Gamma-ray Burst 180331A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 31 Mar 18 04:15:49 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     820347,   Seg_Num: 0
GRB_RA:           66.017d {+04h 24m 04s} (J2000),
                  66.273d {+04h 25m 06s} (current),
                  65.316d {+04h 21m 16s} (1950)
GRB_DEC:         +13.398d {+13d 23' 52"} (J2000),
                 +13.439d {+13d 26' 20"} (current),
                 +13.283d {+13d 16' 59"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       31097 [cnts]    Image_Peak=593 [image_cnts]
TRIGGER_DUR:     8.192 [sec] 
TRIGGER_INDEX:   477     E_range: 25-100 keV
BKG_INTEN:       223013 [cnts]
BKG_TIME:        15203.29 SOD {04:13:23.29} UT
BKG_DUR:         64 [sec]
GRB_DATE:        18208 TJD;    90 DOY;   18/03/31
GRB_TIME:        15295.70 SOD {04:14:55.70} UT
GRB_PHI:         -141.13 [deg]
GRB_THETA:        24.62 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     10.90 [sigma]
IMAGE_SIGNIF:    8.89 [sigma]
MERIT_PARAMS:     +1  +0  +0  +3  +2  -1  +0  +0 -55  +0 
SUN_POSTN:         9.57d {+00h 38m 16s}   +4.12d {+04d 07' 14"}
SUN_DIST:         56.69 [deg]   Sun_angle= -3.8 [hr] (East of Sun)
MOON_POSTN:      187.18d {+12h 28m 42s}   +1.36d {+01d 21' 40"}
MOON_DIST:       119.60 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      181.69,-24.42 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       66.46, -8.10 [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 = 173.42,14.00 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 31 Mar 18 04:17:01 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     820347,   Seg_Num: 0
POINT_RA:         66.034d {+04h 24m 08s} (J2000)
POINT_DEC:       +13.398d {+13d 23' 53"} (J2000)
IMG_START_DATE:  18208 TJD;    90 DOY;   18/03/31
IMG_START_TIME:  15408.00 SOD {04:16:48.00} UT,   112.3 [sec] since BAT Trigger Time
COUNTS:          16    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:     Sat 31 Mar 18 04:18:30 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     820347,   Seg_Num: 0
GRB_RA:           66.017d {+04h 24m 04s} (J2000),
                  66.273d {+04h 25m 06s} (current),
                  65.316d {+04h 21m 16s} (1950)
GRB_DEC:         +13.398d {+13d 23' 52"} (J2000),
                 +13.439d {+13d 26' 20"} (current),
                 +13.283d {+13d 16' 59"} (1950)
GRB_DATE:        18208 TJD;    90 DOY;   18/03/31
GRB_TIME:        15295.70 SOD {04:14:55.70} UT
TRIGGER_INDEX:   477
GRB_PHI:         -141.13 [deg]
GRB_THETA:        24.62 [deg]
DELTA_TIME:      38.00 [sec]
TRIGGER_DUR:     8.192 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     10.90 [sigma]
IMAGE_SIGNIF:    8.89 [sigma]
LC_URL:          sw00820347000msb.lc
SUN_POSTN:         9.57d {+00h 38m 17s}   +4.12d {+04d 07' 16"}
SUN_DIST:         56.68 [deg]   Sun_angle= -3.8 [hr] (East of Sun)
MOON_POSTN:      187.20d {+12h 28m 48s}   +1.35d {+01d 21' 08"}
MOON_DIST:       119.62 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      181.69,-24.42 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       66.46, -8.10 [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 = 173.42,14.00 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 31 Mar 18 04:20:50 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     820347,   Seg_Num: 0
POINT_RA:         66.033d {+04h 24m 08s} (J2000)
POINT_DEC:       +13.398d {+13d 23' 54"} (J2000)
POINT_ROLL:      266.037d
IMG_START_DATE:  18208 TJD;    90 DOY;   18/03/31
IMG_START_TIME:  15411.46 SOD {04:16:51.46} UT,   115.8 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        5.597
N_STARS:         19
X_OFFSET:        588 [pixels]
Y_OFFSET:        477 [pixels]
X_MAX:           1547 [pixels]
Y_MAX:           1436 [pixels]
DET_THRESH:      20
PHOTO_THRESH:    12
SL_URL:          sw00820347000msufc0115.fits
SUN_POSTN:         9.57d {+00h 38m 17s}   +4.12d {+04d 07' 19"}
SUN_DIST:         56.70 [deg]   Sun_angle= -3.8 [hr] (East of Sun)
MOON_POSTN:      187.22d {+12h 28m 53s}   +1.34d {+01d 20' 40"}
MOON_DIST:       119.63 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      181.70,-24.41 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       66.48, -8.11 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 31 Mar 18 04:21:00 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     820347,   Seg_Num: 0
POINT_RA:         66.033d {+04h 24m 08s} (J2000)
POINT_DEC:       +13.398d {+13d 23' 54"} (J2000)
POINT_ROLL:      266.037d
IMG_START_DATE:  18208 TJD;    90 DOY;   18/03/31
IMG_START_TIME:  15411.46 SOD {04:16:51.46} UT,   115.8 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        5.597
N_STARS:         19
X_OFFSET:        588 [pixels]
Y_OFFSET:        477 [pixels]
X_MAX:           1547 [pixels]
Y_MAX:           1436 [pixels]
DET_THRESH:      20
PHOTO_THRESH:    12
SL_URL:          sw00820347000msufc0115.fits
SUN_POSTN:         9.57d {+00h 38m 17s}   +4.12d {+04d 07' 19"}
SUN_DIST:         56.70 [deg]   Sun_angle= -3.8 [hr] (East of Sun)
MOON_POSTN:      187.22d {+12h 28m 53s}   +1.34d {+01d 20' 38"}
MOON_DIST:       119.63 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      181.70,-24.41 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       66.48, -8.11 [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 31 Mar 18 04:21:20 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     820347,   Seg_Num: 0
GRB_RA:           66.0246d {+04h 24m 05.90s} (J2000),
                  66.2805d {+04h 25m 07.32s} (current),
                  65.3239d {+04h 21m 17.73s} (1950)
GRB_DEC:         +13.3990d {+13d 23' 56.3"} (J2000),
                 +13.4401d {+13d 26' 24.2"} (current),
                 +13.2843d {+13d 17' 03.5"} (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:  18208 TJD;    90 DOY;   18/03/31
IMG_START_TIME:  15499.00 SOD {04:18:19.00} UT,   203.3 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:         9.57d {+00h 38m 17s}   +4.12d {+04d 07' 19"}
SUN_DIST:         56.69 [deg]   Sun_angle= -3.8 [hr] (East of Sun)
MOON_POSTN:      187.23d {+12h 28m 54s}   +1.34d {+01d 20' 34"}
MOON_DIST:       119.64 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      181.70,-24.42 [deg] galactic lon,lat of the burst
ECL_COORDS:       66.47, -8.10 [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:     Sat 31 Mar 18 04:22:58 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     820347,   Seg_Num: 0
POINT_RA:         66.033d {+04h 24m 08s} (J2000)
POINT_DEC:       +13.398d {+13d 23' 54"} (J2000)
ROLL:            266.037d
IMG_START_DATE:  18208 TJD;    90 DOY;   18/03/31
IMG_START_TIME:  15411.46 SOD {04:16:51.46} UT,   115.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     544162632
X_OFFSET:        907 [pixels]
Y_OFFSET:        796 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1067
Y_GRB_POS:       956
BINNING_INDEX:   1
IM_URL:          sw00820347000msuni0136.fits
SUN_POSTN:         9.57d {+00h 38m 17s}   +4.12d {+04d 07' 21"}
SUN_DIST:         56.70 [deg]   Sun_angle= -3.8 [hr] (East of Sun)
MOON_POSTN:      187.24d {+12h 28m 58s}   +1.34d {+01d 20' 14"}
