Gamma-ray Burst 260223A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 23 Feb 26 04:11:48 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      58
TRIGGER_NUM:     793512674
GRB_RA:          113.317d {+07h 33m 16s} (J2000),
                 113.577d {+07h 34m 18s} (current),
                 112.819d {+07h 31m 17s} (1950)
GRB_DEC:         -29.267d {-29d 16' 00"} (J2000),
                 -29.325d {-29d 19' 28"} (current),
                 -29.158d {-29d 09' 26"} (1950)
GRB_ERROR:       13.02 [deg radius, statistical plus systematic]
GRB_INTEN:       123 [cnts/sec]
DATA_SIGNIF:     12.80 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        21094 TJD;    54 DOY;   26/02/23
GRB_TIME:        15069.81 SOD {04:11:09.81} UT
GRB_PHI:         184.00 [deg]
GRB_THETA:        35.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      1.21
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      98%  GRB
2nd_MOST_LIKELY:   1%  Generic SGR
DETECTORS:       0,0,0, 0,0,0, 0,1,0, 1,1,0, 0,0,
SUN_POSTN:       336.41d {+22h 25m 39s}   -9.84d {-09d 50' 22"}
SUN_DIST:        123.11 [deg]   Sun_angle= -9.1 [hr] (East of Sun)
MOON_POSTN:       42.85d {+02h 51m 23s}  +21.56d {+21d 33' 18"}
MOON_DIST:        84.97 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      243.53, -4.70 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      122.57,-50.10 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260223174/quicklook/glg_lc_medres34_bn260223174.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 246.10,-3.10 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 23 Feb 26 04:11:54 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      69
TRIGGER_NUM:     793512674
GRB_RA:          106.717d {+07h 06m 52s} (J2000),
                 106.970d {+07h 07m 53s} (current),
                 106.232d {+07h 04m 56s} (1950)
GRB_DEC:         -30.267d {-30d 16' 00"} (J2000),
                 -30.309d {-30d 18' 31"} (current),
                 -30.188d {-30d 11' 15"} (1950)
GRB_ERROR:       10.58 [deg radius, statistical plus systematic]
GRB_INTEN:       177 [cnts/sec]
DATA_SIGNIF:     19.00 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        21094 TJD;    54 DOY;   26/02/23
GRB_TIME:        15069.81 SOD {04:11:09.81} UT
GRB_PHI:         190.00 [deg]
GRB_THETA:        30.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      1.49
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      98%  GRB
2nd_MOST_LIKELY:   1%  Generic SGR
DETECTORS:       0,0,0, 0,0,0, 0,1,0, 1,1,0, 0,0,
SUN_POSTN:       336.41d {+22h 25m 39s}   -9.84d {-09d 50' 21"}
SUN_DIST:        117.83 [deg]   Sun_angle= -8.7 [hr] (East of Sun)
MOON_POSTN:       42.85d {+02h 51m 23s}  +21.56d {+21d 33' 19"}
MOON_DIST:        80.50 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      241.80,-10.26 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      113.98,-52.32 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260223174/quicklook/glg_lc_medres34_bn260223174.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 246.10,-3.10 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 23 Feb 26 04:11:39 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      46
TRIGGER_NUM:     793512674
GRB_RA:          115.267d {+07h 41m 04s} (J2000),
                 115.543d {+07h 42m 10s} (current),
                 114.738d {+07h 38m 57s} (1950)
GRB_DEC:         -24.033d {-24d 01' 59"} (J2000),
                 -24.096d {-24d 05' 44"} (current),
                 -23.916d {-23d 54' 55"} (1950)
GRB_ERROR:       29.48 [deg radius, statistical plus systematic]
GRB_INTEN:       63 [cnts/sec]
DATA_SIGNIF:     5.60 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        21094 TJD;    54 DOY;   26/02/23
GRB_TIME:        15069.81 SOD {04:11:09.81} UT
GRB_PHI:         188.00 [deg]
GRB_THETA:        40.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      1.05
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      97%  GRB
2nd_MOST_LIKELY:   1%  Generic SGR
DETECTORS:       0,0,0, 0,0,0, 0,1,0, 1,1,0, 0,0,
SUN_POSTN:       336.41d {+22h 25m 39s}   -9.84d {-09d 50' 22"}
SUN_DIST:        127.62 [deg]   Sun_angle= -9.3 [hr] (East of Sun)
MOON_POSTN:       42.84d {+02h 51m 23s}  +21.55d {+21d 33' 16"}
