Gamma-ray Burst 210226A

(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:     Fri 26 Feb 21 04:54:27 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1034721,   Seg_Num: 0
GRB_RA:          124.138d {+08h 16m 33s} (J2000),
                 124.562d {+08h 18m 15s} (current),
                 123.132d {+08h 12m 32s} (1950)
GRB_DEC:         +57.577d {+57d 34' 38"} (J2000),
                 +57.511d {+57d 30' 39"} (current),
                 +57.732d {+57d 43' 53"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       3526 [cnts]    Image_Peak=241 [image_cnts]
TRIGGER_DUR:     1.024 [sec] 
TRIGGER_INDEX:   149     E_range: 25-100 keV
BKG_INTEN:       18656 [cnts]
BKG_TIME:        17021.42 SOD {04:43:41.42} UT
BKG_DUR:         8 [sec]
GRB_DATE:        19271 TJD;    57 DOY;   21/02/26
GRB_TIME:        17037.23 SOD {04:43:57.23} UT
GRB_PHI:          -8.34 [deg]
GRB_THETA:        41.88 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     22.62 [sigma]
IMAGE_SIGNIF:    11.81 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +2  +1  +0  +0 +55  +0 
SUN_POSTN:       339.49d {+22h 37m 56s}   -8.64d {-08d 38' 14"}
SUN_DIST:        124.20 [deg]   Sun_angle= -9.7 [hr] (East of Sun)
MOON_POSTN:      146.86d {+09h 47m 27s}  +18.17d {+18d 10' 21"}
MOON_DIST:        42.67 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      159.95, 33.92 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      112.05, 36.72 [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 = 258.11,20.11 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 26 Feb 21 04:55:12 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     1034721,   Seg_Num: 0
POINT_RA:        124.115d {+08h 16m 28s} (J2000)
POINT_DEC:       +57.565d {+57d 33' 54"} (J2000)
IMG_START_DATE:  19271 TJD;    57 DOY;   21/02/26
IMG_START_TIME:  17135.34 SOD {04:45:35.34} UT,   98.1 [sec] since BAT Trigger Time
COUNTS:          4    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:     Fri 26 Feb 21 04:56:27 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1034721,   Seg_Num: 0
POINT_RA:        124.115d {+08h 16m 28s} (J2000)
POINT_DEC:       +57.565d {+57d 33' 54"} (J2000)
POINT_ROLL:      316.346d
IMG_START_DATE:  19271 TJD;    57 DOY;   21/02/26
IMG_START_TIME:  17138.88 SOD {04:45:38.88} UT,   101.7 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.781
N_STARS:         28
X_OFFSET:        551 [pixels]
Y_OFFSET:        673 [pixels]
X_MAX:           1510 [pixels]
Y_MAX:           1632 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw01034721000msufc0101.fits
SUN_POSTN:       339.49d {+22h 37m 57s}   -8.64d {-08d 38' 12"}
SUN_DIST:        124.20 [deg]   Sun_angle= -9.7 [hr] (East of Sun)
MOON_POSTN:      146.88d {+09h 47m 32s}  +18.17d {+18d 10' 00"}
MOON_DIST:        42.68 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      159.97, 33.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      112.04, 36.71 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 26 Feb 21 04:56:33 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1034721,   Seg_Num: 0
GRB_RA:          124.138d {+08h 16m 33s} (J2000),
                 124.562d {+08h 18m 15s} (current),
                 123.132d {+08h 12m 32s} (1950)
GRB_DEC:         +57.577d {+57d 34' 38"} (J2000),
                 +57.511d {+57d 30' 39"} (current),
                 +57.732d {+57d 43' 53"} (1950)
GRB_DATE:        19271 TJD;    57 DOY;   21/02/26
GRB_TIME:        17037.23 SOD {04:43:57.23} UT
TRIGGER_INDEX:   149
GRB_PHI:          -8.34 [deg]
GRB_THETA:        41.88 [deg]
DELTA_TIME:      20.00 [sec]
TRIGGER_DUR:     1.024 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     22.62 [sigma]
IMAGE_SIGNIF:    11.81 [sigma]
LC_URL:          sw01034721000msb.lc
SUN_POSTN:       339.49d {+22h 37m 57s}   -8.64d {-08d 38' 12"}
SUN_DIST:        124.20 [deg]   Sun_angle= -9.7 [hr] (East of Sun)
MOON_POSTN:      146.88d {+09h 47m 32s}  +18.17d {+18d 09' 59"}
