Gamma-ray Burst 210112A

(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:     Tue 12 Jan 21 01:41:15 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1016881,   Seg_Num: 0
GRB_RA:          218.999d {+14h 36m 00s} (J2000),
                 219.220d {+14h 36m 53s} (current),
                 218.472d {+14h 33m 53s} (1950)
GRB_DEC:         +33.070d {+33d 04' 13"} (J2000),
                 +32.979d {+32d 58' 46"} (current),
                 +33.287d {+33d 17' 15"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       3067 [cnts]    Image_Peak=225 [image_cnts]
TRIGGER_DUR:     1.024 [sec]
TRIGGER_INDEX:   146     E_range: 25-100 keV
BKG_INTEN:       15489 [cnts]
BKG_TIME:        5805.68 SOD {01:36:45.68} UT
BKG_DUR:         8 [sec]
GRB_DATE:        19226 TJD;    12 DOY;   21/01/12
GRB_TIME:        5823.79 SOD {01:37:03.79} UT
GRB_PHI:          -1.89 [deg]
GRB_THETA:        24.25 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     22.80 [sigma]
IMAGE_SIGNIF:    10.89 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +2  +0  +0  +0  +0  +0
SUN_POSTN:       293.84d {+19h 35m 21s}  -21.63d {-21d 37' 41"}
SUN_DIST:         89.64 [deg]   Sun_angle= 5.0 [hr] (West of Sun)
MOON_POSTN:      278.07d {+18h 32m 16s}  -24.91d {-24d 54' 45"}
MOON_DIST:        80.54 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:       54.05, 66.69 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      202.28, 45.27 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Coordinates.
COMMENTS:        This Notice was delayed by more than 60 sec past the end of the trigger integration interval;
COMMENTS:        probably due to it occurring during a Malindi downlink session.
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 = 15.09,12.48 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 12 Jan 21 01:41:56 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     1016881,   Seg_Num: 0
GRB_RA:          219.0044d {+14h 36m 01.0s} (J2000),
                 219.2259d {+14h 36m 54.2s} (current),
                 218.4777d {+14h 33m 54.6s} (1950)
GRB_DEC:         +33.0566d {+33d 03' 23.7"} (J2000),
                 +32.9658d {+32d 57' 56.7"} (current),
                 +33.2738d {+33d 16' 25.5"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       70 [cnts]
IMG_START_DATE:  19226 TJD;    12 DOY;   21/01/12
IMG_START_TIME:  5898.04 SOD {01:38:18.04} UT,   74.2 [sec] since BAT Trigger Time
CENTROID_X:      278.51,  raw= 279  [pixels]
CENTROID_Y:      288.76,  raw= 289  [pixels]
ROLL:            116.19 [deg]
GAIN:            2
MODE:            2, Short Image mode
WAVEFORM:        134
EXPO_TIME:       0.10 [sec]
GRB_POS_XRT_Y:   -22.00
GRB_POS_XRT_Z:   -68.09
IMAGE_URL:       sw01016881000msxps_rw.img
SUN_POSTN:       293.84d {+19h 35m 21s}  -21.63d {-21d 37' 41"}
SUN_DIST:         89.63 [deg]   Sun_angle= 5.0 [hr] (West of Sun)
MOON_POSTN:      278.07d {+18h 32m 18s}  -24.91d {-24d 54' 46"}
MOON_DIST:        80.54 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:       54.02, 66.68 [deg] galactic lon,lat of the burst
ECL_COORDS:      202.29, 45.26 [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:     Tue 12 Jan 21 01:42:00 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     1016881,   Seg_Num: 0
GRB_RA:          219.0044d {+14h 36m 01.0s} (J2000),
                 219.2259d {+14h 36m 54.2s} (current),
                 218.4777d {+14h 33m 54.6s} (1950)
GRB_DEC:         +33.0566d {+33d 03' 23.7"} (J2000),
                 +32.9658d {+32d 57' 56.7"} (current),
                 +33.2738d {+33d 16' 25.5"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       70 [cnts]
IMG_START_DATE:  19226 TJD;    12 DOY;   21/01/12
IMG_START_TIME:  5898.04 SOD {01:38:18.04} UT,   74.2 [sec] since BAT Trigger Time
CENTROID_X:      278.51,  raw= 279  [pixels]
CENTROID_Y:      288.76,  raw= 289  [pixels]
ROLL:            116.19 [deg]
GAIN:            2
MODE:            2, Short Image mode
WAVEFORM:        134
EXPO_TIME:       0.10 [sec]
GRB_POS_XRT_Y:   -22.00
GRB_POS_XRT_Z:   -68.09
IMAGE_URL:       sw01016881000msxps_rw.img
SUN_POSTN:       293.84d {+19h 35m 21s}  -21.63d {-21d 37' 41"}
SUN_DIST:         89.63 [deg]   Sun_angle= 5.0 [hr] (West of Sun)
MOON_POSTN:      278.08d {+18h 32m 18s}  -24.91d {-24d 54' 46"}
MOON_DIST:        80.54 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:       54.02, 66.68 [deg] galactic lon,lat of the burst
ECL_COORDS:      202.29, 45.26 [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:     Tue 12 Jan 21 01:42:13 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1016881,   Seg_Num: 0
GRB_RA:          218.999d {+14h 36m 00s} (J2000),
                 219.220d {+14h 36m 53s} (current),
                 218.472d {+14h 33m 53s} (1950)
