Gamma-ray Burst 180818A

(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:     Sat 18 Aug 18 03:12:36 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     853824,   Seg_Num: 0
GRB_RA:          169.611d {+11h 18m 27s} (J2000),
                 169.829d {+11h 19m 19s} (current),
                 169.028d {+11h 16m 07s} (1950)
GRB_DEC:         -48.344d {-48d 20' 39"} (J2000),
                 -48.446d {-48d 26' 46"} (current),
                 -48.071d {-48d 04' 14"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       6152 [cnts]    Image_Peak=198 [image_cnts]
TRIGGER_DUR:     2.048 [sec] 
TRIGGER_INDEX:   253     E_range: 15-50 keV
BKG_INTEN:       64122 [cnts]
BKG_TIME:        11490.55 SOD {03:11:30.55} UT
BKG_DUR:         24 [sec]
GRB_DATE:        18348 TJD;   230 DOY;   18/08/18
GRB_TIME:        11524.02 SOD {03:12:04.02} UT
GRB_PHI:          80.52 [deg]
GRB_THETA:        15.90 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     8.30 [sigma]
IMAGE_SIGNIF:    7.09 [sigma]
MERIT_PARAMS:     +1  +0  +0  +1  +1  -3  +0  +0 -43  +0 
SUN_POSTN:       147.43d {+09h 49m 43s}  +13.14d {+13d 08' 08"}
SUN_DIST:         64.71 [deg]   Sun_angle= -1.5 [hr] (East of Sun)
MOON_POSTN:      232.05d {+15h 28m 12s}  -13.64d {-13d 38' 19"}
MOON_DIST:        61.52 [deg]
MOON_ILLUM:      48 [%]
GAL_COORDS:      287.39, 11.70 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      195.98,-47.15 [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 = 160.57,11.80 [deg].

red DSS finding chart ps-file

GCN NOTICE

 
TITLE:           GCN/SWIFT NOTICE 
NOTICE_DATE:     Sat 18 Aug 18 03:14:02 UT 
NOTICE_TYPE:     Swift-XRT Image 
TRIGGER_NUM:     853824,   Seg_Num: 0 
GRB_RA:          169.6343d {+11h 18m 32.2s} (J2000), 
                 169.8522d {+11h 19m 24.5s} (current), 
                 169.0514d {+11h 16m 12.3s} (1950) 
GRB_DEC:         -48.3464d {-48d 20' 47.0"} (J2000), 
                 -48.4484d {-48d 26' 54.4"} (current), 
                 -48.0728d {-48d 04' 22.0"} (1950) 
GRB_ERROR:       5.0 [arcsec, radius, statistical plus systematic] 
GRB_INTEN:       55 [cnts] 
IMG_START_DATE:  18348 TJD;   230 DOY;   18/08/18 
IMG_START_TIME:  11598.04 SOD {03:13:18.04} UT,   74.0 [sec] since BAT Trigger Time 
CENTROID_X:      351.86,  raw= 352  [pixels] 
CENTROID_Y:      271.11,  raw= 271  [pixels] 
ROLL:            335.96 [deg] 
GAIN:            1 
MODE:            3, Long Image mode 
WAVEFORM:        134 
EXPO_TIME:       2.50 [sec] 
GRB_POS_XRT_Y:   -64.32 
GRB_POS_XRT_Z:   107.17 
IMAGE_URL:       sw00853824000msxps_rw.img 
SUN_POSTN:       147.43d {+09h 49m 43s}  +13.14d {+13d 08' 07"} 
SUN_DIST:         64.72 [deg]   Sun_angle= -1.5 [hr] (East of Sun)
SUN_POSTN:       147.43d {+09h 49m 43s}  +13.14d {+13d 08' 07"} 
SUN_DIST:         64.72 [deg]   Sun_angle= -1.5 [hr] (East of Sun) 
MOON_POSTN:      232.06d {+15h 28m 15s}  -13.64d {-13d 38' 31"} 
MOON_DIST:        61.51 [deg] 
MOON_ILLUM:      48 [%] 
GAL_COORDS:      287.41, 11.71 [deg] galactic lon,lat of the burst 
ECL_COORDS:      196.00,-47.15 [deg] ecliptic lon,lat of the burst 
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Aug 18 03:13:52 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     853824,   Seg_Num: 0
GRB_RA:          169.6343d {+11h 18m 32.23s} (J2000),
                 169.8522d {+11h 19m 24.52s} (current),
                 169.0514d {+11h 16m 12.33s} (1950)
