Gamma-ray Burst 200901B

(All information courtesy of the instrument teams.)

Previous IAU Circulars

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Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 01 Sep 20 07:11:27 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     994165,   Seg_Num: 0
GRB_RA:          217.879d {+14h 31m 31s} (J2000),
                 218.201d {+14h 32m 48s} (current),
                 217.103d {+14h 28m 25s} (1950)
GRB_DEC:         -38.716d {-38d 42' 58"} (J2000),
                 -38.807d {-38d 48' 24"} (current),
                 -38.495d {-38d 29' 42"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       0 [cnts]    Image_Peak=1890 [image_cnts]
TRIGGER_DUR:     104.000 [sec] 
TRIGGER_INDEX:   20000     E_range: 15-50 keV
BKG_INTEN:       0 [cnts]
BKG_TIME:        0.00 SOD {00:00:00.00} UT
BKG_DUR:         0 [sec]
GRB_DATE:        19093 TJD;   245 DOY;   20/09/01
GRB_TIME:        25766.44 SOD {07:09:26.44} UT
GRB_PHI:          27.15 [deg]
GRB_THETA:        24.28 [deg]
SOLN_STATUS:     0x2013
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    7.77 [sigma]
MERIT_PARAMS:     +1  +0  +0  +7  +1  -2  +0  +0 -33  +0 
SUN_POSTN:       160.89d {+10h 43m 34s}   +8.08d {+08d 04' 34"}
SUN_DIST:         70.81 [deg]   Sun_angle= -3.8 [hr] (East of Sun)
MOON_POSTN:      332.46d {+22h 09m 50s}  -16.12d {-16d 07' 22"}
MOON_DIST:        97.67 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      323.51, 20.12 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      228.18,-22.54 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Coordinates.  
COMMENTS:        This is an image trigger.  (The RATE_SIGNIF & BKG_{INTEN, TIME, DUR} are undefined.)  
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:        There is a bright star (mag=5.97) 10.01 arcmin from this position.  
COMMENTS:        This is a GRB.  
COMMENTS:        This trigger occurred at longitude,latitude = 140.88,5.94 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 01 Sep 20 07:12:41 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     994165,   Seg_Num: 0
GRB_RA:          217.8572d {+14h 31m 25.72s} (J2000),
                 218.1789d {+14h 32m 42.93s} (current),
                 217.0815d {+14h 28m 19.55s} (1950)
GRB_DEC:         -38.7117d {-38d 42' 42.1"} (J2000),
                 -38.8023d {-38d 48' 08.4"} (current),
                 -38.4907d {-38d 29' 26.6"} (1950)
GRB_ERROR:       5.5 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.11e-09 [erg/cm2/sec]
GRB_SIGNIF:      6.55 [sigma]
IMG_START_DATE:  19093 TJD;   245 DOY;   20/09/01
IMG_START_TIME:  25936.13 SOD {07:12:16.13} UT,   169.7 [sec] since BAT Trigger Time
TAM[0-3]:        327.67 237.19 261.64 243.60
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       160.89d {+10h 43m 34s}   +8.08d {+08d 04' 32"}
SUN_DIST:         70.79 [deg]   Sun_angle= -3.8 [hr] (East of Sun)
MOON_POSTN:      332.47d {+22h 09m 53s}  -16.12d {-16d 07' 09"}
MOON_DIST:        97.70 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      323.49, 20.13 [deg] galactic lon,lat of the burst
ECL_COORDS:      228.16,-22.54 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 1.06 arcmin from the BAT position.  
COMMENTS:        There is a bright star (mag=5.97) 9.92 arcmin from the XRT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 01 Sep 20 07:13:57 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     994165,   Seg_Num: 0
GRB_RA:          217.879d {+14h 31m 31s} (J2000),
                 218.201d {+14h 32m 48s} (current),
                 217.103d {+14h 28m 25s} (1950)
GRB_DEC:         -38.716d {-38d 42' 58"} (J2000),
                 -38.807d {-38d 48' 24"} (current),
                 -38.495d {-38d 29' 42"} (1950)
GRB_DATE:        19093 TJD;   245 DOY;   20/09/01
GRB_TIME:        25766.44 SOD {07:09:26.44} UT
TRIGGER_INDEX:   20000
GRB_PHI:          27.15 [deg]
GRB_THETA:        24.28 [deg]
DELTA_TIME:      0.00 [sec]
TRIGGER_DUR:     104.000 [sec] 
SOLN_STATUS:     0x2013
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    7.77 [sigma]
LC_URL:          sw00994165000msb.lc
SUN_POSTN:       160.89d {+10h 43m 34s}   +8.08d {+08d 04' 31"}
SUN_DIST:         70.81 [deg]   Sun_angle= -3.8 [hr] (East of Sun)
MOON_POSTN:      332.48d {+22h 09m 55s}  -16.12d {-16d 06' 57"}
MOON_DIST:        97.69 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      323.51, 20.12 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      228.18,-22.54 [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 an image 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:        There is a bright star (mag=5.97) 10.01 arcmin from this position.  
