Gamma-ray Burst 130708A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN Circular #14997
  J. R. Cummings reports on behalf of the Swift-BAT team
  At 11:43:03.7 Swift-BAT triggered on GRB 130708A (trigger 560515). No significant source was found onboard, and rate-trigger processing was terminated prematurely by a pre-planned slew. A significant source was found in ground analysis at RA, Dec 17.474, 0.003, which is:

  RA (J2000)   01h 09m 53.7s
  Dec (J2000)  00d 00' 11.9"
  

  with an estimated 90% error radius of 2.4 arcmin. This position is 5.0 degrees from the location found by Fermi-GBM for trigger 394976587, which has an estimated error of 2.2 degrees. The partial coding was 11%.
  We note that this position is 1.6 arcmin from a Seyfert I galaxy at Z = 0.16, [VV2003c] J010946.5-000023.
  The BAT lightcurve shows a double-peaked long GRB. The T90 of the GRB was about 9 +/- 1 seconds, with a spectral power-law index of 1.38 +/- 0.28 and a fluence of (7.8 +/- 1.8) x 10^-6 ergs/cm^2 in the 15-150 keV BAT energy range. Error estimates are 90% confidence.
  A Swift TOO request has been approved to locate the afterglow with XRT. Since this burst was not located onboard, the usual automated analysis products are not available.
• GCN Circular #14999
  G. Fitzpatrick (UCD) reports on behalf of the Fermi GBM Team:
  At 11:43:04.27 UT on 08 July 2013, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 130708A (trigger 394976587/130708488) which was also detected by the Swift/BAT (Cummings et al., GCN Circ. 14997). The GBM on-ground location is consistent with the Swift position.
  The GBM light curve consists of a single peak with a duration (T90) of about 14 s (50-300 keV). The time-averaged spectrum from T0 s to T0 + 8 s is adequately fit by a power law function with an exponential high-energy cutoff. The power law index is -0.9 +/- 0.1 and the cutoff energy, parameterized as Epeak, is 158 +/- 16 keV
  The event fluence (10-1000 keV) in this time interval is (2.3 +/- 0.1)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+5.8 s in the 10-1000 keV band is 1.0 +/- 0.07 ph/s/cm^2.
  The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog.
• GCN Circular #15001
  A. Maselli (INAF-IASF Palermo) and A. Breeveld (MSSL-UCL) report on behalf of the Swift XRT and UVOT teams:
  The Swift/XRT started observing the field of the BAT ground-detected GRB 130708A (Cummings, GCN Circ. 14997) on 2013-07-09 at 14:49:07 UT, 97564 s after the BAT trigger. In 3881 s of XRT data in Photon Counting mode we detected no significant X-ray source within the BAT error circle. The 3-sigma upper limit at the reported BAT position is 4.0E-03 cts/s.
  The Swift/UVOT began settled observations of the field of GRB 130708A 97557 s after the BAT trigger. No optical afterglow consistent with the BAT position is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the initial exposures are:

  Filter         T_start(s)   T_stop(s)      Exp(s)         Mag
  
  white            97741       107968         1001         >21.6
  v                97926       103874         1037         >20.1
  u                97557       107909         1804         >21.4
  

  The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.03 in the direction of the burst (Schlegel et al. 1998).
  This circular is an official product of the Swift XRT and UVOT teams.