MOON_DIST:       119.65 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      181.70,-24.41 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       66.48, -8.11 [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 31 Mar 18 04:23:12 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     820347,   Seg_Num: 0
POINT_RA:         66.033d {+04h 24m 08s} (J2000)
POINT_DEC:       +13.398d {+13d 23' 54"} (J2000)
ROLL:            266.037d
IMG_START_DATE:  18208 TJD;    90 DOY;   18/03/31
IMG_START_TIME:  15411.46 SOD {04:16:51.46} UT,   115.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     544162632
X_OFFSET:        907 [pixels]
Y_OFFSET:        796 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1067
Y_GRB_POS:       956
BINNING_INDEX:   1
IM_URL:          sw00820347000msuni0136.fits
SUN_POSTN:         9.57d {+00h 38m 17s}   +4.12d {+04d 07' 21"}
SUN_DIST:         56.70 [deg]   Sun_angle= -3.8 [hr] (East of Sun)
MOON_POSTN:      187.24d {+12h 28m 58s}   +1.34d {+01d 20' 12"}
MOON_DIST:       119.65 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      181.70,-24.41 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       66.48, -8.11 [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:     Sat 31 Mar 18 04:28:16 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     820347,   Seg_Num: 0
POINT_RA:         66.036d {+04h 24m 09s} (J2000)
POINT_DEC:       +13.401d {+13d 24' 04"} (J2000)
POINT_ROLL:      266.038d
IMG_START_DATE:  18208 TJD;    90 DOY;   18/03/31
IMG_START_TIME:  15569.57 SOD {04:19:29.57} UT,   273.9 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.612
N_STARS:         13
X_OFFSET:        348 [pixels]
Y_OFFSET:        237 [pixels]
X_MAX:           1787 [pixels]
Y_MAX:           1676 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw00820347000msufc0273.fits
SUN_POSTN:         9.58d {+00h 38m 18s}   +4.12d {+04d 07' 26"}
SUN_DIST:         56.70 [deg]   Sun_angle= -3.8 [hr] (East of Sun)
MOON_POSTN:      187.29d {+12h 29m 09s}   +1.32d {+01d 19' 11"}
MOON_DIST:       119.69 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      181.70,-24.41 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       66.48, -8.10 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 31 Mar 18 04:28:41 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     820347,   Seg_Num: 0
GRB_RA:           66.0241d {+04h 24m 05.78s} (J2000),
                  66.2800d {+04h 25m 07.20s} (current),
                  65.3234d {+04h 21m 17.62s} (1950)
GRB_DEC:         +13.3978d {+13d 23' 52.0"} (J2000),
                 +13.4389d {+13d 26' 19.9"} (current),
                 +13.2831d {+13d 16' 59.2"} (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:  18208 TJD;    90 DOY;   18/03/31
IMG_START_TIME:  15499.00 SOD {04:18:19.00} UT,   203.3 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:         9.58d {+00h 38m 18s}   +4.12d {+04d 07' 26"}
SUN_DIST:         56.68 [deg]   Sun_angle= -3.8 [hr] (East of Sun)
MOON_POSTN:      187.29d {+12h 29m 10s}   +1.32d {+01d 19' 06"}
MOON_DIST:       119.71 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      181.70,-24.42 [deg] galactic lon,lat of the burst
ECL_COORDS:       66.47, -8.10 [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 31 Mar 18 04:28:32 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     820347,   Seg_Num: 0
POINT_RA:         66.036d {+04h 24m 09s} (J2000)
POINT_DEC:       +13.401d {+13d 24' 04"} (J2000)
POINT_ROLL:      266.038d
IMG_START_DATE:  18208 TJD;    90 DOY;   18/03/31
IMG_START_TIME:  15569.57 SOD {04:19:29.57} UT,   273.9 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.612
N_STARS:         13
X_OFFSET:        348 [pixels]
Y_OFFSET:        237 [pixels]
X_MAX:           1787 [pixels]
