Gamma-ray Burst 210308A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 08 Mar 21 06:38:12 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1036227,   Seg_Num: 0
GRB_RA:          67.088d {+04h 28m 21s} (J2000),
                 67.443d {+04h 29m 46s} (current),
                 66.253d {+04h 25m 01s} (1950)
GRB_DEC:         +37.411d {+37d 24' 39"} (J2000),
                 +37.456d {+37d 27' 23"} (current),
                 +37.300d {+37d 18' 02"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       1647 [cnts]    Image_Peak=112 [image_cnts]
TRIGGER_DUR:     0.512 [sec]
TRIGGER_INDEX:   69     E_range: 15-50 keV
BKG_INTEN:       17239 [cnts]
BKG_TIME:        23861.36 SOD {06:37:41.36} UT
BKG_DUR:         8 [sec]
GRB_DATE:        19281 TJD;    67 DOY;   21/03/08
GRB_TIME:        23876.85 SOD {06:37:56.85} UT
GRB_PHI:         -147.15 [deg]
GRB_THETA:        44.95 [deg]
SOLN_STATUS:     0x20000003
RATE_SIGNIF:     19.33 [sigma]
IMAGE_SIGNIF:    8.39 [sigma]
MERIT_PARAMS:     +1  +0  +0  -1  +1  -1  +0  +1 -11  +0
SUN_POSTN:       348.88d {+23h 15m 32s}   -4.78d {-04d 46' 35"}  
SUN_DIST:         83.90 [deg]   Sun_angle= -5.2 [hr] (East of Sun)
MOON_POSTN:      287.61d {+19h 10m 27s}  -25.06d {-25d 03' 19"}
MOON_DIST:       143.81 [deg]
MOON_ILLUM:      27 [%]
GAL_COORDS:      163.51, -7.83 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       71.29, 15.45 [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 = 170.09,20.31 [deg].
COMMENTS:
COMMENTS:        NOTE: This BAT event is temporally(0.0<100sec) coincident with the FERMI_GBM event (trignum=636878281).

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 08 Mar 21 06:38:22 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      49
TRIGGER_NUM:     636878281
GRB_RA:           64.550d {+04h 18m 12s} (J2000),
                  64.893d {+04h 19m 34s} (current),
                  63.742d {+04h 14m 58s} (1950)
GRB_DEC:         +33.900d {+33d 53' 60"} (J2000),
                 +33.950d {+33d 57' 01"} (current),
                 +33.779d {+33d 46' 43"} (1950)
GRB_ERROR:       9.33 [deg radius, statistical plus systematic]
GRB_INTEN:       155 [cnts/sec]
DATA_SIGNIF:     11.90 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        19281 TJD;    67 DOY;   21/03/08
GRB_TIME:        23876.91 SOD {06:37:56.91} UT
GRB_PHI:          60.00 [deg]
GRB_THETA:        30.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      1.86
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      84%  GRB
2nd_MOST_LIKELY:  13%  Generic SGR
DETECTORS:       1,1,0, 0,0,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       348.88d {+23h 15m 32s}   -4.78d {-04d 46' 34"}
SUN_DIST:         81.18 [deg]   Sun_angle= -5.1 [hr] (East of Sun)
MOON_POSTN:      287.61d {+19h 10m 27s}  -25.06d {-25d 03' 18"}
MOON_DIST:       142.05 [deg]
MOON_ILLUM:      27 [%]
GAL_COORDS:      164.63,-11.75 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       68.59, 12.33 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210308276/quicklook/glg_lc_medres34_bn210308276.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 222.15,11.30 [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=1036227).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 08 Mar 21 06:38:30 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      60
TRIGGER_NUM:     636878281
GRB_RA:           66.450d {+04h 25m 48s} (J2000),
                  66.808d {+04h 27m 14s} (current),
                  65.606d {+04h 22m 25s} (1950)
GRB_DEC:         +38.733d {+38d 43' 60"} (J2000),
                 +38.780d {+38d 46' 48"} (current),
                 +38.620d {+38d 37' 13"} (1950)
GRB_ERROR:       4.90 [deg radius, statistical plus systematic]
GRB_INTEN:       1076 [cnts/sec]
DATA_SIGNIF:     77.80 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        19281 TJD;    67 DOY;   21/03/08
GRB_TIME:        23876.91 SOD {06:37:56.91} UT
GRB_PHI:          60.00 [deg]
GRB_THETA:        25.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      0.88
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      84%  GRB
2nd_MOST_LIKELY:  14%  GRO_J0422_32
DETECTORS:       1,1,0, 0,0,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       348.88d {+23h 15m 32s}   -4.78d {-04d 46' 34"}
SUN_DIST:         83.66 [deg]   Sun_angle= -5.2 [hr] (East of Sun)
MOON_POSTN:      287.61d {+19h 10m 28s}  -25.06d {-25d 03' 18"}
MOON_DIST:       143.11 [deg]
MOON_ILLUM:      27 [%]
