Gamma-ray Burst 170306A

(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:     Mon 06 Mar 17 07:15:30 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     741220,   Seg_Num: 0
GRB_RA:          263.082d {+17h 32m 20s} (J2000),
                 263.396d {+17h 33m 35s} (current),
                 262.168d {+17h 28m 40s} (1950)
GRB_DEC:         -44.747d {-44d 44' 50"} (J2000),
                 -44.759d {-44d 45' 30"} (current),
                 -44.712d {-44d 42' 41"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       22882 [cnts]    Image_Peak=336 [image_cnts]
TRIGGER_DUR:     8.192 [sec] 
TRIGGER_INDEX:   477     E_range: 25-100 keV
BKG_INTEN:       168035 [cnts]
BKG_TIME:        25485.28 SOD {07:04:45.28} UT
BKG_DUR:         64 [sec]
GRB_DATE:        17818 TJD;    65 DOY;   17/03/06
GRB_TIME:        25572.52 SOD {07:06:12.52} UT
GRB_PHI:          13.78 [deg]
GRB_THETA:        45.85 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     7.41 [sigma]
IMAGE_SIGNIF:    7.15 [sigma]
MERIT_PARAMS:     +1  +0  +0  +3  +2  -3  +0  +1 -14  +0 
SUN_POSTN:       347.03d {+23h 08m 07s}   -5.56d {-05d 33' 24"}
SUN_DIST:         81.57 [deg]   Sun_angle= 5.6 [hr] (West of Sun)
MOON_POSTN:       86.49d {+05h 45m 57s}  +18.54d {+18d 32' 19"}
MOON_DIST:       153.65 [deg]
MOON_ILLUM:      59 [%]
GAL_COORDS:      345.17, -6.15 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      264.73,-21.43 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Coordinates.  
COMMENTS:        This Notice was delayed by more than 60 sec past the end of the trigger integration interval;  
COMMENTS:        probably due to it occurring during a Malindi downlink session.  
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 = 14.26,10.76 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 06 Mar 17 07:15:58 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     741220,   Seg_Num: 0
POINT_RA:        263.116d {+17h 32m 28s} (J2000)
POINT_DEC:       -44.741d {-44d 44' 26"} (J2000)
IMG_START_DATE:  17818 TJD;    65 DOY;   17/03/06
IMG_START_TIME:  25705.96 SOD {07:08:25.96} UT,   133.4 [sec] since BAT Trigger Time
COUNTS:          13    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        1    Max_iter_allowed= 4
ERROR_CODE:      1
COMMENTS:        SWIFT-XRT Nack Position.  
COMMENTS:        No source found in the image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 06 Mar 17 07:16:44 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     741220,   Seg_Num: 0
GRB_RA:          263.082d {+17h 32m 20s} (J2000),
                 263.396d {+17h 33m 35s} (current),
                 262.168d {+17h 28m 40s} (1950)
GRB_DEC:         -44.747d {-44d 44' 50"} (J2000),
                 -44.759d {-44d 45' 30"} (current),
                 -44.712d {-44d 42' 41"} (1950)
GRB_DATE:        17818 TJD;    65 DOY;   17/03/06
GRB_TIME:        25572.52 SOD {07:06:12.52} UT
TRIGGER_INDEX:   477
GRB_PHI:          13.78 [deg]
GRB_THETA:        45.85 [deg]
DELTA_TIME:      77.00 [sec]
TRIGGER_DUR:     8.192 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     7.41 [sigma]
IMAGE_SIGNIF:    7.15 [sigma]
LC_URL:          sw00741220000msb.lc
SUN_POSTN:       347.03d {+23h 08m 07s}   -5.56d {-05d 33' 23"}
SUN_DIST:         81.57 [deg]   Sun_angle= 5.6 [hr] (West of Sun)
MOON_POSTN:       86.50d {+05h 46m 00s}  +18.54d {+18d 32' 22"}
MOON_DIST:       153.65 [deg]
MOON_ILLUM:      59 [%]
