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GRB 231020B

GCN Circular 34862

Subject

GRB 231020B: Fermi GBM Final Real-time Localization

Date

2023-10-20T21:46:18Z (2 years ago)

From

Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

Via

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

At 21:35:52 UT on 20 Oct 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231020B (trigger 719530557.906538 / 231020900).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 221.4, Dec = 15.6 (J2000 degrees, equivalent to J2000 14h 45m, 15d 35'), with a statistical uncertainty of 1.0 degrees.

The angle from the Fermi LAT boresight is 98.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231020900/quicklook/glg_skymap_all_bn231020900.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/bn231020900/quicklook/glg_healpix_all_bn231020900.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231020900/quicklook/glg_lc_medres34_bn231020900.gif

GCN Circular 34864

Subject

GRB 231020B: BALROG localization (Fermi Trigger 719530557 / GRB 231020900)

Date

2023-10-21T07:02:45Z (2 years ago)

From

Jochen Greiner at MPE <jcgrog@mpe.mpg.de>

Via

T. Preis, B. Biltzinger, J. Burgess & J. Greiner (all MPE Garching) report:

The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger
719530557 at 21:35:52 on 20 Oct. 2023 were automatically fitted for spectrum
and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427;
Berlato et al. 2019, ApJ 873, 60).

The best-fit position (1 sigma statistical errors) is:
RA(2000.0) = 221.6+/-0.4 deg
Decl.(2000.0) = 17.6+/-0.6 deg
We estimate an additional systematic error of 1 deg.

Further details are available at:
https://grb.mpe.mpg.de/grb/GRB231020900/

The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB231020900/healpix

The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB231020900/json

GCN Circular 34879

Subject

GRB 231020B: AstroSat CZTI detection

Date

2023-10-25T06:43:53Z (2 years ago)

From

Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>

Via

Web form

P. K. Navaneeth (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 231020B which was also detected by Fermi - GBM (Fermi GBM Team, GCN Circ. 34862Loading...
 
 ).

The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2023-10-20 21:35:57.50 UTC. The measured peak count rate associated with the burst is 148 (+30, -16) counts/s above the background in the combined data of two quadrants (out of four), with a total of 1242 (+296, -361) counts. The local mean background count rate was 177 (+1, -3) counts/s. Using cumulative rates, we measure a T90 of 34 (+8, -16) s. 

The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2023-10-20 21:35:55.27 UTC. The measured peak count rate associated with the burst is 274 (+74, -45) counts/s above the background in the combined data of all quadrants, with a total of 1637 (+667, -683) counts. The local mean background count rate was 1501 (+5, -6) counts/s. We measure a T90 of 25 (+11, -15) s from the cumulative Veto light curve.

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.

CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb