Gamma-ray Burst 210517A

(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 17 May 21 05:28:14 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1048783,   Seg_Num: 0
GRB_RA:          358.174d {+23h 52m 42s} (J2000),
                 358.451d {+23h 53m 48s} (current),
                 357.525d {+23h 50m 06s} (1950)
GRB_DEC:         -39.105d {-39d 06' 17"} (J2000),
                 -38.986d {-38d 59' 08"} (current),
                 -39.383d {-39d 22' 58"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       1647 [cnts]    Image_Peak=121 [image_cnts]
TRIGGER_DUR:     0.512 [sec] 
TRIGGER_INDEX:   121     E_range: 15-50 keV
BKG_INTEN:       15747 [cnts]
BKG_TIME:        19668.96 SOD {05:27:48.96} UT
BKG_DUR:         8 [sec]
GRB_DATE:        19351 TJD;   137 DOY;   21/05/17
GRB_TIME:        19681.57 SOD {05:28:01.57} UT
GRB_PHI:          59.14 [deg]
GRB_THETA:        17.68 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     19.51 [sigma]
IMAGE_SIGNIF:    8.47 [sigma]
MERIT_PARAMS:     +1  +0  +0  -1  +1  -1  +0  +0 -20  +0 
SUN_POSTN:        54.24d {+03h 36m 58s}  +19.38d {+19d 22' 49"}
SUN_DIST:         78.26 [deg]   Sun_angle= 3.7 [hr] (West of Sun)
MOON_POSTN:      118.95d {+07h 55m 48s}  +24.69d {+24d 41' 25"}
MOON_DIST:       128.41 [deg]
MOON_ILLUM:      25 [%]
GAL_COORDS:      344.85,-72.88 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      340.57,-34.67 [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 = 55.82,5.24 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 17 May 21 05:29:16 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     1048783,   Seg_Num: 0
POINT_RA:        358.181d {+23h 52m 43s} (J2000)
POINT_DEC:       -39.092d {-39d 05' 29"} (J2000)
IMG_START_DATE:  19351 TJD;   137 DOY;   21/05/17
IMG_START_TIME:  19748.65 SOD {05:29:08.65} UT,   67.1 [sec] since BAT Trigger Time
COUNTS:          1    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        0    Max_iter_allowed= 4
ERROR_CODE:      1
COMMENTS:        SWIFT-XRT Nack Position.  
COMMENTS:        No source found in the image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 17 May 21 05:32:01 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1048783,   Seg_Num: 0
POINT_RA:        358.181d {+23h 52m 44s} (J2000)
POINT_DEC:       -39.092d {-39d 05' 29"} (J2000)
POINT_ROLL:      53.004d
IMG_START_DATE:  19351 TJD;   137 DOY;   21/05/17
IMG_START_TIME:  19750.98 SOD {05:29:10.98} UT,   69.4 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.337
N_STARS:         15
X_OFFSET:        419 [pixels]
Y_OFFSET:        655 [pixels]
X_MAX:           1378 [pixels]
Y_MAX:           1614 [pixels]
DET_THRESH:      15
PHOTO_THRESH:    8
SL_URL:          sw01048783000msufc0069.fits
SUN_POSTN:        54.24d {+03h 36m 59s}  +19.38d {+19d 22' 51"}
SUN_DIST:         78.25 [deg]   Sun_angle= 3.7 [hr] (West of Sun)
MOON_POSTN:      118.99d {+07h 55m 57s}  +24.69d {+24d 41' 10"}
MOON_DIST:       128.43 [deg]
MOON_ILLUM:      25 [%]
GAL_COORDS:      344.88,-72.89 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      340.58,-34.66 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 17 May 21 05:32:18 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1048783,   Seg_Num: 0
POINT_RA:        358.181d {+23h 52m 44s} (J2000)
POINT_DEC:       -39.092d {-39d 05' 29"} (J2000)
POINT_ROLL:      53.004d
IMG_START_DATE:  19351 TJD;   137 DOY;   21/05/17
IMG_START_TIME:  19750.98 SOD {05:29:10.98} UT,   69.4 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.337
N_STARS:         15
X_OFFSET:        419 [pixels]
Y_OFFSET:        655 [pixels]
X_MAX:           1378 [pixels]
Y_MAX:           1614 [pixels]
DET_THRESH:      15
PHOTO_THRESH:    8
SL_URL:          sw01048783000msufc0069.fits