GAL_COORDS:      345.17, -6.15 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      264.73,-21.43 [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 = 14.26,10.76 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 06 Mar 17 07:19:27 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     741220,   Seg_Num: 0
GRB_RA:          263.0688d {+17h 32m 16.51s} (J2000),
                 263.3830d {+17h 33m 31.92s} (current),
                 262.1548d {+17h 28m 37.14s} (1950)
GRB_DEC:         -44.7480d {-44d 44' 52.7"} (J2000),
                 -44.7593d {-44d 45' 33.4"} (current),
                 -44.7122d {-44d 42' 43.9"} (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:  17818 TJD;    65 DOY;   17/03/06
IMG_START_TIME:  25741.00 SOD {07:09:01.00} UT,   168.5 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       347.03d {+23h 08m 08s}   -5.56d {-05d 33' 20"}
SUN_DIST:         81.58 [deg]   Sun_angle= 5.6 [hr] (West of Sun)
MOON_POSTN:       86.53d {+05h 46m 06s}  +18.54d {+18d 32' 28"}
MOON_DIST:       153.65 [deg]
MOON_ILLUM:      59 [%]
GAL_COORDS:      345.16, -6.14 [deg] galactic lon,lat of the burst
ECL_COORDS:      264.72,-21.44 [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:     Mon 06 Mar 17 07:21:27 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     741220,   Seg_Num: 0
POINT_RA:        263.117d {+17h 32m 28s} (J2000)
POINT_DEC:       -44.740d {-44d 44' 24"} (J2000)
POINT_ROLL:      89.698d
IMG_START_DATE:  17818 TJD;    65 DOY;   17/03/06
IMG_START_TIME:  25712.18 SOD {07:08:32.18} UT,   139.7 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        7.191
N_STARS:         190
X_OFFSET:        344 [pixels]
Y_OFFSET:        700 [pixels]
X_MAX:           1303 [pixels]
Y_MAX:           1659 [pixels]
DET_THRESH:      23
PHOTO_THRESH:    14
SL_URL:          sw00741220000msufc0139.fits
SUN_POSTN:       347.03d {+23h 08m 08s}   -5.56d {-05d 33' 18"}
SUN_DIST:         81.55 [deg]   Sun_angle= 5.6 [hr] (West of Sun)
MOON_POSTN:       86.55d {+05h 46m 11s}  +18.54d {+18d 32' 32"}
MOON_DIST:       153.66 [deg]
MOON_ILLUM:      59 [%]
GAL_COORDS:      345.19, -6.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      264.75,-21.43 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 06 Mar 17 07:21:27 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     741220,   Seg_Num: 0
POINT_RA:        263.117d {+17h 32m 28s} (J2000)
POINT_DEC:       -44.740d {-44d 44' 24"} (J2000)
POINT_ROLL:      89.698d
IMG_START_DATE:  17818 TJD;    65 DOY;   17/03/06
IMG_START_TIME:  25712.18 SOD {07:08:32.18} UT,   139.7 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        7.191
N_STARS:         190
X_OFFSET:        344 [pixels]
Y_OFFSET:        700 [pixels]
X_MAX:           1303 [pixels]
Y_MAX:           1659 [pixels]
DET_THRESH:      23
PHOTO_THRESH:    14
SL_URL:          sw00741220000msufc0139.fits
SUN_POSTN:       347.03d {+23h 08m 08s}   -5.56d {-05d 33' 18"}
SUN_DIST:         81.55 [deg]   Sun_angle= 5.6 [hr] (West of Sun)
MOON_POSTN:       86.55d {+05h 46m 11s}  +18.54d {+18d 32' 32"}
MOON_DIST:       153.66 [deg]
MOON_ILLUM:      59 [%]
GAL_COORDS:      345.19, -6.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      264.75,-21.43 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 06 Mar 17 07:21:54 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     741220,   Seg_Num: 0
POINT_RA:        263.117d {+17h 32m 28s} (J2000)
POINT_DEC:       -44.740d {-44d 44' 24"} (J2000)
POINT_ROLL:      89.698d
IMG_START_DATE:  17818 TJD;    65 DOY;   17/03/06
IMG_START_TIME:  25712.18 SOD {07:08:32.18} UT,   139.7 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        7.191
