Gamma-ray Burst 240912A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 12 Sep 24 01:46:52 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1253910,   Seg_Num: 0
GRB_RA:          124.633d {+08h 18m 32s} (J2000),
                 125.026d {+08h 20m 06s} (current),
                 123.837d {+08h 15m 21s} (1950)
GRB_DEC:         +33.995d {+33d 59' 42"} (J2000),
                 +33.916d {+33d 54' 59"} (current),
                 +34.152d {+34d 09' 06"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       1479 [cnts]    Image_Peak=111 [image_cnts]
TRIGGER_DUR:     0.512 [sec] 
TRIGGER_INDEX:   124     E_range: 25-100 keV
BKG_INTEN:       16327 [cnts]
BKG_TIME:        6381.84 SOD {01:46:21.84} UT
BKG_DUR:         8 [sec]
GRB_DATE:        20565 TJD;   256 DOY;   24/09/12
GRB_TIME:        6399.18 SOD {01:46:39.18} UT
GRB_PHI:         -165.32 [deg]
GRB_THETA:        29.08 [deg]
SOLN_STATUS:     0x20000003
RATE_SIGNIF:     13.00 [sigma]
IMAGE_SIGNIF:    7.78 [sigma]
MERIT_PARAMS:     +1  +0  +0  -1  +2  -2  +0  +0 -61  +0 
SUN_POSTN:       170.63d {+11h 22m 30s}   +4.04d {+04d 02' 18"}
SUN_DIST:         51.80 [deg]   Sun_angle= 3.0 [hr] (West of Sun)
MOON_POSTN:      269.39d {+17h 57m 35s}  -28.71d {-28d 42' 39"}
MOON_DIST:       149.27 [deg]
MOON_ILLUM:      58 [%]
GAL_COORDS:      188.03, 31.92 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      119.05, 13.98 [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 = 76.76,0.94 [deg].  
COMMENTS:           
COMMENTS:        NOTE: This BAT event is temporally(1.0<100sec) coincident with the FERMI_GBM event (trignum=747798405).

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 12 Sep 24 01:47:00 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      47
TRIGGER_NUM:     747798405
GRB_RA:          117.483d {+07h 49m 56s} (J2000),
                 117.856d {+07h 51m 25s} (current),
                 116.728d {+07h 46m 55s} (1950)
GRB_DEC:         +24.833d {+24d 49' 60"} (J2000),
                 +24.769d {+24d 46' 10"} (current),
                 +24.960d {+24d 57' 37"} (1950)
GRB_ERROR:       25.07 [deg radius, statistical plus systematic]
GRB_INTEN:       72 [cnts/sec]
DATA_SIGNIF:     7.10 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        20565 TJD;   256 DOY;   24/09/12
GRB_TIME:        6400.59 SOD {01:46:40.59} UT
GRB_PHI:          52.00 [deg]
GRB_THETA:        60.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      1.12
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      93%  GRB
2nd_MOST_LIKELY:   4%  Solar Flare
DETECTORS:       1,1,1, 0,0,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       170.63d {+11h 22m 30s}   +4.04d {+04d 02' 18"}
SUN_DIST:         54.72 [deg]   Sun_angle= 3.5 [hr] (West of Sun)
MOON_POSTN:      269.40d {+17h 57m 35s}  -28.71d {-28d 42' 39"}
MOON_DIST:       154.34 [deg]
MOON_ILLUM:      58 [%]
GAL_COORDS:      195.88, 23.29 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      114.82,  3.73 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240912074/quicklook/glg_lc_medres34_bn240912074.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 83.07,20.28 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(1.0<100sec) coincident with the SWIFT_BAT event (trignum=1253910).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 12 Sep 24 01:47:18 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      57
TRIGGER_NUM:     747798405
GRB_RA:          111.070d {+07h 24m 17s} (J2000),
                 111.457d {+07h 25m 50s} (current),
                 110.286d {+07h 21m 09s} (1950)
GRB_DEC:         +28.850d {+28d 51' 00"} (J2000),
                 +28.800d {+28d 48' 00"} (current),
                 +28.948d {+28d 56' 54"} (1950)
GRB_ERROR:       10.59 [deg radius, statistical only]
DATA_SIGNIF:     8.50 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        20565 TJD;   256 DOY;   24/09/12
GRB_TIME:        6400.59 SOD {01:46:40.59} UT
GRB_PHI:          60.00 [deg]
GRB_THETA:        61.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4173 (Gnd S/W Version number)
SUN_POSTN:       170.63d {+11h 22m 30s}   +4.04d {+04d 02' 17"}
SUN_DIST:         61.19 [deg]   Sun_angle= 3.9 [hr] (West of Sun)
MOON_POSTN:      269.40d {+17h 57m 36s}  -28.71d {-28d 42' 39"}
MOON_DIST:       160.69 [deg]
MOON_ILLUM:      58 [%]
GAL_COORDS:      189.69, 19.35 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      108.49,  6.75 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240912074/quicklook/glg_lc_medres34_bn240912074.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_747798405.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(1.0<100sec) coincident with the SWIFT_BAT event (trignum=1253910).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 12 Sep 24 01:47:26 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      68
TRIGGER_NUM:     747798405
GRB_RA:          107.367d {+07h 09m 28s} (J2000),
                 107.756d {+07h 11m 01s} (current),
                 106.578d {+07h 06m 19s} (1950)
GRB_DEC:         +29.067d {+29d 04' 00"} (J2000),
                 +29.025d {+29d 01' 31"} (current),
                 +29.148d {+29d 08' 53"} (1950)
GRB_ERROR:       12.10 [deg radius, statistical plus systematic]
GRB_INTEN:       101 [cnts/sec]
DATA_SIGNIF:     10.30 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        20565 TJD;   256 DOY;   24/09/12
GRB_TIME:        6400.59 SOD {01:46:40.59} UT
GRB_PHI:          63.98 [deg]
GRB_THETA:        60.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      1.39
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      96%  GRB
2nd_MOST_LIKELY:   1%  Generic SGR
DETECTORS:       1,1,1, 0,0,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       170.63d {+11h 22m 30s}   +4.04d {+04d 02' 17"}
SUN_DIST:         64.41 [deg]   Sun_angle= 4.2 [hr] (West of Sun)
MOON_POSTN:      269.40d {+17h 57m 36s}  -28.71d {-28d 42' 39"}
MOON_DIST:       163.94 [deg]
MOON_ILLUM:      58 [%]
GAL_COORDS:      188.22, 16.42 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      105.22,  6.54 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240912074/quicklook/glg_lc_medres34_bn240912074.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 83.07,20.28 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(1.0<100sec) coincident with the SWIFT_BAT event (trignum=1253910).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 12 Sep 24 01:47:59 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      91
TRIGGER_NUM:     747798405
GRB_RA:          118.700d {+07h 54m 48s} (J2000),
                 119.087d {+07h 56m 21s} (current),
                 117.915d {+07h 51m 40s} (1950)
GRB_DEC:         +30.417d {+30d 25' 00"} (J2000),
                 +30.350d {+30d 21' 01"} (current),
                 +30.549d {+30d 32' 55"} (1950)
GRB_ERROR:       9.68 [deg radius, statistical plus systematic]
GRB_INTEN:       241 [cnts/sec]
DATA_SIGNIF:     17.30 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        20565 TJD;   256 DOY;   24/09/12
GRB_TIME:        6400.59 SOD {01:46:40.59} UT
GRB_PHI:          55.00 [deg]
GRB_THETA:        65.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      1.68
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      77%  GRB
2nd_MOST_LIKELY:  12%  Generic SGR
DETECTORS:       1,1,1, 0,0,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       170.63d {+11h 22m 30s}   +4.04d {+04d 02' 17"}
SUN_DIST:         55.18 [deg]   Sun_angle= 3.4 [hr] (West of Sun)
MOON_POSTN:      269.41d {+17h 57m 37s}  -28.71d {-28d 42' 39"}
MOON_DIST:       154.20 [deg]
MOON_ILLUM:      58 [%]
GAL_COORDS:      190.45, 26.13 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      114.82,  9.42 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240912074/quicklook/glg_lc_medres34_bn240912074.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 83.07,20.28 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(1.0<100sec) coincident with the SWIFT_BAT event (trignum=1253910).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 12 Sep 24 01:48:14 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      0
TRIGGER_NUM:     747798405
GRB_RA:          123.780d {+08h 15m 07s} (J2000),
                 124.168d {+08h 16m 40s} (current),
                 122.994d {+08h 11m 58s} (1950)
GRB_DEC:         +32.010d {+32d 00' 36"} (J2000),
                 +31.933d {+31d 55' 59"} (current),
                 +32.163d {+32d 09' 48"} (1950)
GRB_ERROR:       6.42 [deg radius, statistical only]
DATA_SIGNIF:     12.10 [sigma]
DATA_INTERVAL:   9.216 [sec]
GRB_DATE:        20565 TJD;   256 DOY;   24/09/12
GRB_TIME:        6400.59 SOD {01:46:40.59} UT
GRB_PHI:          51.00 [deg]
GRB_THETA:        69.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       170.63d {+11h 22m 30s}   +4.04d {+04d 02' 16"}
SUN_DIST:         51.65 [deg]   Sun_angle= 3.1 [hr] (West of Sun)
MOON_POSTN:      269.41d {+17h 57m 38s}  -28.71d {-28d 42' 39"}
MOON_DIST:       149.95 [deg]
MOON_ILLUM:      58 [%]
GAL_COORDS:      190.09, 30.74 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      118.80, 11.89 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240912074/quicklook/glg_lc_medres34_bn240912074.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_747798405.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        This is likely a Long GRB.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file will not be created/available until ~15 min after the trigger.  
