Gamma-ray Burst 221226B

(All information courtesy of the instrument teams.)

Previous IAU Circulars

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Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 26 Dec 22 22:41:35 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1145959,   Seg_Num: 0
GRB_RA:           22.917d {+01h 31m 40s} (J2000),
                  23.167d {+01h 32m 40s} (current),
                  22.372d {+01h 29m 29s} (1950)
GRB_DEC:         -41.554d {-41d 33' 13"} (J2000),
                 -41.436d {-41d 26' 09"} (current),
                 -41.811d {-41d 48' 38"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       1103 [cnts]    Image_Peak=93 [image_cnts]
TRIGGER_DUR:     0.512 [sec] 
TRIGGER_INDEX:   121     E_range: 15-50 keV
BKG_INTEN:       9961 [cnts]
BKG_TIME:        81665.53 SOD {22:41:05.53} UT
BKG_DUR:         8 [sec]
GRB_DATE:        19939 TJD;   360 DOY;   22/12/26
GRB_TIME:        81680.06 SOD {22:41:20.06} UT
GRB_PHI:         -50.93 [deg]
GRB_THETA:        10.60 [deg]
SOLN_STATUS:     0x20000003
RATE_SIGNIF:     17.77 [sigma]
IMAGE_SIGNIF:    7.70 [sigma]
MERIT_PARAMS:     +1  +0  +0  -1  +1  -2  +0  +0  -5  +0 
SUN_POSTN:       275.60d {+18h 22m 24s}  -23.34d {-23d 20' 08"}
SUN_DIST:         86.88 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      328.42d {+21h 53m 40s}  -18.10d {-18d 06' 11"}
MOON_DIST:        51.91 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      275.74,-73.38 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:        0.29,-46.43 [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 = 345.01,8.36 [deg].  
COMMENTS:           
COMMENTS:        NOTE: This BAT event is temporally(0.0<100sec) coincident with the FERMI_GBM event (trignum=693787285).

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 26 Dec 22 22:41:50 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      46
TRIGGER_NUM:     693787285
GRB_RA:            4.867d {+00h 19m 28s} (J2000),
                   5.149d {+00h 20m 36s} (current),
                   4.251d {+00h 17m 00s} (1950)
GRB_DEC:         -48.217d {-48d 13' 00"} (J2000),
                 -48.089d {-48d 05' 20"} (current),
                 -48.494d {-48d 29' 38"} (1950)
GRB_ERROR:       12.87 [deg radius, statistical plus systematic]
GRB_INTEN:       188 [cnts/sec]
DATA_SIGNIF:     9.30 [sigma]
INTEG_TIME:      1.024 [sec]
GRB_DATE:        19939 TJD;   360 DOY;   22/12/26
GRB_TIME:        81680.42 SOD {22:41:20.42} UT
GRB_PHI:         238.00 [deg]
GRB_THETA:        45.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO:      0.97
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      96%  GRB
2nd_MOST_LIKELY:   1%  Generic Transient
DETECTORS:       0,0,0, 0,0,0, 1,1,0, 0,0,0, 0,0,
SUN_POSTN:       275.60d {+18h 22m 24s}  -23.34d {-23d 20' 08"}
SUN_DIST:         72.57 [deg]   Sun_angle= -6.0 [hr] (East of Sun)
MOON_POSTN:      328.42d {+21h 53m 40s}  -18.10d {-18d 06' 07"}
MOON_DIST:        42.26 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      317.26,-68.01 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      339.76,-44.96 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn221226945/quicklook/glg_lc_medres34_bn221226945.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 175.05,-17.98 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(0.0<100sec) coincident with the SWIFT_BAT event (trignum=1145959).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 26 Dec 22 22:42:07 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      58
TRIGGER_NUM:     693787285
GRB_RA:           19.600d {+01h 18m 24s} (J2000),
                  19.828d {+01h 19m 19s} (current),
                  19.103d {+01h 16m 25s} (1950)
GRB_DEC:         -57.180d {-57d 10' 47"} (J2000),
                 -57.060d {-57d 03' 33"} (current),
                 -57.443d {-57d 26' 33"} (1950)
GRB_ERROR:       6.73 [deg radius, statistical only]
DATA_SIGNIF:     15.60 [sigma]
DATA_INTERVAL:   2.048 [sec]
GRB_DATE:        19939 TJD;   360 DOY;   22/12/26
GRB_TIME:        81680.42 SOD {22:41:20.42} UT
GRB_PHI:         220.00 [deg]
GRB_THETA:        44.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4173 (Gnd S/W Version number)
SUN_POSTN:       275.60d {+18h 22m 24s}  -23.34d {-23d 20' 08"}
SUN_DIST:         77.89 [deg]   Sun_angle= -6.9 [hr] (East of Sun)
MOON_POSTN:      328.42d {+21h 53m 41s}  -18.10d {-18d 06' 04"}
MOON_DIST:        54.33 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      295.72,-59.57 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      341.84,-57.50 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn221226945/quicklook/glg_lc_medres34_bn221226945.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_693787285.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        In the LAT Field-of-view.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file will not be created/available until ~15 min after the trigger.  