GRB_DEC:         -48.3464d {-48d 20' 47.0"} (J2000),
                 -48.4484d {-48d 26' 54.4"} (current),
                 -48.0728d {-48d 04' 22.0"} (1950)
GRB_ERROR:       5.4 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.28e-09 [erg/cm2/sec]
GRB_SIGNIF:      7.41 [sigma]
IMG_START_DATE:  18348 TJD;   230 DOY;   18/08/18
IMG_START_TIME:  11598.04 SOD {03:13:18.04} UT,   74.0 [sec] since BAT Trigger Time
TAM[0-3]:        327.65 237.19 261.58 243.56
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       147.43d {+09h 49m 43s}  +13.14d {+13d 08' 07"}
SUN_DIST:         64.72 [deg]   Sun_angle= -1.5 [hr] (East of Sun)
MOON_POSTN:      232.06d {+15h 28m 15s}  -13.64d {-13d 38' 30"}
MOON_DIST:        61.51 [deg]
MOON_ILLUM:      48 [%]
GAL_COORDS:      287.41, 11.71 [deg] galactic lon,lat of the burst
ECL_COORDS:      196.00,-47.15 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 0.93 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Aug 18 03:14:04 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     853824,   Seg_Num: 0
GRB_RA:          169.6343d {+11h 18m 32.2s} (J2000),
                 169.8522d {+11h 19m 24.5s} (current),
                 169.0514d {+11h 16m 12.3s} (1950)
GRB_DEC:         -48.3464d {-48d 20' 47.0"} (J2000),
                 -48.4484d {-48d 26' 54.4"} (current),
                 -48.0728d {-48d 04' 22.0"} (1950)
GRB_ERROR:       5.0 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       55 [cnts]
IMG_START_DATE:  18348 TJD;   230 DOY;   18/08/18
IMG_START_TIME:  11598.04 SOD {03:13:18.04} UT,   74.0 [sec] since BAT Trigger Time
CENTROID_X:      351.86,  raw= 352  [pixels]
CENTROID_Y:      271.11,  raw= 271  [pixels]
ROLL:            335.96 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -64.32
GRB_POS_XRT_Z:   107.17
IMAGE_URL:       sw00853824000msxps_rw.img
SUN_POSTN:       147.43d {+09h 49m 43s}  +13.14d {+13d 08' 07"}
SUN_DIST:         64.72 [deg]   Sun_angle= -1.5 [hr] (East of Sun)
MOON_POSTN:      232.06d {+15h 28m 16s}  -13.64d {-13d 38' 31"}
MOON_DIST:        61.51 [deg]
MOON_ILLUM:      48 [%]
GAL_COORDS:      287.41, 11.71 [deg] galactic lon,lat of the burst
ECL_COORDS:      196.00,-47.15 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Aug 18 03:15:41 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     853824,   Seg_Num: 0
GRB_RA:          169.611d {+11h 18m 27s} (J2000),
                 169.829d {+11h 19m 19s} (current),
                 169.028d {+11h 16m 07s} (1950)
GRB_DEC:         -48.344d {-48d 20' 39"} (J2000),
                 -48.446d {-48d 26' 46"} (current),
                 -48.071d {-48d 04' 14"} (1950)
GRB_DATE:        18348 TJD;   230 DOY;   18/08/18
GRB_TIME:        11524.02 SOD {03:12:04.02} UT
TRIGGER_INDEX:   253
GRB_PHI:          80.52 [deg]
GRB_THETA:        15.90 [deg]
DELTA_TIME:      12.00 [sec]
TRIGGER_DUR:     2.048 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     8.30 [sigma]
IMAGE_SIGNIF:    7.09 [sigma]
LC_URL:          sw00853824000msb.lc
SUN_POSTN:       147.43d {+09h 49m 44s}  +13.13d {+13d 08' 06"}
SUN_DIST:         64.71 [deg]   Sun_angle= -1.5 [hr] (East of Sun)
MOON_POSTN:      232.08d {+15h 28m 19s}  -13.65d {-13d 38' 45"}
MOON_DIST:        61.53 [deg]
MOON_ILLUM:      48 [%]
GAL_COORDS:      287.39, 11.70 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      195.98,-47.15 [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 = 160.57,11.80 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Aug 18 03:17:18 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     853824,   Seg_Num: 0