COMMENTS:        The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(1.0<100sec) coincident with the SWIFT_BAT event (trignum=1253910).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 12 Sep 24 01:48:08 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      94
TRIGGER_NUM:     747798405
GRB_RA:          108.150d {+07h 12m 36s} (J2000),
                 108.538d {+07h 14m 09s} (current),
                 107.363d {+07h 09m 27s} (1950)
GRB_DEC:         +28.833d {+28d 49' 60"} (J2000),
                 +28.790d {+28d 47' 24"} (current),
                 +28.918d {+28d 55' 06"} (1950)
GRB_ERROR:       4.87 [deg radius, statistical plus systematic]
GRB_INTEN:       1126 [cnts/sec]
DATA_SIGNIF:     116.80 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        20565 TJD;   256 DOY;   24/09/12
GRB_TIME:        6400.59 SOD {01:46:40.59} UT
GRB_PHI:          63.98 [deg]
GRB_THETA:        60.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      1.00
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      97%  GRB
2nd_MOST_LIKELY:   1%  Generic Transient
DETECTORS:       1,1,1, 0,0,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       170.63d {+11h 22m 30s}   +4.04d {+04d 02' 16"}
SUN_DIST:         63.70 [deg]   Sun_angle= 4.1 [hr] (West of Sun)
MOON_POSTN:      269.41d {+17h 57m 38s}  -28.71d {-28d 42' 39"}
MOON_DIST:       163.25 [deg]
MOON_ILLUM:      58 [%]
GAL_COORDS:      188.71, 16.97 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      105.94,  6.39 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240912074/quicklook/glg_lc_medres34_bn240912074.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 83.07,20.28 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(1.0<100sec) coincident with the SWIFT_BAT event (trignum=1253910).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 12 Sep 24 01:48:28 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      1
TRIGGER_NUM:     747798405
GRB_RA:          120.130d {+08h 00m 31s} (J2000),
                 120.507d {+08h 02m 02s} (current),
                 119.366d {+07h 57m 28s} (1950)
GRB_DEC:         +26.960d {+26d 57' 36"} (J2000),
                 +26.891d {+26d 53' 26"} (current),
                 +27.098d {+27d 05' 53"} (1950)
GRB_ERROR:       4.91 [deg radius, statistical only]
DATA_SIGNIF:     14.30 [sigma]
DATA_INTERVAL:   13.312 [sec]
GRB_DATE:        20565 TJD;   256 DOY;   24/09/12
GRB_TIME:        6400.59 SOD {01:46:40.59} UT
GRB_PHI:          51.00 [deg]
GRB_THETA:        63.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       170.63d {+11h 22m 30s}   +4.04d {+04d 02' 16"}
SUN_DIST:         52.97 [deg]   Sun_angle= 3.3 [hr] (West of Sun)
MOON_POSTN:      269.41d {+17h 57m 38s}  -28.71d {-28d 42' 40"}
MOON_DIST:       152.51 [deg]
MOON_ILLUM:      58 [%]
GAL_COORDS:      194.55, 26.25 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      116.75,  6.28 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240912074/quicklook/glg_lc_medres34_bn240912074.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_747798405.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        This is likely a Long GRB.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file will not be created/available until ~15 min after the trigger.  
COMMENTS:        The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(1.0<100sec) coincident with the SWIFT_BAT event (trignum=1253910).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 12 Sep 24 01:56:04 UT
NOTICE_TYPE:     Fermi-GBM Final Position
RECORD_NUM:      0
TRIGGER_NUM:     747798405
GRB_RA:          153.130d {+10h 12m 31s} (J2000),
                 153.474d {+10h 13m 54s} (current),
                 152.433d {+10h 09m 44s} (1950)
GRB_DEC:         +23.770d {+23d 46' 12"} (J2000),
                 +23.647d {+23d 38' 50"} (current),
                 +24.018d {+24d 01' 03"} (1950)
GRB_ERROR:       4.16 [deg radius, statistical only]
GRB_DATE:        20565 TJD;   256 DOY;   24/09/12
GRB_TIME:        6400.59 SOD {01:46:40.59} UT
GRB_PHI:          26.00 [deg]
GRB_THETA:        81.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       170.63d {+11h 22m 31s}   +4.04d {+04d 02' 09"}
SUN_DIST:         25.67 [deg]   Sun_angle= 1.1 [hr] (West of Sun)
MOON_POSTN:      269.49d {+17h 57m 57s}  -28.71d {-28d 42' 43"}
MOON_DIST:       123.03 [deg]
MOON_ILLUM:      59 [%]
GAL_COORDS:      209.24, 54.11 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      146.53, 11.85 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240912074/quicklook/glg_lc_medres34_bn240912074.gif
LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240912074/quicklook/glg_locplot_all_bn240912074.png
COMMENTS:        Fermi-GBM Final Position.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file should be available by the time this FINAL notice is produced.  
COMMENTS:        This notice was generated completely by automated pipeline processing.  