GAL_COORDS:      162.20, -7.28 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       71.00, 16.83 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210308276/quicklook/glg_lc_medres34_bn210308276.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 222.15,11.30 [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=1036227).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 08 Mar 21 06:38:41 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      59
TRIGGER_NUM:     636878281
GRB_RA:           63.480d {+04h 13m 55s} (J2000),
                  63.849d {+04h 15m 24s} (current),
                  62.610d {+04h 10m 26s} (1950)
GRB_DEC:         +42.830d {+42d 49' 48"} (J2000),
                 +42.882d {+42d 52' 56"} (current),
                 +42.704d {+42d 42' 14"} (1950)
GRB_ERROR:       1.62 [deg radius, statistical only]
DATA_SIGNIF:     89.70 [sigma]
DATA_INTERVAL:   2.048 [sec]
GRB_DATE:        19281 TJD;    67 DOY;   21/03/08
GRB_TIME:        23876.91 SOD {06:37:56.91} UT
GRB_PHI:          51.00 [deg]
GRB_THETA:        22.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4173 (Gnd S/W Version number)
SUN_POSTN:       348.88d {+23h 15m 32s}   -4.78d {-04d 46' 34"}
SUN_DIST:         82.37 [deg]   Sun_angle= -5.0 [hr] (East of Sun)
MOON_POSTN:      287.62d {+19h 10m 28s}  -25.06d {-25d 03' 18"}
MOON_DIST:       140.13 [deg]
MOON_ILLUM:      27 [%]
GAL_COORDS:      157.68, -5.98 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       69.43, 21.27 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210308276/quicklook/glg_lc_medres34_bn210308276.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_636878281.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=1036227).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 08 Mar 21 06:39:14 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      0
TRIGGER_NUM:     636878281
GRB_RA:           63.450d {+04h 13m 48s} (J2000),
                  63.819d {+04h 15m 17s} (current),
                  62.580d {+04h 10m 19s} (1950)
GRB_DEC:         +42.770d {+42d 46' 12"} (J2000),
                 +42.822d {+42d 49' 21"} (current),
                 +42.644d {+42d 38' 37"} (1950)
GRB_ERROR:       1.18 [deg radius, statistical only]
DATA_SIGNIF:     43.10 [sigma]
DATA_INTERVAL:   3.072 [sec]
GRB_DATE:        19281 TJD;    67 DOY;   21/03/08
GRB_TIME:        23876.91 SOD {06:37:56.91} UT
GRB_PHI:          51.00 [deg]
GRB_THETA:        22.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41731 (Gnd S/W Version number)
SUN_POSTN:       348.89d {+23h 15m 32s}   -4.78d {-04d 46' 34"}
SUN_DIST:         82.33 [deg]   Sun_angle= -5.0 [hr] (East of Sun)
MOON_POSTN:      287.62d {+19h 10m 29s}  -25.06d {-25d 03' 17"}
MOON_DIST:       140.12 [deg]
MOON_ILLUM:      27 [%]
GAL_COORDS:      157.71, -6.03 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       69.39, 21.21 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210308276/quicklook/glg_lc_medres34_bn210308276.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_636878281.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        In the LAT Field-of-view.  
COMMENTS:        This is likely a Long GRB.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file will not be created/available until ~15 min after the trigger.  
COMMENTS:        The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(0.0<100sec) coincident with the SWIFT_BAT event (trignum=1036227).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 08 Mar 21 06:39:46 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     1036227,   Seg_Num: 0
GRB_RA:           67.0767d {+04h 28m 18.40s} (J2000),
                  67.4314d {+04h 29m 43.54s} (current),
                  66.2409d {+04h 24m 57.81s} (1950)
GRB_DEC:         +37.4346d {+37d 26' 04.5"} (J2000),
                 +37.4802d {+37d 28' 48.7"} (current),
                 +37.3243d {+37d 19' 27.4"} (1950)
GRB_ERROR:       6.3 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       5.18e-10 [erg/cm2/sec]
GRB_SIGNIF:      4.89 [sigma]
IMG_START_DATE:  19281 TJD;    67 DOY;   21/03/08
IMG_START_TIME:  23961.81 SOD {06:39:21.81} UT,   85.0 [sec] since BAT Trigger Time
TAM[0-3]:        327.66 237.17 261.61 243.42
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       348.89d {+23h 15m 33s}   -4.78d {-04d 46' 33"}
SUN_DIST:         83.89 [deg]   Sun_angle= -5.2 [hr] (East of Sun)
MOON_POSTN:      287.63d {+19h 10m 31s}  -25.05d {-25d 03' 16"}
MOON_DIST:       143.78 [deg]
MOON_ILLUM:      27 [%]
GAL_COORDS:      163.49, -7.82 [deg] galactic lon,lat of the burst
ECL_COORDS:       71.28, 15.47 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.
