Gamma-ray Burst 160303A

(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:     Thu 03 Mar 16 10:55:15 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     677495,   Seg_Num: 0
GRB_RA:          168.681d {+11h 14m 44s} (J2000),
                 168.896d {+11h 15m 35s} (current),
                 168.017d {+11h 12m 04s} (1950)
GRB_DEC:         +22.742d {+22d 44' 33"} (J2000),
                 +22.654d {+22d 39' 15"} (current),
                 +23.015d {+23d 00' 54"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       1496 [cnts]    Image_Peak=116 [image_cnts]
TRIGGER_DUR:     0.256 [sec] 
TRIGGER_INDEX:   481     E_range: 50-350 keV
BKG_INTEN:       22181 [cnts]
BKG_TIME:        39272.07 SOD {10:54:32.07} UT
BKG_DUR:         8 [sec]
GRB_DATE:        17450 TJD;    63 DOY;   16/03/03
GRB_TIME:        39282.05 SOD {10:54:42.05} UT
GRB_PHI:         -171.22 [deg]
GRB_THETA:        22.59 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     29.41 [sigma]
IMAGE_SIGNIF:    8.20 [sigma]
MERIT_PARAMS:     +1  +0  +0  -2  +3  -1  +0  +0 +95  +0 
SUN_POSTN:       344.61d {+22h 58m 26s}   -6.56d {-06d 33' 47"}
SUN_DIST:        163.39 [deg]   Sun_angle= 11.7 [hr] (West of Sun)
MOON_POSTN:      270.38d {+18h 01m 32s}  -18.21d {-18d 12' 40"}
MOON_DIST:       107.16 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      218.91, 67.68 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      160.52, 16.42 [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 = 161.57,-17.33 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Thu 03 Mar 16 10:55:18 UT
NOTICE_TYPE:    INTEGRAL SPI ACS Trigger
TRIGGER_NUM:    7385,   Sub_Num: 0
GRB_INTEN:      11.74 [sigma]  
GRB_TIME:       39282.17 SOD {10:54:42.17} UT
GRB_DATE:       17450 TJD;    63 DOY;   16/03/03
COMMENTS:       INTEGRAL SPI_ACS GRB Trigger.
COMMENTS:       Time_Scale=0.2000 and Time_Error=0.1000.
COMMENTS:
COMMENTS:       NOTE: This SPIACS event is temporally(0.0<100sec) coincident with the
+SWIFT_BAT event (trignum=677495).
COMMENTS:
COMMENTS:       The SPIACS lightcurve can be found at:
COMMENTS:       ftp://isdcarc.unige.ch/arc/FTP/ibas/spiacs/2016-03/2016-03-03T10-54-42.0603-25944-56208+-0.lc

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 03 Mar 16 10:56:51 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     677495,   Seg_Num: 0
POINT_RA:        168.702d {+11h 14m 49s} (J2000)
POINT_DEC:       +22.757d {+22d 45' 27"} (J2000)
IMG_START_DATE:  17450 TJD;    63 DOY;   16/03/03
IMG_START_TIME:  39386.18 SOD {10:56:26.18} UT,   104.1 [sec] since BAT Trigger Time
COUNTS:          37    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        4    Max_iter_allowed= 4
ERROR_CODE:      2
COMMENTS:        SWIFT-XRT Nack Position.  
COMMENTS:        Algorithm did not converge; too many iterations.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 03 Mar 16 10:58:35 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     677495,   Seg_Num: 0
GRB_RA:          168.681d {+11h 14m 44s} (J2000),
                 168.896d {+11h 15m 35s} (current),
                 168.017d {+11h 12m 04s} (1950)
GRB_DEC:         +22.742d {+22d 44' 33"} (J2000),
                 +22.654d {+22d 39' 15"} (current),
                 +23.015d {+23d 00' 54"} (1950)
GRB_DATE:        17450 TJD;    63 DOY;   16/03/03
GRB_TIME:        39282.05 SOD {10:54:42.05} UT
TRIGGER_INDEX:   481
GRB_PHI:         -171.22 [deg]
GRB_THETA:        22.59 [deg]
DELTA_TIME:      -37.00 [sec]
TRIGGER_DUR:     0.256 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     29.41 [sigma]
IMAGE_SIGNIF:    8.20 [sigma]
LC_URL:          sw00677495000msb.lc
SUN_POSTN:       344.61d {+22h 58m 26s}   -6.56d {-06d 33' 44"}
SUN_DIST:        163.39 [deg]   Sun_angle= 11.7 [hr] (West of Sun)
MOON_POSTN:      270.41d {+18h 01m 40s}  -18.21d {-18d 12' 42"}
MOON_DIST:       107.18 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      218.91, 67.68 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      160.52, 16.42 [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 = 161.57,-17.33 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 03 Mar 16 10:59:26 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     677495,   Seg_Num: 0
POINT_RA:        168.702d {+11h 14m 48s} (J2000)
POINT_DEC:       +22.757d {+22d 45' 25"} (J2000)
POINT_ROLL:      14.277d
IMG_START_DATE:  17450 TJD;    63 DOY;   16/03/03
IMG_START_TIME:  39390.93 SOD {10:56:30.93} UT,   108.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.367
N_STARS:         10
X_OFFSET:        309 [pixels]
Y_OFFSET:        516 [pixels]
X_MAX:           1268 [pixels]
Y_MAX:           1475 [pixels]
DET_THRESH:      13
PHOTO_THRESH:    7
SL_URL:          sw00677495000msufc0108.fits
SUN_POSTN:       344.61d {+22h 58m 26s}   -6.56d {-06d 33' 43"}
SUN_DIST:        163.37 [deg]   Sun_angle= 11.7 [hr] (West of Sun)
MOON_POSTN:      270.42d {+18h 01m 41s}  -18.21d {-18d 12' 42"}
MOON_DIST:       107.18 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      218.89, 67.70 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      160.53, 16.44 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 03 Mar 16 10:59:45 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     677495,   Seg_Num: 0
POINT_RA:        168.702d {+11h 14m 48s} (J2000)
POINT_DEC:       +22.757d {+22d 45' 25"} (J2000)
POINT_ROLL:      14.277d
IMG_START_DATE:  17450 TJD;    63 DOY;   16/03/03
IMG_START_TIME:  39390.93 SOD {10:56:30.93} UT,   108.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.367
N_STARS:         10
X_OFFSET:        309 [pixels]
Y_OFFSET:        516 [pixels]
X_MAX:           1268 [pixels]
Y_MAX:           1475 [pixels]
DET_THRESH:      13
PHOTO_THRESH:    7
SL_URL:          sw00677495000msufc0108.fits
SUN_POSTN:       344.61d {+22h 58m 26s}   -6.56d {-06d 33' 42"}
SUN_DIST:        163.37 [deg]   Sun_angle= 11.7 [hr] (West of Sun)
MOON_POSTN:      270.43d {+18h 01m 42s}  -18.21d {-18d 12' 42"}
MOON_DIST:       107.18 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      218.89, 67.70 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      160.53, 16.44 [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:     Thu 03 Mar 16 11:00:54 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     677495,   Seg_Num: 0
POINT_RA:        168.702d {+11h 14m 48s} (J2000)
POINT_DEC:       +22.757d {+22d 45' 25"} (J2000)
ROLL:            14.277d