COMMENTS:        This is likely a Long GRB.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(1.0<100sec) coincident with the SWIFT_BAT event (trignum=1253910).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 12 Sep 24 01:48:58 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     1253910,   Seg_Num: 0
GRB_RA:          124.6327d {+08h 18m 31.8s} (J2000),
                 125.0252d {+08h 20m 06.0s} (current),
                 123.8365d {+08h 15m 20.7s} (1950)
GRB_DEC:         +34.0001d {+34d 00' 00.3"} (J2000),
                 +33.9216d {+33d 55' 17.6"} (current),
                 +34.1567d {+34d 09' 24.2"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       105 [cnts]
IMG_START_DATE:  20565 TJD;   256 DOY;   24/09/12
IMG_START_TIME:  6505.20 SOD {01:48:25.20} UT,   106.0 [sec] since BAT Trigger Time
CENTROID_X:      328.87,  raw= 329  [pixels]
CENTROID_Y:      298.71,  raw= 299  [pixels]
ROLL:            114.64 [deg]
GAIN:            1
MODE:            2, Short Image mode
WAVEFORM:        134
EXPO_TIME:       0.10 [sec]
GRB_POS_XRT_Y:   1.45
GRB_POS_XRT_Z:   50.62
IMAGE_URL:       sw01253910000msxps_rw.img
SUN_POSTN:       170.63d {+11h 22m 30s}   +4.04d {+04d 02' 16"}
SUN_DIST:         51.80 [deg]   Sun_angle= 3.0 [hr] (West of Sun)
MOON_POSTN:      269.42d {+17h 57m 40s}  -28.71d {-28d 42' 40"}
MOON_DIST:       149.29 [deg]
MOON_ILLUM:      58 [%]
GAL_COORDS:      188.03, 31.92 [deg] galactic lon,lat of the burst
ECL_COORDS:      119.05, 13.99 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 12 Sep 24 01:49:00 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     1253910,   Seg_Num: 0
GRB_RA:          124.6327d {+08h 18m 31.8s} (J2000),
                 125.0252d {+08h 20m 06.0s} (current),
                 123.8365d {+08h 15m 20.7s} (1950)
GRB_DEC:         +34.0001d {+34d 00' 00.3"} (J2000),
                 +33.9216d {+33d 55' 17.6"} (current),
                 +34.1567d {+34d 09' 24.2"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       105 [cnts]
IMG_START_DATE:  20565 TJD;   256 DOY;   24/09/12
IMG_START_TIME:  6505.20 SOD {01:48:25.20} UT,   106.0 [sec] since BAT Trigger Time
CENTROID_X:      328.87,  raw= 329  [pixels]
CENTROID_Y:      298.71,  raw= 299  [pixels]
ROLL:            114.64 [deg]
GAIN:            1
MODE:            2, Short Image mode
WAVEFORM:        134
EXPO_TIME:       0.10 [sec]
GRB_POS_XRT_Y:   1.45
GRB_POS_XRT_Z:   50.62
IMAGE_URL:       sw01253910000msxps_rw.img
SUN_POSTN:       170.63d {+11h 22m 30s}   +4.04d {+04d 02' 16"}
SUN_DIST:         51.80 [deg]   Sun_angle= 3.0 [hr] (West of Sun)
MOON_POSTN:      269.42d {+17h 57m 40s}  -28.71d {-28d 42' 40"}
MOON_DIST:       149.29 [deg]
MOON_ILLUM:      58 [%]
GAL_COORDS:      188.03, 31.92 [deg] galactic lon,lat of the burst
ECL_COORDS:      119.05, 13.99 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 12 Sep 24 01:48:48 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     1253910,   Seg_Num: 0
GRB_RA:          124.6327d {+08h 18m 31.84s} (J2000),
                 125.0252d {+08h 20m 06.03s} (current),
                 123.8365d {+08h 15m 20.75s} (1950)
GRB_DEC:         +34.0001d {+34d 00' 00.3"} (J2000),
                 +33.9216d {+33d 55' 17.6"} (current),
                 +34.1567d {+34d 09' 24.2"} (1950)
GRB_ERROR:       4.9 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       8.64e-08 [erg/cm2/sec]
GRB_SIGNIF:      10.24 [sigma]
IMG_START_DATE:  20565 TJD;   256 DOY;   24/09/12
IMG_START_TIME:  6505.20 SOD {01:48:25.20} UT,   106.0 [sec] since BAT Trigger Time
TAM[0-3]:        327.59 237.10 261.49 243.89
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       170.63d {+11h 22m 30s}   +4.04d {+04d 02' 16"}
SUN_DIST:         51.80 [deg]   Sun_angle= 3.0 [hr] (West of Sun)
MOON_POSTN:      269.41d {+17h 57m 39s}  -28.71d {-28d 42' 40"}
MOON_DIST:       149.29 [deg]
MOON_ILLUM:      58 [%]
GAL_COORDS:      188.03, 31.92 [deg] galactic lon,lat of the burst
ECL_COORDS:      119.05, 13.99 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 0.31 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 12 Sep 24 01:51:12 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1253910,   Seg_Num: 0
GRB_RA:          124.633d {+08h 18m 32s} (J2000),
                 125.026d {+08h 20m 06s} (current),
                 123.837d {+08h 15m 21s} (1950)
GRB_DEC:         +33.995d {+33d 59' 42"} (J2000),
                 +33.916d {+33d 54' 59"} (current),
                 +34.152d {+34d 09' 06"} (1950)
GRB_DATE:        20565 TJD;   256 DOY;   24/09/12
GRB_TIME:        6399.18 SOD {01:46:39.18} UT
TRIGGER_INDEX:   124
GRB_PHI:         -165.32 [deg]
GRB_THETA:        29.08 [deg]
DELTA_TIME:      25.00 [sec]
TRIGGER_DUR:     0.512 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     13.00 [sigma]
IMAGE_SIGNIF:    7.78 [sigma]
LC_URL:          sw01253910000msb.lc
SUN_POSTN:       170.63d {+11h 22m 31s}   +4.04d {+04d 02' 14"}
SUN_DIST:         51.80 [deg]   Sun_angle= 3.0 [hr] (West of Sun)
MOON_POSTN:      269.44d {+17h 57m 45s}  -28.71d {-28d 42' 41"}
MOON_DIST:       149.31 [deg]
MOON_ILLUM:      59 [%]
GAL_COORDS:      188.03, 31.92 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      119.05, 13.98 [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 = 76.76,0.94 [deg].

GCN Circular #37465
The Fermi GBM team reports the detection of a likely LONG GRB
At 01:46:40 UT on 12 Sep 2024, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 240912A (trigger 747798405.59471 / 240912074).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 153.1, Dec = 23.8 (J2000 degrees, equivalent to J2000 10h 12m, 23d 48'), with a statistical uncertainty of 4.2 degrees.
The angle from the Fermi LAT boresight is 81.0 degrees.
