Gamma-ray Burst 241228A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 28 Dec 24 03:57:37 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1277277,   Seg_Num: 0
GRB_RA:          344.824d {+22h 59m 18s} (J2000),
                 345.132d {+23h 00m 32s} (current),
                 344.208d {+22h 56m 50s} (1950)
GRB_DEC:         +18.604d {+18d 36' 14"} (J2000),
                 +18.738d {+18d 44' 18"} (current),
                 +18.336d {+18d 20' 09"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       3751 [cnts]    Image_Peak=560 [image_cnts]
TRIGGER_DUR:     0.512 [sec] 
TRIGGER_INDEX:   41     E_range: 25-100 keV
BKG_INTEN:       15856 [cnts]
BKG_TIME:        14221.20 SOD {03:57:01.20} UT
BKG_DUR:         8 [sec]
GRB_DATE:        20672 TJD;   363 DOY;   24/12/28
GRB_TIME:        14235.16 SOD {03:57:15.16} UT
GRB_PHI:         -114.48 [deg]
GRB_THETA:        32.40 [deg]
SOLN_STATUS:     0x20000003
RATE_SIGNIF:     97.16 [sigma]
IMAGE_SIGNIF:    20.90 [sigma]
MERIT_PARAMS:     +1  +0  +0  -1  +2  +7  +0  +0 -21  +0 
SUN_POSTN:       277.52d {+18h 30m 05s}  -23.26d {-23d 15' 18"}
SUN_DIST:         78.20 [deg]   Sun_angle= -4.5 [hr] (East of Sun)
MOON_POSTN:      241.32d {+16h 05m 17s}  -25.30d {-25d 18' 08"}
MOON_DIST:       109.98 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:       89.13,-36.80 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      353.72, 23.04 [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 = 170.95,19.83 [deg].  
COMMENTS:           
COMMENTS:        NOTE: This BAT event is temporally(5.0<100sec) coincident with the FERMI_GBM event (trignum=757051035).

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 28 Dec 24 03:57:49 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      58
TRIGGER_NUM:     757051035
GRB_RA:          351.633d {+23h 26m 32s} (J2000),
                 351.940d {+23h 27m 46s} (current),
                 351.020d {+23h 24m 05s} (1950)
GRB_DEC:         +33.483d {+33d 28' 60"} (J2000),
                 +33.621d {+33d 37' 16"} (current),
                 +33.208d {+33d 12' 29"} (1950)
GRB_ERROR:       5.55 [deg radius, statistical plus systematic]
GRB_INTEN:       1003 [cnts/sec]
DATA_SIGNIF:     35.70 [sigma]
INTEG_TIME:      0.512 [sec]
GRB_DATE:        20672 TJD;   363 DOY;   24/12/28
GRB_TIME:        14230.17 SOD {03:57:10.17} UT
GRB_PHI:          63.00 [deg]
GRB_THETA:        40.00 [deg]
DATA_TIME_SCALE: 0.5120 [sec]
HARD_RATIO:      1.12
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      98%  GRB
2nd_MOST_LIKELY:   1%  Generic SGR
DETECTORS:       1,1,0, 0,0,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       277.52d {+18h 30m 05s}  -23.26d {-23d 15' 18"}
SUN_DIST:         90.75 [deg]   Sun_angle= -5.0 [hr] (East of Sun)
MOON_POSTN:      241.32d {+16h 05m 18s}  -25.30d {-25d 18' 09"}
MOON_DIST:       120.12 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      103.28,-26.13 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:        7.46, 33.67 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn241228165/quicklook/glg_lc_medres34_bn241228165.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 228.57,24.17 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(5.0<100sec) coincident with the SWIFT_BAT event (trignum=1277277).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 28 Dec 24 03:57:40 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      45
TRIGGER_NUM:     757051035
GRB_RA:          343.983d {+22h 55m 56s} (J2000),
                 344.266d {+22h 57m 04s} (current),
                 343.419d {+22h 53m 41s} (1950)
GRB_DEC:         +44.333d {+44d 19' 60"} (J2000),
                 +44.467d {+44d 28' 02"} (current),
                 +44.066d {+44d 03' 58"} (1950)
GRB_ERROR:       19.30 [deg radius, statistical plus systematic]
GRB_INTEN:       162 [cnts/sec]
DATA_SIGNIF:     8.00 [sigma]
INTEG_TIME:      1.024 [sec]
GRB_DATE:        20672 TJD;   363 DOY;   24/12/28
GRB_TIME:        14230.17 SOD {03:57:10.17} UT
GRB_PHI:          50.00 [deg]
GRB_THETA:        30.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO:      1.39
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      92%  GRB
2nd_MOST_LIKELY:   5%  Distant Particles
DETECTORS:       1,1,0, 0,0,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       277.52d {+18h 30m 05s}  -23.26d {-23d 15' 18"}
SUN_DIST:         91.01 [deg]   Sun_angle= -4.4 [hr] (East of Sun)
MOON_POSTN:      241.32d {+16h 05m 17s}  -25.30d {-25d 18' 08"}
MOON_DIST:       116.35 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      102.09,-13.82 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:        8.02, 46.03 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn241228165/quicklook/glg_lc_medres34_bn241228165.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 228.57,24.17 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(5.0<100sec) coincident with the SWIFT_BAT event (trignum=1277277).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 28 Dec 24 03:57:58 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      57
TRIGGER_NUM:     757051035
GRB_RA:          337.030d {+22h 28m 07s} (J2000),
                 337.289d {+22h 29m 09s} (current),
                 336.514d {+22h 26m 03s} (1950)
GRB_DEC:         +48.670d {+48d 40' 12"} (J2000),
                 +48.798d {+48d 47' 54"} (current),
                 +48.414d {+48d 24' 51"} (1950)
GRB_ERROR:       8.48 [deg radius, statistical only]
DATA_SIGNIF:     9.80 [sigma]
DATA_INTERVAL:   1.024 [sec]
GRB_DATE:        20672 TJD;   363 DOY;   24/12/28
GRB_TIME:        14230.17 SOD {03:57:10.17} UT