IMG_START_DATE:  17450 TJD;    63 DOY;   16/03/03
IMG_START_TIME:  39390.93 SOD {10:56:30.93} UT,   108.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     478695406
X_OFFSET:        628 [pixels]
Y_OFFSET:        835 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       788
Y_GRB_POS:       995
BINNING_INDEX:   1
IM_URL:          sw00677495000msuni0124.fits
SUN_POSTN:       344.61d {+22h 58m 27s}   -6.56d {-06d 33' 41"}
SUN_DIST:        163.37 [deg]   Sun_angle= 11.7 [hr] (West of Sun)
MOON_POSTN:      270.44d {+18h 01m 45s}  -18.21d {-18d 12' 43"}
MOON_DIST:       107.19 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      218.89, 67.70 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      160.53, 16.44 [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:     Thu 03 Mar 16 11:01:11 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     677495,   Seg_Num: 0
POINT_RA:        168.702d {+11h 14m 48s} (J2000)
POINT_DEC:       +22.757d {+22d 45' 25"} (J2000)
ROLL:            14.277d
IMG_START_DATE:  17450 TJD;    63 DOY;   16/03/03
IMG_START_TIME:  39390.93 SOD {10:56:30.93} UT,   108.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     478695406
X_OFFSET:        628 [pixels]
Y_OFFSET:        835 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       788
Y_GRB_POS:       995
BINNING_INDEX:   1
IM_URL:          sw00677495000msuni0124.fits
SUN_POSTN:       344.61d {+22h 58m 27s}   -6.56d {-06d 33' 41"}
SUN_DIST:        163.37 [deg]   Sun_angle= 11.7 [hr] (West of Sun)
MOON_POSTN:      270.44d {+18h 01m 45s}  -18.21d {-18d 12' 43"}
MOON_DIST:       107.19 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      218.89, 67.70 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      160.53, 16.44 [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:     Thu 03 Mar 16 11:03:19 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     677495,   Seg_Num: 0
GRB_RA:          168.6999d {+11h 14m 47.97s} (J2000),
                 168.9144d {+11h 15m 39.45s} (current),
                 168.0357d {+11h 12m 08.56s} (1950)
GRB_DEC:         +22.7412d {+22d 44' 28.3"} (J2000),
                 +22.6529d {+22d 39' 10.4"} (current),
                 +23.0139d {+23d 00' 49.9"} (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:  17450 TJD;    63 DOY;   16/03/03
IMG_START_TIME:  39398.00 SOD {10:56:38.00} UT,   115.9 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       344.61d {+22h 58m 27s}   -6.56d {-06d 33' 39"}
SUN_DIST:        163.38 [deg]   Sun_angle= 11.7 [hr] (West of Sun)
MOON_POSTN:      270.46d {+18h 01m 50s}  -18.21d {-18d 12' 44"}
MOON_DIST:       107.21 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      218.93, 67.69 [deg] galactic lon,lat of the burst
ECL_COORDS:      160.54, 16.43 [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 1.1% < P(seren) < 2.8%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 03 Mar 16 11:07:45 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     677495,   Seg_Num: 0
POINT_RA:        168.703d {+11h 14m 49s} (J2000)
POINT_DEC:       +22.756d {+22d 45' 20"} (J2000)
POINT_ROLL:      14.281d
IMG_START_DATE:  17450 TJD;    63 DOY;   16/03/03
IMG_START_TIME:  39602.91 SOD {11:00:02.91} UT,   320.9 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.639
N_STARS:         18
X_OFFSET:        69 [pixels]
Y_OFFSET:        276 [pixels]
X_MAX:           1508 [pixels]
Y_MAX:           1715 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw00677495000msufc0320.fits
SUN_POSTN:       344.62d {+22h 58m 28s}   -6.56d {-06d 33' 35"}
SUN_DIST:        163.37 [deg]   Sun_angle= 11.7 [hr] (West of Sun)
MOON_POSTN:      270.50d {+18h 02m 00s}  -18.21d {-18d 12' 45"}
MOON_DIST:       107.24 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      218.90, 67.70 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      160.54, 16.44 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 03 Mar 16 11:08:04 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     677495,   Seg_Num: 0
POINT_RA:        168.703d {+11h 14m 49s} (J2000)
POINT_DEC:       +22.756d {+22d 45' 20"} (J2000)
POINT_ROLL:      14.281d
IMG_START_DATE:  17450 TJD;    63 DOY;   16/03/03
IMG_START_TIME:  39602.91 SOD {11:00:02.91} UT,   320.9 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.639
N_STARS:         18
X_OFFSET:        69 [pixels]
Y_OFFSET:        276 [pixels]
X_MAX:           1508 [pixels]
Y_MAX:           1715 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw00677495000msufc0320.fits
SUN_POSTN:       344.62d {+22h 58m 28s}   -6.56d {-06d 33' 34"}
SUN_DIST:        163.37 [deg]   Sun_angle= 11.7 [hr] (West of Sun)
MOON_POSTN:      270.50d {+18h 02m 01s}  -18.21d {-18d 12' 45"}
MOON_DIST:       107.25 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      218.90, 67.70 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      160.54, 16.44 [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:     Thu 03 Mar 16 11:08:16 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     677495,   Seg_Num: 0
GRB_RA:          168.7005d {+11h 14m 48.12s} (J2000),
                 168.9150d {+11h 15m 39.59s} (current),
                 168.0363d {+11h 12m 08.71s} (1950)
GRB_DEC:         +22.7424d {+22d 44' 32.6"} (J2000),
                 +22.6541d {+22d 39' 14.7"} (current),
                 +23.0151d {+23d 00' 54.3"} (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:  17450 TJD;    63 DOY;   16/03/03
IMG_START_TIME:  39398.00 SOD {10:56:38.00} UT,   115.9 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       344.62d {+22h 58m 28s}   -6.56d {-06d 33' 34"}
SUN_DIST:        163.38 [deg]   Sun_angle= 11.7 [hr] (West of Sun)
MOON_POSTN:      270.51d {+18h 02m 01s}  -18.21d {-18d 12' 46"}
MOON_DIST:       107.25 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      218.93, 67.70 [deg] galactic lon,lat of the burst
ECL_COORDS:      160.54, 16.43 [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 1.1% < P(seren) < 2.8%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 03 Mar 16 11:09:17 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     677495,   Seg_Num: 0
POINT_RA:        168.703d {+11h 14m 49s} (J2000)
POINT_DEC:       +22.756d {+22d 45' 20"} (J2000)
ROLL:            14.281d
IMG_START_DATE:  17450 TJD;    63 DOY;   16/03/03
IMG_START_TIME:  39602.91 SOD {11:00:02.91} UT,   320.9 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     478695618