COMMENTS:        The XRT position is 1.54 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 08 Mar 21 06:39:56 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     1036227,   Seg_Num: 0
GRB_RA:           67.0767d {+04h 28m 18.4s} (J2000),
                  67.4314d {+04h 29m 43.5s} (current),
                  66.2409d {+04h 24m 57.8s} (1950)
GRB_DEC:         +37.4346d {+37d 26' 04.5"} (J2000),
                 +37.4802d {+37d 28' 48.7"} (current),
                 +37.3243d {+37d 19' 27.4"} (1950)
GRB_ERROR:       6.1 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       24 [cnts]
IMG_START_DATE:  19281 TJD;    67 DOY;   21/03/08
IMG_START_TIME:  23961.81 SOD {06:39:21.81} UT,   85.0 [sec] since BAT Trigger Time
CENTROID_X:      273.80,  raw= 274  [pixels]
CENTROID_Y:      269.71,  raw= 270  [pixels]
ROLL:            259.00 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -66.91
GRB_POS_XRT_Z:   -79.19
IMAGE_URL:       sw01036227000msxps_rw.img
SUN_POSTN:       348.89d {+23h 15m 33s}   -4.78d {-04d 46' 33"}
SUN_DIST:         83.89 [deg]   Sun_angle= -5.2 [hr] (East of Sun)
MOON_POSTN:      287.63d {+19h 10m 31s}  -25.05d {-25d 03' 16"}
MOON_DIST:       143.78 [deg]
MOON_ILLUM:      27 [%]
GAL_COORDS:      163.49, -7.82 [deg] galactic lon,lat of the burst
ECL_COORDS:       71.28, 15.47 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 08 Mar 21 06:39:58 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     1036227,   Seg_Num: 0
GRB_RA:           67.0767d {+04h 28m 18.4s} (J2000),
                  67.4314d {+04h 29m 43.5s} (current),
                  66.2409d {+04h 24m 57.8s} (1950)
GRB_DEC:         +37.4346d {+37d 26' 04.5"} (J2000),
                 +37.4802d {+37d 28' 48.7"} (current),
                 +37.3243d {+37d 19' 27.4"} (1950)
GRB_ERROR:       6.1 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       24 [cnts]
IMG_START_DATE:  19281 TJD;    67 DOY;   21/03/08
IMG_START_TIME:  23961.81 SOD {06:39:21.81} UT,   85.0 [sec] since BAT Trigger Time
CENTROID_X:      273.80,  raw= 274  [pixels]
CENTROID_Y:      269.71,  raw= 270  [pixels]
ROLL:            259.00 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -66.91
GRB_POS_XRT_Z:   -79.19
IMAGE_URL:       sw01036227000msxps_rw.img
SUN_POSTN:       348.89d {+23h 15m 33s}   -4.78d {-04d 46' 33"}
SUN_DIST:         83.89 [deg]   Sun_angle= -5.2 [hr] (East of Sun)
MOON_POSTN:      287.63d {+19h 10m 31s}  -25.05d {-25d 03' 16"}
MOON_DIST:       143.78 [deg]
MOON_ILLUM:      27 [%]
GAL_COORDS:      163.49, -7.82 [deg] galactic lon,lat of the burst
ECL_COORDS:       71.28, 15.47 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 08 Mar 21 06:41:24 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1036227,   Seg_Num: 0
GRB_RA:           67.088d {+04h 28m 21s} (J2000),
                  67.443d {+04h 29m 46s} (current),
                  66.253d {+04h 25m 01s} (1950)
GRB_DEC:         +37.411d {+37d 24' 39"} (J2000),
                 +37.456d {+37d 27' 23"} (current),
                 +37.300d {+37d 18' 02"} (1950)
GRB_DATE:        19281 TJD;    67 DOY;   21/03/08
GRB_TIME:        23876.85 SOD {06:37:56.85} UT
TRIGGER_INDEX:   69
GRB_PHI:         -147.15 [deg]
GRB_THETA:        44.95 [deg]
DELTA_TIME:      52.00 [sec]
TRIGGER_DUR:     0.512 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     19.33 [sigma]
IMAGE_SIGNIF:    8.39 [sigma]
LC_URL:          sw01036227000msb.lc
SUN_POSTN:       348.89d {+23h 15m 33s}   -4.78d {-04d 46' 31"}
SUN_DIST:         83.90 [deg]   Sun_angle= -5.2 [hr] (East of Sun)
MOON_POSTN:      287.64d {+19h 10m 35s}  -25.05d {-25d 03' 14"}
MOON_DIST:       143.78 [deg]
MOON_ILLUM:      26 [%]
GAL_COORDS:      163.51, -7.83 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       71.29, 15.45 [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 = 170.09,20.31 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 08 Mar 21 06:42:26 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1036227,   Seg_Num: 0
POINT_RA:         67.108d {+04h 28m 26s} (J2000)
POINT_DEC:       +37.420d {+37d 25' 11"} (J2000)
POINT_ROLL:      258.999d
IMG_START_DATE:  19281 TJD;    67 DOY;   21/03/08
IMG_START_TIME:  23971.41 SOD {06:39:31.41} UT,   94.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.630
N_STARS:         54
X_OFFSET:        576 [pixels]
Y_OFFSET:        440 [pixels]
X_MAX:           1535 [pixels]
Y_MAX:           1399 [pixels]
DET_THRESH:      16
PHOTO_THRESH:    9
SL_URL:          sw01036227000msufc0094.fits
