Gamma-ray Burst 200917A

(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 17 Sep 20 03:53:15 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     996184,   Seg_Num: 0
GRB_RA:          235.753d {+15h 43m 01s} (J2000),
                 236.027d {+15h 44m 06s} (current),
                 235.094d {+15h 40m 23s} (1950)
GRB_DEC:          -4.695d {-04d 41' 42"} (J2000),
                  -4.760d {-04d 45' 35"} (current),
                  -4.537d {-04d 32' 13"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       14570 [cnts]    Image_Peak=405 [image_cnts]
TRIGGER_DUR:     4.096 [sec] 
TRIGGER_INDEX:   289     E_range: 15-50 keV
BKG_INTEN:       125748 [cnts]
BKG_TIME:        13894.35 SOD {03:51:34.35} UT
BKG_DUR:         40 [sec]
GRB_DATE:        19109 TJD;   261 DOY;   20/09/17
GRB_TIME:        13948.30 SOD {03:52:28.30} UT
GRB_PHI:         142.72 [deg]
GRB_THETA:        12.50 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     14.00 [sigma]
IMAGE_SIGNIF:    9.11 [sigma]
MERIT_PARAMS:     +1  +0  +0  +2  +1  +0  +0  +0 -48  +0 
SUN_POSTN:       175.16d {+11h 40m 38s}   +2.09d {+02d 05' 42"}
SUN_DIST:         61.20 [deg]   Sun_angle= -4.1 [hr] (East of Sun)
MOON_POSTN:      173.12d {+11h 32m 28s}   +8.37d {+08d 22' 04"}
MOON_DIST:        64.09 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:        2.04, 37.77 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      234.57, 14.63 [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 = 148.85,20.29 [deg].

red DSS finding chart ps-file

GCN NOTICE

 
TITLE:           GCN/SWIFT NOTICE 
NOTICE_DATE:     Thu 17 Sep 20 03:54:14 UT 
NOTICE_TYPE:     Swift-XRT Nack-Position 
TRIGGER_NUM:     996184,   Seg_Num: 0 
POINT_RA:        235.753d {+15h 43m 01s} (J2000) 
POINT_DEC:        -4.696d {-04d 41' 44"} (J2000) 
IMG_START_DATE:  19109 TJD;   261 DOY;   20/09/17 
IMG_START_TIME:  14049.07 SOD {03:54:09.07} UT,   100.8 [sec] since BAT Trigger Time 
COUNTS:          5    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 17 Sep 20 03:56:01 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     996184,   Seg_Num: 0
GRB_RA:          235.753d {+15h 43m 01s} (J2000),
                 236.027d {+15h 44m 06s} (current),
                 235.094d {+15h 40m 23s} (1950)
GRB_DEC:          -4.695d {-04d 41' 42"} (J2000),
                  -4.760d {-04d 45' 35"} (current),
                  -4.537d {-04d 32' 13"} (1950)
GRB_DATE:        19109 TJD;   261 DOY;   20/09/17
GRB_TIME:        13948.30 SOD {03:52:28.30} UT
TRIGGER_INDEX:   289
GRB_PHI:         142.72 [deg]
GRB_THETA:        12.50 [deg]
DELTA_TIME:      45.00 [sec]
TRIGGER_DUR:     4.096 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     14.00 [sigma]
IMAGE_SIGNIF:    9.11 [sigma]
LC_URL:          sw00996184000msb.lc
SUN_POSTN:       175.16d {+11h 40m 38s}   +2.09d {+02d 05' 39"}
SUN_DIST:         61.20 [deg]   Sun_angle= -4.1 [hr] (East of Sun)
MOON_POSTN:      173.14d {+11h 32m 34s}   +8.36d {+08d 21' 24"}
MOON_DIST:        64.07 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:        2.04, 37.77 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      234.57, 14.63 [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 = 148.85,20.29 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 17 Sep 20 03:57:27 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     996184,   Seg_Num: 0