GRB_DEC:         +33.070d {+33d 04' 13"} (J2000),
                 +32.979d {+32d 58' 46"} (current),
                 +33.287d {+33d 17' 15"} (1950)
GRB_DATE:        19226 TJD;    12 DOY;   21/01/12
GRB_TIME:        5823.79 SOD {01:37:03.79} UT
TRIGGER_INDEX:   146
GRB_PHI:          -1.89 [deg]
GRB_THETA:        24.25 [deg]
DELTA_TIME:      -51.00 [sec]
TRIGGER_DUR:     1.024 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     22.80 [sigma]
IMAGE_SIGNIF:    10.89 [sigma]
LC_URL:          sw01016881000msb.lc
SUN_POSTN:       293.84d {+19h 35m 21s}  -21.63d {-21d 37' 41"}
SUN_DIST:         89.64 [deg]   Sun_angle= 5.0 [hr] (West of Sun)
MOON_POSTN:      278.08d {+18h 32m 19s}  -24.91d {-24d 54' 46"}
MOON_DIST:        80.55 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:       54.05, 66.69 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      202.28, 45.27 [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 = 15.09,12.48 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 12 Jan 21 01:42:32 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1016881,   Seg_Num: 0
POINT_RA:        218.986d {+14h 35m 57s} (J2000)
POINT_DEC:       +33.067d {+33d 04' 02"} (J2000)
POINT_ROLL:      116.186d
IMG_START_DATE:  19226 TJD;    12 DOY;   21/01/12
IMG_START_TIME:  5906.71 SOD {01:38:26.71} UT,   82.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.672
N_STARS:         24
X_OFFSET:        520 [pixels]
Y_OFFSET:        504 [pixels]
X_MAX:           1479 [pixels]
Y_MAX:           1463 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw01016881000msufc0082.fits
SUN_POSTN:       293.84d {+19h 35m 21s}  -21.63d {-21d 37' 40"}
SUN_DIST:         89.65 [deg]   Sun_angle= 5.0 [hr] (West of Sun)
MOON_POSTN:      278.08d {+18h 32m 20s}  -24.91d {-24d 54' 46"}
MOON_DIST:        80.56 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:       54.05, 66.70 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      202.27, 45.26 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 12 Jan 21 01:41:46 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     1016881,   Seg_Num: 0
GRB_RA:          219.0044d {+14h 36m 01.05s} (J2000),
                 219.2259d {+14h 36m 54.21s} (current),
                 218.4777d {+14h 33m 54.65s} (1950)
GRB_DEC:         +33.0566d {+33d 03' 23.7"} (J2000),
                 +32.9658d {+32d 57' 56.7"} (current),
                 +33.2738d {+33d 16' 25.5"} (1950)
GRB_ERROR:       5.0 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       7.10e-08 [erg/cm2/sec]
GRB_SIGNIF:      8.36 [sigma]
IMG_START_DATE:  19226 TJD;    12 DOY;   21/01/12
IMG_START_TIME:  5898.04 SOD {01:38:18.04} UT,   74.2 [sec] since BAT Trigger Time
TAM[0-3]:        327.65 237.18 261.61 243.54
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       293.84d {+19h 35m 21s}  -21.63d {-21d 37' 41"}
SUN_DIST:         89.63 [deg]   Sun_angle= 5.0 [hr] (West of Sun)
MOON_POSTN:      278.07d {+18h 32m 18s}  -24.91d {-24d 54' 45"}
MOON_DIST:        80.54 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:       54.02, 66.68 [deg] galactic lon,lat of the burst
ECL_COORDS:      202.29, 45.26 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 0.85 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:     Tue 12 Jan 21 01:42:45 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1016881,   Seg_Num: 0
POINT_RA:        218.986d {+14h 35m 57s} (J2000)
POINT_DEC:       +33.067d {+33d 04' 02"} (J2000)
POINT_ROLL:      116.186d
IMG_START_DATE:  19226 TJD;    12 DOY;   21/01/12
IMG_START_TIME:  5906.71 SOD {01:38:26.71} UT,   82.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.672
N_STARS:         24
X_OFFSET:        520 [pixels]
Y_OFFSET:        504 [pixels]
X_MAX:           1479 [pixels]
Y_MAX:           1463 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw01016881000msufc0082.fits
SUN_POSTN:       293.84d {+19h 35m 21s}  -21.63d {-21d 37' 40"}
SUN_DIST:         89.65 [deg]   Sun_angle= 5.0 [hr] (West of Sun)
MOON_POSTN:      278.08d {+18h 32m 20s}  -24.91d {-24d 54' 46"}
MOON_DIST:        80.56 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:       54.05, 66.70 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      202.27, 45.26 [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:     Tue 12 Jan 21 01:43:50 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1016881,   Seg_Num: 0
POINT_RA:        218.986d {+14h 35m 57s} (J2000)
POINT_DEC:       +33.067d {+33d 04' 02"} (J2000)
ROLL:            116.186d
IMG_START_DATE:  19226 TJD;    12 DOY;   21/01/12
IMG_START_TIME:  5906.71 SOD {01:38:26.71} UT,   82.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     632108333
X_OFFSET:        938 [pixels]
Y_OFFSET:        848 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1098