POINT_RA:        169.592d {+11h 18m 22s} (J2000)
POINT_DEC:       -48.327d {-48d 19' 35"} (J2000)
POINT_ROLL:      335.957d
IMG_START_DATE:  18348 TJD;   230 DOY;   18/08/18
IMG_START_TIME:  11606.66 SOD {03:13:26.66} UT,   82.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.894
N_STARS:         190
X_OFFSET:        344 [pixels]
Y_OFFSET:        672 [pixels]
X_MAX:           1303 [pixels]
Y_MAX:           1631 [pixels]
DET_THRESH:      19
PHOTO_THRESH:    11
SL_URL:          sw00853824000msufc0082.fits
SUN_POSTN:       147.43d {+09h 49m 44s}  +13.13d {+13d 08' 05"}
SUN_DIST:         64.69 [deg]   Sun_angle= -1.5 [hr] (East of Sun)
MOON_POSTN:      232.09d {+15h 28m 22s}  -13.65d {-13d 39' 00"}
MOON_DIST:        61.55 [deg]
MOON_ILLUM:      48 [%]
GAL_COORDS:      287.37, 11.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      195.95,-47.15 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Aug 18 03:17:32 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     853824,   Seg_Num: 0
POINT_RA:        169.592d {+11h 18m 22s} (J2000)
POINT_DEC:       -48.327d {-48d 19' 35"} (J2000)
POINT_ROLL:      335.957d
IMG_START_DATE:  18348 TJD;   230 DOY;   18/08/18
IMG_START_TIME:  11606.66 SOD {03:13:26.66} UT,   82.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.894
N_STARS:         190
X_OFFSET:        344 [pixels]
Y_OFFSET:        672 [pixels]
X_MAX:           1303 [pixels]
Y_MAX:           1631 [pixels]
DET_THRESH:      19
PHOTO_THRESH:    11
SL_URL:          sw00853824000msufc0082.fits
SUN_POSTN:       147.43d {+09h 49m 44s}  +13.13d {+13d 08' 04"}
SUN_DIST:         64.69 [deg]   Sun_angle= -1.5 [hr] (East of Sun)
MOON_POSTN:      232.09d {+15h 28m 23s}  -13.65d {-13d 39' 01"}
MOON_DIST:        61.55 [deg]
MOON_ILLUM:      48 [%]
GAL_COORDS:      287.37, 11.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      195.95,-47.15 [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:     Sat 18 Aug 18 03:18:48 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     853824,   Seg_Num: 0
POINT_RA:        169.592d {+11h 18m 22s} (J2000)
POINT_DEC:       -48.327d {-48d 19' 35"} (J2000)
ROLL:            335.957d
IMG_START_DATE:  18348 TJD;   230 DOY;   18/08/18
IMG_START_TIME:  11606.66 SOD {03:13:26.66} UT,   82.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     556254828
X_OFFSET:        660 [pixels]
Y_OFFSET:        1102 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       820
Y_GRB_POS:       1262
BINNING_INDEX:   1
IM_URL:          sw00853824000msuni0104.fits
SUN_POSTN:       147.43d {+09h 49m 44s}  +13.13d {+13d 08' 03"}
SUN_DIST:         64.69 [deg]   Sun_angle= -1.5 [hr] (East of Sun)
MOON_POSTN:      232.11d {+15h 28m 25s}  -13.65d {-13d 39' 12"}
MOON_DIST:        61.55 [deg]
MOON_ILLUM:      48 [%]
GAL_COORDS:      287.37, 11.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      195.95,-47.15 [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).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Aug 18 03:19:02 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     853824,   Seg_Num: 0
POINT_RA:        169.592d {+11h 18m 22s} (J2000)
POINT_DEC:       -48.327d {-48d 19' 35"} (J2000)
ROLL:            335.957d
IMG_START_DATE:  18348 TJD;   230 DOY;   18/08/18