MOON_DIST:        84.12 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      239.80, -0.63 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      123.20,-44.60 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260223174/quicklook/glg_lc_medres34_bn260223174.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 246.10,-3.10 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 23 Feb 26 04:11:57 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      57
TRIGGER_NUM:     793512674
GRB_RA:          105.840d {+07h 03m 22s} (J2000),
                 106.085d {+07h 04m 20s} (current),
                 105.371d {+07h 01m 29s} (1950)
GRB_DEC:         -32.620d {-32d 37' 11"} (J2000),
                 -32.660d {-32d 39' 35"} (current),
                 -32.545d {-32d 32' 41"} (1950)
GRB_ERROR:       6.85 [deg radius, statistical only]
DATA_SIGNIF:     13.00 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        21094 TJD;    54 DOY;   26/02/23
GRB_TIME:        15069.81 SOD {04:11:09.81} UT
GRB_PHI:         187.00 [deg]
GRB_THETA:        28.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4173 (Gnd S/W Version number)
SUN_POSTN:       336.41d {+22h 25m 39s}   -9.84d {-09d 50' 21"}
SUN_DIST:        115.93 [deg]   Sun_angle= -8.6 [hr] (East of Sun)
MOON_POSTN:       42.85d {+02h 51m 23s}  +21.56d {+21d 33' 20"}
MOON_DIST:        81.12 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      243.65,-11.94 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      113.49,-54.78 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260223174/quicklook/glg_lc_medres34_bn260223174.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_793512674.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        In the LAT Field-of-view.  
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:     Mon 23 Feb 26 04:12:03 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      72
TRIGGER_NUM:     793512674
GRB_RA:          113.817d {+07h 35m 16s} (J2000),
                 114.077d {+07h 36m 18s} (current),
                 113.319d {+07h 33m 17s} (1950)
GRB_DEC:         -29.333d {-29d 19' 59"} (J2000),
                 -29.392d {-29d 23' 32"} (current),
                 -29.222d {-29d 13' 18"} (1950)
GRB_ERROR:       6.73 [deg radius, statistical plus systematic]
GRB_INTEN:       489 [cnts/sec]
DATA_SIGNIF:     36.10 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        21094 TJD;    54 DOY;   26/02/23
GRB_TIME:        15069.81 SOD {04:11:09.81} UT
GRB_PHI:         184.00 [deg]
GRB_THETA:        35.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      1.00
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      98%  GRB
2nd_MOST_LIKELY:   1%  Generic SGR
DETECTORS:       0,0,0, 0,0,0, 0,1,0, 1,1,0, 0,0,
SUN_POSTN:       336.41d {+22h 25m 39s}   -9.84d {-09d 50' 21"}
SUN_DIST:        123.42 [deg]   Sun_angle= -9.2 [hr] (East of Sun)
MOON_POSTN:       42.85d {+02h 51m 24s}  +21.56d {+21d 33' 21"}
MOON_DIST:        85.39 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      243.80, -4.35 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      123.25,-50.06 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260223174/quicklook/glg_lc_medres34_bn260223174.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 246.10,-3.10 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 23 Feb 26 04:13:02 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      2
TRIGGER_NUM:     793512674
GRB_RA:          110.220d {+07h 20m 53s} (J2000),
                 110.478d {+07h 21m 55s} (current),
                 109.726d {+07h 18m 54s} (1950)
GRB_DEC:         -29.330d {-29d 19' 47"} (J2000),
                 -29.381d {-29d 22' 49"} (current),
                 -29.235d {-29d 14' 05"} (1950)
GRB_ERROR:       3.66 [deg radius, statistical only]
DATA_SIGNIF:     24.20 [sigma]
DATA_INTERVAL:   14.336 [sec]
GRB_DATE:        21094 TJD;    54 DOY;   26/02/23
GRB_TIME:        15069.81 SOD {04:11:09.81} UT
GRB_PHI:         187.00 [deg]
GRB_THETA:        33.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       336.41d {+22h 25m 39s}   -9.84d {-09d 50' 20"}
SUN_DIST:        120.88 [deg]   Sun_angle= -8.9 [hr] (East of Sun)
MOON_POSTN:       42.86d {+02h 51m 26s}  +21.56d {+21d 33' 32"}
MOON_DIST:        82.63 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      242.32, -7.12 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      118.47,-50.79 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260223174/quicklook/glg_lc_medres34_bn260223174.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_793512674.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        In the LAT Field-of-view.  