N_STARS:         190
X_OFFSET:        344 [pixels]
Y_OFFSET:        700 [pixels]
X_MAX:           1303 [pixels]
Y_MAX:           1659 [pixels]
DET_THRESH:      23
PHOTO_THRESH:    14
SL_URL:          sw00741220000msufc0139.fits
SUN_POSTN:       347.03d {+23h 08m 08s}   -5.56d {-05d 33' 18"}
SUN_DIST:         81.55 [deg]   Sun_angle= 5.6 [hr] (West of Sun)
MOON_POSTN:       86.55d {+05h 46m 12s}  +18.54d {+18d 32' 33"}
MOON_DIST:       153.66 [deg]
MOON_ILLUM:      59 [%]
GAL_COORDS:      345.19, -6.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      264.75,-21.43 [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:     Mon 06 Mar 17 07:23:13 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     741220,   Seg_Num: 0
POINT_RA:        263.117d {+17h 32m 28s} (J2000)
POINT_DEC:       -44.740d {-44d 44' 24"} (J2000)
ROLL:            89.698d
IMG_START_DATE:  17818 TJD;    65 DOY;   17/03/06
IMG_START_TIME:  25712.18 SOD {07:08:32.18} UT,   139.7 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     510476930
X_OFFSET:        663 [pixels]
Y_OFFSET:        1019 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       823
Y_GRB_POS:       1179
BINNING_INDEX:   1
IM_URL:          sw00741220000msuni0158.fits
SUN_POSTN:       347.03d {+23h 08m 08s}   -5.55d {-05d 33' 16"}
SUN_DIST:         81.55 [deg]   Sun_angle= 5.6 [hr] (West of Sun)
MOON_POSTN:       86.56d {+05h 46m 16s}  +18.54d {+18d 32' 36"}
MOON_DIST:       153.66 [deg]
MOON_ILLUM:      59 [%]
GAL_COORDS:      345.19, -6.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      264.75,-21.43 [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:     Mon 06 Mar 17 07:23:32 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     741220,   Seg_Num: 0
POINT_RA:        263.117d {+17h 32m 28s} (J2000)
POINT_DEC:       -44.740d {-44d 44' 24"} (J2000)
ROLL:            89.698d
IMG_START_DATE:  17818 TJD;    65 DOY;   17/03/06
IMG_START_TIME:  25712.18 SOD {07:08:32.18} UT,   139.7 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     510476930
X_OFFSET:        663 [pixels]
Y_OFFSET:        1019 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       823
Y_GRB_POS:       1179
BINNING_INDEX:   1
IM_URL:          sw00741220000msuni0158.fits
SUN_POSTN:       347.03d {+23h 08m 08s}   -5.55d {-05d 33' 16"}
SUN_DIST:         81.55 [deg]   Sun_angle= 5.6 [hr] (West of Sun)
MOON_POSTN:       86.57d {+05h 46m 16s}  +18.54d {+18d 32' 37"}
MOON_DIST:       153.66 [deg]
MOON_ILLUM:      59 [%]
GAL_COORDS:      345.19, -6.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      264.75,-21.43 [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:     Mon 06 Mar 17 07:26:07 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     741220,   Seg_Num: 0
POINT_RA:        263.118d {+17h 32m 28s} (J2000)
POINT_DEC:       -44.739d {-44d 44' 18"} (J2000)
POINT_ROLL:      89.698d
IMG_START_DATE:  17818 TJD;    65 DOY;   17/03/06
IMG_START_TIME:  25870.51 SOD {07:11:10.51} UT,   298.0 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        3.844
N_STARS:         190
X_OFFSET:        104 [pixels]
Y_OFFSET:        460 [pixels]
X_MAX:           1543 [pixels]
Y_MAX:           1899 [pixels]
DET_THRESH:      16
PHOTO_THRESH:    9
SL_URL:          sw00741220000msufc0297.fits
SUN_POSTN:       347.04d {+23h 08m 09s}   -5.55d {-05d 33' 13"}
SUN_DIST:         81.55 [deg]   Sun_angle= 5.6 [hr] (West of Sun)
MOON_POSTN:       86.59d {+05h 46m 23s}  +18.55d {+18d 32' 42"}
MOON_DIST:       153.66 [deg]
MOON_ILLUM:      59 [%]