COMMENTS:        The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(0.0<100sec) coincident with the SWIFT_BAT event (trignum=1145959).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 26 Dec 22 22:50:48 UT
NOTICE_TYPE:     Fermi-GBM Final Position
RECORD_NUM:      0
TRIGGER_NUM:     693787285
GRB_RA:           16.280d {+01h 05m 07s} (J2000),
                  16.527d {+01h 06m 06s} (current),
                  15.742d {+01h 02m 58s} (1950)
GRB_DEC:         -52.970d {-52d 58' 11"} (J2000),
                 -52.847d {-52d 50' 49"} (current),
                 -53.238d {-53d 14' 14"} (1950)
GRB_ERROR:       9.78 [deg radius, statistical only]
GRB_DATE:        19939 TJD;   360 DOY;   22/12/26
GRB_TIME:        81680.42 SOD {22:41:20.42} UT
GRB_PHI:         226.00 [deg]
GRB_THETA:        46.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       275.61d {+18h 22m 25s}  -23.34d {-23d 20' 07"}
SUN_DIST:         77.84 [deg]   Sun_angle= -6.7 [hr] (East of Sun)
MOON_POSTN:      328.51d {+21h 54m 02s}  -18.07d {-18d 04' 10"}
MOON_DIST:        50.86 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      298.22,-64.03 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      344.28,-53.09 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn221226945/quicklook/glg_lc_medres34_bn221226945.gif
LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn221226945/quicklook/glg_locplot_all_bn221226945.png
COMMENTS:        Fermi-GBM Final Position.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file should be available by the time this FINAL notice is produced.  
COMMENTS:        This notice was generated completely by automated pipeline processing.  
COMMENTS:        In the LAT Field-of-view.  
COMMENTS:        This is likely a Long GRB.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(0.0<100sec) coincident with the SWIFT_BAT event (trignum=1145959).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 26 Dec 22 22:42:38 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     1145959,   Seg_Num: 0
POINT_RA:         22.930d {+01h 31m 43s} (J2000)
POINT_DEC:       -41.551d {-41d 33' 03"} (J2000)
IMG_START_DATE:  19939 TJD;   360 DOY;   22/12/26
IMG_START_TIME:  81752.46 SOD {22:42:32.46} UT,   72.4 [sec] since BAT Trigger 
Time
COUNTS:          7    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        1    Max_iter_allowed= 4
ERROR_CODE:      1
COMMENTS:        SWIFT-XRT Nack Position.  
