Gamma-ray Burst 231215A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 15 Dec 23 09:47:53 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1202522,   Seg_Num: 0
GRB_RA:            9.750d {+00h 39m 00s} (J2000),
                  10.093d {+00h 40m 22s} (current),
                   9.038d {+00h 36m 09s} (1950)
GRB_DEC:         +57.642d {+57d 38' 32"} (J2000),
                 +57.774d {+57d 46' 25"} (current),
                 +57.368d {+57d 22' 03"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       10731 [cnts]    Image_Peak=232 [image_cnts]
TRIGGER_DUR:     2.048 [sec] 
TRIGGER_INDEX:   271     E_range: 50-350 keV
BKG_INTEN:       38409 [cnts]
BKG_TIME:        35207.44 SOD {09:46:47.44} UT
BKG_DUR:         24 [sec]
GRB_DATE:        20293 TJD;   349 DOY;   23/12/15
GRB_TIME:        35245.27 SOD {09:47:25.27} UT
GRB_PHI:         -174.19 [deg]
GRB_THETA:        57.17 [deg]
SOLN_STATUS:     0x20000003
RATE_SIGNIF:     98.44 [sigma]
IMAGE_SIGNIF:    9.55 [sigma]
MERIT_PARAMS:     +1  +0  +0  +1  +3  +0  +0  +1 +47  +0 
SUN_POSTN:       262.54d {+17h 30m 09s}  -23.26d {-23d 15' 28"}
SUN_DIST:        118.80 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      297.95d {+19h 51m 49s}  -26.11d {-26d 06' 23"}
MOON_DIST:       103.03 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      121.26, -5.19 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       38.47, 47.64 [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 = 303.83,18.75 [deg].  
COMMENTS:           
COMMENTS:        NOTE: This BAT event is temporally(8.0<100sec) coincident with the FERMI_GBM event (trignum=724326442).

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Fri 15 Dec 23 09:47:56 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      59
TRIGGER_NUM:     724326442
GRB_RA:          243.950d {+16h 15m 48s} (J2000),
                 243.920d {+16h 15m 41s} (current),
                 244.016d {+16h 16m 04s} (1950)
GRB_DEC:         +70.450d {+70d 27' 00"} (J2000),
                 +70.391d {+70d 23' 29"} (current),
                 +70.572d {+70d 34' 20"} (1950)
GRB_ERROR:       3.62 [deg radius, statistical plus systematic]
GRB_INTEN:       2753 [cnts/sec]
DATA_SIGNIF:     107.90 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        20293 TJD;   349 DOY;   23/12/15
GRB_TIME:        35237.81 SOD {09:47:17.81} UT
GRB_PHI:         204.00 [deg]
GRB_THETA:       155.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      0.44
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      95%  GRB
2nd_MOST_LIKELY:   4%  Generic Transient
DETECTORS:       0,0,0, 0,0,0, 0,0,1, 0,0,1, 0,0,
SUN_POSTN:       262.54d {+17h 30m 09s}  -23.26d {-23d 15' 28"}
SUN_DIST:         94.58 [deg]   Sun_angle= 1.2 [hr] (West of Sun)
MOON_POSTN:      297.96d {+19h 51m 49s}  -26.11d {-26d 06' 22"}
MOON_DIST:       103.74 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      103.61, 38.08 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      146.03, 79.79 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231215408/quicklook/glg_lc_medres34_bn231215408.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 160.97,-2.42 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(8.0<100sec) coincident with the SWIFT_BAT event (trignum=1202522).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Fri 15 Dec 23 09:48:06 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      58
TRIGGER_NUM:     724326442
GRB_RA:           11.220d {+00h 44m 53s} (J2000),
                  11.575d {+00h 46m 18s} (current),
                  10.485d {+00h 41m 56s} (1950)
GRB_DEC:         +61.240d {+61d 14' 24"} (J2000),
                 +61.371d {+61d 22' 15"} (current),
                 +60.967d {+60d 57' 60"} (1950)
GRB_ERROR:       1.92 [deg radius, statistical only]
DATA_SIGNIF:     90.40 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        20293 TJD;   349 DOY;   23/12/15
GRB_TIME:        35237.81 SOD {09:47:17.81} UT
GRB_PHI:         225.00 [deg]
GRB_THETA:       114.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4173 (Gnd S/W Version number)
SUN_POSTN:       262.54d {+17h 30m 09s}  -23.26d {-23d 15' 28"}
SUN_DIST:        119.35 [deg]   Sun_angle= -7.3 [hr] (East of Sun)
MOON_POSTN:      297.96d {+19h 51m 50s}  -26.11d {-26d 06' 21"}
MOON_DIST:       105.36 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      122.14, -1.62 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       42.64, 50.09 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231215408/quicklook/glg_lc_medres34_bn231215408.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_724326442.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        Bright hard burst in the GBM.  
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(8.0<100sec) coincident with the SWIFT_BAT event (trignum=1202522).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Fri 15 Dec 23 09:47:47 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      46
TRIGGER_NUM:     724326442
GRB_RA:          243.300d {+16h 13m 12s} (J2000),
                 243.268d {+16h 13m 04s} (current),
                 243.370d {+16h 13m 29s} (1950)
GRB_DEC:         +70.650d {+70d 39' 00"} (J2000),
                 +70.590d {+70d 35' 24"} (current),
                 +70.775d {+70d 46' 30"} (1950)
GRB_ERROR:       4.13 [deg radius, statistical plus systematic]
GRB_INTEN:       1182 [cnts/sec]
DATA_SIGNIF:     23.10 [sigma]
INTEG_TIME:      1.024 [sec]
GRB_DATE:        20293 TJD;   349 DOY;   23/12/15
GRB_TIME:        35237.81 SOD {09:47:17.81} UT
GRB_PHI:         204.00 [deg]
GRB_THETA:       155.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO:      0.36
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      96%  GRB
2nd_MOST_LIKELY:   3%  Generic Transient
DETECTORS:       0,0,0, 0,0,0, 0,0,1, 0,0,1, 0,0,
SUN_POSTN:       262.54d {+17h 30m 09s}  -23.26d {-23d 15' 28"}
SUN_DIST:         94.83 [deg]   Sun_angle= 1.3 [hr] (West of Sun)
MOON_POSTN:      297.95d {+19h 51m 49s}  -26.11d {-26d 06' 23"}
MOON_DIST:       104.04 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      103.97, 38.17 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      145.13, 79.55 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231215408/quicklook/glg_lc_medres34_bn231215408.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 160.97,-2.42 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(2.0<100sec) coincident with the CALET_GBM event (trignum=1386668712).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Fri 15 Dec 23 09:56:34 UT
NOTICE_TYPE:     Fermi-GBM Final Position
RECORD_NUM:      0
TRIGGER_NUM:     724326442
GRB_RA:           11.060d {+00h 44m 14s} (J2000),
                  11.414d {+00h 45m 39s} (current),
                  10.326d {+00h 41m 18s} (1950)
GRB_DEC:         +61.230d {+61d 13' 48"} (J2000),
                 +61.361d {+61d 21' 39"} (current),
                 +60.956d {+60d 57' 23"} (1950)
GRB_ERROR:       1.00 [deg radius, statistical only]
GRB_DATE:        20293 TJD;   349 DOY;   23/12/15
GRB_TIME:        35237.81 SOD {09:47:17.81} UT
GRB_PHI:         225.00 [deg]
GRB_THETA:       114.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       262.54d {+17h 30m 11s}  -23.26d {-23d 15' 29"}
SUN_DIST:        119.27 [deg]   Sun_angle= -7.3 [hr] (East of Sun)
MOON_POSTN:      298.05d {+19h 52m 12s}  -26.09d {-26d 05' 24"}
MOON_DIST:       105.23 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      122.07, -1.63 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       42.54, 50.13 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231215408/quicklook/glg_lc_medres34_bn231215408.gif
LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231215408/quicklook/glg_locplot_all_bn231215408.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:        Bright hard burst in the GBM.  
