Gamma-ray Burst 110731A

(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:     Sun 31 Jul 11 11:09:53 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     458448,   Seg_Num: 0
GRB_RA:          280.521d {+18h 42m 05s} (J2000),
                 280.704d {+18h 42m 49s} (current),
                 279.731d {+18h 38m 56s} (1950)
GRB_DEC:         -28.546d {-28d 32' 44"} (J2000),
                 -28.534d {-28d 32' 02"} (current),
                 -28.595d {-28d 35' 40"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       12883 [cnts]    Image_Peak=2317 [image_cnts]
TRIGGER_DUR:     1.024 [sec] 
TRIGGER_INDEX:   146     E_range: 25-100 keV
BKG_INTEN:       21612 [cnts]
BKG_TIME:        40152.78 SOD {11:09:12.78} UT
BKG_DUR:         8 [sec]
GRB_DATE:        15773 TJD;   212 DOY;   11/07/31
GRB_TIME:        40170.45 SOD {11:09:30.45} UT
GRB_PHI:         175.32 [deg]
GRB_THETA:        16.25 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     180.74 [sigma]
IMAGE_SIGNIF:    24.57 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +2  +8  +0  +1 +87  +0 
SUN_POSTN:       130.33d {+08h 41m 20s}  +18.29d {+18d 17' 15"}
SUN_DIST:        151.04 [deg]   Sun_angle= -10.0 [hr] (East of Sun)
MOON_POSTN:      138.25d {+09h 13m 01s}  +11.80d {+11d 48' 12"}
MOON_DIST:       141.22 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:        6.22,-10.72 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      279.27, -5.44 [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 = 150.61,-4.56 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sun 31 Jul 11 11:09:47 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      46
TRIGGER_NUM:     333803371
GRB_RA:          281.800d {+18h 47m 12s} (J2000),
                 281.999d {+18h 48m 00s} (current),
                 280.939d {+18h 43m 45s} (1950)
GRB_DEC:         -38.933d {-38d 55' 59"} (J2000),
                 -38.920d {-38d 55' 11"} (current),
                 -38.988d {-38d 59' 16"} (1950)
GRB_ERROR:       4.30 [deg radius, statistical plus systematic]
GRB_INTEN:       980 [cnts/sec]
DATA_SIGNIF:     40.80 [sigma]
INTEG_TIME:      1.024 [sec]
GRB_DATE:        15773 TJD;   212 DOY;   11/07/31
GRB_TIME:        40169.94 SOD {11:09:29.94} UT
GRB_PHI:          60.00 [deg]
GRB_THETA:        10.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO:      1.02
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      92%  GRB
2nd_MOST_LIKELY:   5%  SGR_1806n20
DETECTORS:       1,0,0, 1,0,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       130.33d {+08h 41m 20s}  +18.29d {+18d 17' 15"}
SUN_DIST:        147.93 [deg]   Sun_angle= -10.1 [hr] (East of Sun)
MOON_POSTN:      138.25d {+09h 13m 00s}  +11.80d {+11d 48' 13"}
MOON_DIST:       137.96 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:      356.89,-15.89 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      279.52,-15.88 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 183.57,18.60 [deg].