X_OFFSET:        628 [pixels]
Y_OFFSET:        835 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       788
Y_GRB_POS:       995
BINNING_INDEX:   1
IM_URL:          sw00677495000msuni0336.fits
SUN_POSTN:       344.62d {+22h 58m 28s}   -6.56d {-06d 33' 33"}
SUN_DIST:        163.37 [deg]   Sun_angle= 11.7 [hr] (West of Sun)
MOON_POSTN:      270.51d {+18h 02m 04s}  -18.21d {-18d 12' 46"}
MOON_DIST:       107.26 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      218.90, 67.70 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      160.54, 16.44 [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:     Thu 03 Mar 16 11:09:36 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     677495,   Seg_Num: 0
POINT_RA:        168.703d {+11h 14m 49s} (J2000)
POINT_DEC:       +22.756d {+22d 45' 20"} (J2000)
ROLL:            14.281d
IMG_START_DATE:  17450 TJD;    63 DOY;   16/03/03
IMG_START_TIME:  39602.91 SOD {11:00:02.91} UT,   320.9 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     478695618
X_OFFSET:        628 [pixels]
Y_OFFSET:        835 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       788
Y_GRB_POS:       995
BINNING_INDEX:   1
IM_URL:          sw00677495000msuni0336.fits
SUN_POSTN:       344.62d {+22h 58m 28s}   -6.56d {-06d 33' 33"}
SUN_DIST:        163.37 [deg]   Sun_angle= 11.7 [hr] (West of Sun)
MOON_POSTN:      270.52d {+18h 02m 04s}  -18.21d {-18d 12' 46"}
MOON_DIST:       107.26 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      218.90, 67.70 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      160.54, 16.44 [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:     Thu 03 Mar 16 11:13:15 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     677495,   Seg_Num: 0
POINT_RA:        168.703d {+11h 14m 49s} (J2000)
POINT_DEC:       +22.756d {+22d 45' 21"} (J2000)
POINT_ROLL:      14.280d
IMG_START_DATE:  17450 TJD;    63 DOY;   16/03/03
IMG_START_TIME:  40156.21 SOD {11:09:16.21} UT,   874.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.474
N_STARS:         28
X_OFFSET:        69 [pixels]
Y_OFFSET:        276 [pixels]
X_MAX:           1508 [pixels]
Y_MAX:           1715 [pixels]
DET_THRESH:      13
PHOTO_THRESH:    7
SL_URL:          sw00677495000msufc0874.fits
SUN_POSTN:       344.62d {+22h 58m 29s}   -6.56d {-06d 33' 29"}
SUN_DIST:        163.37 [deg]   Sun_angle= 11.7 [hr] (West of Sun)
MOON_POSTN:      270.55d {+18h 02m 12s}  -18.21d {-18d 12' 47"}
MOON_DIST:       107.29 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      218.90, 67.70 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      160.54, 16.44 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 03 Mar 16 11:13:36 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     677495,   Seg_Num: 0
POINT_RA:        168.703d {+11h 14m 49s} (J2000)
POINT_DEC:       +22.756d {+22d 45' 21"} (J2000)
POINT_ROLL:      14.280d
IMG_START_DATE:  17450 TJD;    63 DOY;   16/03/03
IMG_START_TIME:  40156.21 SOD {11:09:16.21} UT,   874.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.474
N_STARS:         28
X_OFFSET:        69 [pixels]
Y_OFFSET:        276 [pixels]
X_MAX:           1508 [pixels]
Y_MAX:           1715 [pixels]
DET_THRESH:      13
PHOTO_THRESH:    7
SL_URL:          sw00677495000msufc0874.fits
SUN_POSTN:       344.62d {+22h 58m 29s}   -6.56d {-06d 33' 29"}
SUN_DIST:        163.37 [deg]   Sun_angle= 11.7 [hr] (West of Sun)
MOON_POSTN:      270.56d {+18h 02m 13s}  -18.21d {-18d 12' 48"}
MOON_DIST:       107.29 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      218.90, 67.70 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      160.54, 16.44 [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:     Thu 03 Mar 16 11:14:45 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     677495,   Seg_Num: 0
POINT_RA:        168.703d {+11h 14m 49s} (J2000)
POINT_DEC:       +22.756d {+22d 45' 21"} (J2000)
ROLL:            14.280d
IMG_START_DATE:  17450 TJD;    63 DOY;   16/03/03
IMG_START_TIME:  40156.21 SOD {11:09:16.21} UT,   874.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     478696172
X_OFFSET:        628 [pixels]
Y_OFFSET:        835 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       788
Y_GRB_POS:       995
BINNING_INDEX:   1
IM_URL:          sw00677495000msuni0890.fits
SUN_POSTN:       344.62d {+22h 58m 29s}   -6.56d {-06d 33' 28"}
SUN_DIST:        163.37 [deg]   Sun_angle= 11.7 [hr] (West of Sun)
MOON_POSTN:      270.57d {+18h 02m 16s}  -18.21d {-18d 12' 48"}
MOON_DIST:       107.30 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      218.90, 67.70 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      160.54, 16.44 [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:     Thu 03 Mar 16 11:15:06 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     677495,   Seg_Num: 0
POINT_RA:        168.703d {+11h 14m 49s} (J2000)
POINT_DEC:       +22.756d {+22d 45' 21"} (J2000)
ROLL:            14.280d
IMG_START_DATE:  17450 TJD;    63 DOY;   16/03/03
IMG_START_TIME:  40156.21 SOD {11:09:16.21} UT,   874.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     478696172
X_OFFSET:        628 [pixels]
Y_OFFSET:        835 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       788
Y_GRB_POS:       995
BINNING_INDEX:   1
IM_URL:          sw00677495000msuni0890.fits
SUN_POSTN:       344.62d {+22h 58m 29s}   -6.56d {-06d 33' 28"}
SUN_DIST:        163.37 [deg]   Sun_angle= 11.7 [hr] (West of Sun)
MOON_POSTN:      270.57d {+18h 02m 17s}  -18.21d {-18d 12' 48"}
MOON_DIST:       107.31 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:      218.90, 67.70 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      160.54, 16.44 [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 #19126
A. P. Beardmore (U Leicester), D. N. Burrows (PSU), P.A. Evans (U Leicester), L. M. McCauley (PSU), K. L. Page (U Leicester) and D. M. Palmer (LANL) report on behalf of the Swift Team:
At 10:54:42 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 160303A (trigger=677495). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 168.681, +22.742 which is
```
   RA(J2000) = 11h 14m 44s
   Dec(J2000) = +22d 44' 33"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a single peak structure with a duration of about 0.5 s sec. There is some suggestion of additional peaks at T-1 and T+5. The peak count rate was ~6000 counts/sec (15-350 keV), at ~0.1 sec after the trigger.
