Gamma-ray Burst 251103B

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 03 Nov 25 16:46:49 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1409824,   Seg_Num: 0
GRB_RA:          105.864d {+07h 03m 27s} (J2000),
                 106.131d {+07h 04m 31s} (current),
                 105.347d {+07h 01m 23s} (1950)
GRB_DEC:         -24.843d {-24d 50' 35"} (J2000),
                 -24.883d {-24d 52' 58"} (current),
                 -24.768d {-24d 46' 05"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       2083 [cnts]    Image_Peak=204 [image_cnts]
TRIGGER_DUR:     0.512 [sec] 
TRIGGER_INDEX:   124     E_range: 25-100 keV
BKG_INTEN:       16404 [cnts]
BKG_TIME:        60379.37 SOD {16:46:19.37} UT
BKG_DUR:         8 [sec]
GRB_DATE:        20982 TJD;   307 DOY;   25/11/03
GRB_TIME:        60396.33 SOD {16:46:36.33} UT
GRB_PHI:         167.50 [deg]
GRB_THETA:        16.31 [deg]
SOLN_STATUS:     0x20000003
RATE_SIGNIF:     30.93 [sigma]
IMAGE_SIGNIF:    11.84 [sigma]
MERIT_PARAMS:     +1  +0  +0  -1  +2  +1  +0  +1 +23  +0 
SUN_POSTN:       219.08d {+14h 36m 20s}  -15.29d {-15d 17' 06"}
SUN_DIST:        103.32 [deg]   Sun_angle= 7.5 [hr] (West of Sun)
MOON_POSTN:       13.11d {+00h 52m 26s}   +8.30d {+08d 18' 07"}
MOON_DIST:        96.20 [deg]
MOON_ILLUM:      95 [%]
GAL_COORDS:      236.52, -8.58 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      111.38,-47.11 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Coordinates.  
COMMENTS:        This is a rate trigger.  
COMMENTS:        A point_source was found.  
COMMENTS:        This does not match any source in the on-board catalog.  
COMMENTS:        This does not match any source in the ground catalog.  
COMMENTS:        This is a GRB.  
COMMENTS:        This trigger occurred at longitude,latitude = 145.09,-6.15 [deg].  
COMMENTS:           
COMMENTS:        NOTE: This BAT event is temporally(0.0<100sec) coincident with the FERMI_GBM event (trignum=783881201).

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 03 Nov 25 16:46:56 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      48
TRIGGER_NUM:     783881201
GRB_RA:          114.850d {+07h 39m 24s} (J2000),
                 115.129d {+07h 40m 31s} (current),
                 114.310d {+07h 37m 14s} (1950)
GRB_DEC:         -21.617d {-21d 37' 00"} (J2000),
                 -21.677d {-21d 40' 38"} (current),
                 -21.501d {-21d 30' 02"} (1950)
GRB_ERROR:       13.28 [deg radius, statistical plus systematic]
GRB_INTEN:       231 [cnts/sec]
DATA_SIGNIF:     7.90 [sigma]
INTEG_TIME:      0.512 [sec]
GRB_DATE:        20982 TJD;   307 DOY;   25/11/03
GRB_TIME:        60396.44 SOD {16:46:36.44} UT
GRB_PHI:         265.98 [deg]
GRB_THETA:        65.00 [deg]
DATA_TIME_SCALE: 0.5120 [sec]
HARD_RATIO:      1.22
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      98%  GRB
2nd_MOST_LIKELY:   1%  Generic SGR
DETECTORS:       0,0,0, 0,0,0, 0,1,1, 0,0,0, 0,0,
SUN_POSTN:       219.08d {+14h 36m 20s}  -15.29d {-15d 17' 06"}
SUN_DIST:         96.82 [deg]   Sun_angle= 6.9 [hr] (West of Sun)
MOON_POSTN:       13.11d {+00h 52m 26s}   +8.30d {+08d 18' 09"}
MOON_DIST:       104.17 [deg]
MOON_ILLUM:      95 [%]
GAL_COORDS:      237.51,  0.22 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      121.91,-42.34 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251103699/quicklook/glg_lc_medres34_bn251103699.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 181.45,14.13 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(0.0<100sec) coincident with the SWIFT_BAT event (trignum=1409824).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 03 Nov 25 16:47:04 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      59
TRIGGER_NUM:     783881201
GRB_RA:          112.917d {+07h 31m 40s} (J2000),
                 113.221d {+07h 32m 53s} (current),
                 112.328d {+07h 29m 19s} (1950)
GRB_DEC:         -11.483d {-11d 28' 59"} (J2000),
                 -11.540d {-11d 32' 22"} (current),
                 -11.376d {-11d 22' 33"} (1950)
GRB_ERROR:       9.43 [deg radius, statistical plus systematic]
GRB_INTEN:       150 [cnts/sec]
DATA_SIGNIF:     12.50 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        20982 TJD;   307 DOY;   25/11/03
GRB_TIME:        60396.44 SOD {16:46:36.44} UT
GRB_PHI:         260.98 [deg]
GRB_THETA:        55.00 [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, 0,1,1, 0,0,0, 0,0,
SUN_POSTN:       219.08d {+14h 36m 20s}  -15.29d {-15d 17' 06"}
SUN_DIST:        101.87 [deg]   Sun_angle= 7.1 [hr] (West of Sun)
MOON_POSTN:       13.11d {+00h 52m 27s}   +8.30d {+08d 18' 11"}
MOON_DIST:       101.48 [deg]
MOON_ILLUM:      95 [%]