COMMENTS:        This is a GRB.  
COMMENTS:        This trigger occurred at longitude,latitude = 140.88,5.94 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 01 Sep 20 07:12:51 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     994165,   Seg_Num: 0
GRB_RA:          217.8572d {+14h 31m 25.7s} (J2000),
                 218.1789d {+14h 32m 42.9s} (current),
                 217.0815d {+14h 28m 19.5s} (1950)
GRB_DEC:         -38.7117d {-38d 42' 42.1"} (J2000),
                 -38.8023d {-38d 48' 08.4"} (current),
                 -38.4907d {-38d 29' 26.6"} (1950)
GRB_ERROR:       5.4 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       43 [cnts]
IMG_START_DATE:  19093 TJD;   245 DOY;   20/09/01
IMG_START_TIME:  25936.13 SOD {07:12:16.13} UT,   169.7 [sec] since BAT Trigger Time
CENTROID_X:      302.00,  raw= 302  [pixels]
CENTROID_Y:      288.32,  raw= 288  [pixels]
ROLL:            298.32 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -23.03
GRB_POS_XRT_Z:   -12.72
IMAGE_URL:       sw00994165000msxps_rw.img
SUN_POSTN:       160.89d {+10h 43m 34s}   +8.08d {+08d 04' 32"}
SUN_DIST:         70.79 [deg]   Sun_angle= -3.8 [hr] (East of Sun)
MOON_POSTN:      332.47d {+22h 09m 53s}  -16.12d {-16d 07' 08"}
MOON_DIST:        97.70 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      323.49, 20.13 [deg] galactic lon,lat of the burst
ECL_COORDS:      228.16,-22.54 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.  
COMMENTS:        There is a bright star (mag=5.97) 10.01 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 01 Sep 20 07:12:53 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     994165,   Seg_Num: 0
GRB_RA:          217.8572d {+14h 31m 25.7s} (J2000),
                 218.1789d {+14h 32m 42.9s} (current),
                 217.0815d {+14h 28m 19.5s} (1950)
GRB_DEC:         -38.7117d {-38d 42' 42.1"} (J2000),
                 -38.8023d {-38d 48' 08.4"} (current),
                 -38.4907d {-38d 29' 26.6"} (1950)
GRB_ERROR:       5.4 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       43 [cnts]
IMG_START_DATE:  19093 TJD;   245 DOY;   20/09/01
IMG_START_TIME:  25936.13 SOD {07:12:16.13} UT,   169.7 [sec] since BAT Trigger Time
CENTROID_X:      302.00,  raw= 302  [pixels]
CENTROID_Y:      288.32,  raw= 288  [pixels]
ROLL:            298.32 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -23.03
GRB_POS_XRT_Z:   -12.72
IMAGE_URL:       sw00994165000msxps_rw.img
SUN_POSTN:       160.89d {+10h 43m 34s}   +8.08d {+08d 04' 32"}
SUN_DIST:         70.79 [deg]   Sun_angle= -3.8 [hr] (East of Sun)
MOON_POSTN:      332.47d {+22h 09m 53s}  -16.12d {-16d 07' 07"}
MOON_DIST:        97.70 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      323.49, 20.13 [deg] galactic lon,lat of the burst
ECL_COORDS:      228.16,-22.54 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.  
COMMENTS:        There is a bright star (mag=5.97) 10.01 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 01 Sep 20 07:16:55 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     994165,   Seg_Num: 0
POINT_RA:        217.858d {+14h 31m 26s} (J2000)
POINT_DEC:       -38.718d {-38d 43' 05"} (J2000)
POINT_ROLL:      298.319d
IMG_START_DATE:  19093 TJD;   245 DOY;   20/09/01
IMG_START_TIME:  25941.93 SOD {07:12:21.93} UT,   175.5 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.172
N_STARS:         190
X_OFFSET:        192 [pixels]
Y_OFFSET:        440 [pixels]
X_MAX:           1631 [pixels]
Y_MAX:           1879 [pixels]
DET_THRESH:      9
PHOTO_THRESH:    4
SL_URL:          sw00994165000msufc0175.fits
SUN_POSTN:       160.90d {+10h 43m 35s}   +8.07d {+08d 04' 29"}
SUN_DIST:         70.80 [deg]   Sun_angle= -3.8 [hr] (East of Sun)
MOON_POSTN:      332.51d {+22h 10m 01s}  -16.11d {-16d 06' 28"}
MOON_DIST:        97.73 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      323.49, 20.13 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      228.16,-22.54 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.  