SUN_POSTN:        54.24d {+03h 36m 59s}  +19.38d {+19d 22' 52"}
SUN_DIST:         78.25 [deg]   Sun_angle= 3.7 [hr] (West of Sun)
MOON_POSTN:      118.99d {+07h 55m 57s}  +24.69d {+24d 41' 09"}
MOON_DIST:       128.43 [deg]
MOON_ILLUM:      25 [%]
GAL_COORDS:      344.88,-72.89 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      340.58,-34.66 [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 17 May 21 05:33:23 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1048783,   Seg_Num: 0
POINT_RA:        358.181d {+23h 52m 44s} (J2000)
POINT_DEC:       -39.092d {-39d 05' 29"} (J2000)
ROLL:            53.004d
IMG_START_DATE:  19351 TJD;   137 DOY;   21/05/17
IMG_START_TIME:  19750.98 SOD {05:29:10.98} UT,   69.4 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     642922178
X_OFFSET:        738 [pixels]
Y_OFFSET:        974 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       898
Y_GRB_POS:       1134
BINNING_INDEX:   1
IM_URL:          sw01048783000msuni0097.fits
SUN_POSTN:        54.25d {+03h 36m 59s}  +19.38d {+19d 22' 52"}
SUN_DIST:         78.25 [deg]   Sun_angle= 3.7 [hr] (West of Sun)
MOON_POSTN:      119.00d {+07h 56m 00s}  +24.68d {+24d 41' 04"}
MOON_DIST:       128.43 [deg]
MOON_ILLUM:      25 [%]
GAL_COORDS:      344.88,-72.89 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      340.58,-34.66 [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 17 May 21 05:32:49 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     1048783,   Seg_Num: 0
GRB_RA:          358.2210d {+23h 52m 53.04s} (J2000),
                 358.4976d {+23h 53m 59.43s} (current),
                 357.5721d {+23h 50m 17.31s} (1950)
GRB_DEC:         -39.1054d {-39d 06' 19.4"} (J2000),
                 -38.9865d {-38d 59' 11.2"} (current),
                 -39.3836d {-39d 23' 01.0"} (1950)
GRB_ERROR:       3.9 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  19351 TJD;   137 DOY;   21/05/17
IMG_START_TIME:  19766.00 SOD {05:29:26.00} UT,   84.4 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:        54.25d {+03h 36m 59s}  +19.38d {+19d 22' 52"}
SUN_DIST:         78.23 [deg]   Sun_angle= 3.7 [hr] (West of Sun)
MOON_POSTN:      118.99d {+07h 55m 58s}  +24.69d {+24d 41' 07"}
MOON_DIST:       128.40 [deg]
MOON_ILLUM:      25 [%]
GAL_COORDS:      344.77,-72.90 [deg] galactic lon,lat of the burst
ECL_COORDS:      340.61,-34.69 [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:     Mon 17 May 21 05:33:36 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1048783,   Seg_Num: 0
POINT_RA:        358.181d {+23h 52m 44s} (J2000)
POINT_DEC:       -39.092d {-39d 05' 29"} (J2000)
ROLL:            53.004d
IMG_START_DATE:  19351 TJD;   137 DOY;   21/05/17
IMG_START_TIME:  19750.98 SOD {05:29:10.98} UT,   69.4 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     642922178
X_OFFSET:        738 [pixels]
Y_OFFSET:        974 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       898
Y_GRB_POS:       1134
BINNING_INDEX:   1
IM_URL:          sw01048783000msuni0097.fits
SUN_POSTN:        54.25d {+03h 36m 59s}  +19.38d {+19d 22' 52"}
SUN_DIST:         78.25 [deg]   Sun_angle= 3.7 [hr] (West of Sun)
MOON_POSTN:      119.00d {+07h 56m 00s}  +24.68d {+24d 41' 04"}
MOON_DIST:       128.44 [deg]
MOON_ILLUM:      25 [%]
GAL_COORDS:      344.88,-72.89 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      340.58,-34.66 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 17 May 21 05:39:29 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1048783,   Seg_Num: 0
POINT_RA:        358.182d {+23h 52m 44s} (J2000)
POINT_DEC:       -39.090d {-39d 05' 23"} (J2000)
POINT_ROLL:      53.003d
IMG_START_DATE:  19351 TJD;   137 DOY;   21/05/17
IMG_START_TIME:  19963.23 SOD {05:32:43.23} UT,   281.7 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.457