MOON_DIST:        42.68 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      159.95, 33.92 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      112.05, 36.72 [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 = 258.11,20.11 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 26 Feb 21 04:56:49 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1034721,   Seg_Num: 0
POINT_RA:        124.115d {+08h 16m 28s} (J2000)
POINT_DEC:       +57.565d {+57d 33' 54"} (J2000)
POINT_ROLL:      316.346d
IMG_START_DATE:  19271 TJD;    57 DOY;   21/02/26
IMG_START_TIME:  17138.88 SOD {04:45:38.88} UT,   101.7 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.781
N_STARS:         28
X_OFFSET:        551 [pixels]
Y_OFFSET:        673 [pixels]
X_MAX:           1510 [pixels]
Y_MAX:           1632 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw01034721000msufc0101.fits
SUN_POSTN:       339.49d {+22h 37m 57s}   -8.64d {-08d 38' 12"}
SUN_DIST:        124.20 [deg]   Sun_angle= -9.7 [hr] (East of Sun)
MOON_POSTN:      146.89d {+09h 47m 33s}  +18.17d {+18d 09' 56"}
MOON_DIST:        42.68 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      159.97, 33.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      112.04, 36.71 [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 26 Feb 21 04:58:01 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1034721,   Seg_Num: 0
POINT_RA:        124.115d {+08h 16m 28s} (J2000)
POINT_DEC:       +57.565d {+57d 33' 54"} (J2000)
ROLL:            316.346d
IMG_START_DATE:  19271 TJD;    57 DOY;   21/02/26
IMG_START_TIME:  17138.88 SOD {04:45:38.88} UT,   101.7 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     636007565
X_OFFSET:        870 [pixels]
Y_OFFSET:        992 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1030
Y_GRB_POS:       1152
BINNING_INDEX:   1
IM_URL:          sw01034721000msuni0128.fits
SUN_POSTN:       339.49d {+22h 37m 57s}   -8.64d {-08d 38' 11"}
SUN_DIST:        124.20 [deg]   Sun_angle= -9.7 [hr] (East of Sun)
MOON_POSTN:      146.90d {+09h 47m 36s}  +18.16d {+18d 09' 44"}
MOON_DIST:        42.69 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      159.97, 33.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      112.04, 36.71 [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:     Fri 26 Feb 21 04:58:11 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1034721,   Seg_Num: 0
POINT_RA:        124.115d {+08h 16m 28s} (J2000)
POINT_DEC:       +57.565d {+57d 33' 54"} (J2000)
ROLL:            316.346d
IMG_START_DATE:  19271 TJD;    57 DOY;   21/02/26
IMG_START_TIME:  17138.88 SOD {04:45:38.88} UT,   101.7 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     636007565
X_OFFSET:        870 [pixels]
Y_OFFSET:        992 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1030
Y_GRB_POS:       1152
BINNING_INDEX:   1
IM_URL:          sw01034721000msuni0128.fits
SUN_POSTN:       339.49d {+22h 37m 57s}   -8.64d {-08d 38' 11"}
SUN_DIST:        124.20 [deg]   Sun_angle= -9.7 [hr] (East of Sun)
MOON_POSTN:      146.90d {+09h 47m 36s}  +18.16d {+18d 09' 42"}
MOON_DIST:        42.69 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      159.97, 33.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      112.04, 36.71 [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:     Fri 26 Feb 21 04:58:42 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     1034721,   Seg_Num: 0
GRB_RA:          124.1161d {+08h 16m 27.86s} (J2000),
                 124.5401d {+08h 18m 09.62s} (current),
                 123.1094d {+08h 12m 26.25s} (1950)
GRB_DEC:         +57.5840d {+57d 35' 02.4"} (J2000),
                 +57.5176d {+57d 31' 03.3"} (current),
                 +57.7381d {+57d 44' 17.2"} (1950)
GRB_ERROR:       3.8 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  19271 TJD;    57 DOY;   21/02/26