POINT_RA:        235.753d {+15h 43m 01s} (J2000)
POINT_DEC:        -4.696d {-04d 41' 43"} (J2000)
POINT_ROLL:      274.987d
IMG_START_DATE:  19109 TJD;   261 DOY;   20/09/17
IMG_START_TIME:  14052.69 SOD {03:54:12.69} UT,   104.4 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.421
N_STARS:         41
X_OFFSET:        468 [pixels]
Y_OFFSET:        558 [pixels]
X_MAX:           1427 [pixels]
Y_MAX:           1517 [pixels]
DET_THRESH:      18
PHOTO_THRESH:    10
SL_URL:          sw00996184000msufc0104.fits
SUN_POSTN:       175.16d {+11h 40m 39s}   +2.09d {+02d 05' 38"}
SUN_DIST:         61.19 [deg]   Sun_angle= -4.1 [hr] (East of Sun)
MOON_POSTN:      173.16d {+11h 32m 38s}   +8.35d {+08d 21' 03"}
MOON_DIST:        64.05 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:        2.04, 37.77 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      234.57, 14.63 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 17 Sep 20 03:57:49 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     996184,   Seg_Num: 0
POINT_RA:        235.753d {+15h 43m 01s} (J2000)
POINT_DEC:        -4.696d {-04d 41' 43"} (J2000)
POINT_ROLL:      274.987d
IMG_START_DATE:  19109 TJD;   261 DOY;   20/09/17
IMG_START_TIME:  14052.69 SOD {03:54:12.69} UT,   104.4 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.421
N_STARS:         41
X_OFFSET:        468 [pixels]
Y_OFFSET:        558 [pixels]
X_MAX:           1427 [pixels]
Y_MAX:           1517 [pixels]
DET_THRESH:      18
PHOTO_THRESH:    10
SL_URL:          sw00996184000msufc0104.fits
SUN_POSTN:       175.16d {+11h 40m 39s}   +2.09d {+02d 05' 37"}
SUN_DIST:         61.19 [deg]   Sun_angle= -4.1 [hr] (East of Sun)
MOON_POSTN:      173.16d {+11h 32m 39s}   +8.35d {+08d 20' 57"}
MOON_DIST:        64.05 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:        2.04, 37.77 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      234.57, 14.63 [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 17 Sep 20 03:58:50 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     996184,   Seg_Num: 0
POINT_RA:        235.753d {+15h 43m 01s} (J2000)
POINT_DEC:        -4.696d {-04d 41' 43"} (J2000)
ROLL:            274.987d
IMG_START_DATE:  19109 TJD;   261 DOY;   20/09/17
IMG_START_TIME:  14052.69 SOD {03:54:12.69} UT,   104.4 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     622007678
X_OFFSET:        787 [pixels]
Y_OFFSET:        877 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       947
Y_GRB_POS:       1037
BINNING_INDEX:   1
IM_URL:          sw00996184000msuni0130.fits
SUN_POSTN:       175.16d {+11h 40m 39s}   +2.09d {+02d 05' 36"}
SUN_DIST:         61.19 [deg]   Sun_angle= -4.1 [hr] (East of Sun)
MOON_POSTN:      173.17d {+11h 32m 41s}   +8.35d {+08d 20' 43"}
MOON_DIST:        64.04 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:        2.04, 37.77 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      234.57, 14.63 [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 17 Sep 20 03:58:07 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     996184,   Seg_Num: 0
GRB_RA:          235.7250d {+15h 42m 53.99s} (J2000),
                 235.9983d {+15h 44m 00.41s} (current),
                 235.0660d {+15h 40m 15.82s} (1950)
GRB_DEC:          -4.7020d {-04d 42' 07.1"} (J2000),
                  -4.7667d {-04d 46' 00.1"} (current),