COMMENTS:        No source found in the image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 26 Dec 22 22:45:24 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1145959,   Seg_Num: 0
POINT_RA:         22.930d {+01h 31m 43s} (J2000)
POINT_DEC:       -41.551d {-41d 33' 02"} (J2000)
POINT_ROLL:      241.397d
IMG_START_DATE:  19939 TJD;   360 DOY;   22/12/26
IMG_START_TIME:  81755.86 SOD {22:42:35.86} UT,   75.8 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.675
N_STARS:         28
X_OFFSET:        549 [pixels]
Y_OFFSET:        535 [pixels]
X_MAX:           1508 [pixels]
Y_MAX:           1494 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw01145959000msufc0075.fits
SUN_POSTN:       275.60d {+18h 22m 24s}  -23.34d {-23d 20' 08"}
SUN_DIST:         86.89 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      328.45d {+21h 53m 49s}  -18.09d {-18d 05' 21"}
MOON_DIST:        51.90 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      275.71,-73.38 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:        0.30,-46.43 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 26 Dec 22 22:45:36 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1145959,   Seg_Num: 0
POINT_RA:         22.930d {+01h 31m 43s} (J2000)
POINT_DEC:       -41.551d {-41d 33' 02"} (J2000)
POINT_ROLL:      241.397d
IMG_START_DATE:  19939 TJD;   360 DOY;   22/12/26
IMG_START_TIME:  81755.86 SOD {22:42:35.86} UT,   75.8 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.675
N_STARS:         28
X_OFFSET:        549 [pixels]
Y_OFFSET:        535 [pixels]
X_MAX:           1508 [pixels]
Y_MAX:           1494 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw01145959000msufc0075.fits
SUN_POSTN:       275.60d {+18h 22m 24s}  -23.34d {-23d 20' 07"}
SUN_DIST:         86.89 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      328.46d {+21h 53m 49s}  -18.09d {-18d 05' 18"}
MOON_DIST:        51.90 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      275.71,-73.38 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:        0.30,-46.43 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 26 Dec 22 22:46:38 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1145959,   Seg_Num: 0
POINT_RA:         22.930d {+01h 31m 43s} (J2000)
POINT_DEC:       -41.551d {-41d 33' 02"} (J2000)
ROLL:            241.397d
IMG_START_DATE:  19939 TJD;   360 DOY;   22/12/26
IMG_START_TIME:  81755.86 SOD {22:42:35.86} UT,   75.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     693787386
X_OFFSET:        868 [pixels]
Y_OFFSET:        854 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1028
Y_GRB_POS:       1014
BINNING_INDEX:   1
IM_URL:          sw01145959000msuni0106.fits
SUN_POSTN:       275.60d {+18h 22m 25s}  -23.34d {-23d 20' 07"}
SUN_DIST:         86.89 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      328.47d {+21h 53m 52s}  -18.08d {-18d 05' 05"}
MOON_DIST:        51.89 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      275.71,-73.38 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:        0.30,-46.43 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 26 Dec 22 22:46:44 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1145959,   Seg_Num: 0
GRB_RA:           22.917d {+01h 31m 40s} (J2000),
                  23.167d {+01h 32m 40s} (current),
                  22.372d {+01h 29m 29s} (1950)
GRB_DEC:         -41.554d {-41d 33' 13"} (J2000),
                 -41.436d {-41d 26' 09"} (current),
                 -41.811d {-41d 48' 38"} (1950)
GRB_DATE:        19939 TJD;   360 DOY;   22/12/26
GRB_TIME:        81680.06 SOD {22:41:20.06} UT
TRIGGER_INDEX:   121
GRB_PHI:         -50.93 [deg]
GRB_THETA:        10.60 [deg]
DELTA_TIME:      -11.00 [sec]
TRIGGER_DUR:     0.512 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     17.77 [sigma]
IMAGE_SIGNIF:    7.70 [sigma]
LC_URL:          sw01145959000msb.lc
SUN_POSTN:       275.60d {+18h 22m 25s}  -23.34d {-23d 20' 07"}
SUN_DIST:         86.88 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      328.47d {+21h 53m 52s}  -18.08d {-18d 05' 03"}
MOON_DIST:        51.89 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      275.74,-73.38 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:        0.29,-46.43 [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 = 345.01,8.36 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 26 Dec 22 22:46:51 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1145959,   Seg_Num: 0
POINT_RA:         22.930d {+01h 31m 43s} (J2000)
POINT_DEC:       -41.551d {-41d 33' 02"} (J2000)
ROLL:            241.397d
IMG_START_DATE:  19939 TJD;   360 DOY;   22/12/26
IMG_START_TIME:  81755.86 SOD {22:42:35.86} UT,   75.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     693787386