IMG_START_TIME:  17153.00 SOD {04:45:53.00} UT,   115.8 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       339.49d {+22h 37m 57s}   -8.64d {-08d 38' 10"}
SUN_DIST:        124.19 [deg]   Sun_angle= -9.7 [hr] (East of Sun)
MOON_POSTN:      146.90d {+09h 47m 37s}  +18.16d {+18d 09' 37"}
MOON_DIST:        42.71 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      159.94, 33.91 [deg] galactic lon,lat of the burst
ECL_COORDS:      112.03, 36.73 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.58% < P(seren) < 1.1%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 26 Feb 21 05:07:09 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1034721,   Seg_Num: 0
POINT_RA:        124.114d {+08h 16m 27s} (J2000)
POINT_DEC:       +57.563d {+57d 33' 47"} (J2000)
POINT_ROLL:      316.344d
IMG_START_DATE:  19271 TJD;    57 DOY;   21/02/26
IMG_START_TIME:  17906.24 SOD {04:58:26.24} UT,   869.0 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.794
N_STARS:         76
X_OFFSET:        311 [pixels]
Y_OFFSET:        433 [pixels]
X_MAX:           1750 [pixels]
Y_MAX:           1872 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    6
SL_URL:          sw01034721000msufc0869.fits
SUN_POSTN:       339.49d {+22h 37m 58s}   -8.63d {-08d 38' 02"}
SUN_DIST:        124.20 [deg]   Sun_angle= -9.7 [hr] (East of Sun)
MOON_POSTN:      146.99d {+09h 47m 57s}  +18.14d {+18d 08' 08"}
MOON_DIST:        42.74 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      159.97, 33.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      112.04, 36.71 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 26 Feb 21 05:08:32 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1034721,   Seg_Num: 0
POINT_RA:        124.114d {+08h 16m 27s} (J2000)
POINT_DEC:       +57.563d {+57d 33' 47"} (J2000)
ROLL:            316.344d
IMG_START_DATE:  19271 TJD;    57 DOY;   21/02/26
IMG_START_TIME:  17906.24 SOD {04:58:26.24} UT,   869.0 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     636008332
X_OFFSET:        870 [pixels]
Y_OFFSET:        992 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1030
Y_GRB_POS:       1152
BINNING_INDEX:   1
IM_URL:          sw01034721000msuni0896.fits
SUN_POSTN:       339.49d {+22h 37m 59s}   -8.63d {-08d 38' 01"}
SUN_DIST:        124.20 [deg]   Sun_angle= -9.7 [hr] (East of Sun)
MOON_POSTN:      147.00d {+09h 48m 00s}  +18.13d {+18d 07' 54"}
MOON_DIST:        42.75 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      159.97, 33.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      112.04, 36.71 [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:     Fri 26 Feb 21 05:07:25 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1034721,   Seg_Num: 0
POINT_RA:        124.114d {+08h 16m 27s} (J2000)
POINT_DEC:       +57.563d {+57d 33' 47"} (J2000)
POINT_ROLL:      316.344d
IMG_START_DATE:  19271 TJD;    57 DOY;   21/02/26
IMG_START_TIME:  17906.24 SOD {04:58:26.24} UT,   869.0 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.794
N_STARS:         76
X_OFFSET:        311 [pixels]
Y_OFFSET:        433 [pixels]
X_MAX:           1750 [pixels]
Y_MAX:           1872 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    6
SL_URL:          sw01034721000msufc0869.fits
SUN_POSTN:       339.49d {+22h 37m 58s}   -8.63d {-08d 38' 02"}
SUN_DIST:        124.20 [deg]   Sun_angle= -9.7 [hr] (East of Sun)
MOON_POSTN:      146.99d {+09h 47m 57s}  +18.13d {+18d 08' 06"}
MOON_DIST:        42.74 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      159.97, 33.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      112.04, 36.71 [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 26 Feb 21 05:07:34 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     1034721,   Seg_Num: 0
GRB_RA:          124.1144d {+08h 16m 27.45s} (J2000),
                 124.5384d {+08h 18m 09.22s} (current),
                 123.1077d {+08h 12m 25.84s} (1950)
GRB_DEC:         +57.5838d {+57d 35' 01.6"} (J2000),