COMMENTS:        This is likely a Long GRB.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(8.0<100sec) coincident with the SWIFT_BAT event (trignum=1202522).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 15 Dec 23 09:51:27 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1202522,   Seg_Num: 0
GRB_RA:            9.750d {+00h 39m 00s} (J2000),
                  10.093d {+00h 40m 22s} (current),
                   9.038d {+00h 36m 09s} (1950)
GRB_DEC:         +57.642d {+57d 38' 32"} (J2000),
                 +57.774d {+57d 46' 25"} (current),
                 +57.368d {+57d 22' 03"} (1950)
GRB_DATE:        20293 TJD;   349 DOY;   23/12/15
GRB_TIME:        35245.27 SOD {09:47:25.27} UT
TRIGGER_INDEX:   271
GRB_PHI:         -174.19 [deg]
GRB_THETA:        57.17 [deg]
DELTA_TIME:      58.00 [sec]
TRIGGER_DUR:     2.048 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     98.44 [sigma]
IMAGE_SIGNIF:    9.55 [sigma]
LC_URL:          sw01202522000msb.lc
SUN_POSTN:       262.54d {+17h 30m 10s}  -23.26d {-23d 15' 29"}
SUN_DIST:        118.80 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      297.99d {+19h 51m 58s}  -26.10d {-26d 05' 59"}
MOON_DIST:       103.00 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      121.26, -5.19 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       38.47, 47.64 [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 = 303.83,18.75 [deg].

GCN Circular #35343
P. D'Avanzo (INAF-OAB), R. Brivio (INAF-OAB), M. Ferro (INAF-OAB), J.D. Gropp (PSU), K. L. Page (U Leicester), D. M. Palmer (LANL), T. Sakamoto (AGU), C. Salvaggio (INAF-OAB), T. Sbarrato (INAF-OAB), B. Sbarufatti (INAF-OAB) and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team:
At 09:47:25 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 231215A (trigger=1202522). Swift could not immediately slew due to an Earth limb observing constraint. The BAT on-board calculated location is RA, Dec 9.750, +57.642 which is
```
   RA(J2000) = 00h 39m 00s
   Dec(J2000) = +57d 38' 32"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 30 sec. The peak count rate was ~6000 counts/sec (15-350 keV), at ~1 sec after the trigger.
Due to an observing constraint, Swift will not slew until T0+42.6 minutes. There will be no XRT or UVOT data until this time.
Burst Advocate for this burst is P. D'Avanzo (paolo.davanzo AT inaf.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:     Fri 15 Dec 23 10:33:30 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     1202522,   Seg_Num: 0
GRB_RA:            9.7388d {+00h 38m 57.3s} (J2000),
                  10.0820d {+00h 40m 19.6s} (current),
                   9.0270d {+00h 36m 06.4s} (1950)
GRB_DEC:         +57.6456d {+57d 38' 44.1"} (J2000),
                 +57.7770d {+57d 46' 37.0"} (current),
                 +57.3709d {+57d 22' 15.3"} (1950)
GRB_ERROR:       5.4 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       24 [cnts]
IMG_START_DATE:  20293 TJD;   349 DOY;   23/12/15
IMG_START_TIME:  37971.00 SOD {10:32:51.00} UT,   2725.7 [sec] since BAT Trigger Time
CENTROID_X:      375.43,  raw= 375  [pixels]
CENTROID_Y:      283.91,  raw= 284  [pixels]
ROLL:            271.15 [deg]
GAIN:            2
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -33.44
GRB_POS_XRT_Z:   160.37
IMAGE_URL:       sw01202522000msxps_rw.img
SUN_POSTN:       262.57d {+17h 30m 17s}  -23.26d {-23d 15' 34"}
SUN_DIST:        118.78 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      298.45d {+19h 53m 48s}  -26.02d {-26d 01' 13"}
MOON_DIST:       102.72 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      121.26, -5.19 [deg] galactic lon,lat of the burst
ECL_COORDS:       38.47, 47.65 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.  
COMMENTS:        The object found at this position is either a very bright burst or a cosmic ray hit.  
COMMENTS:        Examine the XRT Image to differentiate (CRs are much more compact); see examples at:  
COMMENTS:        http://www.swift.psu.edu/xrt/XRT_Postage_Stamp_Image_Photo_Gallery.htm .

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 15 Dec 23 10:33:34 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     1202522,   Seg_Num: 0
GRB_RA:            9.7388d {+00h 38m 57.3s} (J2000),
                  10.0820d {+00h 40m 19.6s} (current),
                   9.0270d {+00h 36m 06.4s} (1950)
GRB_DEC:         +57.6456d {+57d 38' 44.1"} (J2000),
                 +57.7770d {+57d 46' 37.0"} (current),
                 +57.3709d {+57d 22' 15.3"} (1950)
GRB_ERROR:       5.4 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       24 [cnts]
IMG_START_DATE:  20293 TJD;   349 DOY;   23/12/15
IMG_START_TIME:  37971.00 SOD {10:32:51.00} UT,   2725.7 [sec] since BAT Trigger Time
CENTROID_X:      375.43,  raw= 375  [pixels]
CENTROID_Y:      283.91,  raw= 284  [pixels]
ROLL:            271.15 [deg]
GAIN:            2
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -33.44
GRB_POS_XRT_Z:   160.37
IMAGE_URL:       sw01202522000msxps_rw.img
SUN_POSTN:       262.57d {+17h 30m 17s}  -23.26d {-23d 15' 34"}
SUN_DIST:        118.78 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      298.45d {+19h 53m 48s}  -26.02d {-26d 01' 12"}
MOON_DIST:       102.72 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      121.26, -5.19 [deg] galactic lon,lat of the burst
ECL_COORDS:       38.47, 47.65 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.  
COMMENTS:        The object found at this position is either a very bright burst or a cosmic ray hit.  
COMMENTS:        Examine the XRT Image to differentiate (CRs are much more compact); see examples at:  
COMMENTS:        http://www.swift.psu.edu/xrt/XRT_Postage_Stamp_Image_Photo_Gallery.htm .

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 15 Dec 23 10:33:21 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     1202522,   Seg_Num: 0
GRB_RA:            9.7388d {+00h 38m 57.31s} (J2000),
                  10.0820d {+00h 40m 19.68s} (current),
                   9.0270d {+00h 36m 06.48s} (1950)
GRB_DEC:         +57.6456d {+57d 38' 44.1"} (J2000),
                 +57.7770d {+57d 46' 37.0"} (current),
                 +57.3709d {+57d 22' 15.3"} (1950)
GRB_ERROR:       5.5 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.09e-09 [erg/cm2/sec]
GRB_SIGNIF:      4.89 [sigma]
IMG_START_DATE:  20293 TJD;   349 DOY;   23/12/15
IMG_START_TIME:  37971.00 SOD {10:32:51.00} UT,   2725.7 [sec] since BAT Trigger Time
TAM[0-3]:        327.66 237.13 261.67 243.69
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       262.57d {+17h 30m 17s}  -23.26d {-23d 15' 34"}
SUN_DIST:        118.78 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      298.45d {+19h 53m 48s}  -26.02d {-26d 01' 14"}
MOON_DIST:       102.72 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      121.26, -5.19 [deg] galactic lon,lat of the burst
ECL_COORDS:       38.47, 47.65 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 0.41 arcmin from the BAT position.  
COMMENTS:        The object found at this position is either a very bright burst or a cosmic ray hit.  
COMMENTS:        Examine the XRT Image to differentiate (CRs are much more compact); see examples at:  
COMMENTS:        http://www.swift.psu.edu/xrt/XRT_Postage_Stamp_Image_Photo_Gallery.htm .