Y_MAX:           1676 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw00820347000msufc0273.fits
SUN_POSTN:         9.58d {+00h 38m 18s}   +4.12d {+04d 07' 26"}
SUN_DIST:         56.70 [deg]   Sun_angle= -3.8 [hr] (East of Sun)
MOON_POSTN:      187.29d {+12h 29m 10s}   +1.32d {+01d 19' 08"}
MOON_DIST:       119.70 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      181.70,-24.41 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       66.48, -8.10 [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 31 Mar 18 04:29:38 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     820347,   Seg_Num: 0
POINT_RA:         66.036d {+04h 24m 09s} (J2000)
POINT_DEC:       +13.401d {+13d 24' 04"} (J2000)
ROLL:            266.038d
IMG_START_DATE:  18208 TJD;    90 DOY;   18/03/31
IMG_START_TIME:  15569.57 SOD {04:19:29.57} UT,   273.9 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     544162790
X_OFFSET:        907 [pixels]
Y_OFFSET:        796 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1067
Y_GRB_POS:       956
BINNING_INDEX:   1
IM_URL:          sw00820347000msuni0294.fits
SUN_POSTN:         9.58d {+00h 38m 18s}   +4.12d {+04d 07' 27"}
SUN_DIST:         56.70 [deg]   Sun_angle= -3.8 [hr] (East of Sun)
MOON_POSTN:      187.30d {+12h 29m 12s}   +1.32d {+01d 18' 55"}
MOON_DIST:       119.71 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      181.70,-24.41 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       66.48, -8.10 [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 31 Mar 18 04:29:49 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     820347,   Seg_Num: 0
POINT_RA:         66.036d {+04h 24m 09s} (J2000)
POINT_DEC:       +13.401d {+13d 24' 04"} (J2000)
ROLL:            266.038d
IMG_START_DATE:  18208 TJD;    90 DOY;   18/03/31
IMG_START_TIME:  15569.57 SOD {04:19:29.57} UT,   273.9 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     544162790
X_OFFSET:        907 [pixels]
Y_OFFSET:        796 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1067
Y_GRB_POS:       956
BINNING_INDEX:   1
IM_URL:          sw00820347000msuni0294.fits
SUN_POSTN:         9.58d {+00h 38m 18s}   +4.12d {+04d 07' 27"}
SUN_DIST:         56.69 [deg]   Sun_angle= -3.8 [hr] (East of Sun)
MOON_POSTN:      187.30d {+12h 29m 12s}   +1.31d {+01d 18' 53"}
MOON_DIST:       119.71 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      181.70,-24.41 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       66.48, -8.10 [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:     Sat 31 Mar 18 04:35:16 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     820347,   Seg_Num: 0
POINT_RA:         66.036d {+04h 24m 09s} (J2000)
POINT_DEC:       +13.401d {+13d 24' 04"} (J2000)
POINT_ROLL:      266.038d
IMG_START_DATE:  18208 TJD;    90 DOY;   18/03/31
IMG_START_TIME:  16172.04 SOD {04:29:32.04} UT,   876.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        5.780
N_STARS:         36
X_OFFSET:        348 [pixels]
Y_OFFSET:        237 [pixels]
X_MAX:           1787 [pixels]
Y_MAX:           1676 [pixels]
DET_THRESH:      20
PHOTO_THRESH:    12
SL_URL:          sw00820347000msufc0876.fits
SUN_POSTN:         9.58d {+00h 38m 19s}   +4.13d {+04d 07' 33"}
SUN_DIST:         56.69 [deg]   Sun_angle= -3.8 [hr] (East of Sun)
MOON_POSTN:      187.35d {+12h 29m 24s}   +1.30d {+01d 17' 48"}
MOON_DIST:       119.76 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      181.70,-24.41 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       66.48, -8.10 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 31 Mar 18 04:35:29 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     820347,   Seg_Num: 0