Y_GRB_POS:       1008
BINNING_INDEX:   1
IM_URL:          sw01016881000msuni0109.fits
SUN_POSTN:       293.84d {+19h 35m 22s}  -21.63d {-21d 37' 40"}
SUN_DIST:         89.65 [deg]   Sun_angle= 5.0 [hr] (West of Sun)
MOON_POSTN:      278.10d {+18h 32m 23s}  -24.91d {-24d 54' 47"}
MOON_DIST:        80.57 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:       54.05, 66.70 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      202.27, 45.26 [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:     Tue 12 Jan 21 01:44:03 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1016881,   Seg_Num: 0
POINT_RA:        218.986d {+14h 35m 57s} (J2000)
POINT_DEC:       +33.067d {+33d 04' 02"} (J2000)
ROLL:            116.186d
IMG_START_DATE:  19226 TJD;    12 DOY;   21/01/12
IMG_START_TIME:  5906.71 SOD {01:38:26.71} UT,   82.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     632108333
X_OFFSET:        938 [pixels]
Y_OFFSET:        848 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1098
Y_GRB_POS:       1008
BINNING_INDEX:   1
IM_URL:          sw01016881000msuni0109.fits
SUN_POSTN:       293.84d {+19h 35m 22s}  -21.63d {-21d 37' 40"}
SUN_DIST:         89.65 [deg]   Sun_angle= 5.0 [hr] (West of Sun)
MOON_POSTN:      278.10d {+18h 32m 23s}  -24.91d {-24d 54' 48"}
MOON_DIST:        80.57 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:       54.05, 66.70 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      202.27, 45.26 [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:     Tue 12 Jan 21 01:45:52 UT
NOTICE_TYPE:     Swift-UVOT Position
TRIGGER_NUM:     1016881,   Seg_Num: 0
GRB_RA:          219.0060d {+14h 36m 01.44s} (J2000),
                 219.2275d {+14h 36m 54.59s} (current),
                 218.4793d {+14h 33m 55.03s} (1950)
GRB_DEC:         +33.0542d {+33d 03' 15.1"} (J2000),
                 +32.9634d {+32d 57' 48.0"} (current),
                 +33.2713d {+33d 16' 16.8"} (1950)
GRB_ERROR:       0.7 [arcsec radius, statistical only]
GRB_MAG:         19.52 +/- 0.16 [mag]
FILTER:          10, White
IMG_START_DATE:  19226 TJD;    12 DOY;   21/01/12
IMG_START_TIME:  5903.00 SOD {01:38:23.00} UT,   79.2 [sec] since BAT Trigger Time
SUN_POSTN:       293.84d {+19h 35m 22s}  -21.63d {-21d 37' 39"}
SUN_DIST:         89.63 [deg]   Sun_angle= 5.0 [hr] (West of Sun)
MOON_POSTN:      278.12d {+18h 32m 28s}  -24.91d {-24d 54' 50"}
MOON_DIST:        80.56 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:       54.01, 66.68 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      202.29, 45.26 [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 9.7 arcsec from the XRT position.  
COMMENTS:        Result based on Genie data.  
COMMENTS:        Notice generated automatically.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 12 Jan 21 01:48:38 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1016881,   Seg_Num: 0
POINT_RA:        218.987d {+14h 35m 57s} (J2000)
POINT_DEC:       +33.071d {+33d 04' 14"} (J2000)
POINT_ROLL:      116.185d
IMG_START_DATE:  19226 TJD;    12 DOY;   21/01/12
IMG_START_TIME:  6119.65 SOD {01:41:59.65} UT,   295.9 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.731
N_STARS:         12
X_OFFSET:        618 [pixels]
Y_OFFSET:        528 [pixels]
X_MAX:           1577 [pixels]
Y_MAX:           1487 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    3
SL_URL:          sw01016881000msufc0295.fits
SUN_POSTN:       293.84d {+19h 35m 22s}  -21.63d {-21d 37' 38"}
SUN_DIST:         89.66 [deg]   Sun_angle= 5.0 [hr] (West of Sun)
MOON_POSTN:      278.15d {+18h 32m 35s}  -24.91d {-24d 54' 52"}
MOON_DIST:        80.61 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:       54.06, 66.70 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      202.26, 45.26 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 12 Jan 21 01:54:34 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1016881,   Seg_Num: 0
POINT_RA:        218.988d {+14h 35m 57s} (J2000)
POINT_DEC:       +33.071d {+33d 04' 14"} (J2000)
POINT_ROLL:      116.185d
IMG_START_DATE:  19226 TJD;    12 DOY;   21/01/12
IMG_START_TIME:  6695.84 SOD {01:51:35.84} UT,   872.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        5.295
N_STARS:         44
X_OFFSET:        378 [pixels]
Y_OFFSET:        288 [pixels]
X_MAX:           1817 [pixels]
Y_MAX:           1727 [pixels]
DET_THRESH:      19
PHOTO_THRESH:    11
SL_URL:          sw01016881000msufc0872.fits
SUN_POSTN:       293.85d {+19h 35m 24s}  -21.63d {-21d 37' 35"}
SUN_DIST:         89.66 [deg]   Sun_angle= 5.0 [hr] (West of Sun)
MOON_POSTN:      278.21d {+18h 32m 51s}  -24.92d {-24d 54' 58"}
