Gamma-ray Burst 150702A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN Circular #17989
  G.Vianello (Stanford University), M.E. Monzani (SLAC), M. Axelsson (Stockholm University)
  report on behalf of the Fermi-LAT team:
  On July, 02, 2015 Fermi-LAT detected high-energy emission from GRB 150702A, which triggered Fermi-GBM at 23:56:38.55 UT (trigger 457574201 / 150702998).
  The LAT data from this burst were made available to the Fermi collaboration and to the public with an unusually long delay, due to an issue with ground software which affected the event reconstruction pipeline. This issue has now been solved.
  The best LAT on-ground location is found to be
  RA, Dec = 52.78, -57.00 (J2000)
  with an error radius of 0.36 deg (90 % containment, statistical error only).
  The GRB was outside the field of view of the LAT at the trigger time, but entered the FOV ~500 s after the trigger and exited again ~3000 s after the trigger.
  The data from the Fermi-LAT show a significant increase in the event rate that is spatially and temporally correlated with the trigger with high significance.
  The highest-energy photon is a 800 MeV event which is observed ~1200 seconds after the GBM trigger.
  A Swift ToO has been requested for this burst.
  The Fermi-LAT point of contact for this burst is Magnus Axelsson (magnusa@astro.su.se).
  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 #17990
  P. A. Evans (U. Leicester) reports on behalf of the Swift team:
  Swift has initiated a ToO observation of the Fermi/LAT GRB 150702A. Automated analysis of the XRT data will be presented online at http://www.swift.ac.uk/ToO_GRBs/00020541
  Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. These are not necessarily related to the Fermi/LAT event. 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; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).
  This circular is an official product of the Swift-XRT team.
• GCN Circular #17991
  P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'ai (INAF-IASFPA), T.G.R. Roegiers (PSU), L.M. McCauley (PSU), J.A. Kennea (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), C. Pagani (U. Leicester) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:
  Swift-XRT has performed follow-up observations of the Fermi/LAT-detected burst GRB 150702A (Vianello et al. GCN Circ. 17989), collecting 4.5 ks of Photon Counting (PC) mode data between T0+167.6 ks and T0+180.0 ks.
  Two uncatalogued X-ray sources have been detected, however none of them is above the RASS limit or shows definitive signs of fading. Therefore, at the present time we cannot identify which, if any, is the afterglow. Details of these sources are given below:
  Source 1:

    RA (J2000.0):  53.1085  =  03:32:26.05
    Dec (J2000.0): -57.0628  =  -57:03:46.1
    Error: 9.8 arcsec (radius, 90% conf.)
    Count-rate: (3.6 +/- 1.7)e-3 ct s^-1
    Flux: (1.42 +/- 0.67)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
  

  Source 2:

    RA (J2000.0):  52.7486  =  03:30:59.65
    Dec (J2000.0): -56.9320  =  -56:55:55.1
    Error: 7.7 arcsec (radius, 90% conf.)
    Count-rate: (1.57 [+0.85, -0.66])e-3 ct s^-1
    Flux: (6.3 [+3.4, -2.6])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)
  

  The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, are available at http://www.swift.ac.uk/ToO_GRBs/00020541.
  This circular is an official product of the Swift-XRT team.
• GCN Circular #17992
  D.Buckley, S. Potter, A.Kniazev, M.Kotze South African Astronomical Observatory
  E. Gorbovskoy, V. Lipunov, N.Tyurina, V.Kornilov, P.Balanutsa, A.Kuznetsov, E.Popova, D.Kuvshinov, Lomonosov Moscow State University, Sternberg Astronomical Institute
  R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias
  A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory
  K.Ivanov, O.Gres, N.M.Budnev, S.Yazev, O.Chuvalaev, V.A.Poleshchuk Irkutsk State University
  V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov, A.Gabovich Blagoveschensk Educational State University, Blagoveschensk
  V.Krushinski, I.Zalozhnih Ural Federal University, Kourovka
  Hugo Levato and Carlos Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)
  Carlos Lopez, Claudio Mallamaci and Federico Podest Observatorio Astronomico Felix Aguilar (OAFA)
  MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in SAAO automaticaly was starting survey on the FERMI GRB150702A error-box (ra=03 34 31 dec=-57 43 12 r=1.110000) 4575 sec after notice time and 4708 sec after trigger time at 2015-07-03 01:15:06 UT. The 5-sigma upper limit on our first (60s exposure) set is about 18.0 mag Any uncatalogued optical sources inside Fermi-LAT error box (Evans et al., GCN 17990) detected in this observations. No OT detected at XRT Source 1 and 2 positions (D'Avanzo et al., GCN 17991).
  The full covering map is available at httP://observ.pereplet.ru/images/GRB150702A_map.jpg .
  The message may be cited.
  