POINT_RA:         66.036d {+04h 24m 09s} (J2000)
POINT_DEC:       +13.401d {+13d 24' 04"} (J2000)
POINT_ROLL:      266.038d
IMG_START_DATE:  18208 TJD;    90 DOY;   18/03/31
IMG_START_TIME:  16172.04 SOD {04:29:32.04} UT,   876.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        5.780
N_STARS:         36
X_OFFSET:        348 [pixels]
Y_OFFSET:        237 [pixels]
X_MAX:           1787 [pixels]
Y_MAX:           1676 [pixels]
DET_THRESH:      20
PHOTO_THRESH:    12
SL_URL:          sw00820347000msufc0876.fits
SUN_POSTN:         9.58d {+00h 38m 19s}   +4.13d {+04d 07' 33"}
SUN_DIST:         56.69 [deg]   Sun_angle= -3.8 [hr] (East of Sun)
MOON_POSTN:      187.35d {+12h 29m 24s}   +1.30d {+01d 17' 45"}
MOON_DIST:       119.76 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      181.70,-24.41 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       66.48, -8.10 [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 31 Mar 18 04:37:27 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     820347,   Seg_Num: 0
POINT_RA:         66.036d {+04h 24m 09s} (J2000)
POINT_DEC:       +13.401d {+13d 24' 04"} (J2000)
ROLL:            266.038d
IMG_START_DATE:  18208 TJD;    90 DOY;   18/03/31
IMG_START_TIME:  16172.04 SOD {04:29:32.04} UT,   876.3 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     544163392
X_OFFSET:        907 [pixels]
Y_OFFSET:        796 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1067
Y_GRB_POS:       956
BINNING_INDEX:   1
IM_URL:          sw00820347000msuni0897.fits
SUN_POSTN:         9.58d {+00h 38m 19s}   +4.13d {+04d 07' 35"}
SUN_DIST:         56.69 [deg]   Sun_angle= -3.8 [hr] (East of Sun)
MOON_POSTN:      187.37d {+12h 29m 29s}   +1.29d {+01d 17' 22"}
MOON_DIST:       119.78 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      181.70,-24.41 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       66.48, -8.10 [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 31 Mar 18 04:37:42 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     820347,   Seg_Num: 0
POINT_RA:         66.036d {+04h 24m 09s} (J2000)
POINT_DEC:       +13.401d {+13d 24' 04"} (J2000)
ROLL:            266.038d
IMG_START_DATE:  18208 TJD;    90 DOY;   18/03/31
IMG_START_TIME:  16172.04 SOD {04:29:32.04} UT,   876.3 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     544163392
X_OFFSET:        907 [pixels]
Y_OFFSET:        796 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1067
Y_GRB_POS:       956
BINNING_INDEX:   1
IM_URL:          sw00820347000msuni0897.fits
SUN_POSTN:         9.58d {+00h 38m 20s}   +4.13d {+04d 07' 35"}
SUN_DIST:         56.69 [deg]   Sun_angle= -3.8 [hr] (East of Sun)
MOON_POSTN:      187.37d {+12h 29m 29s}   +1.29d {+01d 17' 19"}
MOON_DIST:       119.78 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      181.70,-24.41 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       66.48, -8.10 [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 #22568
C. B. Markwardt (GSFC), A. Deich (PSU), A. Y. Lien (GSFC/UMBC), K. L. Page (U Leicester) and A. Tohuvavohu (PSU) report on behalf of the Neil Gehrels Swift Observatory Team:
At 04:14:55 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 180331A (trigger=820347). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 66.017, +13.398 which is
```
   RA(J2000) = 04h 24m 04s
   Dec(J2000) = +13d 23' 52"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multi-peaked structure with a duration of about 50 sec. The peak count rate was ~1000 counts/sec (15-350 keV), at ~7 sec after the trigger.