N_STARS:         31
X_OFFSET:        179 [pixels]
Y_OFFSET:        415 [pixels]
X_MAX:           1618 [pixels]
Y_MAX:           1854 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw01048783000msufc0281.fits
SUN_POSTN:        54.25d {+03h 37m 00s}  +19.38d {+19d 22' 56"}
SUN_DIST:         78.25 [deg]   Sun_angle= 3.7 [hr] (West of Sun)
MOON_POSTN:      119.06d {+07h 56m 13s}  +24.68d {+24d 40' 40"}
MOON_DIST:       128.47 [deg]
MOON_ILLUM:      25 [%]
GAL_COORDS:      344.88,-72.89 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      340.59,-34.66 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 17 May 21 05:39:43 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1048783,   Seg_Num: 0
POINT_RA:        358.182d {+23h 52m 44s} (J2000)
POINT_DEC:       -39.090d {-39d 05' 23"} (J2000)
POINT_ROLL:      53.003d
IMG_START_DATE:  19351 TJD;   137 DOY;   21/05/17
IMG_START_TIME:  19963.23 SOD {05:32:43.23} UT,   281.7 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.457
N_STARS:         31
X_OFFSET:        179 [pixels]
Y_OFFSET:        415 [pixels]
X_MAX:           1618 [pixels]
Y_MAX:           1854 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw01048783000msufc0281.fits
SUN_POSTN:        54.25d {+03h 37m 00s}  +19.38d {+19d 22' 56"}
SUN_DIST:         78.25 [deg]   Sun_angle= 3.7 [hr] (West of Sun)
MOON_POSTN:      119.06d {+07h 56m 14s}  +24.68d {+24d 40' 39"}
MOON_DIST:       128.48 [deg]
MOON_ILLUM:      25 [%]
GAL_COORDS:      344.88,-72.89 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      340.59,-34.66 [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 17 May 21 05:39:52 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     1048783,   Seg_Num: 0
GRB_RA:          358.2246d {+23h 52m 53.90s} (J2000),
                 358.5012d {+23h 54m 00.29s} (current),
                 357.5758d {+23h 50m 18.18s} (1950)
GRB_DEC:         -39.1022d {-39d 06' 07.9"} (J2000),
                 -38.9833d {-38d 58' 59.7"} (current),
                 -39.3804d {-39d 22' 49.5"} (1950)
GRB_ERROR:       2.2 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  19351 TJD;   137 DOY;   21/05/17
IMG_START_TIME:  19766.00 SOD {05:29:26.00} UT,   84.4 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:        54.25d {+03h 37m 00s}  +19.38d {+19d 22' 56"}
SUN_DIST:         78.23 [deg]   Sun_angle= 3.7 [hr] (West of Sun)
MOON_POSTN:      119.06d {+07h 56m 14s}  +24.68d {+24d 40' 39"}
MOON_DIST:       128.44 [deg]
MOON_ILLUM:      25 [%]
GAL_COORDS:      344.78,-72.91 [deg] galactic lon,lat of the burst
ECL_COORDS:      340.61,-34.69 [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:     Mon 17 May 21 05:41:01 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1048783,   Seg_Num: 0
POINT_RA:        358.182d {+23h 52m 44s} (J2000)
POINT_DEC:       -39.090d {-39d 05' 23"} (J2000)
ROLL:            53.003d
IMG_START_DATE:  19351 TJD;   137 DOY;   21/05/17
IMG_START_TIME:  19963.23 SOD {05:32:43.23} UT,   281.7 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     642922390
X_OFFSET:        738 [pixels]
Y_OFFSET:        974 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       898
Y_GRB_POS:       1134
BINNING_INDEX:   1
IM_URL:          sw01048783000msuni0309.fits
SUN_POSTN:        54.25d {+03h 37m 00s}  +19.38d {+19d 22' 56"}
SUN_DIST:         78.25 [deg]   Sun_angle= 3.7 [hr] (West of Sun)
MOON_POSTN:      119.07d {+07h 56m 17s}  +24.68d {+24d 40' 34"}
MOON_DIST:       128.48 [deg]
MOON_ILLUM:      25 [%]
GAL_COORDS:      344.88,-72.89 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      340.59,-34.66 [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 17 May 21 05:41:10 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1048783,   Seg_Num: 0