X_OFFSET:        868 [pixels]
Y_OFFSET:        854 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1028
Y_GRB_POS:       1014
BINNING_INDEX:   1
IM_URL:          sw01145959000msuni0106.fits
SUN_POSTN:       275.60d {+18h 22m 25s}  -23.34d {-23d 20' 07"}
SUN_DIST:         86.89 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      328.47d {+21h 53m 52s}  -18.08d {-18d 05' 02"}
MOON_DIST:        51.89 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      275.71,-73.38 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:        0.30,-46.43 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 26 Dec 22 22:53:20 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1145959,   Seg_Num: 0
POINT_RA:         22.930d {+01h 31m 43s} (J2000)
POINT_DEC:       -41.551d {-41d 33' 03"} (J2000)
ROLL:            241.394d
IMG_START_DATE:  19939 TJD;   360 DOY;   22/12/26
IMG_START_TIME:  81967.78 SOD {22:46:07.78} UT,   287.7 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     693787598
X_OFFSET:        868 [pixels]
Y_OFFSET:        854 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1028
Y_GRB_POS:       1014
BINNING_INDEX:   1
IM_URL:          sw01145959000msuni0318.fits
SUN_POSTN:       275.61d {+18h 22m 26s}  -23.34d {-23d 20' 07"}
SUN_DIST:         86.89 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      328.53d {+21h 54m 08s}  -18.06d {-18d 03' 37"}
MOON_DIST:        51.86 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      275.70,-73.38 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:        0.31,-46.43 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN Circular #33106
V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D.Cheryasov, Ya.Kechin (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. Gres, N.M. Budnev (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),
A. Gabovich, V.Yurkov (Blagoveschensk Educational State University)
MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB221226.95 (trigger No 1145959,01h 31m 40.08s , -41d 33m 14.4s, R=0.05) errorbox 21 sec after notice time and 42 sec after trigger time at 2022-12-2 6 22:42:02 UT, with upper limit up to 15.9 mag. The observations began at zenith distance = 58 deg. The sun altitude is -34. 6 deg.
The galactic latitude b = -73 deg., longitude l = 274 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2187664
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

      47 |         MASTER-SAAO |  P/ |    10 | 15.9 |        
```
The observation and reduction will continue. The message may be cited.
GCN Circular #33107
The Fermi GBM team reports the detection of a likely LONG GRB
At 22:41:20 UT on 26 Dec 2022, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 221226B (trigger 693787285.418 586 / 221226945).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 16.3, Dec = -53.0 (J2000 degrees, equivalent to J2 000 01h 05m, -53d 00'), with a statistical uncertainty of 9.8 degrees.
The angle from the Fermi LAT boresight is 46.0 degrees.
The skymap can be found here: h ttps://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn221226945/quicklook/glg_skymap_all_bn221226945.png
The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn221226945/quicklook/glg_healpix_all_bn221226945.fit
The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn221226945/quicklook/glg_lc_medres34_bn221226945.gif
GCN Circular #33108
S. B. Cenko (GSFC), J.D. Gropp (PSU), J. A. Kennea (PSU), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL) and T. M. Parsotan (GSFC/UMBC/CRESSTII) report on behalf of the Neil Gehrels Swift Observatory Team:
At 22:41:20 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 221226B (trigger=1145959). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 22.917, -41.554 which is
```
   RA(J2000) = 01h 31m 40s
   Dec(J2000) = -41d 33' 13"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multi-peaked structure with a duration of about 10 sec. The peak count rate was ~2200 counts/sec (15-350 keV), at ~1 sec after the trigger.
The XRT began observing the field at 22:42:32.4 UT, 72.4 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source located at RA, Dec 22.90890, -41.52648 which is equivalent to:
```
   RA(J2000)  = 01h 31m 38.14s
   Dec(J2000) = -41d 31' 35.3"
```
with an uncertainty of 3.5 arcseconds (radius, 90% containment). This location is 101 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 consistent with the Galactic value of 1.69 x 10^20 cm^-2 (Willingale et al. 2013).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 75 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers none of the XRT error circle. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.017.