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 15 Dec 23 10:36:27 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1202522,   Seg_Num: 0
POINT_RA:          9.655d {+00h 38m 37s} (J2000)
POINT_DEC:       +57.637d {+57d 38' 14"} (J2000)
POINT_ROLL:      271.154d
IMG_START_DATE:  20293 TJD;   349 DOY;   23/12/15
IMG_START_TIME:  37978.08 SOD {10:32:58.08} UT,   2732.8 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.197
N_STARS:         190
X_OFFSET:        176 [pixels]
Y_OFFSET:        782 [pixels]
X_MAX:           1135 [pixels]
Y_MAX:           1741 [pixels]
DET_THRESH:      17
PHOTO_THRESH:    10
SL_URL:          sw01202522000msufc2732.fits
SUN_POSTN:       262.57d {+17h 30m 18s}  -23.26d {-23d 15' 35"}
SUN_DIST:        118.74 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      298.48d {+19h 53m 56s}  -26.01d {-26d 00' 52"}
MOON_DIST:       102.65 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      121.21, -5.19 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       38.41, 47.67 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 15 Dec 23 10:36:42 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1202522,   Seg_Num: 0
POINT_RA:          9.655d {+00h 38m 37s} (J2000)
POINT_DEC:       +57.637d {+57d 38' 14"} (J2000)
POINT_ROLL:      271.154d
IMG_START_DATE:  20293 TJD;   349 DOY;   23/12/15
IMG_START_TIME:  37978.08 SOD {10:32:58.08} UT,   2732.8 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.197
N_STARS:         190
X_OFFSET:        176 [pixels]
Y_OFFSET:        782 [pixels]
X_MAX:           1135 [pixels]
Y_MAX:           1741 [pixels]
DET_THRESH:      17
PHOTO_THRESH:    10
SL_URL:          sw01202522000msufc2732.fits
SUN_POSTN:       262.57d {+17h 30m 18s}  -23.26d {-23d 15' 35"}
SUN_DIST:        118.74 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      298.48d {+19h 53m 56s}  -26.01d {-26d 00' 51"}
MOON_DIST:       102.65 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      121.21, -5.19 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       38.41, 47.67 [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:     Fri 15 Dec 23 10:38:20 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1202522,   Seg_Num: 0
POINT_RA:          9.655d {+00h 38m 37s} (J2000)
POINT_DEC:       +57.637d {+57d 38' 14"} (J2000)
ROLL:            271.154d
IMG_START_DATE:  20293 TJD;   349 DOY;   23/12/15
IMG_START_TIME:  37978.08 SOD {10:32:58.08} UT,   2732.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     724329210
X_OFFSET:        546 [pixels]
Y_OFFSET:        1102 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       706
Y_GRB_POS:       1262
BINNING_INDEX:   1
IM_URL:          sw01202522000msuni2765.fits
SUN_POSTN:       262.58d {+17h 30m 18s}  -23.26d {-23d 15' 35"}
SUN_DIST:        118.73 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      298.50d {+19h 54m 01s}  -26.01d {-26d 00' 39"}
MOON_DIST:       102.64 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      121.21, -5.19 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       38.41, 47.67 [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:     Fri 15 Dec 23 10:38:33 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1202522,   Seg_Num: 0
POINT_RA:          9.655d {+00h 38m 37s} (J2000)
POINT_DEC:       +57.637d {+57d 38' 14"} (J2000)
ROLL:            271.154d
IMG_START_DATE:  20293 TJD;   349 DOY;   23/12/15
IMG_START_TIME:  37978.08 SOD {10:32:58.08} UT,   2732.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     724329210
X_OFFSET:        546 [pixels]
Y_OFFSET:        1102 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       706
Y_GRB_POS:       1262
BINNING_INDEX:   1
IM_URL:          sw01202522000msuni2765.fits
SUN_POSTN:       262.58d {+17h 30m 18s}  -23.26d {-23d 15' 35"}
SUN_DIST:        118.73 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      298.50d {+19h 54m 01s}  -26.01d {-26d 00' 38"}
MOON_DIST:       102.64 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      121.21, -5.19 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       38.41, 47.67 [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:     Fri 15 Dec 23 10:39:50 UT
NOTICE_TYPE:     Swift-UVOT Position
TRIGGER_NUM:     1202522,   Seg_Num: 0
GRB_RA:            9.7399d {+00h 38m 57.57s} (J2000),
                  10.0831d {+00h 40m 19.95s} (current),
                   9.0281d {+00h 36m 06.74s} (1950)
GRB_DEC:         +57.6475d {+57d 38' 51.0"} (J2000),
                 +57.7789d {+57d 46' 43.9"} (current),
                 +57.3728d {+57d 22' 22.1"} (1950)
GRB_ERROR:       1.1 [arcsec radius, statistical only]
GRB_MAG:         18.82 +/- 0.40 [mag]
FILTER:          10, White
IMG_START_DATE:  20293 TJD;   349 DOY;   23/12/15
IMG_START_TIME:  37975.00 SOD {10:32:55.00} UT,   2729.7 [sec] since BAT Trigger Time
SUN_POSTN:       262.58d {+17h 30m 18s}  -23.26d {-23d 15' 35"}
SUN_DIST:        118.78 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      298.52d {+19h 54m 04s}  -26.01d {-26d 00' 29"}
MOON_DIST:       102.68 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      121.26, -5.18 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       38.47, 47.65 [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 6.8 arcsec from the XRT position.  
COMMENTS:        Result based on srclist data.  
COMMENTS:        Notice generated automatically.

GCN Circular #35345
P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), D.N. Burrows (PSU), J.A. Kennea (PSU), S. Campana (INAF-OAB) and G. Cusumano (INAF-IASF PA) report on behalf of the Swift-XRT team:
The XRT began observing the field of GRB 231215A at 10:32:51.0 UT, 2725.7 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source located at RA, Dec 9.74175, 57.64645 which is equivalent to:
```
   RA(J2000)  = 00h 38m 58.02s
   Dec(J2000) = +57d 38' 47.2"
```
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This location is 22 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 (4.25 x 10^21 cm^-2, Willingale et al. 2013), with an excess column of 4.7 (+2.34/-2.12) x 10^21 cm^-2 (90% confidence).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 15 Dec 23 11:15:46 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     1202522,   Seg_Num: 0
GRB_RA:            9.7417d {+00h 38m 58.00s} (J2000),
                  10.0850d {+00h 40m 20.38s} (current),
                   9.0299d {+00h 36m 07.17s} (1950)
GRB_DEC:         +57.6465d {+57d 38' 47.4"} (J2000),
                 +57.7779d {+57d 46' 40.3"} (current),
                 +57.3718d {+57d 22' 18.5"} (1950)
GRB_ERROR:       3.6 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  20293 TJD;   349 DOY;   23/12/15
IMG_START_TIME:  37982.00 SOD {10:33:02.00} UT,   2736.7 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       262.60d {+17h 30m 25s}  -23.26d {-23d 15' 40"}
SUN_DIST:        118.77 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      298.91d {+19h 55m 38s}  -25.94d {-25d 56' 20"}
MOON_DIST:       102.44 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      121.26, -5.18 [deg] galactic lon,lat of the burst
ECL_COORDS:       38.47, 47.65 [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 0.58% < P(seren) < 1.1%.

GCN Circular #35346
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 GRB231215.41 (trigger No 1202522,00h 39m 00.00s , +57d 38m 31.2s, R=0.05) errorbox 2511 sec after notice time and 2545 sec after trigger time at 2023-12-15 10:29:50 UT, with upper limit up to 19.6 mag. Observations started at twilight. The observations began at zenith distance = 16 deg. The sun altitude is -13.1 deg.
The galactic latitude b = -5 deg., longitude l = 122 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2333312
We obtain a following upper limits.

Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

    2590 |        MASTER-Tunka |   C |    90 | 19.2 |        
    2625 |        MASTER-Tunka |   C |   160 | 19.3 |  Coadd 
    2769 |        MASTER-Tunka |   C |    10 | 19.0 |        
    2779 |        MASTER-Tunka |   C |    30 | 19.4 |  Coadd 
    2874 |        MASTER-Tunka |   C |   220 | 19.5 |  Coadd 
    2783 |        MASTER-Tunka |   C |    10 | 19.1 |        
    2797 |        MASTER-Tunka |   C |    10 | 19.1 |        
    2816 |        MASTER-Tunka |   C |    20 | 19.4 |        
    2841 |        MASTER-Tunka |   C |    70 | 19.6 |  Coadd 
    2840 |        MASTER-Tunka |   C |    20 | 19.3 |        
    2869 |        MASTER-Tunka |   C |    30 | 19.4 |        
    2903 |        MASTER-Tunka |   C |    30 | 19.4 |        
    2942 |        MASTER-Tunka |   C |    40 | 18.7 |        
    2991 |        MASTER-Tunka |   C |    50 | 18.9 |        
    3051 |        MASTER-Tunka |   C |   170 | 19.5 |  Coadd 
    3050 |        MASTER-Tunka |   C |    60 | 19.6 |        
    3114 |        MASTER-Tunka |   C |    60 | 19.6 |        
    3178 |        MASTER-Tunka |   C |    60 | 19.6 |        
    3242 |        MASTER-Tunka |   C |    60 | 19.6 |        
    3306 |        MASTER-Tunka |   C |    60 | 19.5 |        
    3369 |        MASTER-Tunka |   C |    60 | 19.5 |        
    3433 |        MASTER-Tunka |   C |    60 | 19.6 |        
    3497 |        MASTER-Tunka |   C |    60 | 19.6 |        
    3561 |        MASTER-Tunka |   C |    60 | 19.6 |        
    3625 |        MASTER-Tunka |   C |    60 | 19.5 |        
    3688 |        MASTER-Tunka |   C |    60 | 19.5 |        
    3752 |        MASTER-Tunka |   C |    60 | 19.5 |        
    3816 |        MASTER-Tunka |   C |    60 | 19.5 |        
    3880 |        MASTER-Tunka |   C |    60 | 19.5 |        
    3944 |        MASTER-Tunka |   C |    60 | 19.6 |        
    4008 |        MASTER-Tunka |   C |    60 | 19.6 |        
    4071 |        MASTER-Tunka |   C |    60 | 19.6 |        
    4135 |        MASTER-Tunka |   C |    60 | 19.6 |        
    4200 |        MASTER-Tunka |   C |    60 | 19.6 |        
    4264 |        MASTER-Tunka |   C |    60 | 19.6 |        
    4328 |        MASTER-Tunka |   C |    60 | 19.1 |        
    4392 |        MASTER-Tunka |   C |    60 | 19.1 |        
    4455 |        MASTER-Tunka |   C |    60 | 19.1 |        
    4520 |        MASTER-Tunka |   C |    60 | 19.1 |        
    4583 |        MASTER-Tunka |   C |    60 | 19.1 |        
    4647 |        MASTER-Tunka |   C |    60 | 19.1 |        
    4711 |        MASTER-Tunka |   C |    60 | 19.1 |        
    4775 |        MASTER-Tunka |   C |    60 | 19.1 |        
    4839 |        MASTER-Tunka |   C |    60 | 19.1 |        
    4902 |        MASTER-Tunka |   C |    60 | 19.1 |        
    4966 |        MASTER-Tunka |   C |    60 | 19.1 |        
    5030 |        MASTER-Tunka |   C |    60 | 19.1 |        
    5094 |        MASTER-Tunka |   C |    60 | 19.1 |        
    5157 |        MASTER-Tunka |   C |    60 | 19.1 |        
    5221 |        MASTER-Tunka |   C |    60 | 19.1 |        
    5285 |        MASTER-Tunka |   C |    60 | 19.1 |        
    5349 |        MASTER-Tunka |   C |    60 | 19.1 |        
    5412 |        MASTER-Tunka |   C |    60 | 19.1 |        
    5476 |        MASTER-Tunka |   C |    60 | 19.1 |        
    5541 |        MASTER-Tunka |   C |    60 | 19.1 |        
    5605 |        MASTER-Tunka |   C |    60 | 19.1 |        
    5669 |        MASTER-Tunka |   C |    60 | 19.1 |        
    5732 |        MASTER-Tunka |   C |    60 | 19.1 |        
    5796 |        MASTER-Tunka |   C |    60 | 19.1 |        
    5860 |        MASTER-Tunka |   C |    60 | 19.1 |        
    5924 |        MASTER-Tunka |   C |    60 | 19.1 |        
    5987 |        MASTER-Tunka |   C |    60 | 19.1 |        
    6051 |        MASTER-Tunka |   C |    60 | 19.1 |        
    6115 |        MASTER-Tunka |   C |    60 | 19.1 |        
    6179 |        MASTER-Tunka |   C |    60 | 19.1 |        
    6243 |        MASTER-Tunka |   C |    60 | 19.1 |        
    6307 |        MASTER-Tunka |   C |    60 | 19.1 |

Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.

GCN Circular #35347
V.Lipunov, P.Balanutsa (Lomonosov MSU), O.Gress, N.Budnev (ISU), E.Gorbovskoy, D.Svinkin (Ioffe Institute, Konus-Wind), Ya.Kechin, K.Zhirkov, A.Kuznetsov, D.Vlasenko, P.Balanutsa, Yu.Tselik, N.Tiurina, I.Gorbunov, V.Vladimirov,D.Zimnukhov, V.Senik, A.Yudin,A.Chasovnikov, D.Cheryasov, A.Sosnovskij (Lomonosov MSU,SAI,PhysicsDepartment), O.A. Gres, N.M. Budnev (Irkutsk State University, API), C.Francile. F. Podesta, R.Podesta (Observatorio Astronomico Felix Aguilar OAFA), R. Rebolo, M. Serra(The Instituto de Astrofisica de Canarias), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity)
MASTER Global robotic net (http://observ.pereplet.ru Lipunov et al.,2010,Advances in Astronomy,2010,30L) started Swift GRB 231215C ( D'Avanzo et al GCN 35343, Evans et al. GCN35345) at 2023-12-15 10:33:29UT (Lipunov et al. GCN 35346)
There is MASTER OT J003857.44+573850 since first image with mOT=16.5 at one of first image, with classical GRB light curve Observations and reduction will be continued
GCN Circular #35349
N. Pankov (HSE, IKI), A. Pozanenko (IKI), E. Klunko (ISTP), S. Belkin (IKI) report on behalf of GRB IKI FuN:
We observed the field of Swift GRB 231215A (D'Avanzo et al., GCN 35343; Evans et al., GCN 35345) with AZT-33IK telescope of Mondy observatory in R-filter starting on 2023-12-15 (UT) 11:17:39. Preliminary photometry of the fist immaes reveals a new bright source within XRT error circle (Evans et al., GCN 35345)
```
Date       UT start  t-T0     Exp.   Filter   OT     Err.
                   (mid, days)  (s)
2023-12-15 11:17:39  0.063363  1x120 R        17.42  0.07
```
The photometry is based on nearby USNO-B1.0 R2 stars.
We also may suggest that GCN 35347 (Lipunov et al.) refer to the afterglow of GRB 231215A.
GCN Circular #35351
M. Sasada, N. Higuchi, I. Takahashi, M. Niwano, S. Sato, S. Hayatsu, H. Takei, H. Seki, Y. Yatsu and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration:
We observed the field of GRB 231215A (D'Avanzo et al., GCN 35343) with the optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope Akeno.=20
The observation with a series of 10 sec exposures started at 2023-12-15 09:50:27 UT (182 seconds after the Swift/BAT trigger). We stacked the first six images. An optical candidate of the afterglow can be found at the location of (RA, Dec) =3D (9.7393, 57.6472) near the Swift/XRT error position (Evans et al., GCN 35345). Here we report magnitudes by the aperture photometry at the position.
```
T0+[sec] | MID-UT | T-EXP[sec] | magnitudes of aperture photometry
----------------------------------------------------------------------------------------------------------------
238 | 2023-12-15 09:51:23 | 60 | g=E2=80=99=3D17.54+/-0.06, Rc=3D17.86+/-0.05, Ic=3D17.40+/-0.05
----------------------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the trigger
T-EXP: Total Exposure time
```
The magnitudes are consistent with Lipunov et al., GCN 35347 and Pankov et = al., GCN 35349. We are continuing to observe the candidate.
We used the PS1 catalog for flux calibration. The catalog magnitudes in PS1= g, r and i bands were converted to our g'-, Rc- and Ic-band magnitudes fol= lowing Tonry et al. (2012), Table 6. The magnitudes are expressed in the AB= system. The images were processed in real-time through the MITSuME GPU red= uction pipeline (Niwano et al. 2021, PASJ, Vol.73, Issue 1, Pages 4-24; htt= ps://github.com/MNiwano/Eclaire).
GCN Circular #35352
P. K. Navaneeth (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:
Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a bright long-duration GRB 231215A which was also detected by Swift-BAT (D'Avanzo et al., GCN Circ. 35343), and Fermi-GBM (Fermi GBM Team, GCN Circ. 35344).
The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed two peaks of emission with the strongest peak at 2023-12-15 09:47:26.50 UTC. The measured peak count rate associated with the burst is 775 (+59, -30) counts/s above the background in the combined data of three quadrants (out of four), with a total of 8196 (+334, -292) counts. The local mean background count rate was 267 (+3, -3) counts/s. Using cumulative rates, we measure a T90 of 15 (+1, -1) s. In the preliminary analysis, we find 1372 Compton events associated with this event.
The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed two peaks of emission with the strongest peak at 2023-12-15 09:47:25.92 UTC. The measured peak count rate associated with the burst is 2162 (+110, -46) counts/s above the background in the combined data of all quadrants, with a total of 22784 (+686, -737) counts. The local mean background count rate was 1465 (+6, -7) counts/s. We measure a T90 of 14 (+1, -2) s from the cumulative Veto light curve.
CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.
CZTI GRB detections are reported regularly on the payload site at: http://astrosat.iucaa.in/czti/?q=grb
GCN Circular #35353
J. An, X. Liu, S.Q. Jiang, S.Y. Fu, T.H. Lu, Z.P. Zhu, D. Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:
We observed the field of GRB 231215A detected by Swift (D'Avanzo et al., GCN 35343) using the HMT-0.5m telescope located at Nanshan, Xinjiang, China. Observations started at 11:51:08 UT on 2023-12-15, i.e., 2.06 hr after the BAT trigger. A series of 90, 120, 200 s frames without any filter have been obtained and observations are ongoing.