SUN_POSTN:       348.89d {+23h 15m 33s}   -4.78d {-04d 46' 30"}
SUN_DIST:         83.91 [deg]   Sun_angle= -5.2 [hr] (East of Sun)
MOON_POSTN:      287.66d {+19h 10m 37s}  -25.05d {-25d 03' 13"}
MOON_DIST:       143.79 [deg]
MOON_ILLUM:      26 [%]
GAL_COORDS:      163.52, -7.81 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       71.31, 15.45 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 08 Mar 21 06:42:37 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1036227,   Seg_Num: 0
POINT_RA:         67.108d {+04h 28m 26s} (J2000)
POINT_DEC:       +37.420d {+37d 25' 11"} (J2000)
POINT_ROLL:      258.999d
IMG_START_DATE:  19281 TJD;    67 DOY;   21/03/08
IMG_START_TIME:  23971.41 SOD {06:39:31.41} UT,   94.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.630
N_STARS:         54
X_OFFSET:        576 [pixels]
Y_OFFSET:        440 [pixels]
X_MAX:           1535 [pixels]
Y_MAX:           1399 [pixels]
DET_THRESH:      16
PHOTO_THRESH:    9
SL_URL:          sw01036227000msufc0094.fits
SUN_POSTN:       348.89d {+23h 15m 33s}   -4.78d {-04d 46' 30"}
SUN_DIST:         83.91 [deg]   Sun_angle= -5.2 [hr] (East of Sun)
MOON_POSTN:      287.66d {+19h 10m 38s}  -25.05d {-25d 03' 12"}
MOON_DIST:       143.79 [deg]
MOON_ILLUM:      26 [%]
GAL_COORDS:      163.52, -7.81 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       71.31, 15.45 [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 08 Mar 21 06:44:11 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1036227,   Seg_Num: 0
POINT_RA:         67.108d {+04h 28m 26s} (J2000)
POINT_DEC:       +37.420d {+37d 25' 11"} (J2000)
ROLL:            258.999d
IMG_START_DATE:  19281 TJD;    67 DOY;   21/03/08
IMG_START_TIME:  23971.41 SOD {06:39:31.41} UT,   94.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     636878398
X_OFFSET:        1006 [pixels]
Y_OFFSET:        900 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1166
Y_GRB_POS:       1060
BINNING_INDEX:   1
IM_URL:          sw01036227000msuni0121.fits
SUN_POSTN:       348.89d {+23h 15m 33s}   -4.77d {-04d 46' 29"}
SUN_DIST:         83.91 [deg]   Sun_angle= -5.2 [hr] (East of Sun)
MOON_POSTN:      287.67d {+19h 10m 42s}  -25.05d {-25d 03' 10"}
MOON_DIST:       143.77 [deg]
MOON_ILLUM:      26 [%]
GAL_COORDS:      163.52, -7.81 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       71.31, 15.45 [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:     Mon 08 Mar 21 06:44:17 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1036227,   Seg_Num: 0
POINT_RA:         67.108d {+04h 28m 26s} (J2000)
POINT_DEC:       +37.420d {+37d 25' 11"} (J2000)
ROLL:            258.999d
IMG_START_DATE:  19281 TJD;    67 DOY;   21/03/08
IMG_START_TIME:  23971.41 SOD {06:39:31.41} UT,   94.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     636878398
X_OFFSET:        1006 [pixels]
Y_OFFSET:        900 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1166
Y_GRB_POS:       1060
BINNING_INDEX:   1
IM_URL:          sw01036227000msuni0121.fits
SUN_POSTN:       348.89d {+23h 15m 33s}   -4.77d {-04d 46' 29"}
SUN_DIST:         83.91 [deg]   Sun_angle= -5.2 [hr] (East of Sun)
MOON_POSTN:      287.67d {+19h 10m 42s}  -25.05d {-25d 03' 10"}
MOON_DIST:       143.77 [deg]
MOON_ILLUM:      26 [%]
GAL_COORDS:      163.52, -7.81 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       71.31, 15.45 [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:     Mon 08 Mar 21 06:45:10 UT
NOTICE_TYPE:     Swift-UVOT Position
TRIGGER_NUM:     1036227,   Seg_Num: 0
GRB_RA:           67.0738d {+04h 28m 17.71s} (J2000),
                  67.4285d {+04h 29m 42.84s} (current),
                  66.2380d {+04h 24m 57.11s} (1950)
GRB_DEC:         +37.4338d {+37d 26' 01.6"} (J2000),
                 +37.4794d {+37d 28' 45.8"} (current),
                 +37.3235d {+37d 19' 24.5"} (1950)
GRB_ERROR:       0.6 [arcsec radius, statistical only]
GRB_MAG:         18.56 +/- 0.14 [mag]
FILTER:          10, White
IMG_START_DATE:  19281 TJD;    67 DOY;   21/03/08
IMG_START_TIME:  23968.00 SOD {06:39:28.00} UT,   91.2 [sec] since BAT Trigger Time
SUN_POSTN:       348.89d {+23h 15m 33s}   -4.77d {-04d 46' 28"}
SUN_DIST:         83.89 [deg]   Sun_angle= -5.2 [hr] (East of Sun)
MOON_POSTN:      287.68d {+19h 10m 44s}  -25.05d {-25d 03' 09"}
MOON_DIST:       143.74 [deg]
MOON_ILLUM:      26 [%]
GAL_COORDS:      163.49, -7.82 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       71.28, 15.47 [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 8.3 arcsec from the XRT position.  