The XRT began observing the field at 10:56:26.1 UT, 104.1 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source with an enhanced position: RA, Dec 168.7005, 22.7424 which is equivalent to:
```
   RA(J2000)  = 11h 14m 48.11s
   Dec(J2000) = +22d 44' 32.5"
```
with an uncertainty of 2.2 arcseconds (radius, 90% containment). This location is 64 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 1.07 x 10^20 cm^-2 (Willingale et al. 2013).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 108 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 0.02.
Burst Advocate for this burst is A. P. Beardmore (apb AT star.le.ac.uk). 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 #19127
L. Elenin (KIAM), E. Mazaeva (IKI), A. Volnova (IKI), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:
We observed the field of the Swift GRB 160303A (Beardmore et al., GCN 19126) with 0.4-m telescope of ISON-NM observatory starting on Mar., 03 (UT) 10:56:02, i.e. ~80 seconds after burst trigger. We obtained 30 unfiltered images of 30 s exposure. We do not detect any source within XRT error circle (Beardmore et al., GCN 19126) both in the first image and in a combined image:
```
UT start   t-T0         Exp.      Filter  UL (3sigma)
          (mid.,days)    (s)
10:56:02  0.00110        1*30    Clear   19.8
10:56:02  0.00971       30*30    Clear   21.7
```
The photometry is based on nearby USNO-B1.0 stars
GCN Circular #19128
D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ), S. Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto) and N. Kawai(Tokyo Tech) report on behalf of MITSuME and OISTER collaboration:
We observed the field of GRB 160303A (Beardmore et al., GCNC 19126) with the optical three color (g', Rc and Ic) CCD camera attached to the MITSuME 50cm telescope of Okayama Astrophysical Observatory.
The observation started on 2016-03-03 10:57:10 UT (~2.5 min after the burst). We did not find any new point source within the XRT circle (Beardmore et al., GCNC 19126) in all the three bands.
Three sigma upper limits of the OT are listed below. We used SDSS-DR8 catalog for flux calibration.
```
#T0+[day]  MID-UT    T-EXP[sec]   g'    Rc     Ic
-----------------------------------------------------
0.00532    11:02:21     540.0   >18.5  >18.6  >18.0
0.01940    11:22:38    2520.0   >19.5  >19.6  >19.0
-----------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]
```
GCN Circular #19129
S. Dichiara (U. Ferrara, ICRANet), C. Guidorzi (U. Ferrara), S. Kobayashi (LJMU), A. Gomboc (U. Nova Gorica), C.G. Mundell (U. Bath), on behalf of a larger collaboration report:
The 2-m LCOGT Faulkes Telescope North began observing Swift GRB 160303A (Beardmore et al., GCN 19126) on March 03, 11:18 UT (23 minutes after the burst trigger) with i' filter. Inside the XRT error circle we find no source down to i'> 21.2 mag in a 5x120s exposure (at 28.7 min, mid time), as calibrated against nearby SDSS stars, in agreement with the limits reported by Elenin et al. (GCN 19127).
GCN Circular #19130
Y.Tachibana, T.Fujiwara, T. Yoshii, Y. Saito, H. Ohuchi, Y. Yano, S. Kurita, S.Harita, Y.Muraki, Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:
We searched for the optical counterpart of GRB 160303A (Beardmore et al., GCN Circular #19126) with the optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan.
The observation started on 2016-03-03 10:55:44 UT (~1 min after the burst). We did not find any new point source within XRT circle in all three bands.
We obtained following limits for the magnitudes.
```
T0+[hour]    MID-UT     T-EXP[sec]      g'         Rc          Ic
----------------------------------------------------------------------------
  0.43        11:20:38         2610       >20.3     >20.4    >19.6
----------------------------------------------------------------------------
T0+ : Elapsed time after the burst 
T-EXP: Total Exposure time 
We used GSC2.3 catalog for flux calibration.
```
GCN Circular #19131
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 (GSFC/STScI), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), Jos=E9 A. de Diego (UNAM), Leonid Georgiev (UNAM), Jes=FAs Gonz=E1lez (UNAM), Carlos Rom=E1n-Z=FA=F1iga (UNAM), Neil Gehrels (GSFC), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy (UMD) report:
We observed the field of GRB 160303A (Beardmore, et al., GCN 19126) 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 2016/03 3.46 to 2016/03 3.52 UTC (1.8 minutes to 1.50 hours after the BAT trigger), obtaining a total of 1.02 hours exposure in the r and i bands and 0.44 hours exposure in the Z, Y, J, and H bands.
We detect an uncatalogued source within the Swift-XRT error circle, in comparison with the SDSS DR9 and 2MASS catalogs, we obtain the following detections and upper limits (3-sigma):
```
  r = 22.95 +/- 0.31
  i = 22.65 +/- 0.23
  Z > 21.98
  Y = 21.83 +/- 0.36
  J > 21.30
  H > 21.01
```
These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. The source is located at RA, Dec= 11:14:48.12, +22:44:32.6 (J2000, +/-0.5").