                 +57.5174d {+57d 31' 02.5"} (current),
                 +57.7379d {+57d 44' 16.5"} (1950)
GRB_ERROR:       2.1 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  19271 TJD;    57 DOY;   21/02/26
IMG_START_TIME:  17153.00 SOD {04:45:53.00} UT,   115.8 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       339.49d {+22h 37m 58s}   -8.63d {-08d 38' 02"}
SUN_DIST:        124.18 [deg]   Sun_angle= -9.7 [hr] (East of Sun)
MOON_POSTN:      146.99d {+09h 47m 58s}  +18.13d {+18d 08' 04"}
MOON_DIST:        42.76 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      159.94, 33.91 [deg] galactic lon,lat of the burst
ECL_COORDS:      112.03, 36.73 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        This is an Update Notice -- the RA,Dec values herein supersede the previous XRT_POS Notice.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        This position was enhanced using UVOT field astrometry.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.58% < P(seren) < 1.1%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 26 Feb 21 05:08:44 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1034721,   Seg_Num: 0
POINT_RA:        124.114d {+08h 16m 27s} (J2000)
POINT_DEC:       +57.563d {+57d 33' 47"} (J2000)
ROLL:            316.344d
IMG_START_DATE:  19271 TJD;    57 DOY;   21/02/26
IMG_START_TIME:  17906.24 SOD {04:58:26.24} UT,   869.0 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     636008332
X_OFFSET:        870 [pixels]
Y_OFFSET:        992 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1030
Y_GRB_POS:       1152
BINNING_INDEX:   1
IM_URL:          sw01034721000msuni0896.fits
SUN_POSTN:       339.49d {+22h 37m 59s}   -8.63d {-08d 38' 01"}
SUN_DIST:        124.20 [deg]   Sun_angle= -9.7 [hr] (East of Sun)
MOON_POSTN:      147.00d {+09h 48m 00s}  +18.13d {+18d 07' 52"}
MOON_DIST:        42.75 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      159.97, 33.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      112.04, 36.71 [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 #29568
A. P. Beardmore (U Leicester), N. J. Klingler (PSU), K. L. Page (U Leicester), D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team:
At 04:43:57 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 210226A (trigger=1034721). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 124.138, +57.577 which is
```
   RA(J2000) = 08h 16m 33s
   Dec(J2000) = +57d 34' 38"
```
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 ~3400 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 04:45:35.3 UT, 98.1 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 124.1144, 57.5839 which is equivalent to:
```
   RA(J2000)  = 08h 16m 27.46s
   Dec(J2000) = +57d 35' 02.2"
```
with an uncertainty of 2.1 arcseconds (radius, 90% containment). This location is 51 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at https://www.swift.ac.uk/sper.
A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (5.24 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 3.2 (+1.84/-1.67) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 101 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.048.
Burst Advocate for this burst is A. P. Beardmore (apb AT star.le.ac.uk). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/)
GCN Circular #29570
Martin Jelinek, Jan Strobl, Rene Hudec and Cyril Polasek (ASU CAS Ondrejov, CZ), report:
The 0.2 m Small Binocular Telescope (BART/SBT) of Ondrejov observatory in Czech republic reacted robotically to the alert of GRB 210226A (Beardmore et al, GCNC 29568), obtaining a series of 12 s unfiltered images starting at 04:54:55.8 UT, i.e. 659 s post trigger.
We do not detect any new source within the XRT errorbox neither in single images (3-sigma limit r'(AB) > ~14.0) nor in a combined 30 x 12 s frame (mean exp time 1033 s post trigger, 3-sigma limit r'(AB) > ~15.8) as calibrated against the Atlas catalog (Tonry et al. ApJ 867, 105, 2018).