The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240912074/quicklook/glg_skymap_all_bn240912074.png
The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240912074/quicklook/glg_healpix_all_bn240912074.fit
The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2024/bn240912074/quicklook/glg_lc_medres34_bn240912074.gif

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 12 Sep 24 01:58:51 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1253910,   Seg_Num: 0
POINT_RA:        124.648d {+08h 18m 35s} (J2000)
POINT_DEC:       +33.994d {+33d 59' 37"} (J2000)
POINT_ROLL:      114.643d
IMG_START_DATE:  20565 TJD;   256 DOY;   24/09/12
IMG_START_TIME:  6726.40 SOD {01:52:06.40} UT,   327.2 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.814
N_STARS:         29
X_OFFSET:        385 [pixels]
Y_OFFSET:        601 [pixels]
X_MAX:           1344 [pixels]
Y_MAX:           1560 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    6
SL_URL:          sw01253910000msufc0327.fits
SUN_POSTN:       170.63d {+11h 22m 32s}   +4.04d {+04d 02' 06"}
SUN_DIST:         51.79 [deg]   Sun_angle= 3.0 [hr] (West of Sun)
MOON_POSTN:      269.52d {+17h 58m 04s}  -28.71d {-28d 42' 44"}
MOON_DIST:       149.36 [deg]
MOON_ILLUM:      59 [%]
GAL_COORDS:      188.04, 31.93 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      119.06, 13.98 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 12 Sep 24 01:59:00 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1253910,   Seg_Num: 0
POINT_RA:        124.648d {+08h 18m 35s} (J2000)
POINT_DEC:       +33.994d {+33d 59' 37"} (J2000)
POINT_ROLL:      114.643d
IMG_START_DATE:  20565 TJD;   256 DOY;   24/09/12
IMG_START_TIME:  6726.40 SOD {01:52:06.40} UT,   327.2 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.814
N_STARS:         29
X_OFFSET:        385 [pixels]
Y_OFFSET:        601 [pixels]
X_MAX:           1344 [pixels]
Y_MAX:           1560 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    6
SL_URL:          sw01253910000msufc0327.fits
SUN_POSTN:       170.63d {+11h 22m 32s}   +4.04d {+04d 02' 06"}
SUN_DIST:         51.79 [deg]   Sun_angle= 3.0 [hr] (West of Sun)
MOON_POSTN:      269.52d {+17h 58m 04s}  -28.71d {-28d 42' 44"}
MOON_DIST:       149.36 [deg]
MOON_ILLUM:      59 [%]
GAL_COORDS:      188.04, 31.93 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      119.06, 13.98 [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:     Thu 12 Sep 24 02:00:12 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1253910,   Seg_Num: 0
POINT_RA:        124.648d {+08h 18m 35s} (J2000)
POINT_DEC:       +33.994d {+33d 59' 37"} (J2000)
ROLL:            114.643d
IMG_START_DATE:  20565 TJD;   256 DOY;   24/09/12
IMG_START_TIME:  6726.40 SOD {01:52:06.40} UT,   327.2 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     747798760
X_OFFSET:        705 [pixels]
Y_OFFSET:        921 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       865
Y_GRB_POS:       1081
BINNING_INDEX:   1
IM_URL:          sw01253910000msuni0362.fits
SUN_POSTN:       170.63d {+11h 22m 32s}   +4.03d {+04d 02' 05"}
SUN_DIST:         51.79 [deg]   Sun_angle= 3.0 [hr] (West of Sun)
MOON_POSTN:      269.53d {+17h 58m 07s}  -28.71d {-28d 42' 44"}
MOON_DIST:       149.37 [deg]
MOON_ILLUM:      59 [%]
GAL_COORDS:      188.04, 31.93 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      119.06, 13.98 [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:     Thu 12 Sep 24 02:00:28 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1253910,   Seg_Num: 0
POINT_RA:        124.648d {+08h 18m 35s} (J2000)
POINT_DEC:       +33.994d {+33d 59' 37"} (J2000)
ROLL:            114.643d
IMG_START_DATE:  20565 TJD;   256 DOY;   24/09/12
IMG_START_TIME:  6726.40 SOD {01:52:06.40} UT,   327.2 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     747798760
X_OFFSET:        705 [pixels]
Y_OFFSET:        921 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       865
Y_GRB_POS:       1081
BINNING_INDEX:   1
IM_URL:          sw01253910000msuni0362.fits
SUN_POSTN:       170.63d {+11h 22m 32s}   +4.03d {+04d 02' 05"}
SUN_DIST:         51.79 [deg]   Sun_angle= 3.0 [hr] (West of Sun)
MOON_POSTN:      269.53d {+17h 58m 08s}  -28.71d {-28d 42' 45"}
MOON_DIST:       149.38 [deg]
MOON_ILLUM:      59 [%]
GAL_COORDS:      188.04, 31.93 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      119.06, 13.98 [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 NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 12 Sep 24 02:05:17 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1253910,   Seg_Num: 0
POINT_RA:        124.648d {+08h 18m 35s} (J2000)
POINT_DEC:       +33.994d {+33d 59' 37"} (J2000)
POINT_ROLL:      114.642d
IMG_START_DATE:  20565 TJD;   256 DOY;   24/09/12
IMG_START_TIME:  7280.11 SOD {02:01:20.11} UT,   880.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        7.179
N_STARS:         85
X_OFFSET:        145 [pixels]
Y_OFFSET:        361 [pixels]
X_MAX:           1584 [pixels]
Y_MAX:           1800 [pixels]
DET_THRESH:      23
PHOTO_THRESH:    14
SL_URL:          sw01253910000msufc0880.fits
SUN_POSTN:       170.64d {+11h 22m 33s}   +4.03d {+04d 02' 00"}
SUN_DIST:         51.80 [deg]   Sun_angle= 3.0 [hr] (West of Sun)
MOON_POSTN:      269.58d {+17h 58m 20s}  -28.71d {-28d 42' 46"}
MOON_DIST:       149.42 [deg]
MOON_ILLUM:      59 [%]
GAL_COORDS:      188.04, 31.93 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      119.06, 13.98 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 12 Sep 24 02:05:31 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1253910,   Seg_Num: 0
POINT_RA:        124.648d {+08h 18m 35s} (J2000)
POINT_DEC:       +33.994d {+33d 59' 37"} (J2000)
POINT_ROLL:      114.642d
IMG_START_DATE:  20565 TJD;   256 DOY;   24/09/12
IMG_START_TIME:  7280.11 SOD {02:01:20.11} UT,   880.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        7.179
N_STARS:         85
X_OFFSET:        145 [pixels]
Y_OFFSET:        361 [pixels]
X_MAX:           1584 [pixels]
Y_MAX:           1800 [pixels]
DET_THRESH:      23
PHOTO_THRESH:    14
SL_URL:          sw01253910000msufc0880.fits
SUN_POSTN:       170.64d {+11h 22m 33s}   +4.03d {+04d 01' 60"}
SUN_DIST:         51.80 [deg]   Sun_angle= 3.0 [hr] (West of Sun)
MOON_POSTN:      269.58d {+17h 58m 20s}  -28.71d {-28d 42' 47"}
MOON_DIST:       149.42 [deg]
MOON_ILLUM:      59 [%]
GAL_COORDS:      188.04, 31.93 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      119.06, 13.98 [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:     Thu 12 Sep 24 02:08:19 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1253910,   Seg_Num: 0
POINT_RA:          0.000d {+00h 00m 00s} (J2000)
POINT_DEC:        +0.000d {+00d 00' 00"} (J2000)
ROLL:            33.994d
IMG_START_DATE:  20565 TJD;   256 DOY;   24/09/12
IMG_START_TIME:  7613.94 SOD {02:06:53.94} UT,   1214.8 [sec] since BAT Trigger Time
FILTER:          0, illegal value
EXPOSURE_ID:     65537
X_OFFSET:        911 [pixels]
Y_OFFSET:        1281 [pixels]
WIDTH:           2016 [pixels]
HEIGHT:          305 [pixels]
X_GRB_POS:       0
Y_GRB_POS:       0
BINNING_INDEX:   0
IM_URL:          sw01253910000msuni0915.fits
SUN_POSTN:       170.64d {+11h 22m 33s}   +4.03d {+04d 01' 57"}
SUN_DIST:        169.47 [deg]   Sun_angle= 11.4 [hr] (West of Sun)
MOON_POSTN:      269.61d {+17h 58m 27s}  -28.71d {-28d 42' 48"}
MOON_DIST:        90.68 [deg]
MOON_ILLUM:      59 [%]
GAL_COORDS:       96.34,-60.19 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:        0.00,  0.00 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        WARNING: This Notice was received with 1 (or more) critical values out of range.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 1x1 binning (ie no compression).  
COMMENTS:        This notice was forced out after watchdog timer expiring -- most likely due to missing packet(s);  
COMMENTS:        as a consequence some of the fields may be incoorect (eg TRIGGER_NUM,RA,DEC).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 12 Sep 24 02:08:29 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1253910,   Seg_Num: 0
POINT_RA:          0.000d {+00h 00m 00s} (J2000)
POINT_DEC:        +0.000d {+00d 00' 00"} (J2000)
ROLL:            33.994d
IMG_START_DATE:  20565 TJD;   256 DOY;   24/09/12
IMG_START_TIME:  7613.94 SOD {02:06:53.94} UT,   1214.8 [sec] since BAT Trigger Time
FILTER:          0, illegal value
EXPOSURE_ID:     65537
X_OFFSET:        911 [pixels]
Y_OFFSET:        1281 [pixels]
WIDTH:           2016 [pixels]
HEIGHT:          305 [pixels]
X_GRB_POS:       0
Y_GRB_POS:       0
BINNING_INDEX:   0
IM_URL:          sw01253910000msuni0915.fits
SUN_POSTN:       170.64d {+11h 22m 33s}   +4.03d {+04d 01' 57"}
SUN_DIST:        169.47 [deg]   Sun_angle= 11.4 [hr] (West of Sun)
MOON_POSTN:      269.62d {+17h 58m 28s}  -28.71d {-28d 42' 48"}
MOON_DIST:        90.68 [deg]
MOON_ILLUM:      59 [%]
GAL_COORDS:       96.34,-60.19 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:        0.00,  0.00 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        WARNING: This Notice was received with 1 (or more) critical values out of range.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 1x1 binning (ie no compression).  