We thank the staff of the Observatorio Astron=F3mico Nacional in San Pedro M=E1rtir.
GCN Circular #19132
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team.
Using 2035 s of XRT Photon Counting mode data and 2 UVOT images for GRB 160303A, 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 = 168.70075, +22.74213 which is equivalent to:
```
RA (J2000): 11h 14m 48.18s
Dec (J2000): +22d 44' 31.7"
```
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 #19133
J. Wren, W.T. Vestrand, P. Wozniak, and H. Davis of Los Alamos National Laboratory report:
The RAPTOR network of robotic optical telescopes made observations of Swift trigger 677495 (Beardmore, et al., GCN 19126). The burst location was within the field of our wide-field monitor located in Maui, HI, which began a 10 s integration of the location beginning at 10:54:38.19 UT, 3.86 s before the Swift trigger time and during the gamma-ray emitting interval. We do not detect an optical counterpart to a limiting magnitude of 10.5. Our 3-sigma limiting magnitudes are based on a comparison of our unfiltered image to the Tycho-2 V-band catalog.
GCN Circular #19134
S.W.K. Emery (UCL-MSSL) and A. P. Beardmore (U Leicester) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 160303A 109 s after the BAT trigger (Beardmore et al., GCN Circ. 19126). We detect a fading source consistent with the XRT position (Beardmore et al. GCN Circ. 19126) and the RATIR optical and NIR afterglow detections (Butler et al. GCN Circ 19131) in the initial UVOT u filter 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            109          259          147         >21.9
u_FC                321          571          246          20.75
white               109         2061          450         >22.5
b                   576         2037          136         >19.9
w1                  700         2161           77         >20.5
m2                 1426         1445           19         >19.5
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.02 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #19136
A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), D. Malesani (DARK/NBI), N.R. Tanvir (U. Leicester), Z. Cano (U. Iceland), M. Messa (Stockholm Univ., Oskar Klein Centre), E. Gafton (NOT, Stockholm Univ. and Oskar Klein Centre) and I. R. Losada (Nordita and Stockholm Univ.) report on behalf of a larger collaboration:
We observed the field of the possibly short GRB 160303A (Beardmore et al., GCN 19126) with MOSCA at the 2.5m Nordic Optical Telescope (La Palma, Spain). Observations started at 21:32 UT (10.63 hr after the burst). In an 8x300s r-band exposure we detect a source consistent with the counterpart candidate identified by RATIR (Butler et al. GCN 19131), and also seen by UVOT (Emery et al. GCN 19134).
Comparing with SDSS field stars we obtain a photometric value of r=23.43+/-0.15 (AB). This would imply only a modest (if any) fading compared to the RATIR observation. This may be indicative of a significant contribution from an underlying host galaxy.
We do note that the coordinates that we measure are slightly offset from those given in the RATIR GCN, being our object marginally outside the refined XRT error circle(Evans et al., GCN 19132, http://www.swift.ac.uk/xrt_positions/00677495/
), at the following coordinates (J2000, +/- 0.3"):
```
RA = 11:14:48.06
Dec = +22:44:32.2
```
GCN Circular #19137
D.N. Burrows (PSU), P.A. Evans (U. Leicester), S.L. Gibson (U. Leicester), J.P. Osborne (U. Leicester), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), T.G.R. Roegiers (PSU), L.M. McCauley (PSU) and A.P. Beardmore report on behalf of the Swift-XRT team:
We have analysed 7.0 ks of XRT data for GRB 160303A (Beardmore et al. GCN Circ. 19126), from 87 s to 23.3 ks after the BAT trigger. The data comprise 9 s in Windowed Timing (WT) mode (taken while Swift was slewing), with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN Circ. 19132).
The light curve can be modelled with a power-law decay with a decay index of alpha=2.36 (+0.17, -0.16).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.70 (+0.24, -0.22). The best-fitting absorption column is 5.2 (+6.7, -4.1) x 10^20 cm^-2, consistent with the Galactic value of 1.1 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.8 x 10^-11 (4.1 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     5.2 (+6.7, -4.1) x 10^20 cm^-2
Galactic foreground: 1.1 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.70 (+0.24, -0.22)
```
If the light curve continues to decay with a power-law decay index of 2.36, the count rate at T+24 hours will be 6.7 x 10^-7 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.6 x 10^-17 (2.8 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/00677495.
This circular is an official product of the Swift-XRT team.
GCN Circular #19138
T. Sakamoto, Y. Kitaoka, A. Yoshida (AGU)
We observed the field of GRB 160303A detected by Swift (trigger #677495; Beardmore et al., GCN Circ. 19126) with the iTelescope.Net (http://www.itelescope.net) T21 (Plane Wave 17" CDK) telescope located at the New Mexico Skies Observatory (NM, USA).
15 images of 60 sec exposures were taken in the R filter starting from March 3 11:19:26 (UT) about 25 minutes after the trigger and stopped on March 3 11:38:20 (UT). We do not detect the optical afterglow both in the individual images and the stacked image at the X-ray and the optical afterglow position (Evans et al., GCN Circ. 19132; Butler et al., GCN Circ. 19131). The estimated five sigma upper limit of the combined image (total exposure of 900 sec) is ~18.3 using the USNO-B1 catalog.
GCN Circular #19139
GRB 160303A SMA observation
Y. Urata (NCU), K.Y Huang (NTNU), and G. Petitpas (SMA)
We observed the optical afterglow position of GRB 130303A (Butler et al., GCN Circ. 19131) using the Sub-Millimeter Array (SMA). The observation in 230 GHz band was started at March 3 12:47 (UT) about 1.9 hrs after the burst. Our preliminary analysis shows no counterpart brighter than 2.4 mJy (3-sigma).
GCN Circular #19140
Soomin Jeong (SKKU/IAA-CSIC), Myungshin Im, Changsu Choi and Gu Lim (CEOU/SNU) on behalf of a larger collaboration:
We observed the field of GRB160303A (Beardmore et al., GCN 19126) with CQUEAN at the Otto Struve 2.1 m telescope in McDonald Observatory, Texas. The observation started at 11:44, Mar 03 UT (i.e. 0.83 hr post burst) and the observation was conducted in r-, i-, R-, z- band.