GCN Circular #29571
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team.
Using 1421 s of XRT Photon Counting mode data and 3 UVOT images for GRB 210226A, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 124.11528, +57.58394 which is equivalent to:
```
RA (J2000): 08h 16m 27.67s
Dec (J2000): +57d 35' 02.2"
```
with an uncertainty of 1.5 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177).
This circular was automatically generated, and is an official product of the Swift-XRT team.
GCN Circular #29572
```
TITLE:   GCN CIRCULAR
NUMBER:  29572
SUBJECT: GRB 210226A: Burke-Gaffney Observatory optical upper limit
DATE:    21/02/26 15:11:19 GMT
FROM:    Filipp Dmitrievich Romanov at Amateur astronomer  
```
I observed the field of GRB 210226A (Beardmore et al., GCN Circ. 29568) with remote telescope (0.61-m f/6.5 Corrected Dall-Kirkham + CCD) of Burke-Gaffney Observatory (Halifax, Canada). Image (clear: without filter) with 180 seconds exposure time was obtained on 2021-02-26. Start time of exposure: 08:00:36 UT (3 h. 16 m. 39 s. after trigger). I did not detect any optical transients (magnitude limit of about 18.0). Image available here: http://www.ap.smu.ca/~bgo/sm/id.php?app=0&id=13614
GCN Circular #29574
V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D.Kuvshinov, D. Cheryasov (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, O.Ershova (Irkutsk State University, API),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
V. Yurkov, A. Gabovich, Yu. Sergienko (Blagoveschensk Educational State University)
MASTER-Tavrida robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, SAI Crimea astronomical station) was pointed to the Swift GRB 210226A ( A. P. Beardmore et al., GCN 29568) errorbox 42015 sec after notice time and 42682 sec after trigger time at 2021-02-26 16:35:20 UT, with upper limit up to 17.3 mag. Observations started at twilight. The observations began at zenith distance = 30 deg. The sun altitude is -13.1 deg.
The galactic latitude b = 34 deg., longitude l = 160 deg.

Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1556267
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

   42773 |      MASTER-Tavrida |   C |   180 | 17.3 |        
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
GCN Circular #29575
M. Capalbi (INAF-IASFPA), M. Perri (SSDC & INAF-OAR), V. D'Elia (SSDC & INAF-OAR), A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), D.N. Burrows (PSU), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester) and A.P. Beardmore report on behalf of the Swift-XRT team:
We have analysed 6.2 ks of XRT data for GRB 210226A (Beardmore et al. GCN Circ. 29568), from 101 s to 39.3 ks after the BAT trigger. The data comprise 12 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. 29571).
The light curve can be modelled with a series of power-law decays. The initial decay index is alpha=1.0 (+0.3, -0.4). At T+423 s the decay flattens to an alpha of -0.3 (+0.4, -1.1) before breaking again at T+1011 s to a final decay with index alpha=1.14 (+0.09, -0.08).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.96 (+0.18, -0.17). The best-fitting absorption column is 1.9 (+/-0.6) x 10^21 cm^-2, in excess of the Galactic value of 5.2 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 3.6 x 10^-11 (4.7 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     1.9 (+/-0.6) x 10^21 cm^-2
Galactic foreground: 5.2 x 10^20 cm^-2
Excess significance: 4.0 sigma
Photon index:	     1.96 (+0.18, -0.17)
```
If the light curve continues to decay with a power-law decay index of 1.14, the count rate at T+24 hours will be 4.5 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.6 x 10^-13 (2.1 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/01034721.
This circular is an official product of the Swift-XRT team.
GCN Circular #29576
WeiKang Zheng and Alexei V. Filippenko (UC Berkeley) report on behalf of the KAIT GRB team:
The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at Lick Observatory, responded to Swift GRB 210226A (Beardmore et al., GCN 29568) starting at 04:56:15 UT, 738s after the burst.