Preliminary analysis of the initial frames shows that the previously reported optical afterglow (e.g., Pankov et al., GCN 35349; Sasada et al., GCN 35351) has decayed to m(r) = 18.3 +/- 0.1 mag at 2.19 hr post-burst, calibrated with the nearby PanSTAR field in the Sloan r-filter and the magnitude is not corrected for Galactic extinction.
GCN Circular #35354
Y. Wagh, R. Kumar, V. Swain, A. Salgundi, V. Bhalerao (IIT Bombay), G. C. Anupama, S. Barway (IIA), K. Angail (IAO)
We observed the field of GRB 231215A detected by Swift (D'Avanzo et al., GCN Circ. 35343) with 0.7m GROWTH-India Telescope (GIT). We started the observation at 2023-12-15 13:48:10.312 UT, i.e., 4.01 hours after the Swift trigger. We obtained multiple images in the r' and g' filters. We clearly detected the afterglow near the uncertainty radius of Swift-XRT position reported by P.A. Evans et al., GCN Circ. 35345 and are consistent with the coordinate reported by M. Sasada at al., GCN Circ. 35351. The photometry results follow as:
```
------------------------------------------------------------------------

| JD (mid) | t-t0 (hours) | Filter | Exposure (s) | Magnitude (AB) |

------------------------------------------------------------------------

| 2460294.07510789 | 4.008 | r' | 380 | 19.65 +/- 0.08 | 
| 2460294.08452486 | 4.248 | g' | 380 | 20.44 +/- 0.11 | 

------------------------------------------------------------------------
```
The results are consistent to the values reported by V.Lipunov et al., GCN Circ. 35347; N. Pankov et al., GCN Circ. 35349; M. Sasada et al., GCN Circ. 35351; J. An et al., GCN Circ. 35353. The magnitudes are calibrated against PanSTARRS DR1 (Chambers et al., 2016) and are 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 #35357
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team.
Using 1725 s of XRT Photon Counting mode data and 4 UVOT images for GRB 231215A, 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 = 9.73958, +57.64793 which is equivalent to:
```
RA (J2000): 00h 38m 57.50s
Dec (J2000): +57d 38' 52.6"
```
with an uncertainty of 2.2 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 #35361
F. Verrecchia (SSDC, and INAF/OAR), C. Casentini (INAF/IAPS), C. Pittori (SSDC, and INAF/OAR), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), A. Argan, M. Cardillo, Y. Evangelista, L. Foffano, G. Piano (INAF/IAPS), L. Baroncelli, A. Bulgarelli, A. Ciabattoni, A. Di Piano, V. Fioretti (INAF/OAS-Bologna), G. Panebianco (Univ. Bologna - INAF/OAS Bologna), N. Parmiggiani (INAF/OAS-Bologna), F. Lucarelli (SSDC, and INAF/OAR), P.W. Cattaneo (INFN Pavia), F. Longo (Univ. Trieste, and INFN Trieste), M. Marisaldi (INAF/OAS-Bologna, and Bergen University), M. Pilia, A. Trois (INAF/OA-Cagliari), A. Ursi (ASI and INAF/IAPS), I. Donnarumma, E. Menegoni (ASI), A. Giuliani (INAF/IASF-Mi), F. Cutrona (Univ. Milano Bicocca) and P. Tempesta (TeleSpazio) report on behalf of the AGILE Team:
The AGILE satellite detected the GRB 231215A at T0 = 2023-12-15 09:47:17.8 s (UTC), reported by Swift (GCNs #35343, #35345, #35357), Mondy (GCN #35349), MITSuME (GCN #35351), Astrosat (GCN #35352), HMT (GCN #35353), GROWTH (GCN #35354).
The event lasted about 12 s and it released a total number of 10990 counts in the MCAL detector RM (above a background rate of 548 Hz) and 49280 counts in the AC-Top detector RM (above a background rate of 2741 Hz). The AGILE ratemeters light curves can be found at
http://www.agilescienceapp.it/notices/GRB231215A_AGILE_RM_ND.png .
The event also triggered a high time resolution MCAL data acquisition, from T0-22 s s to T0+10 s (UTC), and released 8436 counts in the detector, above a background rate of 510 Hz. The MCAL light curve can be found at
http://www.agilescienceapp.it/notices/GRB231215A_086695_629718437.810000.png .
At the T0, the event was 148 deg off-axis. Additional analysis of AGILE data is in progress. Automatic MCAL GRB alert Notices can be found at: https://gcn.gsfc.nasa.gov/agile_mcal.html
GCN Circular #35362
Mohammad Odeh (Al-Khatim Observatory, AKO, operated by the International Astronomical Center in Abu Dhabi, UAE), and Dalya Akl (American University of Sharjah, UAE), report:
We used our 0.36m f/7.7 robotic telescope to observe the field of GRB 231215A, which was detected by Swift (D'Avanzo et al., GCN 35343), and its optical counterpart was detected by (Pankov et al., GCN 35349; Sasada et al., GCN 35351; An et al., GCN 35353; Wagh et al., GCN 35354).
The observation was done on 15 December starting at 20:07:36 UT, which corresponds to 10.34 hours after the GRB trigger time, using an (Ic) filter. We obtained 17x180s images, and we didn't detect a credible source within the uncertainty radius of the Swift-XRT position (Goad et al., GCN. 35357).
The following 5-sigma upper limit is calculated using the ATLAS catalog as a reference: Ic = 18.8 The magnitude is not corrected for Galactic extinction.
GCN Circular #35363
Y.-D. Hu, E. Fernandez-Garcia, I. Perez-Garcia, M.D. Caballero-Garcia, R. Sanchez-Ramirez, S. Guziy, S.-Y. Wu and A. J. Castro-Tirado (IAA-CSIC, Granada), C. Perez del Pulgar, A. Castellon, I. Carrasco (Univ. de Malaga) and D. R. Xiong, Y. F. Fan, J. M. Bai, C. J. Wang, Y. X. Xin, X. H. Zhao (Yunnan Observatories of CAS) on behalf of a larger collaboration, report:
Following the detection of GRB 231215A by Swift (D'Avanzo et al. GCNC 35343) and AGILE (Verrecchia et al. GCNC 35361), the 0.6m BOOTES-4/MET robotic telescope at Lijiang Astronomical Observatory (China) automatically responded to this burst starting on Dec. 15 at 14:11 UT (~4.4 hrs after trigger). A series of images in clear filter were gathered and the optical afterglow was detected within the enhanced Swift/XRT position (Goad et al. GCNC 35357) for which we measure a magnitude of 19.91 +- 0.14 on the co-added 60 s x 15 image, which is consistent with the detections of MASTER (Lipunov et al. GCNC 35347), Mondy (Pankov et al. GCNC 34349), MITSuME (Sasada et al. GCNC 35351), Nanshan/HMT (An et al. GCNC 35353) and GROWTH-India (Wagh et al. GCNC 35354). Further imaging is ongoing.
We thank the staff at Lijiang observatory for their excellent support.
GCN Circular #35364
K.L. Page (U. Leicester), V. D'Elia (SSDC & INAF-OAR), B. Sbarufatti (INAF-OAB), C. Salvaggio (INAF-OAB), D.N. Burrows (PSU), J. D. Gropp (PSU), S. Dichiara (PSU), A.P. Beardmore (U. Leicester) and P.A. Evans report on behalf of the Swift-XRT team:
We have analysed 6.7 ks of XRT data for GRB 231215A, from 2.7 ks to 33.0 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode.
The light curve can be modelled with a power-law decay with a decay index of alpha=1.95 (+0.10, -0.09).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.89 (+0.20, -0.13). The best-fitting absorption column is 4.40 (+1.19, -0.15) x 10^21 cm^-2, consistent with the Galactic value of 4.2 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.2 x 10^-11 (6.3 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     4.40 (+1.19, -0.15) x 10^21 cm^-2
Galactic foreground: 4.2 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.89 (+0.20, -0.13)
```
If the light curve continues to decay with a power-law decay index of 1.95, the count rate at T+24 hours will be 1.9 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.1 x 10^-14 (1.2 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/01202522.
This circular is an official product of the Swift-XRT team.