COMMENTS:        All 4 attachments are included.  
COMMENTS:        This notice was forced out after watchdog timer expiring -- most likely due to missing packet(s);  
COMMENTS:        as a consequence some of the fields may be incoorect (eg TRIGGER_NUM,RA,DEC).

GCN Circular #37466
P. A. Evans (U Leicester), R. Gupta (NASA GSFC), J. A. Kennea (PSU), K. L. Page (U Leicester) and D. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift Observatory Team:
At 01:46:39 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 240912A (trigger=1253910). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 124.633, +33.995 which is
```
   RA(J2000) = 08h 18m 32s
   Dec(J2000) = +33d 59' 42"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of at least 150 sec, extending into the observation times of the XRT and UVOT. The peak count rate was ~17000 counts/sec (15-350 keV), at ~69 sec after the trigger.
The XRT began observing the field at 01:48:25.2 UT, 106.0 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source located at RA, Dec 124.63711, 33.99865 which is equivalent to:
```
   RA(J2000)  = 08h 18m 32.91s
   Dec(J2000) = +33d 59' 55.1"
```
with an uncertainty of 3.5 arcseconds (radius, 90% containment). This location is 17 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 (5.53 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 4.2 (+2.90/-2.49) x 10^21 cm^-2 (90% confidence).
The initial flux in the 0.1 s image was 8.64e-08 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 115 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at
```
  RA(J2000)  =  08:18:32.40 = 124.63502
  DEC(J2000) = +33:59:56.3  =  33.99896
```
with a 90%-confidence error radius of about 0.75 arc sec. This position is 8.0 arc sec. from the center of the XRT error circle. The estimated magnitude is 17.40 with a 1-sigma error of about 0.14. No correction has been made for the expected extinction corresponding to E(B-V) of 0.054.
Burst Advocate for this burst is P. A. Evans (pae9 AT leicester.ac.uk). 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:     Thu 12 Sep 24 02:23:18 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     1253910,   Seg_Num: 0
GRB_RA:          124.6359d {+08h 18m 32.61s} (J2000),
                 125.0284d {+08h 20m 06.80s} (current),
                 123.8397d {+08h 15m 21.52s} (1950)
GRB_DEC:         +33.9986d {+33d 59' 54.9"} (J2000),
                 +33.9201d {+33d 55' 12.2"} (current),
                 +34.1552d {+34d 09' 18.8"} (1950)
GRB_ERROR:       3.5 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  20565 TJD;   256 DOY;   24/09/12
IMG_START_TIME:  7465.00 SOD {02:04:25.00} UT,   1065.8 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       170.65d {+11h 22m 36s}   +4.03d {+04d 01' 43"}
SUN_DIST:         51.82 [deg]   Sun_angle= 3.0 [hr] (West of Sun)
MOON_POSTN:      269.77d {+17h 59m 04s}  -28.71d {-28d 42' 53"}
MOON_DIST:       149.58 [deg]
MOON_ILLUM:      59 [%]
GAL_COORDS:      188.03, 31.92 [deg] galactic lon,lat of the burst
ECL_COORDS:      119.05, 13.99 [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:        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:     Thu 12 Sep 24 01:52:54 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1253910,   Seg_Num: 0
POINT_RA:        124.648d {+08h 18m 35s} (J2000)
POINT_DEC:       +33.994d {+33d 59' 39"} (J2000)
POINT_ROLL:      114.644d
IMG_START_DATE:  20565 TJD;   256 DOY;   24/09/12
IMG_START_TIME:  6514.41 SOD {01:48:34.41} UT,   115.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        5.868
N_STARS:         19
X_OFFSET:        416 [pixels]
Y_OFFSET:        616 [pixels]
X_MAX:           1375 [pixels]
Y_MAX:           1575 [pixels]
DET_THRESH:      21
PHOTO_THRESH:    12
SL_URL:          sw01253910000msufc0115.fits
SUN_POSTN:       170.63d {+11h 22m 31s}   +4.04d {+04d 02' 12"}
SUN_DIST:         51.79 [deg]   Sun_angle= 3.0 [hr] (West of Sun)
MOON_POSTN:      269.46d {+17h 57m 49s}  -28.71d {-28d 42' 41"}
MOON_DIST:       149.31 [deg]
MOON_ILLUM:      59 [%]
GAL_COORDS:      188.04, 31.93 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      119.06, 13.98 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 12 Sep 24 01:54:49 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1253910,   Seg_Num: 0
POINT_RA:        124.648d {+08h 18m 35s} (J2000)
POINT_DEC:       +33.994d {+33d 59' 39"} (J2000)
ROLL:            114.644d
IMG_START_DATE:  20565 TJD;   256 DOY;   24/09/12
IMG_START_TIME:  6514.41 SOD {01:48:34.41} UT,   115.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     747798548
X_OFFSET:        705 [pixels]
Y_OFFSET:        921 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       865
Y_GRB_POS:       1081
BINNING_INDEX:   1
IM_URL:          sw01253910000msuni0150.fits
SUN_POSTN:       170.63d {+11h 22m 31s}   +4.04d {+04d 02' 10"}
SUN_DIST:         51.79 [deg]   Sun_angle= 3.0 [hr] (West of Sun)
MOON_POSTN:      269.48d {+17h 57m 54s}  -28.71d {-28d 42' 42"}
MOON_DIST:       149.33 [deg]
MOON_ILLUM:      59 [%]
GAL_COORDS:      188.04, 31.93 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      119.06, 13.98 [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 NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 12 Sep 24 01:54:15 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1253910,   Seg_Num: 0
POINT_RA:        124.648d {+08h 18m 35s} (J2000)
POINT_DEC:       +33.994d {+33d 59' 39"} (J2000)
ROLL:            114.644d
IMG_START_DATE:  20565 TJD;   256 DOY;   24/09/12
IMG_START_TIME:  6514.41 SOD {01:48:34.41} UT,   115.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     747798548
X_OFFSET:        705 [pixels]
Y_OFFSET:        921 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       865
Y_GRB_POS:       1081
BINNING_INDEX:   1
IM_URL:          sw01253910000msuni0150.fits
SUN_POSTN:       170.63d {+11h 22m 31s}   +4.04d {+04d 02' 11"}
SUN_DIST:         51.79 [deg]   Sun_angle= 3.0 [hr] (West of Sun)
MOON_POSTN:      269.47d {+17h 57m 53s}  -28.71d {-28d 42' 42"}
MOON_DIST:       149.32 [deg]
MOON_ILLUM:      59 [%]
GAL_COORDS:      188.04, 31.93 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      119.06, 13.98 [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:     Thu 12 Sep 24 01:55:56 UT
NOTICE_TYPE:     Swift-UVOT Position
TRIGGER_NUM:     1253910,   Seg_Num: 0
GRB_RA:          124.6350d {+08h 18m 32.40s} (J2000),
                 125.0275d {+08h 20m 06.59s} (current),
                 123.8388d {+08h 15m 21.30s} (1950)
GRB_DEC:         +33.9989d {+33d 59' 56.0"} (J2000),
                 +33.9204d {+33d 55' 13.3"} (current),
                 +34.1555d {+34d 09' 19.9"} (1950)
GRB_ERROR:       0.8 [arcsec radius, statistical only]
GRB_MAG:         17.39 +/- 0.14 [mag]
FILTER:          10, White
IMG_START_DATE:  20565 TJD;   256 DOY;   24/09/12
IMG_START_TIME:  6511.00 SOD {01:48:31.00} UT,   111.8 [sec] since BAT Trigger Time
SUN_POSTN:       170.63d {+11h 22m 31s}   +4.04d {+04d 02' 09"}
SUN_DIST:         51.80 [deg]   Sun_angle= 3.0 [hr] (West of Sun)
MOON_POSTN:      269.49d {+17h 57m 57s}  -28.71d {-28d 42' 43"}
MOON_DIST:       149.35 [deg]
MOON_ILLUM:      59 [%]
GAL_COORDS:      188.03, 31.92 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      119.05, 13.99 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT UVOT Position Notice.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The UVOT position is 7.9 arcsec from the XRT position.  