MOON_DIST:        80.65 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:       54.06, 66.70 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      202.26, 45.26 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 12 Jan 21 01:54:48 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1016881,   Seg_Num: 0
POINT_RA:        218.988d {+14h 35m 57s} (J2000)
POINT_DEC:       +33.071d {+33d 04' 14"} (J2000)
POINT_ROLL:      116.185d
IMG_START_DATE:  19226 TJD;    12 DOY;   21/01/12
IMG_START_TIME:  6695.84 SOD {01:51:35.84} UT,   872.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        5.295
N_STARS:         44
X_OFFSET:        378 [pixels]
Y_OFFSET:        288 [pixels]
X_MAX:           1817 [pixels]
Y_MAX:           1727 [pixels]
DET_THRESH:      19
PHOTO_THRESH:    11
SL_URL:          sw01016881000msufc0872.fits
SUN_POSTN:       293.85d {+19h 35m 24s}  -21.63d {-21d 37' 35"}
SUN_DIST:         89.66 [deg]   Sun_angle= 5.0 [hr] (West of Sun)
MOON_POSTN:      278.21d {+18h 32m 52s}  -24.92d {-24d 54' 59"}
MOON_DIST:        80.65 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:       54.06, 66.70 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      202.26, 45.26 [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:     Tue 12 Jan 21 01:56:00 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1016881,   Seg_Num: 0
POINT_RA:        218.988d {+14h 35m 57s} (J2000)
POINT_DEC:       +33.071d {+33d 04' 14"} (J2000)
ROLL:            116.185d
IMG_START_DATE:  19226 TJD;    12 DOY;   21/01/12
IMG_START_TIME:  6695.84 SOD {01:51:35.84} UT,   872.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     632109122
X_OFFSET:        937 [pixels]
Y_OFFSET:        847 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1097
Y_GRB_POS:       1007
BINNING_INDEX:   1
IM_URL:          sw01016881000msuni0899.fits
SUN_POSTN:       293.85d {+19h 35m 24s}  -21.63d {-21d 37' 35"}
SUN_DIST:         89.66 [deg]   Sun_angle= 5.0 [hr] (West of Sun)
MOON_POSTN:      278.23d {+18h 32m 55s}  -24.92d {-24d 55' 00"}
MOON_DIST:        80.66 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:       54.06, 66.70 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      202.26, 45.26 [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:     Tue 12 Jan 21 01:56:09 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1016881,   Seg_Num: 0
POINT_RA:        218.988d {+14h 35m 57s} (J2000)
POINT_DEC:       +33.071d {+33d 04' 14"} (J2000)
ROLL:            116.185d
IMG_START_DATE:  19226 TJD;    12 DOY;   21/01/12
IMG_START_TIME:  6695.84 SOD {01:51:35.84} UT,   872.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     632109122
X_OFFSET:        937 [pixels]
Y_OFFSET:        847 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1097
Y_GRB_POS:       1007
BINNING_INDEX:   1
IM_URL:          sw01016881000msuni0899.fits
SUN_POSTN:       293.85d {+19h 35m 24s}  -21.63d {-21d 37' 35"}
SUN_DIST:         89.66 [deg]   Sun_angle= 5.0 [hr] (West of Sun)
MOON_POSTN:      278.23d {+18h 32m 55s}  -24.92d {-24d 55' 00"}
MOON_DIST:        80.66 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:       54.06, 66.70 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      202.26, 45.26 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN Circular #29289
E. Ambrosi (INAF-IASFPA), S. D. Barthelmy (GSFC), A. D'Ai (INAF-IASFPA), V. D'Elia (SSDC), J. A. Kennea (PSU), N. J. Klingler (PSU), S. Laha (GSFC/UMBC/CRESST), A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team:
At 01:37:03 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 210112A (trigger=1016881). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 218.999, +33.070 which is
```
   RA(J2000)  =  14h 36m 00s
   Dec(J2000) = +33d 04' 13"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows multiple peaks with the larger peak at T+70 sec and duration of ~150 sec. The peak count rate was ~20800 counts/sec (15-350 keV), at ~68 sec after the trigger.
The XRT began observing the field at 01:38:18.0 UT, 74.2 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 219.0044, 33.0566 which is equivalent to:
```
   RA(J2000)  = 14h 36m 1.06s
   Dec(J2000) = +33d 03' 23.8"
```
with an uncertainty of 5.0 arcseconds (radius, 90% containment). This location is 50 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy.
The initial flux in the 0.1 s image was 7.10e-08 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 82 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at
```
  RA(J2000)  =	14:36:01.45 = 219.00606
  DEC(J2000) = +33:03:15.4  =  33.05428
```
with a 90%-confidence error radius of about 0.66 arc sec. This position is 9.8 arc sec. from the center of the XRT error circle. The estimated magnitude is 19.52 with a 1-sigma error of about 0.16. No correction has been made for the expected extinction corresponding to E(B-V) of 0.014.
