[vsnet-grb-info 26506] GRB 201011A: Fermi GBM detection of a likely Long GRB in the direction of SGR 1830-0645

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  28606
SUBJECT: GRB 201011A: Fermi GBM detection of a likely Long GRB in the direction of SGR 1830-0645
DATE:    20/10/12 21:10:54 GMT
FROM:    Oliver J Roberts at USRA/NASA  <oliver.roberts at nasa.gov>

O.J. Roberts (USRA) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 15:06:24.66 UT on 11 October 2020, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 201011A (trigger 624121589 / 201011629),
which was also detected by the AGILE (Ursi et al. 2020, GCN 28605).
The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 281.1, Dec = -5.7 (J2000 degrees, equivalent to
J2000 18h 44m , -05d 43'), with a statistical uncertainty of 2.4 degrees.

The angle from the Fermi LAT boresight at the GBM trigger time is 35 degrees.

The GBM light curve consists of multiple pulses
with a duration (T90) of about 126.2 s (50-300 keV).
The time-averaged spectrum from T0-1.8 s to T0+124.2 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -1.18 (+0.09/-0.08) and
the cutoff energy, parameterized as Epeak, is 138.0 (+19.6/-14.4) keV.

The event fluence (10-1000 keV) in this time interval is
(9.25 +/- 0.52)E-06 erg/cm^2. The 1s peak photon flux measured
starting from T0+5.44 s in the 10-1000 keV band
is 5.8 +/- 0.3 ph/s/cm^2.

We note that this event is in the direction of SGR 1830-0645 
(K.L. Page et al. 2020, GCN 28594). While we cannot conclusively rule out 
an association with SGR 1830-0645, the GBM spectrum and time history 
are suggestive of a long GRB and not a Magnetar transient. 
Analysis is ongoing to confirm the source.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"