COMMENTS:        Result based on Genie data.  
COMMENTS:        Notice generated automatically.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 12 Sep 24 01:53:13 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1253910,   Seg_Num: 0
POINT_RA:        124.648d {+08h 18m 35s} (J2000)
POINT_DEC:       +33.994d {+33d 59' 39"} (J2000)
POINT_ROLL:      114.644d
IMG_START_DATE:  20565 TJD;   256 DOY;   24/09/12
IMG_START_TIME:  6514.41 SOD {01:48:34.41} UT,   115.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        5.868
N_STARS:         19
X_OFFSET:        416 [pixels]
Y_OFFSET:        616 [pixels]
X_MAX:           1375 [pixels]
Y_MAX:           1575 [pixels]
DET_THRESH:      21
PHOTO_THRESH:    12
SL_URL:          sw01253910000msufc0115.fits
SUN_POSTN:       170.63d {+11h 22m 31s}   +4.04d {+04d 02' 12"}
SUN_DIST:         51.79 [deg]   Sun_angle= 3.0 [hr] (West of Sun)
MOON_POSTN:      269.46d {+17h 57m 50s}  -28.71d {-28d 42' 42"}
MOON_DIST:       149.32 [deg]
MOON_ILLUM:      59 [%]
GAL_COORDS:      188.04, 31.93 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      119.06, 13.98 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN Circular #37469
A. de Ugarte Postigo (LAM/OCA, CNRS), J. F. Agui Fernandez (CAHA), C. C. Thoene (ASU-CAS), N. A. Rakotondrainibe (LAM), N. R. Tanvir (U. Leicester), L. Izzo (INAF-OACn & DARK/NBI), S. Geier (GTC), G. Lombardi (GTC), J. P. U. Fynbo (DAWN/NBI), A. Martin-Carrillo (UCD), A. Garcia Rodriguez (GTC), A. Perez Romero (GTC) report,
We observed the afterglow of GRB 240912A (Fermi GBM team GCN 37465; Evans et al. GCN 37466) using OSIRIS+ on the 10.4 m GTC telescope, at the Roque de los Muchachos Observatory (La Palma, Spain). The observation consisted in 2 acquisition images in r-band, followed by a single 600 s spectra obtained just before the twilight became too bright to continue with observations. The spectrum was obtained with grism R1000B, covering the spectral range between 3650 and 7800 AA at a resolving power of 600.
The acquisition image, obtained at 2024-09-12T05:34:23 UT, 3.798 hrs after the burst, shows the afterglow at r(AB) = 19.15 +/- 0.08 mag, as compared to SDSS field stars. The spectrum has a strong continuum throughout the complete range with absorption features due to AlII, AlIII, FeII, MnII, MgII and MgI at a common redshift of 1.234, which we propose as the redshift of GRB 240912A.
GCN Circular #37470
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team.
Using 328 s of XRT Photon Counting mode data and 1 UVOT images for GRB 240912A, 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 = 124.63469, +33.99901 which is equivalent to:
```
RA (J2000): 08h 18m 32.32s
Dec (J2000): +33d 59' 56.4"
```
with an uncertainty of 2.5 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 #37471
J. An (NAOC), J.P.U. Fynbo (DAWN/NBI), S.Y. Fu, Z.P. Zhu, S.Q. Jiang, X. Liu, D. Xu (NAOC), Niilo Koivisto (NOT) report on behalf of a large collaboration:
We carried out the spectroscopy of the optical afterglow of GRB 240912A detected by Fermi/GBM (Fermi GBM team, GCN 37465) and Swift/BAT (Evans et al., GCN 37466), using the 2.56-m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera, at a mean time of 2024-09-12T05:20:43, i.e., ~ 3.57 hrs after the Swift/BAT trigger, covering the wavelength range between ~ 3600 AA and ~ 8000 AA.
A total of 970 s spectral exposure was obtained. A continuum is throughout the whole spectral wavelength range, superimposed with three relatively strong absorption features, which can be interpreted as due to Fe II, Mg II and Mg I at a common redshift of z = 1.23, in agreement with the GTC measurement (de Ugarte Postigo et al., GCN 37469).
GCN Circular #37473
Devraj Pawar (R. J. College, Mumbai-86, India) on behalf of a collaboration studying transients.
The Fermi GBM team reported detection of GRB 240912A in GCN 37465. We analyzed the INTEGRAL SPI ACS data around the given T0 and detected a multi-peak burst. The light curve is given on the following link and further outcomes will be updated on the same page. The SPI ACS is sensitive above 80 keV; the burst peaks at ~4200 counts/s above a steady rate of 3400 counts/s, this may be affected by the instruments orientation with respect to the direction of the source.
[https://docs.google.com/document/d/1e3pSUtLecDZTZkkMOuYGc6L4t64F4V-tjK1KT3_N7GE/edit?usp=sharing]()
This work is based on observations with INTEGRAL, an ESA project with instruments and a science data center funded by ESA member states (especially the PI countries: Denmark, France, Germany, Italy, Switzerland, Spain), and with the participation of Russia and the USA. The SPI-ACS detector system has been provided by MPE Garching/Germany.
GCN Circular #37476
I. P=C3=A9rez-Fournon and F. Poidevin (IAC and ULL)
Report on LCOGT follow-up observations of the optical afterglow of GRB 2409= 12A, detected by=20 the Fermi Gamma-ray Burst Monitor (GBM) (Fermi GBM team, GCN 37465); Swift = BAT, XRT, and UVOT (Evans et al., GCN 37466; an enhanced Swift XRT position= is given by Goad et al., GCN 37470); and with INTEGRAL ACS SPI (Pawar, GCN= 37473). Spectroscopy of the optical afterglow reported by de Ugarte Postig= o et al. (GCN 37469) and An et al. (GCN 37471) provides a redshift of z = 1.234, measured from absorption features.
We observed the field of GRB 240912A with one of the 1-meter telescopes at = the Las Cumbres Observatory node located at McDonald Observatory (Texas), w= ith a single 500-sec exposure in the SDSS-r' band starting at 2024-09-12T11= :13:18 (UTC), ~ 9.44 hours after the Fermi GBM trigger. We detect a point-like source at RA =3D 08:18:32.39, Dec =3D +33:59:56.1 (J= 2000) with an uncertainty of ~ 0.4", after astrometric calibration with Gai= a DR3 stars, at a magnitude r' =3D 19.88 +/- 0.05, calibrated with PanSTAR= RS and not corrected for Galactic extinction.
We report also the identification of the likely GRB host galaxy in archival= Legacy Surveys DR10 imaging at RA =3D 08:18:32.38, Dec =3D +33:59:55.3 (J2= 000) and magnitudes g =3D 23.08, r =3D 22.88; and z =3D 22.01.=20
The position of the optical afterglow on our LCOGT image is at about 0.2" from the Swift UVOT afterglow position and 0.8" from the DESI galaxy position.