                  -4.5439d {-04d 32' 38.0"} (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:  19109 TJD;   261 DOY;   20/09/17
IMG_START_TIME:  14060.00 SOD {03:54:20.00} UT,   111.7 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       175.16d {+11h 40m 39s}   +2.09d {+02d 05' 37"}
SUN_DIST:         61.17 [deg]   Sun_angle= -4.1 [hr] (East of Sun)
MOON_POSTN:      173.16d {+11h 32m 39s}   +8.35d {+08d 20' 53"}
MOON_DIST:        64.02 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:        2.01, 37.79 [deg] galactic lon,lat of the burst
ECL_COORDS:      234.55, 14.62 [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 17 Sep 20 03:59:06 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     996184,   Seg_Num: 0
POINT_RA:        235.753d {+15h 43m 01s} (J2000)
POINT_DEC:        -4.696d {-04d 41' 43"} (J2000)
ROLL:            274.987d
IMG_START_DATE:  19109 TJD;   261 DOY;   20/09/17
IMG_START_TIME:  14052.69 SOD {03:54:12.69} UT,   104.4 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     622007678
X_OFFSET:        787 [pixels]
Y_OFFSET:        877 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       947
Y_GRB_POS:       1037
BINNING_INDEX:   1
IM_URL:          sw00996184000msuni0130.fits
SUN_POSTN:       175.16d {+11h 40m 39s}   +2.09d {+02d 05' 36"}
SUN_DIST:         61.19 [deg]   Sun_angle= -4.1 [hr] (East of Sun)
MOON_POSTN:      173.17d {+11h 32m 41s}   +8.34d {+08d 20' 39"}
MOON_DIST:        64.03 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:        2.04, 37.77 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      234.57, 14.63 [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 17 Sep 20 04:04:13 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     996184,   Seg_Num: 0
POINT_RA:        235.752d {+15h 43m 01s} (J2000)
POINT_DEC:        -4.695d {-04d 41' 42"} (J2000)
POINT_ROLL:      274.985d
IMG_START_DATE:  19109 TJD;   261 DOY;   20/09/17
IMG_START_TIME:  14210.54 SOD {03:56:50.54} UT,   262.2 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.119
N_STARS:         62
X_OFFSET:        228 [pixels]
Y_OFFSET:        318 [pixels]
X_MAX:           1667 [pixels]
Y_MAX:           1757 [pixels]
DET_THRESH:      9
PHOTO_THRESH:    4
SL_URL:          sw00996184000msufc0262.fits
SUN_POSTN:       175.17d {+11h 40m 40s}   +2.09d {+02d 05' 31"}
SUN_DIST:         61.19 [deg]   Sun_angle= -4.1 [hr] (East of Sun)
MOON_POSTN:      173.22d {+11h 32m 53s}   +8.32d {+08d 19' 24"}
MOON_DIST:        63.98 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:        2.04, 37.77 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      234.57, 14.63 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 17 Sep 20 04:04:26 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     996184,   Seg_Num: 0
POINT_RA:        235.752d {+15h 43m 01s} (J2000)
POINT_DEC:        -4.695d {-04d 41' 42"} (J2000)
POINT_ROLL:      274.985d
IMG_START_DATE:  19109 TJD;   261 DOY;   20/09/17
IMG_START_TIME:  14210.54 SOD {03:56:50.54} UT,   262.2 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.119
N_STARS:         62
X_OFFSET:        228 [pixels]
Y_OFFSET:        318 [pixels]
X_MAX:           1667 [pixels]
Y_MAX:           1757 [pixels]
DET_THRESH:      9
PHOTO_THRESH:    4
SL_URL:          sw00996184000msufc0262.fits
SUN_POSTN:       175.17d {+11h 40m 40s}   +2.09d {+02d 05' 31"}