GAL_COORDS:      227.75,  3.53 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      117.00,-32.80 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251103699/quicklook/glg_lc_medres34_bn251103699.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 181.45,14.13 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(0.0<100sec) coincident with the SWIFT_BAT event (trignum=1409824).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 03 Nov 25 16:47:14 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      58
TRIGGER_NUM:     783881201
GRB_RA:          108.410d {+07h 13m 38s} (J2000),
                 108.693d {+07h 14m 46s} (current),
                 107.863d {+07h 11m 27s} (1950)
GRB_DEC:         -19.560d {-19d 33' 35"} (J2000),
                 -19.606d {-19d 36' 20"} (current),
                 -19.473d {-19d 28' 23"} (1950)
GRB_ERROR:       5.24 [deg radius, statistical only]
DATA_SIGNIF:     15.90 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        20982 TJD;   307 DOY;   25/11/03
GRB_TIME:        60396.44 SOD {16:46:36.44} UT
GRB_PHI:         259.00 [deg]
GRB_THETA:        64.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4173 (Gnd S/W Version number)
SUN_POSTN:       219.08d {+14h 36m 20s}  -15.29d {-15d 17' 06"}
SUN_DIST:        103.19 [deg]   Sun_angle= 7.4 [hr] (West of Sun)
MOON_POSTN:       13.11d {+00h 52m 27s}   +8.30d {+08d 18' 14"}
MOON_DIST:        98.00 [deg]
MOON_ILLUM:      95 [%]
GAL_COORDS:      232.83, -4.10 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      113.42,-41.51 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251103699/quicklook/glg_lc_medres34_bn251103699.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_783881201.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.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(0.0<100sec) coincident with the SWIFT_BAT event (trignum=1409824).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 03 Nov 25 16:47:50 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      0
TRIGGER_NUM:     783881201
GRB_RA:          109.290d {+07h 17m 10s} (J2000),
                 109.586d {+07h 18m 21s} (current),
                 108.717d {+07h 14m 52s} (1950)
GRB_DEC:         -14.360d {-14d 21' 35"} (J2000),
                 -14.408d {-14d 24' 27"} (current),
                 -14.269d {-14d 16' 09"} (1950)
GRB_ERROR:       3.96 [deg radius, statistical only]
DATA_SIGNIF:     16.00 [sigma]
DATA_INTERVAL:   5.120 [sec]
GRB_DATE:        20982 TJD;   307 DOY;   25/11/03
GRB_TIME:        60396.44 SOD {16:46:36.44} UT
GRB_PHI:         258.00 [deg]
GRB_THETA:        59.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       219.08d {+14h 36m 20s}  -15.29d {-15d 17' 07"}
SUN_DIST:        104.26 [deg]   Sun_angle= 7.3 [hr] (West of Sun)
MOON_POSTN:       13.12d {+00h 52m 28s}   +8.31d {+08d 18' 24"}
MOON_DIST:        98.27 [deg]
MOON_ILLUM:      95 [%]
GAL_COORDS:      228.61, -0.95 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      113.38,-36.25 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251103699/quicklook/glg_lc_medres34_bn251103699.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_783881201.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.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(0.0<100sec) coincident with the SWIFT_BAT event (trignum=1409824).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 03 Nov 25 16:48:25 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      1
TRIGGER_NUM:     783881201
GRB_RA:          107.480d {+07h 09m 55s} (J2000),
                 107.777d {+07h 11m 06s} (current),
                 106.906d {+07h 07m 38s} (1950)
GRB_DEC:         -14.140d {-14d 08' 23"} (J2000),
                 -14.184d {-14d 11' 00"} (current),
                 -14.058d {-14d 03' 27"} (1950)
GRB_ERROR:       3.10 [deg radius, statistical only]
DATA_SIGNIF:     17.00 [sigma]
DATA_INTERVAL:   9.216 [sec]
GRB_DATE:        20982 TJD;   307 DOY;   25/11/03
GRB_TIME:        60396.44 SOD {16:46:36.44} UT
GRB_PHI:         256.00 [deg]
GRB_THETA:        59.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       219.09d {+14h 36m 20s}  -15.29d {-15d 17' 07"}
SUN_DIST:        105.98 [deg]   Sun_angle= 7.4 [hr] (West of Sun)
MOON_POSTN:       13.12d {+00h 52m 30s}   +8.31d {+08d 18' 34"}
MOON_DIST:        96.50 [deg]
MOON_ILLUM:      95 [%]
GAL_COORDS:      227.60, -2.40 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      111.19,-36.30 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251103699/quicklook/glg_lc_medres34_bn251103699.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_783881201.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.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(0.0<100sec) coincident with the SWIFT_BAT event (trignum=1409824).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 03 Nov 25 16:55:55 UT
NOTICE_TYPE:     Fermi-GBM Final Position
RECORD_NUM:      0
TRIGGER_NUM:     783881201
GRB_RA:          107.530d {+07h 10m 07s} (J2000),
                 107.806d {+07h 11m 13s} (current),