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sun 31 Jul 11 11:09:56 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      60
TRIGGER_NUM:     333803371
GRB_RA:          281.983d {+18h 47m 56s} (J2000),
                 282.183d {+18h 48m 44s} (current),
                 281.122d {+18h 44m 29s} (1950)
GRB_DEC:         -38.983d {-38d 58' 59"} (J2000),
                 -38.970d {-38d 58' 10"} (current),
                 -39.039d {-39d 02' 20"} (1950)
GRB_ERROR:       4.42 [deg radius, statistical plus systematic]
GRB_INTEN:       863 [cnts/sec]
DATA_SIGNIF:     69.90 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        15773 TJD;   212 DOY;   11/07/31
GRB_TIME:        40169.94 SOD {11:09:29.94} UT
GRB_PHI:          60.00 [deg]
GRB_THETA:        10.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      0.78
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      95%  GRB
2nd_MOST_LIKELY:   2%  SGR_1806n20
DETECTORS:       1,0,0, 1,0,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       130.33d {+08h 41m 20s}  +18.29d {+18d 17' 15"}
SUN_DIST:        148.02 [deg]   Sun_angle= -10.1 [hr] (East of Sun)
MOON_POSTN:      138.25d {+09h 13m 01s}  +11.80d {+11d 48' 11"}
MOON_DIST:       138.05 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:      356.90,-16.04 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      279.66,-15.95 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 183.57,18.60 [deg].  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(1.0<100sec) coincident with the SWIFT_BAT event (trignum=458448).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 31 Jul 11 11:11:12 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     458448,   Seg_Num: 0
GRB_RA:          280.5042d {+18h 42m 01.00s} (J2000),
                 280.6870d {+18h 42m 44.87s} (current),
                 279.7145d {+18h 38m 51.47s} (1950)
GRB_DEC:         -28.5363d {-28d 32' 10.6"} (J2000),
                 -28.5244d {-28d 31' 28.0"} (current),
                 -28.5852d {-28d 35' 06.6"} (1950)
GRB_ERROR:       4.8 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       5.84e-09 [erg/cm2/sec]
GRB_SIGNIF:      12.08 [sigma]
IMG_START_DATE:  15773 TJD;   212 DOY;   11/07/31
IMG_START_TIME:  40236.85 SOD {11:10:36.85} UT,   66.4 [sec] since BAT Trigger Time
TAM[0-3]:        327.67 237.23 261.58 243.60
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       130.33d {+08h 41m 20s}  +18.29d {+18d 17' 14"}
SUN_DIST:        151.03 [deg]   Sun_angle= -10.0 [hr] (East of Sun)
MOON_POSTN:      138.27d {+09h 13m 04s}  +11.80d {+11d 47' 55"}
MOON_DIST:       141.19 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:        6.22,-10.70 [deg] galactic lon,lat of the burst
ECL_COORDS:      279.26, -5.43 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 1.07 arcmin from the BAT position.  
COMMENTS:        The object found at this position is either a very bright burst or a cosmic ray hit.  
COMMENTS:        Examine the XRT Image to differentiate (CRs are much more compact); see examples at:  
COMMENTS:        http://www.swift.psu.edu/xrt/XRT_Postage_Stamp_Image_Photo_Gallery.htm .

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 31 Jul 11 11:11:27 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     458448,   Seg_Num: 0
GRB_RA:          280.5042d {+18h 42m 01.0s} (J2000),
                 280.6870d {+18h 42m 44.8s} (current),
                 279.7145d {+18h 38m 51.4s} (1950)
GRB_DEC:         -28.5363d {-28d 32' 10.6"} (J2000),