IMG_START_TIME:  11606.66 SOD {03:13:26.66} UT,   82.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     556254828
X_OFFSET:        660 [pixels]
Y_OFFSET:        1102 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       820
Y_GRB_POS:       1262
BINNING_INDEX:   1
IM_URL:          sw00853824000msuni0104.fits
SUN_POSTN:       147.43d {+09h 49m 44s}  +13.13d {+13d 08' 03"}
SUN_DIST:         64.69 [deg]   Sun_angle= -1.5 [hr] (East of Sun)
MOON_POSTN:      232.11d {+15h 28m 26s}  -13.65d {-13d 39' 14"}
MOON_DIST:        61.55 [deg]
MOON_ILLUM:      48 [%]
GAL_COORDS:      287.37, 11.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      195.95,-47.15 [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.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Aug 18 03:23:53 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     853824,   Seg_Num: 0
POINT_RA:        169.589d {+11h 18m 21s} (J2000)
POINT_DEC:       -48.325d {-48d 19' 30"} (J2000)
POINT_ROLL:      335.958d
IMG_START_DATE:  18348 TJD;   230 DOY;   18/08/18
IMG_START_TIME:  11764.67 SOD {03:16:04.67} UT,   240.6 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.624
N_STARS:         190
X_OFFSET:        100 [pixels]
Y_OFFSET:        542 [pixels]
X_MAX:           1539 [pixels]
Y_MAX:           1981 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw00853824000msufc0240.fits
SUN_POSTN:       147.44d {+09h 49m 45s}  +13.13d {+13d 07' 59"}
SUN_DIST:         64.68 [deg]   Sun_angle= -1.5 [hr] (East of Sun)
MOON_POSTN:      232.15d {+15h 28m 36s}  -13.67d {-13d 39' 55"}
MOON_DIST:        61.57 [deg]
MOON_ILLUM:      48 [%]
GAL_COORDS:      287.37, 11.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      195.95,-47.15 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Aug 18 03:24:22 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     853824,   Seg_Num: 0
POINT_RA:        169.589d {+11h 18m 21s} (J2000)
POINT_DEC:       -48.325d {-48d 19' 30"} (J2000)
POINT_ROLL:      335.958d
IMG_START_DATE:  18348 TJD;   230 DOY;   18/08/18
IMG_START_TIME:  11764.67 SOD {03:16:04.67} UT,   240.6 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.624
N_STARS:         190
X_OFFSET:        100 [pixels]
Y_OFFSET:        542 [pixels]
X_MAX:           1539 [pixels]
Y_MAX:           1981 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw00853824000msufc0240.fits
SUN_POSTN:       147.44d {+09h 49m 45s}  +13.13d {+13d 07' 59"}
SUN_DIST:         64.68 [deg]   Sun_angle= -1.5 [hr] (East of Sun)
MOON_POSTN:      232.15d {+15h 28m 37s}  -13.67d {-13d 40' 00"}
MOON_DIST:        61.57 [deg]
MOON_ILLUM:      48 [%]
GAL_COORDS:      287.37, 11.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      195.95,-47.15 [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:     Sat 18 Aug 18 03:25:18 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     853824,   Seg_Num: 0
POINT_RA:        169.589d {+11h 18m 21s} (J2000)
POINT_DEC:       -48.325d {-48d 19' 30"} (J2000)
ROLL:            335.958d
IMG_START_DATE:  18348 TJD;   230 DOY;   18/08/18
IMG_START_TIME:  11764.67 SOD {03:16:04.67} UT,   240.6 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     556254986
X_OFFSET:        660 [pixels]
Y_OFFSET:        1102 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       820
Y_GRB_POS:       1262
BINNING_INDEX:   1
IM_URL:          sw00853824000msuni0262.fits
