Gamma-ray Burst 130716A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN Circular #15006
  During a TDRSS-275 outage between 10:25 and 10:59 UT this morning, Swift-BAT triggered on GRB 130716A (trigger #561974). Due to the TDRSS outage, prompt data was not available. Data has now been received. The burst occurred at 10:36:53 UTC.
  The BAT refined position is RA, Dec179.581,63.057, which is:

  RA (J2000)   11h 58m 19.4s
  Dec (J2000)  63d 03' 25"
  

  with an estimated uncertainty radius of 2.5 arcmin (90% confidence). The partial coding was 63%.
  The BAT lightcurve shows a double overlapping peak, the first peak smaller, with a total duration of about 0.8 seconds.
  The XRT began observing the field at 10:38:55 UT, 122 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 179.5770, 63.0529 which is equivalent to:

      RA(J2000)  = +11h 58m 18.5s
      Dec(J2000) = +63d 03' 10.6"
  

  with an uncertainty of 4.1 arcseconds (radius, 90% containment). This location is 15.7 arcseconds from the BAT onboard position, within the BAT error circle.
  UVOT data is not yet available.
  Burst Advocate for this burst is Stefan Immler (stefan.immler AT nasa.gov). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information:http://www.swift.psu.edu/too.html.)
• GCN Circular #15007
  M. H. Siegel (PSU) and S. Immler (GSFC) report on behalf of the Swift/UVOT team:
  The Swift/UVOT began settled observations of the field of GRB 130716A 120s after the BAT trigger (Cummings et al., GCN Circ. 15006). No optical afterglow consistent with the XRT 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 first finding chart (FC) exposure and subsequent exposures are:

  Filter    T_start(s)   T_stop(s)    Exp(s)   Mag
  white (fc)     120       270         147    >20.47 
  white          888      1038         147    >20.90 
  v             5858      6057         196    >19.17 
  b             5242      5442         196    >20.01
  u (fc)         334       583         245    >19.86
  uvw1          4832      5032         196    >19.61
  uvm2          4627      4827         196    >19.64
  uvw2          5653      5853         196    >20.05
  

  The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.01 in the direction of the burst (Schlegel et al. 1998).
• GCN Circular #15008
  W. Fong, E. Berger and R. Chornock (Harvard) report:
  "We observed the field of the short-duration GRB 130716A (Cummings et al., GCN 15006) with the Gemini Multi-Object Spectrograph mounted on the Gemini North 8-m telescope starting on Jul 17.253 UT (19.45 hr after the burst). We obtained ~15 min of r-band observations in 1" seeing. Calibrated to stars in the SDSS DR9 catalog, we do not detect any optical source within the reported XRT position to a 5-sigma limit of r>24.5 mag.
  We thank the Gemini staff for their assistance with these observations."
• GCN Circular #15010
  J. Norris (BSU), S. D. Barthelmy (GSFC), T. Sakamoto (AGU), N. Gehrels (GSFC)
  We report the spectral lag analysis for GRB 130716A (GCN Circ. 15506) based on the BAT data. Using 16-ms binned light curve, the spectral lag for the 25-50 keV to 100-350 keV bands is -2 (+50/-40) ms, and +11 (+25/-14) ms for the 15-25 keV to 50-100 keV bands. Although the lag value is not well constrained (relatively large errors), we believe this burst is more consistent with short burst category. There is no evidence for extended emission.
• GCN Circular #15011
  S. Foley (UCD) and C. Meegan (UAH) report on behalf of the Fermi GBM Team:
  "At 10:36:53.59 UT on 16 July 2013, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 130716A (trigger 395663816 / 130716442) which was also detected by the Swift/BAT (Cummings et al. 2013, GCN 15006). The GBM on-ground location is consistent with the Swift position.
  The GBM light curve consists of two overlapping pulses with a duration (T90) of about 0.8 s (50-300 keV). The time-averaged spectrum from T0-0.256 s to T0+0.576 s is adequately fit by a power law function with an exponential high-energy cutoff. The power law index is -0.23 (+0.28/-0.24) and the cutoff energy, parameterized as Epeak, is 635 (+184/-112) keV.
  The event fluence (10-1000 keV) in this time interval is (9.2 +/- 0.7)E-07 erg/cm^2. The 64-msec peak photon flux measured starting from T0+0.256 s in the 10-1000 keV band is 6.2 +/- 0.9 ph/s/cm^2.
  The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
• photometric redshift z = 2.2 +0.35 -0.37
  of host-galaxy: W.-F. Fong et al. 2022, ApJ 940, 56