                 -28.5244d {-28d 31' 28.0"} (current),
                 -28.5852d {-28d 35' 06.6"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       146 [cnts]
IMG_START_DATE:  15773 TJD;   212 DOY;   11/07/31
IMG_START_TIME:  40236.85 SOD {11:10:36.85} UT,   66.4 [sec] since BAT Trigger Time
CENTROID_X:      293.82,  raw= 294  [pixels]
CENTROID_Y:      283.88,  raw= 284  [pixels]
ROLL:            255.95 [deg]
GAIN:            2
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -33.28
GRB_POS_XRT_Z:   -23.28
IMAGE_URL:       sw00458448000msxps_rw.img
SUN_POSTN:       130.33d {+08h 41m 20s}  +18.29d {+18d 17' 14"}
SUN_DIST:        151.03 [deg]   Sun_angle= -10.0 [hr] (East of Sun)
MOON_POSTN:      138.27d {+09h 13m 04s}  +11.80d {+11d 47' 52"}
MOON_DIST:       141.19 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:        6.22,-10.70 [deg] galactic lon,lat of the burst
ECL_COORDS:      279.26, -5.43 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 31 Jul 11 11:11:22 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     458448,   Seg_Num: 0
GRB_RA:          280.5042d {+18h 42m 01.0s} (J2000),
                 280.6870d {+18h 42m 44.8s} (current),
                 279.7145d {+18h 38m 51.4s} (1950)
GRB_DEC:         -28.5363d {-28d 32' 10.6"} (J2000),
                 -28.5244d {-28d 31' 28.0"} (current),
                 -28.5852d {-28d 35' 06.6"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       146 [cnts]
IMG_START_DATE:  15773 TJD;   212 DOY;   11/07/31
IMG_START_TIME:  40236.85 SOD {11:10:36.85} UT,   66.4 [sec] since BAT Trigger Time
CENTROID_X:      293.82,  raw= 294  [pixels]
CENTROID_Y:      283.88,  raw= 284  [pixels]
ROLL:            255.95 [deg]
GAIN:            2
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -33.28
GRB_POS_XRT_Z:   -23.28
IMAGE_URL:       sw00458448000msxps_rw.img
SUN_POSTN:       130.33d {+08h 41m 20s}  +18.29d {+18d 17' 14"}
SUN_DIST:        151.03 [deg]   Sun_angle= -10.0 [hr] (East of Sun)
MOON_POSTN:      138.27d {+09h 13m 04s}  +11.80d {+11d 47' 53"}
MOON_DIST:       141.19 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:        6.22,-10.70 [deg] galactic lon,lat of the burst
ECL_COORDS:      279.26, -5.43 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sun 31 Jul 11 11:12:06 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      70
TRIGGER_NUM:     333803371
GRB_RA:          281.090d {+18h 44m 22s} (J2000),
                 281.270d {+18h 45m 05s} (current),
                 280.312d {+18h 41m 15s} (1950)
GRB_DEC:         -26.660d {-26d 39' 35"} (J2000),
                 -26.648d {-26d 38' 50"} (current),
                 -26.712d {-26d 42' 41"} (1950)
GRB_ERROR:       1.00 [deg radius, statistical only]
DATA_SIGNIF:     89.30 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        15773 TJD;   212 DOY;   11/07/31
GRB_TIME:        40169.94 SOD {11:09:29.94} UT
GRB_PHI:         302.00 [deg]
GRB_THETA:         4.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4143 (Gnd S/W Version number)
SUN_POSTN:       130.33d {+08h 41m 20s}  +18.29d {+18d 17' 13"}
SUN_DIST:        151.95 [deg]   Sun_angle= -10.1 [hr] (East of Sun)
MOON_POSTN:      138.27d {+09h 13m 06s}  +11.80d {+11d 47' 44"}
MOON_DIST:       142.22 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:        8.18,-10.37 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      279.92, -3.60 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        In the LAT Field-of-view.  