SUN_POSTN:       147.44d {+09h 49m 45s}  +13.13d {+13d 07' 58"}
SUN_DIST:         64.68 [deg]   Sun_angle= -1.5 [hr] (East of Sun)
MOON_POSTN:      232.16d {+15h 28m 39s}  -13.67d {-13d 40' 07"}
MOON_DIST:        61.58 [deg]
MOON_ILLUM:      48 [%]
GAL_COORDS:      287.37, 11.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      195.95,-47.15 [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:     Sat 18 Aug 18 03:24:31 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     853824,   Seg_Num: 0
GRB_RA:          169.6364d {+11h 18m 32.73s} (J2000),
                 169.8543d {+11h 19m 25.02s} (current),
                 169.0535d {+11h 16m 12.83s} (1950)
GRB_DEC:         -48.3444d {-48d 20' 39.8"} (J2000),
                 -48.4464d {-48d 26' 47.2"} (current),
                 -48.0708d {-48d 04' 14.8"} (1950)
GRB_ERROR:       2.4 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  18348 TJD;   230 DOY;   18/08/18
IMG_START_TIME:  11633.00 SOD {03:13:53.00} UT,   109.0 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       147.44d {+09h 49m 45s}  +13.13d {+13d 07' 59"}
SUN_DIST:         64.71 [deg]   Sun_angle= -1.5 [hr] (East of Sun)
MOON_POSTN:      232.16d {+15h 28m 37s}  -13.67d {-13d 40' 01"}
MOON_DIST:        61.55 [deg]
MOON_ILLUM:      48 [%]
GAL_COORDS:      287.41, 11.71 [deg] galactic lon,lat of the burst
ECL_COORDS:      196.00,-47.14 [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:     Sat 18 Aug 18 03:25:36 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     853824,   Seg_Num: 0
POINT_RA:        169.589d {+11h 18m 21s} (J2000)
POINT_DEC:       -48.325d {-48d 19' 30"} (J2000)
ROLL:            335.958d
IMG_START_DATE:  18348 TJD;   230 DOY;   18/08/18
IMG_START_TIME:  11764.67 SOD {03:16:04.67} UT,   240.6 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     556254986
X_OFFSET:        660 [pixels]
Y_OFFSET:        1102 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       820
Y_GRB_POS:       1262
BINNING_INDEX:   1
IM_URL:          sw00853824000msuni0262.fits
SUN_POSTN:       147.44d {+09h 49m 45s}  +13.13d {+13d 07' 58"}
SUN_DIST:         64.68 [deg]   Sun_angle= -1.5 [hr] (East of Sun)
MOON_POSTN:      232.16d {+15h 28m 40s}  -13.67d {-13d 40' 10"}
MOON_DIST:        61.58 [deg]
MOON_ILLUM:      48 [%]
GAL_COORDS:      287.37, 11.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      195.95,-47.15 [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 #23146
F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team:
At 03:12:04 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 180818A (trigger=853824). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 169.611, -48.344 which is
```
   RA(J2000) = 11h 18m 27s
   Dec(J2000) = -48d 20' 39"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single-peaked structure with a duration of about 10 sec. The peak count rate was ~800 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 03:13:18.0 UT, 74.0 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source with an enhanced position: RA, Dec 169.6364, -48.3444 which is equivalent to:
```
   RA(J2000)  = 11h 18m 32.73s
   Dec(J2000) = -48d 20' 39.7"
```
with an uncertainty of 2.4 arcseconds (radius, 90% containment). This location is 60 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 (1.14 x 10^21 cm^-2, Willingale et al. 2013), with an excess column of 8.5 (+7.18/-5.58) x 10^21 cm^-2 (90% confidence).