                 106.997d {+07h 07m 59s} (1950)
GRB_DEC:         -22.040d {-22d 02' 23"} (J2000),
                 -22.084d {-22d 05' 00"} (current),
                 -21.957d {-21d 57' 26"} (1950)
GRB_ERROR:       4.26 [deg radius, statistical only]
GRB_DATE:        20982 TJD;   307 DOY;   25/11/03
GRB_TIME:        60396.44 SOD {16:46:36.44} UT
GRB_PHI:         259.00 [deg]
GRB_THETA:        67.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       219.09d {+14h 36m 22s}  -15.29d {-15d 17' 13"}
SUN_DIST:        103.02 [deg]   Sun_angle= 7.4 [hr] (West of Sun)
MOON_POSTN:       13.19d {+00h 52m 46s}   +8.34d {+08d 20' 40"}
MOON_DIST:        97.37 [deg]
MOON_ILLUM:      95 [%]
GAL_COORDS:      234.67, -5.97 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      112.88,-44.10 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251103699/quicklook/glg_lc_medres34_bn251103699.gif
LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251103699/quicklook/glg_locplot_all_bn251103699.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.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(0.0<100sec) coincident with the SWIFT_BAT event (trignum=1409824).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 03 Nov 25 16:48:23 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     1409824,   Seg_Num: 0
GRB_RA:          105.8735d {+07h 03m 29.6s} (J2000),
                 106.1404d {+07h 04m 33.7s} (current),
                 105.3571d {+07h 01m 25.6s} (1950)
GRB_DEC:         -24.8709d {-24d 52' 15.2"} (J2000),
                 -24.9106d {-24d 54' 38.0"} (current),
                 -24.7960d {-24d 47' 45.4"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       92 [cnts]
IMG_START_DATE:  20982 TJD;   307 DOY;   25/11/03
IMG_START_TIME:  60469.26 SOD {16:47:49.26} UT,   72.9 [sec] since BAT Trigger Time
CENTROID_X:      296.43,  raw= 296  [pixels]
CENTROID_Y:      264.80,  raw= 265  [pixels]
ROLL:            114.23 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -79.91
GRB_POS_XRT_Z:   -35.74
IMAGE_URL:       sw01409824000msxps_rw.img
SUN_POSTN:       219.09d {+14h 36m 20s}  -15.29d {-15d 17' 07"}
SUN_DIST:        103.30 [deg]   Sun_angle= 7.5 [hr] (West of Sun)
MOON_POSTN:       13.12d {+00h 52m 30s}   +8.31d {+08d 18' 33"}
MOON_DIST:        96.21 [deg]
MOON_ILLUM:      95 [%]
GAL_COORDS:      236.54, -8.59 [deg] galactic lon,lat of the burst
ECL_COORDS:      111.40,-47.14 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 03 Nov 25 16:48:13 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     1409824,   Seg_Num: 0
GRB_RA:          105.8735d {+07h 03m 29.64s} (J2000),
                 106.1404d {+07h 04m 33.70s} (current),
                 105.3571d {+07h 01m 25.69s} (1950)
GRB_DEC:         -24.8709d {-24d 52' 15.2"} (J2000),
                 -24.9106d {-24d 54' 38.0"} (current),
                 -24.7960d {-24d 47' 45.4"} (1950)
GRB_ERROR:       5.0 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       2.78e-09 [erg/cm2/sec]
GRB_SIGNIF:      9.59 [sigma]
IMG_START_DATE:  20982 TJD;   307 DOY;   25/11/03
IMG_START_TIME:  60469.26 SOD {16:47:49.26} UT,   72.9 [sec] since BAT Trigger Time
TAM[0-3]:        327.63 237.14 261.46 243.91
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       219.09d {+14h 36m 20s}  -15.29d {-15d 17' 07"}
SUN_DIST:        103.30 [deg]   Sun_angle= 7.5 [hr] (West of Sun)
MOON_POSTN:       13.12d {+00h 52m 29s}   +8.31d {+08d 18' 30"}
MOON_DIST:        96.21 [deg]
MOON_ILLUM:      95 [%]
GAL_COORDS:      236.54, -8.59 [deg] galactic lon,lat of the burst
ECL_COORDS:      111.40,-47.14 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 1.74 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 03 Nov 25 16:50:18 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1409824,   Seg_Num: 0
GRB_RA:          105.864d {+07h 03m 27s} (J2000),
                 106.131d {+07h 04m 31s} (current),
                 105.347d {+07h 01m 23s} (1950)
GRB_DEC:         -24.843d {-24d 50' 35"} (J2000),
                 -24.883d {-24d 52' 58"} (current),
                 -24.768d {-24d 46' 05"} (1950)
GRB_DATE:        20982 TJD;   307 DOY;   25/11/03
GRB_TIME:        60396.33 SOD {16:46:36.33} UT
TRIGGER_INDEX:   124
GRB_PHI:         167.50 [deg]
GRB_THETA:        16.31 [deg]
DELTA_TIME:      64.00 [sec]
TRIGGER_DUR:     0.512 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     30.93 [sigma]
IMAGE_SIGNIF:    11.84 [sigma]
LC_URL:          sw01409824000msb.lc
SUN_POSTN:       219.09d {+14h 36m 21s}  -15.29d {-15d 17' 09"}
SUN_DIST:        103.32 [deg]   Sun_angle= 7.5 [hr] (West of Sun)
MOON_POSTN:       13.14d {+00h 52m 34s}   +8.32d {+08d 19' 05"}
MOON_DIST:        96.18 [deg]
MOON_ILLUM:      95 [%]
GAL_COORDS:      236.52, -8.58 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      111.38,-47.11 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Lightcurve.  
COMMENTS:           
COMMENTS:        The next comments were copied from the BAT_POS Notice:  
COMMENTS:        This is a rate trigger.  
COMMENTS:        A point_source was found.  
COMMENTS:        This does not match any source in the on-board catalog.  
COMMENTS:        This does not match any source in the ground catalog.  
COMMENTS:        This is a GRB.  
COMMENTS:        This trigger occurred at longitude,latitude = 145.09,-6.15 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 03 Nov 25 16:48:25 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     1409824,   Seg_Num: 0
GRB_RA:          105.8735d {+07h 03m 29.6s} (J2000),
                 106.1404d {+07h 04m 33.7s} (current),
                 105.3571d {+07h 01m 25.6s} (1950)
GRB_DEC:         -24.8709d {-24d 52' 15.2"} (J2000),
                 -24.9106d {-24d 54' 38.0"} (current),
                 -24.7960d {-24d 47' 45.4"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       92 [cnts]
IMG_START_DATE:  20982 TJD;   307 DOY;   25/11/03
IMG_START_TIME:  60469.26 SOD {16:47:49.26} UT,   72.9 [sec] since BAT Trigger Time
CENTROID_X:      296.43,  raw= 296  [pixels]
CENTROID_Y:      264.80,  raw= 265  [pixels]
ROLL:            114.23 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -79.91
GRB_POS_XRT_Z:   -35.74
IMAGE_URL:       sw01409824000msxps_rw.img
SUN_POSTN:       219.09d {+14h 36m 20s}  -15.29d {-15d 17' 07"}
SUN_DIST:        103.30 [deg]   Sun_angle= 7.5 [hr] (West of Sun)
MOON_POSTN:       13.12d {+00h 52m 30s}   +8.31d {+08d 18' 34"}
MOON_DIST:        96.21 [deg]
MOON_ILLUM:      95 [%]
GAL_COORDS:      236.54, -8.59 [deg] galactic lon,lat of the burst
ECL_COORDS:      111.40,-47.14 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 03 Nov 25 16:53:36 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1409824,   Seg_Num: 0
POINT_RA:        105.873d {+07h 03m 30s} (J2000)
POINT_DEC:       -24.848d {-24d 50' 51"} (J2000)
POINT_ROLL:      114.234d
IMG_START_DATE:  20982 TJD;   307 DOY;   25/11/03
IMG_START_TIME:  60536.07 SOD {16:48:56.07} UT,   139.7 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.356
N_STARS:         190
X_OFFSET:        0 [pixels]
Y_OFFSET:        0 [pixels]
X_MAX:           2047 [pixels]
Y_MAX:           2047 [pixels]
DET_THRESH:      6
PHOTO_THRESH:    2
SL_URL:          sw01409824000msufc0139.fits
SUN_POSTN:       219.09d {+14h 36m 21s}  -15.29d {-15d 17' 11"}
SUN_DIST:        103.31 [deg]   Sun_angle= 7.5 [hr] (West of Sun)
MOON_POSTN:       13.17d {+00h 52m 41s}   +8.33d {+08d 20' 01"}
MOON_DIST:        96.17 [deg]
MOON_ILLUM:      95 [%]
GAL_COORDS:      236.52, -8.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      111.39,-47.12 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN Circular #42555
The Fermi GBM team reports the detection of a likely LONG GRB
At 16:46:36 UT on 3 Nov 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251103B (trigger 783881201.440798 / 251103699).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 107.5, Dec = -22.0 (J2000 degrees, equivalent to J2000 07h 10m, -22d 00'), with a statistical uncertainty of 4.3 degrees.
The angle from the Fermi LAT boresight is 67.0 degrees.