COMMENTS:        Result based on Genie data.  
COMMENTS:        Notice generated automatically.

GCN Circular #29619
V. D'Elia (SSDC), E. Ambrosi (INAF-IASFPA), S. D. Barthelmy (GSFC), A. D'Ai (INAF-IASFPA), N. J. Klingler (PSU), A. Y. Lien (GSFC/UMBC), K. L. Page (U Leicester), T. Sakamoto (AGU), M. H. Siegel (PSU) and A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift Observatory Team:
At 06:37:56 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 210308A (trigger=1036227). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 67.088, +37.411 which is
```
   RA(J2000)  =  04h 28m 21s
   Dec(J2000) = +37d 24' 39"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a few overlapping peaks with a duration of about 15 sec. The peak count rate was ~6000 counts/sec (15-350 keV), at ~3 sec after the trigger.
The XRT began observing the field at 06:39:21.81 UT, 85.0 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with a position: RA, Dec 67.076417, 37.435310 which is equivalent to:
```
   RA(J2000)  = 04h 28m 18.34s
   Dec(J2000) = +37d 26' 07.11"
```
with an uncertainty of 4.3 arcseconds (radius, 90% containment). This location is 94 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 http://www.swift.ac.uk/sper.
UVOT took a finding chart exposure of 150 seconds with the White filter starting 94 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at
```
  RA(J2000)  =  04:28:17.73 =  67.07388
  DEC(J2000) = +37:26:02.0  =  37.43388
```
with a 90%-confidence error radius of about 0.63 arc sec. This position is 8.5 arc sec. from the center of the XRT error circle. The estimated magnitude is 18.57 with a 1-sigma error of about 0.15. No correction has been made for the expected extinction corresponding to E(B-V) of 1.295.
Burst Advocate for this burst is V. D'Elia (valerio.delia AT ssdc.asi.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:     Mon 08 Mar 21 06:51:13 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1036227,   Seg_Num: 0
POINT_RA:         67.110d {+04h 28m 26s} (J2000)
POINT_DEC:       +37.422d {+37d 25' 21"} (J2000)
POINT_ROLL:      259.002d
IMG_START_DATE:  19281 TJD;    67 DOY;   21/03/08
IMG_START_TIME:  24183.84 SOD {06:43:03.84} UT,   307.0 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.981
N_STARS:         14
X_OFFSET:        686 [pixels]
Y_OFFSET:        580 [pixels]
X_MAX:           1645 [pixels]
Y_MAX:           1539 [pixels]
DET_THRESH:      9
PHOTO_THRESH:    4
SL_URL:          sw01036227000msufc0306.fits
SUN_POSTN:       348.89d {+23h 15m 34s}   -4.77d {-04d 46' 22"}
SUN_DIST:         83.91 [deg]   Sun_angle= -5.2 [hr] (East of Sun)
MOON_POSTN:      287.75d {+19h 10m 59s}  -25.05d {-25d 03' 00"}
MOON_DIST:       143.72 [deg]
MOON_ILLUM:      26 [%]
GAL_COORDS:      163.52, -7.81 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       71.31, 15.46 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 08 Mar 21 06:51:28 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1036227,   Seg_Num: 0
POINT_RA:         67.110d {+04h 28m 26s} (J2000)
POINT_DEC:       +37.422d {+37d 25' 21"} (J2000)
POINT_ROLL:      259.002d
IMG_START_DATE:  19281 TJD;    67 DOY;   21/03/08
IMG_START_TIME:  24183.84 SOD {06:43:03.84} UT,   307.0 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.981
N_STARS:         14
X_OFFSET:        686 [pixels]
Y_OFFSET:        580 [pixels]
X_MAX:           1645 [pixels]
Y_MAX:           1539 [pixels]
DET_THRESH:      9
PHOTO_THRESH:    4
SL_URL:          sw01036227000msufc0306.fits
SUN_POSTN:       348.89d {+23h 15m 34s}   -4.77d {-04d 46' 22"}
SUN_DIST:         83.91 [deg]   Sun_angle= -5.2 [hr] (East of Sun)
MOON_POSTN:      287.75d {+19h 11m 00s}  -25.05d {-25d 03' 00"}
MOON_DIST:       143.72 [deg]
MOON_ILLUM:      26 [%]
GAL_COORDS:      163.52, -7.81 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       71.31, 15.46 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        If you have elected to receive attachments:  
COMMENTS:        The uvot_catalog_srclist.fits.gz file does not exist; skipping the attachment.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 08 Mar 21 06:52:33 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1036227,   Seg_Num: 0
POINT_RA:         67.110d {+04h 28m 26s} (J2000)
POINT_DEC:       +37.422d {+37d 25' 21"} (J2000)
ROLL:            259.002d
IMG_START_DATE:  19281 TJD;    67 DOY;   21/03/08
IMG_START_TIME:  24183.84 SOD {06:43:03.84} UT,   307.0 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     636878610