POINT_RA:        358.182d {+23h 52m 44s} (J2000)
POINT_DEC:       -39.090d {-39d 05' 23"} (J2000)
ROLL:            53.003d
IMG_START_DATE:  19351 TJD;   137 DOY;   21/05/17
IMG_START_TIME:  19963.23 SOD {05:32:43.23} UT,   281.7 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     642922390
X_OFFSET:        738 [pixels]
Y_OFFSET:        974 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       898
Y_GRB_POS:       1134
BINNING_INDEX:   1
IM_URL:          sw01048783000msuni0309.fits
SUN_POSTN:        54.25d {+03h 37m 00s}  +19.38d {+19d 22' 56"}
SUN_DIST:         78.25 [deg]   Sun_angle= 3.7 [hr] (West of Sun)
MOON_POSTN:      119.07d {+07h 56m 17s}  +24.68d {+24d 40' 34"}
MOON_DIST:       128.49 [deg]
MOON_ILLUM:      25 [%]
GAL_COORDS:      344.88,-72.89 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      340.59,-34.66 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        If you have elected to receive attachments:  
COMMENTS:        The uvot_catalog_image.fits.gz file does not exist; skipping the attachment.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 17 May 21 05:45:15 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1048783,   Seg_Num: 0
POINT_RA:        358.181d {+23h 52m 43s} (J2000)
POINT_DEC:       -39.090d {-39d 05' 23"} (J2000)
POINT_ROLL:      53.003d
IMG_START_DATE:  19351 TJD;   137 DOY;   21/05/17
IMG_START_TIME:  20541.25 SOD {05:42:21.25} UT,   859.7 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        5.110
N_STARS:         58
X_OFFSET:        179 [pixels]
Y_OFFSET:        415 [pixels]
X_MAX:           1618 [pixels]
Y_MAX:           1854 [pixels]
DET_THRESH:      19
PHOTO_THRESH:    11
SL_URL:          sw01048783000msufc0859.fits
SUN_POSTN:        54.25d {+03h 37m 01s}  +19.38d {+19d 22' 59"}
SUN_DIST:         78.26 [deg]   Sun_angle= 3.7 [hr] (West of Sun)
MOON_POSTN:      119.11d {+07h 56m 26s}  +24.67d {+24d 40' 17"}
MOON_DIST:       128.51 [deg]
MOON_ILLUM:      25 [%]
GAL_COORDS:      344.88,-72.89 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      340.59,-34.66 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 17 May 21 05:45:24 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1048783,   Seg_Num: 0
POINT_RA:        358.181d {+23h 52m 43s} (J2000)
POINT_DEC:       -39.090d {-39d 05' 23"} (J2000)
POINT_ROLL:      53.003d
IMG_START_DATE:  19351 TJD;   137 DOY;   21/05/17
IMG_START_TIME:  20541.25 SOD {05:42:21.25} UT,   859.7 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        5.110
N_STARS:         58
X_OFFSET:        179 [pixels]
Y_OFFSET:        415 [pixels]
X_MAX:           1618 [pixels]
Y_MAX:           1854 [pixels]
DET_THRESH:      19
PHOTO_THRESH:    11
SL_URL:          sw01048783000msufc0859.fits
SUN_POSTN:        54.25d {+03h 37m 01s}  +19.38d {+19d 22' 59"}
SUN_DIST:         78.26 [deg]   Sun_angle= 3.7 [hr] (West of Sun)
MOON_POSTN:      119.11d {+07h 56m 27s}  +24.67d {+24d 40' 17"}
MOON_DIST:       128.51 [deg]
MOON_ILLUM:      25 [%]
GAL_COORDS:      344.88,-72.89 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      340.59,-34.66 [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 17 May 21 05:47:21 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1048783,   Seg_Num: 0
POINT_RA:        358.181d {+23h 52m 43s} (J2000)
POINT_DEC:       -39.090d {-39d 05' 23"} (J2000)
ROLL:            53.003d
IMG_START_DATE:  19351 TJD;   137 DOY;   21/05/17
IMG_START_TIME:  20541.25 SOD {05:42:21.25} UT,   859.7 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     642922968
X_OFFSET:        738 [pixels]
Y_OFFSET:        974 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       898
Y_GRB_POS:       1134
BINNING_INDEX:   1
IM_URL:          sw01048783000msuni0887.fits
