[vsnet-grb-info 20997] GRB 180806A: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  23095
SUBJECT: GRB 180806A: Fermi GBM detection
DATE:    18/08/07 17:35:57 GMT
FROM:    Christian Malacaria at U of Alabama/MSFC  <christian.malacaria at nasa.gov>

C. Malacaria (NASA-MSFC/USRA), R. Hamburg (UAH), and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 22:38:59.66 UT on 06 August 2018, the Fermi Gamma-Ray Burst
Monitor triggered and located GRB 180806A
(trigger 555287944 / 180806944).

The event was also possibly detected by MASTER OT
(Lipunov et al. 2018, GCN 23091) and COATLI (Watson et al. 2018,
GCN 23092, GCN 23094) and triggered a Swift/XRT ToO
(Evans et al. 2018, GCN 23093).
The GBM on-ground location and the MASTER position are consistent.

The angle from the Fermi LAT boresight at the
GBM trigger time is 66 degrees.

The GBM light curve consists of a single peak
with a duration (T90) of about 15.6 +/- 0.8 s (50-300 keV).
The time-averaged spectrum from T0-1.5 s to T0+16.9 s is
best fit by a Band function with Epeak = 482.40 +/- 31.2,
alpha index = -0.95 +/- 0.02 and beta index = -2.37 +/- 0.19.

The event fluence (10-1000 keV) in this time interval is
(2.197 +/- 0.039)E-05 erg/cm^2. The 1-sec peak photon flux
Measured starting from T0+4.9 s in the 10-1000 keV band
is 14.3 +/- 0.3 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."