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GRB 251129B

GCN Circular 42960

Subject

IPN triangulation of GRB 251129B (short/hard)

Date

2025-12-02T18:31:26Z (a day ago)

From

Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>

Via

Web form

A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin
on behalf of the HEND/Mars Odyssey team,

D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia,
and T. Cline on behalf of the Konus-Wind team,

E. Burns on behalf of the IPN,

S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, A. Tohuvavohu,
and J. DeLaunay on behalf of the Swift-BAT team,

and

W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr,
and A.S. Gardner on on behalf of the GRS-Odyssey GRB team,
report:

The short-duration GRB 251129B
(AstroSat-CZTI detection: Salunke et al., GCN 42958Loading...
 
 )
was detected by Konus-Wind, Swift(BAT), Mars-Odyssey (HEND),
and AstroSat (CZTI), at about 35494 s UT (09:51:34).
The burst was outside the coded field of view of the BAT.

We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
 ---------------------------------------------
  RA(2000), deg                 Dec(2000), deg
 ---------------------------------------------
 Center:
  124.862 (08h 19m 27s) +76.391 (+76d 23' 28")
 Corners:
  118.469 (07h 53m 53s) +78.048 (+78d 02' 53")
  119.970 (07h 59m 53s) +77.774 (+77d 46' 26")
  129.621 (08h 38m 29s) +74.606 (+74d 36' 22")
  128.692 (08h 34m 46s) +74.931 (+74d 55' 51")
 ---------------------------------------------
The error box area is 617 sq. arcmin, and its maximum
dimension is 4.32 deg (the minimum one is 2.6 arcmin).
The Sun distance was 117 deg.

The localization may be improved.

A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB251129_T35496/IPN/
The HEALPix triangulation map is the multi-order HEALPix in units of
probability density.

The Konus-Wind time history and spectrum will be given
in a forthcoming GCN Circular.

GCN Circular 42958

Subject

GRB 251129B: AstroSat CZTI detection

Date

2025-12-02T18:22:35Z (a day ago)

From

Anuraag Arya at IIT Bombay <aryaanuraag910@gmail.com>

Via

Web form

S. Salunke (IUCAA), M. Tembhurnikar (IUCAA), Harsha K. H. (IUCAA), A. Arya (IITB), A. Goyal (IITB), G. Waratkar (Caltech/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 short-duration GRB 251129B which was also detected by Konus Wind (IPN Notices).

The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed a peak of emission with the strongest peak at 2025-11-29T09:51:34 UTC. The measured peak count rate associated with the burst is 1480 (+927, -83) counts/s above the background in the combined data of three quadrants (out of four), with a total of 128 (+30, -29) counts. The local mean background count rate was 212 (+20, -44)) counts/s. Using cumulative rates, we measure a T90 of  0.14 (+0.04, -0.03) s.

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