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:     Mon 23 Feb 26 04:12:43 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      0
TRIGGER_NUM:     793512674
GRB_RA:          110.090d {+07h 20m 22s} (J2000),
                 110.348d {+07h 21m 24s} (current),
                 109.596d {+07h 18m 23s} (1950)
GRB_DEC:         -29.310d {-29d 18' 35"} (J2000),
                 -29.360d {-29d 21' 36"} (current),
                 -29.215d {-29d 12' 55"} (1950)
GRB_ERROR:       6.35 [deg radius, statistical only]
DATA_SIGNIF:     14.10 [sigma]
DATA_INTERVAL:   8.192 [sec]
GRB_DATE:        21094 TJD;    54 DOY;   26/02/23
GRB_TIME:        15069.81 SOD {04:11:09.81} UT
GRB_PHI:         187.00 [deg]
GRB_THETA:        33.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       336.41d {+22h 25m 39s}   -9.84d {-09d 50' 21"}
SUN_DIST:        120.80 [deg]   Sun_angle= -8.9 [hr] (East of Sun)
MOON_POSTN:       42.86d {+02h 51m 25s}  +21.56d {+21d 33' 29"}
MOON_DIST:        82.52 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      242.25, -7.21 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      118.28,-50.80 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260223174/quicklook/glg_lc_medres34_bn260223174.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_793512674.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        In the LAT Field-of-view.  
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:     Mon 23 Feb 26 04:12:53 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      1
TRIGGER_NUM:     793512674
GRB_RA:          110.150d {+07h 20m 36s} (J2000),
                 110.408d {+07h 21m 38s} (current),
                 109.656d {+07h 18m 37s} (1950)
GRB_DEC:         -29.320d {-29d 19' 11"} (J2000),
                 -29.370d {-29d 22' 13"} (current),
                 -29.225d {-29d 13' 30"} (1950)
GRB_ERROR:       5.28 [deg radius, statistical only]
DATA_SIGNIF:     17.70 [sigma]
DATA_INTERVAL:   11.264 [sec]
GRB_DATE:        21094 TJD;    54 DOY;   26/02/23
GRB_TIME:        15069.81 SOD {04:11:09.81} UT
GRB_PHI:         187.00 [deg]
GRB_THETA:        33.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       336.41d {+22h 25m 39s}   -9.84d {-09d 50' 21"}
SUN_DIST:        120.84 [deg]   Sun_angle= -8.9 [hr] (East of Sun)
MOON_POSTN:       42.86d {+02h 51m 26s}  +21.56d {+21d 33' 31"}
MOON_DIST:        82.57 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      242.28, -7.17 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      118.37,-50.79 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260223174/quicklook/glg_lc_medres34_bn260223174.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_793512674.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        In the LAT Field-of-view.  
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:     Mon 23 Feb 26 04:13:12 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      3
TRIGGER_NUM:     793512674
GRB_RA:          110.300d {+07h 21m 12s} (J2000),
                 110.558d {+07h 22m 14s} (current),
                 109.806d {+07h 19m 14s} (1950)
GRB_DEC:         -29.350d {-29d 21' 00"} (J2000),
                 -29.401d {-29d 24' 02"} (current),
                 -29.255d {-29d 15' 15"} (1950)
GRB_ERROR:       2.99 [deg radius, statistical only]
DATA_SIGNIF:     32.70 [sigma]
DATA_INTERVAL:   18.432 [sec]
GRB_DATE:        21094 TJD;    54 DOY;   26/02/23
GRB_TIME:        15069.81 SOD {04:11:09.81} UT
GRB_PHI:         187.00 [deg]
GRB_THETA:        33.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       336.41d {+22h 25m 39s}   -9.84d {-09d 50' 20"}
SUN_DIST:        120.93 [deg]   Sun_angle= -8.9 [hr] (East of Sun)
MOON_POSTN:       42.86d {+02h 51m 26s}  +21.56d {+21d 33' 34"}
MOON_DIST:        82.70 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      242.37, -7.07 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      118.58,-50.79 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260223174/quicklook/glg_lc_medres34_bn260223174.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_793512674.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        In the LAT Field-of-view.  
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:     Mon 23 Feb 26 04:13:22 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      4
TRIGGER_NUM:     793512674
GRB_RA:          110.340d {+07h 21m 22s} (J2000),
                 110.598d {+07h 22m 24s} (current),
                 109.846d {+07h 19m 23s} (1950)
GRB_DEC:         -29.350d {-29d 21' 00"} (J2000),
                 -29.401d {-29d 24' 02"} (current),
                 -29.254d {-29d 15' 15"} (1950)
GRB_ERROR:       1.95 [deg radius, statistical only]
DATA_SIGNIF:     35.00 [sigma]
DATA_INTERVAL:   20.480 [sec]
GRB_DATE:        21094 TJD;    54 DOY;   26/02/23
GRB_TIME:        15069.81 SOD {04:11:09.81} UT
GRB_PHI:         187.00 [deg]
GRB_THETA:        33.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       336.41d {+22h 25m 39s}   -9.84d {-09d 50' 20"}
SUN_DIST:        120.96 [deg]   Sun_angle= -8.9 [hr] (East of Sun)
MOON_POSTN:       42.86d {+02h 51m 27s}  +21.56d {+21d 33' 36"}
MOON_DIST:        82.73 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      242.38, -7.04 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      118.64,-50.79 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260223174/quicklook/glg_lc_medres34_bn260223174.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_793512674.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        In the LAT Field-of-view.  