GCN Circular #35366
N. P. M. Kuin (UCL-MSSL) and P. D'Avanzo (INAF-OAB) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 231215A 2733 s after the BAT trigger (D'Avanzo et al., GCN Circ. 35343). A source consistent with the XRT position (Goad et al., GCN Circ. 35357) is detected in the initial UVOT exposures. The burst was also detected by Fermi GBM (GCN Circ. 35344),Astrosat CZTI (Navaneeth et al., GCN Circ. 35352), and in the optical by Master (Lipunov et al., 35347), MONDY (Pankov et al. GCN Circ. 35349), MITSume Akeno (Sasada et al., GCN Circ. 35351), GROWTH-India (Wagh et al., GCN Circ 35354), BOOTES-4/MET (Hu et al., GCN Circ 35363), HMT-Nanshang (An et al. GCN Circ. 35353) and an upper limit from AKO (Odeh, GCN Circ. 36362).
The preliminary UVOT position is:
```
    RA  (J2000) =  00:38:57.52 =   9.73967 (deg.)
    Dec (J2000) = +57:38:50.5  =  57.64735 (deg.)
```
with an estimated uncertainty of 0.45 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             2733         2883          147         18.10 +/- 0.05
v                 3713         3912          197         17.48 +/- 0.08
b                 3096         3296          197         18.63 +/- 0.09
u                 2891         3091          197         18.17 +/- 0.10
w1                4124         4323          197         19.57 +/- 0.31
m2                3918         4117          197        >19.4
w2                3507         3707          197        >19.5
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.506 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #35367
D. Turpin (CEA Paris-Saclay), C. Adami (LAM), E. Le Floc'h, D. G=C3=B6tz, F= . Sch=C3=BCssler (CEA Paris-Saclay), B. Schneider (MIT), S. Basa (Pytheas/O= HP/LAM), A. Saccardi, S. D. Vergani (GEPI, Obs. de Paris), report on behalf= of a larger collaboration:
We observed the field of the long GRB 231215A (D'Avanzo et al., GCN 35343) = and its afterglow candidate (Evans et al. GCN 35345) using the T193cm teles= cope at Observatoire de Haute-Provence (France) equipped with the MISTRAL i= nstrument. A total of 5 images were taken in r-band (total exposure =3D 300= 0s) and 3 others in the g-band (total exposure =3D 2100s) starting at 17:13= :33.32 UT on 2023-12-15, ~7.43h after the trigger.
In the combined frames, we clearly detect the optical afterglow reported by= Lipunov et al. GCN 35347, Pankov et al. GCN 35349, Sasada et al. GCN 35351= , An et al. GCN 35353, Wagh et al. GCN 35354, Hu et al. GCN 35363. The prel= iminary magnitude derived are the following:
```
-----------------------------------------------
T-T0 (in days, midtime) | mag | filter
-----------------------------------------------
0.3302 | 21.32 =C2=B1 0.10 mag (AB) | r'
0.3795 | 21.76 =C2=B1 0.07 mag (AB) | g'
-----------------------------------------------
```
The photometric calibration was performed using nearby stars from the PanST= ARRS catalog and magnitudes are not corrected for Galactic extinction.
Our results are compatibe with the fading behavior observed in previous GCN= (Lipunov et al. GCN 35347, Pankov et al. GCN 35349, Sasada et al. GCN 3535= 1, An et al. GCN 35353, Wagh et al. GCN 35354, Ferro et al. GCN 35355, Hu e= t al. GCN 35363). We note that the afterglow flux decay is steep with a tem= poral index alpha ~ 1.9. We encourage further follow-up observation with la= rge telescopes to better characterize the flux and spectral evolution of th= is afterglow.
We acknowledge the excellent support from Observatoire de Haute-Provence, i= n particular Jean Balcaen for the MISTRAL observations and the SOPHIE obser= ver Cl=C3=A9ment Ranc.
GCN Circular #35368
N. Cannady (GSFC/UMBC), A. Yoshida, T. Sakamoto, S. Sugita (AGU), Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA), Y. Asaoka (ICRR), S. Torii, Y. Akaike, K. Kobayashi (Waseda U), T. Tamura, Y. Shimizu (Kanagawa U), M. L. Cherry (LSU), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena), and the CALET collaboration:
The long GRB 231215A (Swift detection of a burst: D'Avanzo et al., GCN Circ. 35343; AstroSat CZTI detection: Navaneeth et al., GCN Circ. 35352; AGILE detection: Verrecchia et al., GCN Circ. 35361) triggered the CALET Gamma-ray Burst Monitor (CGBM) at 09:47:15.26 UTC on 15 December 2023 (http://cgbm.calet.jp/cgbm_trigger/flight/1386668712/). The burst signal was seen by all CGBM detectors.
The burst light curve shows a multi-peaked structure that starts at T+1.5 sec, peaks at T+10.4 sec, and ends at T+20.4 sec. The T90 and T50 durations measured by the SGM data are 15.2 +/- 1.3 sec and 5.6 +/- 0.2 sec (40-1000 keV), respectively.
The ground-processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1386668712/index.html
The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at Waseda University.
GCN Circular #35369
E. Bissaldi (Politecnico and INFN Bari), P. Veres (UAH) and C. Meegan (UAH) report on behalf of the Fermi GBM Team:
"At 09:47:17.81 UT on 15 December 2023, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 231215A (trigger 724326442 / 231215408), which was also detected by the Swift/BAT (D'Avanzo et al. 2023, GCN 35343). The GBM on-ground location is consistent with the Swift position. We note that the burst was automatically named incorrectly (GRB 231215B, GCN 35344), likely because the GBM trigger differs from the BAT trigger by 8 s.
The angle from the Fermi LAT boresight at the GBM trigger time is 111 degrees.
The GBM light curve consists of a single bright pulse with a duration (T90) of about 16 s (50-300 keV). The time-averaged spectrum from T0-1.8 s to T0+32 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is 0.73 +/- 0.02 and the cutoff energy, parameterized as Epeak, is 761 +/- 22 keV.
The event fluence (10-1000 keV) in this time interval is (7.15 +/- 0.05)E-5 erg/cm^2. The 1-sec peak photon flux measured starting from T0+7.5 s in the 10-1000 keV band is 20.3 +/- 0.4 ph/s/cm^2.
A Band function fits the spectrum equally well with Epeak= 759 +/- 23 keV, alpha = -0.73 +/- 0.02 and beta = 4.7 +/- 1.4.
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 #35370
Claudio Lopresti (Gruppo Astronomia Digitale - GAD Observatory, La Spezia, = Italy) in collaboration with: M.G. Dainotti (National Astronomical Observatory of Japan), Y. Niino (Tokyo= University, Institute of Astronomy), K. Kalinowski (Aarhus University, Dep= artment of Physics and Astronomy), B. De Simone (Universita' degli Studi Di= Salerno), Unione Astrofili Italiani (UAI) report:
We imaged the field of GRB 231215A (trigger=3D1202522) with the telescope L= X200 12=E2=80=9D of GAD Observatory, La Spezia, Italy Member of: UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili, GRB section. GAD - Gruppo Astronomia Digitale.
The observations started 551 min after the GRB trigger, with a Shmidt-Casse= grain telescope D=3D304 mm with reducer F/D=3D4.75.
Weather conditions were medium. The observation with a series of 60 sec exposures started at 2023-12-15 18:= 58:47 UT=20
We co-added 230 exposures of 60 sec each.
```
Start T0+      End T0+       R lim
551 min        815 min      17,99
```
We did not found any optical counterpart in 00:38:58.02 +57:38:47.2 positio= n and in the error box of the XRT candidate. ref.: P. D'Avanzo et al. GCN 35343, P.A. Evans et al. GCN 35345
Magnitudes were estimated with the Gaia EDR3 cat. and are not corrected for galactic dust extinction.
Reference: https://www.parcodellestelle.com/
The message may be cited.=20
GCN Circular #35373
C. C. Thoene (ASU-CAS), A. de Ugarte Postigo (CNRS/OCA and LAM), J. F. Agui= Fernandez (CAHA), L. Izzo (INAF/Capodimonte), J. P. U. Fynbo (DAWN/NBI), N= . R. Tanvir (U. Leicester), M. Blazek (CAHA), S. Geier, A. Cabrera-Lavers, = Fabricio Perez Toledo and Miguel Rivero (all GTC) report: =20 We obtained spectroscopy of the afterglow of GRB 231215A (D=E2=80=99Avanzo = et al. GCN 35343, Evans et al. GCN 35345, Pankov et al. GCN 35349) with OSI= RIS+ at the 10.4m GTC at a mean epoch of 0.4958 days after the GRB. The obs= ervation consisted of 3x900s exposures with grism R1000B, covering the rang= e between 3700 and 7780 AA at a resolving power of about 600.