SUN_DIST:         61.19 [deg]   Sun_angle= -4.1 [hr] (East of Sun)
MOON_POSTN:      173.22d {+11h 32m 54s}   +8.32d {+08d 19' 21"}
MOON_DIST:        63.98 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:        2.04, 37.77 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      234.57, 14.63 [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 17 Sep 20 04:05:41 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     996184,   Seg_Num: 0
POINT_RA:        235.752d {+15h 43m 01s} (J2000)
POINT_DEC:        -4.695d {-04d 41' 42"} (J2000)
ROLL:            274.985d
IMG_START_DATE:  19109 TJD;   261 DOY;   20/09/17
IMG_START_TIME:  14210.54 SOD {03:56:50.54} UT,   262.2 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     622007836
X_OFFSET:        787 [pixels]
Y_OFFSET:        877 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       947
Y_GRB_POS:       1037
BINNING_INDEX:   1
IM_URL:          sw00996184000msuni0288.fits
SUN_POSTN:       175.17d {+11h 40m 40s}   +2.09d {+02d 05' 30"}
SUN_DIST:         61.19 [deg]   Sun_angle= -4.1 [hr] (East of Sun)
MOON_POSTN:      173.24d {+11h 32m 57s}   +8.32d {+08d 19' 03"}
MOON_DIST:        63.97 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:        2.04, 37.77 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      234.57, 14.63 [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 17 Sep 20 04:04:43 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     996184,   Seg_Num: 0
GRB_RA:          235.7247d {+15h 42m 53.92s} (J2000),
                 235.9980d {+15h 44m 00.48s} (current),
                 235.0657d {+15h 40m 15.75s} (1950)
GRB_DEC:          -4.7011d {-04d 42' 03.9"} (J2000),
                  -4.7658d {-04d 45' 56.9"} (current),
                  -4.5430d {-04d 32' 34.7"} (1950)
GRB_ERROR:       2.3 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  19109 TJD;   261 DOY;   20/09/17
IMG_START_TIME:  14060.00 SOD {03:54:20.00} UT,   111.7 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       175.17d {+11h 40m 40s}   +2.09d {+02d 05' 31"}
SUN_DIST:         61.16 [deg]   Sun_angle= -4.1 [hr] (East of Sun)
MOON_POSTN:      173.23d {+11h 32m 54s}   +8.32d {+08d 19' 17"}
MOON_DIST:        63.95 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:        2.02, 37.79 [deg] galactic lon,lat of the burst
ECL_COORDS:      234.55, 14.62 [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 17 Sep 20 04:05:53 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     996184,   Seg_Num: 0
POINT_RA:        235.752d {+15h 43m 01s} (J2000)
POINT_DEC:        -4.695d {-04d 41' 42"} (J2000)
ROLL:            274.985d
IMG_START_DATE:  19109 TJD;   261 DOY;   20/09/17
IMG_START_TIME:  14210.54 SOD {03:56:50.54} UT,   262.2 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     622007836
X_OFFSET:        787 [pixels]
Y_OFFSET:        877 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       947
Y_GRB_POS:       1037
BINNING_INDEX:   1
IM_URL:          sw00996184000msuni0288.fits
SUN_POSTN:       175.17d {+11h 40m 40s}   +2.09d {+02d 05' 29"}
SUN_DIST:         61.19 [deg]   Sun_angle= -4.1 [hr] (East of Sun)
MOON_POSTN:      173.24d {+11h 32m 57s}   +8.32d {+08d 18' 60"}
MOON_DIST:        63.96 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:        2.04, 37.77 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      234.57, 14.63 [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 17 Sep 20 04:09:47 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     996184,   Seg_Num: 0
