Gamma-ray Burst 180605A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN Circular #22764
  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,
  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,
  and
  W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr, on behalf of the GRS-Odyssey GRB team, report:
  The long-duration GRB 180605A was detected by Fermi (GBM; trigger 549889170), INTEGRAL (SPI-ACS), Konus-Wind, and Mars-Odyssey (HEND), at about 39565 s UT (10:59:25).
  We have triangulated it to a preliminary, 3 sigma error box whose coordinates are:

    ---------------------------------------------
     RA(2000), deg                 Dec(2000), deg
    ---------------------------------------------
    Center:
      47.510 (03h 10m 02s) -48.025 (-48d 01' 30")
    Corners:
      47.466 (03h 09m 52s) -48.645 (-48d 38' 43")
      48.461 (03h 13m 51s) -48.996 (-48d 59' 45")
      47.551 (03h 10m 12s) -47.403 (-47d 24' 11")
      46.582 (03h 06m 20s) -47.035 (-47d 02' 07")
    ---------------------------------------------
  

  The error box area is 3009 sq. arcmin, and its maximum dimension is 2.33 deg (the minimum one is 29.28 arcmin). The Sun distance was 73 deg.
  This box may be improved.
  A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB180605_T39565/IPN
  The time history and spectrum will be given in forthcoming GCN Circulars.
• GCN Circular #22765
  V. Sharma and A. Vibhute (IUCAA), V. Bhalerao (IIT-B), 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 the detection of a long GRB 180605A, which was also detected by IPN Triangulation (Svinkin D. et al., GCN 22764).
  The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks of emission with strongest peak at 10:59:28.5 UT. The measured peak count rate is 654.6 cts/s above the background in combined data of four quadrants, with a total of 7288 cts. The local mean background count rate was 495.4 cts/s. Using cumulative rates, we measure a T90 of 24.6 s.
  It was also clearly detected in the CsI anticoincidence (Veto) detector 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.
• GCN Circular #22766
  P Veres (UAH), C Meegan (UAH) and A von Kienlin (MPE) report on behalf of the Fermi GBM Team:
  "At 10:59:25.18 UT on 05 June 2018, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 180605A (trigger 549889170 / 180605458) which was also detected by the AstroSat CZTI (Sharma et al., GCN 22765) and IPN (Hurley et al., GCN 22764). The GBM on-ground location is consistent with the IPN position.
  The angle from the Fermi LAT boresight at the GBM trigger time is 61 degrees.
  The GBM light curve shows multiple overlapping peaks with a duration (T90) of about 24 s (50-300 keV). The time-averaged spectrum from T0s to T0+29.1 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.67 +/- 0.03 and the cutoff energy, parameterized as Epeak, is 663 +/- 42 keV.
  The event fluence (10-1000 keV) in this time interval is (2.36 +/- 0.04)E-5 erg/cm^2. The 1-sec peak photon flux measured starting from T0+8.3 s in the 10-1000 keV band is 7.2 +/- 0.2 ph/s/cm^2.
  A Band function fits the spectrum equally well with Epeak= 632 +/- 48 keV, alpha = -0.66 +/- 0.04 and beta = -2.65 +/- 0.38.
  The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."