GAL_COORDS:      345.19, -6.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      264.75,-21.42 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 06 Mar 17 07:26:07 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     741220,   Seg_Num: 0
POINT_RA:        263.118d {+17h 32m 28s} (J2000)
POINT_DEC:       -44.739d {-44d 44' 18"} (J2000)
POINT_ROLL:      89.698d
IMG_START_DATE:  17818 TJD;    65 DOY;   17/03/06
IMG_START_TIME:  25870.51 SOD {07:11:10.51} UT,   298.0 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        3.844
N_STARS:         190
X_OFFSET:        104 [pixels]
Y_OFFSET:        460 [pixels]
X_MAX:           1543 [pixels]
Y_MAX:           1899 [pixels]
DET_THRESH:      16
PHOTO_THRESH:    9
SL_URL:          sw00741220000msufc0297.fits
SUN_POSTN:       347.04d {+23h 08m 09s}   -5.55d {-05d 33' 13"}
SUN_DIST:         81.55 [deg]   Sun_angle= 5.6 [hr] (West of Sun)
MOON_POSTN:       86.59d {+05h 46m 23s}  +18.55d {+18d 32' 42"}
MOON_DIST:       153.66 [deg]
MOON_ILLUM:      59 [%]
GAL_COORDS:      345.19, -6.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      264.75,-21.42 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 06 Mar 17 07:26:35 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     741220,   Seg_Num: 0
POINT_RA:        263.118d {+17h 32m 28s} (J2000)
POINT_DEC:       -44.739d {-44d 44' 18"} (J2000)
POINT_ROLL:      89.698d
IMG_START_DATE:  17818 TJD;    65 DOY;   17/03/06
IMG_START_TIME:  25870.51 SOD {07:11:10.51} UT,   298.0 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        3.844
N_STARS:         190
X_OFFSET:        104 [pixels]
Y_OFFSET:        460 [pixels]
X_MAX:           1543 [pixels]
Y_MAX:           1899 [pixels]
DET_THRESH:      16
PHOTO_THRESH:    9
SL_URL:          sw00741220000msufc0297.fits
SUN_POSTN:       347.04d {+23h 08m 09s}   -5.55d {-05d 33' 13"}
SUN_DIST:         81.55 [deg]   Sun_angle= 5.6 [hr] (West of Sun)
MOON_POSTN:       86.60d {+05h 46m 24s}  +18.55d {+18d 32' 43"}
MOON_DIST:       153.66 [deg]
MOON_ILLUM:      59 [%]
GAL_COORDS:      345.19, -6.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      264.75,-21.42 [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:     Mon 06 Mar 17 07:27:46 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     741220,   Seg_Num: 0
POINT_RA:        263.118d {+17h 32m 28s} (J2000)
POINT_DEC:       -44.739d {-44d 44' 18"} (J2000)
ROLL:            89.698d
IMG_START_DATE:  17818 TJD;    65 DOY;   17/03/06
IMG_START_TIME:  25870.51 SOD {07:11:10.51} UT,   298.0 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     510477089
X_OFFSET:        663 [pixels]
Y_OFFSET:        1019 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       823
Y_GRB_POS:       1179
BINNING_INDEX:   1
IM_URL:          sw00741220000msuni0316.fits
SUN_POSTN:       347.04d {+23h 08m 09s}   -5.55d {-05d 33' 12"}
SUN_DIST:         81.55 [deg]   Sun_angle= 5.6 [hr] (West of Sun)
MOON_POSTN:       86.61d {+05h 46m 27s}  +18.55d {+18d 32' 46"}
MOON_DIST:       153.66 [deg]
MOON_ILLUM:      59 [%]
GAL_COORDS:      345.19, -6.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      264.75,-21.42 [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:     Mon 06 Mar 17 07:28:03 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     741220,   Seg_Num: 0
POINT_RA:        263.118d {+17h 32m 28s} (J2000)
POINT_DEC:       -44.739d {-44d 44' 18"} (J2000)
ROLL:            89.698d
IMG_START_DATE:  17818 TJD;    65 DOY;   17/03/06