COMMENTS:        There is a bright star (mag=5.97) 10.01 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 01 Sep 20 07:17:12 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     994165,   Seg_Num: 0
POINT_RA:        217.858d {+14h 31m 26s} (J2000)
POINT_DEC:       -38.718d {-38d 43' 05"} (J2000)
POINT_ROLL:      298.319d
IMG_START_DATE:  19093 TJD;   245 DOY;   20/09/01
IMG_START_TIME:  25941.93 SOD {07:12:21.93} UT,   175.5 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.172
N_STARS:         190
X_OFFSET:        192 [pixels]
Y_OFFSET:        440 [pixels]
X_MAX:           1631 [pixels]
Y_MAX:           1879 [pixels]
DET_THRESH:      9
PHOTO_THRESH:    4
SL_URL:          sw00994165000msufc0175.fits
SUN_POSTN:       160.90d {+10h 43m 35s}   +8.07d {+08d 04' 28"}
SUN_DIST:         70.79 [deg]   Sun_angle= -3.8 [hr] (East of Sun)
MOON_POSTN:      332.51d {+22h 10m 02s}  -16.11d {-16d 06' 25"}
MOON_DIST:        97.73 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      323.49, 20.13 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      228.16,-22.54 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.  
COMMENTS:        There is a bright star (mag=5.97) 10.01 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 01 Sep 20 07:18:47 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     994165,   Seg_Num: 0
POINT_RA:        217.858d {+14h 31m 26s} (J2000)
POINT_DEC:       -38.718d {-38d 43' 05"} (J2000)
ROLL:            298.319d
IMG_START_DATE:  19093 TJD;   245 DOY;   20/09/01
IMG_START_TIME:  25941.93 SOD {07:12:21.93} UT,   175.5 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     620637167
X_OFFSET:        842 [pixels]
Y_OFFSET:        920 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1002
Y_GRB_POS:       1080
BINNING_INDEX:   1
IM_URL:          sw00994165000msuni0201.fits
SUN_POSTN:       160.90d {+10h 43m 35s}   +8.07d {+08d 04' 27"}
SUN_DIST:         70.79 [deg]   Sun_angle= -3.8 [hr] (East of Sun)
MOON_POSTN:      332.52d {+22h 10m 05s}  -16.10d {-16d 06' 09"}
MOON_DIST:        97.74 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      323.49, 20.13 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      228.16,-22.54 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        There is a bright star (mag=5.97) 10.01 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 01 Sep 20 07:19:05 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     994165,   Seg_Num: 0
POINT_RA:        217.858d {+14h 31m 26s} (J2000)
POINT_DEC:       -38.718d {-38d 43' 05"} (J2000)
ROLL:            298.319d
IMG_START_DATE:  19093 TJD;   245 DOY;   20/09/01
IMG_START_TIME:  25941.93 SOD {07:12:21.93} UT,   175.5 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     620637167
X_OFFSET:        842 [pixels]
Y_OFFSET:        920 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1002
Y_GRB_POS:       1080
BINNING_INDEX:   1
IM_URL:          sw00994165000msuni0201.fits
SUN_POSTN:       160.90d {+10h 43m 35s}   +8.07d {+08d 04' 27"}
SUN_DIST:         70.79 [deg]   Sun_angle= -3.8 [hr] (East of Sun)
MOON_POSTN:      332.52d {+22h 10m 06s}  -16.10d {-16d 06' 06"}
MOON_DIST:        97.75 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      323.49, 20.13 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      228.16,-22.54 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.  