The initial flux in the 2.5 s image was 1.28e-09 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 82 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 0.11.
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 NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Aug 18 03:31:49 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     853824,   Seg_Num: 0
POINT_RA:        169.589d {+11h 18m 21s} (J2000)
POINT_DEC:       -48.325d {-48d 19' 30"} (J2000)
POINT_ROLL:      335.959d
IMG_START_DATE:  18348 TJD;   230 DOY;   18/08/18
IMG_START_TIME:  12391.86 SOD {03:26:31.86} UT,   867.8 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.567
N_STARS:         190
X_OFFSET:        100 [pixels]
Y_OFFSET:        542 [pixels]
X_MAX:           1539 [pixels]
Y_MAX:           1981 [pixels]
DET_THRESH:      16
PHOTO_THRESH:    9
SL_URL:          sw00853824000msufc0867.fits
SUN_POSTN:       147.44d {+09h 49m 46s}  +13.13d {+13d 07' 53"}
SUN_DIST:         64.68 [deg]   Sun_angle= -1.5 [hr] (East of Sun)
MOON_POSTN:      232.22d {+15h 28m 53s}  -13.68d {-13d 41' 03"}
MOON_DIST:        61.60 [deg]
MOON_ILLUM:      48 [%]
GAL_COORDS:      287.37, 11.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      195.95,-47.15 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Aug 18 03:32:17 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     853824,   Seg_Num: 0
POINT_RA:        169.589d {+11h 18m 21s} (J2000)
POINT_DEC:       -48.325d {-48d 19' 30"} (J2000)
POINT_ROLL:      335.959d
IMG_START_DATE:  18348 TJD;   230 DOY;   18/08/18
IMG_START_TIME:  12391.86 SOD {03:26:31.86} UT,   867.8 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.567
N_STARS:         190
X_OFFSET:        100 [pixels]
Y_OFFSET:        542 [pixels]
X_MAX:           1539 [pixels]
Y_MAX:           1981 [pixels]
DET_THRESH:      16
PHOTO_THRESH:    9
SL_URL:          sw00853824000msufc0867.fits
SUN_POSTN:       147.44d {+09h 49m 46s}  +13.13d {+13d 07' 53"}
SUN_DIST:         64.68 [deg]   Sun_angle= -1.5 [hr] (East of Sun)
MOON_POSTN:      232.22d {+15h 28m 53s}  -13.69d {-13d 41' 07"}
MOON_DIST:        61.61 [deg]
MOON_ILLUM:      48 [%]
GAL_COORDS:      287.37, 11.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      195.95,-47.15 [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:     Sat 18 Aug 18 03:33:41 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     853824,   Seg_Num: 0
POINT_RA:        169.589d {+11h 18m 21s} (J2000)
POINT_DEC:       -48.325d {-48d 19' 30"} (J2000)
ROLL:            335.959d
IMG_START_DATE:  18348 TJD;   230 DOY;   18/08/18
IMG_START_TIME:  12391.86 SOD {03:26:31.86} UT,   867.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     556255613
X_OFFSET:        660 [pixels]
Y_OFFSET:        1102 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       820
Y_GRB_POS:       1262
BINNING_INDEX:   1
IM_URL:          sw00853824000msuni0889.fits
SUN_POSTN:       147.44d {+09h 49m 47s}  +13.13d {+13d 07' 51"}
SUN_DIST:         64.68 [deg]   Sun_angle= -1.5 [hr] (East of Sun)
MOON_POSTN:      232.24d {+15h 28m 56s}  -13.69d {-13d 41' 19"}
MOON_DIST:        61.61 [deg]
MOON_ILLUM:      48 [%]
GAL_COORDS:      287.37, 11.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      195.95,-47.15 [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:     Sat 18 Aug 18 03:33:49 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     853824,   Seg_Num: 0
POINT_RA:        169.589d {+11h 18m 21s} (J2000)
POINT_DEC:       -48.325d {-48d 19' 30"} (J2000)
ROLL:            335.959d
IMG_START_DATE:  18348 TJD;   230 DOY;   18/08/18
IMG_START_TIME:  12391.86 SOD {03:26:31.86} UT,   867.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     556255613
X_OFFSET:        660 [pixels]
Y_OFFSET:        1102 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       820
Y_GRB_POS:       1262
BINNING_INDEX:   1
IM_URL:          sw00853824000msuni0889.fits
SUN_POSTN:       147.44d {+09h 49m 47s}  +13.13d {+13d 07' 51"}
SUN_DIST:         64.68 [deg]   Sun_angle= -1.5 [hr] (East of Sun)
MOON_POSTN:      232.24d {+15h 28m 57s}  -13.69d {-13d 41' 20"}
MOON_DIST:        61.61 [deg]
MOON_ILLUM:      48 [%]
GAL_COORDS:      287.37, 11.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      195.95,-47.15 [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 #23147
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team.