X_OFFSET:        1006 [pixels]
Y_OFFSET:        900 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1166
Y_GRB_POS:       1060
BINNING_INDEX:   1
IM_URL:          sw01036227000msuni0333.fits
SUN_POSTN:       348.89d {+23h 15m 34s}   -4.77d {-04d 46' 21"}
SUN_DIST:         83.91 [deg]   Sun_angle= -5.2 [hr] (East of Sun)
MOON_POSTN:      287.76d {+19h 11m 02s}  -25.05d {-25d 02' 58"}
MOON_DIST:       143.71 [deg]
MOON_ILLUM:      26 [%]
GAL_COORDS:      163.52, -7.81 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       71.31, 15.46 [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:     Mon 08 Mar 21 06:52:47 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1036227,   Seg_Num: 0
POINT_RA:         67.110d {+04h 28m 26s} (J2000)
POINT_DEC:       +37.422d {+37d 25' 21"} (J2000)
ROLL:            259.002d
IMG_START_DATE:  19281 TJD;    67 DOY;   21/03/08
IMG_START_TIME:  24183.84 SOD {06:43:03.84} UT,   307.0 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     636878610
X_OFFSET:        1006 [pixels]
Y_OFFSET:        900 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1166
Y_GRB_POS:       1060
BINNING_INDEX:   1
IM_URL:          sw01036227000msuni0333.fits
SUN_POSTN:       348.89d {+23h 15m 35s}   -4.77d {-04d 46' 20"}
SUN_DIST:         83.91 [deg]   Sun_angle= -5.2 [hr] (East of Sun)
MOON_POSTN:      287.76d {+19h 11m 03s}  -25.05d {-25d 02' 57"}
MOON_DIST:       143.70 [deg]
MOON_ILLUM:      26 [%]
GAL_COORDS:      163.52, -7.81 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       71.31, 15.46 [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:        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 08 Mar 21 06:58:10 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1036227,   Seg_Num: 0
POINT_RA:         67.110d {+04h 28m 26s} (J2000)
POINT_DEC:       +37.422d {+37d 25' 21"} (J2000)
POINT_ROLL:      259.001d
IMG_START_DATE:  19281 TJD;    67 DOY;   21/03/08
IMG_START_TIME:  24736.38 SOD {06:52:16.38} UT,   859.5 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.846
N_STARS:         157
X_OFFSET:        446 [pixels]
Y_OFFSET:        340 [pixels]
X_MAX:           1885 [pixels]
Y_MAX:           1779 [pixels]
DET_THRESH:      16
PHOTO_THRESH:    9
SL_URL:          sw01036227000msufc0859.fits
SUN_POSTN:       348.90d {+23h 15m 35s}   -4.77d {-04d 46' 15"}
SUN_DIST:         83.90 [deg]   Sun_angle= -5.2 [hr] (East of Sun)
MOON_POSTN:      287.82d {+19h 11m 16s}  -25.05d {-25d 02' 49"}
MOON_DIST:       143.66 [deg]
MOON_ILLUM:      26 [%]
GAL_COORDS:      163.52, -7.81 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       71.31, 15.46 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 08 Mar 21 06:58:23 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1036227,   Seg_Num: 0
POINT_RA:         67.110d {+04h 28m 26s} (J2000)
POINT_DEC:       +37.422d {+37d 25' 21"} (J2000)
POINT_ROLL:      259.001d
IMG_START_DATE:  19281 TJD;    67 DOY;   21/03/08
IMG_START_TIME:  24736.38 SOD {06:52:16.38} UT,   859.5 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.846
N_STARS:         157
X_OFFSET:        446 [pixels]
Y_OFFSET:        340 [pixels]
X_MAX:           1885 [pixels]
Y_MAX:           1779 [pixels]
DET_THRESH:      16
PHOTO_THRESH:    9
SL_URL:          sw01036227000msufc0859.fits
SUN_POSTN:       348.90d {+23h 15m 35s}   -4.77d {-04d 46' 15"}
SUN_DIST:         83.90 [deg]   Sun_angle= -5.2 [hr] (East of Sun)
MOON_POSTN:      287.82d {+19h 11m 17s}  -25.05d {-25d 02' 49"}
MOON_DIST:       143.66 [deg]
MOON_ILLUM:      26 [%]
GAL_COORDS:      163.52, -7.81 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       71.31, 15.46 [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 08 Mar 21 06:59:34 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1036227,   Seg_Num: 0
POINT_RA:         67.110d {+04h 28m 26s} (J2000)
POINT_DEC:       +37.422d {+37d 25' 21"} (J2000)
ROLL:            259.001d
IMG_START_DATE:  19281 TJD;    67 DOY;   21/03/08
IMG_START_TIME:  24736.38 SOD {06:52:16.38} UT,   859.5 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     636879163
X_OFFSET:        1005 [pixels]
Y_OFFSET:        899 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1165
Y_GRB_POS:       1059
BINNING_INDEX:   1
IM_URL:          sw01036227000msuni0886.fits
SUN_POSTN:       348.90d {+23h 15m 36s}   -4.77d {-04d 46' 14"}
SUN_DIST:         83.90 [deg]   Sun_angle= -5.2 [hr] (East of Sun)
MOON_POSTN:      287.83d {+19h 11m 20s}  -25.05d {-25d 02' 47"}
MOON_DIST:       143.65 [deg]
