Gamma-ray Burst 210925B

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN NOTICE
  

  TITLE:           GCN/FERMI NOTICE
  NOTICE_DATE:     Sat 25 Sep 21 03:48:30 UT
  NOTICE_TYPE:     Fermi-GBM Final Position
  RECORD_NUM:      0
  TRIGGER_NUM:     654225613
  GRB_RA:           47.990d {+03h 11m 58s} (J2000),
                    48.156d {+03h 12m 37s} (current),
                    47.609d {+03h 10m 26s} (1950)
  GRB_DEC:         -51.410d {-51d 24' 35"} (J2000),
                   -51.329d {-51d 19' 44"} (current),
                   -51.597d {-51d 35' 48"} (1950)
  GRB_ERROR:       1.18 [deg radius, statistical only]
  GRB_DATE:        19482 TJD;   268 DOY;   21/09/25
  GRB_TIME:        4808.68 SOD {01:20:08.68} UT
  GRB_PHI:         112.06 [deg]
  GRB_THETA:        77.15 [deg]
  E_RANGE:         50.000 - 300.000 [keV]
  LOC_ALGORITHM:   415 (Gnd S/W Version number)
  SUN_POSTN:       182.12d {+12h 08m 28s}   -0.92d {-00d 55' 03"}
  SUN_DIST:        114.91 [deg]   Sun_angle= 8.9 [hr] (West of Sun)
  MOON_POSTN:       47.60d {+03h 10m 25s}  +16.59d {+16d 35' 20"}
  MOON_DIST:        67.92 [deg]
  MOON_ILLUM:      84 [%]
  GAL_COORDS:      265.15,-54.14 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:       15.31,-64.35 [deg] ecliptic lon,lat of the burst (or transient)
  LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210925056/quicklook/glg_lc_medres34_bn210925056.gif
  LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210925056/quicklook/glg_locplot_all_bn210925056.png
  COMMENTS:        Fermi-GBM Final Position.  
  COMMENTS:        This Notice was ground-generated -- not flight-generated.  
  COMMENTS:        The LC_URL file should be available by the time this FINAL notice is produced.  
  COMMENTS:        This notice has human-in-the-loop processing.  
  

• GCN Circular #30890
  K. Hurley, on behalf of the IPN,
  I. G. Mitrofanov, D. V. Golovin, A. S. Kozyrev, M. L. Litvak, and A. B. Sanin, on behalf of the HEND-Odyssey GRB team,
  A. Ridnaia, S. Golenetskii, D. Frederiks, D. Svinkin, A. Lysenko, and T. Cline on behalf of the Konus-Wind team,
  A. Goldstein, M. S. Briggs, and C. Wilson-Hodge on behalf of the Fermi-GBM team,
  A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,
  S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu on behalf of the Swift-BAT team, and
  W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr, on behalf of the GRS-Odyssey GRB team, report:
  The long-duration GRB 210925B was detected by Fermi (GBM trigger 654225613), Konus-Wind, Mars-Odyssey (HEND), INTEGRAL (SPI-ACS), and Swift-BAT at about 4809 s UT (01:20:09). 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:
     48.817 (03h 15m 16s) -52.863 (-52d 51' 45")
   Corners:
     47.551 (03h 10m 12s) -53.723 (-53d 43' 21")
     50.006 (03h 20m 01s) -52.058 (-52d 03' 29")
     50.027 (03h 20m 06s) -51.978 (-51d 58' 41")
     47.579 (03h 10m 19s) -53.644 (-53d 38' 39")
   ---------------------------------------------
  

  The error box area is 335 sq. arcmin, and its maximum dimension is 2.3 deg (the minimum one is 2.5 arcmin). The Sun distance was 113 deg.
  This box may be improved.
  A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB210925_T04810/IPN/
  The time history and spectrum will be given in forthcoming GCN Circulars.
• GCN Circular #30892
  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., 2021, JApA, 42, 73) showed detection of a long GRB 210925B for which the IPN triangulation (Hurley et al., GCN 30890) was reported.
  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 2021-09-25 01:20:09.75 UT. The measured peak count rate associated with the burst is 887 (+190, -97) cts/s above the background in the combined data of four quadrants, with a total of 1482 (+214, -230) cts. The local mean background count rate was 471 (+5, -9) cts/s. Using cumulative rates, we measure a T90 of 6.3 (+1.9, -2.0) s.
  It was also clearly 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, ISAC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.