GRB_PHI:          38.00 [deg]
GRB_THETA:        27.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4173 (Gnd S/W Version number)
SUN_POSTN:       277.52d {+18h 30m 05s}  -23.26d {-23d 15' 18"}
SUN_DIST:         89.56 [deg]   Sun_angle= -4.0 [hr] (East of Sun)
MOON_POSTN:      241.32d {+16h 05m 18s}  -25.30d {-25d 18' 11"}
MOON_DIST:       112.55 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:       99.97, -7.71 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:        5.85, 52.32 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn241228165/quicklook/glg_lc_medres34_bn241228165.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_757051035.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.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(5.0<100sec) coincident with the SWIFT_BAT event (trignum=1277277).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 28 Dec 24 03:58:40 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      0
TRIGGER_NUM:     757051035
GRB_RA:          341.020d {+22h 44m 05s} (J2000),
                 341.321d {+22h 45m 17s} (current),
                 340.417d {+22h 41m 40s} (1950)
GRB_DEC:         +22.560d {+22d 33' 36"} (J2000),
                 +22.692d {+22d 41' 30"} (current),
                 +22.297d {+22d 17' 50"} (1950)
GRB_ERROR:       2.83 [deg radius, statistical only]
DATA_SIGNIF:     28.60 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        20672 TJD;   363 DOY;   24/12/28
GRB_TIME:        14230.17 SOD {03:57:10.17} UT
GRB_PHI:          52.00 [deg]
GRB_THETA:        52.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       277.52d {+18h 30m 05s}  -23.26d {-23d 15' 18"}
SUN_DIST:         77.18 [deg]   Sun_angle= -4.3 [hr] (East of Sun)
MOON_POSTN:      241.33d {+16h 05m 19s}  -25.30d {-25d 18' 16"}
MOON_DIST:       108.03 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:       88.06,-31.55 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      351.99, 28.13 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn241228165/quicklook/glg_lc_medres34_bn241228165.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_757051035.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(5.0<100sec) coincident with the SWIFT_BAT event (trignum=1277277).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 28 Dec 24 03:58:49 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      1
TRIGGER_NUM:     757051035
GRB_RA:          340.730d {+22h 42m 55s} (J2000),
                 341.033d {+22h 44m 08s} (current),
                 340.124d {+22h 40m 30s} (1950)
GRB_DEC:         +20.620d {+20d 37' 12"} (J2000),
                 +20.751d {+20d 45' 05"} (current),
                 +20.358d {+20d 21' 28"} (1950)
GRB_ERROR:       1.89 [deg radius, statistical only]
DATA_SIGNIF:     46.10 [sigma]
DATA_INTERVAL:   6.144 [sec]
GRB_DATE:        20672 TJD;   363 DOY;   24/12/28
GRB_TIME:        14230.17 SOD {03:57:10.17} UT
GRB_PHI:          52.00 [deg]
GRB_THETA:        54.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       277.52d {+18h 30m 05s}  -23.26d {-23d 15' 18"}
SUN_DIST:         75.92 [deg]   Sun_angle= -4.2 [hr] (East of Sun)
MOON_POSTN:      241.33d {+16h 05m 20s}  -25.30d {-25d 18' 17"}
MOON_DIST:       107.09 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:       86.52,-33.01 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      350.79, 26.49 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn241228165/quicklook/glg_lc_medres34_bn241228165.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_757051035.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(5.0<100sec) coincident with the SWIFT_BAT event (trignum=1277277).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 28 Dec 24 03:59:13 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      2
TRIGGER_NUM:     757051035
GRB_RA:          341.920d {+22h 47m 41s} (J2000),
                 342.222d {+22h 48m 53s} (current),
                 341.316d {+22h 45m 16s} (1950)
GRB_DEC:         +22.530d {+22d 31' 48"} (J2000),
                 +22.662d {+22d 39' 45"} (current),
                 +22.266d {+22d 15' 57"} (1950)
GRB_ERROR:       1.84 [deg radius, statistical only]
DATA_SIGNIF:     44.30 [sigma]
DATA_INTERVAL:   9.216 [sec]
GRB_DATE:        20672 TJD;   363 DOY;   24/12/28
GRB_TIME:        14230.17 SOD {03:57:10.17} UT
GRB_PHI:          53.00 [deg]
GRB_THETA:        52.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       277.52d {+18h 30m 05s}  -23.26d {-23d 15' 18"}
SUN_DIST:         77.87 [deg]   Sun_angle= -4.3 [hr] (East of Sun)
MOON_POSTN:      241.34d {+16h 05m 21s}  -25.31d {-25d 18' 20"}
MOON_DIST:       108.80 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:       88.86,-32.03 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      352.82, 27.75 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn241228165/quicklook/glg_lc_medres34_bn241228165.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_757051035.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(5.0<100sec) coincident with the SWIFT_BAT event (trignum=1277277).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 28 Dec 24 03:59:08 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     1277277,   Seg_Num: 0
POINT_RA:        344.814d {+22h 59m 15s} (J2000)
POINT_DEC:       +18.598d {+18d 35' 51"} (J2000)
IMG_START_DATE:  20672 TJD;   363 DOY;   24/12/28
IMG_START_TIME:  14332.33 SOD {03:58:52.33} UT,   97.2 [sec] since BAT Trigger Time
COUNTS:          9    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        1    Max_iter_allowed= 4
ERROR_CODE:      1
COMMENTS:        SWIFT-XRT Nack Position.  