Burst Advocate for this burst is E. Ambrosi (elena.ambrosi 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:     Tue 12 Jan 21 01:49:45 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1016881,   Seg_Num: 0
POINT_RA:        218.987d {+14h 35m 57s} (J2000)
POINT_DEC:       +33.071d {+33d 04' 14"} (J2000)
ROLL:            116.185d
IMG_START_DATE:  19226 TJD;    12 DOY;   21/01/12
IMG_START_TIME:  6119.65 SOD {01:41:59.65} UT,   295.9 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     632108545
X_OFFSET:        938 [pixels]
Y_OFFSET:        848 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1098
Y_GRB_POS:       1008
BINNING_INDEX:   1
IM_URL:          sw01016881000msuni0322.fits
SUN_POSTN:       293.84d {+19h 35m 23s}  -21.63d {-21d 37' 37"}
SUN_DIST:         89.66 [deg]   Sun_angle= 5.0 [hr] (West of Sun)
MOON_POSTN:      278.16d {+18h 32m 38s}  -24.92d {-24d 54' 53"}
MOON_DIST:        80.61 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:       54.06, 66.70 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      202.26, 45.26 [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:     Tue 12 Jan 21 01:49:59 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1016881,   Seg_Num: 0
POINT_RA:        218.987d {+14h 35m 57s} (J2000)
POINT_DEC:       +33.071d {+33d 04' 14"} (J2000)
ROLL:            116.185d
IMG_START_DATE:  19226 TJD;    12 DOY;   21/01/12
IMG_START_TIME:  6119.65 SOD {01:41:59.65} UT,   295.9 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     632108545
X_OFFSET:        938 [pixels]
Y_OFFSET:        848 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1098
Y_GRB_POS:       1008
BINNING_INDEX:   1
IM_URL:          sw01016881000msuni0322.fits
SUN_POSTN:       293.84d {+19h 35m 23s}  -21.63d {-21d 37' 37"}
SUN_DIST:         89.66 [deg]   Sun_angle= 5.0 [hr] (West of Sun)
MOON_POSTN:      278.16d {+18h 32m 39s}  -24.92d {-24d 54' 54"}
MOON_DIST:        80.62 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:       54.06, 66.70 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      202.26, 45.26 [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:     Tue 12 Jan 21 01:48:50 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1016881,   Seg_Num: 0
POINT_RA:        218.987d {+14h 35m 57s} (J2000)
POINT_DEC:       +33.071d {+33d 04' 14"} (J2000)
POINT_ROLL:      116.185d
IMG_START_DATE:  19226 TJD;    12 DOY;   21/01/12
IMG_START_TIME:  6119.65 SOD {01:41:59.65} UT,   295.9 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.731
N_STARS:         12
X_OFFSET:        618 [pixels]
Y_OFFSET:        528 [pixels]
X_MAX:           1577 [pixels]
Y_MAX:           1487 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    3
SL_URL:          sw01016881000msufc0295.fits
SUN_POSTN:       293.84d {+19h 35m 23s}  -21.63d {-21d 37' 38"}
SUN_DIST:         89.66 [deg]   Sun_angle= 5.0 [hr] (West of Sun)
MOON_POSTN:      278.15d {+18h 32m 36s}  -24.91d {-24d 54' 53"}
MOON_DIST:        80.61 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:       54.06, 66.70 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      202.26, 45.26 [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:     Tue 12 Jan 21 02:16:48 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     1016881,   Seg_Num: 0
GRB_RA:          219.0049d {+14h 36m 01.17s} (J2000),
                 219.2264d {+14h 36m 54.33s} (current),
                 218.4782d {+14h 33m 54.77s} (1950)
GRB_DEC:         +33.0548d {+33d 03' 17.2"} (J2000),
                 +32.9640d {+32d 57' 50.2"} (current),
                 +33.2719d {+33d 16' 19.0"} (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:  19226 TJD;    12 DOY;   21/01/12
IMG_START_TIME:  6762.00 SOD {01:52:42.00} UT,   938.2 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       293.86d {+19h 35m 28s}  -21.62d {-21d 37' 26"}
SUN_DIST:         89.65 [deg]   Sun_angle= 5.0 [hr] (West of Sun)
MOON_POSTN:      278.45d {+18h 33m 49s}  -24.92d {-24d 55' 20"}
MOON_DIST:        80.79 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:       54.01, 66.68 [deg] galactic lon,lat of the burst
ECL_COORDS:      202.29, 45.26 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        This is an Update Notice -- the RA,Dec values herein supersede the previous XRT_POS Notice.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.11% < P(seren) < 0.58%.

GCN Circular #29290
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team.
Using 579 s of XRT Photon Counting mode data and 1 UVOT images for GRB 210112A, 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 = 219.00603, +33.05415 which is equivalent to:
```
RA (J2000): 14h 36m 1.45s
Dec (J2000): +33d 03' 15.0"
```
with an uncertainty of 1.7 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 #29292
A. Novichonok (Petrozavodsk State University, KIAM), S. Belkin (IKI), A. Pozanenko (IKI), Sh. Ehgamberdiev (UBAI) report on behalf of GRB IKI FuN:
We observed the field of GRB 210112A (Ambrosi et al., GCN 29289) with Kitab-ISON RC-36 telescope starting on 2021-01-12 (UT) 01:54:30, i.e. 447 seconds after trigger in Clear filter. We do not detect the afterglow candidate (Ambrosi et al., GCN 29289) within enhanced Swift-XRT position (Goad et al., GCN 29290). Preliminary photometry of the field is following
```
Date,      UT start, t-T0,   Exp.,  Filter,  OT,   Err., UL
                     (mid, days)
2021-01-12  01:54:30  0.01541 11*30 CR       n/d   n/d   18.5
```
The photometry is based on nearby USNO-B1.0 stars
```
USNO-B1.0_id R2
1231-0260671 14:35:00.70080 +33:06:09.4428 14.32
1229-0281658 14:34:57.67344 +32:58:13.0800 14.75
```
At 01:37:03 UT
GCN Circular #29293
A. Ursi, M. Cardillo (INAF/IAPS), C. Pittori (SSDC, and INAF/OAR), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), A. Argan, C. Casentini, Y. Evangelista, G. Piano (INAF/IAPS), F. Lucarelli, F. Verrecchia (SSDC, and INAF/OAR), A. Bulgarelli, V. Fioretti, F. Fuschino, N. Parmiggiani (INAF/OAS-Bologna), M. Marisaldi (INAF/OAS-Bologna, and Bergen University), M. Pilia, A. Trois (INAF/OA-Cagliari), I. Donnarumma (ASI), F. Longo (Univ. Trieste and INFN Trieste), A. Giuliani (INAF/IASF-Mi), report on behalf of the AGILE Team:
The AGILE satellite detected GRB 210112A, reported by Swift (GCNs #29289, #29290), at T0 = 2021-01-12 01:37:58 (UT).
The event is clearly visible in the scientific ratemeters of the SuperAGILE (SA; 18-60 keV), MiniCALorimeter (MCAL; 0.4-100 MeV), and AntiCoincidence (AC; 50-200 keV) detectors. The burst lasted about 25 s and released 1120 counts in the SA detector (above a background rate of 60 Hz), 25140 counts in the MCAL detector (above a background rate of 1250 Hz), and 71500 counts in the AC detector (above a background rate of 3570 Hz). The AGILE ratemeters light curves can be found at: http://www.agilescienceapp.it/notices/GRB210112A_AGILE_RM.png .
