Gamma-ray Burst 181023A

(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 23 Oct 18 02:05:53 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     868427,   Seg_Num: 0
GRB_RA:          248.329d {+16h 33m 19s} (J2000),
                 248.535d {+16h 34m 08s} (current),
                 247.780d {+16h 31m 07s} (1950)
GRB_DEC:         +19.564d {+19d 33' 51"} (J2000),
                 +19.526d {+19d 31' 32"} (current),
                 +19.668d {+19d 40' 05"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       0 [cnts]    Image_Peak=1680 [image_cnts]
TRIGGER_DUR:     96.000 [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:        18414 TJD;   296 DOY;   18/10/23
GRB_TIME:        7442.20 SOD {02:04:02.20} UT
GRB_PHI:         -25.56 [deg]
GRB_THETA:        40.11 [deg]
SOLN_STATUS:     0x13
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    7.13 [sigma]
MERIT_PARAMS:     +1  +0  +0  +7  +1  -3  +0  +0 -63  +0 
SUN_POSTN:       207.55d {+13h 50m 12s}  -11.34d {-11d 20' 11"}
SUN_DIST:         50.81 [deg]   Sun_angle= -2.7 [hr] (East of Sun)
MOON_POSTN:       11.13d {+00h 44m 32s}   -0.22d {-00d 13' 21"}
MOON_DIST:       120.60 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:       36.95, 38.91 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      242.56, 40.96 [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:        This is a GRB.  
COMMENTS:        This trigger occurred at longitude,latitude = 148.85,-19.85 [deg].

red DSS finding chart ps-file

GCN NOTICE

 
TITLE:           GCN/SWIFT NOTICE 
NOTICE_DATE:     Tue 23 Oct 18 02:07:25 UT 
NOTICE_TYPE:     Swift-XRT Nack-Position 
TRIGGER_NUM:     868427,   Seg_Num: 0 
POINT_RA:        248.303d {+16h 33m 13s} (J2000) 
POINT_DEC:       +19.564d {+19d 33' 51"} (J2000) 
IMG_START_DATE:  18414 TJD;   296 DOY;   18/10/23 
IMG_START_TIME:  7637.88 SOD {02:07:17.88} UT,   195.7 [sec] since BAT Trigger Time 
COUNTS:          6    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:     Tue 23 Oct 18 02:08:44 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     868427,   Seg_Num: 0
GRB_RA:          248.329d {+16h 33m 19s} (J2000),
                 248.535d {+16h 34m 08s} (current),
                 247.780d {+16h 31m 07s} (1950)
GRB_DEC:         +19.564d {+19d 33' 51"} (J2000),
                 +19.526d {+19d 31' 32"} (current),
                 +19.668d {+19d 40' 05"} (1950)
GRB_DATE:        18414 TJD;   296 DOY;   18/10/23
GRB_TIME:        7442.20 SOD {02:04:02.20} UT
TRIGGER_INDEX:   20000
GRB_PHI:         -25.56 [deg]
GRB_THETA:        40.11 [deg]
DELTA_TIME:      0.00 [sec]
TRIGGER_DUR:     96.000 [sec] 
SOLN_STATUS:     0x13
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    7.13 [sigma]
LC_URL:          sw00868427000msb.lc
SUN_POSTN:       207.55d {+13h 50m 12s}  -11.34d {-11d 20' 14"}
SUN_DIST:         50.81 [deg]   Sun_angle= -2.7 [hr] (East of Sun)
MOON_POSTN:       11.16d {+00h 44m 37s}   -0.21d {-00d 12' 48"}
MOON_DIST:       120.62 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:       36.95, 38.91 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      242.56, 40.96 [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:        This is a GRB.  
