Gamma-ray Burst 170805A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN Circular #21427
  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,
  D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Kozlova, and T. Cline on behalf of the Konus-Wind team,
  S. Barthelmy, J. Cummings, H. Krimm, and D. Palmer, on behalf of the Swift-BAT team,
  A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,
  and
  W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr, on behalf of the GRS-Odyssey GRB team, report:
  A short-duration GRB 170805A (Ma et al., GCN Circ. 21421) was detected by Swift (BAT), Insight-HXMT, INTEGRAL (SPI-ACS), and Mars-Odyssey (HEND) at about 52714 s UT (14:38:34). 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:
     269.235 (17h 56m 56s) -18.322 (-18d 19' 19")
    Corners:
     269.038 (17h 56m 09s) -20.543 (-20d 32' 36")
     268.879 (17h 55m 31s) -20.576 (-20d 34' 34")
     269.536 (17h 58m 09s) -16.073 (-16d 04' 22")
     269.697 (17h 58m 47s) -16.036 (-16d 02' 11")
    ---------------------------------------------
  

  The error box area is 2378 sq. arcmin, and its maximum dimension is 4.6 deg (the minimum one is 8.8 arcmin). The Sun distance was 135 deg.
  This box may be improved.
  A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB170805_T52714/IPN
• GCN Circular #21502
  V. Sharma (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (IUCAA), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:
  Analysis of AstroSat CZTI data showed clear detection of short GRB 170805A (Insight-HXMT detection: Ma X. et al, GCN Circ. 21421) in the 40-200 keV energy range. The light curve shows single peak emission at 14:38:34.70 UT, around ~0.7 s before the Insight-HXMT trigger. The measured peak count rate is 4917.1 counts/s above the background in combined data of four quadrants, with a total 22361 counts. The local mean background count rate was 372.9 counts/s. Using cumulative rates, we measure a T90 of 0.96 s.
  It was clearly detected in the CsI anticoincidence detector (Veto) also as bright detection in the 100-500 keV energy range.
  CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.