Gamma-ray Burst 180402A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 02 Apr 18 09:45:14 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     821103,   Seg_Num: 0
GRB_RA:          251.905d {+16h 47m 37s} (J2000),
                 252.164d {+16h 48m 39s} (current),
                 251.194d {+16h 44m 47s} (1950)
GRB_DEC:         -14.963d {-14d 57' 48"} (J2000),
                 -14.995d {-14d 59' 40"} (current),
                 -14.875d {-14d 52' 30"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       2312 [cnts]    Image_Peak=143 [image_cnts]
TRIGGER_DUR:     0.256 [sec] 
TRIGGER_INDEX:   126     E_range: 50-350 keV
BKG_INTEN:       25924 [cnts]
BKG_TIME:        35083.27 SOD {09:44:43.27} UT
BKG_DUR:         8 [sec]
GRB_DATE:        18210 TJD;    92 DOY;   18/04/02
GRB_TIME:        35099.27 SOD {09:44:59.27} UT
GRB_PHI:          58.40 [deg]
GRB_THETA:        31.95 [deg]
SOLN_STATUS:     0x20000003
RATE_SIGNIF:     50.50 [sigma]
IMAGE_SIGNIF:    9.19 [sigma]
MERIT_PARAMS:     +1  +0  +0  -2  +3  +0  +0  +1 +49  +0 
SUN_POSTN:        11.60d {+00h 46m 24s}   +4.98d {+04d 58' 50"}
SUN_DIST:        119.69 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:      215.34d {+14h 21m 22s}   -8.76d {-08d 45' 28"}
MOON_DIST:        36.52 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:        4.08, 18.94 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      252.39,  7.38 [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 = 288.93,-2.30 [deg].  
COMMENTS:           
COMMENTS:        NOTE: This BAT event is temporally(0.0<100sec) coincident with the FERMI_GBM event (trignum=544355104).

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Mon 02 Apr 18 09:45:23 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      48
TRIGGER_NUM:     544355104
GRB_RA:          320.433d {+21h 21m 44s} (J2000),
                 320.748d {+21h 22m 59s} (current),
                 319.568d {+21h 18m 16s} (1950)
GRB_DEC:         -51.333d {-51d 19' 59"} (J2000),
                 -51.255d {-51d 15' 16"} (current),
                 -51.547d {-51d 32' 47"} (1950)
GRB_ERROR:       7.67 [deg radius, statistical plus systematic]
GRB_INTEN:       723 [cnts/sec]
DATA_SIGNIF:     22.30 [sigma]
INTEG_TIME:      0.256 [sec]
GRB_DATE:        18210 TJD;    92 DOY;   18/04/02
GRB_TIME:        35099.37 SOD {09:44:59.37} UT
GRB_PHI:         240.00 [deg]
GRB_THETA:       155.00 [deg]
DATA_TIME_SCALE: 0.2560 [sec]
HARD_RATIO:      0.17
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      98%  GRB
2nd_MOST_LIKELY:   1%  Generic SGR
DETECTORS:       0,0,0, 0,0,0, 1,0,1, 0,0,0, 0,0,
SUN_POSTN:        11.60d {+00h 46m 24s}   +4.98d {+04d 58' 50"}
SUN_DIST:         70.98 [deg]   Sun_angle= 3.4 [hr] (West of Sun)
MOON_POSTN:      215.34d {+14h 21m 23s}   -8.76d {-08d 45' 30"}
MOON_DIST:        92.61 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:      346.47,-44.04 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      305.48,-33.92 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2018/bn180402406/quicklook/glg_lc_medres34_bn180402406.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 233.72,7.45 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(0.0<100sec) coincident with the SWIFT_BAT event (trignum=821103).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 02 Apr 18 09:46:25 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     821103,   Seg_Num: 0
POINT_RA:        251.918d {+16h 47m 40s} (J2000)
POINT_DEC:       -14.969d {-14d 58' 06"} (J2000)
IMG_START_DATE:  18210 TJD;    92 DOY;   18/04/02
IMG_START_TIME:  35179.20 SOD {09:46:19.20} UT,   79.9 [sec] since BAT Trigger Time
COUNTS:          19    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        2    Max_iter_allowed= 4
ERROR_CODE:      1
COMMENTS:        SWIFT-XRT Nack Position.  
