Gamma-ray Burst 130325A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN Circular #14329
  D. Tierney (UCD) reports on behalf of the Fermi GBM Team:
  "At 04:51:54.30 UT on 25 March 2013, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 130325A (trigger 385879917 / 130325203).
  The on-ground calculated location, using the GBM trigger data, is RA = 130.71, DEC = -21.12 (J2000 degrees, equivalent to 08 h 42 m, -21 d 07 '), with an uncertainty of 2.15 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 51.0 degrees.
  The GBM light curve consists of a single bright pulse with a duration (T90) of 9.7 s (50-300 keV). The time-averaged spectrum from T0+0.003 s to T0+9.216 s is best fit by a Band function with Epeak = 202.20 (+17.50/-15.60) keV, alpha = -0.73 (+0.06/-0.05), and beta = -2.18 (+0.09/-0.12).
  The event fluence (10-1000 keV) in this time interval is (8.25 +/- 0.27)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+1.8 s in the 10-1000 keV band is 12.9 +/- 0.3 ph/s/cm^2.
  The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
• GCN Circular #14332
  G. Vianello (Stanford), J. McEnery (NASA/GSFC), M. Ohno (Hiroshima U.), J Racusin and E. Troja (CRESST) report on behalf of the Fermi-LAT team:
  The Fermi Large Area Telescope (LAT) detected emission from GRB 130325A (GBM trigger 130325203/385879917).
  This burst was detected over a 1300 s integration following the GBM trigger using the P7SOURCE data class. This burst seems unusual because despite being within the field of view of the LAT at the time of the GBM trigger, it was not detected by the LAT during the prompt phase, which lasted 10 s (GCN 14329).
  The best LAT on-ground location is found to be RA, DEC 122.78, -18.90 (J2000) with an error radius of 0.25 deg (68% containment, statistical error only), this was 51 deg from the LAT boresight at the time of the trigger and triggered an autonomous repoint of the spacecraft at 04:52:31.48 UT.
  A Swift ToO has been submitted.
  The Fermi LAT point of contact for this burst is Julie McEnery (julie.mcenery@nasa.gov).
  The Fermi LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.
• GCN Circular #14336
  P. A. Evans (U. Leicester) reports on behalf of the Swift team:
  Swift has initiated a series of observations, tiled on the sky, of the Fermi/LAT GRB 130325A. Automated analysis of the XRT data will be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00013
  Any uncatalogued X-ray sources detected in this analysis will be reported on this website. The probability of finding serendipitous sources, unrelated to the Fermi/LAT event is high: any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration.
  Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; and 2009, MNRAS, 397, 1177).
  This circular is an official product of the Swift-XRT team.
• GCN Circular #14338
  S. Golenetskii, R.Aptekar, D. Frederiks, E. Mazets, V. Pal'shin, P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf of the Konus-Wind team, report:
  The long GRB 130325A (Fermi-GBM detection: Tierney, GCN 14329; Fermi-LAT detection: Vianello et al., GCN 14332) triggered Konus-Wind at T0=3D17516.880s UT (04:51:56.880)
  The light curve shows a single pulse with a total duration of ~8 s. The emission is seen up to 6 MeV.
  The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB130325_T17516/
  As observed by Konus-Wind, the burst had a fluence of (8.1 =B1 1.4)x10-6 erg/cm2, and a 64-ms peak flux, measured from T0+0.704s, of (3.7 =B1 0.4)x10-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
  The time-integrated spectrum (measured from T0 to T0+8.448 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) function with the following model parameters: the low-energy photon index alpha =3D -0.90 =B1 0.18, the high energy photon index beta =3D -2.4 =B1 0.3, the peak energy Ep =3D 186 =B1 28 keV, chi2 =3D 59.8/78 dof.
  All the quoted results are preliminary.