COMMENTS:        No source found in the image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 28 Dec 24 04:01:19 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1277277,   Seg_Num: 0
GRB_RA:          344.824d {+22h 59m 18s} (J2000),
                 345.132d {+23h 00m 32s} (current),
                 344.208d {+22h 56m 50s} (1950)
GRB_DEC:         +18.604d {+18d 36' 14"} (J2000),
                 +18.738d {+18d 44' 18"} (current),
                 +18.336d {+18d 20' 09"} (1950)
GRB_DATE:        20672 TJD;   363 DOY;   24/12/28
GRB_TIME:        14235.16 SOD {03:57:15.16} UT
TRIGGER_INDEX:   41
GRB_PHI:         -114.48 [deg]
GRB_THETA:        32.40 [deg]
DELTA_TIME:      45.00 [sec]
TRIGGER_DUR:     0.512 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     97.16 [sigma]
IMAGE_SIGNIF:    20.90 [sigma]
LC_URL:          sw01277277000msb.lc
SUN_POSTN:       277.52d {+18h 30m 06s}  -23.26d {-23d 15' 17"}
SUN_DIST:         78.19 [deg]   Sun_angle= -4.5 [hr] (East of Sun)
MOON_POSTN:      241.36d {+16h 05m 25s}  -25.31d {-25d 18' 35"}
MOON_DIST:       109.95 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:       89.13,-36.80 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      353.72, 23.04 [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 = 170.95,19.83 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 28 Dec 24 04:01:54 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1277277,   Seg_Num: 0
POINT_RA:        344.814d {+22h 59m 15s} (J2000)
POINT_DEC:       +18.598d {+18d 35' 51"} (J2000)
POINT_ROLL:      240.102d
IMG_START_DATE:  20672 TJD;   363 DOY;   24/12/28
IMG_START_TIME:  14336.09 SOD {03:58:56.09} UT,   100.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.154
N_STARS:         37
X_OFFSET:        416 [pixels]
Y_OFFSET:        591 [pixels]
X_MAX:           1375 [pixels]
Y_MAX:           1550 [pixels]
DET_THRESH:      15
PHOTO_THRESH:    8
SL_URL:          sw01277277000msufc0100.fits
SUN_POSTN:       277.52d {+18h 30m 06s}  -23.26d {-23d 15' 17"}
SUN_DIST:         78.18 [deg]   Sun_angle= -4.5 [hr] (East of Sun)
MOON_POSTN:      241.36d {+16h 05m 27s}  -25.31d {-25d 18' 39"}
MOON_DIST:       109.93 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:       89.12,-36.80 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      353.70, 23.04 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 28 Dec 24 04:02:02 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1277277,   Seg_Num: 0
POINT_RA:        344.814d {+22h 59m 15s} (J2000)
POINT_DEC:       +18.598d {+18d 35' 51"} (J2000)
POINT_ROLL:      240.102d
IMG_START_DATE:  20672 TJD;   363 DOY;   24/12/28
IMG_START_TIME:  14336.09 SOD {03:58:56.09} UT,   100.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.154
N_STARS:         37
X_OFFSET:        416 [pixels]
Y_OFFSET:        591 [pixels]
X_MAX:           1375 [pixels]
Y_MAX:           1550 [pixels]
DET_THRESH:      15
PHOTO_THRESH:    8
SL_URL:          sw01277277000msufc0100.fits
SUN_POSTN:       277.52d {+18h 30m 06s}  -23.26d {-23d 15' 17"}
SUN_DIST:         78.18 [deg]   Sun_angle= -4.5 [hr] (East of Sun)
MOON_POSTN:      241.36d {+16h 05m 27s}  -25.31d {-25d 18' 40"}
MOON_DIST:       109.93 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:       89.12,-36.80 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      353.70, 23.04 [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:     Sat 28 Dec 24 04:10:21 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1277277,   Seg_Num: 0
POINT_RA:        344.816d {+22h 59m 16s} (J2000)
POINT_DEC:       +18.599d {+18d 35' 56"} (J2000)
POINT_ROLL:      240.102d
IMG_START_DATE:  20672 TJD;   363 DOY;   24/12/28
IMG_START_TIME:  14549.48 SOD {04:02:29.48} UT,   314.3 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.946
N_STARS:         55
X_OFFSET:        176 [pixels]
Y_OFFSET:        351 [pixels]
X_MAX:           1615 [pixels]
Y_MAX:           1790 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    4
SL_URL:          sw01277277000msufc0314.fits
SUN_POSTN:       277.53d {+18h 30m 07s}  -23.25d {-23d 15' 16"}
SUN_DIST:         78.18 [deg]   Sun_angle= -4.5 [hr] (East of Sun)
MOON_POSTN:      241.44d {+16h 05m 46s}  -25.33d {-25d 19' 39"}
