Gamma-ray Burst 251118A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 18 Nov 25 20:31:59 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      46
TRIGGER_NUM:     785190695
GRB_RA:          149.833d {+09h 59m 20s} (J2000),
                 150.087d {+10h 00m 21s} (current),
                 149.343d {+09h 57m 22s} (1950)
GRB_DEC:         -46.983d {-46d 58' 59"} (J2000),
                 -47.108d {-47d 06' 28"} (current),
                 -46.743d {-46d 44' 35"} (1950)
GRB_ERROR:       15.58 [deg radius, statistical plus systematic]
GRB_INTEN:       97 [cnts/sec]
DATA_SIGNIF:     7.00 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        20997 TJD;   322 DOY;   25/11/18
GRB_TIME:        73890.09 SOD {20:31:30.09} UT
GRB_PHI:          68.00 [deg]
GRB_THETA:        55.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      1.98
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      78%  GRB
2nd_MOST_LIKELY:  13%  Generic SGR
DETECTORS:       0,1,1, 0,0,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       234.46d {+15h 37m 50s}  -19.43d {-19d 25' 40"}
SUN_DIST:         72.14 [deg]   Sun_angle= 5.6 [hr] (West of Sun)
MOON_POSTN:      217.50d {+14h 30m 00s}  -19.14d {-19d 08' 15"}
MOON_DIST:        60.85 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      275.00,  6.34 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      177.70,-53.82 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251118855/quicklook/glg_lc_medres34_bn251118855.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 77.85,-17.38 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 18 Nov 25 20:32:11 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      67
TRIGGER_NUM:     785190695
GRB_RA:          161.283d {+10h 45m 08s} (J2000),
                 161.584d {+10h 46m 20s} (current),
                 160.703d {+10h 42m 49s} (1950)
GRB_DEC:         -33.850d {-33d 51' 00"} (J2000),
                 -33.987d {-33d 59' 11"} (current),
                 -33.587d {-33d 35' 11"} (1950)
GRB_ERROR:       10.32 [deg radius, statistical plus systematic]
GRB_INTEN:       124 [cnts/sec]
DATA_SIGNIF:     12.70 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        20997 TJD;   322 DOY;   25/11/18
GRB_TIME:        73890.09 SOD {20:31:30.09} UT
GRB_PHI:          63.98 [deg]
GRB_THETA:        70.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      4.89
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      47%  GRB
2nd_MOST_LIKELY:  41%  Generic SGR
DETECTORS:       0,1,1, 0,0,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       234.46d {+15h 37m 50s}  -19.43d {-19d 25' 40"}
SUN_DIST:         65.40 [deg]   Sun_angle= 4.9 [hr] (West of Sun)
MOON_POSTN:      217.50d {+14h 30m 00s}  -19.14d {-19d 08' 17"}
MOON_DIST:        51.52 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      274.95, 22.07 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      178.33,-38.10 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251118855/quicklook/glg_lc_medres34_bn251118855.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 77.85,-17.38 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 18 Nov 25 20:32:20 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      71
TRIGGER_NUM:     785190695
GRB_RA:          157.250d {+10h 29m 00s} (J2000),
                 157.538d {+10h 30m 09s} (current),
                 156.694d {+10h 26m 47s} (1950)
GRB_DEC:         -37.867d {-37d 52' 00"} (J2000),
                 -38.000d {-37d 59' 58"} (current),
                 -37.610d {-37d 36' 37"} (1950)
GRB_ERROR:       4.33 [deg radius, statistical plus systematic]
GRB_INTEN:       941 [cnts/sec]
DATA_SIGNIF:     71.00 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        20997 TJD;   322 DOY;   25/11/18
GRB_TIME:        73890.09 SOD {20:31:30.09} UT
GRB_PHI:          66.00 [deg]
GRB_THETA:        65.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      2.80
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      70%  GRB
2nd_MOST_LIKELY:  29%  Generic SGR
DETECTORS:       0,1,1, 0,0,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       234.46d {+15h 37m 50s}  -19.43d {-19d 25' 40"}
SUN_DIST:         68.10 [deg]   Sun_angle= 5.1 [hr] (West of Sun)
MOON_POSTN:      217.50d {+14h 30m 01s}  -19.14d {-19d 08' 19"}
MOON_DIST:        54.94 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      274.21, 16.94 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      177.17,-43.20 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251118855/quicklook/glg_lc_medres34_bn251118855.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 77.85,-17.38 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 18 Nov 25 20:32:17 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      58
TRIGGER_NUM:     785190695
GRB_RA:          153.160d {+10h 12m 38s} (J2000),
                 153.430d {+10h 13m 43s} (current),
                 152.640d {+10h 10m 33s} (1950)
GRB_DEC:         -43.560d {-43d 33' 35"} (J2000),
                 -43.689d {-43d 41' 18"} (current),
                 -43.312d {-43d 18' 43"} (1950)
GRB_ERROR:       7.00 [deg radius, statistical only]
DATA_SIGNIF:     10.00 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        20997 TJD;   322 DOY;   25/11/18
GRB_TIME:        73890.09 SOD {20:31:30.09} UT
GRB_PHI:          67.00 [deg]
GRB_THETA:        59.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4173 (Gnd S/W Version number)
SUN_POSTN:       234.46d {+15h 37m 50s}  -19.43d {-19d 25' 40"}
SUN_DIST:         70.36 [deg]   Sun_angle= 5.4 [hr] (West of Sun)
MOON_POSTN:      217.50d {+14h 30m 00s}  -19.14d {-19d 08' 18"}
MOON_DIST:        58.32 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      274.85, 10.49 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      177.69,-49.68 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251118855/quicklook/glg_lc_medres34_bn251118855.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_785190695.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file will not be created/available until ~15 min after the trigger.  
COMMENTS:        The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 18 Nov 25 20:32:53 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      91
TRIGGER_NUM:     785190695
GRB_RA:          151.050d {+10h 04m 12s} (J2000),
                 151.310d {+10h 05m 14s} (current),
                 150.548d {+10h 02m 12s} (1950)
GRB_DEC:         -45.700d {-45d 42' 00"} (J2000),
                 -45.826d {-45d 49' 33"} (current),
                 -45.457d {-45d 27' 24"} (1950)
GRB_ERROR:       3.45 [deg radius, statistical plus systematic]
GRB_INTEN:       4676 [cnts/sec]
DATA_SIGNIF:     243.20 [sigma]
INTEG_TIME:      1.024 [sec]
GRB_DATE:        20997 TJD;   322 DOY;   25/11/18
GRB_TIME:        73890.09 SOD {20:31:30.09} UT
GRB_PHI:          68.00 [deg]
GRB_THETA:        55.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO:      0.83
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      98%  GRB
2nd_MOST_LIKELY:   1%  Generic Transient
DETECTORS:       0,1,1, 0,0,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       234.46d {+15h 37m 50s}  -19.43d {-19d 25' 40"}
SUN_DIST:         71.52 [deg]   Sun_angle= 5.5 [hr] (West of Sun)
MOON_POSTN:      217.51d {+14h 30m 02s}  -19.14d {-19d 08' 24"}
MOON_DIST:        59.94 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      274.90,  7.87 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      177.61,-52.29 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251118855/quicklook/glg_lc_medres34_bn251118855.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 77.85,-17.38 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 18 Nov 25 20:33:02 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      95
TRIGGER_NUM:     785190695
GRB_RA:          157.900d {+10h 31m 36s} (J2000),
                 158.191d {+10h 32m 46s} (current),
                 157.338d {+10h 29m 21s} (1950)
GRB_DEC:         -36.817d {-36d 49' 00"} (J2000),
                 -36.950d {-36d 57' 00"} (current),
                 -36.559d {-36d 33' 32"} (1950)
GRB_ERROR:       3.43 [deg radius, statistical plus systematic]
GRB_INTEN:       4944 [cnts/sec]
DATA_SIGNIF:     543.30 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        20997 TJD;   322 DOY;   25/11/18
GRB_TIME:        73890.09 SOD {20:31:30.09} UT
GRB_PHI:          66.00 [deg]
GRB_THETA:        65.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      0.98
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      98%  GRB
2nd_MOST_LIKELY:   1%  Generic Transient
DETECTORS:       0,1,1, 0,0,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       234.46d {+15h 37m 50s}  -19.43d {-19d 25' 41"}
SUN_DIST:         67.74 [deg]   Sun_angle= 5.1 [hr] (West of Sun)
MOON_POSTN:      217.51d {+14h 30m 02s}  -19.14d {-19d 08' 26"}
MOON_DIST:        54.38 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      274.08, 18.10 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      177.07,-42.04 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251118855/quicklook/glg_lc_medres34_bn251118855.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 77.85,-17.38 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 18 Nov 25 20:33:25 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      0
TRIGGER_NUM:     785190695
GRB_RA:          155.720d {+10h 22m 53s} (J2000),
                 156.000d {+10h 24m 00s} (current),
                 155.180d {+10h 20m 43s} (1950)
GRB_DEC:         -41.040d {-41d 02' 23"} (J2000),
                 -41.171d {-41d 10' 16"} (current),
                 -40.787d {-40d 47' 11"} (1950)
GRB_ERROR:       4.00 [deg radius, statistical only]
DATA_SIGNIF:     15.30 [sigma]
DATA_INTERVAL:   9.216 [sec]
GRB_DATE:        20997 TJD;   322 DOY;   25/11/18
GRB_TIME:        73890.09 SOD {20:31:30.09} UT
GRB_PHI:          66.00 [deg]
GRB_THETA:        62.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       234.46d {+15h 37m 50s}  -19.43d {-19d 25' 41"}
SUN_DIST:         68.84 [deg]   Sun_angle= 5.2 [hr] (West of Sun)
MOON_POSTN:      217.51d {+14h 30m 03s}  -19.14d {-19d 08' 30"}
MOON_DIST:        56.28 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      274.99, 13.63 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      178.05,-46.53 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251118855/quicklook/glg_lc_medres34_bn251118855.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_785190695.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        This is likely a Long GRB.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file will not be created/available until ~15 min after the trigger.  
COMMENTS:        The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 18 Nov 25 20:33:32 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      1
TRIGGER_NUM:     785190695
GRB_RA:          157.770d {+10h 31m 05s} (J2000),
                 158.057d {+10h 32m 14s} (current),
                 157.217d {+10h 28m 52s} (1950)
GRB_DEC:         -39.370d {-39d 22' 11"} (J2000),
                 -39.504d {-39d 30' 12"} (current),
                 -39.113d {-39d 06' 45"} (1950)
GRB_ERROR:       3.48 [deg radius, statistical only]
DATA_SIGNIF:     20.70 [sigma]
DATA_INTERVAL:   11.264 [sec]
GRB_DATE:        20997 TJD;   322 DOY;   25/11/18
GRB_TIME:        73890.09 SOD {20:31:30.09} UT
GRB_PHI:          65.00 [deg]
GRB_THETA:        64.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       234.46d {+15h 37m 50s}  -19.43d {-19d 25' 41"}
SUN_DIST:         67.50 [deg]   Sun_angle= 5.1 [hr] (West of Sun)
MOON_POSTN:      217.51d {+14h 30m 03s}  -19.14d {-19d 08' 31"}
MOON_DIST:        54.62 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      275.41, 15.89 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      178.72,-44.29 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251118855/quicklook/glg_lc_medres34_bn251118855.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_785190695.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        This is likely a Long GRB.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file will not be created/available until ~15 min after the trigger.  
COMMENTS:        The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 18 Nov 25 20:33:42 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      2
TRIGGER_NUM:     785190695
GRB_RA:          158.210d {+10h 32m 50s} (J2000),
                 158.499d {+10h 34m 00s} (current),
                 157.652d {+10h 30m 36s} (1950)
GRB_DEC:         -38.390d {-38d 23' 23"} (J2000),
                 -38.524d {-38d 31' 25"} (current),
                 -38.132d {-38d 07' 54"} (1950)
GRB_ERROR:       2.02 [deg radius, statistical only]
DATA_SIGNIF:     43.20 [sigma]
DATA_INTERVAL:   14.336 [sec]
GRB_DATE:        20997 TJD;   322 DOY;   25/11/18
GRB_TIME:        73890.09 SOD {20:31:30.09} UT
GRB_PHI:          65.00 [deg]
GRB_THETA:        65.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       234.46d {+15h 37m 50s}  -19.43d {-19d 25' 41"}
SUN_DIST:         67.28 [deg]   Sun_angle= 5.1 [hr] (West of Sun)
MOON_POSTN:      217.51d {+14h 30m 03s}  -19.14d {-19d 08' 33"}
MOON_DIST:        54.21 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      275.17, 16.90 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      178.43,-43.27 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251118855/quicklook/glg_lc_medres34_bn251118855.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_785190695.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        This is likely a Long GRB.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file will not be created/available until ~15 min after the trigger.  
COMMENTS:        The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 18 Nov 25 20:33:52 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      3
TRIGGER_NUM:     785190695
GRB_RA:          160.130d {+10h 40m 31s} (J2000),
                 160.425d {+10h 41m 42s} (current),
                 159.561d {+10h 38m 15s} (1950)
GRB_DEC:         -36.760d {-36d 45' 35"} (J2000),
                 -36.896d {-36d 53' 43"} (current),
                 -36.499d {-36d 29' 54"} (1950)
GRB_ERROR:       1.00 [deg radius, statistical only]
DATA_SIGNIF:     56.10 [sigma]
DATA_INTERVAL:   16.384 [sec]
GRB_DATE:        20997 TJD;   322 DOY;   25/11/18
GRB_TIME:        73890.09 SOD {20:31:30.09} UT
GRB_PHI:          64.00 [deg]
GRB_THETA:        67.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       234.46d {+15h 37m 50s}  -19.43d {-19d 25' 41"}
SUN_DIST:         65.97 [deg]   Sun_angle= 4.9 [hr] (West of Sun)
MOON_POSTN:      217.51d {+14h 30m 04s}  -19.14d {-19d 08' 35"}
MOON_DIST:        52.60 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      275.65, 19.08 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      179.10,-41.10 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251118855/quicklook/glg_lc_medres34_bn251118855.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_785190695.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        This is likely a Long GRB.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file will not be created/available until ~15 min after the trigger.  
COMMENTS:        The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 18 Nov 25 20:40:49 UT
NOTICE_TYPE:     Fermi-GBM Final Position
RECORD_NUM:      0
TRIGGER_NUM:     785190695
GRB_RA:          160.440d {+10h 41m 46s} (J2000),
                 160.736d {+10h 42m 57s} (current),
                 159.869d {+10h 39m 29s} (1950)
GRB_DEC:         -36.450d {-36d 27' 00"} (J2000),
                 -36.586d {-36d 35' 08"} (current),
                 -36.188d {-36d 11' 16"} (1950)
GRB_ERROR:       1.00 [deg radius, statistical only]
GRB_DATE:        20997 TJD;   322 DOY;   25/11/18
GRB_TIME:        73890.09 SOD {20:31:30.09} UT
GRB_PHI:          64.00 [deg]
GRB_THETA:        66.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       234.46d {+15h 37m 51s}  -19.43d {-19d 25' 45"}
SUN_DIST:         65.77 [deg]   Sun_angle= 4.9 [hr] (West of Sun)
MOON_POSTN:      217.57d {+14h 30m 17s}  -19.16d {-19d 09' 50"}
MOON_DIST:        52.37 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      275.71, 19.48 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      179.19,-40.71 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251118855/quicklook/glg_lc_medres34_bn251118855.gif
LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251118855/quicklook/glg_locplot_all_bn251118855.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 was generated completely by automated pipeline processing.  
COMMENTS:        This is likely a Long GRB.

GCN Circular #42743
The Fermi GBM team reports the detection of a likely LONG GRB
At 20:31:30 UT on 18 Nov 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251118A (trigger 785190695.089648 / 251118855).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 160.4, Dec = -36.5 (J2000 degrees, equivalent to J2000 10h 41m, -36d 30'), with a statistical uncertainty of 1.0 degrees.
The angle from the Fermi LAT boresight is 66.0 degrees.
The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251118855/quicklook/glg_skymap_all_bn251118855.png
The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251118855/quicklook/glg_healpix_all_bn251118855.fit
The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251118855/quicklook/glg_lc_medres34_bn251118855.gif
GCN Circular #42745
T. Preis (University of Innsbruck) & J. Greiner (MPE Garching) report:
The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger 785190695 at 20:31:30 on 18 Nov. 2025 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 is:
```
RA(2000.0) = 160.0 deg
Decl.(2000.0) = -34.9 deg
```
The 1 sigma statistical error radius is 2.0 deg. We estimate an additional systematic error of 2 deg.
Further details are available at: https://grb.mpe.mpg.de/grb/GRB251118855/
The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB251118855/healpix
The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB251118855/json

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Wed 19 Nov 25 04:08:57 UT
NOTICE_TYPE:     Fermi-LAT Offline Position
TRIGGER_NUM:     785190695
GRB_RA:          160.083d {+10h 40m 20s} (J2000),
                 160.381d {+10h 41m 31s} (current),
                 159.508d {+10h 38m 02s} (1950)
GRB_DEC:         -34.576d {-34d 34' 33"} (J2000),
                 -34.712d {-34d 42' 41"} (current),
                 -34.315d {-34d 18' 52"} (1950)
GRB_ERROR:       10.43 [arcmin radius, 90% containment, statistical only]
GRB_DATE:        20997 TJD;   322 DOY;   25/11/18
GRB_TIME:        73890.09 SOD {20:31:30.09} UT
TRIGGER_ID:      0x20000000
MISC:            0x40000000
SUN_POSTN:       234.79d {+15h 39m 09s}  -19.50d {-19d 30' 05"}
SUN_DIST:         66.52 [deg]   Sun_angle= 5.0 [hr] (West of Sun)
MOON_POSTN:      221.25d {+14h 44m 59s}  -20.46d {-20d 27' 46"}
MOON_DIST:        54.97 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:      274.43, 20.94 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      177.66,-39.22 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi LAT Offline position.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        It is the result of human-in-the-loop processing.  
COMMENTS:        This is a human generated position of a LAT ground detection for GRB 251118A.  
COMMENTS:        This source corresponds to GBM trigger.

GCN Circular #42750
P. A. Evans (U. Leicester) reports on behalf of the Swift team:
Swift has initiated a ToO observation of the Fermi/LAT-detected event GRB 251118A. Automated analysis of the XRT data will be presented online at https://www.swift.ac.uk/ToO_GRBs/00021890 Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. These are not necessarily related to the Fermi/LAT event. Any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration.
Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).
This circular is an official product of the Swift-XRT team.
GCN Circular #42752
R. Gupta (NASA GSFC) and T. Khalil (Univ. of Johannesburg) report on behalf of the Fermi-LAT Collaboration:
On November 18 2025, Fermi-LAT detected high-energy emission from GRB 251118A, which was also detected by Fermi-GBM (trigger 785190695 / 251118855, GCN 42743). The best LAT on-ground location is found to be:
RA, Dec = 160.08, -34.58 (J2000)
with an error radius of 0.17 deg (90 % containment, statistical error only). This was 69 deg from the LAT boresight at the time of the GBM trigger (T0 = 20:31:30.09 UT).
The data from the Fermi-LAT shows a significant increase in the event rate that is spatially and temporally correlated with the GBM emission with high significance. The photon flux above 100 MeV in the time interval 0 - 1.5 ks after the GBM trigger is (1.8 ± 0.7) E-6 ph/cm2/s. The estimated photon index above 100 MeV is -1.8 ± 0.3. The highest-energy photon is a 6.8 GeV event which is observed ~1400 seconds after the GBM trigger.
A Swift ToO has been approved for this burst.
The Fermi-LAT point of contact for this burst is Aldana Holzmann Airasca (a.holzmannairasca@unitn.it).
The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.

GCN Circular #42753
V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory)
MASTER-OAFA robotic telescope [1] located in Argentina (OAFA observatory of San Juan National University) was pointed to the LAT GRB251118.86 (trigger No 785190695,10h 40m 19.92s , -34d 34m 33.6s, R=0.173833) errorbox 972 sec after notice time and 28422 sec after trigger time at 2025-11-19 04:25:12 UT, with upper limit up to 19.1 mag. The observations began at zenith distance = 83 deg. The sun altitude is -39.6 deg.
The galactic latitude b = 21 deg., longitude l = 275 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3046739
We obtain a following upper limits.

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

   28452 | 2025-11-19 04:25:12 |         MASTER-OAFA | (10h 40m 39.45s , -34d 39m 40.3s) |   C |    60 | 13.8 |        
   28518 | 2025-11-19 04:26:18 |         MASTER-OAFA | (10h 40m 39.40s , -34d 39m 38.3s) |   C |    60 | 14.7 |        
   28584 | 2025-11-19 04:27:23 |         MASTER-OAFA | (10h 40m 39.38s , -34d 39m 35.5s) |   C |    60 | 15.0 |        
   28649 | 2025-11-19 04:28:29 |         MASTER-OAFA | (10h 40m 39.39s , -34d 39m 32.7s) |   C |    60 | 15.4 |        
   28715 | 2025-11-19 04:29:35 |         MASTER-OAFA | (10h 40m 39.27s , -34d 39m 30.8s) |   C |    60 | 15.7 |        
   28780 | 2025-11-19 04:30:40 |         MASTER-OAFA | (10h 40m 39.19s , -34d 39m 28.4s) |   C |    60 | 16.1 |        
   28846 | 2025-11-19 04:31:46 |         MASTER-OAFA | (10h 40m 39.06s , -34d 39m 25.8s) |   C |    60 | 16.2 |        
   28913 | 2025-11-19 04:32:52 |         MASTER-OAFA | (10h 40m 38.91s , -34d 39m 23.6s) |   C |    60 | 16.5 |        
   28978 | 2025-11-19 04:33:58 |         MASTER-OAFA | (10h 40m 38.80s , -34d 39m 21.9s) |   C |    60 | 16.5 |        
   29044 | 2025-11-19 04:35:03 |         MASTER-OAFA | (10h 40m 38.68s , -34d 39m 19.9s) |   C |    60 | 16.7 |        
   29110 | 2025-11-19 04:36:10 |         MASTER-OAFA | (10h 40m 38.57s , -34d 39m 17.8s) |   C |    60 | 17.0 |        
   29175 | 2025-11-19 04:37:15 |         MASTER-OAFA | (10h 40m 38.40s , -34d 39m 16.0s) |   C |    60 | 17.1 |        
   29241 | 2025-11-19 04:38:20 |         MASTER-OAFA | (10h 40m 38.33s , -34d 39m 13.9s) |   C |    60 | 17.3 |        
   29307 | 2025-11-19 04:39:26 |         MASTER-OAFA | (10h 40m 38.21s , -34d 39m 12.1s) |   C |    60 | 17.3 |        
   29372 | 2025-11-19 04:40:32 |         MASTER-OAFA | (10h 40m 38.07s , -34d 39m 10.1s) |   C |    60 | 17.3 |        
   29438 | 2025-11-19 04:41:38 |         MASTER-OAFA | (10h 40m 37.93s , -34d 39m 08.0s) |   C |    60 | 17.3 |        
   29504 | 2025-11-19 04:42:44 |         MASTER-OAFA | (10h 40m 37.75s , -34d 39m 06.1s) |   C |    60 | 17.6 |        
   29570 | 2025-11-19 04:43:49 |         MASTER-OAFA | (10h 40m 37.59s , -34d 39m 04.2s) |   C |    60 | 17.6 |        
   29635 | 2025-11-19 04:44:55 |         MASTER-OAFA | (10h 40m 37.45s , -34d 39m 02.1s) |   C |    60 | 17.6 |        
   29701 | 2025-11-19 04:46:01 |         MASTER-OAFA | (10h 40m 37.31s , -34d 39m 00.4s) |   C |    60 | 17.9 |        
   29767 | 2025-11-19 04:47:06 |         MASTER-OAFA | (10h 40m 37.14s , -34d 38m 58.3s) |   C |    60 | 17.9 |        
   29832 | 2025-11-19 04:48:12 |         MASTER-OAFA | (10h 40m 36.96s , -34d 38m 56.4s) |   C |    60 | 17.9 |        
   29899 | 2025-11-19 04:49:18 |         MASTER-OAFA | (10h 40m 36.87s , -34d 38m 54.3s) |   C |    60 | 17.9 |        
   29965 | 2025-11-19 04:50:24 |         MASTER-OAFA | (10h 40m 36.75s , -34d 38m 52.3s) |   C |    60 | 18.0 |        
   30030 | 2025-11-19 04:51:30 |         MASTER-OAFA | (10h 40m 36.61s , -34d 38m 50.3s) |   C |    60 | 18.0 |        
   30096 | 2025-11-19 04:52:36 |         MASTER-OAFA | (10h 40m 36.50s , -34d 38m 48.1s) |   C |    60 | 18.1 |        
   30162 | 2025-11-19 04:53:41 |         MASTER-OAFA | (10h 40m 36.37s , -34d 38m 46.0s) |   C |    60 | 18.2 |        
   30227 | 2025-11-19 04:54:47 |         MASTER-OAFA | (10h 40m 36.23s , -34d 38m 44.6s) |   C |    60 | 18.2 |        
   30293 | 2025-11-19 04:55:53 |         MASTER-OAFA | (10h 40m 36.14s , -34d 38m 42.1s) |   C |    60 | 18.3 |        
   30359 | 2025-11-19 04:56:58 |         MASTER-OAFA | (10h 40m 36.02s , -34d 38m 40.1s) |   C |    60 | 18.3 |        
   30424 | 2025-11-19 04:58:04 |         MASTER-OAFA | (10h 40m 35.89s , -34d 38m 38.1s) |   C |    60 | 18.4 |        
   30491 | 2025-11-19 04:59:10 |         MASTER-OAFA | (10h 40m 35.75s , -34d 38m 36.2s) |   C |    60 | 18.5 |        
   30556 | 2025-11-19 05:00:16 |         MASTER-OAFA | (10h 40m 35.66s , -34d 38m 33.8s) |   C |    60 | 18.5 |        
   30621 | 2025-11-19 05:01:21 |         MASTER-OAFA | (10h 40m 35.53s , -34d 38m 31.4s) |   C |    60 | 18.5 |        
   30687 | 2025-11-19 05:02:27 |         MASTER-OAFA | (10h 40m 35.40s , -34d 38m 29.6s) |   C |    60 | 18.6 |        
   30753 | 2025-11-19 05:03:32 |         MASTER-OAFA | (10h 40m 35.26s , -34d 38m 27.7s) |   C |    60 | 18.6 |        
   30818 | 2025-11-19 05:04:38 |         MASTER-OAFA | (10h 40m 35.17s , -34d 38m 25.6s) |   C |    60 | 18.6 |        
   30885 | 2025-11-19 05:05:44 |         MASTER-OAFA | (10h 40m 35.05s , -34d 38m 23.5s) |   C |    60 | 18.7 |        
   30950 | 2025-11-19 05:06:50 |         MASTER-OAFA | (10h 40m 34.89s , -34d 38m 21.4s) |   C |    60 | 18.7 |        
   31016 | 2025-11-19 05:07:55 |         MASTER-OAFA | (10h 40m 34.75s , -34d 38m 19.4s) |   C |    60 | 18.7 |        
   31082 | 2025-11-19 05:09:02 |         MASTER-OAFA | (10h 40m 34.60s , -34d 38m 17.2s) |   C |    60 | 18.7 |        
   31147 | 2025-11-19 05:10:07 |         MASTER-OAFA | (10h 40m 34.49s , -34d 38m 15.4s) |   C |    60 | 18.8 |        
   31213 | 2025-11-19 05:11:13 |         MASTER-OAFA | (10h 40m 34.36s , -34d 38m 13.2s) |   C |    60 | 18.8 |        
   31279 | 2025-11-19 05:12:19 |         MASTER-OAFA | (10h 40m 34.23s , -34d 38m 11.3s) |   C |    60 | 18.8 |        
   31345 | 2025-11-19 05:13:24 |         MASTER-OAFA | (10h 40m 34.10s , -34d 38m 09.0s) |   C |    60 | 18.8 |        
   31410 | 2025-11-19 05:14:30 |         MASTER-OAFA | (10h 40m 33.98s , -34d 38m 07.1s) |   C |    60 | 18.9 |        
   31476 | 2025-11-19 05:15:36 |         MASTER-OAFA | (10h 40m 33.86s , -34d 38m 04.6s) |   C |    60 | 18.9 |        
   31542 | 2025-11-19 05:16:41 |         MASTER-OAFA | (10h 40m 33.76s , -34d 38m 02.4s) |   C |    60 | 18.9 |        
   31607 | 2025-11-19 05:17:47 |         MASTER-OAFA | (10h 40m 33.66s , -34d 38m 00.3s) |   C |    60 | 18.9 |        
   31673 | 2025-11-19 05:18:52 |         MASTER-OAFA | (10h 40m 33.53s , -34d 37m 58.3s) |   C |    60 | 18.9 |        
   31738 | 2025-11-19 05:19:58 |         MASTER-OAFA | (10h 40m 33.38s , -34d 37m 56.0s) |   C |    60 | 18.9 |        
   31804 | 2025-11-19 05:21:03 |         MASTER-OAFA | (10h 40m 33.26s , -34d 37m 53.7s) |   C |    60 | 18.9 |        
   31870 | 2025-11-19 05:22:10 |         MASTER-OAFA | (10h 40m 33.13s , -34d 37m 51.8s) |   C |    60 | 18.9 |        
   31936 | 2025-11-19 05:23:16 |         MASTER-OAFA | (10h 40m 33.01s , -34d 37m 49.6s) |   C |    60 | 18.9 |        
   32002 | 2025-11-19 05:24:21 |         MASTER-OAFA | (10h 40m 32.90s , -34d 37m 47.5s) |   C |    60 | 18.9 |        
   32068 | 2025-11-19 05:25:27 |         MASTER-OAFA | (10h 40m 32.77s , -34d 37m 45.1s) |   C |    60 | 19.0 |        
   32133 | 2025-11-19 05:26:33 |         MASTER-OAFA | (10h 40m 32.64s , -34d 37m 42.8s) |   C |    60 | 18.9 |        
   32198 | 2025-11-19 05:27:38 |         MASTER-OAFA | (10h 40m 32.50s , -34d 37m 40.9s) |   C |    60 | 18.9 |        
   32265 | 2025-11-19 05:28:44 |         MASTER-OAFA | (10h 40m 32.41s , -34d 37m 38.8s) |   C |    60 | 18.9 |        
   32330 | 2025-11-19 05:29:50 |         MASTER-OAFA | (10h 40m 32.29s , -34d 37m 36.8s) |   C |    60 | 19.0 |        
   32396 | 2025-11-19 05:30:55 |         MASTER-OAFA | (10h 40m 32.17s , -34d 37m 34.7s) |   C |    60 | 19.0 |        
   32462 | 2025-11-19 05:32:01 |         MASTER-OAFA | (10h 40m 32.05s , -34d 37m 32.6s) |   C |    60 | 19.0 |        
   32527 | 2025-11-19 05:33:07 |         MASTER-OAFA | (10h 40m 31.94s , -34d 37m 30.3s) |   C |    60 | 19.0 |        
   32592 | 2025-11-19 05:34:12 |         MASTER-OAFA | (10h 40m 31.81s , -34d 37m 28.3s) |   C |    60 | 19.0 |        
   32659 | 2025-11-19 05:35:18 |         MASTER-OAFA | (10h 40m 31.72s , -34d 37m 26.0s) |   C |    60 | 19.0 |        
   32724 | 2025-11-19 05:36:24 |         MASTER-OAFA | (10h 40m 31.62s , -34d 37m 24.0s) |   C |    60 | 19.0 |        
   32790 | 2025-11-19 05:37:29 |         MASTER-OAFA | (10h 40m 31.49s , -34d 37m 22.0s) |   C |    60 | 19.0 |        
   32856 | 2025-11-19 05:38:36 |         MASTER-OAFA | (10h 40m 31.39s , -34d 37m 19.8s) |   C |    60 | 19.0 |        
   32922 | 2025-11-19 05:39:41 |         MASTER-OAFA | (10h 40m 31.28s , -34d 37m 17.6s) |   C |    60 | 19.0 |        
   32987 | 2025-11-19 05:40:47 |         MASTER-OAFA | (10h 40m 31.23s , -34d 37m 15.6s) |   C |    60 | 19.0 |        
   33053 | 2025-11-19 05:41:53 |         MASTER-OAFA | (10h 40m 31.08s , -34d 37m 13.4s) |   C |    60 | 19.1 |        
   33118 | 2025-11-19 05:42:58 |         MASTER-OAFA | (10h 40m 31.04s , -34d 37m 11.1s) |   C |    60 | 19.0 |        
   33184 | 2025-11-19 05:44:03 |         MASTER-OAFA | (10h 40m 30.92s , -34d 37m 09.5s) |   C |    60 | 19.0 |        
   33250 | 2025-11-19 05:45:10 |         MASTER-OAFA | (10h 40m 30.85s , -34d 37m 07.0s) |   C |    60 | 19.0 |        
   33316 | 2025-11-19 05:46:15 |         MASTER-OAFA | (10h 40m 30.75s , -34d 37m 05.0s) |   C |    60 | 19.0 |        
   33381 | 2025-11-19 05:47:21 |         MASTER-OAFA | (10h 40m 30.69s , -34d 37m 03.0s) |   C |    60 | 19.0 |        
   33448 | 2025-11-19 05:48:28 |         MASTER-OAFA | (10h 40m 30.59s , -34d 37m 00.4s) |   C |    60 | 19.1 |        
   33513 | 2025-11-19 05:49:33 |         MASTER-OAFA | (10h 40m 30.50s , -34d 36m 58.5s) |   C |    60 | 19.0 |        
   33579 | 2025-11-19 05:50:38 |         MASTER-OAFA | (10h 40m 30.45s , -34d 36m 56.3s) |   C |    60 | 19.1 |        
   33645 | 2025-11-19 05:51:44 |         MASTER-OAFA | (10h 40m 30.39s , -34d 36m 54.0s) |   C |    60 | 19.0 |        
   33710 | 2025-11-19 05:52:50 |         MASTER-OAFA | (10h 40m 30.29s , -34d 36m 51.8s) |   C |    60 | 19.0 |        
   33776 | 2025-11-19 05:53:56 |         MASTER-OAFA | (10h 40m 30.20s , -34d 36m 50.0s) |   C |    60 | 19.0 |        
   33842 | 2025-11-19 05:55:02 |         MASTER-OAFA | (10h 40m 30.14s , -34d 36m 47.5s) |   C |    60 | 19.0 |        
   33908 | 2025-11-19 05:56:08 |         MASTER-OAFA | (10h 40m 30.05s , -34d 36m 45.1s) |   C |    60 | 19.1 |        
   33973 | 2025-11-19 05:57:13 |         MASTER-OAFA | (10h 40m 29.97s , -34d 36m 43.0s) |   C |    60 | 19.0 |        
   34039 | 2025-11-19 05:58:19 |         MASTER-OAFA | (10h 40m 29.87s , -34d 36m 40.9s) |   C |    60 | 19.0 |        
   34104 | 2025-11-19 05:59:24 |         MASTER-OAFA | (10h 40m 29.79s , -34d 36m 38.4s) |   C |    60 | 19.0 |        
   34169 | 2025-11-19 06:00:29 |         MASTER-OAFA | (10h 40m 29.72s , -34d 36m 36.7s) |   C |    60 | 19.0 |        
   34236 | 2025-11-19 06:01:35 |         MASTER-OAFA | (10h 40m 29.62s , -34d 36m 34.4s) |   C |    60 | 19.0 |        
   34302 | 2025-11-19 06:02:41 |         MASTER-OAFA | (10h 40m 29.57s , -34d 36m 32.4s) |   C |    60 | 19.0 |        
   34367 | 2025-11-19 06:03:47 |         MASTER-OAFA | (10h 40m 29.51s , -34d 36m 29.9s) |   C |    60 | 19.0 |        
   34433 | 2025-11-19 06:04:53 |         MASTER-OAFA | (10h 40m 29.42s , -34d 36m 27.6s) |   C |    60 | 19.0 |        
   34499 | 2025-11-19 06:05:58 |         MASTER-OAFA | (10h 40m 29.36s , -34d 36m 25.3s) |   C |    60 | 19.0 |

Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
[1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html

GCN Circular #42774
G. Waratkar (Caltech) and B. Grefenstette (Caltech) report on behalf of the NuSTAR Search for INteresting Gamma-ray Signals (SINGS) working group:
The NuSTAR SINGS working group reports the detection of prompt emission from the long-duration GRB 251118A in both the NuSTAR CsI anti-coincidence shields. This GRB was identified through a blind search using the CsI shield rates. Details of the search algorithm will be described in a future paper.