Burst Advocate for this burst is S. B. Cenko (brad.cenko AT nasa.gov). 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:     Mon 26 Dec 22 22:53:28 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1145959,   Seg_Num: 0
POINT_RA:         22.930d {+01h 31m 43s} (J2000)
POINT_DEC:       -41.551d {-41d 33' 03"} (J2000)
ROLL:            241.394d
IMG_START_DATE:  19939 TJD;   360 DOY;   22/12/26
IMG_START_TIME:  81967.78 SOD {22:46:07.78} UT,   287.7 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     693787598
X_OFFSET:        868 [pixels]
Y_OFFSET:        854 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1028
Y_GRB_POS:       1014
BINNING_INDEX:   1
IM_URL:          sw01145959000msuni0318.fits
SUN_POSTN:       275.61d {+18h 22m 26s}  -23.34d {-23d 20' 07"}
SUN_DIST:         86.89 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      328.53d {+21h 54m 08s}  -18.06d {-18d 03' 36"}
MOON_DIST:        51.86 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      275.70,-73.38 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:        0.31,-46.43 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        If you have elected to receive attachments:  
COMMENTS:        The uvot_catalog_image.fits.gz file does not exist; skipping the attachment.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 26 Dec 22 22:54:12 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     1145959,   Seg_Num: 0
GRB_RA:           22.9088d {+01h 31m 38.11s} (J2000),
                  23.1591d {+01h 32m 38.17s} (current),
                  22.3636d {+01h 29m 27.26s} (1950)
GRB_DEC:         -41.5264d {-41d 31' 35.0"} (J2000),
                 -41.4086d {-41d 24' 31.0"} (current),
                 -41.7834d {-41d 47' 00.0"} (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:  19939 TJD;   360 DOY;   22/12/26
IMG_START_TIME:  81772.00 SOD {22:42:52.00} UT,   91.9 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       275.61d {+18h 22m 26s}  -23.34d {-23d 20' 07"}
SUN_DIST:         86.89 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      328.54d {+21h 54m 10s}  -18.06d {-18d 03' 26"}
MOON_DIST:        51.84 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      275.70,-73.41 [deg] galactic lon,lat of the burst
ECL_COORDS:        0.30,-46.40 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 1.1% < P(seren) < 2.8%.

GCN Circular #33109
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team.
Using 1173 s of XRT Photon Counting mode data and 2 UVOT images for GRB 221226B, 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 = 22.90972, -41.52669 which is equivalent to:
```
RA (J2000): 01h 31m 38.33s
Dec (J2000): -41d 31' 36.1"
```
with an uncertainty of 2.6 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 #33110
D. Xu (NAOC), A. Chrimes (Radboud Univ.), B. Schneider (MIT), L. Izzo (DARK/NBI), A. Saccardi (GEPI, Observatoire de Paris), Z.P. Zhu (NAOC, HUST), N.R. Tanvir (Univ. Leicester) report on behalf of the Stargate collaboration:
We observed the field of GRB 221226B detected by Swift (Cenko et al., GCN 33108) and Fermi (Fermi GBM team, GCN 33107) using the ESO VLT UT3 (Melipal) equipped with the X-shooter spectrograph. Our spectra cover the wavelength range 3000-21000 AA, and consist of 4 exposures by 1200 s each.
The observations started at 01:10:06 UT on 2022-12-27, i.e., ~2.48 hr after BAT trigger. The optical afterglow of the burst is detected at coordinates
```
R.A.(J2000) = 01:31:38.036
Dec.(J2000) = - 41:31:37.25
```
with an uncertainty of ~0.3 arcsec and r = 22.0 +/- 0.1 mag, calibrated with Legacy Survey nearby stars.
A broad absorption feature is visible around 4490 AA, which we identify as being due to H I. From detection of multiple absorption features, which we interpret as being due to S II, Si II, O I, C II, Si IV, Al III, NV, and emission features due to [O II] and Hbeta, we infer a common redshift of z = 2.694. We conclude this is the redshift of the burst.
Note that at the optical afterglow position, the Legacy Survey presents an extended source with r = 23.82 mag, which is likely the host galaxy of the burst, being consistent with the the detection of emission features in the X-shooter spectra.
We acknowledge excellent support from the ESO observing staff in Paranal, in particular Pascale Hibon and Ditte Slumstrup.
GCN Circular #33111
M. Capalbi (INAF-IASFPA), M. Perri (SSDC & INAF-OAR), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), D.N. Burrows (PSU), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), V. D'Elia (SSDC & INAF-OAR) and S.B. Cenko report on behalf of the Swift-XRT team:
We have analysed 6.2 ks of XRT data for GRB 221226B (Cenko et al. GCN Circ. 33108), from 56 s to 40.4 ks after the BAT trigger. The data comprise 14 s in Windowed Timing (WT) mode (the first 9 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Goad et al. (GCN Circ. 33109).
