//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8484 SUBJECT: GRB 081105 Swift/BAT and IPN Localization DATE: 08/11/06 01:00:17 GMT FROM: Jay R. Cummings at NASA/GSFC/Swift J. Cummings, S. Barthelmy, N. Gehrels, H. Krimm, and D. Palmer, on behalf of the Swift-BAT team S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, K. Hurley, and T. Cline on behalf of the Konus-Wind team, K. Yamaoka, M. Ohno, Y. Fukazawa, T. Takahashi, M. Tashiro, Y. Terada, T. Murakami, and K. Makishima on behalf of the Suzaku WAM team A. von Kienlin, G. Lichti, and A. Rau, on behalf of the INTEGRAL SPI-ACS GRB team, and M. Marisaldi, F. Fuschino, M. Galli, C. Labanti, E. Del Monte, F. Lazzarotto, L. Pacciani, and P. Soffitta on behalf of the AGILE team At 2008-11-05 T0=48372.403 s UT (13:26:12.403), a long soft GRB, GRB 081105 triggered Konus/Wind. The IPN was informed, and Swift/BAT, AGILE-MCAL, Suzaku/WAM, and INTEGRAL/SPI-ACS reported coincident rate increases. Ground analysis of BAT data (trigger #333811) yielded a significant image peak that was found to be coincident with the IPN timing triangulation annulus. The location of the burst was RA, Dec 3.966, 3.454, uncertainty radius of 2.5 arcmin, which is RA(J2000) = 00h 15m 51.8s Dec(J2000) = +03d 27' 14" The source was found onboard, but not with high enough significance to trigger an automatic burst response. The partial coding was only 2.5%. The burst was a single peak, about 10 seconds long. A Swift TOO has been requested and approved. The Swift narrow-field instruments should begin observing the burst at about 04:30 UT, 15 hours after the burst. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8487 SUBJECT: Swift-XRT observations of GRB 081105 DATE: 08/11/06 15:41:23 GMT FROM: Andy Beardmore at U Leicester A.P. Beardmore (U. Leicester) and J. Cummings (GSFC/UMBC) report on behalf of the Swift-XRT team. The Swift-XRT started observing the field of the Swift-BAT and IPN localization GRB 081105 (Cummings et al., GCN 8484) at 2008-11-06 05:18:07(UT), 15.8 hours after the trigger. In an exposure of 5ks we detect an X-ray source within the BAT error circle at RA, Dec = 3.95224, 3.47098, which is RA (J2000) = 00:15:48.5 Dec (J2000) = +03:28:15.5 with an uncertainty of 4.8 arcsec (radius, 90 percent confidence). The observed count rate is (7.6+/-2.0)e-3 count/s. At this stage we cannot tell whether the source is fading. Further Swift observations are planned. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8488 SUBJECT: UVOT/Swift observations of GRB081105 DATE: 08/11/06 16:07:53 GMT FROM: Patricia Schady at MSSL/Swift P.A. Curran (UCL-MSSL), P. Schady (UCL-MSSL) and J. Cummings (GSFC/UMBC), on behalf of the Swift/UVOT team. The Swift Ultra-Violet/Optical Telescope (UVOT) began settled observations of the Swift-BAT and IPN localization GRB 081105 (#333811; Cummings et al., GCN 8484) ~16 hours after the BAT trigger. No afterglow is detected at the XRT position (Beardmore et al., GCN 8487) in any filter. The 3-sigma limiting magnitudes in each of the observed UVOT filters are as follows: Filter T_start(dys) Exp(s) Mag UL (3sig) white 0.67 159 > 20.76 v 0.81 630 > 19.92 b 0.66 885 > 21.05 u 0.74 224 > 19.92 uvw1 0.73 886 > 20.75 uvw2 0.89 886 > 21.02 The values quoted above are in the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627). They are not corrected for the expected Galactic extinction corresponding to a reddening of E(B-V)=0.03 mag in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8489 SUBJECT: GRB 081105: Observations from OSN DATE: 08/11/06 21:59:26 GMT FROM: Antonio Deugarte at IAA-CSIC A. de Ugarte Postigo (ESO, Santiago), F. Aceituno & A. J. Castro-Tirado (IAA-CSIC, Granada) report on behalf of a larger collaboration: We have observed the field of GRB 081105 (Cummings et al. GCNC 8484) with the 1.5m OSN telescope in R and I bands. We do not detect any source within the XRT error box (Beardmore et al. GCNC 8487). The mean times and 3-sigma limits of the observations are the following: t-t0(days) Band Limit 1.2454 R > 21.3 1.2499 I > 20.7 Photometry is based on the star 0934-0003777 of USNO-B1.0 catalogue (R.A.: 3.953112, Dec.: +3.463859), assuming R=17.11 and I=16.54. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8492 SUBJECT: GRB 081105: GROND Upper Limits DATE: 08/11/07 07:53:48 GMT FROM: Christian Clemens at MPE C. Clemens, R. Filgas, J. Greiner, T. Kruehler, A. Yoldas (all MPE Garching), A. Kupcu Yoldas (ESO) and G. Szokoly (Eoetvoes Univ., Budapest) report on behalf of the GROND team: We observed the field of GRB 081105 (Swift trigger #333811; Cummings et al., GCN #8484) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m ESO/MPI telescope at La Silla Observatory (Chile). Observations started at 02:01 UT on November 6th, 2008, 12.6 hr after the GRB trigger with 23.0 min of total exposures in g'r'i'z' and 24.0 min in JHK. They were performed at an average seeing of 1.4" and at an average airmass of 1.2. As Ugarte Postigo et al. (GCN #8489), we do not detect any object within the 4.8'' Swift-XRT error circle reported by Beardmore et al. (GCN #8487) down to the following upper limits (all in AB system) of: g' > 23.3 mag, r' > 23.2 mag, i' > 22.5 mag, z' > 22.3 mag, J > 21.6 mag, H > 21.0 mag and K > 20.0 mag. These upper limits are derived based on calibrating the images against the GROND zeropoints as well as 2MASS field stars. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8495 SUBJECT: GRB 081105B: Fermi GBM detection DATE: 08/11/07 17:01:51 GMT FROM: Andreas von Kienlin at MPE Elisabetta Bissaldi (MPE) and A. von Kienlin (MPE) report on behalf of the Fermi GBM Team: "At 14:43:51.29 UT on 05 November 2008, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 081105B (trigger 247589032 / 081105614). The on-ground calculated location, using the GBM trigger data, is RA = 215.7 deg, Dec = 42.8 (J2000 degrees, equivalent to 14h 23m, 42d 48'), with an uncertainty of 12 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which is currently estimated to be 2 to 3 degrees). The angle from the Fermi LAT boresight is 87 degrees. This short GRB consists of a single peak with an estimated T90 (8-1000 keV) of 180 ms and T50 (8-1000 keV) of 64 ms. The spectral fit to this weak event is poorly constrained. A fit of the time-averaged spectrum from T0-0.067 s to T0-0.019 s by a simple power law function yields an index of -1.17 +/- 0.05 (chi squared 311 for 421 d.o.f.). The event fluence (8-1000 keV) in this time interval is (2.28 +/- 0.11)E-07 erg/cm^2. The photon flux on the 16 ms timescale measured starting from T0-0.067 s in the 8-1000 keV band is 20 +/- 3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8522 SUBJECT: Further Swift-XRT observations of the probable GRB 081105. DATE: 08/11/16 01:15:46 GMT FROM: Andy Beardmore at U Leicester A.P. Beardmore (U. Leicester), D.N. Burrows (PSU), J.R. Cummings (NASA/UMBC) report on behalf of the Swift-XRT team. The Swift-XRT reobserved the field of the Swift-BAT and IPN localisation GRB 081105 (Cummings et al., GCN 8484) for a further 9.8 ks starting at 2008-11-12T04:15:51(UT), 6.62 days after the trigger. Using a 10 pixel radius extraction region we detect 9 counts at the position of the XRT source reported in GCN 8487 (Beardmore & Cummings) compared with 1.28+/-0.20 estimated background counts. The Bayesian method of Kraft et al. (1991 ApJ 374 344) produces a 3 sigma confidence level on the expected source counts of S_min = 1.40 to S_max = 20.08, suggesting the source is detected. (The lower limit on the expected source counts, S_min, approaches zero when the confidence level reaches 4.4 sigma.) The estimated source count rate is (1.07+/-0.40)e-3 count/s (where the quoted error is 1 sigma), compared with a value of 0.0065 +/-0.0015 count/s from the earlier observation. By fitting the low counts per bin data using Cash statistics, we find the source has faded with a decay slope of 1.01 +0.38-0.32. Both the source intensity and decay is comparable to those seen in other long GRBs at this stage of their outburst (e.g. see http://www.swift.ac.uk/xrt_curves/allcurves.php). We suggest the X-ray source reported in GCN 8487 was the counterpart to the BAT/IPN localisation and its decaying nature gives further weight to a GRB interpretation. This circular is an official product of the Swift-XRT team.