COMMENTS:        This trigger occurred at longitude,latitude = 148.85,-19.85 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 23 Oct 18 02:10:45 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     868427,   Seg_Num: 0
POINT_RA:        248.303d {+16h 33m 13s} (J2000)
POINT_DEC:       +19.564d {+19d 33' 49"} (J2000)
POINT_ROLL:      235.895d
IMG_START_DATE:  18414 TJD;   296 DOY;   18/10/23
IMG_START_TIME:  7641.79 SOD {02:07:21.79} UT,   199.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.216
N_STARS:         45
X_OFFSET:        309 [pixels]
Y_OFFSET:        548 [pixels]
X_MAX:           1268 [pixels]
Y_MAX:           1507 [pixels]
DET_THRESH:      17
PHOTO_THRESH:    10
SL_URL:          sw00868427000msufc0199.fits
SUN_POSTN:       207.55d {+13h 50m 12s}  -11.34d {-11d 20' 16"}
SUN_DIST:         50.79 [deg]   Sun_angle= -2.7 [hr] (East of Sun)
MOON_POSTN:       11.17d {+00h 44m 41s}   -0.21d {-00d 12' 24"}
MOON_DIST:       120.66 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:       36.93, 38.93 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      242.53, 40.96 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.  
COMMENTS:        There is a bright star (mag=5.90) 9.48 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 23 Oct 18 02:11:07 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     868427,   Seg_Num: 0
POINT_RA:        248.303d {+16h 33m 13s} (J2000)
POINT_DEC:       +19.564d {+19d 33' 49"} (J2000)
POINT_ROLL:      235.895d
IMG_START_DATE:  18414 TJD;   296 DOY;   18/10/23
IMG_START_TIME:  7641.79 SOD {02:07:21.79} UT,   199.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.216
N_STARS:         45
X_OFFSET:        309 [pixels]
Y_OFFSET:        548 [pixels]
X_MAX:           1268 [pixels]
Y_MAX:           1507 [pixels]
DET_THRESH:      17
PHOTO_THRESH:    10
SL_URL:          sw00868427000msufc0199.fits
SUN_POSTN:       207.55d {+13h 50m 12s}  -11.34d {-11d 20' 16"}
SUN_DIST:         50.79 [deg]   Sun_angle= -2.7 [hr] (East of Sun)
MOON_POSTN:       11.18d {+00h 44m 42s}   -0.21d {-00d 12' 20"}
MOON_DIST:       120.66 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:       36.93, 38.93 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      242.53, 40.96 [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=5.90) 9.48 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 23 Oct 18 02:11:48 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     868427,   Seg_Num: 0
GRB_RA:          248.3301d {+16h 33m 19.22s} (J2000),
                 248.5365d {+16h 34m 08.76s} (current),
                 247.7817d {+16h 31m 07.59s} (1950)
GRB_DEC:         +19.5712d {+19d 34' 16.3"} (J2000),
                 +19.5327d {+19d 31' 57.7"} (current),
                 +19.6752d {+19d 40' 30.8"} (1950)
GRB_ERROR:       3.8 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  18414 TJD;   296 DOY;   18/10/23
IMG_START_TIME:  7673.00 SOD {02:07:53.00} UT,   230.8 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       207.55d {+13h 50m 13s}  -11.34d {-11d 20' 17"}
SUN_DIST:         50.81 [deg]   Sun_angle= -2.7 [hr] (East of Sun)
MOON_POSTN:       11.18d {+00h 44m 44s}   -0.20d {-00d 12' 12"}
MOON_DIST:       120.64 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:       36.96, 38.91 [deg] galactic lon,lat of the burst
ECL_COORDS:      242.56, 40.97 [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:     Tue 23 Oct 18 02:13:40 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     868427,   Seg_Num: 0
POINT_RA:        248.303d {+16h 33m 13s} (J2000)
POINT_DEC:       +19.564d {+19d 33' 49"} (J2000)
ROLL:            235.895d
IMG_START_DATE:  18414 TJD;   296 DOY;   18/10/23
IMG_START_TIME:  7641.79 SOD {02:07:21.79} UT,   199.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     561953263
X_OFFSET:        628 [pixels]
Y_OFFSET:        867 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       788
Y_GRB_POS:       1027
BINNING_INDEX:   1