POINT_RA:        235.752d {+15h 43m 01s} (J2000)
POINT_DEC:        -4.695d {-04d 41' 41"} (J2000)
POINT_ROLL:      274.985d
IMG_START_DATE:  19109 TJD;   261 DOY;   20/09/17
IMG_START_TIME:  14813.18 SOD {04:06:53.18} UT,   864.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.030
N_STARS:         81
X_OFFSET:        228 [pixels]
Y_OFFSET:        318 [pixels]
X_MAX:           1667 [pixels]
Y_MAX:           1757 [pixels]
DET_THRESH:      17
PHOTO_THRESH:    9
SL_URL:          sw00996184000msufc0864.fits
SUN_POSTN:       175.17d {+11h 40m 41s}   +2.09d {+02d 05' 26"}
SUN_DIST:         61.19 [deg]   Sun_angle= -4.1 [hr] (East of Sun)
MOON_POSTN:      173.28d {+11h 33m 06s}   +8.30d {+08d 18' 03"}
MOON_DIST:        63.93 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:        2.04, 37.77 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      234.57, 14.63 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 17 Sep 20 04:10:10 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     996184,   Seg_Num: 0
POINT_RA:        235.752d {+15h 43m 01s} (J2000)
POINT_DEC:        -4.695d {-04d 41' 41"} (J2000)
POINT_ROLL:      274.985d
IMG_START_DATE:  19109 TJD;   261 DOY;   20/09/17
IMG_START_TIME:  14813.18 SOD {04:06:53.18} UT,   864.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.030
N_STARS:         81
X_OFFSET:        228 [pixels]
Y_OFFSET:        318 [pixels]
X_MAX:           1667 [pixels]
Y_MAX:           1757 [pixels]
DET_THRESH:      17
PHOTO_THRESH:    9
SL_URL:          sw00996184000msufc0864.fits
SUN_POSTN:       175.17d {+11h 40m 41s}   +2.09d {+02d 05' 25"}
SUN_DIST:         61.19 [deg]   Sun_angle= -4.1 [hr] (East of Sun)
MOON_POSTN:      173.28d {+11h 33m 07s}   +8.30d {+08d 17' 57"}
MOON_DIST:        63.92 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:        2.04, 37.77 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      234.57, 14.63 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN Circular #28435
E. Sonbas (Adiyaman Univ.), E. Ambrosi (INAF-IASFPA), S. D. Barthelmy (GSFC), A. D'Ai (INAF-IASFPA), N. J. Klingler (PSU), D. M. Palmer (LANL), B. Sbarufatti (PSU) and A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift Observatory Team:
At 03:52:28 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 200917A (trigger=996184). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 235.753, -4.695 which is
```
   RA(J2000)  =  15h 43m 01s
   Dec(J2000) = -04d 41' 42"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single peak with a duration of about 15 sec. The peak count rate was ~1200 counts/sec (15-350 keV), at ~1 sec after the trigger.
The XRT began observing the field at 03:54:09.0 UT, 100.8 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 235.7247, -4.7011 which is equivalent to:
```
   RA(J2000)  = 15h 42m 53.93s
   Dec(J2000) = -04d 42' 04.0"
```
with an uncertainty of 2.3 arcseconds (radius, 90% containment). This location is 103 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 in excess of the Galactic value (1.49 x 10^21 cm^-2, Willingale et al. 2013), with an excess column of 5.6 (+5.36/-4.35) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 104 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 0.19.
