[vsnet-grb-info 20668] GRB 150605A: Fermi GBM observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22766
SUBJECT: GRB 150605A: Fermi GBM observation
DATE:    18/06/07 19:00:04 GMT
FROM:    Peter Veres at UAH  <veresp at gmail.com>

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."