The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251103699/quicklook/glg_skymap_all_bn251103699.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/bn251103699/quicklook/glg_healpix_all_bn251103699.fit
The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251103699/quicklook/glg_lc_medres34_bn251103699.gif

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 03 Nov 25 17:04:00 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1409824,   Seg_Num: 0
POINT_RA:        105.873d {+07h 03m 30s} (J2000)
POINT_DEC:       -24.848d {-24d 50' 52"} (J2000)
POINT_ROLL:      114.234d
IMG_START_DATE:  20982 TJD;   307 DOY;   25/11/03
IMG_START_TIME:  61262.57 SOD {17:01:02.57} UT,   866.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.025
N_STARS:         190
X_OFFSET:        370 [pixels]
Y_OFFSET:        414 [pixels]
X_MAX:           1809 [pixels]
Y_MAX:           1853 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    8
SL_URL:          sw01409824000msufc0866.fits
SUN_POSTN:       219.10d {+14h 36m 23s}  -15.29d {-15d 17' 19"}
SUN_DIST:        103.32 [deg]   Sun_angle= 7.5 [hr] (West of Sun)
MOON_POSTN:       13.27d {+00h 53m 04s}   +8.38d {+08d 22' 57"}
MOON_DIST:        96.10 [deg]
MOON_ILLUM:      95 [%]
GAL_COORDS:      236.52, -8.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      111.39,-47.12 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 03 Nov 25 17:04:16 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1409824,   Seg_Num: 0
POINT_RA:        105.873d {+07h 03m 30s} (J2000)
POINT_DEC:       -24.848d {-24d 50' 52"} (J2000)
POINT_ROLL:      114.234d
IMG_START_DATE:  20982 TJD;   307 DOY;   25/11/03
IMG_START_TIME:  61262.57 SOD {17:01:02.57} UT,   866.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.025
N_STARS:         190
X_OFFSET:        370 [pixels]
Y_OFFSET:        414 [pixels]
X_MAX:           1809 [pixels]
Y_MAX:           1853 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    8
SL_URL:          sw01409824000msufc0866.fits
SUN_POSTN:       219.10d {+14h 36m 23s}  -15.29d {-15d 17' 20"}
SUN_DIST:        103.32 [deg]   Sun_angle= 7.5 [hr] (West of Sun)
MOON_POSTN:       13.27d {+00h 53m 05s}   +8.38d {+08d 23' 01"}
MOON_DIST:        96.10 [deg]
MOON_ILLUM:      95 [%]
GAL_COORDS:      236.52, -8.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      111.39,-47.12 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 03 Nov 25 17:04:26 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     1409824,   Seg_Num: 0
GRB_RA:          105.8735d {+07h 03m 29.64s} (J2000),
                 106.1404d {+07h 04m 33.70s} (current),
                 105.3571d {+07h 01m 25.69s} (1950)
GRB_DEC:         -24.8717d {-24d 52' 18.1"} (J2000),
                 -24.9114d {-24d 54' 40.9"} (current),
                 -24.7968d {-24d 47' 48.3"} (1950)
GRB_ERROR:       2.1 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  20982 TJD;   307 DOY;   25/11/03
IMG_START_TIME:  60621.00 SOD {16:50:21.00} UT,   224.7 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       219.10d {+14h 36m 23s}  -15.29d {-15d 17' 20"}
SUN_DIST:        103.31 [deg]   Sun_angle= 7.5 [hr] (West of Sun)
MOON_POSTN:       13.27d {+00h 53m 05s}   +8.38d {+08d 23' 04"}
MOON_DIST:        96.10 [deg]
MOON_ILLUM:      95 [%]
GAL_COORDS:      236.55, -8.59 [deg] galactic lon,lat of the burst
ECL_COORDS:      111.40,-47.14 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        This is an Update Notice -- the RA,Dec values herein supersede the previous XRT_POS Notice.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See https://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        This position was enhanced using UVOT field astrometry.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.58% < P(seren) < 1.1%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 03 Nov 25 17:05:43 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1409824,   Seg_Num: 0
POINT_RA:        105.873d {+07h 03m 30s} (J2000)
POINT_DEC:       -24.848d {-24d 50' 52"} (J2000)
ROLL:            114.234d
IMG_START_DATE:  20982 TJD;   307 DOY;   25/11/03
IMG_START_TIME:  61262.57 SOD {17:01:02.57} UT,   866.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     783882099
X_OFFSET:        929 [pixels]
Y_OFFSET:        973 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1089
Y_GRB_POS:       1133
BINNING_INDEX:   1
IM_URL:          sw01409824000msuni0903.fits
SUN_POSTN:       219.10d {+14h 36m 23s}  -15.29d {-15d 17' 21"}
SUN_DIST:        103.32 [deg]   Sun_angle= 7.5 [hr] (West of Sun)
MOON_POSTN:       13.28d {+00h 53m 08s}   +8.39d {+08d 23' 26"}
MOON_DIST:        96.09 [deg]
MOON_ILLUM:      95 [%]
GAL_COORDS:      236.52, -8.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      111.39,-47.12 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 03 Nov 25 17:05:55 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1409824,   Seg_Num: 0
POINT_RA:        105.873d {+07h 03m 30s} (J2000)
POINT_DEC:       -24.848d {-24d 50' 52"} (J2000)
ROLL:            114.234d
IMG_START_DATE:  20982 TJD;   307 DOY;   25/11/03
IMG_START_TIME:  61262.57 SOD {17:01:02.57} UT,   866.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     783882099
X_OFFSET:        929 [pixels]
Y_OFFSET:        973 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1089
Y_GRB_POS:       1133
BINNING_INDEX:   1
IM_URL:          sw01409824000msuni0903.fits
SUN_POSTN:       219.10d {+14h 36m 23s}  -15.29d {-15d 17' 21"}
SUN_DIST:        103.32 [deg]   Sun_angle= 7.5 [hr] (West of Sun)
MOON_POSTN:       13.29d {+00h 53m 09s}   +8.39d {+08d 23' 29"}
MOON_DIST:        96.09 [deg]
MOON_ILLUM:      95 [%]
GAL_COORDS:      236.52, -8.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      111.39,-47.12 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN Circular #42556
S. Lanava (PSU), S. Dichiara (PSU), R. Gupta (NASA GSFC), M. J. Moss (GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL) and B. Sbarufatti (INAF-OAB) report on behalf of the Neil Gehrels Swift Observatory Team:
At 16:46:36 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 251103B (trigger=1409824). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 105.864, -24.843 which is
```
   RA(J2000) = 07h 03m 27s
   Dec(J2000) = -24d 50' 35"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 200 sec. The peak count rate was ~4000 counts/sec (15-350 keV), at ~2 sec after the trigger.