The NuSTAR SINGS algorithm triggered at 2025-11-18 20:32:21.000 (with a resolution ~5-seconds). This is consistent with the detections of GRB 251118A by Fermi/GBM (Fermi GBM Team, GCN Circ. 42743) and Fermi/LAT (Gupta et al., GCN Circ. 42752).
The NuSTAR CsI shield data are recorded at 1 Hz. We do not detect the first two bursts as seen in the Fermi/GBM lightcurve (GCN Circ. 42743) and detect the third bright burst. The burst appears to be composed of one bright peak lasting for ~9-s. The peak count rate is ~3000-cps over a baseline rate of ~1,000-cps during this time period. We do not see any evidence in the signal above 100 keV in the CdZnTe detectors.
The Fermi/LAT localization (GCN Circ. 42752) at RA = 160.08, Dec = -34.58 implies an offset from the NuSTAR boresight of 140-deg and an offset from the geocenter of 99-deg.
Lightcurves and analysis for this GRB can be found here: https://nustarsoc.caltech.edu/NuSTAR_Public/grbs/reports/2025/251118A
Information on NuSTAR SINGS can be found here: https://nustarsoc.caltech.edu/NuSTAR_Public/grbs/
NuSTAR is a NASA Small Explorer mission led by Caltech and managed by JPL for NASA's Science Mission Directorate in Washington.
GCN Circular #42779
Yang-Zhao Ren, Chen-Wei Wang, Chao Zheng, Shao-Lin Xiong (IHEP) report on behalf of GECAM team:
GECAM-B was triggered in-flight by a long burst, GRB 251118A, at 2025-11-18T20:31:30.089 UTC (denoted as T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #42743), Fermi/LAT (Gupta et. al., GCN #42752), and NuSTAR (Waratkar et. al., GCN #42774).
According to the GECAM-B light curves in about 40-6000 keV, this burst mainly consists of multiple pulses with a duration (T90) of 46.2 +0.2/-0.3 s.
The GECAM-B light curve can be found here: https://www.bursthub.cn//admin/static/gecambgrb251118A.png
The time-averaged spectrum from T0-1.9 s to T0+71.0 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.54 +0.09/-0.09 and the cutoff energy, parameterized as Epeak, is 99.8 +4.4/-4.5 keV. The event fluence (10-1000 keV) in this time interval is (1.01 +0.04/-0.04)E-04 erg/cm^2. The 'Amati' relation diagram of GRB 251118A is shown at: https://www.bursthub.cn//admin/static/gecambgrb251118A_amati.png
Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission originally consists of two micro-satellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS).
GCN Circular #42782
J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-OAR), D.N. Burrows (PSU), S. Lanava (PSU), S. Dichiara (PSU) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the Fermi/LAT-detected burst GRB 251118A. We searched for X-ray sources in 3.0 ks of Photon Counting (PC) mode data. The total exposure at the position of the afterglow (see below) is 5.4 ks, obtained between T0+31.3 ks and T0+108.8 ks.
Two uncatalogued X-ray sources are detected, of which one ("Source 1") is above the RASS 3-sigma upper limit at this position, and is therefore likely the GRB afterglow. Using 3939 s of PC mode data and 7 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 160.00418, -34.52259 which is equivalent to:
```
RA (J2000): 10h 40m 01.00s
Dec(J2000): -34d 31' 21.3"
```
with an uncertainty of 2.0 arcsec (radius, 90% confidence). This position is 5.0 arcmin from the Fermi/LAT position.
The light curve can be modelled with a power-law decay with a decay index of alpha=1.08 (+0.18, -0.16).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.73 (+0.16, -0.15). The best-fitting absorption column is 2.2 (+0.7, -0.6) x 10^21 cm^-2, in excess of the Galactic value of 8.3 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.1 x 10^-11 (5.2 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     2.2 (+0.7, -0.6) x 10^21 cm^-2
Galactic foreground: 8.3 x 10^20 cm^-2
Excess significance: 3.9 sigma
Photon index:	     1.73 (+0.16, -0.15)
```
The results of the XRT-team automatic analysis are available at https://www.swift.ac.uk/xrt_products/00021890. The results of the full analysis of the XRT observations are available at https://www.swift.ac.uk/ToO_GRBs/00021890.
This circular is an official product of the Swift-XRT team.
GCN Circular #42783
Eva Palafox (INAOE) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team:
"At 20:31:30.09 UT on 18 November 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251118A (trigger 785190695/251118855), which was also detected by Fermi-LAT (R. Gupta et al. 2025, GCN 42752), Swift/XRT (J.P. Osborne et al. 2025, GCN 42782), GECAM-B (Yang-Zhao Ren et al., 2025, GCN 42779) and NuSTAR (G. Waratkar et al. 2025, GCN 42774). The Fermi GBM final real-time localization (GCN 42743) is consistent with the Fermi-LAT position.
The angle from the Fermi LAT boresight is 69 degrees.
The GBM light curve consists of a faint emission episode, followed by very bright emission episodes, with a total duration (T90) of about 46.6 s (50-300 keV). The time-averaged spectrum from T0-2.8 to T0+87.3 s is best fit by a Comptonized function with Epeak = 149.3 +/- 2.0 keV, and alpha = -1.40 +/- 0.01. A Band function fits equally well with Epeak = 134.0 +/- 2.7, alpha = -1.36 +/- 0.01, and beta = -2.56 +/- 0.06.
The event fluence (10-1000 keV) in this time interval is (1.03 +/- 0.01)E-04 erg/cm^2. The 1-sec peak photon flux measured starting from T0+52 s in the 10-1000 keV band is 96 +/- 0.7 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/"
GCN Circular #42784
C.C. Cheung, R. Woolf, M. Kerr, J.E. Grove (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge, D. Kocevski (MSFC), and M.S. Briggs (UAH) report:
The Glowbug gamma-ray telescope [1,2,3], operating on the International Space Station, reports the detection of GRB 251118A, which was also detected by Fermi/GBM (GCN 42743, 42745, 42783), Fermi/LAT (GCN 42752), NuSTAR (GCN 42774), and GECAM-B (GCN 42779).
Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2025-11-18 20:31:43.57 with a duration of 47.1 s and a total significance of over 360 sigma. The light curve comprises two peaks at ~T0+1.5s and +37s, matching the two brightest peaks in the Fermi/GBM and GECAM-B lightcurves. The initial faint emission at the GBM trigger time (20:31:30) may be present in the Glowbug light curve at low significance. The GRB was detected despite the elevated background due to Glowbug being in and exiting the Southern polar region at the time of the burst. Note that data throughout the burst interval suffered from deadtime in various detectors.
The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS.
Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard the Department of Defense Space Test Program’s STP-H9 to the ISS and operated until 2024 April when it was put in safe storage on orbit. Glowbug was removed from storage and resumed operation on 2025 September 12.
```
[1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959
[2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O
[3] Woolf, R.S. et al. 2024, Proc. SPIE, 13151, id. 1315108
```
Distribution Statement A: Approved for public release. Distribution is unlimited.
GCN Circular #42786
M. H. Siegel (PSU) reports on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 251118A 31.3 ks after the Fermi trigger (GCN Circ. 42743). A fading source consistent with the XRT position (Osbourne et al., GCN Circ. 42782) is detected in the UVOT exposures.
The preliminary UVOT position is:
```
    RA  (J2000) =  10:14:01.01 = 160.00422 (deg.)
    Dec (J2000) = -34:31:21.1  = -34.52254 (deg.)
```
with an estimated uncertainty of 0.42 arc sec. (radius, 90% confidence).
Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)           Mag
white            31521        52651          885      18.79+/-0.05
white           108251       159027         1113      20.11+/-0.10
v                31678        42929          845      18.60+/-0.19
v               108564       147691          662            >19.73
u                31363        52627         2489      18.41+/-0.05
u               107942       158555         1113      19.61+/-0.15
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.057 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #43013
V. Panteleeva, D. Frederiks, A. Lysenko, A. Ridnaia, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report:
The long-duration GRB 251118A (Fermi-GBM detection: The Fermi GBM team, GCN 42743; Palafox and Meegan, GCN 42783; BALROG localization: Preis and Greiner, GCN 42745; Fermi-LAT detection: Gupta and Khalil, GCN 42752; GECAM-B detection: Ren et al., GCN 42779; Glowbug detection: Cheung et al., GCN 42784) triggered Konus-Wind at T0=73904.449 s UT (20:31:44.449).
The burst light curve starts, at ~T0-20.5 s, with a short soft initial pulse (precursor) which had a duration of about 25.8 s. The precursor is followed, starting at ~T0+32 s, by the main episode, lasting for ~25 s. The total duration of the burst is ~48 s. The emission in the main episode is seen up to ~3 MeV.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB251118_T73904/
As observed by Konus-Wind, the burst had the total fluence of 1.07(-0.03,+0.03)x10^-4 erg/cm2, and the 64-ms peak flux, measured from T0+35.776 s, of 2.03(-0.15,+0.15)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the initial pulse (measured from T0 to T0+8.448 s) is best described in the 20 keV - 10 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -1.94(-0.03,+0.12) and Ep < 41 keV (chi2 = 89/85 dof). Fitting this spectrum by a GRB (Band) model results in the same estimates of alpha and Ep, and gives only an upper limit on the high energy photon index beta of -2.8 (chi2 = 89/84 dof).
The time-averaged spectrum of the main episode (measured from T0+33.024 to T0+65.536 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -1.29(-0.03,+0.04), the high energy photon index beta = -2.56(-0.08,+0.07), the peak energy Ep = 154(-5,+5) keV (chi2 = 110/97 dof).
The spectrum near the maximum count rate (measured from T0+33.024 to T0+36.608 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.74(-0.05,+0.06), the high energy photon index beta = -2.53(-0.10,+0.08), the peak energy Ep = 251(-12,+12) keV (chi2 = 68/69 dof).
All the quoted errors are at the 68% confidence level. All the quoted values are preliminary.
GCN Circular #44680
Nicholas Kirschner (a), Daniel Shy (b), C.C. Cheung (b), Bernard Phlips (b), Michael Streicher (c), James Mason (c), Douglas M. Groves (c), Feng Zhang (c), and Willy Kaye (c)
(a) National Research Council Research Associate resident at the U.S. Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375 (b) U.S. Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375 (c) H3D, Inc., 812 Avis Dr., Ann Arbor, MI 48108, USA
The cadmium zinc TElluride Radiation Imager (TERI) gamma-ray telescope [1], operating on the International Space Station, reports the detection of GRB 251118A, which was also detected by Glowbug (GCN 42784), Fermi GBM (GCN 42743, 42745, 42783), Fermi LAT (GCN 42752), NuSTAR (GCN 42774), and GECAM-B (GCN 42779). Using 1 Hz binning, and adopting T0 = 2025-11-18T20:31:43.57Z, we observe two peaks at T0+4.5s and 40.5s.
The analysis results presented here are preliminary and currently lack a detailed response function.
TERI is an Office of Naval Research funded technology demonstrator for large-volume pixelated CdZnTe detectors developed, built, and operated by the U.S. Naval Research Laboratory (NRL) in conjunction with H3D, Inc. The pixelated CdZnTe detectors have an energy range of 40 keV to 3 MeV per pixel. It was launched on 2025 April 21 aboard the Department of Defense Space Test Program STP-H10 to the ISS. On the ISS, it is located on the SOX external payload facility on the Columbus module. Analysis of TERI data at NRL is supported by the Office of Naval Research 6.1.
[1] Shy, Daniel, et al. "Development of the cadmium zinc TElluride Radiation Imager." Journal of Astronomical Telescopes, Instruments, and Systems 10.4 (2024): 044009-044009 (arXiv:2408.04559).
Distribution Statement A: Approved for public release. Distribution is unlimited.

Back to JG's homepage

Jochen Greiner, last update: 21-May-2026 [Disclaimer]