The XRT began observing the field at 04:16:48.0 UT, 112.3 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source with an enhanced position: RA, Dec 66.0242, 13.3979 which is equivalent to:
```
   RA(J2000)  = 04h 24m 05.81s
   Dec(J2000) = +13d 23' 52.5"
```
with an uncertainty of 2.2 arcseconds (radius, 90% containment). This location is 25 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 (2.85 x 10^21 cm^-2, Willingale et al. 2013), with an excess column of 3 (+3.23/-2.75) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 115 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 0.60.
Burst Advocate for this burst is C. B. Markwardt (craig.b.markwardt 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 Circular #22569
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team.
Using 1180 s of XRT Photon Counting mode data and 1 UVOT images for GRB 180331A, 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 = 66.02468, +13.39893 which is equivalent to:
```
RA (J2000): 04h 24m 5.92s
Dec (J2000): +13d 23' 56.1"
```
with an uncertainty of 1.8 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 #22570
N. P. M. Kuin (UCL-MSSL) and C. B. Markwardt (GSFC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 180331A 116 s after the BAT trigger (Markwardt et al., GCN Circ. 22568). No optical afterglow consistent with the XRT position (Evans et al. GCN Circ. 22569) 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           116          266          147         >20.2
u_FC               274          524          246         >19.9
white              116         1373          371         >20.4
v                  604         1250           78         >18.6
b                  530         1350           78         >19.4
u                  274          524          246         >19.9
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.60 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #22572
P.A. Evans (U. Leicester) and C. B. Markwardt (GSFC) report on behalf of the Swift-XRT team:
We have analysed 4.2 ks of XRT data for GRB 180331A (Markwardt et al. GCN Circ. 22568), from 115 s to 23.0 ks after the BAT trigger. The data comprise 70 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN Circ. 22569).
The light curve can be modelled with an initial power-law decay with an index of alpha=0.64 (+0.21, -0.19), followed by a break at T+368 s to an alpha of 3.47 (+0.30, -0.25); it then breaks again at T+1.2 ks to a decay of alpha=1.2 (+0.5, -2.4).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.35 (+0.21, -0.20). The best-fitting absorption column is 4.9 (+1.7, -1.5) x 10^21 cm^-2, in excess of 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 6.0 x 10^-11 (7.3 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     4.9 (+1.7, -1.5) x 10^21 cm^-2
Galactic foreground: 2.9 x 10^21 cm^-2
Excess significance: 2.3 sigma
Photon index:	     1.35 (+0.21, -0.20)
```
If the light curve continues to decay with a power-law decay index of 1.2, the count rate at T+24 hours will be 3.3e-4 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.3 x 2.0^-14 (2.4 x 10^-14) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00820347.
This circular is an official product of the Swift-XRT team.
GCN Circular #22574
T. Sakamoto (AGU), 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), 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 180331A (trigger #820347) (Markwardt et al., GCN Circ. 22568). The BAT ground-calculated position is RA, Dec = 66.005, 13.386 deg which is
```
  RA(J2000)  =  04h 24m 01.1s
  Dec(J2000) = +13d 23' 09.2"
```
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment). The partial coding was 81%.
The mask-weighted light curve shows a weak pulse that starts at ~T0, peaks at ~T+9 s, and ends at ~T+50 s. T90 (15-350 keV) is 48.0 +- 22.6 sec (estimated error including systematics).
The time-averaged spectrum from T+0.58 to T+48.58 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.11 +- 1.04, and Epeak of 66.1 +- 28.3 keV (chi squared 57.70 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 6.1 +- 1.0 x 10^-7 erg/cm2 and the 1-sec peak flux measured from T+8.08 sec in the 15-150 keV band is 0.5 +- 0.1 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.46 +- 0.19 (chi squared 64.59 for 57 d.o.f.). All the quoted errors are at the 90% confidence level.
The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/820347/BA/

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Jochen Greiner, last update: 31-Mar-2018 [Disclaimer]