MOON_DIST:       109.87 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:       89.12,-36.80 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      353.71, 23.04 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 28 Dec 24 04:10:29 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1277277,   Seg_Num: 0
POINT_RA:        344.816d {+22h 59m 16s} (J2000)
POINT_DEC:       +18.599d {+18d 35' 56"} (J2000)
POINT_ROLL:      240.102d
IMG_START_DATE:  20672 TJD;   363 DOY;   24/12/28
IMG_START_TIME:  14549.48 SOD {04:02:29.48} UT,   314.3 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.946
N_STARS:         55
X_OFFSET:        176 [pixels]
Y_OFFSET:        351 [pixels]
X_MAX:           1615 [pixels]
Y_MAX:           1790 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    4
SL_URL:          sw01277277000msufc0314.fits
SUN_POSTN:       277.53d {+18h 30m 07s}  -23.25d {-23d 15' 16"}
SUN_DIST:         78.18 [deg]   Sun_angle= -4.5 [hr] (East of Sun)
MOON_POSTN:      241.44d {+16h 05m 46s}  -25.33d {-25d 19' 40"}
MOON_DIST:       109.87 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:       89.12,-36.80 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      353.71, 23.04 [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:     Sat 28 Dec 24 04:03:17 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1277277,   Seg_Num: 0
POINT_RA:        344.814d {+22h 59m 15s} (J2000)
POINT_DEC:       +18.598d {+18d 35' 51"} (J2000)
ROLL:            240.102d
IMG_START_DATE:  20672 TJD;   363 DOY;   24/12/28
IMG_START_TIME:  14336.09 SOD {03:58:56.09} UT,   100.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     757051170
X_OFFSET:        735 [pixels]
Y_OFFSET:        910 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       895
Y_GRB_POS:       1070
BINNING_INDEX:   1
IM_URL:          sw01277277000msuni0135.fits
SUN_POSTN:       277.52d {+18h 30m 06s}  -23.26d {-23d 15' 17"}
SUN_DIST:         78.18 [deg]   Sun_angle= -4.5 [hr] (East of Sun)
MOON_POSTN:      241.37d {+16h 05m 30s}  -25.31d {-25d 18' 49"}
MOON_DIST:       109.92 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:       89.12,-36.80 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      353.70, 23.04 [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:     Sat 28 Dec 24 04:11:14 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     1277277,   Seg_Num: 0
GRB_RA:          344.8017d {+22h 59m 12.40s} (J2000),
                 345.1097d {+23h 00m 26.32s} (current),
                 344.1860d {+22h 56m 44.65s} (1950)
GRB_DEC:         +18.6100d {+18d 36' 35.9"} (J2000),
                 +18.7444d {+18d 44' 39.6"} (current),
                 +18.3417d {+18d 20' 30.2"} (1950)
GRB_ERROR:       1.9 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  20672 TJD;   363 DOY;   24/12/28
IMG_START_TIME:  14420.00 SOD {04:00:20.00} UT,   184.8 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       277.53d {+18h 30m 07s}  -23.25d {-23d 15' 16"}
SUN_DIST:         78.17 [deg]   Sun_angle= -4.5 [hr] (East of Sun)
MOON_POSTN:      241.45d {+16h 05m 47s}  -25.33d {-25d 19' 46"}
MOON_DIST:       109.86 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:       89.11,-36.78 [deg] galactic lon,lat of the burst
ECL_COORDS:      353.70, 23.06 [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 http://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 0.11% < P(seren) < 0.58%.

GCN Circular #38681
V. D'Elia (SSDC & INAF-OAR), A. D'Ai (INAF-IASFPA), S. Dichiara (PSU), R. Gupta (NASA GSFC) and N. P. M. Kuin (UCL-MSSL) report on behalf of the Neil Gehrels Swift Observatory Team:
At 03:57:15 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 241228A (trigger=1277277). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 344.824, +18.604 which is
```
   RA(J2000) = 22h 59m 18s
   Dec(J2000) = +18d 36' 14"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multipeak structure with a duration of about 20 sec. The peak count rate was ~11085 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 03:58:52.3 UT, 97.2 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 344.80173, 18.61005 which is equivalent to:
```
   RA(J2000)  = 22h 59m 12.42s
   Dec(J2000) = +18d 36' 36.2"
```
with an uncertainty of 1.9 arcseconds (radius, 90% containment). This location is 79 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. We cannot determine whether the source is fading at the present time.