COMMENTS:        No source found in the image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 02 Apr 18 09:49:09 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     821103,   Seg_Num: 0
GRB_RA:          251.905d {+16h 47m 37s} (J2000),
                 252.164d {+16h 48m 39s} (current),
                 251.194d {+16h 44m 47s} (1950)
GRB_DEC:         -14.963d {-14d 57' 48"} (J2000),
                 -14.995d {-14d 59' 40"} (current),
                 -14.875d {-14d 52' 30"} (1950)
GRB_DATE:        18210 TJD;    92 DOY;   18/04/02
GRB_TIME:        35099.27 SOD {09:44:59.27} UT
TRIGGER_INDEX:   126
GRB_PHI:          58.40 [deg]
GRB_THETA:        31.95 [deg]
DELTA_TIME:      0.00 [sec]
TRIGGER_DUR:     0.256 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     50.50 [sigma]
IMAGE_SIGNIF:    9.19 [sigma]
LC_URL:          sw00821103000msb.lc
SUN_POSTN:        11.60d {+00h 46m 24s}   +4.98d {+04d 58' 54"}
SUN_DIST:        119.70 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:      215.38d {+14h 21m 31s}   -8.77d {-08d 46' 09"}
MOON_DIST:        36.49 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:        4.08, 18.94 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      252.39,  7.38 [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 = 288.93,-2.30 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 02 Apr 18 09:50:22 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     821103,   Seg_Num: 0
GRB_RA:          251.9326d {+16h 47m 43.82s} (J2000),
                 252.1923d {+16h 48m 46.15s} (current),
                 251.2217d {+16h 44m 53.20s} (1950)
GRB_DEC:         -14.9699d {-14d 58' 11.6"} (J2000),
                 -15.0012d {-15d 00' 04.2"} (current),
                 -14.8819d {-14d 52' 54.8"} (1950)
GRB_ERROR:       3.7 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  18210 TJD;    92 DOY;   18/04/02
IMG_START_TIME:  35224.00 SOD {09:47:04.00} UT,   124.7 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:        11.60d {+00h 46m 25s}   +4.98d {+04d 58' 55"}
SUN_DIST:        119.67 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:      215.39d {+14h 21m 33s}   -8.77d {-08d 46' 21"}
MOON_DIST:        36.50 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:        4.09, 18.91 [deg] galactic lon,lat of the burst
ECL_COORDS:      252.42,  7.37 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        There is a bright star (mag=6.03) 11.04 arcmin from the XRT position.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.58% < P(seren) < 1.1%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 02 Apr 18 09:51:57 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     821103,   Seg_Num: 0
POINT_RA:        251.919d {+16h 47m 41s} (J2000)
POINT_DEC:       -14.967d {-14d 58' 00"} (J2000)
POINT_ROLL:      92.889d
IMG_START_DATE:  18210 TJD;    92 DOY;   18/04/02
IMG_START_TIME:  35239.18 SOD {09:47:19.18} UT,   139.9 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.102
N_STARS:         63
X_OFFSET:        135 [pixels]
Y_OFFSET:        349 [pixels]
X_MAX:           1574 [pixels]
Y_MAX:           1788 [pixels]
DET_THRESH:      9
PHOTO_THRESH:    4
SL_URL:          sw00821103000msufc0139.fits
SUN_POSTN:        11.60d {+00h 46m 25s}   +4.98d {+04d 58' 56"}
SUN_DIST:        119.68 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:      215.40d {+14h 21m 36s}   -8.78d {-08d 46' 37"}
MOON_DIST:        36.48 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:        4.09, 18.92 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      252.40,  7.37 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.  