IMG_START_TIME:  25870.51 SOD {07:11:10.51} UT,   298.0 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     510477089
X_OFFSET:        663 [pixels]
Y_OFFSET:        1019 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       823
Y_GRB_POS:       1179
BINNING_INDEX:   1
IM_URL:          sw00741220000msuni0316.fits
SUN_POSTN:       347.04d {+23h 08m 09s}   -5.55d {-05d 33' 12"}
SUN_DIST:         81.55 [deg]   Sun_angle= 5.6 [hr] (West of Sun)
MOON_POSTN:       86.61d {+05h 46m 27s}  +18.55d {+18d 32' 46"}
MOON_DIST:       153.66 [deg]
MOON_ILLUM:      59 [%]
GAL_COORDS:      345.19, -6.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      264.75,-21.42 [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 #20819
C. B. Markwardt (NASA/GSFC), V. D'Elia (ASDC), J. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC), A. Melandri (INAF-OAB) and K. L. Page (U Leicester) report on behalf of the Swift Team:
At 07:06:12 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 170306A (trigger=741220). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 263.082, -44.747 which is
```
   RA(J2000) = 17h 32m 20s
   Dec(J2000) = -44d 44' 50"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 20 sec. The peak count rate was ~1000 counts/sec (15-350 keV), at ~5 sec after the trigger.
The XRT began observing the field at 07:08:26.0 UT, 133.5 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source located at RA, Dec 263.06892, -44.74808 which is equivalent to:
```
   RA(J2000)  = 17h 32m 16.54s
   Dec(J2000) = -44d 44' 53.1"
```
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This location is 33 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 3.82 x 10^21 cm^-2 (Willingale et al. 2013).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 139 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. Because of the density of catalogued stars, further analysis is required to report an upper limit for any afterglow in the sub-image. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. Because of the density of catalogued stars, further analysis is required to report an upper limit for any afterglow in the region. No correction has been made for the expected extinction corresponding to E(B-V) of 0.41.
Burst Advocate for this burst is C. B. Markwardt (Craig.Markwardt AT nasa.gov). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.)
GCN Circular #20820
C. Guidorzi (U. Ferrara), S. Kobayashi, I.A. Steele (LJMU), A. Gomboc (U. Nova Gorica), C.G. Mundell (U. Bath) on behalf of a large collaboration report:
We observed Swift GRB 170306A (Markwardt et al. GCN 20819) on March 6, 07:26:06 UT (~20 minutes since the GRB trigger time) with the 1-m LCO unit in Cerro Tololo with SDSS r and i filters. Within the Swift XRT error circle we detect an uncatalogued source at the following position:
```
RA(J2000) = 17:32:16.76
Dec(J2000)= -44:44:53.7
```
with an error radius of 1". We find the following magnitude values as calibrated against nearby USNOB-1 objects (R2 and I values):
```
Mid Time      Exposure       Filter       Magnitude (AB)
(min)           (s)
-------------------------------------------------------
24            5x60           SDSS-I        18.5 +- 0.2
34            5x60           SDSS-R        19.0 +- 0.2
-------------------------------------------------------
```
At the moment we cannot make any statement on the temporal behaviour of the source. The expected Galactic dust extinction is A_r=1~mag, A_i=0.7 mag (from Schlafly et al. 2011). Given the crowded field, we caution that the source might be unrelated to the GRB.