COMMENTS:        Bright hard burst in the GBM.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sun 31 Jul 11 11:12:00 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      58
TRIGGER_NUM:     333803371
GRB_RA:          283.110d {+18h 52m 26s} (J2000),
                 283.301d {+18h 53m 12s} (current),
                 282.286d {+18h 49m 09s} (1950)
GRB_DEC:         -34.060d {-34d 03' 35"} (J2000),
                 -34.045d {-34d 02' 42"} (current),
                 -34.121d {-34d 07' 15"} (1950)
GRB_ERROR:       1.00 [deg radius, statistical only]
DATA_SIGNIF:     82.20 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        15773 TJD;   212 DOY;   11/07/31
GRB_TIME:        40169.94 SOD {11:09:29.94} UT
GRB_PHI:          58.00 [deg]
GRB_THETA:         5.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4143 (Gnd S/W Version number)
SUN_POSTN:       130.33d {+08h 41m 20s}  +18.29d {+18d 17' 13"}
SUN_DIST:        151.22 [deg]   Sun_angle= -10.2 [hr] (East of Sun)
MOON_POSTN:      138.27d {+09h 13m 05s}  +11.80d {+11d 47' 45"}
MOON_DIST:       141.18 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:        1.98,-14.99 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      281.04,-11.12 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        In the LAT Field-of-view.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 31 Jul 11 11:13:32 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     458448,   Seg_Num: 0
GRB_RA:          280.521d {+18h 42m 05s} (J2000),
                 280.704d {+18h 42m 49s} (current),
                 279.731d {+18h 38m 56s} (1950)
GRB_DEC:         -28.546d {-28d 32' 44"} (J2000),
                 -28.534d {-28d 32' 02"} (current),
                 -28.595d {-28d 35' 40"} (1950)
GRB_DATE:        15773 TJD;   212 DOY;   11/07/31
GRB_TIME:        40170.45 SOD {11:09:30.45} UT
TRIGGER_INDEX:   146
GRB_PHI:         175.32 [deg]
GRB_THETA:        16.25 [deg]
DELTA_TIME:      -5.00 [sec]
TRIGGER_DUR:     1.024 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     180.74 [sigma]
IMAGE_SIGNIF:    24.57 [sigma]
LC_URL:          sw00458448000msb.lc
SUN_POSTN:       130.33d {+08h 41m 20s}  +18.29d {+18d 17' 13"}
SUN_DIST:        151.04 [deg]   Sun_angle= -10.0 [hr] (East of Sun)
MOON_POSTN:      138.29d {+09h 13m 09s}  +11.79d {+11d 47' 26"}
MOON_DIST:       141.18 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:        6.22,-10.72 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      279.27, -5.44 [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 = 150.61,-4.56 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 31 Jul 11 11:15:13 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     458448,   Seg_Num: 0
POINT_RA:        280.513d {+18h 42m 03s} (J2000)
POINT_DEC:       -28.544d {-28d 32' 37"} (J2000)
POINT_ROLL:      255.953d
IMG_START_DATE:  15773 TJD;   212 DOY;   11/07/31
IMG_START_TIME:  40245.46 SOD {11:10:45.46} UT,   75.0 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.447
N_STARS:         190
X_OFFSET:        424 [pixels]
Y_OFFSET:        544 [pixels]
X_MAX:           1383 [pixels]
Y_MAX:           1503 [pixels]
DET_THRESH:      18
PHOTO_THRESH:    10
SL_URL:          sw00458448000msufc0075.fits
SUN_POSTN:       130.34d {+08h 41m 21s}  +18.29d {+18d 17' 11"}
SUN_DIST:        151.03 [deg]   Sun_angle= -10.0 [hr] (East of Sun)
MOON_POSTN:      138.30d {+09h 13m 13s}  +11.78d {+11d 47' 05"}
MOON_DIST:       141.16 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:        6.22,-10.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      279.27, -5.44 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 31 Jul 11 11:15:42 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     458448,   Seg_Num: 0
POINT_RA:        280.513d {+18h 42m 03s} (J2000)
POINT_DEC:       -28.544d {-28d 32' 37"} (J2000)
POINT_ROLL:      255.953d
IMG_START_DATE:  15773 TJD;   212 DOY;   11/07/31