In the median combined image (5 x 120s) of i-band, a possible counterpart is detected near the centre of XRT enhanced position (Evans et al., GCN 19132). We noticed that our i-band detection is slightly offset from a previously identified position by RATIR (Butler et al., GCN 19131) and found another marginal detection at the RATIR detection, i.e., outskirt of XRT enhanced position (Evans et al., GCN 19132).
Faint features are barely detected also in an 5 x 120s, r-band exposure, however the detection error is too big to reveal its reality. It is in relatively outskirt within XRT enhanced error circle and at the previously reported optical position (Butler et al., GCN 19131; Emery et al., GCN 19134). In comparison to other reports, the detection in i-band looks like a fading afterglow (Butler et al., GCN 19131), and the position of the possible object in r-band is coincident to the previous optical detection by RATIR (Butler et al., GCN 19131) and NOT (De Ugarte et al., GCN 19136). The faint r-band source could be the host galaxy or highly contaminated counterpart from the underlying host.
The analysis of R- and z-band images is still ongoing.
```
T_mid (hr)  Exposure (s)     Filter       Magnitude (AB)
-----------------------------------------------------------------------------------

0.92               5x120               i          22.54 +/- 0.26 

1.13               5x120               r          23.06 +/- 0.41

------------------------------------------------------------------------------------
```
The fields are calibrated to a nearby star at RA=168.701176, Dec=22.745212 from SDSS.
GCN Circular #19141
Myungshin Im (CEOU/SNU), Hyun-Il Sung (KASI), Yuji Urata (NCU), Soomin Jeong (SKKU/IAA-CSIC)
We observed the field of GRB 160303A (Beardmore et al. GCN 19126) using the 1.8m telescope at the Bohyunsan Optical Astronomy Observatory =E2=80=8B =E2=80=8B (BOAO) in Korea. The observation started at 2016-02-28 13:31:46 UT, =E2=80=8B =E2=80=8B or about 2.6 hours after the BAT alert.
We clearly identify the afterglow at the location of the RATIR detection (Butler et al. GCN 19131) with R =3D 22.75 +- 0.12 mag in a stacked image of 6 x 5 min frames (Mid-point: 2016-02-28 13:54). Together with the =E2=80=8B result=E2=80=8B at 10 =E2=80=8B =E2=80=8B hrs after the BAT alert (de Ugarte Postiago et al. =E2=80=8B=E2=80=8B GCN 19136), our photometry unambiguously confirms the fading nature of this source. Further observation and the analysis of the data are planned.
We thank the BOAO staffs for their assistance with the observation.
GCN Circular #19142
S. Klose, A. Nicuesa Guelbenzu (both TLS Tautenburg), T. Kruehler (MPE Garching), D. Malesani (DARK/NBI) and J. Greiner (MPE Garching) report on behalf of a larger collaboration:
We observed the field of GRB 160303A (Swift trigger 677495; Beardmore et al., GCN #19126) with FORS2 at ESO's Very Large Telescope. Imaging in the R-band filter started at 05:40:42 UT on 2016-03-04, 18.8 hr after the GRB trigger.
In a 4x25 s exposure, we clearly detect the candidate counterpart (Butler et al. GCN#19131, Emery & Beardmore, GCN#19134, de Ugarte Postigo et al. GCN#19136) at a position consistent with the one provided by de Ugarte Postigo et al. (GCN#19136). The source appears point-like in the image which has a stellar PSF with a FWHM of 0.72".
Calibrating our data against r-band photometry of field stars from the SDSS catalog, we measure a preliminary AB magnitude of
r = 24.11 +- 0.15
This implies significant fading against the earlier measurements from Butler et al. (GCN#19131) and de Ugarte Postigo et al. (GCN#19136), indicating that this source is the GRB afterglow (see also Im et al., GCN#19141).
GCN Circular #19143
A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), C.C. Thoene (IAA-CSIC), V. Casanova (IAA-CSIC) report on behalf of a larger collaboration:
We observed the field of the possibly short GRB 160303A (Beardmore et al., GCN 19126) with the 1.5 m OSN telescope (Sierra Nevada Observatory, Granada, Spain). Observation consisted of 15x300s exposures in R-band, ranging from 01:37-3:00 UT (mean epoch at 15.41 hr after the burst).
In the combined image the GRB afterglow (Butler et al., GCN 19131; Emery et al. GCN 19134; de Ugarte Postigo, GCN 19136; Jeong et al. GCN19140; Im et al. GCN 19141; Klose et al. GCN 19142) is seen at a magnitude of r(AB) = 23.67 +/- 0.27 as compared to SDSS stars.
This seems to indicate confirm the decay as compared with the data of RATIR (Butler et al., GCN 19131), NOT (de Ugarte Postigo, GCN 19136) and CQUEAN (Jeong et al. GCN19140), BOAO (Im et al. GCN 19141) and FORS (Klose et al. GCN 19142). In any case the possible decay would be shallower than the typical GRB, with a decay slope of alpha ~ 0.5 (F_nu ~ t^-alpha).
GCN Circular #19144
J. Graham, J. Bolmer, P. Wiseman and J. Greiner (all MPE Garching) report on behalf of the GROND team:
We observed the field of GRB 160303A (Swift trigger 677495; Beardmore et al., GCN #19126) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2m MPG telescope at the ESO La Silla Observatory (Chile).
Observations started at 03:27 UT on 2016-03-04, 16.5h after the GRB trigger. They were performed at an average seeing of 1.3" and at an average airmass of 1.6.
We detect a single source at the edge of the Swift-XRT error circle reported by Evans et al. (GCN #19132) consistent with the optical candidate from de Ugarte Postigo et al. (GCN #19136) and Klose et al. (GCN #19142)
Based on 66 min of exposure in g'r'i'z' and 60 min in JHK, at a mid-time of 04:54 UT, we derive the following preliminary magnitudes and upper limits (in AB system):
```
g' = 24.2 +/- 0.1 mag,
r' = 24.0 +/- 0.1 mag,
i' = 23.9 +/- 0.2 mag,
z' = 23.5 +/- 0.3 mag,
J > 21.1 mag,
H > 20.1 mag, and
K > 19.5 mag.
```
Given detections and upper limits are calibrated against SDSS as well as 2MASS field stars. No correction for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.014 mag in the direction of the burst (Schlafly & Finkbeiner 2011) has been applied.
