Gamma-ray Burst 170318B

(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 Mar 17 15:28:09 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     743086,   Seg_Num: 0
GRB_RA:          284.279d {+18h 57m 07s} (J2000),
                 284.490d {+18h 57m 58s} (current),
                 283.668d {+18h 54m 40s} (1950)
GRB_DEC:          +6.269d {+06d 16' 10"} (J2000),
                  +6.293d {+06d 17' 36"} (current),
                  +6.202d {+06d 12' 08"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       1901 [cnts]    Image_Peak=108 [image_cnts]
TRIGGER_DUR:     0.512 [sec] 
TRIGGER_INDEX:   124     E_range: 25-100 keV
BKG_INTEN:       20879 [cnts]
BKG_TIME:        55661.22 SOD {15:27:41.22} UT
BKG_DUR:         8 [sec]
GRB_DATE:        17830 TJD;    77 DOY;   17/03/18
GRB_TIME:        55672.55 SOD {15:27:52.55} UT
GRB_PHI:          25.89 [deg]
GRB_THETA:        29.98 [deg]
SOLN_STATUS:     0x20000003
RATE_SIGNIF:     14.93 [sigma]
IMAGE_SIGNIF:    7.21 [sigma]
MERIT_PARAMS:     +1  +0  +0  -1  +2  -3  +0  +1 -27  +0 
SUN_POSTN:       358.37d {+23h 53m 29s}   -0.71d {-00d 42' 19"}
SUN_DIST:         74.06 [deg]   Sun_angle= 4.9 [hr] (West of Sun)
MOON_POSTN:      245.17d {+16h 20m 42s}  -16.17d {-16d 10' 05"}
MOON_DIST:        44.92 [deg]
MOON_ILLUM:      69 [%]
GAL_COORDS:       39.16,  1.60 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      286.26, 28.91 [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 = 209.07,-10.58 [deg].  
COMMENTS:           
COMMENTS:        NOTE: This BAT event is temporally(1.0<100sec) coincident with the FERMI_GBM event (trignum=511543678).

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 18 Mar 17 15:28:17 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      45
TRIGGER_NUM:     511543678
GRB_RA:          287.967d {+19h 11m 52s} (J2000),
                 288.201d {+19h 12m 48s} (current),
                 287.286d {+19h 09m 09s} (1950)
GRB_DEC:          -8.617d {-08d 37' 00"} (J2000),
                  -8.587d {-08d 35' 12"} (current),
                  -8.701d {-08d 42' 03"} (1950)
GRB_ERROR:       22.38 [deg radius, statistical plus systematic]
GRB_INTEN:       122 [cnts/sec]
DATA_SIGNIF:     5.10 [sigma]
INTEG_TIME:      1.024 [sec]
GRB_DATE:        17830 TJD;    77 DOY;   17/03/18
GRB_TIME:        55673.09 SOD {15:27:53.09} UT
GRB_PHI:          67.00 [deg]
GRB_THETA:        80.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO:      0.42
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      52%  GRB
2nd_MOST_LIKELY:  42%  Distant Particles
DETECTORS:       0,1,1, 0,0,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       358.37d {+23h 53m 29s}   -0.71d {-00d 42' 19"}
SUN_DIST:         70.29 [deg]   Sun_angle= 4.7 [hr] (West of Sun)
MOON_POSTN:      245.18d {+16h 20m 42s}  -16.17d {-16d 10' 05"}
MOON_DIST:        42.62 [deg]
MOON_ILLUM:      69 [%]
GAL_COORDS:       27.53, -8.43 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      288.29, 13.69 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2017/bn170318644/quicklook/glg_lc_medres34_bn170318644.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 136.67,-24.67 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(1.0<100sec) coincident with the SWIFT_BAT event (trignum=743086).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 18 Mar 17 15:28:31 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      56
TRIGGER_NUM:     511543678
GRB_RA:          296.280d {+19h 45m 07s} (J2000),
                 296.503d {+19h 46m 01s} (current),
                 295.632d {+19h 42m 32s} (1950)
GRB_DEC:          -1.690d {-01d 41' 23"} (J2000),
                  -1.647d {-01d 38' 50"} (current),
                  -1.812d {-01d 48' 42"} (1950)
GRB_ERROR:       14.56 [deg radius, statistical only]
DATA_SIGNIF:     6.10 [sigma]
DATA_INTERVAL:   1.024 [sec]
GRB_DATE:        17830 TJD;    77 DOY;   17/03/18
GRB_TIME:        55673.09 SOD {15:27:53.09} UT
GRB_PHI:          61.00 [deg]
GRB_THETA:        89.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4153 (Gnd S/W Version number)
SUN_POSTN:       358.37d {+23h 53m 29s}   -0.71d {-00d 42' 18"}
SUN_DIST:         61.86 [deg]   Sun_angle= 4.1 [hr] (West of Sun)
MOON_POSTN:      245.18d {+16h 20m 43s}  -16.17d {-16d 10' 06"}
MOON_DIST:        52.56 [deg]
MOON_ILLUM:      69 [%]
GAL_COORDS:       37.61,-12.70 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      297.95, 19.24 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2017/bn170318644/quicklook/glg_lc_medres34_bn170318644.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_511543678.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file will not be created/available until ~15 min after the trigger.  
COMMENTS:        The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(1.0<100sec) coincident with the SWIFT_BAT event (trignum=743086).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Mar 17 15:29:33 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     743086,   Seg_Num: 0
GRB_RA:          284.3055d {+18h 57m 13.31s} (J2000),
                 284.5158d {+18h 58m 03.78s} (current),
                 283.6946d {+18h 54m 46.71s} (1950)
GRB_DEC:          +6.2987d {+06d 17' 55.3"} (J2000),
                  +6.3225d {+06d 19' 21.1"} (current),
                  +6.2313d {+06d 13' 52.8"} (1950)
GRB_ERROR:       6.3 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       5.39e-10 [erg/cm2/sec]
GRB_SIGNIF:      4.69 [sigma]
IMG_START_DATE:  17830 TJD;    77 DOY;   17/03/18
IMG_START_TIME:  55746.32 SOD {15:29:06.32} UT,   73.8 [sec] since BAT Trigger Time
TAM[0-3]:        327.65 237.22 261.65 243.51
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       358.37d {+23h 53m 30s}   -0.71d {-00d 42' 17"}
SUN_DIST:         74.04 [deg]   Sun_angle= 4.9 [hr] (West of Sun)
MOON_POSTN:      245.19d {+16h 20m 45s}  -16.17d {-16d 10' 12"}
MOON_DIST:        44.95 [deg]
MOON_ILLUM:      69 [%]
GAL_COORDS:       39.20,  1.59 [deg] galactic lon,lat of the burst
ECL_COORDS:      286.30, 28.93 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 2.35 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Mar 17 15:29:46 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     743086,   Seg_Num: 0
GRB_RA:          284.3055d {+18h 57m 13.3s} (J2000),
                 284.5158d {+18h 58m 03.7s} (current),
                 283.6946d {+18h 54m 46.7s} (1950)
GRB_DEC:          +6.2987d {+06d 17' 55.3"} (J2000),
                  +6.3225d {+06d 19' 21.1"} (current),
                  +6.2313d {+06d 13' 52.8"} (1950)
GRB_ERROR:       6.1 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       22 [cnts]
IMG_START_DATE:  17830 TJD;    77 DOY;   17/03/18
IMG_START_TIME:  55746.32 SOD {15:29:06.32} UT,   73.8 [sec] since BAT Trigger Time
CENTROID_X:      297.08,  raw= 297  [pixels]
CENTROID_Y:      359.32,  raw= 359  [pixels]
ROLL:            92.52 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   143.60
GRB_POS_XRT_Z:   -21.96
IMAGE_URL:       sw00743086000msxps_rw.img
SUN_POSTN:       358.37d {+23h 53m 30s}   -0.71d {-00d 42' 17"}
SUN_DIST:         74.04 [deg]   Sun_angle= 4.9 [hr] (West of Sun)
MOON_POSTN:      245.19d {+16h 20m 45s}  -16.17d {-16d 10' 13"}
MOON_DIST:        44.95 [deg]
MOON_ILLUM:      69 [%]
GAL_COORDS:       39.20,  1.59 [deg] galactic lon,lat of the burst
ECL_COORDS:      286.30, 28.93 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Mar 17 15:29:43 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     743086,   Seg_Num: 0
GRB_RA:          284.3055d {+18h 57m 13.3s} (J2000),
                 284.5158d {+18h 58m 03.7s} (current),
                 283.6946d {+18h 54m 46.7s} (1950)
GRB_DEC:          +6.2987d {+06d 17' 55.3"} (J2000),
                  +6.3225d {+06d 19' 21.1"} (current),
                  +6.2313d {+06d 13' 52.8"} (1950)
GRB_ERROR:       6.1 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       22 [cnts]
IMG_START_DATE:  17830 TJD;    77 DOY;   17/03/18
IMG_START_TIME:  55746.32 SOD {15:29:06.32} UT,   73.8 [sec] since BAT Trigger Time
CENTROID_X:      297.08,  raw= 297  [pixels]
CENTROID_Y:      359.32,  raw= 359  [pixels]
ROLL:            92.52 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   143.60
GRB_POS_XRT_Z:   -21.96
IMAGE_URL:       sw00743086000msxps_rw.img
SUN_POSTN:       358.37d {+23h 53m 30s}   -0.71d {-00d 42' 17"}
SUN_DIST:         74.04 [deg]   Sun_angle= 4.9 [hr] (West of Sun)
MOON_POSTN:      245.19d {+16h 20m 45s}  -16.17d {-16d 10' 13"}
MOON_DIST:        44.95 [deg]
MOON_ILLUM:      69 [%]
GAL_COORDS:       39.20,  1.59 [deg] galactic lon,lat of the burst
ECL_COORDS:      286.30, 28.93 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Mar 17 15:31:30 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     743086,   Seg_Num: 0
GRB_RA:          284.279d {+18h 57m 07s} (J2000),
                 284.490d {+18h 57m 58s} (current),
                 283.668d {+18h 54m 40s} (1950)
GRB_DEC:          +6.269d {+06d 16' 10"} (J2000),
                  +6.293d {+06d 17' 36"} (current),
                  +6.202d {+06d 12' 08"} (1950)
GRB_DATE:        17830 TJD;    77 DOY;   17/03/18
GRB_TIME:        55672.55 SOD {15:27:52.55} UT
TRIGGER_INDEX:   124
GRB_PHI:          25.89 [deg]
GRB_THETA:        29.98 [deg]
DELTA_TIME:      -11.00 [sec]
TRIGGER_DUR:     0.512 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     14.93 [sigma]
IMAGE_SIGNIF:    7.21 [sigma]
LC_URL:          sw00743086000msb.lc
SUN_POSTN:       358.37d {+23h 53m 30s}   -0.70d {-00d 42' 15"}
SUN_DIST:         74.07 [deg]   Sun_angle= 4.9 [hr] (West of Sun)
MOON_POSTN:      245.20d {+16h 20m 49s}  -16.17d {-16d 10' 22"}
MOON_DIST:        44.90 [deg]
MOON_ILLUM:      69 [%]
GAL_COORDS:       39.16,  1.60 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      286.26, 28.91 [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 = 209.07,-10.58 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Mar 17 15:32:40 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     743086,   Seg_Num: 0
POINT_RA:        284.297d {+18h 57m 11s} (J2000)
POINT_DEC:        +6.258d {+06d 15' 29"} (J2000)
POINT_ROLL:      92.522d
IMG_START_DATE:  17830 TJD;    77 DOY;   17/03/18
IMG_START_TIME:  55756.72 SOD {15:29:16.72} UT,   84.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.419
N_STARS:         54
X_OFFSET:        376 [pixels]
Y_OFFSET:        292 [pixels]
X_MAX:           1335 [pixels]
Y_MAX:           1251 [pixels]
DET_THRESH:      15
PHOTO_THRESH:    8
SL_URL:          sw00743086000msufc0084.fits
SUN_POSTN:       358.37d {+23h 53m 30s}   -0.70d {-00d 42' 14"}
SUN_DIST:         74.05 [deg]   Sun_angle= 4.9 [hr] (West of Sun)
MOON_POSTN:      245.21d {+16h 20m 51s}  -16.17d {-16d 10' 28"}
MOON_DIST:        44.90 [deg]
MOON_ILLUM:      69 [%]
GAL_COORDS:       39.16,  1.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      286.28, 28.89 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Mar 17 15:32:42 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     743086,   Seg_Num: 0
POINT_RA:        284.297d {+18h 57m 11s} (J2000)
POINT_DEC:        +6.258d {+06d 15' 29"} (J2000)
POINT_ROLL:      92.522d
IMG_START_DATE:  17830 TJD;    77 DOY;   17/03/18
IMG_START_TIME:  55756.72 SOD {15:29:16.72} UT,   84.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.419
N_STARS:         54
X_OFFSET:        376 [pixels]
Y_OFFSET:        292 [pixels]
X_MAX:           1335 [pixels]
Y_MAX:           1251 [pixels]
DET_THRESH:      15
PHOTO_THRESH:    8
SL_URL:          sw00743086000msufc0084.fits
SUN_POSTN:       358.37d {+23h 53m 30s}   -0.70d {-00d 42' 14"}
SUN_DIST:         74.05 [deg]   Sun_angle= 4.9 [hr] (West of Sun)
MOON_POSTN:      245.21d {+16h 20m 51s}  -16.17d {-16d 10' 28"}
MOON_DIST:        44.90 [deg]
MOON_ILLUM:      69 [%]
GAL_COORDS:       39.16,  1.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      286.28, 28.89 [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 Mar 17 15:34:02 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     743086,   Seg_Num: 0