IMG_START_TIME:  40245.46 SOD {11:10:45.46} UT,   75.0 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.447
N_STARS:         190
X_OFFSET:        424 [pixels]
Y_OFFSET:        544 [pixels]
X_MAX:           1383 [pixels]
Y_MAX:           1503 [pixels]
DET_THRESH:      18
PHOTO_THRESH:    10
SL_URL:          sw00458448000msufc0075.fits
SUN_POSTN:       130.34d {+08h 41m 21s}  +18.29d {+18d 17' 11"}
SUN_DIST:        151.03 [deg]   Sun_angle= -10.0 [hr] (East of Sun)
MOON_POSTN:      138.31d {+09h 13m 14s}  +11.78d {+11d 46' 59"}
MOON_DIST:       141.15 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:        6.22,-10.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      279.27, -5.44 [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:     Sun 31 Jul 11 11:17:25 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     458448,   Seg_Num: 0
POINT_RA:        280.513d {+18h 42m 03s} (J2000)
POINT_DEC:       -28.544d {-28d 32' 37"} (J2000)
ROLL:            255.953d
IMG_START_DATE:  15773 TJD;   212 DOY;   11/07/31
IMG_START_TIME:  40245.46 SOD {11:10:45.46} UT,   75.0 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     333803452
X_OFFSET:        865 [pixels]
Y_OFFSET:        897 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1025
Y_GRB_POS:       1057
BINNING_INDEX:   1
IM_URL:          sw00458448000msuni0083.fits
SUN_POSTN:       130.34d {+08h 41m 21s}  +18.29d {+18d 17' 10"}
SUN_DIST:        151.03 [deg]   Sun_angle= -10.0 [hr] (East of Sun)
MOON_POSTN:      138.32d {+09h 13m 18s}  +11.78d {+11d 46' 38"}
MOON_DIST:       141.14 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:        6.22,-10.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      279.27, -5.44 [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:     Sun 31 Jul 11 11:18:02 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     458448,   Seg_Num: 0
POINT_RA:        280.513d {+18h 42m 03s} (J2000)
POINT_DEC:       -28.544d {-28d 32' 37"} (J2000)
ROLL:            255.953d
IMG_START_DATE:  15773 TJD;   212 DOY;   11/07/31
IMG_START_TIME:  40245.46 SOD {11:10:45.46} UT,   75.0 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     333803452
X_OFFSET:        865 [pixels]
Y_OFFSET:        897 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1025
Y_GRB_POS:       1057
BINNING_INDEX:   1
IM_URL:          sw00458448000msuni0083.fits
SUN_POSTN:       130.34d {+08h 41m 21s}  +18.29d {+18d 17' 10"}
SUN_DIST:        151.03 [deg]   Sun_angle= -10.0 [hr] (East of Sun)
MOON_POSTN:      138.33d {+09h 13m 19s}  +11.78d {+11d 46' 30"}
MOON_DIST:       141.13 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:        6.22,-10.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      279.27, -5.44 [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:     Sun 31 Jul 11 11:19:51 UT
NOTICE_TYPE:     Swift-UVOT Position
TRIGGER_NUM:     458448,   Seg_Num: 0
GRB_RA:          280.5041d {+18h 42m 00.98s} (J2000),
                 280.6869d {+18h 42m 44.85s} (current),
                 279.7144d {+18h 38m 51.45s} (1950)
GRB_DEC:         -28.5371d {-28d 32' 13.5"} (J2000),
                 -28.5252d {-28d 31' 30.8"} (current),
                 -28.5860d {-28d 35' 09.4"} (1950)
GRB_ERROR:       0.6 [arcsec radius, statistical only]
GRB_MAG:         15.80 +/- 0.14 [mag]
FILTER:          10, White
IMG_START_DATE:  15773 TJD;   212 DOY;   11/07/31
IMG_START_TIME:  40245.00 SOD {11:10:45.00} UT,   74.6 [sec] since BAT Trigger Time
SUN_POSTN:       130.34d {+08h 41m 21s}  +18.29d {+18d 17' 09"}
SUN_DIST:        151.02 [deg]   Sun_angle= -10.0 [hr] (East of Sun)
MOON_POSTN:      138.35d {+09h 13m 23s}  +11.77d {+11d 46' 08"}
MOON_DIST:       141.11 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:        6.22,-10.70 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      279.26, -5.43 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT UVOT Position Notice.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The UVOT position is 2.9 arcsec from the XRT position.  