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:     Mon 23 Feb 26 04:19:07 UT
NOTICE_TYPE:     Fermi-GBM Final Position
RECORD_NUM:      0
TRIGGER_NUM:     793512674
GRB_RA:          110.500d {+07h 22m 00s} (J2000),
                 110.758d {+07h 23m 02s} (current),
                 110.006d {+07h 20m 01s} (1950)
GRB_DEC:         -29.380d {-29d 22' 47"} (J2000),
                 -29.431d {-29d 25' 52"} (current),
                 -29.284d {-29d 17' 00"} (1950)
GRB_ERROR:       1.70 [deg radius, statistical only]
GRB_DATE:        21094 TJD;    54 DOY;   26/02/23
GRB_TIME:        15069.81 SOD {04:11:09.81} UT
GRB_PHI:         187.00 [deg]
GRB_THETA:        33.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       336.42d {+22h 25m 40s}   -9.84d {-09d 50' 15"}
SUN_DIST:        121.05 [deg]   Sun_angle= -9.0 [hr] (East of Sun)
MOON_POSTN:       42.92d {+02h 51m 41s}  +21.58d {+21d 34' 43"}
MOON_DIST:        82.83 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      242.47, -6.93 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      118.86,-50.79 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260223174/quicklook/glg_lc_medres34_bn260223174.gif
LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260223174/quicklook/glg_locplot_all_bn260223174.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:        In the LAT Field-of-view.  
COMMENTS:        This is likely a Long GRB.

GCN Circular #43808
The Fermi GBM team reports the detection of a likely LONG GRB
At 04:11:09 UT on 23 Feb 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260223A (trigger 793512674.810552 / 260223174).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 110.5, Dec = -29.4 (J2000 degrees, equivalent to J2000 07h 21m, -29d 23'), with a statistical uncertainty of 1.7 degrees.
The angle from the Fermi LAT boresight is 33.0 degrees.
The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260223174/quicklook/glg_skymap_all_bn260223174.png
The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260223174/quicklook/glg_healpix_all_bn260223174.fit
The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260223174/quicklook/glg_lc_medres34_bn260223174.gif

GCN Circular #43809
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) started inspect of the Fermi GRB 260223A ( Fermi GBM team, GCN 43808) errorbox 123 sec after notice time and 154 sec after trigger time at 2026-02-23 04:13:44 UT, with upper limit up to 19.8 mag. The observations began at zenith distance = 32 deg. The sun altitude is -48.2 deg.
The galactic latitude b = -7 deg., longitude l = 243 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3152151
We obtain a following upper limits.