IM_URL:          sw00868427000msuni0221.fits
SUN_POSTN:       207.55d {+13h 50m 13s}  -11.34d {-11d 20' 18"}
SUN_DIST:         50.79 [deg]   Sun_angle= -2.7 [hr] (East of Sun)
MOON_POSTN:       11.20d {+00h 44m 47s}   -0.20d {-00d 11' 51"}
MOON_DIST:       120.67 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:       36.93, 38.93 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      242.53, 40.96 [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:     Tue 23 Oct 18 02:13:49 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     868427,   Seg_Num: 0
POINT_RA:        248.303d {+16h 33m 13s} (J2000)
POINT_DEC:       +19.564d {+19d 33' 49"} (J2000)
ROLL:            235.895d
IMG_START_DATE:  18414 TJD;   296 DOY;   18/10/23
IMG_START_TIME:  7641.79 SOD {02:07:21.79} UT,   199.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     561953263
X_OFFSET:        628 [pixels]
Y_OFFSET:        867 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       788
Y_GRB_POS:       1027
BINNING_INDEX:   1
IM_URL:          sw00868427000msuni0221.fits
SUN_POSTN:       207.55d {+13h 50m 13s}  -11.34d {-11d 20' 18"}
SUN_DIST:         50.79 [deg]   Sun_angle= -2.7 [hr] (East of Sun)
MOON_POSTN:       11.20d {+00h 44m 48s}   -0.20d {-00d 11' 49"}
MOON_DIST:       120.67 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:       36.93, 38.93 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      242.53, 40.96 [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:     Tue 23 Oct 18 02:22:31 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     868427,   Seg_Num: 0
POINT_RA:        248.304d {+16h 33m 13s} (J2000)
POINT_DEC:       +19.563d {+19d 33' 47"} (J2000)
POINT_ROLL:      235.896d
IMG_START_DATE:  18414 TJD;   296 DOY;   18/10/23
IMG_START_TIME:  8322.86 SOD {02:18:42.86} UT,   880.7 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.061
N_STARS:         189
X_OFFSET:        69 [pixels]
Y_OFFSET:        308 [pixels]
X_MAX:           1508 [pixels]
Y_MAX:           1747 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    8
SL_URL:          sw00868427000msufc0880.fits
SUN_POSTN:       207.56d {+13h 50m 14s}  -11.34d {-11d 20' 26"}
SUN_DIST:         50.79 [deg]   Sun_angle= -2.7 [hr] (East of Sun)
MOON_POSTN:       11.27d {+00h 45m 05s}   -0.17d {-00d 10' 08"}
MOON_DIST:       120.73 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:       36.93, 38.93 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      242.53, 40.96 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 23 Oct 18 02:22:52 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     868427,   Seg_Num: 0
POINT_RA:        248.304d {+16h 33m 13s} (J2000)
POINT_DEC:       +19.563d {+19d 33' 47"} (J2000)
POINT_ROLL:      235.896d
IMG_START_DATE:  18414 TJD;   296 DOY;   18/10/23
IMG_START_TIME:  8322.86 SOD {02:18:42.86} UT,   880.7 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.061
N_STARS:         189
X_OFFSET:        69 [pixels]
Y_OFFSET:        308 [pixels]
X_MAX:           1508 [pixels]
Y_MAX:           1747 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    8
SL_URL:          sw00868427000msufc0880.fits
SUN_POSTN:       207.56d {+13h 50m 14s}  -11.34d {-11d 20' 26"}
SUN_DIST:         50.79 [deg]   Sun_angle= -2.7 [hr] (East of Sun)
MOON_POSTN:       11.27d {+00h 45m 06s}   -0.17d {-00d 10' 04"}
MOON_DIST:       120.73 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:       36.93, 38.93 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      242.53, 40.96 [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:     Tue 23 Oct 18 02:23:11 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     868427,   Seg_Num: 0
GRB_RA:          248.3291d {+16h 33m 18.98s} (J2000),
                 248.5355d {+16h 34m 08.52s} (current),
                 247.7806d {+16h 31m 07.35s} (1950)
GRB_DEC:         +19.5700d {+19d 34' 12.0"} (J2000),
                 +19.5315d {+19d 31' 53.4"} (current),