GCN Circular #19146
Eleonora Troja (GSFC), Nat Butler (ASU), Alan M. Watson (UNAM),=20 Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer=20 (UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (GSFC/STScI), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), Jos=E9 A. de Diego (UNAM), Leonid Georgiev (UNAM), Jes=FAs Gonz=E1lez (UNAM), Carlos Rom=E1n-Z=FA=F1iga (UNAM), Neil Gehrels=20 (GSFC), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy (UMD) report:
We observed the field of GRB 160303A (Beardmore, et al., GCN 19126) 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 2016/03 4.12 to 2016/03 4.53 UTC (16.00 to 25.72 hours after the BAT trigger), obtaining a total of 5.52 hours exposure in the r and i bands and 2.27 hours exposure in the Z, Y, J, and H bands.
The source reported by Butler et al. (GCN 19131) is not detected in our=20 images. In comparison with the SDSS DR9 and 2MASS catalogs, we obtain=20 the following upper limits (3-sigma):
```
   r    > 23.77
   i    > 23.88
   Z    > 22.37
   Y    > 21.77
   J    > 21.52
   H    > 21.45
```
These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. Our upper limits are consistent with the GROND measurements (Graham et al., GCN 19144) and confirm that the source was the afterglow of GRB160303A.
We thank the staff of the Observatorio Astron=F3mico Nacional in San Pedro M=E1rtir.
GCN Circular #19147
W. Fong (University of Arizona) reports on behalf of a larger collaboration:
"We observed the location of the possibly short-duration GRB 160303A (Beardmore et al., GCN 19126) with MMTCam mounted on the 6.5-m MMT at a mid-time of 2016 Mar 4.232 UT (18.64 hr post-burst). We obtained 9x200-sec of r-band observations in 1.0" seeing at a mean airmass of 1.2. We detect the optical afterglow (Butler et al., GCN 19131) with a magnitude of r(AB)~23.90 +/- 0.15 (calibrated to SDSS) at a position consistent with the NOT position (de Ugarte Postigo et al., GCN 19136). Our measured afterglow brightness is consistent with the VLT value at a similar epoch (Klose et al., GCN 19142)."
GCN Circular #19148
T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC), A. P. Beardmore (U Leicester), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), J. P. Norris (BSU), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU) (i.e. the Swift-BAT team):
Using the data set from T-61 to T+200 sec from the recent telemetry downlink, we report further analysis of BAT GRB 160303A (trigger #677495) (Beardmore, et al. GCN Circ. 19126). The BAT ground-calculated position is RA, Dec = 168.710, 22.710 deg which is
```
  RA(J2000)  =  11h 14m 50.3s
  Dec(J2000) = +22d 42' 35.1"
```
with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 96%.
The mask-weighted light curve shows a short spike that start and peaks at ~T0, and ends at ~T+0.4 s. There is a hint of a weak tail that lasts till ~T+5 s T90 (15-350 keV) is 5.0 +- 0.8 sec (estimated error including systematics).
Note that for this burst, the auto process generates fairly inconsistent results of the burst durations (ranging from T90 of ~ 0.4 s to T90 of ~ 18 s) when using light curves with different time bins and/or different length of data range. This is likely due to the ambiguous weak-tail feature in the light curve after the short spike.
Thus, we did further checks of the reality of the weak tail by an alternative Bayesian Block method based on Scargle et al. (2013), and by searching for detections in images created using different time intervals. We conclude that there is likely no burst emission after ~T+5 s, because no burst structure is picked out by the alternative Bayesian Block method afterwards, and also the signal-to-noise ratio is only about one in images created after ~T+5. The image created using T+1 s to T+5 s gives a signal-to-noise ratio of ~ 4.
The lag analysis using the 8-ms binned light curve shows a lag of 24 ms +- 24 ms for the 100-350 keV to 25-50 keV band, which is inconclusive for the burst nature due to the weakness of the burst.
We therefore decided to report T90 based on results using data till ~T0+200 s, which gives a T90 of ~ 5 s and is consistent with our checks. However, due to the relatively low significance of the tail. We report the spectral analyses for both the total range and the the short spike.
The time-averaged spectrum from T-0.1 to T+5.3 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.01 +- 0.33. The fluence in the 15-150 keV band is 1.5 +- 0.3 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T-0.09 sec in the 15-150 keV band is 1.0 +- 0.1 ph/cm2/sec.
The spectrum of the short spike from T-0.09 to T+0.40 sec is best fit by a simple power-law model. The power law index of the short-spike spectrum is 0.84 +- 0.20. The fluence in the 15-150 keV band is 8.78 +- 1.1 x 10^-8 erg/cm2. 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/677495/BA/
GCN Circular #19149
W. Fong (University of Arizona) reports:
"We observed the field of GRB 160303A (Beardmore et al., GCN 19126) with the Karl G. Jansky Very Large Array (VLA) beginning on 2016 Mar 4.218 UT (18.32 hr post-burst) at a mean frequency of 9.8 GHz. In 1 hour of observations, we do not detect any radio source within or around the enhanced XRT position (Evans et al., GCN 19132) or the optical afterglow position (Butler et al., GCN 19131; de Ugarte Postigo et al., GCN 19136) to a 3-sigma limit of 15.2 microJy. We therefore place a 3-sigma limit of 15.2 microJy on the radio afterglow of GRB 160303A at 18.32 hr after the burst.
We thank the VLA staff for quickly executing these observations."
GCN Circular #19150
J. Bolmer, J. Greiner (both MPE Garching) and D.A. Kann (TLS Tautenburg) report on behalf of the GROND team:
We re-observed the field of GRB 160303A (Swift trigger 677495; Beardmore et al., GCN #19126) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2m MPG telescope at the ESO La Silla Observatory (Chile).
Observations started at 03:58 UT on 2016-03-05, 41.1h after the GRB trigger. They were performed at an average seeing of 1.0" and at an average airmass of 1.6.
We still detect a faint source at the initially reported position (Graham et al. GCN#19144, de Ugarte Postigo et al. (GCN #19136)).
Based on 96 min of exposure in g'r'i'z', at a mid-time of 04:52 UT, we derive the following preliminary magnitudes and upper limits (in AB system):
```
g' = 25.2 +/- 0.2 mag,
r' = 25.1 +/- 0.2 mag,
i' > 24.3 mag,
z' > 24.4 mag,
```
Given detections and upper limits are calibrated against SDSS field stars. No correction for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.014 mag in the direction of the burst (Schlafly & Finkbeiner 2011) has been applied.
Combining our GROND measurements with those from 10.63 h after the GRB (de Ugarte Postigo et al., GCN #19136), we obtain a decay slope of alpha = - 1.1 +/- 0.2 in the r' band.