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

     170 | 2026-02-23 04:13:44 |         MASTER-OAFA | (07h 21m 14.73s , -29d 00m 58.9s) |   C |    30 | 19.3 |        
     210 | 2026-02-23 04:14:20 |         MASTER-OAFA | (07h 21m 14.73s , -29d 00m 58.0s) |   C |    40 | 19.5 |        
     262 | 2026-02-23 04:15:07 |         MASTER-OAFA | (07h 21m 14.77s , -29d 00m 57.4s) |   C |    50 | 19.6 |        
     324 | 2026-02-23 04:16:03 |         MASTER-OAFA | (07h 21m 14.79s , -29d 00m 56.9s) |   C |    60 | 18.9 |        
     395 | 2026-02-23 04:17:09 |         MASTER-OAFA | (07h 21m 14.83s , -29d 00m 56.3s) |   C |    70 | 19.8 |        
     603 | 2026-02-23 04:20:17 |         MASTER-OAFA | (07h 22m 38.12s , -29d 04m 33.0s) |   C |   110 | 19.3 |        
     730 | 2026-02-23 04:22:15 |         MASTER-OAFA | (07h 22m 38.17s , -29d 04m 33.2s) |   C |   130 | 19.4 |        
     882 | 2026-02-23 04:24:31 |         MASTER-OAFA | (07h 22m 38.28s , -29d 04m 33.1s) |   C |   160 | 19.5 |        
     998 | 2026-02-23 04:27:17 |         MASTER-OAFA | (07h 22m 38.38s , -29d 04m 32.8s) |   C |    60 | 18.9 |        
    1063 | 2026-02-23 04:28:23 |         MASTER-OAFA | (07h 22m 38.43s , -29d 04m 32.7s) |   C |    60 | 19.2 |        
    1129 | 2026-02-23 04:29:29 |         MASTER-OAFA | (07h 22m 38.49s , -29d 04m 32.7s) |   C |    60 | 19.1 |        
    1196 | 2026-02-23 04:30:35 |         MASTER-OAFA | (07h 22m 38.53s , -29d 04m 32.7s) |   C |    60 | 19.1 |        
    1261 | 2026-02-23 04:31:40 |         MASTER-OAFA | (07h 22m 38.57s , -29d 04m 32.8s) |   C |    60 | 18.9 |        
    1326 | 2026-02-23 04:32:46 |         MASTER-OAFA | (07h 22m 38.61s , -29d 04m 33.1s) |   C |    60 | 18.9 |        
    1393 | 2026-02-23 04:33:52 |         MASTER-OAFA | (07h 22m 38.66s , -29d 04m 33.1s) |   C |    60 | 19.0 |        
    1458 | 2026-02-23 04:34:58 |         MASTER-OAFA | (07h 22m 38.71s , -29d 04m 33.0s) |   C |    60 | 18.8 |        
    1524 | 2026-02-23 04:36:04 |         MASTER-OAFA | (07h 22m 38.76s , -29d 04m 33.3s) |   C |    60 | 19.2 |        
    1591 | 2026-02-23 04:37:10 |         MASTER-OAFA | (07h 22m 38.81s , -29d 04m 33.5s) |   C |    60 | 19.2 |        
    1656 | 2026-02-23 04:38:15 |         MASTER-OAFA | (07h 22m 38.85s , -29d 04m 33.5s) |   C |    60 | 19.2 |        
    1721 | 2026-02-23 04:39:21 |         MASTER-OAFA | (07h 22m 38.89s , -29d 04m 33.7s) |   C |    60 | 19.1 |

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 #43810
T. Preis (University of Innsbruck) & J. Greiner (MPE Garching) report:
The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger 793512674 at 04:11:09 on 23 Feb. 2026 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) = 109.5 deg
Decl.(2000.0) = -28.9 deg
```
The 1 sigma statistical error radius is 1.7 deg. We estimate an additional systematic error of 1 deg.
Further details are available at: https://grb.mpe.mpg.de/grb/GRB260223174/
The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB260223174/healpix
The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB260223174/json
GCN Circular #43811
Rosa L. Becerra (UNAM), Alan M. Watson (UNAM), Camila Angulo Valdez (UNAM), Nat Butler (ASU), Simone Dichiara (Penn State University), Tsvetelina Dimitrova (ASU), Alexander Kutyrev (GSFC/UMD), William H. Lee (UNAM), Océlotl López (UNAM), Margarita Pereyra (UNAM) and Eleonora Troja (U Roma) report:
We observe the field of GRB 260223A (Fermi Team, GCN Circ. 43808) with the DDOTI/OAN wide-field imager at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir (http://ddoti.astroscu.unam.mx) on the night of 2026-02-23 UTC. DDOTI observed from 04:26 UTC to 04:36 UTC (T+14.9 minutes to T+25.3 minutes after the trigger), with a total exposure time of 8 minutes.
Comparing our observations with the USNO-B1 and Pan-STARRS PS1 DR2 catalogues, we detect an uncatalogued fading source at:
```
RA = 07:24:21.20 (111.0883 deg)
DEC = -29:25:04.4 (-29.4179 deg)
```
at a preliminary AB magnitude of:
w = 18.30 +/- 0.13
at T + 14.9 minutes. From our observations, we estimate a temporal decay of approximately −0.6. We suggest that this source is the optical counterpart of GRB 260223A and encourage follow-up observations.
We thank the staff of the Observatorio Astronómico Nacional on the Sierra of San Pedro Mártir.
GCN Circular #43812
Antonio de Ugarte Postigo (LAM), Leonardo García García (UNAM), Rosa L. Becerra (UNAM), Jean-Grégoire Ducoin (CPPM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Alan M. Watson (UNAM), Edilberto Aguilar-Ruiz (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Francis Fortin (IRAP), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Asuka Kuwata (UNAM), Nikos Mandarakas (LAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), and Benjamin Schneider (LAM) report:
We imaged the field of the Fermi GRB 260223A (Fermi GBM team et al., GCN Circ. 43808) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-02-23 06:16:02 to 06:26:30 UTC (from 2.081 to 2.256 hours after the trigger) and obtained 3x60 s of simultaneous exposure in the grizy filters.