COMMENTS:        There is a bright star (mag=6.27) 11.82 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 02 Apr 18 09:52:27 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     821103,   Seg_Num: 0
GRB_RA:          251.9336d {+16h 47m 44.06s} (J2000),
                 252.1933d {+16h 48m 46.39s} (current),
                 251.2227d {+16h 44m 53.44s} (1950)
GRB_DEC:         -14.9677d {-14d 58' 03.7"} (J2000),
                 -14.9990d {-14d 59' 56.3"} (current),
                 -14.8797d {-14d 52' 46.9"} (1950)
GRB_ERROR:       2.2 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  18210 TJD;    92 DOY;   18/04/02
IMG_START_TIME:  35224.00 SOD {09:47:04.00} UT,   124.7 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:        11.60d {+00h 46m 25s}   +4.98d {+04d 58' 57"}
SUN_DIST:        119.67 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:      215.41d {+14h 21m 37s}   -8.78d {-08d 46' 43"}
MOON_DIST:        36.48 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:        4.10, 18.91 [deg] galactic lon,lat of the burst
ECL_COORDS:      252.42,  7.38 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        There is a bright star (mag=6.03) 10.94 arcmin from the XRT position.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        This is an Update Notice -- the RA,Dec values herein supersede the previous XRT_POS Notice.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        This position was enhanced using UVOT field astrometry.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.58% < P(seren) < 1.1%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 02 Apr 18 09:52:17 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     821103,   Seg_Num: 0
POINT_RA:        251.919d {+16h 47m 41s} (J2000)
POINT_DEC:       -14.967d {-14d 58' 00"} (J2000)
POINT_ROLL:      92.889d
IMG_START_DATE:  18210 TJD;    92 DOY;   18/04/02
IMG_START_TIME:  35239.18 SOD {09:47:19.18} UT,   139.9 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.102
N_STARS:         63
X_OFFSET:        135 [pixels]
Y_OFFSET:        349 [pixels]
X_MAX:           1574 [pixels]
Y_MAX:           1788 [pixels]
DET_THRESH:      9
PHOTO_THRESH:    4
SL_URL:          sw00821103000msufc0139.fits
SUN_POSTN:        11.60d {+00h 46m 25s}   +4.98d {+04d 58' 57"}
SUN_DIST:        119.68 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:      215.40d {+14h 21m 37s}   -8.78d {-08d 46' 41"}
MOON_DIST:        36.47 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:        4.09, 18.92 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      252.40,  7.37 [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=6.27) 11.82 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 02 Apr 18 09:54:50 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     821103,   Seg_Num: 0
POINT_RA:        251.919d {+16h 47m 41s} (J2000)
POINT_DEC:       -14.967d {-14d 58' 00"} (J2000)
ROLL:            92.889d
IMG_START_DATE:  18210 TJD;    92 DOY;   18/04/02
IMG_START_TIME:  35239.18 SOD {09:47:19.18} UT,   139.9 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     544355259
X_OFFSET:        694 [pixels]
Y_OFFSET:        908 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       854
Y_GRB_POS:       1068
BINNING_INDEX:   1
IM_URL:          sw00821103000msuni0160.fits
SUN_POSTN:        11.60d {+00h 46m 25s}   +4.98d {+04d 58' 59"}
SUN_DIST:        119.69 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:      215.43d {+14h 21m 42s}   -8.79d {-08d 47' 07"}
MOON_DIST:        36.45 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:        4.09, 18.92 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      252.40,  7.37 [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=6.27) 11.82 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 02 Apr 18 09:55:04 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     821103,   Seg_Num: 0
POINT_RA:        251.919d {+16h 47m 41s} (J2000)
POINT_DEC:       -14.967d {-14d 58' 00"} (J2000)
ROLL:            92.889d
IMG_START_DATE:  18210 TJD;    92 DOY;   18/04/02
IMG_START_TIME:  35239.18 SOD {09:47:19.18} UT,   139.9 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     544355259
X_OFFSET:        694 [pixels]
Y_OFFSET:        908 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       854
Y_GRB_POS:       1068
BINNING_INDEX:   1
IM_URL:          sw00821103000msuni0160.fits
SUN_POSTN:        11.61d {+00h 46m 25s}   +4.98d {+04d 58' 59"}
SUN_DIST:        119.69 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:      215.43d {+14h 21m 43s}   -8.79d {-08d 47' 10"}