The spectrum shows a strong but reddened continuum with multiple absorption= features. The highest redshift features include Lyman alpha, SII 1250,53,5= 9, SiII1260, 1304, OI1302, CII 1334, SiIV1393, 1402, CIV 1548, 1550, AlII16= 70, FeII 1608, 1611 at a common redshift of z=2.305. We also identify fin= e structure lines of SiII* 1264 and 1309 at the same redshift, which we hen= ce assume as the redshift of the GRB. Additionally, we detect two interveni= ng systems, at z=2.076 showing CIV and SiIV absorption and at z=0.574 showing the MgII 2796, 2803 doublet.
We thank the GTC staff for excellent support. This GRB reached Earth on the name's day of the first author.=20
GCN Circular #35375
Z. Zhu, J. An, D. Xu (NAOC), D. B. Malesani (DAWN/NBI), L. Izzo (INAF/Capod= imonte), A. de Ugarte Postigo (CNRS/OCA and LAM), Z. Gray (NOT) report on b= ehalf a large collaboration:
We observed the optical afterglow of GRB 231215A detected by Swift/BAT (D= =E2=80=99Avanzo et al., GCN 35343, Evans et al., GCN 35345, Pankov et al., = GCN 35349), using the 2.56-m Nordic Optical Telescope (NOT) equipped with t= he ALFOSC camera. Observations started at 20:23:33 UT on 2023-12-15, i.e., = 10.6 hr after the BAT trigger. We obtained 2x120 s in the Sloan r-band and = then 2x1800 s spectroscopy.
The previously reported optical counterpart (e.g., Lipunov et al., GCN 3534= 7, Pankov et al., GCN 35349, Sasada et al., GCN 35351, An et al., GCN 35353= , Wagh et al., GCN 35354, Hu et al., GCN 35363, Turpin et al., GCN 35367) w= as clearly detected in our stacked image with m(r) =3D 21.21 +/- 0.03 at 10= .64 hr post-burst, calibrated with nearby Pan-STARRS stars.
However, the S/N of the spectrum is quite low. The spectrum shows a rather = flat and featureless continuum. No unambiguous absorption feature can be id= entified at the reported GTC redshift (Thoene et al., GCN 35373).
GCN Circular #35376
A. Reguitti (INAF-OAB / INAF-OAPd), P. D'Avanzo (INAF-OAB), L. Tomasella (INAF -OAPd), E. Cappellaro (INAF -OAPd), report on behalf of the CIBO and of the GRAWITA collaborations:
We carried out follow-up optical observations of GRB 231215A (D'Avanzo et al., GCN Circ. 35343; Navaneeth et al. GCN Circ. 35352; Verrecchia et al. GCN Circ. 35361; Cannady et al., GCN Circ. 35368; Bissaldi et al., GCN Circ. 35369) from the INAF - Padova Astronomical Observatory located in Asiago (Italy) with the 67/92 Schmidt telescope starting on 2023-12-15 at 16:45:00 UT (~ 7.0 hours after the burst) with the clear filter.
In our stacked image the optical afterglow (Lipunov et al., GCN Circ. 35347, Pankov et al., GCN Circ. 35349, Sasada et al., GCN Circ. 35351, An et al., GCN Circ. 35353, Wagh et al., GCN Circ. 35354, Hu et al., GCN Circ. 35363; Kuin et al., GCN Circ. 35366; Turpin et al., GCN Circ. 35367; Zhu et al., GCN Circ. 35375) is detected. From preliminary analysis we estimate a magnitude of 21.2 +/- 0.2 (AB; calibrated against r band of the PanSTARRS catalog).
GCN Circular #35377
D. Frederiks, A.Lysenko, A. Ridnaia, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report:
The long, bright GRB 231215A (Swift detection: D'Avanzo et al., GCN 35343; AstroSat CZTI detection: Navaneeth et al., GCN 35352; CALET Gamma-Ray Burst Monitor detection: Cannady et al., GCN 35368; AGILE detection: Verrecchia et al., GCN 35361; Fermi GBM detection: Lesage et al., GCN 35369) triggered Konus-Wind (KW) at T0=3D35239.795 s UT (09:47:19.795).
The burst light curve shows a single multi-peaked pulse, which starts at ~T0-1 s, peaks at ~T0+9.5 s, and has a total duration of ~25 s. The emission is seen up to ~10 MeV.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB231215_T35239/
As observed by Konus-Wind, the burst had a fluence of (1.02 =C2=B1 0.09)x10^-4 erg/cm^2 and a 64-ms peak energy flux, measured from T0 + 28.352 s, of (1.14 =C2=B1 0.12)x10^-5 erg/cm^2/s (both in the 20 keV - 10 MeV energy = range).
The time-integrated spectrum (measured from T0 to T0+24.320 s) is best fit in the 20 keV - 15 MeV range by a GRB (Band) function with the following model parameters: the low-energy photon index alpha =3D -0.67 (-0.07,+0.08), the high energy photon index beta =3D -2.49 (-0.43,+0.22), the peak energy Ep =3D 612 (-63,+74) keV, chi2 =3D 80/97 dof.
The spectrum near the peak count rate (measured from T0+6.400s to T0+9.984s= ) is best fit in the 20 keV - 15 MeV range by a GRB (Band) function with the following model parameters: the low-energy photon index alpha =3D -0.49 (-0.09,+0.09), the high energy photon index beta =3D -3.07 (-2.04,+0.44), the peak energy Ep =3D 582 (-54,+58) keV, chi2 =3D 69/80 dof.
Assuming the redshift z=3D2.305 (Thoene et al., GCN 35373) and a standard cosmology with H_0 =3D 67.3 km/s/Mpc, Omega_M =3D 0.315, and Omega_Lambda =3D 0.685 (Planck Collaboration, 2014), we estimate the burst isotropic energy release E_iso to (1.35 =C2=B1 0.12)x= 10^54 erg, the isotropic peak luminosity L_iso to (4.93 =C2=B1 0.49)x10^53 erg/s, the rest-frame peak energy of the time-integrated spectrum Ep,i,z to ~2023 = keV, and the rest-frame peak energy at the peak of the emission Ep,p,z to ~1924 = keV. With the obtained estimates, GRB 230818A is inside 68% prediction band for both 'Amati' and 'Yonetoku' relations derived for the sample of >300 long KW GRBs with known redshifts (Tsvetkova et al., 2017; Tsvetkova et al., 202= 1), see http://www.ioffe.ru/LEA/GRBs/GRB231215_T35239/GRB231215A_rest_frame.pdf
All the quoted errors are estimated at the 68% confidence level. All the presented results are preliminary.
GCN Circular #35380
M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory), N. Werner= (Masaryk U.), M. Ohno, H. Takahashi (Hiroshima U.), L. Meszaros, B. Csak (= Konkoly Observatory), N. Husarikova, F. Munz , M. Topinka, M. Kolar, L. Sza= kszonova, J.-P. Breuer, F. Hroch (Masaryk U.), T. Urbanec, M. Kasal, A. Po= valac (Brno U. of Technology), J. Hudec, J. Kapus, M. Frajt (Spacemanic s.r= .o), R. Laszlo, M. Koleda (Needronix s.r.o), M. Smelko, P. Hanak, P. Lipovs= ky (Technical U. of Kosice), G. Galgoczi (Wigner Research Center/Eotvos U.)= , Y. Uchida, H. Poon, H. Matake (Hiroshima U.), N. Uchida (ISAS/JAXA), T. B= ozoki (Eotvos U.), G. Dalya (Eotvos U.), T. Enoto (Kyoto U.), Zs. Frei (Eot= vos U.), G. Friss (Eotvos U.), Y. Fukazawa, K. Hirose (Hiroshima U.), S. Hi= sadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), K. Kapas (Eotvos U.), L. L. Ki= ss (Konkoly Observatory), T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.= ), H. Odaka (Univ of Tokyo), J. Takatsy (Eotvos U.), K. Torigoe (Hiroshima = U.), N. Kogiso, M. Yoneyama (Osaka Metropolitan U.), M. Moritaki (U. Tokyo)= , T. Kano (U. Michigan) -- the GRBAlpha collaboration.
The long-duration GRB 231215A (Swift/BAT detection: GCN 35343; Fermi/GBM de= tection: GCN 35344; AstroSat detection: GCN 35352; AGILE detection: GCN 353= 61; CALET/CGBM detection: GCN 35368; Konus/Wind detection: GCN 35377; INTEG= RAL/SPI-ACS peak detection at 2023-12-15 ~09:47:26 UT) was observed by the = GRBAlpha 1U CubeSat (Pal et al. 2023, A&A, 677, 40; arXiv:2302.10048).
The detection was confirmed at the peak time 2023-12-15 09:47:27 UTC. The T= 90 duration measured by GRBAlpha is 16 s and the overall significance durin= g T90 reaches 42 sigma.