A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (6.67 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 6.2 (+4.07/-3.30) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 100 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 19.6 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 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.091.
Burst Advocate for this burst is V. D'Elia (valerio.delia AT ssdc.asi.it). 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 NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 28 Dec 24 04:17:38 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1277277,   Seg_Num: 0
POINT_RA:        344.815d {+22h 59m 16s} (J2000)
POINT_DEC:       +18.599d {+18d 35' 56"} (J2000)
POINT_ROLL:      240.102d
IMG_START_DATE:  20672 TJD;   363 DOY;   24/12/28
IMG_START_TIME:  15103.01 SOD {04:11:43.01} UT,   867.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.771
N_STARS:         89
X_OFFSET:        176 [pixels]
Y_OFFSET:        351 [pixels]
X_MAX:           1615 [pixels]
Y_MAX:           1790 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    7
SL_URL:          sw01277277000msufc0867.fits
SUN_POSTN:       277.54d {+18h 30m 09s}  -23.25d {-23d 15' 15"}
SUN_DIST:         78.17 [deg]   Sun_angle= -4.5 [hr] (East of Sun)
MOON_POSTN:      241.51d {+16h 06m 02s}  -25.34d {-25d 20' 32"}
MOON_DIST:       109.81 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:       89.12,-36.80 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      353.71, 23.04 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 28 Dec 24 04:17:51 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1277277,   Seg_Num: 0
POINT_RA:        344.815d {+22h 59m 16s} (J2000)
POINT_DEC:       +18.599d {+18d 35' 56"} (J2000)
POINT_ROLL:      240.102d
IMG_START_DATE:  20672 TJD;   363 DOY;   24/12/28
IMG_START_TIME:  15103.01 SOD {04:11:43.01} UT,   867.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.771
N_STARS:         89
X_OFFSET:        176 [pixels]
Y_OFFSET:        351 [pixels]
X_MAX:           1615 [pixels]
Y_MAX:           1790 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    7
SL_URL:          sw01277277000msufc0867.fits
SUN_POSTN:       277.54d {+18h 30m 09s}  -23.25d {-23d 15' 15"}
SUN_DIST:         78.17 [deg]   Sun_angle= -4.5 [hr] (East of Sun)
MOON_POSTN:      241.51d {+16h 06m 02s}  -25.34d {-25d 20' 33"}
MOON_DIST:       109.81 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:       89.12,-36.80 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      353.71, 23.04 [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:     Sat 28 Dec 24 04:11:42 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1277277,   Seg_Num: 0
POINT_RA:        344.816d {+22h 59m 16s} (J2000)
POINT_DEC:       +18.599d {+18d 35' 56"} (J2000)
ROLL:            240.102d
IMG_START_DATE:  20672 TJD;   363 DOY;   24/12/28
IMG_START_TIME:  14549.48 SOD {04:02:29.48} UT,   314.3 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     757051384
X_OFFSET:        735 [pixels]
Y_OFFSET:        910 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       895
Y_GRB_POS:       1070
BINNING_INDEX:   1
IM_URL:          sw01277277000msuni0349.fits
SUN_POSTN:       277.53d {+18h 30m 07s}  -23.25d {-23d 15' 16"}
SUN_DIST:         78.18 [deg]   Sun_angle= -4.5 [hr] (East of Sun)
MOON_POSTN:      241.45d {+16h 05m 49s}  -25.33d {-25d 19' 49"}
MOON_DIST:       109.86 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:       89.12,-36.80 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      353.71, 23.04 [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:     Sat 28 Dec 24 04:19:30 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1277277,   Seg_Num: 0
POINT_RA:        344.815d {+22h 59m 16s} (J2000)
POINT_DEC:       +18.599d {+18d 35' 56"} (J2000)
ROLL:            240.102d
IMG_START_DATE:  20672 TJD;   363 DOY;   24/12/28
IMG_START_TIME:  15103.01 SOD {04:11:43.01} UT,   867.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     757051937
X_OFFSET:        735 [pixels]
Y_OFFSET:        910 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       895
Y_GRB_POS:       1070
BINNING_INDEX:   1
IM_URL:          sw01277277000msuni0902.fits
SUN_POSTN:       277.54d {+18h 30m 09s}  -23.25d {-23d 15' 15"}
SUN_DIST:         78.17 [deg]   Sun_angle= -4.5 [hr] (East of Sun)
MOON_POSTN:      241.52d {+16h 06m 06s}  -25.35d {-25d 20' 45"}
MOON_DIST:       109.80 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:       89.12,-36.80 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      353.71, 23.04 [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 NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 28 Dec 24 04:11:49 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1277277,   Seg_Num: 0
POINT_RA:        344.816d {+22h 59m 16s} (J2000)
POINT_DEC:       +18.599d {+18d 35' 56"} (J2000)
ROLL:            240.102d
IMG_START_DATE:  20672 TJD;   363 DOY;   24/12/28
IMG_START_TIME:  14549.48 SOD {04:02:29.48} UT,   314.3 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     757051384
X_OFFSET:        735 [pixels]
Y_OFFSET:        910 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       895
Y_GRB_POS:       1070
BINNING_INDEX:   1
IM_URL:          sw01277277000msuni0349.fits
SUN_POSTN:       277.53d {+18h 30m 07s}  -23.25d {-23d 15' 16"}
SUN_DIST:         78.18 [deg]   Sun_angle= -4.5 [hr] (East of Sun)