Observations were performed with an automatic sequence in the clear (roughly R), V, and I filters, and the exposure time was 20s per image. We do not detect any optical afterglow candidate within the enhanced XRT position error circle (Goad et al., GCN 29571), neither in single image, nor in the co-add images. The typical limiting magnitude of our single clear image is about 19.0 mag calibrated to the USNOB1.0 catalog. Our result is consistent with the optical upper limit reported by other groups (Jelinek et al., GCN 29570; Romanov, GCN 29572; Lipunov et al., GCN 29574).
GCN Circular #29578
J. Wood (NASA/MSFC) and C. Meegan (UAH) report on behalf of the Fermi GBM Team:
"At 04:43:56.56 UT on 26 February 2021, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 210226A (trigger 636007441 / 210226197) which was also detected by the Swift/BAT and Swift/XRT (A.P. Beardmore et al. 2019, GCN 29568). The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 58.6 degrees.
The GBM light curve consists of a single peak with a duration (T90) of about 26 s (50-300 keV). The time-averaged spectrum from T0-6 s to T0+18 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.2 +/- 0.1 and the cutoff energy, parameterized as Epeak, is 170 +/- 29 keV
The event fluence (10-1000 keV) in this time interval is (2.7 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+1.2 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 #29579
S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (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 210226A (trigger #1034721) (Beardmore, et al., GCN Circ. 29568). The BAT ground-calculated position is RA, Dec = 124.153, 57.585 deg which is
```
   RA(J2000)  =  08h 16m 36.7s
   Dec(J2000) = +57d 35' 06.9"
```
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 47%.
The BAT light curve showed a complex structure with a duration of about ~30 sec. T90 (15-350 keV) is 20.80 +- 1.68 sec (estimated error including systematics).
The time-averaged spectrum from T-1.92 to T+20.95 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.44 +- 0.15. The fluence in the 15-150 keV band is 1.2 +- 0.1 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+0.02 sec in the 15-150 keV band is 2.8 +- 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/1034721/BA/
GCN Circular #29590
N. P. M. Kuin (UCL-MSSL) and A. P. Beardmore (U. Leicester) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 210226A 102 s after the BAT trigger (Beardmore et al., GCN Circ. 29568). No optical afterglow consistent with the XRT position (Beardmore et al. GCN Circ. 29568) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC           102          251          147         >20.9
u_FC               314          563          246         >20.4
white              102         1192          353         >21.4
v                  643         1236           72         >19.1
b                  569         1167           58         >19.9
u                  314         5121          463         >20.5
w1                 692         4935          236         >20.4
m2                4530         4730          197         >20.0
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.049 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #29656
H. Kumar(IITB), K. Sharma (IITB), U. Stanzin (IAO), A. Dutta(IIA), V. Bhalerao(IITB), G. C. Anupama(IIA), S. Barway(IIA) report on behalf of the GIT team:
We observed GRB 210226A detected by Swift-BAT (A. P. Beardmore et al., GCN 29568) with 0.7m GROWTH-India Telescope (GIT). We obtained 10 exposures of 300 sec each in the r' filter. We did not detect any new source in our stacked image within the 1.5 arcsec circle around R.A.= 08h 16m 27.67s, DEC.=+57d 35' 02.2". The obtained upper limit follows as:
-------------------------------------------------------------------
JD (mid) | T_mid-T0(hrs) | Exposure (sec) | Filter | Lim_mag (5-sigma) |
-------------------------------------------------------------------
2459272.1074 | 9.84 | 3000 (stacked) | r' | > 20.34 |
-------------------------------------------------------------------
The magnitudes are calibrated against PanSTARRS (Flewelling et al., 2018) and not corrected for galactic extinction.
The GROWTH India Telescope (GIT) is a 70-cm telescope with a 0.7 degree field of view, set up by the Indian Institute of Astrophysics and the Indian Institute of Technology Bombay with support from the Indo-US Science and Technology Forum (IUSSTF) and the Science and Engineering Research Board (SERB) of the Department of Science and Technology (DST), Government of India (https://sites.google.com/view/growthindia/). It is located at the Indian Astronomical Observatory (Hanle), operated by the Indian Institute of Astrophysics (IIA).

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Jochen Greiner, last update: 15-Mar-2021 [Disclaimer]