The light curve obtained by GRBAlpha is available here: https://grbalpha.ko= nkoly.hu/static/share/GRB231215A_GCN.pdf
All GRBAlpha detections are listed at: https://monoceros.physics.muni.cz/he= a/GRBAlpha/=20 GRBAlpha, launched on 2021 March 22, is a demonstration mission for a futur= e CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GR= BAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM ar= ray, covering the energy range from ~50 keV to ~1000 keV. To increase the d= uty cycle and the downlink rate, the upgrade of the on-board data acquisiti= on software stack is in progress. The ground segment is also supported by t= he radio amateur community and it takes advantage of the SatNOGS network fo= r increased data downlink volume.=20
GCN Circular #35386
S. D. Barthelmy (GSFC), P. D'Avanzo (INAF-OAB), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), M. Moss (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC/UMBC), T. Sakamoto (AGU), M. Stamatikos (OSU) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 231215A (trigger #1202522) (D'Avanzo, et al., GCN Circ. 35343). The BAT ground-calculated position is RA, Dec = 9.730, 57.634 deg which is
```
   RA(J2000)  =  00h 38m 55.1s
   Dec(J2000) = +57d 38' 00.8"
```
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment). The partial coding was 6%. The mask-weighted light curve shows a structure of several overlapping pulses. The emission starts from T-10 s, peaks at T0 and ends at T+20 s. T90 (15-350 keV) is 20.75 +- 3.69 sec (estimated error including systematics). The time-averaged spectrum from T-7.04 to T+19.79 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.01 +- 0.09. The fluence in the 15-150 keV band is 1.0 +- 0.1 x 10^-5 erg/cm2. The 1-sec peak photon flux measured from T+0.18 sec in the 15-150 keV band is 9.6 +- 1.4 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/1202522/BA/
GCN Circular #35392
Nello Ruocco at Osservatorio Nastro Verde - Sorrento (Naples) - Italy in a large collaboration with: M.G. Dainotti (National Astronomical Observatory of Japan), Y. Niino (Tokyo University, Institute of Astronomy), K. Kalinowski (Aarhus University, Department of Physics and Astronomy), B. De Simone (Universita' degli Studi Di Salerno) report:
We image the field of GRB 231215A detected by Swift Burst Alert Telescope (BAT)(trigger 1202522) with telescope of Nastro Verde Observatory - Sorrento (Naples), Italy. Member of: AAVSO - American Association of Variable Star Observers. UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili. AstroCampania Associazione
The observations started at 16:28 UT of 2023/12/15, after 6,40 hours after the GRB trigger, at the end of twilight with principal telescope SC 0.35 f/10 with focal reduced + CCD Sbig ST10 XME I took 20 image of 60 sec each. All images are unfiltered, calibrated with masterdark and masterflat,stacked with Tycho Tracker software We have not detected any clearly visible sources, up to 20th magnitude with clear skies.
```
Start T0+                End T0+       Rlim
16:28:50 UT            17:08:29 UT      20
```
We did not found any optical counterpart in the error box of the XRTcandidate. P. D'Avanzo et al. GCN 35343
Magnitudes were estimated with the Gaia DR2 cat. and are not corrected for galactic dust extinction.
The message may be cited.
GCN Circular #35397
Lauren Rhodes, Rob Fender (Oxford), Dave Green, Dave Titterington (Cambridge) report:
We observed the field of the afterglow candidate GRB 231215A (GCN 35343) with the Arcminute Microkelvin Imager Large-Array (AMI-LA) at 15.5 GHz beginning at UT 19:57:45 on 17-Dec-2023 for a total of 4 hours. The flux standard 3c286 was used to calibrate the bandpass response and flux scale of the AMI-LA and J0102+5824 was used as an interleaved complex gain calibrator.
We detect an unresolved radio source at the position of the afterglow candidate as reported in GCN 35345 with a flux density of ~220uJy/beam.
Further observations are planned. We thank the staff at the Mullard Radio Astronomy Observatory for carrying out these observations and operating the AMI-LA.
GCN Circular #35413
Chenyu Wang, Zirui Yang and Longhao Li report on behalf of the GRID Collabo= ration:
GRID-04 reports the detection of the long-duration GRB 231215A, which was a= lso detected by Swift/BAT, AstroSat CZTI, AGILE, Fermi/GBM, Konus-Wind and = GRBAlpha(GCN Circular 35343, 35352, 35361, 35369, 35377 and 35380).
The event was triggered with GRID on 2023-12-15 at 09:47:18.5 UTC. The meas= ured burst duration (T90) in the 30-2000 keV range is approximately 17.0 = =C2=B1 1.5 seconds.
The time-averaged spectrum of GRID-04 realtime data from T+0 to T+18 sec is= best fit by a cutoff power-law model. The index of the time-averaged spec= trum is -0.576(-0.108,+0.114) with a fluence in the 10-1000 keV band is abo= ut 5.2488E-05 erg/cm2. All the quoted errors are at the 1-sigma confidence = level.
The GRID light curve of this event can be found at https://mirrors.tuna.tsi= nghua.edu.cn/GRID/data/GRID-GCN/GRB231215A/GRID_231215A_ltcv.pdf. The GRID = spectrum of this event can be found at https://mirrors.tuna.tsinghua.edu.cn= /GRID/data/GRID-GCN/GRB231215A/GRID_231215A_spec_pl.pdf.
GRID is a student-led project to monitor the transient gamma-ray sky with m= ultiple detectors onboard different nanosatellites in the era of multi-mess= enger astronomy. For more information about GRID, please refer to the follo= wing references: https://doi.org/10.1007/s10686-019-09636-w and https://doi= .org/10.1007/s10686-021-09819-4.
GCN Circular #35507
S. Giarratana (University of Bologna, INAF-IRA), M. Giroletti (INAF-IRA), G. Ghirlanda (INAF-OAB), N. Di Lalla (Stanford Univ.), N. Omodei (Stanford Univ.)
At 03:57:39 UT on 2023 December 20 (T_mid = 4.8 days post-burst) the Karl G. Jansky VLA started observing the field of GRB 231215A (D'Avanzo et al., GCN 35343) at a central frequency of 6 and 10 GHz.
The standard J0542+4951 was used as bandpass and flux density calibrator, while J0102+5824 was used as complex gain calibrator.
From a preliminary analysis, an unresolved radio source (Rhodes et al., GCN 35397) is clearly detected at both frequencies at a position:
```
RA: 00:38:57.53 +- 0.05
Dec: +57:38:50.7 +- 0.6
```
The surface brightness peak is 61 uJy/beam and 128 uJy/beam at 6 and 10 GHz, respectively. The r.m.s. noise level of the images is 7 uJy/beam at both 6 and 10 GHz.
The synthesized beams are 13.1 x 9.9 arcsec (PA: -66deg) at 6 GHz and 7.7 x 6.0 arcsec (PA: -59deg) at 10 GHz.
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 SF161095, approved in the framework of the Fermi - NRAO joint program agreement.
GCN Circular #35900
S. Giarratana (University of Bologna, INAF-IRA), M. Giroletti (INAF-IRA), G. Ghirlanda (INAF-OAB), N. Di Lalla (Stanford Univ.), N. Omodei (Stanford Univ.)
At 02:46:36 UT on 2023 December 28 (T_mid =3D 12.7 days post-burst)=C2=A0 and at=C2=A001:39:51 UT on 2024 January 17 (T_mid =3D 32.7 days=C2=A0 post-burst) the Karl G. Jansky VLA observed the field of GRB 231215A (D'Avanzo et al., GCN 35343) at a central frequency of 6 and 10 GHz.=C2=A0
The standard J0542+4951 was used as bandpass and flux density calibrator, while J0102+5824 was used as phase calibrator.
From a preliminary analysis, the radio source coincident with GRB=C2=A0231215A (Rhodes et al., GCN 35397; Giarratana et al., GCN 35507) is still detected. We derive the following surface brightness peak estimates.
```
================================================================
T_mid    Freq     Peak     r.m.s.   Beam         PA
[days]   [GHz]    [uJy/b]  [uJy/b] [arcsec]     [deg]
================================================================
12.7     6        110      8        11.69x9.50   -44
12.7     10       127      7        7.06x5.79    -33
32.7     6        48       7        7.34x4.23    -31
32.7     10       62       6        5.27x3.13    -24
================================================================
```
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 SF161095, approved in the framework of the Fermi - NRAO joint program agreement.

Back to JG's homepage

Jochen Greiner, last update: 08-Mar-2024 [Disclaimer]