Using 1503 s of XRT Photon Counting mode data and 1 UVOT images for GRB 180818A, 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 = 169.63679, -48.34440 which is equivalent to:
```
RA (J2000): 11h 18m 32.83s
Dec (J2000): -48d 20' 39.9"
```
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 #23148
V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), A. Melandri (INAF-OAB) and F.E. Marshall report on behalf of the Swift-XRT team:
We have analysed 6.9 ks of XRT data for GRB 180818A (Marshall et al. GCN Circ. 23146), from 80 s to 17.2 ks after the BAT trigger. The data comprise 587 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. 23147).
The light curve can be modelled with an initial power-law decay with an index of alpha=6.0 (+0.8, -0.6), followed by a break at T+172 s to an alpha of 0.63 (+/-0.10).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.8 (+0.5, -0.4). The best-fitting absorption column is 8.9 (+3.1, -2.6) x 10^21 cm^-2, in excess of the Galactic value of 1.1 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 3.2 x 10^-11 (1.2 x 10^-10) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     8.9 (+3.1, -2.6) x 10^21 cm^-2
Galactic foreground: 1.1 x 10^21 cm^-2
Excess significance: 4.9 sigma
Photon index:	     2.8 (+0.5, -0.4)
```
If the light curve continues to decay with a power-law decay index of 0.63, 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 1.4 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/00853824.
This circular is an official product of the Swift-XRT team.
GCN Circular #23150
N. P. M. Kuin (UCL-MSSL) 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 180818A 83 s after the BAT trigger (Marshall et al., GCN Circ. 23146). No optical afterglow consistent with the XRT position (Osborne et al. GCN Circ. 23147) 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            83          232          147         >20.7
u_FC               241          490          246         >20.1
white               83         7151          785         >21.9
v                  570        11683         1198         >19.8
b                  496         6946          510         >20.8
u                  241        17153         1326         >20.9
w1                 621        13097          985         >20.1
m2                 596        12588         1199         >20.5
w2                 546         7357          510         >20.7
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.11 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #23154
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), 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 180818A (trigger #853824) (Marshall et al., GCN Circ. 23146). The BAT ground-calculated position is RA, Dec = 169.698, -48.344 deg which is
```
  RA(J2000)  =  11h 18m 47.5s
  Dec(J2000) = -48d 20' 37.9"
```
with an uncertainty of 2.3 arcmin, (radius, sys+stat, 90% containment). The partial coding was 78%.
The mask-weighted light curve shows a single-pulsed structure that starts at ~T-2 s, peaks at ~T+2 s, and ends at ~T+14 s. T90 (15-350 keV) is 13.7 +- 4.1 sec (estimated error including systematics).
The time-averaged spectrum from T-2.14 to T+14.10 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.15 +- 0.36. The fluence in the 15-150 keV band is 2.6 +- 0.6 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+1.64 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/853824/BA/

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Jochen Greiner, last update: 19-Aug-2018 [Disclaimer]