The data were reduced, coadded and analysed with the COLIBRÍ pipeline. The photometry was calibrated using nearby stars from the PanSTARRS DR2, is in the AB system, and is not corrected for Galactic extinction (A_V = 0.68, Schlafly et al. 2011).
We detected the optical counterpart reported by Becerra et al., GCN Circ. 43811, at preliminary magnitudes of:
```
g = 19.44 +/- 0.06
r = 18.92 +/- 0.04
i = 18.52 +/- 0.05 
z = 18.27 +/- 0.04
y = 18.23 +/- 0.07
```
Further observations are ongoing.
We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams.
COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico.
GCN Circular #43814
Antonio de Ugarte Postigo (LAM), Leonardo García García (UNAM), Rosa L. Becerra (UNAM), Jean-Grégoire Ducoin (CPPM), Alan M. Watson (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Jean-Luc Atteia (IRAP), Edilberto Aguilar-Ruiz (UNAM), Dalya Akl (NYUAD), Camila Angulo (UNAM), Sarah Antier (IJCLAB), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Francis Fortin (IRAP), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Asuka Kuwata (UNAM), Nikos Mandarakas (LAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), and Benjamin Schneider (LAM) report:
We continued to observe the field of the Fermi GRB 260223A (Fermi GBM team et al., GCN Circ. 43808) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-02-23 06:16 to 07:48 UTC (from 2.08 to 3.67 hours after the trigger) and obtained near-continuous, alternating 60-second exposures in the grizy filters.
The data were reduced, coadded, calibrated, and analysed with the COLIBRÍ ASU pipeline. The photometry was calibrated using nearby stars from the PanSTARRS DR2, is in the AB system, and is not corrected for Galactic extinction (A_V = 0.68, Schlafly et al. 2011).
The optical counterpart reported by Becerra et al. (GCN Circ. 43811) and confirmed by our earlier observations (de Ugarte Postiga et al. GCN Circ 43812) is observed to brighten continuously during our extended observations, rising from i = 18.55 at the start of our observations to i = 18.15 at the end. Similar behaviour is seen in the other bands.
We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams.
COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico.
GCN Circular #43815
SVOM/GRM team: Yue Wang, Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)
SVOM/ECLAIRs team: Nicolas Dagoneau (CEA)
Report on behalf of the SVOM team:
SVOM/GRM was triggered in-flight by GRB 260223A (SVOM trigger reference: sb26022301) at 2026-02-23T04:11:28.000 (T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #43808).
With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of multiple pulses with a T90 of 26 +8/-4 s in the 15-5000 keV band.
The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb260223A.png
In addition, the position of this burst, as determined by Fermi/GBM (RA = 110.5, Dec = -29.4, Error = 1.7, GCN #43808), is located at about 96 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view. ECLAIRs was not collecting data at the time of this burst.
With this localization, the time-averaged spectrum from T0-23 to T0+15 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.29 +0.10/-0.11 and the cutoff energy, parameterized as Epeak, is 194 +33/-25 keV. The event fluence (10-1000 keV) in this time interval is (2.27 +0.13/-0.13)E-05 erg/cm^2.
The 1s peak spectrum, measured from T0-0 to T0+1 s, if fitted by a power law function with an exponential high-energy cutoff, the power law index is -1.39 +0.10/-0.11 and the cutoff energy, parameterized as Epeak, is 741 +456/-228 keV. The flux (10-1000 keV) in this time interval is (3.03 +0.18/-0.18)E-06 erg/cm^2/s.
The localization of GRB 260223A in the 'Amati' relation diagram is shown at: https://www.bursthub.cn//admin/static/svgrb260223A_amati.png The localization of GRB 260223A in the 'Yonetoku' relation diagram is shown at: https://www.bursthub.cn//admin/static/svgrb260223A_yonetoku.png
The SVOM/VT ToO has been performed.
The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS.
The SVOM/GRM point of contact for this burst is: Yue Wang (IHEP) (yuewang@ihep.ac.cn)
GCN Circular #43816
H. L. Li, Y. N. Ma, L. P. Xin, Y. L. Qiu, C. Wu, Z. H. Yao, X. H. Han, Y. Xu, J. Wang, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. R. Xu, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA) report on behalf of the SVOM/VT team.