COMMENTS:        There is a bright star (mag=5.97) 10.01 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 01 Sep 20 07:25:57 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     994165,   Seg_Num: 0
POINT_RA:        217.855d {+14h 31m 25s} (J2000)
POINT_DEC:       -38.721d {-38d 43' 13"} (J2000)
POINT_ROLL:      298.321d
IMG_START_DATE:  19093 TJD;   245 DOY;   20/09/01
IMG_START_TIME:  26621.29 SOD {07:23:41.29} UT,   854.9 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.426
N_STARS:         156
X_OFFSET:        282 [pixels]
Y_OFFSET:        360 [pixels]
X_MAX:           1721 [pixels]
Y_MAX:           1799 [pixels]
DET_THRESH:      6
PHOTO_THRESH:    2
SL_URL:          sw00994165000msufc0854.fits
SUN_POSTN:       160.90d {+10h 43m 36s}   +8.07d {+08d 04' 20"}
SUN_DIST:         70.79 [deg]   Sun_angle= -3.8 [hr] (East of Sun)
MOON_POSTN:      332.58d {+22h 10m 20s}  -16.08d {-16d 04' 59"}
MOON_DIST:        97.80 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      323.49, 20.13 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      228.16,-22.55 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.  
COMMENTS:        There is a bright star (mag=5.97) 10.01 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 01 Sep 20 07:26:13 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     994165,   Seg_Num: 0
POINT_RA:        217.855d {+14h 31m 25s} (J2000)
POINT_DEC:       -38.721d {-38d 43' 13"} (J2000)
POINT_ROLL:      298.321d
IMG_START_DATE:  19093 TJD;   245 DOY;   20/09/01
IMG_START_TIME:  26621.29 SOD {07:23:41.29} UT,   854.9 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.426
N_STARS:         156
X_OFFSET:        282 [pixels]
Y_OFFSET:        360 [pixels]
X_MAX:           1721 [pixels]
Y_MAX:           1799 [pixels]
DET_THRESH:      6
PHOTO_THRESH:    2
SL_URL:          sw00994165000msufc0854.fits
SUN_POSTN:       160.90d {+10h 43m 36s}   +8.07d {+08d 04' 20"}
SUN_DIST:         70.79 [deg]   Sun_angle= -3.8 [hr] (East of Sun)
MOON_POSTN:      332.58d {+22h 10m 20s}  -16.08d {-16d 04' 56"}
MOON_DIST:        97.80 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      323.49, 20.13 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      228.16,-22.55 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.  
COMMENTS:        There is a bright star (mag=5.97) 10.01 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 01 Sep 20 07:27:04 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     994165,   Seg_Num: 0
POINT_RA:        217.855d {+14h 31m 25s} (J2000)
POINT_DEC:       -38.721d {-38d 43' 13"} (J2000)
ROLL:            298.321d
IMG_START_DATE:  19093 TJD;   245 DOY;   20/09/01
IMG_START_TIME:  26621.29 SOD {07:23:41.29} UT,   854.9 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     620637846
X_OFFSET:        841 [pixels]
Y_OFFSET:        919 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1001
Y_GRB_POS:       1079
BINNING_INDEX:   1
IM_URL:          sw00994165000msuni0880.fits
SUN_POSTN:       160.90d {+10h 43m 36s}   +8.07d {+08d 04' 19"}
SUN_DIST:         70.79 [deg]   Sun_angle= -3.8 [hr] (East of Sun)
MOON_POSTN:      332.59d {+22h 10m 22s}  -16.08d {-16d 04' 48"}
MOON_DIST:        97.81 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      323.49, 20.13 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      228.16,-22.55 [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).  
COMMENTS:        There is a bright star (mag=5.97) 10.01 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 01 Sep 20 07:27:18 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     994165,   Seg_Num: 0
POINT_RA:        217.855d {+14h 31m 25s} (J2000)
POINT_DEC:       -38.721d {-38d 43' 13"} (J2000)
ROLL:            298.321d
IMG_START_DATE:  19093 TJD;   245 DOY;   20/09/01
IMG_START_TIME:  26621.29 SOD {07:23:41.29} UT,   854.9 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     620637846
X_OFFSET:        841 [pixels]
Y_OFFSET:        919 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1001
Y_GRB_POS:       1079
BINNING_INDEX:   1
IM_URL:          sw00994165000msuni0880.fits
SUN_POSTN:       160.90d {+10h 43m 36s}   +8.07d {+08d 04' 19"}
SUN_DIST:         70.79 [deg]   Sun_angle= -3.8 [hr] (East of Sun)
MOON_POSTN:      332.59d {+22h 10m 23s}  -16.08d {-16d 04' 45"}
MOON_DIST:        97.81 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      323.49, 20.13 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      228.16,-22.55 [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.  
COMMENTS:        There is a bright star (mag=5.97) 10.01 arcmin from the BAT position.