MOON_ILLUM:      26 [%]
GAL_COORDS:      163.52, -7.81 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       71.31, 15.46 [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 08 Mar 21 06:59:42 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1036227,   Seg_Num: 0
POINT_RA:         67.110d {+04h 28m 26s} (J2000)
POINT_DEC:       +37.422d {+37d 25' 21"} (J2000)
ROLL:            259.001d
IMG_START_DATE:  19281 TJD;    67 DOY;   21/03/08
IMG_START_TIME:  24736.38 SOD {06:52:16.38} UT,   859.5 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     636879163
X_OFFSET:        1005 [pixels]
Y_OFFSET:        899 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1165
Y_GRB_POS:       1059
BINNING_INDEX:   1
IM_URL:          sw01036227000msuni0886.fits
SUN_POSTN:       348.90d {+23h 15m 36s}   -4.77d {-04d 46' 14"}
SUN_DIST:         83.90 [deg]   Sun_angle= -5.2 [hr] (East of Sun)
MOON_POSTN:      287.83d {+19h 11m 20s}  -25.05d {-25d 02' 47"}
MOON_DIST:       143.65 [deg]
MOON_ILLUM:      26 [%]
GAL_COORDS:      163.52, -7.81 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       71.31, 15.46 [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 #29621
S. Ogata, R. Hosokawa, K. L. Murata, R. Adachi, M. Niwano, F. Ogawa, N. Nakamura, N. Ito, H. Takamatsu, H. Hara, Y. Yatsu, and N. Kawai (TokyoTech) report on behalf of the MITSuME collaboration:
We observed the field of GRB 210308A (D'Elia et al.,GCN Circular #29619) with the optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope of Okayama Astrophysical Observatory, Okayama, Japan. The observation with a series of 60 sec exposures started at 2021-03-08 11:03:59 UT.(4.5 hours after Swift BAT trigger) We stacked the images with good conditions. We did not detect the optical afterglow reported previously (D'Elia et al.,GCN Circular #29619) in all three bands. We obtained the 5-sigma limits of the stacked images as follows.
```
T0+[hour] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
4.5 11:51:53 4440 g'>17.6, Rc>17.8, Ic>17.8
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
```
We used the PS1 catalog for flux calibration. The magnitudes are expressed in the AB system. The images were processed in real-time through the MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ, Vol.73, Issue 1, Pages 4-24; https://github.com/MNiwano/Eclaire).
GCN Circular #29623
Z.P. Zhu (NAOC, HUST), S.Y. Fu, X. Liu, D. Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:
We observed the field of GRB 210308A (D'Elia et al., GCN 29619) using the NEXT-0.6m optical telescope located at Nanshan, Xinjiang, China. Observations started at 14:16:29 UT on 2021-03-08, i.e., 7.67 hr after the BAT trigger. We obtained 15x200 s frames in the Sloan r- and i- bands, respectively.
The optical afterglow (D'Elia et al., GCN 29619) of the burst is not detected in our stacked images, down to limiting magnitudes of r ~ 21.7 and i ~ 21.3, calibrated with nearby PS1 stars.
GCN Circular #29626
S. Lesage (UAH), A. von Kienlin (MPE), C. Meegan (UAH), and C. Malacaria (NASA-MSFC/USRA) report on behalf of the Fermi GBM Team:
"At 06:37:56.91 UT on 08 March 2021, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 210308A (trigger 636878281 / 210308276) which was also detected by the Swift/BAT and Swift/XRT (D'Elia et al. 2021, GCN 29619). The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 26 degrees.
The GBM light curve shows a single-peaked structure with a duration (T90) of about 5.4 s (50-300 keV). The time-averaged spectrum from T0-1.7 s to T0+7.5 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.82 +/- 0.04 and the cutoff energy, parameterized as Epeak, is 142 +/- 5 keV. A Band function fits the spectrum equally well with Epeak = 135 +/- 7 keV, alpha = -0.78 +/- 0.05 and beta = -3.0 +/- 0.4.
The event fluence (10-1000 keV) in this time interval is (6.3 +/- 0.1)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+2.1 s in the 10-1000 keV band is 20.0 +/- 0.4 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html
For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"
GCN Circular #29627
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-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 GRB 210308A ( V. D'Elia et al., GCN 29619) errorbox 40899 sec after notice time and 40918 sec after trigger time at 2021-03-08 17:59:54 UT, with upper limit up to 13.9 mag. Observations started at twilight. The observations began at zenith distance = 74 deg. The sun altitude is -12.2 deg.