COMMENTS:        Result based on Genie data.  
COMMENTS:        Notice generated automatically.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 31 Jul 11 11:22:05 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     458448,   Seg_Num: 0
POINT_RA:        280.514d {+18h 42m 03s} (J2000)
POINT_DEC:       -28.542d {-28d 32' 29"} (J2000)
POINT_ROLL:      255.955d
IMG_START_DATE:  15773 TJD;   212 DOY;   11/07/31
IMG_START_TIME:  40457.44 SOD {11:14:17.44} UT,   287.0 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.403
N_STARS:         190
X_OFFSET:        545 [pixels]
Y_OFFSET:        577 [pixels]
X_MAX:           1504 [pixels]
Y_MAX:           1536 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00458448000msufc0286.fits
SUN_POSTN:       130.34d {+08h 41m 22s}  +18.29d {+18d 17' 07"}
SUN_DIST:        151.03 [deg]   Sun_angle= -10.0 [hr] (East of Sun)
MOON_POSTN:      138.37d {+09h 13m 29s}  +11.76d {+11d 45' 40"}
MOON_DIST:       141.09 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:        6.22,-10.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      279.27, -5.44 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 31 Jul 11 11:22:32 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     458448,   Seg_Num: 0
POINT_RA:        280.514d {+18h 42m 03s} (J2000)
POINT_DEC:       -28.542d {-28d 32' 29"} (J2000)
POINT_ROLL:      255.955d
IMG_START_DATE:  15773 TJD;   212 DOY;   11/07/31
IMG_START_TIME:  40457.44 SOD {11:14:17.44} UT,   287.0 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.403
N_STARS:         190
X_OFFSET:        545 [pixels]
Y_OFFSET:        577 [pixels]
X_MAX:           1504 [pixels]
Y_MAX:           1536 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00458448000msufc0286.fits
SUN_POSTN:       130.34d {+08h 41m 22s}  +18.29d {+18d 17' 07"}
SUN_DIST:        151.03 [deg]   Sun_angle= -10.0 [hr] (East of Sun)
MOON_POSTN:      138.37d {+09h 13m 30s}  +11.76d {+11d 45' 34"}
MOON_DIST:       141.09 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:        6.22,-10.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      279.27, -5.44 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN Circular #12215
S. R. Oates (UCL-MSSL), A. P. Beardmore (U Leicester), S. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU), A. Melandri (INAF-OAB), C. J. Mountford (U Leicester), K. L. Page (U Leicester), D. M. Palmer (LANL), C. J. Saxton (UCL-MSSL) and T. N. Ukwatta (MSU) report on behalf of the Swift Team:
At 11:09:30 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 110731A (trigger=458448). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 280.521, -28.546 which is
```
   RA(J2000) = 18h 42m 05s
   Dec(J2000) = -28d 32' 44"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multiple-peaked structure with a duration of about 20 sec. The peak count rate was ~20000 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 11:10:36.9 UT, 66.4 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 280.5042, -28.5363 which is equivalent to:
```
   RA(J2000)  = 18h 42m 01.00s
   Dec(J2000) = -28d 32' 10.6"
```
with an uncertainty of 4.8 arcseconds (radius, 90% containment). This location is 63 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy.
UVOT took a finding chart exposure of 150 seconds with the White filter starting 75 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at
```
  RA(J2000)  =	18:42:01.01 = 280.50419
  DEC(J2000) = -28:32:13.7  = -28.53713
```
with a 90%-confidence error radius of about 0.61 arc sec. This position is 3.0 arc sec. from the center of the XRT error circle. The estimated magnitude is 15.80 with a 1-sigma error of about 0.14. No correction has been made for the expected extinction corresponding to E(B-V) of 0.17.
