Gamma-ray Burst 140611A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN Circular #16384
  S. Golenetskii, R. Aptekar, V. Pal'shin, D. Frederiks, D. Svinkin, and T. Cline on behalf of the Konus-Wind team,
  K. Hurley and J. Goldsten, on behalf of the MESSENGER NS GRB team,
  S. Barthelmy, J. Cummings, N. Gehrels, H. Krimm, and D. Palmer, on behalf of the Swift-BAT team, and
  A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, report:
  The short-duration, hard spectrum, bright GRB 140611A has been observed by Konus-Wind, Swift (BAT), MESSENGER (GRNS), and INTEGRAL (SPI-ACS), so far, at about 13864 s UT (03:51:04). The burst was outside the coded field of view of the BAT.
  We have triangulated it to a preliminary, 3 sigma error box whose coordinates are:

      ---------------------------------------------
       RA(2000), deg                 Dec(2000), deg
      ---------------------------------------------
      Center:
       349.931 (23h 19m 43s) -40.077 (-40d 04' 38")
      Corners:
       349.762 (23h 19m 03s) -40.115 (-40d 06' 54")
       350.246 (23h 20m 59s) -40.726 (-40d 43' 33")
       350.100 (23h 20m 24s) -40.039 (-40d 02' 21")
       349.615 (23h 18m 28s) -39.417 (-39d 25' 02")
      ---------------------------------------------
  

  The error box area is 674 sq. arcmin, and its maximum dimension is 1.4 deg (the minimum one is 15.6 arcmin).
  This box may be improved.
  The time history and spectrum will be given in a forthcoming GCN Circular.
• GCN Circular #16386
  J. R. Cummings on behalf of the Swift-BAT team
  Following the IPN Triangulation of GRB 140611A (Golenetskii et al., GCN Circ # 16384), a reexamination of the BAT image shows a sub-threshold source at the edge of the BAT field of view at RA, Dec 349.939, -40.111 which is:

  RA (J2000)   23h 19m 45.4s 		
  Dec (J2000) -40d 06' 41"
  

  with an estimated 90% uncertainty radius of 4 arcmin. This location is within the IPN error box.
  In BAT, this burst had two short peaks, the first 5 times brighter, each about 0.4 seconds long, separated by about 1.8 seconds. The total T90 was about 1.9 +/- 0.2 seconds. Because of the partial coding, a calibrated BAT spectrum is not possible, but the burst appears to be in the short-hard category.
  A Swift TOO is being performed.
• GCN Circular #16389
  S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik, M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lyssenko, and T. Cline on behalf of the Konus-Wind team, report:
  The short/hard GRB 140611A (IPN triangulation: Golenetskii at al., GCN 16384; Swift-BAT detection in ground analysis: Cummings, GCN 16386) triggered Konus-Wind at T0=13864.927 s UT (03:51:04.927).
  The burst light curve starts, at ~T0-0.1, with a rise of short, bright pulse with a duration of ~0.5 s, followed by a weaker, second pulse from ~T0-1.5 s to ~T0+2.2 s. The total duration of the burst is ~2.3 s. The emission is seen up to ~5 MeV.
  As observed by Konus-Wind, the burst had a fluence of 1.5(-0.3,+0.4)x10^-5 erg/cm2, and a 64-ms peak flux, measured from T0+0.256 s, of 4.5(-0.5,+0.5)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
  The time-averaged spectrum (measured from T0 to T0+8.448 s) is best fit in the 20 keV - 18 MeV range by the cutoff power law with the following model parameters: the photon index alpha = -0.68 (-0.18,+0.22), and the peak energy Ep = 1460(-360,+520) keV, chi2 = 111/98 dof. Fitting this spectrum with the Band model yields the same values of alpha and Ep with an upper limit on beta of -2.3.
  The spectrum near the maximum count rate (measured from T0 to T0+0.256 s) is best fit in the 20 keV - 5 MeV range by the cutoff power law with the following model parameters: the photon index alpha = -0.24(-0.14,+0.16), and the peak energy Ep = 1410(-160,+170) keV, chi2 = 69/68 dof.
  The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB140611_T13864/
  All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.
• GCN Circular #16390
  P.A. Evans, K.L. Page and A. Amaral-Rogers (U. Leicester) report on behalf of the Swift-XRT team:
  We have analysed 4.8 ks of XRT data for the IPN-detected burst: GRB 140611A, from 80.5 ks to 92.1 ks after the IPN trigger (Golenetskii et al., GCN Circ. 16384). The burst was also detected in ground analysis of BAT data (Cummings, GCN Circ. 16386). The data are entirely in Photon Counting (PC) mode. An X-ray source is detected within the IPN and BAT error regions. The refined XRT position is RA, Dec = 349.9173, -40.1044 which is equivalent to:

  RA (J2000): 23 19 40.15
  Dec(J2000): -40 06 16.0
  

  with an uncertainty of 5.5 arcsec (radius, 90% confidence). This position is 64 arcsec from the BAT ground position and 106 arcsec from the centre of the IPN error box. The source has a mean count rate of (1.9 +0.9,-0.7) x 10^-3 count s^-1 over this time interval. Within the 4-arcmin radius BAT error circle, we would expect approximately 0.25 serendipitous sources of at least this brightness. We cannot determine whether the source is fading and no further observations are planned.
  The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00020385.
  This circular is an official product of the Swift-XRT team.