GCN Circular #28337
B. Sbarufatti (PSU), P. A. Evans (U Leicester), A. Y. Lien (GSFC/UMBC), K. L. Page (U Leicester) and A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift Observatory Team:
At 07:09:26 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 200901B (trigger=994165). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 217.879, -38.716 which is
```
   RA(J2000) = 14h 31m 31s
   Dec(J2000) = -38d 42' 58"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). As is usual with an image trigger, the available BAT light curve shows no significant structure.
The XRT began observing the field at 07:12:16.1 UT, 169.7 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 217.8572, -38.7117 which is equivalent to:
```
   RA(J2000)  = 14h 31m 25.73s
   Dec(J2000) = -38d 42' 42.1"
```
with an uncertainty of 5.5 arcseconds (radius, 90% containment). This location is 63 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy.
The initial flux in the 2.5 s image was 1.11e-09 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 250 seconds with the U filter starting 175 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 19.2 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 18.0 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.09.
Burst Advocate for this burst is B. Sbarufatti (bxs60 AT psu.edu). 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 #28339
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team.
Using 903 s of XRT Photon Counting mode data and 1 UVOT images for GRB 200901B, 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 = 217.85911, -38.71147 which is equivalent to:
```
RA (J2000): 14h 31m 26.19s
Dec (J2000): -38d 42' 41.3"
```
with an uncertainty of 4.2 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 #28343
A. A. Breeveld (UCL-MSSL) and B. Sbarufatti (PSU) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 200901B 176 s after the BAT trigger (Sbarufatti et al., GCN Circ. 28337). A source consistent with the XRT position (Sbarufatti et al. GCN Circ. 28337)is detected in the initial UVOT exposures in the u filter only, but many exposures are smeared, so the magnitudes may not be reliable.
Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

v                  482          801           58        >18.1
b                  431          750           58        >19.1
u                  176          426          245         19.3 � 0.3
w1                 531          851           58        >18.1
m2                 506          826           58        >17.9
w2                 457          776           58        >18.2
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.09 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #28345
M. Stamatikos (OSU), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), B. Sbarufatti (PSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 200901B (trigger #994165) (Sbarufatti et al., GCN Circ. 28337). The BAT ground-calculated position is RA, Dec = 217.860, -38.704 deg which is
```
   RA(J2000)  =  14h 31m 26.5s
   Dec(J2000) = -38d 42' 15.2"
```
with an uncertainty of 3.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 82%.
The mask-weighted light curve shows some weak emission that starts at ~T0 and ends at ~T+900 s. The available event data end at T+963 s, and the burst went out of the BAT FOV soon afterwards (~T+1000 s). T90 (15-350 keV) is 705.94 +- 148.71 sec (estimated error including systematics).
The time-averaged spectrum from T+32.14 to T+901.32 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.95 +- 0.63, and Epeak of 46.7 +- 8.6 keV (chi squared 61.80 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 4.3 +- 0.4 x 10^-6 erg/cm2 and the 1-sec peak flux measured from T+68.62 sec in the 15-150 keV band is 0.4 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.95 +- 0.13 (chi squared 71.14 for 57 d.o.f.). All the quoted errors are at the 90% confidence level.
The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/994165/BA/
GCN Circular #28347
J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-IASFPA), A. Tohuvavohu (U. Toronto), D.N. Burrows (PSU) and B. Sbarufatti report on behalf of the Swift-XRT team:
We have analysed 4.6 ks of XRT data for GRB 200901B (Sbarufatti et al. GCN Circ. 28337), from 11.3 ks to 35.0 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN Circ. 28339).
The light curve can be modelled with a series of power-law decays. The light curve initially rises, with an index alpha=-0.6 (+0.7, -0.9). At T+239 s it breaks to an alpha of 0.54 (+0.08, -0.07) before breaking again at T+950 s to a final decay with index alpha=2.61 (+1.29, -0.12).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.15 (+/-0.05). The best-fitting absorption column is 1.66 (+0.27, -0.26) x 10^21 cm^-2, in excess of the Galactic value of 1.2 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 5.8 x 10^-11 (6.3 x 10^-11) erg cm^-2 count^-1.
A summary of the WT-mode spectrum is thus:
```
Total column:	     1.66 (+0.27, -0.26) x 10^21 cm^-2
Galactic foreground: 1.2 x 10^21 cm^-2
Excess significance: 2.9 sigma
Photon index:	     1.15 (+/-0.05)
```
If the light curve continues to decay with a power-law decay index of 2.61, the count rate at T+24 hours will be 8.7 x 10^-5 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.1 x 10^-15 (5.5 x 10^-15) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00994165.
This circular is an official product of the Swift-XRT team.

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Jochen Greiner, last update: 02-Sep-2020 [Disclaimer]