The light curve can be modelled with a power-law decay with a decay index of alpha=1.58 (+0.13, -0.12).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.5 (+0.4, -0.3). The best-fitting absorption column is 7 (+23, -7) x 10^21 cm^-2, at a redshift of 2.694, in addition to the Galactic value of 1.7 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.3 x 10^-11 (4.6 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Galactic foreground: 1.7 x 10^20 cm^-2
Intrinsic column:    7 (+23, -7) x 10^21 cm^-2 at z=2.694
Photon index:	     1.5 (+0.4, -0.3)
```
If the light curve continues to decay with a power-law decay index of 1.58, the count rate at T+24 hours will be 6.9 x 10^-5 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.0 x 10^-15 (3.2 x 10^-15) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01145959.
This circular is an official product of the Swift-XRT team.
GCN Circular #33112
S. Lesage (UAH) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team:
"At 22:41:20 UT on 26 December 2022, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 221226B (trigger 693787285/221226945), which was also detected by Swift BAT (S. B. Cenko et al. 2022, GCN 33108) and has a measured redshift from the VLT/X-Shooter (GCN 33110). The Fermi GBM Final Real-time Localization (GCN 33107) is consistent with the Swift BAT position.
The angle from the Fermi LAT boresight is 58 degrees.
The GBM light curve consists of a single emission episode with a duration (T90) of about 5 s (50-300 keV). The time-averaged spectrum from T0+0.002 to T0+2.592 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is 0.2 +/- 0.2 and the cutoff energy, parameterized as Epeak, is 104 +/- 8 keV.
The event fluence (10-1000 keV) in this time interval is (7.8 +/- 0.5)E-07 erg/cm^2. The 1-sec peak photon flux measured starting from T0+0.3 s in the 10-1000 keV band is 4.1 +/- 0.2 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 #33114
N. Klingler (UMBC/NASA-GSFC/CRESST II) reports on behalf of the Swift/UVOT team:
The Swift-UVOT began settled observations of the field of GRB 221226B 76 s after the BAT trigger (Cenko et al., GCN Circ. 33108). A source consistent with the XRT position (Goad et al., GCN Circ. 33109) and consistent with the optical counterpart reported by VLT/X-shooter (Xu et al., GCN Circ. 33110) is detected in the initial UVOT exposures.
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               76          226          147         20.54 +/- 0.22
v                 4408         4608          197        >19.3
b                 3793         3993          197        >20.0
u                  288         5132          278        >20.1
w1                4818         5018          197        >20.0
m2                4613         4813          197        >19.5
w2                4204         4404          197        >20.0
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.017 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #33115
S. Laha (GSFC/UMBC), S. D. Barthelmy (GSFC), S. B. Cenko (GSFC), H. A. Krimm (NSF), A. Y. Lien (U Tampa), C. B. Markwardt (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+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 221226B (trigger #1145959) (Cenko, et al., GCN Circ. 33108). The BAT ground-calculated position is RA, Dec = 22.903, -41.515 deg which is
```
  RA(J2000)  =  01h 31m 36.7s
   Dec(J2000) = -41d 30' 52.5"
```
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 97%.
The mask-weighted light curve shows a pulse of approximately 4 seconds total duration and some substructure. T90 (15-350 keV) is 3.44 +- 0.57 sec (estimated error including systematics).
The time-averaged spectrum from T+0.22 to T+4.28 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.16 +- 0.13. The fluence in the 15-150 keV band is 5.4 +- 0.5 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+0.24 sec in the 15-150 keV band is 2.6 +- 0.3 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/1145959/BA/
GCN Circular #33119
R. Strausbaugh (University of Minnesota), A. Cucchiara (NASA) report on behalf of a larger collaboration:
We observed the GRB 221226B (Cenko et al., GCN 33108) field with the LCOGT 1-meter Sinistro instrument at the South African Astronomical Observatory site, on December 27, from 19:40 to 20:07 UT (corresponding to 20.98 to 21.47 hours from the GRB trigger time) with the SDSS r and i filters.
We performed a series of 3x300s exposures in each band. We do not detect any new sources in the XRT error region, in either band.
The following upper limits are calculated using the SkyMapper catalog as reference:
```
r > 20.75
i > 20.16
```
These magnitudes are not corrected for galactic extinction.

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Jochen Greiner, last update: 28-Dec-2022 [Disclaimer]