MOON_DIST:        36.45 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:        4.09, 18.92 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      252.40,  7.37 [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=6.27) 11.82 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 02 Apr 18 10:04:23 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     821103,   Seg_Num: 0
POINT_RA:        251.919d {+16h 47m 41s} (J2000)
POINT_DEC:       -14.967d {-14d 58' 00"} (J2000)
POINT_ROLL:      92.889d
IMG_START_DATE:  18210 TJD;    92 DOY;   18/04/02
IMG_START_TIME:  35973.05 SOD {09:59:33.05} UT,   873.8 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.944
N_STARS:         22
X_OFFSET:        135 [pixels]
Y_OFFSET:        349 [pixels]
X_MAX:           1574 [pixels]
Y_MAX:           1788 [pixels]
DET_THRESH:      12
PHOTO_THRESH:    6
SL_URL:          sw00821103000msufc0873.fits
SUN_POSTN:        11.61d {+00h 46m 27s}   +4.99d {+04d 59' 08"}
SUN_DIST:        119.69 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:      215.51d {+14h 22m 02s}   -8.81d {-08d 48' 46"}
MOON_DIST:        36.36 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:        4.09, 18.92 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      252.40,  7.37 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.  
COMMENTS:        There is a bright star (mag=6.27) 11.82 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 02 Apr 18 10:04:35 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     821103,   Seg_Num: 0
POINT_RA:        251.919d {+16h 47m 41s} (J2000)
POINT_DEC:       -14.967d {-14d 58' 00"} (J2000)
POINT_ROLL:      92.889d
IMG_START_DATE:  18210 TJD;    92 DOY;   18/04/02
IMG_START_TIME:  35973.05 SOD {09:59:33.05} UT,   873.8 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.944
N_STARS:         22
X_OFFSET:        135 [pixels]
Y_OFFSET:        349 [pixels]
X_MAX:           1574 [pixels]
Y_MAX:           1788 [pixels]
DET_THRESH:      12
PHOTO_THRESH:    6
SL_URL:          sw00821103000msufc0873.fits
SUN_POSTN:        11.61d {+00h 46m 27s}   +4.99d {+04d 59' 09"}
SUN_DIST:        119.69 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:      215.51d {+14h 22m 03s}   -8.81d {-08d 48' 48"}
MOON_DIST:        36.36 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:        4.09, 18.92 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      252.40,  7.37 [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=6.27) 11.82 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 02 Apr 18 10:05:48 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     821103,   Seg_Num: 0
POINT_RA:        251.919d {+16h 47m 41s} (J2000)
POINT_DEC:       -14.967d {-14d 58' 00"} (J2000)
ROLL:            92.889d
IMG_START_DATE:  18210 TJD;    92 DOY;   18/04/02
IMG_START_TIME:  35973.05 SOD {09:59:33.05} UT,   873.8 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     544355993
X_OFFSET:        694 [pixels]
Y_OFFSET:        908 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       854
Y_GRB_POS:       1068
BINNING_INDEX:   1
IM_URL:          sw00821103000msuni0894.fits
SUN_POSTN:        11.61d {+00h 46m 27s}   +4.99d {+04d 59' 10"}
SUN_DIST:        119.69 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:      215.52d {+14h 22m 05s}   -8.82d {-08d 49' 00"}
MOON_DIST:        36.35 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:        4.09, 18.92 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      252.40,  7.37 [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=6.27) 11.82 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 02 Apr 18 10:06:03 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     821103,   Seg_Num: 0
POINT_RA:        251.919d {+16h 47m 41s} (J2000)
POINT_DEC:       -14.967d {-14d 58' 00"} (J2000)
ROLL:            92.889d
IMG_START_DATE:  18210 TJD;    92 DOY;   18/04/02
IMG_START_TIME:  35973.05 SOD {09:59:33.05} UT,   873.8 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     544355993
X_OFFSET:        694 [pixels]
Y_OFFSET:        908 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       854
Y_GRB_POS:       1068
BINNING_INDEX:   1
IM_URL:          sw00821103000msuni0894.fits
SUN_POSTN:        11.61d {+00h 46m 27s}   +4.99d {+04d 59' 10"}
SUN_DIST:        119.69 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:      215.52d {+14h 22m 06s}   -8.82d {-08d 49' 03"}
MOON_DIST:        36.35 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:        4.09, 18.92 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      252.40,  7.37 [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=6.27) 11.82 arcmin from the BAT position.

