Gamma-ray Burst 210318A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 18 Mar 21 03:55:17 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1037339,   Seg_Num: 0
GRB_RA:           33.930d {+02h 15m 43s} (J2000),
                  34.151d {+02h 16m 36s} (current),
                  33.410d {+02h 13m 38s} (1950)
GRB_DEC:         -37.789d {-37d 47' 21"} (J2000),
                 -37.692d {-37d 41' 29"} (current),
                 -38.021d {-38d 01' 15"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       7325 [cnts]    Image_Peak=242 [image_cnts]
TRIGGER_DUR:     3.072 [sec] 
TRIGGER_INDEX:   474     E_range: 25-100 keV
BKG_INTEN:       65114 [cnts]
BKG_TIME:        14029.31 SOD {03:53:49.31} UT
BKG_DUR:         32 [sec]
GRB_DATE:        19291 TJD;    77 DOY;   21/03/18
GRB_TIME:        14071.68 SOD {03:54:31.68} UT
GRB_PHI:         -152.43 [deg]
GRB_THETA:        30.47 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     11.26 [sigma]
IMAGE_SIGNIF:    7.72 [sigma]
MERIT_PARAMS:     +1  +0  +0  +2  +2  -2  +0  +0 -64  +0 
SUN_POSTN:       357.96d {+23h 51m 51s}   -0.88d {-00d 53' 00"}
SUN_DIST:         49.61 [deg]   Sun_angle= -2.4 [hr] (East of Sun)
MOON_POSTN:       48.31d {+03h 13m 15s}  +15.91d {+15d 54' 37"}
MOON_DIST:        55.23 [deg]
MOON_ILLUM:      20 [%]
GAL_COORDS:      249.28,-69.34 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       13.79,-47.53 [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 = 181.38,11.18 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 18 Mar 21 03:56:40 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     1037339,   Seg_Num: 0
POINT_RA:         33.973d {+02h 15m 53s} (J2000)
POINT_DEC:       -37.808d {-37d 48' 28"} (J2000)
IMG_START_DATE:  19291 TJD;    77 DOY;   21/03/18
IMG_START_TIME:  14195.23 SOD {03:56:35.23} UT,   123.5 [sec] since BAT Trigger Time
COUNTS:          7    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        1    Max_iter_allowed= 4
ERROR_CODE:      1
COMMENTS:        SWIFT-XRT Nack Position.  
COMMENTS:        No source found in the image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 18 Mar 21 03:58:20 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1037339,   Seg_Num: 0
GRB_RA:           33.930d {+02h 15m 43s} (J2000),
                  34.151d {+02h 16m 36s} (current),
                  33.410d {+02h 13m 38s} (1950)
GRB_DEC:         -37.789d {-37d 47' 21"} (J2000),
                 -37.692d {-37d 41' 29"} (current),
                 -38.021d {-38d 01' 15"} (1950)
GRB_DATE:        19291 TJD;    77 DOY;   21/03/18
GRB_TIME:        14071.68 SOD {03:54:31.68} UT
TRIGGER_INDEX:   474
GRB_PHI:         -152.43 [deg]
GRB_THETA:        30.47 [deg]
DELTA_TIME:      -76.00 [sec]
TRIGGER_DUR:     3.072 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     11.26 [sigma]
IMAGE_SIGNIF:    7.72 [sigma]
LC_URL:          sw01037339000msb.lc
SUN_POSTN:       357.96d {+23h 51m 51s}   -0.88d {-00d 52' 57"}
SUN_DIST:         49.61 [deg]   Sun_angle= -2.4 [hr] (East of Sun)
MOON_POSTN:       48.34d {+03h 13m 21s}  +15.92d {+15d 55' 08"}
MOON_DIST:        55.25 [deg]
MOON_ILLUM:      20 [%]
GAL_COORDS:      249.28,-69.34 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       13.79,-47.53 [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 = 181.38,11.18 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 18 Mar 21 03:59:37 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1037339,   Seg_Num: 0
POINT_RA:         33.973d {+02h 15m 54s} (J2000)
POINT_DEC:       -37.807d {-37d 48' 26"} (J2000)
POINT_ROLL:      309.438d
IMG_START_DATE:  19291 TJD;    77 DOY;   21/03/18
IMG_START_TIME:  14198.50 SOD {03:56:38.50} UT,   126.8 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.958
N_STARS:         12
X_OFFSET:        684 [pixels]
Y_OFFSET:        369 [pixels]
X_MAX:           1643 [pixels]
Y_MAX:           1328 [pixels]
DET_THRESH:      17
PHOTO_THRESH:    9
SL_URL:          sw01037339000msufc0126.fits
SUN_POSTN:       357.96d {+23h 51m 51s}   -0.88d {-00d 52' 56"}
SUN_DIST:         49.65 [deg]   Sun_angle= -2.4 [hr] (East of Sun)
MOON_POSTN:       48.35d {+03h 13m 24s}  +15.92d {+15d 55' 21"}
MOON_DIST:        55.26 [deg]
MOON_ILLUM:      20 [%]
GAL_COORDS:      249.29,-69.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       13.82,-47.56 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 18 Mar 21 03:59:54 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1037339,   Seg_Num: 0
POINT_RA:         33.973d {+02h 15m 54s} (J2000)
POINT_DEC:       -37.807d {-37d 48' 26"} (J2000)
POINT_ROLL:      309.438d
IMG_START_DATE:  19291 TJD;    77 DOY;   21/03/18
IMG_START_TIME:  14198.50 SOD {03:56:38.50} UT,   126.8 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.958
N_STARS:         12
X_OFFSET:        684 [pixels]
Y_OFFSET:        369 [pixels]
X_MAX:           1643 [pixels]
Y_MAX:           1328 [pixels]
DET_THRESH:      17
PHOTO_THRESH:    9
SL_URL:          sw01037339000msufc0126.fits
SUN_POSTN:       357.96d {+23h 51m 51s}   -0.88d {-00d 52' 55"}
SUN_DIST:         49.65 [deg]   Sun_angle= -2.4 [hr] (East of Sun)
MOON_POSTN:       48.35d {+03h 13m 24s}  +15.92d {+15d 55' 24"}
MOON_DIST:        55.26 [deg]
MOON_ILLUM:      20 [%]
GAL_COORDS:      249.29,-69.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       13.82,-47.56 [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:     Thu 18 Mar 21 04:01:01 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1037339,   Seg_Num: 0
POINT_RA:         33.973d {+02h 15m 54s} (J2000)
POINT_DEC:       -37.807d {-37d 48' 26"} (J2000)
ROLL:            309.438d
IMG_START_DATE:  19291 TJD;    77 DOY;   21/03/18
IMG_START_TIME:  14198.50 SOD {03:56:38.50} UT,   126.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     637732625
X_OFFSET:        1003 [pixels]
Y_OFFSET:        688 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1163
Y_GRB_POS:       848
BINNING_INDEX:   1
IM_URL:          sw01037339000msuni0153.fits
SUN_POSTN:       357.96d {+23h 51m 51s}   -0.88d {-00d 52' 54"}
SUN_DIST:         49.65 [deg]   Sun_angle= -2.4 [hr] (East of Sun)
MOON_POSTN:       48.36d {+03h 13m 26s}  +15.93d {+15d 55' 35"}
MOON_DIST:        55.27 [deg]
MOON_ILLUM:      20 [%]
GAL_COORDS:      249.29,-69.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       13.82,-47.56 [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:     Thu 18 Mar 21 04:01:11 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1037339,   Seg_Num: 0
POINT_RA:         33.973d {+02h 15m 54s} (J2000)
POINT_DEC:       -37.807d {-37d 48' 26"} (J2000)
ROLL:            309.438d
IMG_START_DATE:  19291 TJD;    77 DOY;   21/03/18
IMG_START_TIME:  14198.50 SOD {03:56:38.50} UT,   126.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     637732625
X_OFFSET:        1003 [pixels]
Y_OFFSET:        688 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1163
Y_GRB_POS:       848
BINNING_INDEX:   1
IM_URL:          sw01037339000msuni0153.fits
SUN_POSTN:       357.96d {+23h 51m 51s}   -0.88d {-00d 52' 54"}
SUN_DIST:         49.65 [deg]   Sun_angle= -2.4 [hr] (East of Sun)
MOON_POSTN:       48.36d {+03h 13m 27s}  +15.93d {+15d 55' 37"}
MOON_DIST:        55.27 [deg]
MOON_ILLUM:      20 [%]
GAL_COORDS:      249.29,-69.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       13.82,-47.56 [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:     Thu 18 Mar 21 04:00:26 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     1037339,   Seg_Num: 0
GRB_RA:           33.9263d {+02h 15m 42.31s} (J2000),
                  34.1469d {+02h 16m 35.26s} (current),
                  33.4059d {+02h 13m 37.41s} (1950)
GRB_DEC:         -37.7782d {-37d 46' 41.5"} (J2000),
                 -37.6804d {-37d 40' 49.2"} (current),
                 -38.0099d {-38d 00' 35.6"} (1950)
GRB_ERROR:       4.7 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  19291 TJD;    77 DOY;   21/03/18
IMG_START_TIME:  14206.00 SOD {03:56:46.00} UT,   134.3 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       357.96d {+23h 51m 51s}   -0.88d {-00d 52' 55"}
SUN_DIST:         49.60 [deg]   Sun_angle= -2.4 [hr] (East of Sun)
MOON_POSTN:       48.36d {+03h 13m 25s}  +15.92d {+15d 55' 29"}
MOON_DIST:        55.25 [deg]
MOON_ILLUM:      20 [%]
GAL_COORDS:      249.26,-69.35 [deg] galactic lon,lat of the burst
ECL_COORDS:       13.80,-47.52 [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:     Thu 18 Mar 21 04:07:28 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1037339,   Seg_Num: 0
POINT_RA:         33.974d {+02h 15m 54s} (J2000)
POINT_DEC:       -37.807d {-37d 48' 23"} (J2000)
POINT_ROLL:      309.436d
IMG_START_DATE:  19291 TJD;    77 DOY;   21/03/18
IMG_START_TIME:  14356.47 SOD {03:59:16.47} UT,   284.8 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.895
N_STARS:         80
X_OFFSET:        444 [pixels]
Y_OFFSET:        129 [pixels]
X_MAX:           1883 [pixels]
Y_MAX:           1568 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    4
SL_URL:          sw01037339000msufc0284.fits
SUN_POSTN:       357.97d {+23h 51m 52s}   -0.88d {-00d 52' 48"}
SUN_DIST:         49.65 [deg]   Sun_angle= -2.4 [hr] (East of Sun)
MOON_POSTN:       48.41d {+03h 13m 39s}  +15.94d {+15d 56' 40"}
MOON_DIST:        55.29 [deg]
MOON_ILLUM:      20 [%]
GAL_COORDS:      249.29,-69.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       13.83,-47.56 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 18 Mar 21 04:07:36 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1037339,   Seg_Num: 0
POINT_RA:         33.974d {+02h 15m 54s} (J2000)
POINT_DEC:       -37.807d {-37d 48' 23"} (J2000)
POINT_ROLL:      309.436d
IMG_START_DATE:  19291 TJD;    77 DOY;   21/03/18
IMG_START_TIME:  14356.47 SOD {03:59:16.47} UT,   284.8 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.895
N_STARS:         80
X_OFFSET:        444 [pixels]
Y_OFFSET:        129 [pixels]
X_MAX:           1883 [pixels]
Y_MAX:           1568 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    4
SL_URL:          sw01037339000msufc0284.fits
SUN_POSTN:       357.97d {+23h 51m 52s}   -0.88d {-00d 52' 48"}
SUN_DIST:         49.65 [deg]   Sun_angle= -2.4 [hr] (East of Sun)
MOON_POSTN:       48.41d {+03h 13m 39s}  +15.94d {+15d 56' 41"}
MOON_DIST:        55.29 [deg]
MOON_ILLUM:      20 [%]
GAL_COORDS:      249.29,-69.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       13.83,-47.56 [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:     Thu 18 Mar 21 04:07:46 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     1037339,   Seg_Num: 0
GRB_RA:           33.9262d {+02h 15m 42.28s} (J2000),
                  34.1468d {+02h 16m 35.23s} (current),
                  33.4058d {+02h 13m 37.39s} (1950)
GRB_DEC:         -37.7772d {-37d 46' 37.9"} (J2000),
                 -37.6794d {-37d 40' 45.6"} (current),
                 -38.0089d {-38d 00' 32.0"} (1950)
GRB_ERROR:       3.2 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  19291 TJD;    77 DOY;   21/03/18
IMG_START_TIME:  14206.00 SOD {03:56:46.00} UT,   134.3 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       357.97d {+23h 51m 52s}   -0.88d {-00d 52' 48"}
SUN_DIST:         49.60 [deg]   Sun_angle= -2.4 [hr] (East of Sun)
MOON_POSTN:       48.41d {+03h 13m 39s}  +15.95d {+15d 56' 43"}
MOON_DIST:        55.28 [deg]
MOON_ILLUM:      20 [%]
GAL_COORDS:      249.26,-69.35 [deg] galactic lon,lat of the burst
ECL_COORDS:       13.80,-47.52 [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:     Thu 18 Mar 21 04:08:51 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1037339,   Seg_Num: 0
POINT_RA:         33.974d {+02h 15m 54s} (J2000)
POINT_DEC:       -37.807d {-37d 48' 23"} (J2000)
ROLL:            309.436d
IMG_START_DATE:  19291 TJD;    77 DOY;   21/03/18
IMG_START_TIME:  14356.47 SOD {03:59:16.47} UT,   284.8 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     637732783
X_OFFSET:        1003 [pixels]
Y_OFFSET:        688 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1163
Y_GRB_POS:       848
BINNING_INDEX:   1
IM_URL:          sw01037339000msuni0311.fits
SUN_POSTN:       357.97d {+23h 51m 53s}   -0.88d {-00d 52' 47"}
SUN_DIST:         49.65 [deg]   Sun_angle= -2.4 [hr] (East of Sun)
MOON_POSTN:       48.42d {+03h 13m 41s}  +15.95d {+15d 56' 54"}
MOON_DIST:        55.30 [deg]
MOON_ILLUM:      20 [%]
GAL_COORDS:      249.29,-69.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       13.83,-47.56 [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:     Thu 18 Mar 21 04:09:04 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1037339,   Seg_Num: 0
POINT_RA:         33.974d {+02h 15m 54s} (J2000)
POINT_DEC:       -37.807d {-37d 48' 23"} (J2000)
ROLL:            309.436d
IMG_START_DATE:  19291 TJD;    77 DOY;   21/03/18
IMG_START_TIME:  14356.47 SOD {03:59:16.47} UT,   284.8 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     637732783
X_OFFSET:        1003 [pixels]
Y_OFFSET:        688 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1163
Y_GRB_POS:       848
BINNING_INDEX:   1
IM_URL:          sw01037339000msuni0311.fits
SUN_POSTN:       357.97d {+23h 51m 53s}   -0.88d {-00d 52' 46"}
SUN_DIST:         49.65 [deg]   Sun_angle= -2.4 [hr] (East of Sun)
MOON_POSTN:       48.42d {+03h 13m 42s}  +15.95d {+15d 56' 56"}
MOON_DIST:        55.30 [deg]
MOON_ILLUM:      20 [%]
GAL_COORDS:      249.29,-69.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       13.83,-47.56 [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 #29662
E. Troja (NASA/GSFC/UMCP), C. Gronwall (PSU), J.D. Gropp (PSU), N. J. Klingler (PSU), H. A. Krimm (NSF), A. Y. Lien (GSFC/UMBC), 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 03:54:31 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 210318A (trigger=1037339). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 33.930, -37.789 which is
```
   RA(J2000) = 02h 15m 43s
   Dec(J2000) = -37d 47' 21"
```
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 ~700 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 03:56:35.2 UT, 123.5 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 33.9263, -37.7772 which is equivalent to:
```
   RA(J2000)  = 02h 15m 42.32s
   Dec(J2000) = -37d 46' 38.1"
```
with an uncertainty of 3.2 arcseconds (radius, 90% containment). This location is 43 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. We cannot determine whether the source is fading at the present time.
A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 1.88 x 10^20 cm^-2 (Willingale et al. 2013).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 126 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 0.016.