GCN Circular #19151
I.A. Smith (Rice U.), N.R. Tanvir (U. of Leicester), and Y. Urata (NCU) report:
We observed the location of the possibly short GRB 160303A (Beardmore et al., GCN Circ. 19126) using the SCUBA-2 sub-millimeter continuum camera on the James Clerk Maxwell Telescope. The observation started at 11:56 UT on 2016-03-03, corresponding to 62 minutes after the burst trigger. Exposures totaling 2.0 hours were made in good weather conditions. No source was detected, with the RMS background noise being 1.4 mJy/beam at 850 microns and 14.8 mJy/beam at 450 microns.
We thank Callie Matulonis and Iain Coulson for the prompt support of these observations that were taken under project M16AP005.
GCN Circular #19152
A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), T. Kruehler (MPE Garching) D. Xu (NAOC/CAS), D. Malesani (DARK/NBI), Z. Cano (U. Iceland), N.R. Tanvir (U. Leicester),M. Messa (Stockholm Univ., Oskar Klein Centre), E. Gafton (NOT, Stockholm Univ. and Oskar Klein Centre) and I. R. Losada (Nordita and Stockholm Univ.) report on behalf of a larger collaboration:
We continued the monitoring of GRB 160303A (Beardmore et al., GCN 19126) with MOSCA at the 2.5m Nordic Optical Telescope (La Palma, Spain).
On a 9x300s observation with mean epoch 2:10 UT of 5 March 2016 (37.27 hr after the burst) we detect the afterglow (Butler et al GCN19131) at a magnitude of r = 25.2 +/- 0.2, as compared to the SDSS field stars. This is consistent with the magnitude reported by GROND (Bolmer et al. GCN 19150) at a similar epoch.
Gathering the r-band data from the different GCNs (Butler et al. GCN19131; de Ugarte Postigo et al. GCN 19136; Jeong et al. GCN 19140; Im et al. GCN 19141; Klose et al. GCN 19142; de Ugarte Postigo et al. GCN 19143; Graham et al. GCN 19144; Bolmer et al. GCN 19150) the light curve seems to have been flat, or even increasing in brightness during the first 4-8 hrs after the burst. After this, the light curve begins a steep decay with alpha = 1.23 +/- 0.14 (F_nu ~ t^-alpha). This is not unlike the behaviour of other short GRBs, f.ex. GRB 130603B (de Ugarte Postigo et al. 2014 A&A 563, 62), which was interpreted as being a magnetar powered event.
GCN Circular #19154
A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), D. Malesani (DARK/NBI), T. Kruehler (MPE Garching), D. Xu (NAOC/CAS), S. Schulze (PUC, MAS), J. Hjorth (DARK/NBI), N.R. Tanvir (U. Leicester) report on behalf of a larger collaboration:
We observed the afterglow of GRB 160303A (Beardmore et al., GCN 19126; Butler et al., GCN 19131) with ESO=E2=80=99s Very Large Telescope UT2 equipped with X-shooter (Paranal Observatory, Chile). The spectra cover the range from 3000 to 18000 AA. Observations consisted of 4x1200s exposures, starting at 06:03 UT of 4 March 2016 (18.8 hr after the GRB onset).
The spectrum was obtained when the GRB was at r ~ 24.1 (Klose et al. GCN 19142) and hence the S/N is rather low, implying that no absorption feature can be identified. In spite of this, a trace can be seen in the complete UVB (3000-5600AA) and VIS (5600-10100 AA) spectra. The continuum is rather blue, as already seen from multiband photometry (Butler et al., GCN 19131; Graham et al., GCN 19144). The detection of the trace down to 3000 AA implies a redshift limit of < 2.3 (considering that the Lyman break is not within the range).
In spite of the deep spectrum, we have not been able to identify any emission feature, which could be indicative of a very faint galaxy and/or a non star forming galaxy (which would be expected for a SGRB).
We acknowledge excellent support from the Paranal staff.
GCN Circular #19160
=E2=80=8BZ. Cano (U. Iceland), A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), D. Malesani (DARK/NBI) and C. C. Thoene (IAA-CSIC) report on behalf of a larger collaboration:
We observed the field of GRB 160303A (Beardmore et al., GCN Circ. 19126) with the 10.4-m GTC telescope (OSIRIS instrument) on 2016 March 8.15 UT (+4.7 days) in SDSS filters r and i. The optical transient associated with this event (Butler et al., GCN Circ. 19131) is no longer detected. Instead, we note the presence of a nearby, extended source with an r-band (AB) magnitude of 25.8 +- 0.3, as calibrated using nearby SDSS stars.
After registering the astrometry of the GTC images against our NOT afterglow image (de Ugarte Postigo et al., GCN Circ. 19136), we find that the centroid of the extended object is offset by 1.7'' +- 0.3'' in the North-East direction. We note that the radial extent of this object nearly reaches the position of the previously detected optical transient. Using the equations from Bloom, Kulkarni & Djorgovski (2002, AJ, 123, 1111), we calculate that the chance probability of finding an object with r =3D 25.8 at a separation of 1.7'' is 14% -- small, but not negligible.
If the extended object is associated with GRB 160303A, then for a standard cosmology this angular separation corresponds to 3.2, 5.6, 7.6, 10.5 kpc for redshifts of z=3D0.1, 0.2, 0.3, 0.5, respectively. This offset is consistent with that measured for short-duration GRBs at z=3D0.2 (median offset =3D 5 kpc for a range of 0.5-75 kpc; Fong, Berger & Fox 2010, ApJ, 708, 9). Instead, if GRB 160303A is a long-duration GRB, for this offset to be consistent with those measured for LGRBs (1 kpc, Bloom, Kulkarni & Djorgovski 2002, AJ, 123, 1111; de Ugarte Postigo et al. 2012, A&A, 548, 11), it would require a redshift of z=3D0.03. The luminosity distance at this redshift implies an absolute magnitude of M_r=3D-9.8, which is roughly eight to ten magnitudes fainter than those measured for LGRB host galaxies in sample studies (Savaglio, Glazebrook & Le Borgne, ApJ, 691, 182; Kruehler et al. 2015, A&A, 581, 125). Based on this line of argument, this observation suggests that GRB 160303A may be a short-duration GRB.
We acknowledge the excellent support given by the GTC staff.
photometric redshift z = 1.01 +0.18 -0.23
of host-galaxy: A. E. Nugent et al. 2022, ApJ, 940, 57

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