GCN Circular #22580
A. Y. Lien (GSFC/UMBC), A. P. Beardmore (U Leicester), J.D. Gropp (PSU) and K. L. Page (U Leicester) report on behalf of the Neil Gehrels Swift Observatory Team:
At 09:44:59 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 180402A (trigger=821103). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 251.905, -14.963 which is
```
   RA(J2000) = 16h 47m 37s
   Dec(J2000) = -14d 57' 48"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a short peak with a duration of about 0.3 sec. The peak count rate was ~9000 counts/sec (15-350 keV), at ~0 sec after the trigger. There are some additional variation in the light curve, however, this variation is also consistent with the presence of the currently-active black hole transient MAXI J1820+070 in the FOV. Further analysis of the full downlinked data will be required to determine the cause of the variation.
The XRT began observing the field at 09:46:19.2 UT, 79.9 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source with an enhanced position: RA, Dec 251.9335, -14.9683 which is equivalent to:
```
   RA(J2000)  = 16h 47m 44.05s
   Dec(J2000) = -14d 58' 05.8"
```
with an uncertainty of 2.1 arcseconds (radius, 90% containment). This location is 100 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 consistent with the Galactic value of 2.94 x 10^21 cm^-2 (Willingale et al. 2013).
UVOT took a finding chart exposure of 250 seconds with the U filter starting 139 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers none of the XRT error circle. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18.0 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.77.
Burst Advocate for this burst is A. Y. Lien (amy.y.lien AT 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:     Mon 02 Apr 18 10:59:58 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     821103,   Seg_Num: 0
POINT_RA:        251.882d {+16h 47m 32s} (J2000)
POINT_DEC:       -14.933d {-14d 55' 59"} (J2000)
POINT_ROLL:      92.889d
IMG_START_DATE:  18210 TJD;    92 DOY;   18/04/02
IMG_START_TIME:  39427.47 SOD {10:57:07.47} UT,   4328.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.345
N_STARS:         86
X_OFFSET:        733 [pixels]
Y_OFFSET:        665 [pixels]
X_MAX:           1692 [pixels]
Y_MAX:           1624 [pixels]
DET_THRESH:      15
PHOTO_THRESH:    8
SL_URL:          sw00821103000msufc4328.fits
SUN_POSTN:        11.65d {+00h 46m 35s}   +5.00d {+05d 00' 02"}
SUN_DIST:        119.77 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:      215.99d {+14h 23m 58s}   -8.97d {-08d 58' 17"}
MOON_DIST:        35.82 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:        4.10, 18.97 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      252.36,  7.40 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.  