This work makes use of observations from the Las Cumbres Observatory global telescope network (program IAC2024B-004).
GCN Circular #37477
V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik, D. Vlasenko, G.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij (Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA),
R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias),
D. Buckley (South African Astronomical Observatory),
O.A. Gress, N.M. Budnev, O.Ershova (Irkutsk State University, API),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
V. Yurkov, A. Gabovich (Blagoveschensk Educational State University)
MASTER-Tunka robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Applied Physics Institute, Irkutsk State University) was pointed to the Swift GRB 240912A ( P. A. Evans et al., GCN 37466) errorbox 58397 sec after notice time and 58417 sec after trigger time at 2024-09-12 18:00:16 UT, with upper limit up to 18.1 mag. The observations began at zenith distance = 80 deg. The sun altitude is -33.7 deg.
The galactic latitude b = 33 deg., longitude l = 188 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2598499
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

   58507 |        MASTER-Tunka |   C |   180 | 13.3 |        
   58898 |        MASTER-Tunka |   C |   180 | 18.1 |        
   59089 |        MASTER-Tunka |   C |   180 | 17.4 |        
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
GCN Circular #37478
J. Smith (UAH) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team:
"At 01:46:40.59 UT on 12 September 2024, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 240912A (trigger 747798405/240912074). which was also detected by Swift BAT and XRT (P. A. Evans et al. 2024, GCN 37466), INTEGRAL SPI ACS (D. Pawar 2024, GCN 37473), OSIRIS+/GTC (A. de Ugarte Postigo et al. 2024, GCN 37469), and NOT (J. An et al. 2024, GCN 37471). The Fermi GBM on-ground location is consistent with the Swift BAT/XRT position.
The angle from the Fermi LAT boresight is 71 degrees.
The GBM light curve single emission episode with a duration (T90) of about 88.6 s (50-300 keV). The time-averaged spectrum from T0+0 to T0+124.930 s is best fit by a Band function with Epeak = 147 +/- 7 keV, alpha = -1.31 +/- 0.02, and beta = -2.21 +/- 0.05.
The event fluence (10-1000 keV) in this time interval is (8.953 +/- 0.089)E-05 erg/cm^2. The 1.024-s peak photon flux measured starting from T0+60.2 s in the 10-1000 keV band is 26.43 +/- 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 #37479
D.N. Burrows (PSU), M. A. Williams (PSU), S. Dichiara (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A. Melandri (INAF-OAR), T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB) and P.A. Evans report on behalf of the Swift-XRT team:
We have analysed 6.9 ks of XRT data for GRB 240912A, from 99 s to 45.7 ks after the BAT trigger. The data comprise 939 s in Windowed Timing (WT) mode (the first 5 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=0.82 (+/-0.07).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.925 (+/-0.020). The best-fitting absorption column is 2.61 (+/-0.29) x 10^21 cm^-2, at a redshift of 1.234, in addition to the Galactic value of 5.6 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.86 (+/-0.09) and a best-fitting absorption column of 9 (+11, -9) x 10^20 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.6 x 10^-11 (4.1 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Galactic foreground: 5.6 x 10^20 cm^-2
Intrinsic column:    9 (+11, -9) x 10^20 cm^-2 at z=1.234
Photon index:	     1.86 (+/-0.09)
```
If the light curve continues to decay with a power-law decay index of 0.82, the count rate at T+24 hours will be 0.12 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.3 x 10^-12 (4.9 x 10^-12) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01253910.
This circular is an official product of the Swift-XRT team.
GCN Circular #37480
Geoffrey Mo (MIT), Tomas Ahumada (Caltech), Benjamin Schneider (MIT), Viraj= Karambelkar (Caltech), Danielle Frostig (CfA), Robert Stein (Caltech), Nat= han Lourie (MIT), Robert Simcoe (MIT), and Mansi Kasliwal (Caltech) report:
We observed the field of GRB 240912A (Fermi GBM Team, GCN 37465; Evans et al., GCN 37466; Pawar et al., GCN 37473; Smith et al., GCN 37478) in the near-infrared J-band with the Palomar 1-m telescope, equipped with the 1 square degree WINTER camera (Lourie et al. 2020).=20
Observations began at 2024-09-12T10:58:40 UTC (~9.2 hours after the GRB) an= d consisted of 15 x 120 s exposures. The images were processed using the WI= NTER data reduction pipeline (https://github.com/winter-telescope/mirar, ht= tps://doi.org/10.5281/zenodo.13352565).=20
We do not detect a source at the optical and refined Swift/XRT counterpart location (Evans et al., GCN 37466; de Ugarte Postigo et al., GCN 37469; Goa= d et al., GCN 37470; An et al., GCN 37471; P=C3=A9rez-Fournon et al., GCN 3= 7476; Lipunov et al., GCN 37477; Burrows et al., GCN 37479). We obtain the following 5-sigma upper limit: J ~ 18.7 mag (AB).
WINTER (Wide-field INfrared Transient ExploreR) is a partnership between MI= T and Caltech, housed at Palomar Observatory, and funded by NSF MRI, NSF AA= G, the David and Lucille Packard Foundation, and the MIT Kavli Institute fo= r Astrophysics and Space Research.
GCN Circular #37484
SVOM/GRM team: Chao Zheng, Wen-Jun Tan, Chen-Wei Wang, Wen-Long Zhang, Yong= -Wei Dong, Jiang-Tao Liu, Shi-Jie Zheng, Jian-Chao Sun, Yue Huang, Jiang He= , Min Gao, Hao-Xuan Guo, Lu Li, Yong-Ye Li, Hong-Wei Liu, Xin Liu, Hao-Li S= hi, Li-Ming Song, You-Li Tuo, Hao-Xi Wang, Jin Wang, Jin-Zhou Wang, Ping Wa= ng, Rui-Jie Wang, Yu-Xi Wang, Bo-Bing Wu, Shao-Lin Xiong, Jian-Ying Ye, Yi-= Tao Yin, Wen-Hui Yu, Fan Zhang, Li Zhang, Peng Zhang, Shuang-Nan Zhang, Ya= n-Ting Zhang, Yan-Qiu Zhang, Shu-Min Zhao, Xiao-Yun Zhao (IHEP), Maria-Graz= ia Bernardini (LUPM/INAF-OAB), Laurent Bouchet (IRAP), David Corre (CEA), T= ais Maiolino (LUPM), Fr=C3=A9d=C3=A9ric Piron (LUPM), St=C3=A9phane Schanne= (CEA), Jingwei Wang (IAP)
SVOM JSWG: Jian-Yan Wei (NAOC), Bertrand Cordier (CEA), Shuang-Nan Zhang (I= HEP), St=C3=A9phane Basa (LAM), JeanLuc Att=C3=A9ia (IRAP), Arnaud Claret (= CEA), Zi-Gao Dai (USTC), Fr=C3=A9d=C3=A9ric Daigne (IAP), Jin-Song Deng (NA= OC), Andrea Goldwurm (APC), Diego G=C3=B6tz (CEA), Xu-Hui Han (NAOC), Cyril= Lachaud (APC), En-Wei Liang (GXU), Yu-Lei Qiu (NAOC), Susanna Vergani (Obs= .Paris), Jing Wang (NAOC), Chao Wu (NAOC), Li-Ping Xin (NAOC), Bing Zhang (= UNLV)
report on behalf of the SVOM team:
During the commissioning phase, the SVOM/GRM was triggered in-flight by a l= ong GRB 240912A (SVOM trigger reference: sb24091203) at 2024-09-12T01:47:37= .000 UT (T0), which also triggered Fermi/GBM (Fermi GBM team, GCN 37465), S= wift/BAT (Evans et al., GCN 37466) and INTEGRAL SPI ACS (Pawar, GCN 37473).
With the event-by-event data downloaded through the X-band ground station, = the GRM light curve shows that this burst consists of multiple pulses with = a duration of about 79 s.
The GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb240912A.png
The Space Variable Objects Monitor (SVOM) is a China-France joint mission l= ed by the Chinese National Space Administration (CNSA, China), National Cen= ter for Space Studies (CNES, France) and the Chinese Academy of Sciences (C= AS, China), which is dedicated to observing gamma-ray bursts and other tran= sient phenomena in the energetic universe. GRM is developed by the Institut= e of High Energy Physics (IHEP) of CAS.
The SVOM point of contact for this burst is: Chao Zheng (IHEP)(zhengchao97@= ihep.ac.cn)

GCN Circular #37487
M. H. Siegel (PSU) and P. A. Evans (U. Leicester) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 240912A 115 s after the BAT trigger (Evans et al., GCN Circ. 37466). A fading source consistent with the XRT position (Goad et al., GCN Circ. 37470) is detected in the initial UVOT exposures.
The preliminary UVOT position is:

   RA  (J2000) =  08:18:32.40 = 124.63499 (deg.)
   Dec (J2000) = +33:59:56.3  =  33.99897 (deg.)

with an estimated uncertainty of 0.43 arc sec. (radius, 90% confidence).
Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white (fc)         117          265          144      17.44+/-0.05
white              608         1031          186      17.87+/-0.06
white             1185         1379           38      18.06+/-0.16
v                  657         1430           97      17.78+/-0.28
b                  583         5154          205      19.08+/-0.25
u (fc)             328          577          245      16.68+/-0.05
u                  731         5018          274      18.14+/-0.13
uvw1               707         1479           77      17.76+/-0.25
uvm2              1086         1106           19            >17.18
uvw2               633         1406           97      18.47+/-0.30

The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.054 in the direction of the burst (Schlegel et al. 1998).

GCN Circular #37539
T. Parsotan (GSFC), S. D. Barthelmy (GSFC), P. A. Evans (U Leicester), 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), D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 240912A (trigger #1253910) (P. A. Evans, et al., GCN Circ. 37466). The BAT ground-calculated position is RA, Dec = 124.625, 33.999 deg which is
```
   RA(J2000)  =  08h 18m 29.9s 
   Dec(J2000) = +33d 59' 56.2" 
```
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 86%.
The light curve displays an interval of weak flat emission for ~45 seconds before a bright multi-pulsed emission period. There is a possible shallow rise of emission at ~T0+280 seconds coincident with the flare seen in the XRT afterglow. T90 (15-350 keV) is 113.24 +- 7.83 sec (estimated error including systematics).
The time-averaged spectrum from T-2.35 to T+373.02 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 1.43 +- 0.11, and Epeak of 140.5 +- 41.0 keV (chi squared 27.79 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 3.4 +- 0.0 x 10^-05 erg/cm2 and the 1-sec peak flux measured from T+76.05 sec in the 15-150 keV band is 15.8 +- 0.5 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.68 +- 0.03 (chi squared 43.74 for 57 d.o.f.). 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/1253910
GCN Circular #37624
D. Svinkin, D. Frederiks, M. Ulanov, A. Tsvetkova, A. Lysenko, A. Ridnaia, and T. Cline on behalf of the Konus-Wind team, report:
The long-duration GRB 240912A (Fermi-GBM detection: The Fermi GBM Team, GCN 37465; Smith and Meegan, GCN 37478; Swift-BAT detection: Evans et al., GCN 37466; Parsotan et al., GCN 37539; INTEGRAL-SPI-ACS detection: Pawar et al., GCN 37473; SVOM-GRM detection: Zheng et al., GCN 37484) triggered Konus-Wind at T0 = 6454.746 s UT (01:47:34.746).
The burst light curve shows a multipeaked structure which starts at ~T0-60 s and has a total duration of ~118 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/GRB240912_T06454/
As observed by Konus-Wind, the burst had a fluence of 9.57(-0.96,+0.88)x10^-5 erg/cm2, and a 64-ms peak flux, measured from T0+2.496 s, of 7.32(-1.90,+1.87)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst (measured from T0 to T0+60.928 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -1.36(-0.11,+0.12), the high energy photon index beta = -2.44(-0.54,+0.18), the peak energy Ep = 196(-27,+37) keV (chi2 = 90/96 dof).
The spectrum near the maximum count rate (measured from T0+0.256 s to T0+6.144 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -1.12(-0.15,+0.16), the high energy photon index beta = -2.59(-7.41,+0.35), the peak energy Ep = 358(-77,+124) keV (chi2 = 89/72 dof).
Assuming the redshift z=1.234 (de Ugarte Postigo et al., GCN 37469) and a standard cosmology with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315, and Omega_Lambda = 0.685 (Planck Collaboration, 2014), we estimate the following rest-frame parameters: the isotropic energy release E_iso is 4.0(-0.4,+0.4)x10^53 erg, the peak luminosity L_iso is 6.8(-1.8,+1.7)x10^52 erg/s, the rest-frame peak energy of the time-averaged spectrum Ep,i,z is 437(-60,+82) keV, and the spectrum near the maximum count rate Ep,p,z is 799(-172,+277) keV.
With the obtained estimates, GRB 240912A is inside 68% prediction bands for 'Amati' and 'Yonetoku' relations, for the sample of >300 long KW GRBs with known redshifts (Tsvetkova et al., 2017; Tsvetkova et al., 2021), see http://www.ioffe.ru/LEA/GRBs/GRB240912_T06454/GRB240912A_rest_frame.pdf
All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.
GCN Circular #37978
S. Giarratana (INAF-OAB), M. Giroletti (INAF-IRA), G. Ghirlanda (INAF-OAB), N. Di Lalla (Stanford Univ.), N. Omodei (Stanford Univ.), O. S. Salafia (INAF-OAB)
At 16:50:36 UT on 2024 Oct 8 (T_mid = 26.7 days post-burst) the Karl G. Jansky VLA observed the field of GRB 240912A (Fermi GBM team, GCN 37465; Evans et al., GCN 37466; Pawar et al., GCN 37473; SVOM team, GCN 37484; Konus-Wind team, GCN 37624) in three bands, with central frequencies of 6, 10 and 15 GHz.
The standard 3C286 was used as bandpass and flux density calibrator, while J0815+3635 was used as phase calibrator.
From a preliminary analysis, an unresolved radio source is clearly detected at a position:
```
RA: 08:18:32.389 +- 0.001
Dec: 33:59:56.13 +- 0.02
```
consistent with the optical (Evans et al., GCN 37466) and X-ray (Goad et al., GCN 37470) transient.
The preliminary analysis yields the following results:
```
+-----------+-----------------------+--------------+-----------+-----------+
| Frequency | Peak surf. brightness | r.m.s. noise | Beam size | Beam P.A. |
|   (GHz)   |      (uJy/beam)       |  (uJy/beam)  |  arcsec^2 |    deg     |
+-----------+-----------------------+--------------+-----------+-----------+
|     6     |         171           |      8       | 1.34x0.28 |    60      |
|    10     |         138           |      7       | 0.93x0.17 |    57      |
|    15     |         128           |      7       | 0.54x0.12 |    62      |
+-----------+-----------------------+--------------+-----------+-----------+
```
No source is detected with a >3sigma confidence at the aforementioned position in previous radio surveys (FIRST, VLASS, RACS), all of which have r.m.s. noise levels above 100 uJy/b.
We would like to thank the staff of the VLA for approving, executing, and processing the observations.
The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
These observations were carried out as part of project SF171028, approved in the framework of the Fermi - NRAO joint program agreement.

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Jochen Greiner, last update: 30-Oct-2024 [Disclaimer]