POINT_RA:        284.297d {+18h 57m 11s} (J2000)
POINT_DEC:        +6.258d {+06d 15' 29"} (J2000)
ROLL:            92.522d
IMG_START_DATE:  17830 TJD;    77 DOY;   17/03/18
IMG_START_TIME:  55756.72 SOD {15:29:16.72} UT,   84.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     511543775
X_OFFSET:        696 [pixels]
Y_OFFSET:        612 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       856
Y_GRB_POS:       772
BINNING_INDEX:   1
IM_URL:          sw00743086000msuni0103.fits
SUN_POSTN:       358.38d {+23h 53m 30s}   -0.70d {-00d 42' 13"}
SUN_DIST:         74.05 [deg]   Sun_angle= 4.9 [hr] (West of Sun)
MOON_POSTN:      245.22d {+16h 20m 54s}  -16.18d {-16d 10' 34"}
MOON_DIST:        44.89 [deg]
MOON_ILLUM:      69 [%]
GAL_COORDS:       39.16,  1.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      286.28, 28.89 [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 Mar 17 15:34:20 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     743086,   Seg_Num: 0
POINT_RA:        284.297d {+18h 57m 11s} (J2000)
POINT_DEC:        +6.258d {+06d 15' 29"} (J2000)
ROLL:            92.522d
IMG_START_DATE:  17830 TJD;    77 DOY;   17/03/18
IMG_START_TIME:  55756.72 SOD {15:29:16.72} UT,   84.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     511543775
X_OFFSET:        696 [pixels]
Y_OFFSET:        612 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       856
Y_GRB_POS:       772
BINNING_INDEX:   1
IM_URL:          sw00743086000msuni0103.fits
SUN_POSTN:       358.38d {+23h 53m 30s}   -0.70d {-00d 42' 13"}
SUN_DIST:         74.05 [deg]   Sun_angle= 4.9 [hr] (West of Sun)
MOON_POSTN:      245.23d {+16h 20m 54s}  -16.18d {-16d 10' 36"}
MOON_DIST:        44.89 [deg]
MOON_ILLUM:      69 [%]
GAL_COORDS:       39.16,  1.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      286.28, 28.89 [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 Mar 17 15:41:08 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     743086,   Seg_Num: 0
POINT_RA:        284.298d {+18h 57m 12s} (J2000)
POINT_DEC:        +6.261d {+06d 15' 38"} (J2000)
POINT_ROLL:      92.522d
IMG_START_DATE:  17830 TJD;    77 DOY;   17/03/18
IMG_START_TIME:  55968.79 SOD {15:32:48.79} UT,   296.2 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.974
N_STARS:         20
X_OFFSET:        376 [pixels]
Y_OFFSET:        292 [pixels]
X_MAX:           1335 [pixels]
Y_MAX:           1251 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    4
SL_URL:          sw00743086000msufc0296.fits
SUN_POSTN:       358.38d {+23h 53m 31s}   -0.70d {-00d 42' 06"}
SUN_DIST:         74.05 [deg]   Sun_angle= 4.9 [hr] (West of Sun)
MOON_POSTN:      245.28d {+16h 21m 08s}  -16.19d {-16d 11' 11"}
MOON_DIST:        44.85 [deg]
MOON_ILLUM:      69 [%]
GAL_COORDS:       39.16,  1.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      286.28, 28.90 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Mar 17 15:41:26 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     743086,   Seg_Num: 0
POINT_RA:        284.298d {+18h 57m 12s} (J2000)
POINT_DEC:        +6.261d {+06d 15' 38"} (J2000)
POINT_ROLL:      92.522d
IMG_START_DATE:  17830 TJD;    77 DOY;   17/03/18
IMG_START_TIME:  55968.79 SOD {15:32:48.79} UT,   296.2 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.974
N_STARS:         20
X_OFFSET:        376 [pixels]
Y_OFFSET:        292 [pixels]
X_MAX:           1335 [pixels]
Y_MAX:           1251 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    4
SL_URL:          sw00743086000msufc0296.fits
SUN_POSTN:       358.38d {+23h 53m 31s}   -0.70d {-00d 42' 06"}