COMMENTS:        There is a bright star (mag=6.27) 11.82 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 02 Apr 18 11:00:13 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     821103,   Seg_Num: 0
POINT_RA:        251.882d {+16h 47m 32s} (J2000)
POINT_DEC:       -14.933d {-14d 55' 59"} (J2000)
POINT_ROLL:      92.889d
IMG_START_DATE:  18210 TJD;    92 DOY;   18/04/02
IMG_START_TIME:  39427.47 SOD {10:57:07.47} UT,   4328.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.345
N_STARS:         86
X_OFFSET:        733 [pixels]
Y_OFFSET:        665 [pixels]
X_MAX:           1692 [pixels]
Y_MAX:           1624 [pixels]
DET_THRESH:      15
PHOTO_THRESH:    8
SL_URL:          sw00821103000msufc4328.fits
SUN_POSTN:        11.65d {+00h 46m 35s}   +5.00d {+05d 00' 02"}
SUN_DIST:        119.77 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:      216.00d {+14h 23m 59s}   -8.97d {-08d 58' 20"}
MOON_DIST:        35.82 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:        4.10, 18.97 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      252.36,  7.40 [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=6.27) 11.82 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 02 Apr 18 11:01:40 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     821103,   Seg_Num: 0
POINT_RA:        251.882d {+16h 47m 32s} (J2000)
POINT_DEC:       -14.933d {-14d 55' 59"} (J2000)
ROLL:            92.889d
IMG_START_DATE:  18210 TJD;    92 DOY;   18/04/02
IMG_START_TIME:  39427.47 SOD {10:57:07.47} UT,   4328.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     544359448
X_OFFSET:        1052 [pixels]
Y_OFFSET:        984 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1212
Y_GRB_POS:       1144
BINNING_INDEX:   1
IM_URL:          sw00821103000msuni4349.fits
SUN_POSTN:        11.65d {+00h 46m 35s}   +5.00d {+05d 00' 03"}
SUN_DIST:        119.77 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:      216.01d {+14h 24m 02s}   -8.98d {-08d 58' 35"}
MOON_DIST:        35.81 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:        4.10, 18.97 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      252.36,  7.40 [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=6.27) 11.82 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 02 Apr 18 11:01:53 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     821103,   Seg_Num: 0
POINT_RA:        251.882d {+16h 47m 32s} (J2000)
POINT_DEC:       -14.933d {-14d 55' 59"} (J2000)
ROLL:            92.889d
IMG_START_DATE:  18210 TJD;    92 DOY;   18/04/02
IMG_START_TIME:  39427.47 SOD {10:57:07.47} UT,   4328.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     544359448
X_OFFSET:        1052 [pixels]
Y_OFFSET:        984 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1212
Y_GRB_POS:       1144
BINNING_INDEX:   1
IM_URL:          sw00821103000msuni4349.fits
SUN_POSTN:        11.65d {+00h 46m 35s}   +5.00d {+05d 00' 04"}
SUN_DIST:        119.77 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:      216.01d {+14h 24m 02s}   -8.98d {-08d 58' 37"}
MOON_DIST:        35.81 [deg]
MOON_ILLUM:      96 [%]
GAL_COORDS:        4.10, 18.97 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      252.36,  7.40 [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=6.27) 11.82 arcmin from the BAT position.

GCN Circular #22581
C. Guidorzi, R. Martone (U. Ferrara), S. Kobayashi (LJMU), C.G. Mundell (U. Bath), A. Gomboc (U. Nova Gorica), I.A. Steele (LJMU) on behalf of a large collaboration report:
The LCO 1-m unit at McDonald Observatory (Texas) began observing Swift possibly short GRB 180402A (Lien et al. GCN 22580) on April 2, 10:02 UT (17.3 minutes since the GRB) with the SDSS-I filter. Within the XRT error circle we do not detect any uncatalogued optical afterglow down to i'>19.3 mag (5x120 s exposure, at a mid time of 23.7 min post GRB) as calibrated against nearby Pan-STARRS objects.
GCN Circular #22582
Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), Jes=FAs Gonz=E1lez (UNAM), Carlos Rom=E1n-Z=FA=F1iga (UNAM), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.), and Vicki Toy (UMD) report:
We observed the field of GRB 180402A (Lien, et al., GCN 22580) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astron=F3mico Nacional on Sierra San Pedro M=E1rtir from 2018/04 2.41 to 2018/04 2.50 UTC (1.8 minutes to 2.33 hours after the BAT trigger), obtaining a total of 1.76 hours exposure in the r and i bands.