Burst Advocate for this burst is S. R. Oates (sro AT mssl.ucl.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 NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 31 Jul 11 11:23:36 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     458448,   Seg_Num: 0
POINT_RA:        280.514d {+18h 42m 03s} (J2000)
POINT_DEC:       -28.542d {-28d 32' 29"} (J2000)
ROLL:            255.955d
IMG_START_DATE:  15773 TJD;   212 DOY;   11/07/31
IMG_START_TIME:  40457.44 SOD {11:14:17.44} UT,   287.0 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     333803664
X_OFFSET:        865 [pixels]
Y_OFFSET:        897 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1025
Y_GRB_POS:       1057
BINNING_INDEX:   1
IM_URL:          sw00458448000msuni0294.fits
SUN_POSTN:       130.34d {+08h 41m 22s}  +18.29d {+18d 17' 06"}
SUN_DIST:        151.03 [deg]   Sun_angle= -10.0 [hr] (East of Sun)
MOON_POSTN:      138.38d {+09h 13m 32s}  +11.76d {+11d 45' 21"}
MOON_DIST:       141.08 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:        6.22,-10.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      279.27, -5.44 [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:     Sun 31 Jul 11 11:23:49 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     458448,   Seg_Num: 0
POINT_RA:        280.514d {+18h 42m 03s} (J2000)
POINT_DEC:       -28.542d {-28d 32' 29"} (J2000)
ROLL:            255.955d
IMG_START_DATE:  15773 TJD;   212 DOY;   11/07/31
IMG_START_TIME:  40457.44 SOD {11:14:17.44} UT,   287.0 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     333803664
X_OFFSET:        865 [pixels]
Y_OFFSET:        897 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1025
Y_GRB_POS:       1057
BINNING_INDEX:   1
IM_URL:          sw00458448000msuni0294.fits
SUN_POSTN:       130.34d {+08h 41m 22s}  +18.29d {+18d 17' 06"}
SUN_DIST:        151.03 [deg]   Sun_angle= -10.0 [hr] (East of Sun)
MOON_POSTN:      138.39d {+09h 13m 32s}  +11.76d {+11d 45' 18"}
MOON_DIST:       141.08 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:        6.22,-10.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      279.27, -5.44 [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:     Sun 31 Jul 11 11:29:40 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     458448,   Seg_Num: 0
POINT_RA:        280.514d {+18h 42m 03s} (J2000)
POINT_DEC:       -28.541d {-28d 32' 28"} (J2000)
POINT_ROLL:      255.955d
IMG_START_DATE:  15773 TJD;   212 DOY;   11/07/31
IMG_START_TIME:  41035.51 SOD {11:23:55.51} UT,   865.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.485
N_STARS:         190
X_OFFSET:        305 [pixels]
Y_OFFSET:        337 [pixels]
X_MAX:           1744 [pixels]
Y_MAX:           1776 [pixels]
DET_THRESH:      18
PHOTO_THRESH:    10
SL_URL:          sw00458448000msufc0865.fits
SUN_POSTN:       130.35d {+08h 41m 23s}  +18.28d {+18d 17' 03"}
SUN_DIST:        151.03 [deg]   Sun_angle= -10.0 [hr] (East of Sun)
MOON_POSTN:      138.44d {+09h 13m 46s}  +11.73d {+11d 44' 06"}
MOON_DIST:       141.02 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:        6.22,-10.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      279.27, -5.44 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 31 Jul 11 11:30:10 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     458448,   Seg_Num: 0
POINT_RA:        280.514d {+18h 42m 03s} (J2000)
POINT_DEC:       -28.541d {-28d 32' 28"} (J2000)
POINT_ROLL:      255.955d
IMG_START_DATE:  15773 TJD;   212 DOY;   11/07/31
IMG_START_TIME:  41035.51 SOD {11:23:55.51} UT,   865.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.485
N_STARS:         190
X_OFFSET:        305 [pixels]
Y_OFFSET:        337 [pixels]