SUN_DIST:         74.05 [deg]   Sun_angle= 4.9 [hr] (West of Sun)
MOON_POSTN:      245.29d {+16h 21m 09s}  -16.19d {-16d 11' 12"}
MOON_DIST:        44.85 [deg]
MOON_ILLUM:      69 [%]
GAL_COORDS:       39.16,  1.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      286.28, 28.90 [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 Mar 17 15:41:43 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     743086,   Seg_Num: 0
GRB_RA:          284.3061d {+18h 57m 13.46s} (J2000),
                 284.5164d {+18h 58m 03.92s} (current),
                 283.6952d {+18h 54m 46.85s} (1950)
GRB_DEC:          +6.2994d {+06d 17' 57.8"} (J2000),
                  +6.3232d {+06d 19' 23.6"} (current),
                  +6.2320d {+06d 13' 55.3"} (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:  17830 TJD;    77 DOY;   17/03/18
IMG_START_TIME:  55850.00 SOD {15:30:50.00} UT,   177.4 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       358.38d {+23h 53m 31s}   -0.70d {-00d 42' 05"}
SUN_DIST:         74.05 [deg]   Sun_angle= 4.9 [hr] (West of Sun)
MOON_POSTN:      245.29d {+16h 21m 09s}  -16.19d {-16d 11' 14"}
MOON_DIST:        44.87 [deg]
MOON_ILLUM:      69 [%]
GAL_COORDS:       39.20,  1.59 [deg] galactic lon,lat of the burst
ECL_COORDS:      286.30, 28.93 [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 0.11% < P(seren) < 0.58%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Mar 17 15:43:04 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     743086,   Seg_Num: 0
POINT_RA:        284.298d {+18h 57m 12s} (J2000)
POINT_DEC:        +6.261d {+06d 15' 38"} (J2000)
ROLL:            92.522d
IMG_START_DATE:  17830 TJD;    77 DOY;   17/03/18
IMG_START_TIME:  55968.79 SOD {15:32:48.79} UT,   296.2 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     511543987
X_OFFSET:        696 [pixels]
Y_OFFSET:        612 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       856
Y_GRB_POS:       772
BINNING_INDEX:   1
IM_URL:          sw00743086000msuni0315.fits
SUN_POSTN:       358.38d {+23h 53m 32s}   -0.70d {-00d 42' 04"}
SUN_DIST:         74.05 [deg]   Sun_angle= 4.9 [hr] (West of Sun)
MOON_POSTN:      245.30d {+16h 21m 12s}  -16.19d {-16d 11' 20"}
MOON_DIST:        44.84 [deg]
MOON_ILLUM:      69 [%]
GAL_COORDS:       39.16,  1.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      286.28, 28.90 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        This notice was forced out after watchdog timer expiring -- most likely due to missing packet(s);  
COMMENTS:        as a consequence some of the fields may be incoorect (eg TRIGGER_NUM,RA,DEC).

GCN Circular #20908
A. Cholden-Brown (PSU), S. D. Barthelmy (GSFC), D. N. Burrows (PSU), J. A. Kennea (PSU), H. A. Krimm (CRESST/NSF/USRA), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the Swift Team:
At 15:27:52 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 170318B (trigger=743086). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 284.279, +6.269, which is
```
   RA(J2000)  =  18h 57m 07s
   Dec(J2000) = +06d 16' 10"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a single peak with a duration of about 3 sec. The peak count rate was ~1900 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 15:29:06.3 UT, 73.7 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source located at RA, Dec 284.30606, 6.29833 which is equivalent to:
```
   RA(J2000)  = 18h 57m 13.45s
   Dec(J2000) = +06d 17' 54.0"
```
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This location is 141 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 does not constrain the column density.
