Gamma-ray Burst 130518B

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN Circular #14682
  J. R. Cummings (UMBC/CRESST/GSFC) reports on behalf of the Swift-BAT team:
  At 10:50:38 UTC, Swift-BAT triggered on GRB 130418A (trigger # 556105). A sub-threshold source was found onboard. In ground analysis, a source was confirmed at RA, Dec 321.555, -20.148, which is:

  RA (J2000)    21h 26m 13.2s
  Dec (J2000)  -20d 08m 53s
  

  with an estimated uncertainty of 1.8 arcmin radius (90% confidence).
  The burst as seen in BAT was a single FRED peak of approximately 15 seconds duration.
  A Swift TOO request has been submitted and approved to locate the afterglow.
• GCN Circular #14683
  J. R. Cummings (UMBC/CRESST/GSFC) and H. A. Krimm (USRA/CRESST/GSFC) report on behalf of the Swift-BAT team:
  In the first sentence of GCN Circular 14682 (Cummings), we incorrectly named the GRB. The burst that provided Swift/BAT trigger #556105 should be named GRB 130518B, consistent with the subject line. We apologize for any confusion.
• GCN Circular #14690
  Boris Sbarufatti (INAF-OAB/PSU) reports on behalf of the Swift XRT team
  We have analysed 4.2 ks of XRT data for GRB 130518B (Cummings GCN Circ. 14862), from 184.0 ks to 196.1 ks after the BAT trigger. The data are all in Photon Counting (PC) mode. No bright X-ray afterglow is detected inside the refined BAT error circle. The 3sigma upper limit is of 4.3 x 10^-3 cts/s.
  This corresponds to an observed 0.3-10 keV flux of 1.6 x 10^-13 erg/cm2/s (assuming a typical GRB spectrum with photon spectral index of 2). If we consider the Galactic absorption in this direction (3.5 x 10^20 cm^-2; Kalberla et al. 2005) this corresponds to an unabsorbed flux of 1.8 x 10^-13 erg/cm2/s.
• GCN Circular #14694
  H. A. Krimm (GSFC/USRA) and J. R. Cummings (GSFC/UMBC) for the Swift-BAT team:
  We report further analysis of BAT GRB 130518B (trigger #556105) (Cummings, GCN Circ. 14682).
  The time-averaged spectrum covering 10 seconds of event data (which includes most of the burst) is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.39 +- 0.14. The fluence in the 15-150 keV band is 8.0 x 10^-7 erg/cm2. All the quoted errors are at the 90% confidence level.