For a source within the Swift-XRT error circle, in comparison with the USNO-B1 catalog, we obtain the following upper limits (3-sigma):
```
  r > 23.3
  i > 23.3
```
These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB.
We thank the staff of the Observatorio Astron=F3mico Nacional in San Pedro M=E1rtir.
GCN Circular #22583
WeiKang Zheng 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 180402A (Lien et al., GCN 22580 starting at 09:47:14 UT, 135 s after the burst. Observations were performed with an automatic sequence in the clear (roughly R), V, and I filters, and the exposure time was 20 s per image. We do not detect any optical afterglow candidate within the XRT position error circle (Lien et al., GCN 22580). The typical limiting magnitude of our single clear image is about 18.5 mag calibrated to the APASS catalog.
GCN Circular #22584
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), 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 180402A (trigger #821103) (Lien et al., GCN Circ. 22580). The BAT ground-calculated position is RA, Dec = 251.923, -14.928 deg which is
```
  RA(J2000)  =  16h 47m 41.6s
  Dec(J2000) = -14d 55' 41.6"
```
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 37%.
The mask-weighted light curve shows a single short pulse that starts at ~T0, peaks at ~0.1 s, and ends at ~0.3 s T90 (15-350 keV) is 0.18 +- 0.03 sec (estimated error including systematics). The ground analysis confirmed that the additional variation seen in the raw light curve are indeed from MAXI J1820+070 (Lien et al., GCN Circ. 22580).
The time-averaged spectrum from T+0.05 to T+0.26 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 0.52 +- 0.30. The fluence in the 15-150 keV band is 1.4 +- 0.2 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T-0.34 sec in the 15-150 keV band is 1.8 +- 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/821103/BA/
GCN Circular #22585
C. Malacaria (NASA-MSFC/USRA) reports on behalf of the Fermi GBM Team:
"At 09:44:59.37 UT on 02 April 2018, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 180402A (trigger 544355104 / 180402406).
The event was also detected by the Swift/BAT (Lien et al. 2018, GCN 22580). The GBM on-ground location is consistent with the Swift position.
The LAT boresight angle is 90 degrees.
The duration (T90) is 0.448 +/- 0.326 s (8-1000 keV). The time-averaged spectrum from T0-0.1 s to T0+0.2 s is best fit by a Band function. The best-fit parameters are: Alpha = 2.23 +/- 2.03, Beta = -1.35 +/- 0.04, Epeak = 123.80 +/- 44.00 keV.
The event fluence (8-1000 keV) in this time interval is (8.69 +/- 0.62)E-07 erg/cm^2. The 1-sec peak photon flux measured starting from T0+0 s in the 10-1000 keV band is 17.5 +/- 1.4 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN Circular #22586
V. D'Elia (ASDC), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), A. Tohuvavohu (PSU), S.L. Gibson (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB) and A.Y. Lien report on behalf of the Swift-XRT team:
We have analysed 5.4 ks of XRT data for GRB 180402A (Lien et al. GCN Circ. 22580), from 83 s to 18.3 ks after the BAT trigger. The data comprise 24 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The best available XRT position (using the promptly downlinked event data, the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue) is RA, Dec = 251.9336, -14.9686 which is equivalent to:
```
RA (J2000): 16 47 44.06
Dec(J2000): -14 58 06.9
```
with an uncertainty of 2.1 arcsec (radius, 90% confidence).
The light curve can be modelled with a power-law decay with a decay index of alpha=1.94 (+/-0.10).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.46 (+0.28, -0.26). The best-fitting absorption column is 4.6 (+2.2, -1.7) x 10^21 cm^-2, consistent with the Galactic value of 2.9 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 5.6 x 10^-11 (7.0 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     4.6 (+2.2, -1.7) x 10^21 cm^-2
Galactic foreground: 2.9 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.46 (+0.28, -0.26)
```
If the light curve continues to decay with a power-law decay index of 1.94, the count rate at T+24 hours will be 1.3 x 10^-5 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 7.3 x 10^-16 (9.1 x 10^-16) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00821103.