MASTER-IAC robotic telescope located in Spain (IAC Teide Observatory) was pointed to the Swift GRB 210308A errorbox 55958 sec after notice time and 55976 sec after trigger time at 2021-03-08 22:10:53 UT, with upper limit up to 18.5 mag. The observations began at zenith distance = 48 deg. The sun altitude is -40.8 deg.
The galactic latitude b = -7 deg., longitude l = 164 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1563625
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

   21950 |             MASTER- |   C |    60 | 18.0 |        
   22210 |             MASTER- |   C |    60 | 15.8 |        
   22945 |             MASTER- |   C |    60 | 12.6 |        
   41008 |         MASTER-SAAO |   C |   180 | 13.9 |        
   56067 |          MASTER-IAC |   C |   180 | 18.5 |        
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
GCN Circular #29630
GRB 210308A: Swift/UVOT Detection
J. D. Gropp (PSU) and V. D'Elia (SSDC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 210308A 95 s after the BAT trigger (D'Elia et al., GCN Circ. 29619). A source consistent with the XRT position (D'Elia et al., GCN Circ. 29619) is detected in the initial UVOT exposures.
The preliminary UVOT position is:
```
    RA  (J2000) =  04:28:17.73 =  67.07389 (deg.)
    Dec (J2000) = +37:26:02.1  =  37.43391 (deg.)
```
with an estimated uncertainty of 0.46 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

b                   765        1189            38        >18.62
uvm2                864        1115            38        >17.52
u                   338        1164           284        >19.50
v                   667        1090            58        >17.84
uvw1               1120        1140            19        >17.25
uvw2                815        1231            50        >17.91
white               126         275           292    18.54+-0.07
white               618        1213           205        >20.20
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 1.296 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #29633
D. M. Palmer (LANL), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), V. D'Elia (SSDC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-60 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 210308A (trigger #1036227) (D'Elia, et al., GCN Circ. 29619). The BAT ground-calculated position is RA, Dec = 67.083, 37.429 deg which is
```
    RA(J2000)  =  04h 28m 19.9s
    Dec(J2000) = +37d 25' 42.9"
```
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 32%.
The mask-weighted light curve shows a double-peaked structure from T-0.5 sec to T+9 sec. The first pulse peaks at T+0.2 sec, and the second pulse peaks at T+3 sec. T90 (15-350 keV) is 5.3 +- 0.6 sec (estimated error including systematics).
The time-averaged spectrum from T-0.04 to T+7.36 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.76 +- 0.28, and Epeak of 113.6 +- 31.0 keV (chi squared 52.89 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 3.2 +- 0.1 x 10^-6 erg/cm2 and the 1-sec peak flux measured from T+2.12 sec in the 15-150 keV band is 13.6 +- 0.7 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.38 +- 0.06 (chi squared 69.63 for 57 d.o.f.). 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/1036227/BA/
GCN Circular #29634
S. Belkin (IKI), N. Pankov (HSE), A. Pozanenko (IKI), E. Klunko (ISTP), R. Ya. Inasaridze (AbAO), V. R. Ayvazian (AbAO), G. V. Kapanadze (AbAO), D. G. Datashvili (AbAO) report on behalf of IKI-GRB-FuN:
We observed the field of GRB 210308A (D'Elia et al., GCN 29619) with AZT-33IK telescope of Sayan observatory (Mondy) starting on 2021-03-08 (UT) 13:00:45 and AS-32 telescope of Abastumani observatory (AbAO) starting on 2021-03-08 (UT) 16:32:07 (both in R-filter). The optical afterglow (D'Elia et al., GCN 29619; Gropp et al., GCN 29630; see also Ogata et al., GCN 29621; Zhu et al., GCN 29623; Lipunov et al., GCN 29627) is detected in stacked image of AZT-33IK and not detected at AS-32.
```
Date       UT start   t-T0    Filter  Exp.   OT    Err.  UL(3sigma)
                        (mid, days)     (s)

2021-03-08 13:00:45   0.27626  R      15*120 22.77  0.27 22.8 AZT-33IK
2021-03-08 16:32:07   0.42131  R      25*60  n/d    n/d  21.8 AS-32
```
The photometry is based on nearby USNO-B1.0 stars
```
USNO-B1.0_id R2
1274-0090800 15.34
1274-0090824 17.35
```
GCN Circular #29643
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 210308A (Swift-BAT detection: D'Elia et al., GCN Circ. 29619, Palmer et al., GCN Circ. 29633; Fermi-GBM detection: Lesage et al., GCN Circ. 29626) triggered Konus-Wind at T0=23879.936 s UT (06:37:59.936).
The burst light curve shows a multi-peaked structure which starts at ~T0-3.8 s and has a total duration of ~8.9 s. The emission is seen up to ~1 MeV.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB210308_T23879/
As observed by Konus-Wind, the burst had a fluence of 5.00(-0.48,+0.53)x10^-6 erg/cm2, and a 64-ms peak flux, measured from T0+1.264 s, of 3.36(-0.85,+0.87)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst (measured from T0 to T0+8.448 s) is best fit in the 20 keV - 1 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.73(-0.32,+0.38) and Ep = 150(-19,+25) keV (chi2 = 49/55 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.7 (chi2 = 49/54 dof).
All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.

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