                 +19.6740d {+19d 40' 26.5"} (1950)
GRB_ERROR:       2.1 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  18414 TJD;   296 DOY;   18/10/23
IMG_START_TIME:  7673.00 SOD {02:07:53.00} UT,   230.8 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       207.56d {+13h 50m 14s}  -11.34d {-11d 20' 27"}
SUN_DIST:         50.81 [deg]   Sun_angle= -2.7 [hr] (East of Sun)
MOON_POSTN:       11.28d {+00h 45m 06s}   -0.17d {-00d 10' 01"}
MOON_DIST:       120.71 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:       36.95, 38.91 [deg] galactic lon,lat of the burst
ECL_COORDS:      242.56, 40.97 [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:     Tue 23 Oct 18 02:24:17 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     868427,   Seg_Num: 0
POINT_RA:        248.304d {+16h 33m 13s} (J2000)
POINT_DEC:       +19.563d {+19d 33' 47"} (J2000)
ROLL:            235.896d
IMG_START_DATE:  18414 TJD;   296 DOY;   18/10/23
IMG_START_TIME:  8322.86 SOD {02:18:42.86} UT,   880.7 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     561953944
X_OFFSET:        628 [pixels]
Y_OFFSET:        867 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       788
Y_GRB_POS:       1027
BINNING_INDEX:   1
IM_URL:          sw00868427000msuni0902.fits
SUN_POSTN:       207.56d {+13h 50m 15s}  -11.34d {-11d 20' 27"}
SUN_DIST:         50.79 [deg]   Sun_angle= -2.7 [hr] (East of Sun)
MOON_POSTN:       11.29d {+00h 45m 08s}   -0.16d {-00d 09' 48"}
MOON_DIST:       120.74 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:       36.93, 38.93 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      242.53, 40.96 [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:     Tue 23 Oct 18 02:24:29 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     868427,   Seg_Num: 0
POINT_RA:        248.304d {+16h 33m 13s} (J2000)
POINT_DEC:       +19.563d {+19d 33' 47"} (J2000)
ROLL:            235.896d
IMG_START_DATE:  18414 TJD;   296 DOY;   18/10/23
IMG_START_TIME:  8322.86 SOD {02:18:42.86} UT,   880.7 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     561953944
X_OFFSET:        628 [pixels]
Y_OFFSET:        867 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       788
Y_GRB_POS:       1027
BINNING_INDEX:   1
IM_URL:          sw00868427000msuni0902.fits
SUN_POSTN:       207.56d {+13h 50m 15s}  -11.34d {-11d 20' 28"}
SUN_DIST:         50.79 [deg]   Sun_angle= -2.7 [hr] (East of Sun)
MOON_POSTN:       11.29d {+00h 45m 09s}   -0.16d {-00d 09' 46"}
MOON_DIST:       120.74 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:       36.93, 38.93 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      242.53, 40.96 [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 #23366
F. E. Marshall (NASA/GSFC), A. D'Ai (INAF-IASFPA), V. D'Elia (SSDC), J. A. Kennea (PSU), S. J. LaPorte (PSU), A. Y. Lien (GSFC/UMBC), M. J. Moss (George Washington University) and D. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift Observatory Team:
At 02:04:02 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 181023A (trigger=868427). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 248.329, +19.564 which is
```
   RA(J2000) = 16h 33m 19s
   Dec(J2000) = +19d 33' 51"
```
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 02:07:17.8 UT, 195.7 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 248.32979, 19.57140 which is equivalent to:
```
   RA(J2000)  = 16h 33m 19.15s
   Dec(J2000) = +19d 34' 17.0"
```
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This location is 26 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper.
A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (6.04 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 3.4 (+2.82/-2.40) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 199 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 0.05.
Burst Advocate for this burst is F. E. Marshall (marshall AT milkyway.gsfc.nasa.gov). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.)
