Gamma-ray Burst 130327B

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN Circular #14344
  F. Longo (University of Trieste and INFN Trieste), A. Giuliani (INAF/IASF Milan), M. Marisaldi (INAF/IASF Bologna), E. Del Monte (INAF/IAPS Rome), F. Lazzarotto, I. Donnarumma, Y. Evangelista, M. Feroci, L. Pacciani, P. Soffitta, E. Costa, I. Lapshov, M. Rapisarda (INAF/IAPS Rome), G. Barbiellini, (INFN Trieste), A. Bulgarelli, F. Gianotti, M. Trifoglio, G. Di Cocco, C. Labanti, F. Fuschino, M. Galli (INAF/IASF Bologna), A. Chen, S. Mereghetti, F. Perotti, P. Caraveo (INAF/IASF Milan), M. Tavani, V. Vittorini, A. Argan, G. Piano, S. Sabatini, M. Cardillo (INAF/IASF Rome), G. Pucella (ENEA Frascati), A. Pellizzoni, A. Trois (INAF/OA Cagliari), M. Pilia (ASTRON), S. Vercellone (INAF/IASF Palermo), P. W. Cattaneo, A. Rappoldi (INFN Pavia), P. Picozza, A. Morselli, E. Striani, (INFN Roma-2), M. Prest, E. Vallazza (Universita` dell'Insubria), P. Lipari, D. Zanello (INFN Roma-1), P. Giommi, C. Pittori, F. Lucarelli, P. Santolamazza, F. Verrecchia (ASDC) and G. Valentini (ASI), on behalf of the AGILE Team, report:
  The AGILE Gamma Ray Imaging Detector (GRID) detected emission from GRB 130327B, localised by Fermi/GBM (http://gcn.gsfc.nasa.gov/other/386065447.fermi). The GRB occurred at approximately 28 deg off-axis in the field of view of the AGILE/GRID.
  A preliminary analysis of the AGILE/GRID data in temporal coincidence with the GRB shows a significant excess of gamma-ray events above 80 MeV at the location of the event. Most of the events detected by the AGILE/GRID have times between ~ t0 + 9 sec and t0 + 14 sec where t0 is 27 March 2013 at 08:24:04.05 UT.
  The GRB was also detected also by the AGILE/MCAL, operating in the energy range 0.5 - 100 MeV.
  A more detailed analysis of the AGILE data is in progress. More observations of this interesting burst are strongly encouraged.
  This message may be cited.
• GCN Circular #14346
  V.Chaplin (UAH) and G. Fitzpatrick (UCD) report on behalf of the Fermi GBM Team:
  "At 08:24:04.05 UT on 27 March 2013, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 130327B (trigger 386065447 / 130327350), which was also detected by several instruments on-board the AGILE spacecraft (Del Monte et al. GCN 14344).
  The on-ground calculated location, using the GBM trigger data, is RA = 214.9, DEC = -74.6 degrees, with an uncertainty of 1 degree (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 at the GBM trigger time was 47 degrees. The Fermi Observatory executed a maneuver following this trigger and tracked the burst location for the next 2.5 hours, subject to Earth-angle constraints.
  The GBM light curve consists of multiple spikes on top of a gradual rise and decay. The main emission occurs between T0 and T0+35 seconds. The total duration (T90) is about 62 s (50-300 keV). The time-averaged spectrum from T0-0.8 s to T0+33 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.57 +/- 0.02 and the cutoff energy, parameterized as Epeak, is 341 +/- 6.3 keV.
  The spectrum also fits a Band function with Epeak = 334 +/- 7 keV, alpha = -0.56 +/- 0.02, and beta = -3.4 +/- 0.4.
  The event fluence (10-1000 keV) in this time interval is (5.176 +/- 0.057)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+32.4 s in the 8-1000 keV band is 12.7 +/- 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 #14347
  M. Ohno (Hiroshima U.), J. McEnery (NASA/GSFC), G. Vianello (Stanford), J.L. Racusin (NASA/GSFC) and E. Troja (CRESST) report on behalf of the Fermi-LAT team:
  At 08:24:04 on March 28th, 2013, Fermi LAT detected high energy emission from GRB 130327B, which was also detected by Fermi-GBM (trigger 386065447 / 130327350 ; Chaplin and Fitzpatrick GCN 14346) and by AGILE (Del Monte et al. GCN 14344).
  The best LAT on-ground location is found to be RA, DEC 218.09, -69.51 (J2000) with an error radius of 0.17 deg (68% containment, statistical error only), this was about 50 deg from the LAT boresight at the time of the trigger and triggered an autonomous repoint of the spacecraft.
  The data from the Fermi LAT show a significant increase in the event rate within 5 degree of the GBM location after the GBM trigger that is spatially and temporally correlated with the GBM emission with high significance. More than 20 photons above 100 MeV are observed within 100 seconds.
  A Swift TOO observation has been requested.
  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 #14348
  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-duration GRB 130327B (AGILE detection: Longo et al., GCN 14344; Fermi-GBM detection: Chaplin and Fitzpatrick, GCN 14346; Fermi-LAT detection: Ohno et al., GCN 14347) triggered Konus-Wind at T0=3D30247.662s UT (08:24:07.662)
  The light curve shows a multi-peaked structure with a total duration of ~35 s. The emission is seen up to 12 MeV.
  The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB130327_T30247/
  As observed by Konus-Wind, the burst had a fluence of (5.6 =B1 0.5)x10-5 erg/cm2, and a 64-ms peak flux, measured from T0+4.352s, of (4.9 =B1 0.5)x10-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
  The time-integrated spectrum (measured from T0 to T0+40.704 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) function with the following model parameters: the low-energy photon index alpha =3D -0.59 =B1 0.08, the high energy photon index beta =3D -2.65 =B1 0.25, the peak energy Ep =3D 278 =B1 18 keV, chi2 =3D 122/97 dof.
  The spectrum at the maximum count rate (measured from T0 to T0+7.936 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) function with the following model parameters: the low-energy photon index alpha =3D -0.62 =B1 0.13, the high energy photon index beta =3D -2.6 =B1 0.4, the peak energy Ep =3D 314 =B1 39 keV, chi2 =3D 97.6/92 dof.
  All the quoted results are preliminary.
• GCN Circular #14353
  H. A. Krimm (CRESST/GSFC/USRA) and V. Mangano (INAF-IASFPA) for the Swift team:
  We have analysed 7.9 ks of XRT data for the AGILE/Konus/Fermi-detected burst: GRB 130327B (Longo et al, GCN 14344; Chaplin & Fitzpatrick, GCN 14346; Ohno et al, GCN 14347; Golenetskii et al, GCN 14348), from 110.1 ks to 128.6 ks after the Fermi/GBM trigger. The data are entirely in Photon Counting (PC) mode. An X-ray source is detected within the Fermi/LAT error circle. The refined XRT position is RA, Dec = 217.87488, -69.40345 which is equivalent to:

  RA (J2000): 14 31 29.97
  Dec(J2000): -69 24 12.4
  

  with an uncertainty of 4.1 arcsec (radius, 90% confidence). This position is 459 arcsec from the Fermi/LAT position. We cannot determine at the present time whether the source is fading.
  The count rate level is 4 x 10^-3 counts/s. Further Swift observations have been scheduled.
• GCN Circular #14357
  Y. Ishida, M. Tashiro, Y. Terada, T. Yasuda, H. Ueno, S. Sugimoto (Saitama U.), K. Yamaoka (Nagoya U.), M. Ohno, T. Kawano, K. Takaki, R. Nakamura, Y. Fukazawa (Hiroshima U.), M. Yamauchi, M. Akiyama, N. Ohmori, E. Mochinaga (Univ. of Miyazaki), S. Sugita (Ehime U.), Y. E. Nakagawa, M. Kokubun, T. Takahashi (ISAS/JAXA), W. Iwakiri (RIKEN), Y. Hanabata (ICRR), Y. Urata (NCU), K. Nakazawa, K. Makishima (Univ. of Tokyo) on behalf of the Suzaku WAM team, report:
  The long GRB 130327B (Chaplin et al GCN14346) was detected by the the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV at 08:24:04.751 UT (=T0).
  The observed light curve shows double-peaked structure starting at T0-1s, ending at T0+33s with a duration (T90) of about 30 seconds. The fluence in 100 - 1000 keV was 3.29(+0.15/-0.21)x10^-5 erg/cm^2. The 1-s peak flux measured from T0+23s was 2.23 photons/cm^2/s in the same energy range.
  Preliminary result shows that the time-averaged spectrum from T0-1s to T0+33s is well fitted by a power-law with exponential cutoff model :

     dN/dE ~  E^{-alpha} * exp(-(2-alpha)*E/Epeak) with
     alpha       0.89(+0.46/-0.56), and
     Epeak       484(+64/-50) keV (chi^2 / d.o.f. = 11.1/13).
  

  All the quoted errors are at statistical 90% confidence level, in which the systematic uncertainties are included.
  The light curves for this burst will be available at: http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html
• GCN Circular #14398
  H. A. Krimm (CRESST/GSFC/USRA) and E. Troja (NASA/GSFC/CRESST) for the Swift team:
  Swift carried out an additional 4.6 ksec observation of the field containing GRB 130327B (e.g. Longo et al, GCN 14344; Ohno et al, GCN 14347), starting at 2013-04-18 12:43:13 UT, approximately 22 days after the burst. The source reported in Krimm & Mangano (GCN 14353) as a possible afterglow to GRB 130327B is still detected at a rate of 0.002 =B1 0.001 cts/s (0.3-10 keV), which is statistically consistent with the rate reported in GCN 14353. Since we would=20 expect a GRB afterglow to have faded over this time period, we conclude that the XRT source is not associated with GRB 130327B, and is instead a background source, possibly an AGN. No further Swift observations are planned.