The initial flux in the 2.5 s image was 5.39e-10 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 84 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 large, but uncertain extinction expected.
Burst Advocate for this burst is A. Cholden-Brown (aaronb AT swift.psu.edu). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.)

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Mar 17 15:43:26 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     743086,   Seg_Num: 0
POINT_RA:        284.298d {+18h 57m 12s} (J2000)
POINT_DEC:        +6.261d {+06d 15' 38"} (J2000)
ROLL:            92.522d
IMG_START_DATE:  17830 TJD;    77 DOY;   17/03/18
IMG_START_TIME:  55968.79 SOD {15:32:48.79} UT,   296.2 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     511543987
X_OFFSET:        696 [pixels]
Y_OFFSET:        612 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       856
Y_GRB_POS:       772
BINNING_INDEX:   1
IM_URL:          sw00743086000msuni0315.fits
SUN_POSTN:       358.38d {+23h 53m 32s}   -0.70d {-00d 42' 04"}
SUN_DIST:         74.05 [deg]   Sun_angle= 4.9 [hr] (West of Sun)
MOON_POSTN:      245.30d {+16h 21m 13s}  -16.19d {-16d 11' 22"}
MOON_DIST:        44.83 [deg]
MOON_ILLUM:      69 [%]
GAL_COORDS:       39.16,  1.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      286.28, 28.90 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.  
COMMENTS:        This notice was forced out after watchdog timer expiring -- most likely due to missing packet(s);  
COMMENTS:        as a consequence some of the fields may be incoorect (eg TRIGGER_NUM,RA,DEC).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Mar 17 16:02:29 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     743086,   Seg_Num: 0
POINT_RA:        284.298d {+18h 57m 12s} (J2000)
POINT_DEC:        +6.261d {+06d 15' 38"} (J2000)
POINT_ROLL:      92.522d
IMG_START_DATE:  17830 TJD;    77 DOY;   17/03/18
IMG_START_TIME:  56547.85 SOD {15:42:27.85} UT,   875.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.360
N_STARS:         105
X_OFFSET:        136 [pixels]
Y_OFFSET:        52 [pixels]
X_MAX:           1575 [pixels]
Y_MAX:           1491 [pixels]
DET_THRESH:      17
PHOTO_THRESH:    10
SL_URL:          sw00743086000msufc0875.fits
SUN_POSTN:       358.39d {+23h 53m 35s}   -0.70d {-00d 41' 45"}
SUN_DIST:         74.07 [deg]   Sun_angle= 4.9 [hr] (West of Sun)
MOON_POSTN:      245.46d {+16h 21m 51s}  -16.22d {-16d 12' 59"}
MOON_DIST:        44.71 [deg]
MOON_ILLUM:      69 [%]
GAL_COORDS:       39.16,  1.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      286.28, 28.90 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 18 Mar 17 16:02:46 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     743086,   Seg_Num: 0
POINT_RA:        284.298d {+18h 57m 12s} (J2000)
POINT_DEC:        +6.261d {+06d 15' 38"} (J2000)
POINT_ROLL:      92.522d
IMG_START_DATE:  17830 TJD;    77 DOY;   17/03/18
IMG_START_TIME:  56547.85 SOD {15:42:27.85} UT,   875.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.360
N_STARS:         105
X_OFFSET:        136 [pixels]
Y_OFFSET:        52 [pixels]
X_MAX:           1575 [pixels]
Y_MAX:           1491 [pixels]
DET_THRESH:      17
PHOTO_THRESH:    10
SL_URL:          sw00743086000msufc0875.fits
SUN_POSTN:       358.39d {+23h 53m 35s}   -0.70d {-00d 41' 44"}
SUN_DIST:         74.07 [deg]   Sun_angle= 4.9 [hr] (West of Sun)
MOON_POSTN:      245.47d {+16h 21m 52s}  -16.22d {-16d 13' 00"}
MOON_DIST:        44.71 [deg]
MOON_ILLUM:      69 [%]
GAL_COORDS:       39.16,  1.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      286.28, 28.90 [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 Mar 17 16:04:08 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     743086,   Seg_Num: 0
POINT_RA:        284.298d {+18h 57m 12s} (J2000)
POINT_DEC:        +6.261d {+06d 15' 38"} (J2000)
ROLL:            92.522d
IMG_START_DATE:  17830 TJD;    77 DOY;   17/03/18