MOON_POSTN:      241.45d {+16h 05m 49s}  -25.33d {-25d 19' 50"}
MOON_DIST:       109.86 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:       89.12,-36.80 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      353.71, 23.04 [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 NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 28 Dec 24 04:03:30 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1277277,   Seg_Num: 0
POINT_RA:        344.814d {+22h 59m 15s} (J2000)
POINT_DEC:       +18.598d {+18d 35' 51"} (J2000)
ROLL:            240.102d
IMG_START_DATE:  20672 TJD;   363 DOY;   24/12/28
IMG_START_TIME:  14336.09 SOD {03:58:56.09} UT,   100.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     757051170
X_OFFSET:        735 [pixels]
Y_OFFSET:        910 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       895
Y_GRB_POS:       1070
BINNING_INDEX:   1
IM_URL:          sw01277277000msuni0135.fits
SUN_POSTN:       277.52d {+18h 30m 06s}  -23.26d {-23d 15' 17"}
SUN_DIST:         78.18 [deg]   Sun_angle= -4.5 [hr] (East of Sun)
MOON_POSTN:      241.38d {+16h 05m 30s}  -25.31d {-25d 18' 50"}
MOON_DIST:       109.92 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:       89.12,-36.80 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      353.70, 23.04 [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 NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 28 Dec 24 04:04:13 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     1277277,   Seg_Num: 0
GRB_RA:          344.8007d {+22h 59m 12.16s} (J2000),
                 345.1087d {+23h 00m 26.08s} (current),
                 344.1850d {+22h 56m 44.41s} (1950)
GRB_DEC:         +18.6093d {+18d 36' 33.4"} (J2000),
                 +18.7437d {+18d 44' 37.1"} (current),
                 +18.3410d {+18d 20' 27.7"} (1950)
GRB_ERROR:       4.8 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  20672 TJD;   363 DOY;   24/12/28
IMG_START_TIME:  14420.00 SOD {04:00:20.00} UT,   184.8 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       277.53d {+18h 30m 06s}  -23.25d {-23d 15' 17"}
SUN_DIST:         78.18 [deg]   Sun_angle= -4.5 [hr] (East of Sun)
MOON_POSTN:      241.38d {+16h 05m 32s}  -25.32d {-25d 18' 55"}
MOON_DIST:       109.91 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:       89.11,-36.78 [deg] galactic lon,lat of the burst
ECL_COORDS:      353.70, 23.06 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
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 http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.11% < P(seren) < 0.58%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 28 Dec 24 04:19:16 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1277277,   Seg_Num: 0
POINT_RA:        344.815d {+22h 59m 16s} (J2000)
POINT_DEC:       +18.599d {+18d 35' 56"} (J2000)
ROLL:            240.102d
IMG_START_DATE:  20672 TJD;   363 DOY;   24/12/28
IMG_START_TIME:  15103.01 SOD {04:11:43.01} UT,   867.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     757051937
X_OFFSET:        735 [pixels]
Y_OFFSET:        910 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       895
Y_GRB_POS:       1070
BINNING_INDEX:   1
IM_URL:          sw01277277000msuni0902.fits
SUN_POSTN:       277.54d {+18h 30m 09s}  -23.25d {-23d 15' 15"}
SUN_DIST:         78.17 [deg]   Sun_angle= -4.5 [hr] (East of Sun)
MOON_POSTN:      241.52d {+16h 06m 05s}  -25.35d {-25d 20' 43"}
MOON_DIST:       109.80 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:       89.12,-36.80 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      353.71, 23.04 [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 Circular #38683
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team.
Using 1737 s of XRT Photon Counting mode data and 4 UVOT images for GRB 241228A, 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 = 344.80186, +18.61065 which is equivalent to:
```
RA (J2000): 22h 59m 12.45s
Dec (J2000): +18d 36' 38.3"
```
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 http://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 #38685
N. P. M. Kuin (UCL-MSSL) and V. D'Elia (SSDC & INAF-OAR)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 241228A 101 s after the BAT trigger (D'Elia et al., GCN Circ. 38681). No optical afterglow consistent with the XRT position in that circular was 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

white_FC           101          251          147         >21.0
u_FC               314          564          246         >19.8
white              101         1538          392         >21.3
v                  644         1416           97         >19.1
b                  570         1514           97         >19.8
u                  314         1489          324         >20.0
w1                 694         1465           78         >19.2
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.091 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #38686
C. Salvaggio (INAF-OAB), J.A. Kennea (PSU), D.N. Burrows (PSU), M. A. Williams (PSU), A.P. Beardmore (U. Leicester), J.P. Osborne (U. Leicester), M. Ferro (INAF-OAB), R. Brivio (INAF-OAB) and P.A. Evans report on behalf of the Swift-XRT team:
We have analysed 9.1 ks of XRT data for GRB 241228A, from 82 s to 28.8 ks after the BAT trigger. The data comprise 83 s in Windowed Timing (WT) mode (the first 8 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode.