Burst Advocate for this burst is E. Troja (eleonora.troja AT nasa.gov). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/)

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 18 Mar 21 04:15:07 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1037339,   Seg_Num: 0
POINT_RA:         33.974d {+02h 15m 54s} (J2000)
POINT_DEC:       -37.807d {-37d 48' 23"} (J2000)
POINT_ROLL:      309.436d
IMG_START_DATE:  19291 TJD;    77 DOY;   21/03/18
IMG_START_TIME:  14935.82 SOD {04:08:55.82} UT,   864.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.468
N_STARS:         103
X_OFFSET:        444 [pixels]
Y_OFFSET:        129 [pixels]
X_MAX:           1883 [pixels]
Y_MAX:           1568 [pixels]
DET_THRESH:      13
PHOTO_THRESH:    7
SL_URL:          sw01037339000msufc0864.fits
SUN_POSTN:       357.97d {+23h 51m 54s}   -0.88d {-00d 52' 40"}
SUN_DIST:         49.64 [deg]   Sun_angle= -2.4 [hr] (East of Sun)
MOON_POSTN:       48.47d {+03h 13m 53s}  +15.97d {+15d 57' 57"}
MOON_DIST:        55.33 [deg]
MOON_ILLUM:      20 [%]
GAL_COORDS:      249.29,-69.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       13.83,-47.56 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 18 Mar 21 04:16:24 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1037339,   Seg_Num: 0
POINT_RA:         33.974d {+02h 15m 54s} (J2000)
POINT_DEC:       -37.807d {-37d 48' 23"} (J2000)
ROLL:            309.436d
IMG_START_DATE:  19291 TJD;    77 DOY;   21/03/18
IMG_START_TIME:  14935.82 SOD {04:08:55.82} UT,   864.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     637733362
X_OFFSET:        1003 [pixels]
Y_OFFSET:        688 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1163
Y_GRB_POS:       848
BINNING_INDEX:   1
IM_URL:          sw01037339000msuni0891.fits
SUN_POSTN:       357.97d {+23h 51m 54s}   -0.88d {-00d 52' 39"}
SUN_DIST:         49.64 [deg]   Sun_angle= -2.4 [hr] (East of Sun)
MOON_POSTN:       48.48d {+03h 13m 56s}  +15.97d {+15d 58' 10"}
MOON_DIST:        55.33 [deg]
MOON_ILLUM:      20 [%]
GAL_COORDS:      249.29,-69.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       13.83,-47.56 [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:     Thu 18 Mar 21 04:15:20 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1037339,   Seg_Num: 0
POINT_RA:         33.974d {+02h 15m 54s} (J2000)
POINT_DEC:       -37.807d {-37d 48' 23"} (J2000)
POINT_ROLL:      309.436d
IMG_START_DATE:  19291 TJD;    77 DOY;   21/03/18
IMG_START_TIME:  14935.82 SOD {04:08:55.82} UT,   864.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.468
N_STARS:         103
X_OFFSET:        444 [pixels]
Y_OFFSET:        129 [pixels]
X_MAX:           1883 [pixels]
Y_MAX:           1568 [pixels]
DET_THRESH:      13
PHOTO_THRESH:    7
SL_URL:          sw01037339000msufc0864.fits
SUN_POSTN:       357.97d {+23h 51m 54s}   -0.88d {-00d 52' 40"}
SUN_DIST:         49.64 [deg]   Sun_angle= -2.4 [hr] (East of Sun)
MOON_POSTN:       48.47d {+03h 13m 54s}  +15.97d {+15d 57' 59"}
MOON_DIST:        55.33 [deg]
MOON_ILLUM:      20 [%]
GAL_COORDS:      249.29,-69.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       13.83,-47.56 [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:     Thu 18 Mar 21 04:16:37 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1037339,   Seg_Num: 0
POINT_RA:         33.974d {+02h 15m 54s} (J2000)
POINT_DEC:       -37.807d {-37d 48' 23"} (J2000)
ROLL:            309.436d
IMG_START_DATE:  19291 TJD;    77 DOY;   21/03/18
IMG_START_TIME:  14935.82 SOD {04:08:55.82} UT,   864.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     637733362
X_OFFSET:        1003 [pixels]
Y_OFFSET:        688 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1163
Y_GRB_POS:       848
BINNING_INDEX:   1
IM_URL:          sw01037339000msuni0891.fits
SUN_POSTN:       357.97d {+23h 51m 54s}   -0.88d {-00d 52' 39"}
SUN_DIST:         49.64 [deg]   Sun_angle= -2.4 [hr] (East of Sun)
MOON_POSTN:       48.48d {+03h 13m 56s}  +15.97d {+15d 58' 12"}
MOON_DIST:        55.34 [deg]
MOON_ILLUM:      20 [%]
GAL_COORDS:      249.29,-69.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       13.83,-47.56 [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 #29665
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 210318A ( E. Troja et al., GCN 29662) errorbox 50452 sec after notice time and 50501 sec after trigger time at 2021-03-18 17:56:12 UT, with upper limit up to 19.7 mag. Observations started at twilight. The observations began at zenith distance = 58 deg. The sun altitude is -14.2 deg.