SVOM/VT performed a Target of Opportunity observation of GRB 260223A detected by Fermi (Fermi GBM team et al., GCN 43808; Preis et al., GCN 43810) and SVOM/GRM (sb26022301, Wang et al., GCN 43815). The observation started on 2026-02-23T15:26:24 UTC, i.e. about 11.26 hours after the trigger time of GBM, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously.
The optical counterpart (Becerra et al., GCN 43811; Postigo et al., GCN 43812; Postigo et al., GCN 43814) were detected in both channels. The measurements in AB magnitude are derived as follows:
```
Mid time     | Band  | Exposure Time |   Magnitude (AB)
14.893 hours   VT_R     27*70 sec      19.66 +/- 0.06 mag    
14.864 hours   VT_B     28*70 sec      20.50 +/- 0.08 mag
```
The counterpart showed a power-law decay with the index of -1.1 during our observation from 11.40 hours to 15.14 hours.
Our photometry was not corrected for Galactic extinction.
The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC), CAS.
GCN Circular #43820
Antonio de Ugarte Postigo (LAM), Fredd Sánchez Álvarez (UNAM), Alan M. Watson (UNAM), Rosa L. Becerra (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Jean-Luc Atteia (IRAP), Edilberto Aguilar-Ruiz (UNAM), Dalya Akl (NYUAD), Camila Angulo (UNAM), Sarah Antier (IJCLAB), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Asuka Kuwata (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Nikos Mandarakas (LAM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), and Benjamin Schneider (LAM) report:
We continued to observe the field of the Fermi GRB 260223A (Fermi GBM team et al., GCN Circ. 43808) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed in two epochs between 2026-02-24 02:23:16 and 07:15:39 UTC (between 22.20 and 27.07 hours after the trigger) obtaining images in the grizy filters on the first and rz on the second.
The data were reduced, coadded, calibrated, and analysed with the COLIBRÍ ASU pipeline. The photometry was calibrated using nearby stars from the PanSTARRS DR2, is in the AB system, and is not corrected for Galactic extinction.
The optical counterpart reported by Becerra et al. (GCN Circ. 43811) and confirmed by our earlier observations (de Ugarte Postigo et al. GCN Circ 43812) has decayed after the early rebrightnening (de Ugarte Postigo et al. GCN Circ 43814). On our latest stack, we detect the afterglow of GRB 260223A at r = 20.93 +/- 0.07 mag. Between our last observation obtained yesterday and today’s observations, we measure a decay slope of alpha ~ -1.1 (where F_nu ~ t ^ alpha). This is consistent with the observations obtained by SVOM/VT a few hours before (Li et al. GCN Circ. 43816) and serves to confirm that this object is indeed the afterglow of GRB 260223A.
We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams.
COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico.
GCN Circular #43824
R. Woolf, C.C. Cheung, 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 260223A, which was also detected by Fermi GBM (GCN 43808) and SVOM/GRM (GCN 43815).
Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2026-02-23 04:11:09.520 with a duration of 20.5 s and a total significance of about 48.4 sigma. Following the initial event onset, the light curve comprises two main peaks at ~T0+11s and +18s. Note that data from ~T0+15s to T0+17s 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 #43835
P. Veres (UAH) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team:
"At 04:11:09.81 UT on 23 February 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260223A (trigger 793512674/260223174), which was also detected by DDOTI (Becerra et al. 2026, GCN 43811), COLIBRI (de Ugarte Postigo et al. 2026, GCNs 43812, 43814 & 43820), SVOM/GRM (Wang et al. 2026, GCN 43815), SVOM/VT (Li et al. 2026, GCN 43816) and Glowbug (Woolf et al. 2026, GCN 43824).
The Fermi GBM on-ground location (GCN 43808) is consistent with the DDOTI position.
The angle from the Fermi LAT boresight is 33 degrees.
The GBM light curve consists of a single emission episode with a duration (T90) of about 39 s (50-300 keV). The time-averaged spectrum from T0-9.2 to T0+51.2 s is best fit by a Band function with Epeak = 70 +/- 6 keV, alpha = -0.76 +/- 0.09, and beta = -1.91 +/- 0.02.
The event fluence (10-1000 keV) in this time interval is (2.16 +/- 0.03)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+18 s in the 10-1000 keV band is 10.4 +/- 0.3 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 #43863
YoungPyo Hong (SNU ARC/SNU), Myungshin Im (SNU ARC/SNU), Donggeun Tak (SNU ARC/SNU), Hyeonho Choi (SNU ARC/SNU), Donghwan Hyun (SNU ARC/SNU), Gregory S.H. Paek (IfA, SNU ARC/SNU), Seo-Won Chang (SNU ARC/SNU), Ji Hoon Kim (SNU ARC/SNU), and Won-Hyeong Lee (SNU ARC/SNU), report on behalf of the 7 Dimensional Telescope (7DT) team:
We report optical follow-up observations of GRB26023A (GCN 43808; GCN 43809), conducted with the 7-Dimensional Telescope (7DT), located in Chile.