SUN_POSTN:        54.26d {+03h 37m 01s}  +19.38d {+19d 22' 60"}
SUN_DIST:         78.26 [deg]   Sun_angle= 3.7 [hr] (West of Sun)
MOON_POSTN:      119.13d {+07h 56m 31s}  +24.67d {+24d 40' 09"}
MOON_DIST:       128.53 [deg]
MOON_ILLUM:      25 [%]
GAL_COORDS:      344.88,-72.89 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      340.59,-34.66 [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 17 May 21 05:47:36 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1048783,   Seg_Num: 0
POINT_RA:        358.181d {+23h 52m 43s} (J2000)
POINT_DEC:       -39.090d {-39d 05' 23"} (J2000)
ROLL:            53.003d
IMG_START_DATE:  19351 TJD;   137 DOY;   21/05/17
IMG_START_TIME:  20541.25 SOD {05:42:21.25} UT,   859.7 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     642922968
X_OFFSET:        738 [pixels]
Y_OFFSET:        974 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       898
Y_GRB_POS:       1134
BINNING_INDEX:   1
IM_URL:          sw01048783000msuni0887.fits
SUN_POSTN:        54.26d {+03h 37m 01s}  +19.38d {+19d 23' 00"}
SUN_DIST:         78.26 [deg]   Sun_angle= 3.7 [hr] (West of Sun)
MOON_POSTN:      119.13d {+07h 56m 31s}  +24.67d {+24d 40' 08"}
MOON_DIST:       128.53 [deg]
MOON_ILLUM:      25 [%]
GAL_COORDS:      344.88,-72.89 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      340.59,-34.66 [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 #30032
V. D'Elia (SSDC & INAF-OAR), E. Ambrosi (INAF-IASFPA), A. D'Ai (INAF-IASFPA), J.D. Gropp (PSU), H. A. Krimm (NSF), A. Y. Lien (GSFC/UMBC), K. L. Page (U Leicester), D. M. Palmer (LANL), B. Sbarufatti (PSU), M. H. Siegel (PSU) and A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift Observatory Team:
At 05:28:01 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 210517A (trigger=1048783). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 358.174, -39.105 which is
```
   RA(J2000) = 23h 52m 42s
   Dec(J2000) = -39d 06' 17"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT lightcurve shows a peak at least 2 seconds long and a maximum count rate of ~2200 counts/s (15-350 keV).
The XRT began observing the field at 05:29:08.6 UT, 67.0 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source with an enhanced position: RA, Dec 358.2245, -39.1020 which is equivalent to:
```
   RA(J2000)  = 23h 52m 53.88s
   Dec(J2000) = -39d 06' 07.2"
```
with an uncertainty of 2.1 arcseconds (radius, 90% containment). This location is 141 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 (1.30 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 5.2 (+2.58/-2.26) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 69 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers none of the XRT error circle. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.011.
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 Circular #30033
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-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) was pointed to the Swift GRB210517.23 (trigger No 1048783,23h 52m 41.76s , -39d 06m 18.0s, R=0.05) errorbox 40 sec after notice time and 254 sec after trigger time at 2021-05-17 05:32:16 UT, with upper limit up to 16.2 mag. The observations began at zenith distance = 83 deg. The sun altitude is -71.9 deg.
The galactic latitude b = -73 deg., longitude l = 344 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1614656
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

     280 |         MASTER-OAFA |   C |    50 | 16.2 |        
     486 |         MASTER-OAFA |   C |    90 | 15.4 |        
     784 |         MASTER-OAFA |   C |   140 | 15.8 |        
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
GCN Circular #30034
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team.