GCN Circular #20822
Patricia Schady, Phil Wiseman (both MPE) and Jan Bolmer (ESO, Santiago) report:
We observed the field of GRB 170306A (Swift trigger 741220; Markwardt et al., GCN #20819) simultaneously in g=EF=BF=BDr=EF=BF=BDi=EF=BF=BDz=EF=BF=BD= JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla Observatory (Chile).
Observations started at 07:20 UT on 2017-03-06, 14 minutes after the GRB trigger, and they continued for ~2 hours, until the start of astronomical twilight. They were performed at an average seeing of 1.3" and at an average airmass of 1.5.
Within the 3.7" XRT error circle (Markwardt et al., GCN #20819) we detect two uncatalogued sources in addition to the source reported by Guidorzi et al. (GCN #20820). These two newly identified sources have AB magnitudes r=EF=BF=BD~20.0 mag and r=EF=BF=BD~20.3 mag calibrated against GROND zeropoints and uncorrected for the significant Galactic foreground extinction along the line of sight. None of the sources within the XRT error circle show any significant variability during the 2 hours of GROND observations.
We acknowledge the excellent support provided by the Chilean observer at the telescope, and the support astronomer, Angela Hempel, in obtaining these data.
GCN Circular #20823
S.W.K. Emery (UCL-MSSL) and C. B. Markwardt (NASA/GSFC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 170306A 140 s after the BAT trigger (Markwardt et al., GCN Circ. 20819). No optical afterglow consistent with the XRT position (Markwardt et al., GCN Circ. 20819) and the optical positions (Guidorzi et al., GCN Circ. 20820; Schady et al., GCN Circ. 20822) 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           140          290          147         >20.0
u_FC               299          548          246         >18.9
white              140          771          186         >20.4
v                  629          821           39         >18.1
b                  554          747           39         >18.6
u                  299          722          265         >19.0
w1                 678          870           39         >18.1
m2                 653          846           39         >19.0
w2                 604          796           39         >18.1
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.41 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #20828
P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), S.L. Gibson (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester) and report on behalf of the Swift-XRT team: report on behalf of the Swift-XRT team:
We have analysed 6.7 ks of XRT data for GRB 170306A, from 119 s to 28.8 ks after the BAT trigger. The data comprise 29 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 refined XRT position is RA, Dec = 263.0690, -44.7482 which is equivalent to:
```
RA (J2000): 17 32 16.56
Dec(J2000): -44 44 53.5
```
with an uncertainty of 3.6 arcsec (radius, 90% confidence).
The light curve can be modelled with an initial power-law decay with an index of alpha=3.25 (+0.28, -0.21), followed by a break at T+559 s to an alpha of 0.36 (+0.10, -0.26).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.05 (+0.30, -0.19). The best-fitting absorption column is 3.98 (+1.64, -0.16) x 10^21 cm^-2, consistent with the Galactic value of 3.8 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.8 x 10^-11 (6.1 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     3.98 (+1.64, -0.16) x 10^21 cm^-2
Galactic foreground: 3.8 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:	     2.05 (+0.30, -0.19)
```
If the light curve continues to decay with a power-law decay index of 0.36, the count rate at T+24 hours will be 0.011 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.3 x 10^-13 (6.9 x 10^-13) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00741220.
This circular is an official product of the Swift-XRT team.
GCN Circular #20829
T. Sakamoto (AGU), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), N. Gehrels (GSFC), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 170306A (trigger #741220) (Markwardt et al., GCN Circ. 20819). The BAT ground-calculated position is RA, Dec = 263.087, -44.765 deg which is
```
   RA(J2000)  =  17h 32m 20.9s
   Dec(J2000) = -44d 45' 52.5"
```
with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 29%.
The mask-weighted light curve shows a pulse that starts at ~T-7 s and ends at ~T+20 s. In addition, there is a hint of some weak emissions from ~T-100 s to ~T-80 s. T90 (15-350 keV) is 17.8 +- 6.7 sec (estimated error including systematics).