The 7DT follow-up began at 04:44:14 UTC on 2026-02-23, corresponding to T0 + 33 minutes, pointing to a region covering the target localization provided by Fermi (GCN 43808) at RA, DEC = 110.5 deg, -29.4 deg with an uncertainty of 1.7 degree.
Initial observations were made with 15, units in 19 medium-band filters as well as r-band filters (20 filters in total).
The following table summarizes the observations and the derived 5-sigma upper limits:

Filter       Mag          Mag_err      Exposure        Date Time                     
----------------------------------------------------------------------------------------------------
r            19.05        0.08         300.0           2026-02-23T04:49:44.000       
m400         >19.02       N/A          300.0           2026-02-23T04:44:14.000       
m425         19.28        0.16         300.0           2026-02-23T04:44:31.667       
m450         19.48        0.24         300.0           2026-02-23T04:44:16.667       
m475         18.97        0.12         300.0           2026-02-23T04:44:15.000       
m500         19.62        0.27         300.0           2026-02-23T04:44:20.667       
m525         19.48        0.24         300.0           2026-02-23T04:44:23.000       
m550         >19.29       N/A          300.0           2026-02-23T04:49:38.000       
m575         18.95        0.14         300.0           2026-02-23T04:51:58.000       
m600         18.92        0.20         300.0           2026-02-23T04:49:39.333       
m625         18.79        0.22         300.0           2026-02-23T04:49:37.000       
m650         18.66        0.22         300.0           2026-02-23T04:44:38.000       
m675         >18.95       N/A          300.0           2026-02-23T04:44:23.000       
m700         18.13        0.18         300.0           2026-02-23T04:44:18.000       
m725         >18.46       N/A          300.0           2026-02-23T04:44:23.000       
m750         18.23        0.22         300.0           2026-02-23T04:44:20.667       
m775         17.99        0.31         300.0           2026-02-23T04:44:43.333       
m800         >17.52       N/A          300.0           2026-02-23T04:44:21.667       
m825         >17.41       N/A          300.0           2026-02-23T04:44:21.333       
m850         >17.05       N/A          300.0           2026-02-23T04:44:21.000       
----------------------------------------------------------------------------------------------------

* Upper limits (marked with '>') are 5-sigma limits
The optical counterpart was detected in most filters.
Photometric flux calibration was performed using synthetic photometry based on the Gaia DR3 XP catalog (Gaia Collaboration et al. 2022) within the AB magnitude system. Note that no extinction correction has been applied.
The 7-Dimensional Telescope (7DT), located in Chile and comprising 20 wide-field telescopes equipped with 40 medium-bandwidth (~25nm) filters, aims to detect optical counterparts of GW sources and conduct the 7-Dimensional Sky Survey (7DS) of the Southern Hemisphere. Further information about the 7DT is available at https://7ds.snu.ac.kr/ and http://gwuniverse.snu.ac.kr/.

GCN Circular #43871
GRID detection of GRB 260223A
Longhao Li, Xinyu Liu, Chenyu Wang report on behalf of the GRID Collaboration:
GRID-11B reports the detection of the long-duration GRB 260223A, which was also detected by Fermi GBM (GCN Circular 43808), MASTER-OAFA (GCN Circular 43809), BALROG (GCN Circular 43810), DDOTI (GCN Circular 43811), COLIBRÍ(GCN Circular 43812), SVOM (GCN Circular 43815), Glowbug (GCN Circular 43824)
The event was triggered with GRID on 2026-02-23 at 04:11:09 UTC. The measured burst duration (T90) in the 30-2000 keV range is approximately 22.2 +/- 3.0 seconds.
The GRID light curve of this event can be found at [GRID_GRB260223A_ltcv.pdf](https://mirrors.tuna.tsinghua.edu.cn/GRID/data/GRID-GCN/GRB260223A/GRID_GRB260223A_ltcv.pdf).
GRID is a student-led project to monitor the transient gamma-ray sky with multiple detectors onboard different nanosatellites in the era of multi-messenger astronomy. For more information about GRID, please refer to the following references: https://doi.org/10.1007/s10686-019-09636-w and https://doi.org/10.1007/s10686-021-09819-4.

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Jochen Greiner, last update: 28-Feb-2026 [Disclaimer]