The XRT began observing the field at 16:47:49.2 UT, 72.9 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 105.87352, -24.87083 which is equivalent to:
```
   RA(J2000)  = 07h 03m 29.64s
   Dec(J2000) = -24d 52' 15.0"
```
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This location is 104 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at https://www.swift.ac.uk/sper.
A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (3.33 x 10^21 cm^-2, Willingale et al. 2013), with an excess column of 3.5 (+2.76/-2.40) x 10^21 cm^-2 (90% confidence).
The initial flux in the 2.5 s image was 2.78e-09 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 250 seconds with the U filter starting 139 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.2 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18.0 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.255.
Burst Advocate for this burst is S. Lanava (sml7284 AT psu.edu). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/)
GCN Circular #42557
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Using 1.3 ks of promptly downlinked XRT event data for GRB 251103B, we find an enhanced XRT position of the afterglow: RA, Dec: 105.87365, -24.87162 which is equivalent to:
```
   RA (J2000)  = 07 03 29.68
   Dec (J2000) = -24 52 17.8
```
with an uncertainty of 2.0 arcseconds (radius, 90% confidence). Analysis of the promptly available data is online at http://www.swift.ac.uk/sper/1409824.
Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177).
This circular is an official product of the Swift-XRT team.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 03 Nov 25 16:54:46 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1409824,   Seg_Num: 0
POINT_RA:        105.873d {+07h 03m 30s} (J2000)
POINT_DEC:       -24.848d {-24d 50' 51"} (J2000)
ROLL:            114.234d
IMG_START_DATE:  20982 TJD;   307 DOY;   25/11/03
IMG_START_TIME:  60536.07 SOD {16:48:56.07} UT,   139.7 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     783881372
X_OFFSET:        930 [pixels]
Y_OFFSET:        974 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1090
Y_GRB_POS:       1134
BINNING_INDEX:   1
IM_URL:          sw01409824000msuni0176.fits
SUN_POSTN:       219.09d {+14h 36m 21s}  -15.29d {-15d 17' 12"}
SUN_DIST:        103.31 [deg]   Sun_angle= 7.5 [hr] (West of Sun)
MOON_POSTN:       13.18d {+00h 52m 44s}   +8.34d {+08d 20' 21"}
MOON_DIST:        96.16 [deg]
MOON_ILLUM:      95 [%]
GAL_COORDS:      236.52, -8.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      111.39,-47.12 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 03 Nov 25 16:53:55 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1409824,   Seg_Num: 0
POINT_RA:        105.873d {+07h 03m 30s} (J2000)
POINT_DEC:       -24.848d {-24d 50' 51"} (J2000)
POINT_ROLL:      114.234d
IMG_START_DATE:  20982 TJD;   307 DOY;   25/11/03
IMG_START_TIME:  60536.07 SOD {16:48:56.07} UT,   139.7 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.356
N_STARS:         190
X_OFFSET:        0 [pixels]
Y_OFFSET:        0 [pixels]
X_MAX:           2047 [pixels]
Y_MAX:           2047 [pixels]
DET_THRESH:      6
PHOTO_THRESH:    2
SL_URL:          sw01409824000msufc0139.fits
SUN_POSTN:       219.09d {+14h 36m 21s}  -15.29d {-15d 17' 12"}
SUN_DIST:        103.31 [deg]   Sun_angle= 7.5 [hr] (West of Sun)
MOON_POSTN:       13.17d {+00h 52m 42s}   +8.34d {+08d 20' 06"}
MOON_DIST:        96.17 [deg]
MOON_ILLUM:      95 [%]
GAL_COORDS:      236.52, -8.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      111.39,-47.12 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 03 Nov 25 16:55:01 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1409824,   Seg_Num: 0
POINT_RA:        105.873d {+07h 03m 30s} (J2000)
POINT_DEC:       -24.848d {-24d 50' 51"} (J2000)
ROLL:            114.234d
IMG_START_DATE:  20982 TJD;   307 DOY;   25/11/03
IMG_START_TIME:  60536.07 SOD {16:48:56.07} UT,   139.7 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     783881372
X_OFFSET:        930 [pixels]
Y_OFFSET:        974 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1090
Y_GRB_POS:       1134
BINNING_INDEX:   1
IM_URL:          sw01409824000msuni0176.fits
SUN_POSTN:       219.09d {+14h 36m 22s}  -15.29d {-15d 17' 12"}
SUN_DIST:        103.31 [deg]   Sun_angle= 7.5 [hr] (West of Sun)
MOON_POSTN:       13.18d {+00h 52m 44s}   +8.34d {+08d 20' 25"}
MOON_DIST:        96.16 [deg]
MOON_ILLUM:      95 [%]
GAL_COORDS:      236.52, -8.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      111.39,-47.12 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN Circular #42558
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team.