Using 1271 s of XRT Photon Counting mode data and 2 UVOT images for GRB 210517A, 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 = 358.22445, -39.10218 which is equivalent to:
```
RA (J2000): 23h 52m 53.87s
Dec (J2000): -39d 06' 07.9"
```
with an uncertainty of 2.2 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 #30036
A. Ursi (INAF/IAPS), C. Pittori (SSDC, and INAF/OAR), G. Piano (INAF/IAPS), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), A. Argan, M. Cardillo, C. Casentini, Y. Evangelista (INAF/IAPS), F. Lucarelli, F. Verrecchia (SSDC, and INAF/OAR), A. Bulgarelli, A. Di Piano, V. Fioretti, F. Fuschino, N. Parmiggiani (INAF/OAS-Bologna), M. Marisaldi (INAF/OAS-Bologna, and Bergen University), M. Pilia, A. Trois (INAF/OA-Cagliari), I. Donnarumma (ASI), F. Longo (Univ. Trieste and INFN Trieste), A. Giuliani (INAF/IASF-Mi), report on behalf of the AGILE Team:
The AGILE satellite detected the long GRB 210517A at T0 = 2021-05-17 05:28:01 s (UTC), reported by Swift (GCNs #30032, #30034).
The burst is visible in the AGILE scientific ratemeters of the SuperAGILE (SA; 20-60 keV) and MiniCALorimeter (MCAL; 0.4-100 MeV) detectors. The event lasted ~6 s and released a total number of 663 counts in the SA detector (above a background rate of 77 Hz) and 8759 counts in the MCAL detector (above a background rate of 1200 Hz). The AGILE ratemeter light curves can be found at http://www.agilescienceapp.it/notices/GRB210517A_AGILE_RM.png .
Additional analysis of AGILE data is in progress.
GCN Circular #30037
N. R. Tanvir (Univ. Leicester), D. Xu (NAOC/CAS), L. Izzo (DARK/NBI), D. A. Kann (HETH/IAA-CSIC), D. B. Malesani (DTU space), J.-B. Vielfaure (APC), P. Jakobsson (Univ. Iceland), A. de Ugarte Postigo (HETH/IAA-CSIC and DARK/NBI), K. E. Heintz (Univ. Iceland and DAWN/NBI), V. D'Elia (ASI/SSDC), A. J. Levan (Radboud Univ.), S. D. Vergani (CNRS, Paris Obs.), S. Campana (INAF/Brera), G. Pugliese (Amsterdam), report on behalf of the Stargate collaboration:
We observed the field of GRB 210517A (D'Elia et al., GCN 30032; Ursi et al., GCN 30036) using the ESO VLT UT3 (Melipal) equipped with the X-shooter spectrograph. Our spectra cover the wavelength range 3000-21000 AA, and consist of 4 exposures by 600 s each. The observation mid time was 2021 May 17.387 UT (3.82 hr after the GRB).
In a 30 s image taken with the acquisition camera on May 17.364 UT, we detect a single object consistent with the UVOT-enhanced XRT position (Beardmore et al., GCN 30034), at J2000 coordinates:
```
RA = 23:52:53.95
Dec = -39:06:08.3
```
We measure for this target an AB magnitude r = 22.3 +- 0.1 (calibrated against the Legacy Survey, but only very few, faint stars are present in the acquisition camera field of view). We note that at the same position, to within the uncertainties, there is a faint object visible in the Legacy Survey, with AB magnitude r ~ 23.7. We conclude that the above source is the optical afterglow of GRB 210517A, and the archival object is its host galaxy.
In our spectra, continuum is detected over the whole observed range. A prominent emission line is detected around 4236 AA, which we identify as Ly alpha in emission. This interpretation is confirmed by the detection of both emission lines in the near-infrared arm (corresponding to [O II] and [O III]), and a plethora of metallic absorption features, among them Si II, Si IV, O I, C IV, C II, all at a common redshift z = 2.486. Consistent with the detection of bright Ly alpha in emission, the observed HI absorption column density is low.
We note that at z = 2.486 the galaxy is a particularly bright GRB host, with an absolute AB magnitude M(1800 AA) ~ -21.5.
We acknowledge excellent support from the ESO observing staff in Paranal, in particular Luca Sbordone, Francisco Caceres, and Boris Haeussler.
