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TITLE:   GCN CIRCULAR
NUMBER:  33397
SUBJECT: GRB 230304C: Fermi GBM Final Real-time Localization
DATE:    23/03/04 22:10:27 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM  <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 22:01:39 UT on 4 Mar 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230304C (trigger 699660104.796088 / 230304918).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 280.7, Dec = -10.8 (J2000 degrees, equivalent to J2000 18h 42m, -10d 48'), with a statistical uncertainty of 5.2 degrees.

The angle from the Fermi LAT boresight is 63.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230304918/quicklook/glg_skymap_all_bn230304918.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230304918/quicklook/glg_healpix_all_bn230304918.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230304918/quicklook/glg_lc_medres34_bn230304918.gif

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TITLE:   GCN CIRCULAR
NUMBER:  33401
SUBJECT: GRB 230304C: AstroSat CZTI detection
DATE:    23/03/06 06:43:30 GMT
FROM:    Gaurav Waratkar at IIT,Bombay  <gauravwaratkar@iitb.ac.in>

P K. Navaneeth (IUCAA), R. Gopalakrishnan (IUCAA), G. Waratkar (IITB), 
A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka 
University/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., 
2021, JApA, 42, 73) showed the detection of a GRB 230304C which was also 
detected by Fermi-GBM (Fermi GBM team, GCN Circ. 33397).

The source was clearly detected in the 20-200 keV energy range. The 
light curve peaks at 2023-03-04 22:01:39.5 UTC. The measured peak count 
rate associated with the burst is 93 (+42, -15) counts/s above the 
background in the combined data of three quadrants (out of four), with a 
total of 410 (+138, -140) counts. The local mean background count rate 
was 374 (+2, -3) counts/s. Using cumulative rates, we measure a T90 of 
9.34 (+2, -4) s.

It was also 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, URSC, IUCAA, SAC, 
and PRL. The Indian Space Research Organisation funded, managed, and 
facilitated the project.