IMG_START_TIME:  56547.85 SOD {15:42:27.85} UT,   875.3 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     511544566
X_OFFSET:        695 [pixels]
Y_OFFSET:        611 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       855
Y_GRB_POS:       771
BINNING_INDEX:   1
IM_URL:          sw00743086000msuni0894.fits
SUN_POSTN:       358.39d {+23h 53m 35s}   -0.70d {-00d 41' 43"}
SUN_DIST:         74.07 [deg]   Sun_angle= 4.9 [hr] (West of Sun)
MOON_POSTN:      245.48d {+16h 21m 54s}  -16.22d {-16d 13' 07"}
MOON_DIST:        44.70 [deg]
MOON_ILLUM:      69 [%]
GAL_COORDS:       39.16,  1.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      286.28, 28.90 [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 Mar 17 16:04:15 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     743086,   Seg_Num: 0
POINT_RA:        284.298d {+18h 57m 12s} (J2000)
POINT_DEC:        +6.261d {+06d 15' 38"} (J2000)
ROLL:            92.522d
IMG_START_DATE:  17830 TJD;    77 DOY;   17/03/18
IMG_START_TIME:  56547.85 SOD {15:42:27.85} UT,   875.3 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     511544566
X_OFFSET:        695 [pixels]
Y_OFFSET:        611 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       855
Y_GRB_POS:       771
BINNING_INDEX:   1
IM_URL:          sw00743086000msuni0894.fits
SUN_POSTN:       358.39d {+23h 53m 35s}   -0.70d {-00d 41' 43"}
SUN_DIST:         74.07 [deg]   Sun_angle= 4.9 [hr] (West of Sun)
MOON_POSTN:      245.48d {+16h 21m 55s}  -16.22d {-16d 13' 08"}
MOON_DIST:        44.70 [deg]
MOON_ILLUM:      69 [%]
GAL_COORDS:       39.16,  1.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      286.28, 28.90 [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 #20909
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Using promptly downlinked XRT event data for GRB 170318B, we find an enhanced XRT position of the afterglow: RA, Dec: 284.3062, 6.2994 which is equivalent to:
```
   RA (J2000)  = 18 57 13.49
   Dec (J2000) = +06 17 57.9
```
with an uncertainty of 2.1 arcseconds (radius, 90% confidence). Analysis of the promptly available data is online at http://www.swift.ac.uk/sper/743086.
Position enhancement is is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177).
This circular is an official product of the Swift-XRT team.
GCN Circular #20910
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team.
Using 839 s of XRT Photon Counting mode data and 1 UVOT images for GRB 170318B, 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 = 284.30611, +6.29924 which is equivalent to:
```
RA (J2000): 18h 57m 13.47s
Dec (J2000): +06d 17' 57.3"
```
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 #20913
P. Veres and C. Meegan (both UAH) report on behalf of the Fermi GBM Team:
"At 15:27:53.09 UT on 18 March 2018, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 170318B (trigger 511543678 / 170318644). which was also detected by the Swift/BAT (Cholden-Brown et al. 2008, GCN 20908) The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 93 degrees.
The GBM light curve shows a single peak with a duration (T90) of about 4 s (50-300 keV). The time-averaged spectrum from T0-3.3 s to T0+1.8 s is adequately fit by a simple power law function with index -1.40 +/- 0.10.
The event fluence (10-1000 keV) in this time interval is (8.0 +/- 1.4)E-7 erg/cm^2. The 1-sec peak photon flux measured starting from T0-0.8 s in the 10-1000 keV band is 1.9 +/- 0.2 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN Circular #20918
J.A. Kennea (PSU), P.A. Evans (U. Leicester), S.L. Gibson (U. Leicester), J.P. Osborne (U. Leicester), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU) and report on behalf of the Swift-XRT team: report on behalf of the Swift-XRT team:
We have analysed 7.2 ks of XRT data for GRB 170318B, from 64 s to 41.1 ks after the BAT trigger. The data comprise 95 s in Windowed Timing (WT) mode (the first 8 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode.