This circular is an official product of the Swift-XRT team.
GCN Circular #22587
S.W.K. Emery (UCL-MSSL) and A. Y. Lien (GSFC/UMBC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 180402A 140 s after the BAT trigger (Lien et al., GCN Circ. 22580). No optical afterglow consistent with the XRT position (D'Elia et al., GCN Circ. 22586) 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          4328         4478          147         >20.8
u_FC               140          390          246         >19.7
white             4328         6805          407         >20.6
v                  423         5916          286         >19.2
b                 5101         6736          393         >20.2
u                  140         6531          845         >20.3
w1                4691         6326          393         >20.4
w2                5512         5712          197         >19.6
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.77 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #22588
D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, M. Ulanov, A. Tsvetkova, A. Lysenko, A. Kozlova, and T. Cline on behalf of the Konus-Wind team, report:
The short-duration, hard-spectrum GRB 180402A (Swift-BAT detection: Lien et al., GCN Circ. 22580; Fermi-GBM detection: Malacaria, GCN Circ. 22585) triggered Konus-Wind at T0=35100.353 s UT (09:45:00.353).
The burst light curve shows bright, multi-peaked emission episode, which starts at T0-64 ms and has a total duration of ~180 ms, preceded by a weaker pulse at ~T0-340 ms.
As observed by Konus-Wind, the burst had a fluence of 2.14(-0.33,+0.53)x10^-6 erg/cm2, and a 16-ms peak flux, measured from T0+0.086 s, of 2.03(-0.45,+0.60)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
Since the most intense part of the burst was detected before the trigger, the spectral analysis was performed using the KW 3-channel light curve data.
Modeling the KW 3-channel spectrum of the main episode (from T0-0.064 s to T0+0.116 s) by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) yields alpha = -0.01(-0.43,+0.64), and Ep = 703(-161,+276) keV.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB180402_T35100
All the quoted errors are at the 68% confidence level. All the quoted values are preliminary.
GCN Circular #22600
C. Malacaria (NASA-MSFC/USRA) reports on behalf of the Fermi GBM Team:
"We report the refined spectral analysis of the short-duration GRB 180402A (Swift-BAT detection: Lien et al., GCN Circ. 22580; Fermi-GBM detection: Malacaria, GCN Circ. 22585; Konus-Wind observation: Svinkin, GCN Circ. 22588).
The time-averaged spectrum from T0-0.064 s to T0+0.192 s is well fit by a power-law function with an exponential high-energy cutoff.
The best-fit parameters are: Alpha = -0.36 +/- 0.10, Epeak = 1319 +/- 161 keV. The fluence (10-1000 keV) in this time interval is (1.21 +/- 0.06)E-06 erg/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN Circular #22617
E. Mazaeva (IKI), L. Elenin (KIAM), A. Pozanenko (IKI), A. Volnova (IKI), I. Molotov (KIAM) report on behalf of larger GRB follow-up collaboration:
We observed the field of the Swift short burst GRB 180402A (Lien et al., GCN 22580) with 0.4-m telescope of ISON-NM observatory starting on Apr., 02 (UT) 09:45:39, i.e. 40 seconds after the burst trigger. We obtained 4 unfiltered images of 30 s exposure each. We do not detect any source within XRT error circle (Lien et al., GCN 22580). Upper limits are following.
```
Date      start (Ut)   t-T0         Exp.     UL (3sigma)
                       (mid.,sec)    (s)
2018-04-02 09:45:39   55            1*30     14.5
2018-04-02 09:45:39  133            4*30     15.0
```
The photometry is based on nearby USNO-B1.0 stars (R2 magnitudes).

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Jochen Greiner, last update: 08-Apr-2018 [Disclaimer]