Burst Advocate for this burst is E. Sonbas (edasonbas AT yahoo.com). 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 17 Sep 20 04:11:46 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     996184,   Seg_Num: 0
POINT_RA:        235.752d {+15h 43m 01s} (J2000)
POINT_DEC:        -4.695d {-04d 41' 41"} (J2000)
ROLL:            274.985d
IMG_START_DATE:  19109 TJD;   261 DOY;   20/09/17
IMG_START_TIME:  14813.18 SOD {04:06:53.18} UT,   864.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     622008438
X_OFFSET:        787 [pixels]
Y_OFFSET:        877 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       947
Y_GRB_POS:       1037
BINNING_INDEX:   1
IM_URL:          sw00996184000msuni0890.fits
SUN_POSTN:       175.17d {+11h 40m 41s}   +2.09d {+02d 05' 24"}
SUN_DIST:         61.18 [deg]   Sun_angle= -4.1 [hr] (East of Sun)
MOON_POSTN:      173.29d {+11h 33m 11s}   +8.29d {+08d 17' 34"}
MOON_DIST:        63.91 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:        2.04, 37.77 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      234.57, 14.63 [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 17 Sep 20 04:12:01 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     996184,   Seg_Num: 0
POINT_RA:        235.752d {+15h 43m 01s} (J2000)
POINT_DEC:        -4.695d {-04d 41' 41"} (J2000)
ROLL:            274.985d
IMG_START_DATE:  19109 TJD;   261 DOY;   20/09/17
IMG_START_TIME:  14813.18 SOD {04:06:53.18} UT,   864.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     622008438
X_OFFSET:        787 [pixels]
Y_OFFSET:        877 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       947
Y_GRB_POS:       1037
BINNING_INDEX:   1
IM_URL:          sw00996184000msuni0890.fits
SUN_POSTN:       175.17d {+11h 40m 41s}   +2.09d {+02d 05' 24"}
SUN_DIST:         61.18 [deg]   Sun_angle= -4.1 [hr] (East of Sun)
MOON_POSTN:      173.30d {+11h 33m 11s}   +8.29d {+08d 17' 30"}
MOON_DIST:        63.90 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:        2.04, 37.77 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      234.57, 14.63 [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 #28436
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team.
Using 1697 s of XRT Photon Counting mode data and 1 UVOT images for GRB 200917A, 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 = 235.72435, -4.70058 which is equivalent to:
```
RA (J2000): 15h 42m 53.84s
Dec (J2000): -04d 42' 02.1"
```
with an uncertainty of 1.9 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 #28442
V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D.Kuvshinov, D. Cheryasov (Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA),
R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias),
D. Buckley (South African Astronomical Observatory),
O.A. Gres, N.M. Budnev, O.Ershova (Irkutsk State University, API),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
V. Yurkov, A. Gabovich, Yu. Sergienko (Blagoveschensk Educational State University)
MASTER-Tavrida robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, SAI Crimea astronomical station) was pointed to the Swift GRB 200917A ( E. Sonbas et al., GCN 28435) errorbox 46136 sec after notice time and 46245 sec after trigger time at 2020-09-17 16:43:13 UT, with upper limit up to 15.9 mag. Observations started at twilight. The observations began at zenith distance = 64 deg. The sun altitude is -10.4 deg.
The galactic latitude b = 37 deg., longitude l = 2 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1443272
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

   46335 |      MASTER-Tavrida |   C |   180 | 15.9 |        
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
GCN Circular #28444
V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A. Melandri (INAF-OAB) and E. Sonbas report on behalf of the Swift-XRT team:
We have analysed 7.1 ks of XRT data for GRB 200917A (Sonbas et al. GCN Circ. 28435), from 112 s to 34.8 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Goad et al. (GCN Circ. 28436).
The late-time light curve (from T0+5.1 ks) can be modelled with a power-law decay with a decay index of alpha=1.31 (+0.17, -0.16).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.34 (+0.28, -0.26). The best-fitting absorption column is 1.08 (+0.25, -0.22) x 10^22 cm^-2, in excess of the Galactic value of 1.5 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.1 x 10^-11 (1.1 x 10^-10) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     1.08 (+0.25, -0.22) x 10^22 cm^-2
Galactic foreground: 1.5 x 10^21 cm^-2
Excess significance: 7.0 sigma
Photon index:	     2.34 (+0.28, -0.26)
```
If the light curve continues to decay with a power-law decay index of 1.31, the count rate at T+24 hours will be 5.2 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.1 x 10^-13 (5.5 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/00996184.
This circular is an official product of the Swift-XRT team.
GCN Circular #28445
J. Wood (NASA/MSFC) reports on behalf of the Fermi-GBM Team:
Swift-BAT detected GRB 200917A at 03:52:28 UT (Sonbas et al. 2020, GCN 28435). There was no Fermi-GBM onboard trigger around the event. An automated, blind search for short gamma-ray bursts below the onboard triggering threshold in Fermi-GBM also identified no counterparts.