The light curve can be modelled with an initial rise, with a power-law index of alpha=-0.5 (+0.4, -0.5), followed by a break at T+134 s to an alpha of 2.96 (+0.16, -0.15).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.6 (+/-0.4). The best-fitting absorption column is 6.4 (+1.7, -1.4) x 10^22 cm^-2, in excess of the Galactic value of 1.4 x 10^22 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 2.3 (+/-0.6) and a best-fitting absorption column of 6.2 (+2.1, -1.7) x 10^22 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 8.0 x 10^-11 (3.5 x 10^-10) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     6.2 (+2.1, -1.7) x 10^22 cm^-2
Galactic foreground: 1.4 x 10^22 cm^-2
Excess significance: 4.6 sigma
Photon index:	     2.3 (+/-0.6)
```
If the light curve continues to decay with a power-law decay index of 2.96, the count rate at T+24 hours will be 4.5 x 10^-8 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.6 x 10^-18 (1.6 x 10^-17) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00743086.
This circular is an official product of the Swift-XRT team.
GCN Circular #20919
A. A. Breeveld (UCL-MSSL) and A. Cholden-Brown (PSU) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 170318B 84 s after the BAT trigger (Cholden-Brown et al., GCN Circ. 20908). No optical afterglow consistent with the XRT position (Goad et al. GCN Circ. 20910) 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            84          234          147         >20.4
u_FC               296          546          246         >19.8
white               84         6145          530         >21.0
v                  626         6557          432         >19.4
b                  552         5940          236         >20.0
u                  296         7172          659         >20.2
w1                 675         6967          432         >19.9
m2                5123         5323          197         >19.3
w2                 601         6352          216         >19.6
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 4.51 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #20921
Alan M. Watson (UNAM), Nat Butler (ASU), 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 (ASU), and Vicki Toy (UMD) report:
We observed the field of GRB 170318B (Cholden-Brown et al., GCN 20908) 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 2017/03 19.47 to 2017/03 19.51 UTC (19.76 to 20.76 hours after the BAT trigger), obtaining a total of 0.71 hours exposure in the r and i bands and 0.30 hours exposure in the Z, Y, J, and H bands.
For a source within the Swift-XRT enhanced error circle (Goad et al., GCN 20910), in comparison with the USNO-B1 and 2MASS catalogs, we obtain the following upper limits (3-sigma):
```
 r    > 25.64
 i    > 24.39
 Z    > 22.65
 Y    > 22.43
 J    > 21.38
 H    > 20.98
```
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 #20923
H. A. Krimm (NSF/USRA), S. D. Barthelmy (GSFC), A. Cholden-Brown (PSU), J. R. Cummings (CPI), N. Gehrels (GSFC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (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 170318B (trigger #743086) (Cholden-Brown, et al., GCN Circ. 20908). The BAT ground-calculated position is RA, Dec = 284.229, 6.335 deg which is
```
    RA(J2000)  =  18h 56m 54.9s
    Dec(J2000) = +06d 20' 04.5"
```
with an uncertainty of 3.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 67%.
The mask-weighted light curve shows an initial symmetric pulse of duration ~20 sec from about T-15 sec to T+5 sec. This is followed by low-level extended emission from ~T+30 to T+160 sec. T90 (15-350 keV) is 160.0 +- 35.8 sec (estimated error including systematics).
The time-averaged spectrum from T-15.33 to T+160.67 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.84 +- 0.59. The fluence in the 15-150 keV band is 5.5 +- 1.9 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T-7.83 sec in the 15-150 keV band is 0.1 +- 0.1 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/743086/BA/
GCN Circular #20957
K. P. Mooley (Hintze Fellow, Oxford) , T. D. Staley, R. P. Fender (Oxford), G. E. Anderson (Curtin), T. Cantwell (Manchester), D. Titterington, S. H. Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, P. Scott (Cambridge), K. Grainge, A. Scaife (Manchester)
The AMI Large Array robotically triggered on the Swift alert for GRB 170318B (Cholden-Brown et al., GCN 20908) as part of the 4pisky program, and subsequent follow up observations were obtained up to 10 days post-burst. Our observations at 15 GHz on 2016 Mar 19.11, Mar 21.17 and Mar 23.24 (UT) do not reveal any radio source at the XRT location (Goad et al., GCN 20910), with 3sigma upper limits of 300 uJy, 150 uJy and 315 uJy respectively.
We thank the AMI staff for scheduling these observations. The AMI-GRB database is a log of all GRB follow up observations with the AMI, and is available at http://4pisky.org/ami-grb/.

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Jochen Greiner, last update: 31-Mar-2017 [Disclaimer]