GCN Circular #23368
Xuhui Han (NAOC), WeiKang Zheng (UC Berkeley) and Alexei V. Filippenko (UC Berkeley) report on behalf of the KAIT GRB team:
The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at Lick Observatory, responded to Swift GRB 181023A (Marshall et al., GCN 23366) starting at 02:16:07 UT, ~12 minutes after the burst under dusk twilight condition. Observations were performed in the clear (roughly R) filters, and the exposure time was 60s per image. Observations lasted for about 25 minutes before it set beyond KAIT hour agnle limit. We do not detect any optical afterglow candidate within the XRT position error circle (Marshall et al., GCN 23366) neither in single image, nor in the co-add images. The typical limiting magnitude of our single clear image is about 19.0 mag calibrated to the Pan-STARRS1 catalog.
GCN Circular #23369
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team.
Using 1424 s of XRT Photon Counting mode data and 2 UVOT images for GRB 181023A, 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 = 248.32870, +19.57062 which is equivalent to:
```
RA (J2000): 16h 33m 18.89s
Dec (J2000): +19d 34' 14.2"
```
with an uncertainty of 1.7 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 #23373
A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), D.N. Burrows (PSU), A. Tohuvavohu (PSU), S. J. LaPorte (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester) and F.E. Marshall report on behalf of the Swift-XRT team:
We have analysed 10 ks of XRT data for GRB 181023A (Marshall et al. GCN Circ. 23366), from 214 s to 36.1 ks after the BAT trigger. The data comprise 493 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN Circ. 23369).
The late-time light curve (from T0+5.4 ks) can be modelled with a series of power-law decays. The initial decay index is alpha=1.56 (+0.16, -0.18). At T+12.4 ks the decay steepens to an alpha of 3.9 (+2.1, -0.4). The light curve breaks again at T+18.1 ks to a decay with alpha=-1.5 (+0.0, -0.7), before a final break at T+22.9 ks s after which the decay index is 2.9 (+0.9, -0.7).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.79 (+/-0.08). The best-fitting absorption column is 2.3 (+/-0.3) x 10^21 cm^-2, in excess of the Galactic value of 6.0 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 4.1 x 10^-11 (5.2 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     2.3 (+/-0.3) x 10^21 cm^-2
Galactic foreground: 6.0 x 10^20 cm^-2
Excess significance: 9.0 sigma
Photon index:	     1.79 (+/-0.08)
```
If the light curve continues to decay with a power-law decay index of 2.9, the count rate at T+24 hours will be 4.5 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.8 x 10^-13 (2.4 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/00868427.
This circular is an official product of the Swift-XRT team.
GCN Circular #23376
GRB 181023A: Swift/UVOT Upper Limits
S. J. LaPorte (PSU) and F. E. Marshall (NASA/GSFC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 181023A 200 s after the BAT trigger (Marshall et al., GCN Circ. 23366). No optical afterglow consistent with the XRT position (Osborne et al. GCN Circ. 23369) 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           200          350          147         >20.1
white              200         2078          470         >20.8
v                  356         2128          194         >19.4
b                  455         2054          175         >20.3
u                  430         2029          175         >19.6
w1                 406         2005          175         >19.6
m2                 554         1803           78         >19.2
w2                 679         2104          175         >19.2
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.05 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #23377
T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU) (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 181023A (trigger #868427) (Marshall et al., GCN Circ. 23366). The BAT ground-calculated position is RA, Dec = 248.322, 19.581 deg which is
```
  RA(J2000)  =  16h 33m 17.4s
  Dec(J2000) = +19d 34' 51.2"
```
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 53%.
The mask-weighted light curve shows a complex structure with some weak overlapping pulses that starts at ~T-30 s and ends at ~T+40 s. Note that the burst entered the BAT FOV at T-48 s, and hence there might be additional emission beforehand. T90 (15-350 keV) is 58.0 +- 8.8 sec (estimated error including systematics).
The time-averaged spectrum from T-27.62 to T+36.68 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.74 +- 0.24. The fluence in the 15-150 keV band is 1.3 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+32.18 sec in the 15-150 keV band is 1.0 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/868427/BA/

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Jochen Greiner, last update: 25-Oct-2018 [Disclaimer]