The galactic latitude b = -69 deg., longitude l = 248 deg.

Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1570922
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

   50591 |         MASTER-SAAO |   C |   180 | 19.7 |        
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
GCN Circular #29670
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team.
Using 1075 s of XRT Photon Counting mode data and 2 UVOT images for GRB 210318A, 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 = 33.92621, -37.77693 which is equivalent to:
```
RA (J2000): 02h 15m 42.29s
Dec (J2000): -37d 46' 36.9"
```
with an uncertainty of 2.4 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 #29671
B. Sbarufatti (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , D.N. Burrows (PSU), J. D. Gropp (PSU) and E. Troja report on behalf of the Swift-XRT team:
We have analysed 3.1 ks of XRT data for GRB 210318A (Troja et al. GCN Circ. 29662), from 107 s to 45.6 ks after the BAT trigger. The data comprise 9 s in Windowed Timing (WT) mode (taken while Swift was slewing), with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN Circ. 29670).
The light curve can be modelled with a power-law decay with a decay index of alpha=1.09 (+0.27, -0.29).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.8 (+0.6, -0.5). The best-fitting absorption column is 1.4 (+1.9, -1.2) x 10^21 cm^-2, consistent with the Galactic value of 1.9 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 3.8 x 10^-11 (4.6 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     1.4 (+1.9, -1.2) x 10^21 cm^-2
Galactic foreground: 1.9 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.8 (+0.6, -0.5)
```
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01037339.
This circular is an official product of the Swift-XRT team.
GCN Circular #29672
T. Sakamoto (AGU), 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), M. Stamatikos (OSU), E. Troja (NASA/GSFC, UMCP), 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 210318A (trigger #1037339) (Troja, et al., GCN Circ. 29662). The BAT ground-calculated position is RA, Dec = 33.892, -37.755 deg which is
```
  RA(J2000)  =  02h 15m 34.0s 
  Dec(J2000) = -37d 45' 17.7" 
```
with an uncertainty of 2.9 arcmin, (radius, sys+stat, 90% containment). The partial coding was 75%.
The mask-weighted light curves shows a single broad FRED-shaped peak with some structure. The emission starts at ~T10 sec, peaks at T+5 sec, and falls to background by T+50 sec. T90 (15-350 keV) is 48.00 +- 22.63 sec (estimated error including systematics).
The time-averaged spectrum from T-12.37 to T+35.63 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.48 +- 0.33. The fluence in the 15-150 keV band is 6.4 +- 1.3 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+11.13 sec in the 15-150 keV band is 0.3 +- 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/1037339/BA/
GCN Circular #29706
M. H. Siegel (PSU) and E. Troja (NASA/GSFC/UMCP) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 210318A 127 s after the BAT trigger (Troja et al., GCN Circ. 29662). No optical afterglow consistent with the XRT position (Troja et al. GCN Circ. 29662) 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           127          277          147         >20.5
u_FC               285          535          246         >19.9
white              127         1188          353         >21.0
v                  614         1064           58         >18.6
b                  541         1163           58         >19.3
u                  285          535          246         >19.9
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.017 in the direction of the burst (Schlegel et al. 1998).

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Jochen Greiner, last update: 24-Mar-2021 [Disclaimer]