The time-averaged spectrum from T-7.1 to T+19.7 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.98 +- 0.28. The fluence in the 15-150 keV band is 8.3 +- 1.4 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+10.93 sec in the 15-150 keV band is 1.3 +- 0.4 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/741220/BA/
GCN Circular #20843
Patricia Schady (MPE Garching) reports:
Following on from the GROND (Greiner et al. 2008, PASP 120, 405) observations of GRB 170306A on the 2017-03-06 (Schady et al., GCN #20819), I re-observed the field simultaneously in g'r'i'z'JHK with GROND at on 2017-03-10, 4 days after the GRB trigger. Observations were performed at an average seeing of 1.4" and at an average airmass of 1.7.
One of the three sources detected with GROND (Schady et al., GCN #20819) within the refined XRT error circle (D=EF=BF=BDAvanzo et al., GCN #20828) is no longer seen in the latest GROND observations down to the following 3 sigma limiting magnitudes (all in AB system):
```
g' > 22.6 mag
r' >  23.5 mag
i' > 22.3 mag
z' > 22.4 mag
J > 20.4 mag
H > 19.9 mag
K > 18.9 mag
```
This source is therefore the likely optical/NIR afterglow of GRB 170306A. The position of the afterglow candidate is
```
RA (J2000)    = 17:32:16.69
Dec (J2000) =  -44:44:55.5
```
with a positional uncertainty of 0.3" in both coordinates.
Based on combined images with 36 min of total integration time in g'r'i'z' and 30 min in JHK at a mid-time of 09:33 UT on 2017-03-06, the afterglow candidate had the following preliminary magnitudes (all in AB system):
```
g' = 21.6 +/- 0.1 mag
r' = 20.4 +/- 0.1 mag
i'= 20.0 +/- 0.1 mag
z' = 19.9 +/- 0.1 mag
J = 19.1 +/- 0.1 mag
H = 18.4 +/- 0.1 mag
K = 18.5 +/- 0.2 mag
```
The given magnitudes are derived based on images calibrated against GROND zero points in the optical and 2MASS field stars in the NIR bands. They are not corrected for the Galactic foreground extinction corresponding to a reddening of E_(B-V)=3D 0.36 in the direction of the burst (Schlafly & Finkbeiner 2011).
I acknowledge the excellent support provided by the Chilean observer at the telescope, and the support astronomer, Sam Kim, in obtaining these data. I also thank David Buckley for some useful email exchanges that in part led to the second epoch of GROND observations.
GCN Circular #20844
D.A.H. Buckley (SAAO/SALT), A, Martin-Carrillo (U. College Dublin), S. Razzaque (U. Johannesburg) and R. Skelton (SAAO/SALT) report on behalf of a larger collaboration.
We observed the nominal position of GRB 170306A (Markwardt et al. GCN 20819 and Guidorzi et al. GCN 20820) on 2017-03-07 at 01:22:42 UTC using the Southern African Large Telescope (SALT) in Sutherland, South Africa, 18.61 h after the Swift GRB trigger. A 20 sec r'-band image was obtained using SALTICAM just prior to the commencement of attempted low resolution (R ~ 355 at 660 nm) spectroscopy. Two stellar objects at r=E2=80=99 ~ 19 and 20 were seen, with FWHM of 1.7 arcsec, near the GRB position and long slit spectroscopy was attempted of both. Only the brighter one provided a detection, which was noisy and showed no obvious spectral features. Subsequent information provided by P. Schady on possible optical candidates from the first GROND observation (Schady et al. GCN 20822) was used to confirm the identification of the r=E2=80=99 =3D 20.4 object identified by Schady (GCN 20843) as the optical counterpart. The SALT image shows a very weak detection of this object, barely above the background, with an estimated brightness of r=E2=80= =99=3D 21.4 +/- 0.3, having dimmed approximately one magnitude since detection.
We thank Patricia Schady and Christiano Guidorzi for providing information = to assist in the identification of the optical counterpart.

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Jochen Greiner, last update: 10-Mar-2017 [Disclaimer]