The late-time light curve (from T0+4.8 ks) can be modelled with a power-law decay with a decay index of alpha=1.54 (+0.13, -0.12).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.00 (+0.18, -0.17). The best-fitting absorption column is 2.2 (+0.7, -0.6) x 10^21 cm^-2, in excess of the Galactic value of 6.7 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.86 (+0.15, -0.14) and a best-fitting absorption column of 3.6 (+0.8, -0.7) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.2 x 10^-11 (6.0 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     3.6 (+0.8, -0.7) x 10^21 cm^-2
Galactic foreground: 6.7 x 10^20 cm^-2
Excess significance: 6.9 sigma
Photon index:	     1.86 (+0.15, -0.14)
```
If the light curve continues to decay with a power-law decay index of 1.54, the count rate at T+24 hours will be 4.5 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.9 x 10^-13 (2.7 x 10^-13) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01277277.
This circular is an official product of the Swift-XRT team.
GCN Circular #38689
T. Mohan, V. Swain, 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 the GRB 241228A (D'Elia et al., GCN 38681) with the 0.7m GROWTH-India Telescope (GIT). Observation started at 2024-12-28T13:13:58 UT, about 9.27 hours after the trigger. We responded to the enhanced Swift-XRT coordinates (Evans et al., GCN 38683) and obtained multiple images of 360s in r' filter.
The obtained upper limit in our stacked image is:
```
| MJD (mid)   | Filter | Exposure (s) | Limiting Magnitude (AB) |
| ----------- | ------ | ------------ | ----------------------- |
| 60672.56537 | r'     | 4x360        | 20.8
```
The upper limit is consistent with Kuin et al., GCN 38685.
The magnitude 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 #38693
V.Lipunov, E.Gorbovskoy, N.Tiurina, P.Balanutsa, , D.Vlasenko, I.Panchenko, A.Kuznetsov, G.Antipov, A.Sankovich, A.Sosnovskij, Yu.Tselik, M.Gulyaev, 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. 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 241228A ( V. D'Elia et al., GCN 38681) errorbox 53242 sec after notice time and 53275 sec after trigger time at 2024-12-28 18:45:10 UT, with upper limit up to 16.7 mag. Observations started at twilight. The observations began at zenith distance = 72 deg. The sun altitude is -11.2 deg.
The galactic latitude b = -37 deg., longitude l = 90 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2724378
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

   53366 |         MASTER-SAAO |   C |   180 | 12.2 |        
   53565 |         MASTER-SAAO |   C |   180 | 16.4 |        
   53764 |         MASTER-SAAO |   C |   180 | 16.5 |        
   53964 |         MASTER-SAAO |   C |   180 | 16.6 |        
   54163 |         MASTER-SAAO |   C |   180 | 16.7 |        
   54364 |         MASTER-SAAO |   C |   180 | 16.5 |        
   54563 |         MASTER-SAAO |   C |   180 | 16.6 |        
   54763 |         MASTER-SAAO |   C |   180 | 16.5 |        
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
GCN Circular #38695
L. Scotton (UAH) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team:
"At 03:57:10.17 UT on 28 December 2024, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 241228A (trigger 757051035/241228165), which was also detected by Swift BAT (V. D'Elia et al. 2024, GCN 38681). The Fermi GBM on-ground location is consistent with the Swift BAT position.
The angle from the Fermi LAT boresight is 55 degrees.
The GBM light curve consists of a minor triggering episode followed by a two-peak episode, with a duration (T90) of about 8.3 s (50-300 keV). The time-averaged spectrum from T0-0.5 to T0+10.9 s is best fit by a Band function with Epeak = 66 +/- 3 keV, alpha = -0.68 +/- 0.08, and beta = -2.8 +/- 0.1.
The event fluence (10-1000 keV) in this time interval is (5.6 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+7.0 s in the 10-1000 keV band is 19.9 +/- 0.4 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 #38701
D. Sadaula (GSFC/UMBC), S. D. Barthelmy (GSFC), D’Elia (SSDC & INAF-OAR), R. Gupta (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), M. J. Moss (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC), T. Sakamoto (AGU) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+1101 sec from the recent telemetry downlink, we report further analysis of BAT GRB 241228A (trigger #1277277) (D'Elia et al., GCN Circ. 38681). The BAT ground-calculated position is RA, Dec = 344.810, 18.608 deg which is
```
   RA(J2000)  =  22h 59m 14.4s
   Dec(J2000) = +18d 36' 28.6"
```
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 39%.
The mask-weighted light curve shows several overlapping pulses that start at ~T-5 s and end at ~T+5 s. T90 (15-350 keV) is 8.06 +- 0.53 sec (estimated error including systematics).
