (OHP), Atteia J.L. (LATT-OMP) report: We imaged the field of GRB 060919 detected by SWIFT (trigger 230115) with the new TAROT robotic telescope (D=25cm) located at the La Silla observatory, Chile. First image was acquired 28.3s after the GRB trigger (5.2s after the notice). The field elevation decreased from only 2 degrees above horizon and weather conditions were good. Images were taken during the prompt emission. Date of trigger : t0 = 2006-09-19T07:48:38.880 First image is 60.0s exposure trailed. No OT is visible: t0+28.3s to t0+88.3s : R > 15.4 Second image is 30.0s exposure. No OT is visible: t0+94.2s to t0+124.2s : R > 15.8 We co-added a series of the 3 firsts not trailed exposures. No OT is visible: t0+94.2s to t0+196.4s : R > 15.9 Fourth non trailed image is a 90.0s exposure and covers the second gamma peak described by Guidorzi et al. GCNC 5575. No OT is visible: t0+292.3s to t0+382.3s : R > 15.8 Magnitudes were estimated with the nearby USNO-B1 stars and are not corrected for galactic dust extinction. N.B. Galactic coordinates are lon=343.8526 lat=-17.2471 and the galactic extinction in R band is 0.5 magnitudes estimated from D. Schlegel et al. 1998ApJ...500..525S. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5577 SUBJECT: GRB060919: XRT refined analysis DATE: 06/09/19 14:45:47 GMT FROM: Cristiano Guidorzi at INAF-OAB C. Guidorzi, P. Romano, A. Moretti, S. Vergani on behalf of the Swift XRT team report: we have analysed the first orbit of XRT data from GRB 060919 (Guidorzi et al., GCN Circ 5575). A 1.3 ks Photon Counting mode image provides a refined XRT position: RA(J2000) = 18h 27m 42.21s, Dec(J2000) = -51d 00m 50.4s with an uncertainty of 4.1 arcsec (90% containment). This position is 1.6 arcsec away from the previous XRT position and 56 arcsec from the onboard BAT position (Guidorzi et al., GCN Circ 5575). The X-ray light curve can be fit with a single power law with index 0.85 +- 0.2 (90%) from 100 to 1400 seconds after the BAT trigger. A power-law fit to the 0.3-10 keV spectrum yields a photon index of 1.7+-0.5 and a column density of (9+-4)x1e21 cm-2 (90%), significantly in excess of the Galactic hydrogen column density in the direction of the burst (6.4e20cm-2). The average unabsorbed flux of the first orbit is (1.1+-0.3)e-11 erg cm-2 s-1. If the burst decays at the current rate we estimate a 0.3-10 keV unabsorbed flux of ~1.2e-13 ergs cm-2 s-1 at T+24hr. This circular is an official product of the Swift XRT Team. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5578 SUBJECT: GRB 060919, Swift-BAT refined analysis DATE: 06/09/19 14:55:29 GMT FROM: Scott Barthelmy at NASA/GSFC G. Sato (GSFC/ISAS), L. Barbier (GSFC), S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), C. Guidorzi (Univ Bicocca&INAF-OAB), D. Hullinger (BYU-Idaho), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/ORAU), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC) on behalf of the Swift-BAT team: Using the data set from T-239 to T+950 sec from recent telemetry downlinks, we report further analysis of BAT GRB 060919 (trigger #230115) (Guidorzi, et al., GCN Circ. 5575). The BAT ground-calculated position is RA,Dec = 276.900, -50.994 deg {18h 27m 36.0s, -50d 59' 39.8"} (J2000) +- 1.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 29%. There is an initial FRED peak starting at T-1 sec, peaking at T+0, and lasting out to T+5 sec. There is smaller, 4-sec wide FRED-like peak starting at T+6 sec. There is an even smaller, 4-sec wide peak centered at T+24 sec. We note that our initial circular using the raw TDRSS rate lightcurves described a second episode of emission at T+300 sec. Now using the masked-tagged light curves, this second episode was due to a noisy detector in the instrument. T90 (15-350 keV) is 9.1 +- 0.2 sec (estimated error including systematics). The time-averaged spectrum from T-1.0 to T+9.0 is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.85 +- 0.19. The fluence in the 15-150 keV band is 5.5 +- 0.6 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T-0.49 sec in the 15-150 keV band is 2.2 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence level. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5579 SUBJECT: GRB 060919 : Faulkes South Telescope Observations DATE: 06/09/19 16:59:06 GMT FROM: Andrea Melandri at Liverpool John Moores U A. Melandri, A. Gomboc, R.J. Smith, N. Tanvir on behalf of the Robonet collaboration report: We imaged the field of GRB 060919 (Guidorzi et al., GCN 5575) with the Faulkes South Telescope starting at 10:36:10.50 UT (about 2.8 hours aftert the burst event). We acquired a first sequence of images in the R-band (6 exposures each lasting 150 seconds) and a second sequence in R and SDSS-I filters (12 exposures lasting 150 seconds in each filter). We did not detect any obvious optical counterpart inside the XRT refined error circle (Guidorzi et al., GCN 5577) down to a limiting magnitude of R > 19.5 (about 2.92 hours after the event). Further analysis and observation are still ongoing. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5580 SUBJECT: GRB060919: Swift/UVOT optical observations DATE: 06/09/20 10:58:39 GMT FROM: Pete Roming at PSU A. Breeveld (MSSL/UCL) and C. Guidorzi (Univ Bicoca&INAF-OAB) report on behalf of the Swift/UVOT team: The Swift/UVOT began taking data on 2006-09-19 73s after the burst (Guidorzi et al. GCN 5575). At the position of the XRT error circle (Guidorzi et al. GCN 5577) there are no new sources. In the summed UVOT images we obtain the following 3 sigma upper limits: Filter T_range(s) Exp(s) 3sig_UL(mag) V 73-11544 2310 20.24 B 674-24585 1330 21.02 U 650-24547 2202 20.88 UVW1 626-23633 1869 20.99 UVM2 602-12448 1134 21.10 UVW2 703-7232 424 20.65 White 91-18800 982.1 21.00 (160-650 nm) These magnitudes are not corrected for the expected extinction of E(B-V)=0.072