Additional analysis of AGILE data is in progress.
GCN Circular #29295
P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), M. Capalbi (INAF-IASFPA), M. Perri (SSDC & INAF-OAR), B. Sbarufatti (PSU), D.N. Burrows (PSU), J. D. Gropp (PSU), K.L. Page (U. Leicester) and E. Ambrosi report on behalf of the Swift-XRT team:
We have analysed 8.5 ks of XRT data for GRB 210112A (Ambrosi et al. GCN Circ. 29289), from 77 s to 46.0 ks after the BAT trigger. The data comprise 859 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Goad et al. (GCN Circ. 29290).
The late-time light curve (from T0+6.4 ks) can be modelled with a power-law decay with a decay index of alpha=1.36 (+/-0.06).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.56 (+/-0.03). The best-fitting absorption column is 2.34 (+/-0.14) x 10^21 cm^-2, in excess of the Galactic value of 9.5 x 10^19 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 2.01 (+0.10, -0.09) and a best-fitting absorption column of 2.8 (+/-0.4) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.7 x 10^-11 (5.1 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     2.8 (+/-0.4) x 10^21 cm^-2
Galactic foreground: 9.5 x 10^19 cm^-2
Excess significance: 12.3 sigma
Photon index:	     2.01 (+0.10, -0.09)
```
If the light curve continues to decay with a power-law decay index of 1.36, the count rate at T+24 hours will be 0.046 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.7 x 10^-12 (2.3 x 10^-12) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01016881.
This circular is an official product of the Swift-XRT team.
GCN Circular #29296
D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), C. C. Thoene (HETH), M. Blazek, J. F. Agui Fernandez (both HETH/IAA-CSIC), and A. Sota (IAA-CSIC) report:
We observed the optical afterglow of GRB 210112A (Swfit detection: Ambrosi et al., GCN #29289; AGILE Detection: Ursi et al., GCN #29293) with the 1.5m telescope of the Observatorio de Sierra Nevada (OSN), Granada, Spain. We obtained 12 x 90 s exposures in B, Rc, Ic and 11 x 90 s in V, between 2021-01-12 04:03:22.52 and 2021-01-12 05:21:34.99 UT. The afterglow is detected In the combined image of each band.
At 0.12587 days after the GRB, we measure Rc = 22.41 +/- 0.12 mag (AB mag, vs. a several nearby SDSS stars converted to Rc following the Lupton transformations, then transformed back to AB mag).
A preliminary analysis of all data reveals peculiar colors, the Rc - Ic color is large, whereas the colors between B, V, and Rc are quite flat. There is no source detected in either SDSS or PanSTARRS at the afterglow position, so this is probably not due to influence of the host galaxy. However, we are able to fit this SED with a large (A_V > 1 mag) amount of Milky-Way like dust at a redshift of z ~ 2 and an intrinsic slope in agreement with the one derived from X-ray observations. Such high extinction would be in line with the significant excess column density seen in the XRT observations (Evans et al., GCN #29295).
GCN Circular #29297
M. Stamatikos (OSU), E. Ambrosi (INAF-IASFPA), S. D. Barthelmy (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 210112A (trigger #1016881) (Ambrosi et al., GCN Circ. 29289). The BAT ground-calculated position is RA, Dec = 219.005, 33.058 deg which is
```
   RA(J2000)  =  14h 36m 01.3s
   Dec(J2000) = +33d 03' 30.4"
```
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 89%.
The mask-weighted light curve shows a multi-peaked structure that starts at ~T-10 s and ends at ~T+220 s. The three main peaks occur at ~T+1 s, ~T+70 s, and ~T+105 s, respectively, and the one at ~T+70 s is the largest peak. T90 (15-350 keV) is 107.60 +- 13.02 sec (estimated error including systematics).
The time-averaged spectrum from T-10.44 to T+218.47 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.45 +- 0.03. The fluence in the 15-150 keV band is 2.33 +- 0.03 x 10^-5 erg/cm2. The 1-sec peak photon flux measured from T+68.86 sec in the 15-150 keV band is 20.5 +- 0.6 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/1016881/BA/
GCN Circular #29300
D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), C. C. Thoene (HETH), M. Blazek, J. F. Agui Fernandez (both HETH/IAA-CSIC), and A. Sota (IAA-CSIC) report:
We observed again the optical afterglow of GRB 210112A (Swfit detection: Ambrosi et al., GCN #29289; AGILE Detection: Ursi et al., GCN #29293) with the 1.5m telescope of the Observatorio de Sierra Nevada (OSN), Granada, Spain. We obtained 3 x 450 s exposures in B, V, Rc each, and 8 x 150 s in Ic, between 2021-01-13 04:29:28.99 and 2021-01-13 05:55:34.35 UT. The afterglow is now only detected in the combined Ic-band image. Together with the observations of the day before (Kann et al., GCN #29296), we measure (against the same SDSS comparison stars as before, in Vega mags):
Ic = 20.65 +/- 0.075 mag at 0.12587 days.
Ic = 22.57 +/- 0.217 mag at 1.12739 days.
This implies a decay index of alpha ~ 0.8.