Using 1251 s of XRT Photon Counting mode data and 1 UVOT images for GRB 251103B, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 105.87339, -24.87217 which is equivalent to:
```
RA (J2000): 07h 03m 29.61s
Dec (J2000): -24d 52' 19.8"
```
with an uncertainty of 2.3 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest position can be viewed at https://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177).
This circular was automatically generated, and is an official product of the Swift-XRT team.
GCN Circular #42560
T. Mohan, V. Vijaykumar, V. Swain, S. Patil, A.P. Saikia, V. Bhalerao (IITB), G.C. Anupama, S. Barway (IIA) and K. Angail (IAO) report on behalf of the GIT team:
We observed the field of GRB 251103B, detected by Fermi (Fermi GBM team, GCN 42555) and Swift (Lanava et al., GCN 42556), using the 0.7m GROWTH-India Telescope (GIT). We started the observation at 2025-11-03 20:09:26 UT, i.e., 3.38 hours after the GRB trigger and obtained multiple exposures in the r' and g' filters. No optical counterpart was detected within the Swift-XRT localization region (Evans et al., GCN 42558). The photometric upper limits are as follows:
```
| MJD (mid)    | Filter | tmid-t0 (hours) | Exposure Time (sec) | Upper limit (AB) |
| ------------ | ------ | ------------ | ---------------------- | ---------------- |
| 60982.84498  |   g'   |     3.5      |         360            |      19.4        |
| 60982.85227  |   r'   |     3.68     |        4x360           |      20.5        |
```
The measurement is calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction.
The GROWTH India Telescope (GIT; Kumar et al. 2022) is a 70-cm telescope with a 0.7-degree field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports the operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/.
GCN Circular #42561
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-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB 251103B ( S. Lanava et al., GCN 42556) errorbox 16520 sec after notice time and 16537 sec after trigger time at 2025-11-03 21:22:14 UT, with upper limit up to 18.3 mag. The observations began at zenith distance = 70 deg. The sun altitude is -40.6 deg.
The galactic latitude b = -8 deg., longitude l = 237 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3031294
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

   16628 |         MASTER-SAAO |   C |   180 | 18.3 |        
   16628 |         MASTER-SAAO |   C |   180 | 17.4 |        
   16840 |         MASTER-SAAO |   C |   180 | 17.4 |        
   16840 |         MASTER-SAAO |   C |   180 | 18.3 |        
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
GCN Circular #42566
R. Brivio (INAF-OAB), A. D'Ai (INAF-IASFPA), S. Campana (INAF-OAB), S. Dichiara (PSU), J.A. Kennea (PSU), D.N. Burrows (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester) and P.A. Evans report on behalf of the Swift-XRT team:
We have analysed 6.8 ks of XRT data for GRB 251103B, from 62 s to 23.6 ks after the trigger. The data comprise 143 s in Windowed Timing (WT) mode (the first 9 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode.
The late-time light curve (from T0+10.3 ks) can be modelled with a power-law decay with a decay index of alpha=1.0 (+/-0.4).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.21 (+/-0.08). The best-fitting absorption column is 9.0 (+/-0.7) x 10^21 cm^-2, in excess of the Galactic value of 3.3 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 2.09 (+0.22, -0.21) and a best-fitting absorption column of 4.9 (+1.2, -1.1) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.0 x 10^-11 (6.8 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     4.9 (+1.2, -1.1) x 10^21 cm^-2
Galactic foreground: 3.3 x 10^21 cm^-2
Excess significance: 2.5 sigma
Photon index:	     2.09 (+0.22, -0.21)
```
If the light curve continues to decay with a power-law decay index of 1.0, the count rate at T+24 hours will be 0.014 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.4 x 10^-13 (9.2 x 10^-13) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at https://www.swift.ac.uk/xrt_products/01409824.
This circular is an official product of the Swift-XRT team.
GCN Circular #42567
I. Takahashi, H. Hagio, A. Ochi, Y. Kubo, M. Sasada, R. Kato, H. Seki, S. Joshima, Y. Yatsu and N. Kawai (Science Tokyo) report on behalf of the MITSuME collaboration:
We observed the field of GRB 251103B detected by Fermi (Fermi GBM team, GCN 42555) and Swift (Lanava et al., GCN 42556) with the optical three-color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50-cm telescope Akeno.
The observation started at 2025-11-03 16:47:11 UT (35 seconds after the trigger). We stacked the images taken under good conditions. We did not detect any obvious point sources within the enhanced Swift/XRT error region (Evans et al., GCN 42558). We obtained the 5-sigma limits of the stacked images as follows:
```
T0+[sec] | MID-UT | T-EXP[sec] | 5-sigma limits
------------------------------------------------------------------------------------------------
124 | 2025-11-03 16:48:40 | 80 | Rc>16.6, Ic>16.3
821 | 2025-11-03 17:00:17 | 1020 | g'>17.8, Rc>18.4, Ic>18.1
7041 | 2025-11-03 18:43:57 | 9180 | g'>19.4, Rc>19.5, Ic>19.1
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the trigger
T-EXP: Total exposure time
```
We used the PS1 catalog for flux calibration. The catalog magnitudes in PS1 g, r and i bands were converted to our g', Rc and Ic band magnitudes following Tonry et al. (2012), Table 6. The magnitudes are expressed in the AB system. The images were processed in real-time through the MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ; https://github.com/MNiwano/Eclaire).
