Gamma-ray Burst 110815A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN Circular #12277
  K. Hurley, on behalf of the Mars Odyssey and MESSENGER GRB teams,
  I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin, on behalf of the HEND-Odyssey GRB team,
  W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr, on behalf of the GRS-Odyssey GRB team,
  S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, D. Svinkin, and T. Cline on behalf of the Konus-Wind team,
  D. M. Smith, R. P. Lin, J. McTiernan, R. Schwartz, and W. Hajdas, on behalf of the RHESSI GRB team,
  K. Yamaoka, M. Ohno, Y. Hanabata, Y. Fukazawa, T. Takahashi, M. Tashiro, Y. Terada, T. Murakami, and K. Makishima on behalf of the Suzaku WAM team,
  S. Barthelmy, J. Cummings, N. Gehrels, H. Krimm, and D. Palmer, on behalf of the Swift-BAT team,
  J. Goldsten, on behalf of the MESSENGER NS GRB team, and
  E. Costa, E. Del Monte, I. Donnarumma, Y. Evangelista, M. Feroci, I. Lapshov, F. Lazzarotto, L. Pacciani, M. Rapisarda, P. Soffitta, for the SuperAGILE team, report:
  GRB110815A at 34857 s UT was detected by SuperAGILE (outside the coded FoV), Konus-Wind, MESSENGER GRNS, Odyssey HEND, RHESSI, Suzaku WAM, and Swift BAT (also outside the coded FoV). We have triangulated it to a preliminary, 3 sigma error box whose area is 195 sq. arcmin and whose coordinates are:

      RA(2000)                 DEC(2000)
  85.297 o =  5 h 41 m 11.2 s  +32.442 = 32 o 26 '  31 "  (CENTER)
  85.183 o =  5 h 40 m 43.9 s  +32.409 = 32 o 24 '  31 "  (CORNER)
  85.464 o =  5 h 41 m 51.3 s  +32.753 = 32 o 45 '  12 "  (CORNER)
  85.130 o =  5 h 40 m 31.1 s  +32.113 = 32 o 06 '  48 "  (CORNER)
  85.411 o =  5 h 41 m 38.6 s  +32.474 = 32 o 28 '  26 "  (CORNER)
  

  A map has been posted at ssl.berkeley.edu/ipn3/110815. This error box can be improved. The time history and spectrum will be given in a forthcoming GCN Circular. A Swift ToO has been requested.
  
• GCN Circular #12278
  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 intense GRB 110815A (localized by IPN: Hurley et al., GCN 12277) triggered Konus-Wind at T0=3D34855.971s UT (09:40:55.971)
  The burst light curve shows two peaks separated by ~13 s. The total duration of the burst is ~20s. The emission is seen up to ~8 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB110815_T34855/
  As observed by Konus-Wind the burst had a fluence of (5.0 =B1 0.5)x10-5 erg/cm2, and a 64-ms peak flux, measured from T0+1.920 s, of (1.8 =B1 0.1)x10-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
  The time-integrated spectrum of the burst (measured from T0 to T0+19.200 s) is best fitted in the 20 keV - 10 MeV range by the GRB (Band) model, for which: the low-energy photon index alpha =3D -0.85 (-0.1, +0.1), the high energy photon index beta =3D -2.5 (-0.3, +0.2), the peak energy Ep =3D 251(-25, +25) keV, chi2 =3D 73/87 dof.
  The spectrum at the maximum count rate (measured from T0 to T0+2.816 s) is best fitted in the 20 keV - 10 MeV range by the GRB (Band) model, for which: the low-energy photon index alpha =3D -0.12 (-0.13, +0.14), the high energy photon index beta =3D -2.8 (-0.3, +0.2), the peak energy Ep =3D 300(-20, +22) keV, chi2 =3D 99/87 dof.
  All the quoted results are preliminary. All the quoted errors are at the 90% confidence level.
• GCN Circular #12280
  N. Ohmori, M. Akiyama, M. Yamauchi (Univ. of Miyazaki), M. Ohno, Y. Hanabata, T. Uehara, T. Takahashi, M. Mizuno, Y. Fukazawa (Hiroshima U.), K. Yamaoka (Aoyama Gakuin U.), S. Sugita (Nagoya U.), T. Yasuda, Y. Terada, W. Iwakiri, K. Takahara, M. Asahina, S. Kobayashi, M. Tashiro (Saitama U.), M. Kokubun, T. Takahashi (ISAS/JAXA), Y. E. Nakagawa (Waseda U.), Y. Urata, P. Tsai, C-J. Chuang (NCU), K. Nakazawa, K. Makishima (Univ. of Tokyo), on behalf of the Suzaku WAM team, report:
  The long GRB110815A (localized by IPN; Hurley et al., GCN12277) triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV at 09:40:57.524 UT (=T0).
  The observed light curve shows two peaks starting at T0 s, ending at T0+17 s, with a duration (T90) of about 13 seconds. The fluence in 100 - 1000 keV was 2.84 (-0.04, +0.05) x 10^-5 erg/cm^2. The 1-s peak flux measured from T0+2 s was 19.62 (-0.82, +0.92) photons/cm^2/s in the same range.
  Preliminary result shows that the time-averaged spectrum from T0 s to T0+17 s is well fitted by a power-law with exponential cutoff model:

   dN/dE ~  E^{-alpha} * exp(-(2-alpha)*E/Epeak) with
   alpha       1.45 (-0.13, +0.13), and
   Epeak       300 (-25, +20) keV (chi^2/d.o.f. = 102.1/88).
  

  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 #12282
  A. Rowlinson (U Leicester), B.L. Porterfield; (PSU), M.H. Siegel (PSU), and C. B. Markwardt (GSFC) report on behalf of the Swift-XRT team:
  We have analyzed 3.9 ks of XRT data for GRB 110815A (Hurley et al. GCN Circ. 12277), from 208 ks to 216 ks after the IPN trigger. The data are entirely in Photon Counting (PC) mode. The data are centred on RA, Dec = (85.297, 32.442). The XRT field of view therefore covers about 80% of the IPN error box. No source is detected in the XRT image with a 3 sigma upper limit of 2.4e-3 count s^-1.
  Swift/UVOT observed the field of GRB 110815A (Hurley et al. GCN Circ. 12277) for 1.9 ks from 208 ks to 216 ks after the IPN trigger. Data were obtained entirely in the white filter. We do not detect any new source within the IPN error box down to a 3-sigma magnitude limit of 21.64 on the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627). The magnitude limit is not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.02 in the direction of the burst (Schlegel et al. 1998).
  This circular is an official product of the Swift-XRT team.