GCN Circular #29301
Rahul Gupta (ARIES), Amit Kumar (ARIES), Dimple (ARIES), Ankur Ghosh (ARIES), Krishan Chand (ARIES), Amar Aryan (ARIES), Shashi B. Pandey (ARIES), and Kuntal Misra (ARIES) report:
We observed the filed of Swift and AGILE detected GRB 210112A (Ambrosi et al., GCN 29289; and Ursi et al., GCN 29293) with 1.3m Devasthal Fast Optical Telescope (DFOT) located at Devasthal observatory of Aryabhatta Research Institute of Observational Sciences (ARIES), India. The observations were started on 2021-01-13 at 00:06:18 UT i.e. ~ 22.49 hours after the BAT trigger. We have taken multiple frames having an exposure time of 120 s in the R filter. We do not detect the optical afterglow candidate (Ambrosi et al., GCN 29289; and Kann et al., GCN 29296) within enhanced Swift-XRT position (Goad et al., GCN 29290).
We obtain the following 3-sigma upper limits in the stacked image.
```
Date Start_UT    T_start-T0 (hrs)        Filter   Exp time (s)
Limiting Magnitude

============================================================
2021-01-13   00:18:18      22.69              R              120*12
           > 22.0
```
The magnitude is not corrected for the Galactic extinction in the direction of the burst. Photometric calibration is performed using the standard stars from the USNO-B1.0 catalogue.
This circular may be cited.
GCN Circular #29302
N. Pankov (HSE), A. Pozanenko (IKI), E. Klunko (ISTP), S. Belkin (IKI) report on behalf of GRB IKI FuN:
We observed the field of GRB 210112A (Ambrosi et al., GCN 29289; Ursi et al., GCN #9293) with AZT-33IK telescope of Sayan observatory (Mondy) starting on 2021-01-12 (UT) 20:41:40. The optical afterglow (Ambrosi et al., GCN 29289; Kann et al., GCNs 29296, 29300) is not detected in stacked image in R-filter. The non detection of the afterlow is consistent with other non-detections in R-filter (Novichonok et al., GCN 29292; Gupta et al., GCN 29301).
Preliminary photometry of the optical transient in a combined image is following
```
Date       UT start   t-T0       Filter Exp.    OT    Err.  UL(3sigma)
                       (mid, days)        (s)

2021-01-12 20:41:40   0.80738    R      18*120   n/d  n/d   22.4
```
The photometry is based on the nearby USNO-B1.0 stars.
GCN Circular #29303
M. H. Siegel (PSU) and Ambrosi (INAF-IASFPA) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 210112A 83 s after the BAT trigger (Ambrosi et al., GCN Circ. 29289). A source consistent with the XRT position (Goad et al. GCN Circ. 29290) is detected in the initial UVOT exposures.
The preliminary UVOT position is:
```
  RA  (J2000) =  14:36:01.49 = 219.00619 (deg.)
  Dec (J2000) = +33:03:15.3  =  33.05424 (deg.)
```
with an estimated uncertainty of 0.50 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               83          233          147         19.54 +/- 0.10
v                  626         1419           97        >18.5
b                  551         1517           97        >19.1
u                  296         1493          304        >20.2
w1                 675         1468           78        >19.1
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.014 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #29315
D. Svinkin, S. Golenetskii, D. Frederiks, M. Ulanov, A. Tsvetkova, A. Lysenko, A. Ridnaia, and T. Cline on behalf of the Konus-Wind team, report:
The long-duration GRB 210112A (Swift-BAT detection: Ambrosi et al., GCN Circ. 29289; AGILE detection: Ursi et al., GCN Circ. 29293) triggered Konus-Wind at T0=5886.553 s UT (01:38:06.553).
The burst light curve shows a multipeaked structure which starts at ~T0-73 s and has a total duration of ~143 s. The emission is seen up to ~5 MeV.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB210112_T05886
As observed by Konus-Wind, the burst had a fluence of 6.72(-0.65,+0.72)x10^-5 erg/cm2, and a 64-ms peak flux, measured from T0+7.856 s, of 1.02(-0.18,+0.19)x10^-5 erg/cm2/s (both in the 20 keV - 16 MeV energy range).
The time-averaged spectrum of the burst (measured from T0 to T0+68.608 s) is best fit in the 20 keV - 16 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.96(-0.08,+0.08), the high energy photon index beta = -2.71(-0.53,+0.25), the peak energy Ep = 214(-16,+18) keV (chi2 = 87/97 dof).
The spectrum near the maximum count rate (measured from T0+7.168 s to T0+9.216 s) is best fit in the 20 keV - 16 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.85(-0.12,+0.13), the high energy photon index beta = -2.67(-0.57,+0.27), the peak energy Ep = 219(-25,+28) keV (chi2 = 38/65 dof).
All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.
GCN Circular #29319
D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), C. C. Thoene (HETH), M. Blazek, J. F. Agui Fernandez (both HETH/IAA-CSIC), and J. I. Vico Linares (CAHA) report:
We observed the afterglow position (Ambrosi et al., GCN #29289) of the bright Swift GRB 210112A (Swift detection: Ambrosi et al., GCN #29289; AGILE detection: Ursi et al., GCN #29293; Konus-Wind detection: Svinkin et al., GCN #29315) with CAFOS at the 2.2m telescope at Calar Alto, Almeria, Spain, in the Ic band. We obtained 10 x 360 s exposures, centered at 5.1696 days after the GRB, under good conditions but mediocre seeing.
The afterglow (Kann et al., GCNs #29296,29300; Siegel et al., GCN #29303) is faintly detected. We measure Ic = 23.69 +/- 0.24 mag. (AB mag, vs. a several nearby SDSS stars converted to Ic following the Lupton transformations, then transformed back to AB mag).