GCN Circular #42570
S.Q. Jiang (NAOC), S.Y. Fu (HUST), J. An, X. Liu, L.B. He, Z.P. Zhu, D. Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:
We observed the field of GRB 251103B detected by Swift/BAT (Lanava et al., GCN 42556) and Fermi/GBM (Fermi GBM team, GCN 42555) using the HMT-0.5m telescope located at Nanshan, Xinjiang, China. Observations started at 22:31:33 UT on 2025-11-03, i.e., 5.749 hrs after the Swift/BAT trigger, we obtained 25x120 s unfiltered frames. No new optical source is detected in our stacked image within the enhanced XRT error circle (Evans et al., GCN 42558), down to the following 3-sigma limiting magnitude R>20.4 at 6.276 hrs post-burst, calibrated with the nearby PanSTARRS field and the magnitude is not corrected for Galactic extinction.
GCN Circular #42582
A. C. Trigg (NPP, NASA MSFC) report on behalf of the Fermi GBM Team:
"At 16:46:36.44 UT on 03 November 2025, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 251103B (trigger 783881201/251103699), which was also detected by the Swift/XRT (Evans et al. 2025, GCN 42557) The Fermi GBM Final Real-time Localization (GCN 42555) is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 70 degrees.
The GBM light curve shows/consists of rapid multi-peaked emission with a duration (T90) of about 15 s (50-300 keV). The time-averaged spectrum from T0-0.00 s to T0+10.0 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.07 +/- 0.02 and the cutoff energy, parameterized as Epeak, is 149 +/- 3 keV.
The event fluence (10-1000 keV) in this time interval is (2.28 +/- 0.08)E-6 erg/cm^2. The 256-msec peak photon flux measured starting from T0+2.24 s in the 10-1000 keV band is 5.6 +/- 0.5 ph/s/cm^2.
A Band function fits the spectrum equally well with Epeak= 146 +/- 3 keV, alpha = -1.07 +/- 0.01, and beta = -3.3 +/- 0.06.
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 #42588
A.A. Breeveld (UCL-MSSL) and S. Lanava (PSU) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 251103B 140 s after the BAT trigger (Lanava et al., GCN Circ. 42556). No optical afterglow consistent with the enhanced XRT position (Evans et al., GCN Circ. 42558)is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

u_FC               140          390          246         >20.2
white              420         1363          245         >21.1
v                  470         1413          117         >19.0
b                  395         1339           97         >19.8
w1                 519         1462           97         >18.8
m2                 494         1437          117         >18.8
w2                 445         1389          117         >19.1
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.256 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #42604
A. Goyal (IITB), A. Arya (IITB), S. Salunke (IUCAA), M. Tembhurnikar (IUCAA), Harsha K. H. (IUCAA), G. Waratkar (Caltech/IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:
Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long GRB 251103B which was also detected by Fermi GBM (Fermi GBM Team, GCN Circ. 42555), and Swift BAT (Lanava et. al., GCN Circ. 42556).
The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2025-11-03 16:46:36.50 UTC. The measured peak count rate associated with the burst is 87 (+31, -16) counts/s above the background in the combined data of three quadrants (out of four), with a total of 307 (+118, -98) counts. We caution that there is a 0.3 s readout dead time in CZT data during the burst which affects the calculated total counts. The local mean background count rate was 215 (+2, -4) counts/s. Using cumulative rates, we measure a T90 of 5.86 (+0.85, -2.24) s.
The source was also faintly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2025-11-03 16:46:41.66 UTC. The measured peak count rate associated with the burst is 148 (+74, -23) counts/s above the background in the combined data of all quadrants, with a total of 677 (+244, -247) counts. The local mean background count rate was 1281 (+6, -7) counts/s. Due to poor statistics, we cannot reliably estimate the T90 from it.
CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.
CZTI GRB detections are reported regularly on the payload site at: http://astrosat.iucaa.in/czti/?q=grb
GCN Circular #42636
R. Gupta (GSFC), S. D. Barthelmy (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), S. Lanava (PSU), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), M. J. Moss (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+1282 sec from the recent telemetry downlink, we report further analysis of BAT GRB 251103B (trigger #1409824) (Lanava, et al., GCN Circ. 42556). The BAT ground-calculated position is RA, Dec = 105.870, -24.871 deg which is
```
   RA(J2000)  =  07h 03m 28.7s 
   Dec(J2000) = -24d 52' 14.9" 
```
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 99%.
The mask-weighted light curve displays a complicated structure with tens of pulses. Significant emission begins at ~T0-110 seconds and ends ~T0+95 seconds. T90 (15-350 keV) is 127.86 +- 22.41 sec (estimated error including systematics).
The time-averaged spectrum from T-52.07 to T+92.74 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.79 +- 0.08. The fluence in the 15-150 keV band is 3.5 +- 0.1 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+2.00 sec in the 15-150 keV band is 2.9 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
The results of the batgrbproduct analysis are available at https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1409824

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Jochen Greiner, last update: 11-Nov-2025 [Disclaimer]