GRB 210704B

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

At 16:25:18.89  UT on 04 July 2021, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 210704B (trigger 647108723 / 210704684).

The on-ground calculated location, using the GBM trigger
data, is RA = 203.44, DEC = -41.87 (J2000 degrees,
equivalent to 13 h 33 m, -41 d 52 '), with a statistical uncertainty
of 1.00 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which we have characterized as a core-plus-tail model, with 90% of
GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg
systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ).

The angle from the Fermi LAT boresight at the GBM trigger time is 87 degrees.

The GBM light curve shows multiple peaks
with a duration (T90) of about 43.5 s (50-300 keV).
The time-averaged spectrum from T0-0.5 s to T0+8.7 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.64 +/- 0.06 and
the cutoff energy, parameterized as Epeak, is 350.8 +/- 26.3 keV.

The event fluence (10-1000 keV) in this time interval is
(8.1 +/- 0.4)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+28.6 s in the 10-1000 keV band
is 16.1 +/- 0.4 ph/s/cm^2.


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/"

V. Prasad (IUCAA), P. Sawant (IUCAA), G. Waratkar (IITB), A. Vibhute
(IUCAA), V. Bhalerao (IITB), D. Bhattacharya (IUCAA), A. R. Rao
(IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat
CZTI collaboration: 

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al,
2020, arxiv:2011.07067) showed detection of a long GRB 210704B, which
was also detected by Fermi - GBM (Malacaria et al. 2021, GCN 30382
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 ). 

The source was clearly detected in the 20-200 keV energy range. The
light curve showed multiple peaks of emission with the strongest peak at
2021-07-04 16:25:47.5 UT. The measured peak count rate associated with
the burst is 296 (+47, -39) cts/s above the background in the combined
data of four quadrants, with a total of 3398 (+476, -466) cts. The local
mean background count rate was 552 (+2, -3) cts/s. Using cumulative
rates, we measure a T90 of 37 (+8, -7) s. 

It was also clearly detected in the CsI anticoincidence (Veto) detector
in the 100-500 keV energy range. The Veto light curve showed multiple
peaks of emission with the strongest peak at 2021-07-04 16:25:46.7 UT.
The measured peak count rate is 1642 (+95, -104) cts/s above the
background in the combined Veto data of four quadrants, with a total of
18239 (+789, -1081) cts. The local mean background count rate was 1864
(+5, -5) cts/s. We measure a T90 of 34 (+9, -3) s from the cumulative
Veto light curve. 

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.