The GBM targeted search [1], the most sensitive, coherent search for GRB-like signals, was run from +/-30 s around BAT trigger time. A transient source was identified whose most significant timescale according to the automated search is 4.096 s, with a log likelihood ratio of 21. This timescale corresponds to the first peak in the lightcurve, occurring -11 seconds before the BAT trigger time. The full light curve consists of multiple peaks spanning from approximately 11 seconds before to 10 seconds after the BAT trigger time.
The location is consistent with that from Swift-BAT. The spectrum is consistent with a "normal" GRB template (Band function with Epeak = 230 keV, alpha = -1.0, beta = -2.3).
[1] Goldstein et al. 2019 arXiv:1903.12597
GCN Circular #28447
C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL), T. Sakamoto (AGU), E. Sonbas (Adiyaman Univ.), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 200917A (trigger #996184) (Sonbas, et al., GCN Circ. 28435). The BAT ground-calculated position is RA, Dec = 235.742, -4.695 deg which is
```
   RA(J2000)  =  15h 42m 58.0s
   Dec(J2000) = -04d 41' 41.4"
```
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 96%.
The mask-weighted light curve shows two peaks, a weak peak at ~T-10 s and a stronger peak at ~T+5 s. T90 (15-350 keV) is 19.4 +- 2.9 sec (estimated error including systematics).
The time-averaged spectrum from T-15.76 to T+6.18 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.24 +- 0.31. The fluence in the 15-150 keV band is 3.0 +- 0.6 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T+5.04 sec in the 15-150 keV band is 0.6 +- 0.2 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/996184/BA/
GCN Circular #28450
H. Kumar (IITB), K. Sharma(IITB), U. Stanzin (IAO), V. Bhalerao(IITB), G. C. Anupama(IIA), S. Barway(IIA), report on behalf of the GROWTH-India collaboration:
We observed GRB 200917A reported by Swift-BAT (E. Sonbas et al., GCN 28435, M.R. Goad et al., GCN 28436) with 0.7m GROWTH-India Telescope (GIT). The field was observed in the SDSS r’ filter starting at 2020-09-17T14:15:12.96 UT i.e. ~10.37 hrs after the event detection by Swift-BAT. We obtained 6 exposures of 300 sec each, at an airmass of ~2.5. We did not find any source in the stacked image within the uncertainty region of 1.9 arcsec around the Swift-XRT position of RA(J2000): 15h 42m 53.84s, Dec(J2000): -04d 42' 02.1" (GCN 28436). We obtained an upper limit of r > 20.23 mag (5-sigma), calibrated against PanSTARRs PS1 data release (Flewelling et al., 2018).
The GROWTH India Telescope (GIT) is a 70-cm telescope with a 0.7-degree field of view, set up by the Indian Institute of Astrophysics and the Indian Institute of Technology Bombay with support from the Indo-US Science and Technology Forum (IUSSTF) and the Science and Engineering Research Board (SERB) of the Department of Science and Technology (DST), Government of India (https://sites.google.com/view/growthindia/). It is located at the Indian Astronomical Observatory (Hanle), operated by the Indian Institute of Astrophysics (IIA).
GCN Circular #28475
GRB 200917A: Swift/UVOT Upper Limits
K. K. Simpson (PSU) and E. Sonbas (Adiyaman Univ.) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 200917A 104 s after the BAT trigger (Sonbas et al., GCN Circ. 28435). No optical afterglow consistent with the XRT position (Goad et al. GCN Circ. 28436) 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           104          254          147         >19.9
u_FC               262          512          246         >20.1
white              104         1708          412         >20.5
v                  592         1758          136         >18.9
b                  518         1684          117         >19.5
u                  262         1832          382         >20.2
w1                 641         1807          136         >18.7
m2                1762         1782           19         >18.2
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.19 in the direction of the burst (Schlegel et al. 1998).

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Jochen Greiner, last update: 22-Sep-2020 [Disclaimer]