GCN Circular #30040
GRB 210517A: Swift/UVOT Upper Limits
S. J. LaPorte (PSU) and V. D'Elia (SSDC & INAF-OAR) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 210517A 69 s after the BAT trigger (D'Elia et al., GCN Circ. 30032). No optical afterglow consistent with the optical position (Tanvir et al. GCN Circ. 30037) 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            69          219          147         >19.4
u_FC               282          531          246         >19.7
white               69         1356          373         >19.9
v                  611         5047          274         >19.0
b                  537         1332           78         >19.5
u                  282         1307          304         >19.7
w1                 661         1109           39         >18.4
m2                5052         5070           18         >18.7
w2                4642         4841          197         >21.1
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.011 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #30042
K.L. Page (U. Leicester), M. Capalbi (INAF-IASFPA), M. Perri (SSDC & INAF-OAR), D.N. Burrows (PSU), J. D. Gropp (PSU), J.A. Kennea (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester) and V. D'Elia report on behalf of the Swift-XRT team:
We have analysed 7.7 ks of XRT data for GRB 210517A (D'Elia et al. GCN Circ. 30032), from 85 s to 40.6 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN Circ. 30034).
The light curve can be modelled with a power-law decay with a decay index of alpha=0.90 (+/-0.06).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.71 (+0.18, -0.14). The best-fitting absorption column is 1.4 (+7.0, -1.4) x 10^21 cm^-2, at a redshift of 2.486, in addition to the Galactic value of 1.3 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 3.7 x 10^-11 (3.9 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Galactic foreground: 1.3 x 10^20 cm^-2
Intrinsic column:    1.4 (+7.0, -1.4) x 10^21 cm^-2 at z=2.486
Photon index:	     1.71 (+0.18, -0.14)
```
If the light curve continues to decay with a power-law decay index of 0.90, the count rate at T+24 hours will be 3.0 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.1 x 10^-13 (1.2 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/01048783.
This circular is an official product of the Swift-XRT team.
GCN Circular #30043
T. Sakamoto (AGU), S. D. Barthelmy (GSFC), V. D'Elia (SSDC & INAF-OAR), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+659 sec from the recent telemetry downlink, we report further analysis of BAT GRB 210517A (trigger #1048783) (D'Elia, et al., GCN Circ. 30032). The BAT ground-calculated position is RA, Dec = 358.190, -39.104 deg which is
```
   RA(J2000)  =  23h 52m 45.5s 
   Dec(J2000) = -39d 06' 15.0" 
```
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 78%.
The mask-weighted light curve shows a single peak of three-second duration near the trigger time. T90 (15-350 keV) is 3.06 +- 1.4 sec (estimated error including systematics).
The time-averaged spectrum from T-0.17 to T+3.13 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.85 +- 0.25. The fluence in the 15-150 keV band is 1.5 +- 0.3 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T-0.18 sec in the 15-150 keV band is 1.5 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
The position of this burst on the BAT T90-Hardness diagram suggests that it is a long GRB.
The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/1048783/BA/
GCN Circular #30057
Gregory S.H. Paek (SNU ARC/SNU), Myungshin Im (SNU ARC/SNU), Gu Lim (SNU ARC/SNU), on behalf of GECKO collaboration
We searched for the optical counterpart of GRB 210517A (V. E'Elia et al. GCN #30032) with the 0.36-m class KCT (KIAS Chamnun Telescope) in DeepSkyChile, one of the facilities of the GW EM-Counterpart Korean Observatory (GECKO).
We observed the center of Swift/XRT localization (RA, Dec = 358.2245 -39.1020) +2.94 hours after report, but could not find any possible transient within the field of view and at the reported location of optical afterglow (N. R. Tanvir et al. GCN 30037). We calibrated flux with the APASS catalog and used an AB magnitude system. Depth means 5 sigma upper limit for a point source detection. The magnitudes are not corrected for galactic extinction.
```
------
Filter Date-obs[UT] Exp.time[s] Depth
I 2021-05-17T08:24:35.583 180*3 18.435
R 2021-05-17T08:37:00.750 180*3 19.581
V 2021-05-17T08:49:25.333 180*3 20.005
B 2021-05-17T09:01:50.250 180*3 20.047
```
Gravitational-wave EM Counterpart Korean Observatory (GECKO) is a network of 10+ 0.5m to 1m class telescopes over the world.

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Jochen Greiner, last update: 20-May-2021 [Disclaimer]