This magnitude lies slightly above the extrapolation of the decay found during the first two epochs (Kann et al., GCN #29300) and may indicate an underlying host galaxy. Indeed we also see another faint, possibly extended source about 2" to the East, at RA (J2000) = 14:36:01.453, Dec. (J2000) = +33:03:13.40, which may be the host galaxy or a system interacting with it. However, the rough redshift estimate of z ~ 2 (Kann et al., GCN #29296) would imply this must be a very luminous system, or a foreground interloper.
GCN Circular #29326
C. Zheng, C. Cai, J. C. Liu, Q. Luo, S. Xiao, W. C. Xue, Q. B. Yi, Y. Q. Zhang, Y. Huang, C. K. Li, G. Li, X. B. Li, J. Y. Liao, X. Y. Song, S. L. Xiong, C. Z. Liu, X. F. Li, Z. W. Li, Z. Chang, A. M. Zhang, Y. F. Zhang, X. F. Lu, C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, M. Wu, Y. P. Xu, S. N. Zhang (IHEP), report on behalf of the Insight-HXMT team:
At 2021-01-12T01:38:13.400 (T0), Insight-HXMT/HE detected GRB 210112A (trigger ID: HEB210112068) in a routine search of the data, which also triggered Swift/BAT (E. Ambrosi (INAF-IASFPA) et al. ,GCN #29289).
The Insight-HXMT/HE light curve mainly consists of multiple pulses with a duration (T90) of 12.27 s measured from T0+0.91 s. The 1-ms peak rate, measured from T0+7.63 s, is 2134 cnts/sec. The total counts from this burst is 213416252 counts. URL_LC: http://twiki.ihep.ac.cn/pub/HXMT/GRBList/HEB210112068_lc.jpg
All measurements above are made with the CsI detectors operating in the regular mode with the energy range of about 80-800 keV (deposited energy). Only gamma-rays with energy greater than about 200 keV can penetrate the spacecraft and leave signals in the CsI detectors installed inside of the telescope.
Insight-HXMT is the first Chinese space X-ray telescope, which was funded jointly by the China National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS). More information about it could be found at: http://www.hxmt.org.
GCN Circular #29333
Dimple (ARIES), K. Misra (ARIES), A. Ghosh (ARIES), R. Gupta (ARIES), A. Kumar (ARIES), S.B. Pandey (ARIES) report:
We carried out the follow-up observations of GRB 210112A (Ambrosi et al. GCN #29289) with Aries Devasthal Faint Object Spectrograph and Camera (ADFOSC) mounted on the 3.6m Devasthal Optical Telescope (DOT) at Devasthal observatory of Aryabhatta Research Institute of observational sciencES (ARIES), India. The observations started on 2021-01-13 at 23:59:18 UT in i-band (sdss). We observed a series of 6 images with an exposure time of 300 seconds each. We detect the afterglow at 1.933 days after the burst, reported by Ambrosi et al. GCN #29289; Ursi et al. GCN #29293; Kann et al. GCNs #29296,29300; Siegel et al. GCN #29303, in i-band with a magnitude of 23.19 +- 0.166 (AB mag), calibrated with the nearby PanSTARRS field. Our results are consistent with the power-law decay index of 0.8 reported by Kann et al. #29296.
The magnitude is not corrected for Galactic extinction in the direction of the burst.
GCN Circular #29456
A. Rossi (INAF-OAS), on behalf of the CIBO collaboration, and D. A. Kann (HETH/IAA-CSIC) report:
We observed the field of GRB210112A (Ambrosi et al., GCN #29289; Ursi et al., GCN #29293; Svinkin et al., GCN #29315) simultaneously in the r' and z' bands with the LBC imager mounted on the Large Binocular Telescope (LBT, Mt. Graham, AZ, USA). We obtained 20 min of imaging on 2021-02-05, 24.3 days after the burst trigger. Observations were performed under mediocre seeing conditions and reached a depth of r' ~ 26 mag.
At the position of the afterglow (Ambrosi et al., GCN #29289), we clearly detect the host galaxy in both filters and we measure the following AB magnitudes:
```
r' = 23.96 +/- 0.15 mag,
z' = 23.38 +/- 0.15 mag.
```
calibrated against SDSS field stars.
Therefore, we confirm that the flattening observed by Kann et al. (GCN #29319) was due to the host component.
However, we do not see the faint object detected by Kann et al. at RA, Dec. = 14:36:01.453, +33:03:13.40 (J2000). We have investigated the CAHA and OSN (Kann et al., GCN 29296) images and found that the source detected by Kann et al., GCN 29319, which should have been "South" of the afterglow position, not "East", is the actual afterglow (with the fainter, northern extension possibly stemming from image distortion or a slight mismatch when co-adding frames), the offset stemming from a small arcsecond-scale astrometry mismatch. For the afterglow position, we measure Ic = 23.52 � 0.19 mag (AB), replacing the value given in GCN #29319. We estimate the underlying host to be Ic ~ 23.7 mag (AB) from the LBT photometry.
Correlating the OSN image with the LBT image, we find an afterglow position of RA, Dec. = 14:36:01.492 +33:03:14.945 (J2000), with errors of 0".2 in each coordinate, calibrated against Gaia DR2, in good agreement with the UVOT position (Ambrosi et al., GCN #29289).
In the LBT image, we furthermore detect a second, fainter, but probably also extended source just 2" north-north-east of the host (at RA, Dec. =14:36:01.54 +33:03:18.7; J2000) with r' = 24.5 � 0.2 mag. It is unclear if this likely galaxy is related to the host galaxy.
We acknowledge the excellent support from the LBTO and LBT-INAF staff, particularly B. Rothberg and D. Paris, in obtaining these observations.

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Jochen Greiner, last update: 10-Feb-2021 [Disclaimer]