• GCN Circular #17993
  K. Hurley, on behalf of the IPN,
  I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin, on behalf of the HEND-Odyssey GRB team,
  S. Golenetskii, R. Aptekar, V. Pal'shin, D. Frederiks, D. Svinkin, and T. Cline on behalf of the Konus-Wind team,
  V. Connaughton, M. S. Briggs, C. Meegan, V. Pelassa, and A. Goldstein, on behalf of the Fermi GBM team,
  A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,
  S. Barthelmy, J. Cummings, N. Gehrels, H. Krimm, and D. Palmer, on behalf of the Swift-BAT team, and
  W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr, on behalf of the GRS-Odyssey GRB team, report:
  GRB 150702A, localized by Fermi-LAT (Vianello, Monzani, & Axelsson GCN=20 Circ. 17989), has been also observed by Fermi (GBM trigger 457574201),=20 Konus-Wind, INTEGRAL (SPI-ACS), Swift (BAT), and Mars Odyssey (HEND), so=20 far, at about 86198 s UT (23:56:38). The burst was outside the coded=20 field of view of the BAT.
  We have triangulated this GRB to a Konus-MarsOdyssey annulus centered at RA(2000)=3D95.937 deg (06h 23m 45s) Dec(2000)=3D+24.107 deg (+24d 06' 24= "),=20 whose radius is 88.902 =C2=B1 0.055 deg (3 sigma).
  This annulus intersects the Fermi-LAT 90% CL error circle (Vianello,=20 Monzani, & Axelsson, GCN Circ. 17989) to form an error box whose area is=20 about 5 times smaller than that of the LAT error circle, and whose corners are:

  -----------------------------------------------
      RA(2000), deg                 Dec(2000), deg
  -----------------------------------------------
  1 53.1503 (03h 32m 36s) -57.2987 (-57d 17' 55")
  2 53.2998 (03h 33m 12s) -57.2234 (-57d 13' 24")
  3 52.2673 (03h 29m 04s) -56.7738 (-56d 46' 26")
  4 52.1653 (03h 28m 40s) -56.8692 (-56d 52' 09")
  -----------------------------------------------
  

  Both XRT sources (D'Avanzo et al., GCN Circ. 17991) are outside the IPN=20 annulus and, hence, unlikely related to the GRB.
  A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB150702_T86198/IPN/
• GCN Circular #17994
  P. Jenke (UAH) reports on behalf of the Fermi GBM Team:
  "At 23:56:38.54 on July 2 2015, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 150702A (trigger 457574202/150702998) which was also detected by Fermi-LAT (G.Vianello et al. 2015, GCN 17989). The GBM on-ground location, using the Fermi GBM trigger data, is consistent with the LAT location and the IPN triangulation (K. Hurley et al. 2015, GCN 17993).
  The initial angle of the burst direction to the Fermi LAT boresight was 119 degrees.
  The GBM light curve consists of multiple peaks with a duration (T90) of about 45 s (50-300 keV). The time-averaged spectrum from T0+0s to T0+26s is well fit by a Band function with Epeak = 987 +/- 100 keV, Alpha = -0.91 +/- 0.04 and Beta = -2.4 +/- 0.2. The event fluence (10-1000 keV) in this time interval is (2.1 +/- 0.4)E-05 erg/cm^2. The 1.0-sec peak photon flux measured starting from T0+1.3 s in the 10-1000 keV band is 10.4 +/- 0.4 ph/s/cm^2.
  The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
• GCN Circular #17995
  S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik, M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline on behalf of the Konus-Wind team, report:
  The long-duration, hard-spectrum GRB 150702A (Fermi-LAT detection: Vianello, Monzani & Axelsson, GCN 17989; IPN triangulation: Hurley et al., GCN 17993; Fermi GBM detection: Jenke, GCN 17994) triggered Konus-Wind at T0=86198.645 s UT (23:56:38.645).
  The burst light curve starts, at ~T0-0.5 s, with a double-peaked pulse which is followed by the weaker flaring which extends till ~T0+70 s. The emission is seen up to ~18 MeV.
  As observed by Konus-Wind, the burst had a fluence of 5.50(-1.45,+1.86)x10^-5 erg/cm2, and a 64-ms peak energy flux, measured from T0+1.200 s, of 1.75(-0.61,+0.70)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+65.984 s) is best fit in the 20 keV - 18 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -1.24(-0.09,+0.11), and Ep = 2059(-903,+1940) keV (chi2 = 106/98 dof).
  The spectrum near the peak count rate (measured from T0 to T0+8.640 s) is best fit in the 20 keV - 18 MeV range by the power law with exponential cutoff model: with alpha = -1.11(-0.11,+0.14), and Ep = 2310(-1007,+2032) keV (chi2 = 103/97 dof).
  The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB150702_T86198/
  All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.