The time-averaged spectrum from T-5.16 to T+4.71 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.90 +- 0.24, and Epeak of 61.0 +- 5.2 keV (chi squared 82.23 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 3.0 +- 0.1 x 10^-06 erg/cm2 and the 1-sec peak flux measured from T+1.94 sec in the 15-150 keV band is 13.1 +- 0.6 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/1277277
GCN Circular #38703
Z.P. Zhu (NAOC), J. T. Palmerio (CEA/Irfu), J. An, D. Xu (NAOC), D. B. Malesani (DAWN/NBI and Radboud Univ.), T. Pursimo (NOT) report on behalf of a large collaboration:
We observed the field of GRB 241228A detected by Swift (D'Elia et al., GCN 38681), using the ALFOSC instruments mounted on the Nordic Optical Telescope (NOT), with 3 x 300 s in the SDSS-r band and 5 x 200 s photometry in the SDSS-z band. Observations started at 21:10:46 UT on 2024-12-28, i.e. 0.72 day after the trigger.
No new source is detected within the Swift/XRT enhanced error circle (Evans et al., GCN 38683), being consistent with the previous reports (Kuin et al., GCN 38685; Mohan et al., GCN 38689; Lipunov et al., GCN 38693), down to the 5-sigma upper limits of r > 22.0 (AB) and z > 20.5 (AB), calibrated with nearby Pan-STARRS stars without Galactic extinction correction.
GCN Circular #38727
A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report:
The long-duration GRB 241228A (Swift-BAT detection: D'Elia et al., GCN 38681; Sadaula et al., GCN 38701; Fermi-GBM detection: Scotton & Meegan, GCN 38695) triggered Konus-Wind at T0=14233.924 s UT (03:57:13.924).
The burst light curve shows a two-peak structure which starts at ~T0-0.2 s and has a total duration of ~5.1 s. The emission is seen up to ~2 MeV.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB241228_T14233/
As observed by Konus-Wind, the burst had a fluence of 3.35(-0.17,+0.18)x10^-6 erg/cm2, and a 64-ms peak flux, measured from T0+1.760 s, of 1.74(-0.01,+0.01)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst (measured from T0 to T0+8.448 s) is best fit in the 20 keV - 10 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.88(-0.24,+0.26) and Ep = 75(-5,+5) keV (chi2 = 96/81 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.7 (chi2 = 96/80 dof).
All the quoted errors are at the 68% confidence level. All the quoted values are preliminary.
GCN Circular #38815
Amit K. Ror, Anshika Gupta, Pranshu, Shashi B. Pandey, Kuntal Mishra (ARIES) report:
We observed the field of GRB 241228A detected by Swift (Swift Observatory Team, D'Elia et al. 2024, GCN 38681) with the 1.3m Devasthal Fast Optical Telescope (DFOT), located at the Devasthal Observatory of the Aryabhatta Research Institute of Observational Sciences (ARIES), India. The observations were started on 2024-12-30 at 13:16:07 UT, i.e., ~ 2.38 days after the Swift-BAT trigger. We have taken multiple frames with an exposure time of 300 s in the R filter. We stacked the images after the alignment. We could not detect the optical emission reported by Volnova et al. (2024, GCN 38709) in our stacked image within the error box enhanced Swift-XRT position (GCN 38683). We obtain the following 3-sigma upper limit in the stacked image:
Date Start_UT T_start-T0 (days) Filter Exp time (s) Magnitude
=========================================================
2024-12-30 13:16:07 ~ 2.38 R 300s*12 >21.2
The non-detection of the burst is consistent with the upper limits reported by Kuin et al. 2024, GCN 38685; Mohan et al. 2024, GCN 38689; Lipunov et al. 2024, GCN 38693; Zhu et al. 2024, GCN 38703.
The magnitude is not corrected for the Galactic extinction in the direction of the burst. Photometric calibration is performed using the standard stars from the USNO-B1.0 catalogue. This circular may be cited.
GCN Circular #39684
R. Querrard (UVI), P. Gokuldass (ERAU), N. Orange (OrangeWave Innovative Science, LLC), B. Gendre (UVI), D. Morris (NASA), T. Lombardi (Eckerd College), F. George (ERAU), D. Smith (UVI), K. Smith (UVI), C. Watson (UVI) report:
We observed the field of GRB241228A (D'Elia et al., GCN 38681) with the 0.5m Virgin Island Robotic Telescope (VIRT) at the University of the Virgin Islands' Etelman Observatory on 2024-12-28 starting at 03:57:15 UT (T-mid ~ T0 + 43.91 hrs). We performed a series of exposures in an R filter with a total exposure of 2060s. The weather conditions were partly cloudy during the hours of observation with an average airmass of 1.68.
We do not detect any source within the enhanced XRT position (Evans et al. GCN 38683). This non-detection is consistent with reported upper limits (Kuin et al., GCN 38685; Mohan et al., GCN 38689; Lipunov et al., GCN 38693; Zhu et al., GCN 38703; Volnova et al., GCN 38709; and Ror et al., GCN 38815). We report the following 3-sigma upper limit:
```
T_mid                ||Exposure   ||Filter   ||Limit 
T+43.91 h            || 2060 s    || R       || > 20.4
```
The limit is estimated from comparison to nearby USNO B1 stars and is not corrected for Galactic extinction.
We acknowledge financial support from NASA EPSCoR award 80NNSC22M0063, NSF PAARE award 2319415, and NASA EPSCoR award 80NSSC24M0112. This message can be cited.

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Jochen Greiner, last update: 12-Mar-2025 [Disclaimer]