X_MAX:           1744 [pixels]
Y_MAX:           1776 [pixels]
DET_THRESH:      18
PHOTO_THRESH:    10
SL_URL:          sw00458448000msufc0865.fits
SUN_POSTN:       130.35d {+08h 41m 23s}  +18.28d {+18d 17' 02"}
SUN_DIST:        151.03 [deg]   Sun_angle= -10.0 [hr] (East of Sun)
MOON_POSTN:      138.45d {+09h 13m 47s}  +11.73d {+11d 43' 59"}
MOON_DIST:       141.01 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:        6.22,-10.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      279.27, -5.44 [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:     Sun 31 Jul 11 11:30:51 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     458448,   Seg_Num: 0
GRB_RA:          280.5036d {+18h 42m 00.86s} (J2000),
                 280.6864d {+18h 42m 44.73s} (current),
                 279.7139d {+18h 38m 51.33s} (1950)
GRB_DEC:         -28.5370d {-28d 32' 13.1"} (J2000),
                 -28.5251d {-28d 31' 30.5"} (current),
                 -28.5859d {-28d 35' 09.1"} (1950)
GRB_ERROR:       2.1 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  15773 TJD;   212 DOY;   11/07/31
IMG_START_TIME:  40818.00 SOD {11:20:18.00} UT,   647.6 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       130.35d {+08h 41m 23s}  +18.28d {+18d 17' 02"}
SUN_DIST:        151.02 [deg]   Sun_angle= -10.0 [hr] (East of Sun)
MOON_POSTN:      138.45d {+09h 13m 49s}  +11.73d {+11d 43' 51"}
MOON_DIST:       141.00 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:        6.22,-10.70 [deg] galactic lon,lat of the burst
ECL_COORDS:      279.26, -5.43 [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 0.58% < P(seren) < 1.1%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 31 Jul 11 11:32:01 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     458448,   Seg_Num: 0
POINT_RA:        280.514d {+18h 42m 03s} (J2000)
POINT_DEC:       -28.541d {-28d 32' 28"} (J2000)
ROLL:            255.955d
IMG_START_DATE:  15773 TJD;   212 DOY;   11/07/31
IMG_START_TIME:  41035.51 SOD {11:23:55.51} UT,   865.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     333804242
X_OFFSET:        864 [pixels]
Y_OFFSET:        896 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1024
Y_GRB_POS:       1056
BINNING_INDEX:   1
IM_URL:          sw00458448000msuni0873.fits
SUN_POSTN:       130.35d {+08h 41m 23s}  +18.28d {+18d 17' 01"}
SUN_DIST:        151.02 [deg]   Sun_angle= -10.0 [hr] (East of Sun)
MOON_POSTN:      138.46d {+09h 13m 51s}  +11.73d {+11d 43' 36"}
MOON_DIST:       141.00 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:        6.22,-10.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      279.27, -5.44 [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:     Sun 31 Jul 11 11:32:21 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     458448,   Seg_Num: 0
POINT_RA:        280.514d {+18h 42m 03s} (J2000)
POINT_DEC:       -28.541d {-28d 32' 28"} (J2000)
ROLL:            255.955d
IMG_START_DATE:  15773 TJD;   212 DOY;   11/07/31
IMG_START_TIME:  41035.51 SOD {11:23:55.51} UT,   865.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     333804242
X_OFFSET:        864 [pixels]
Y_OFFSET:        896 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1024
Y_GRB_POS:       1056
BINNING_INDEX:   1
IM_URL:          sw00458448000msuni0873.fits
SUN_POSTN:       130.35d {+08h 41m 23s}  +18.28d {+18d 17' 01"}
SUN_DIST:        151.02 [deg]   Sun_angle= -10.0 [hr] (East of Sun)
MOON_POSTN:      138.47d {+09h 13m 52s}  +11.73d {+11d 43' 32"}
MOON_DIST:       140.99 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:        6.22,-10.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      279.27, -5.44 [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 #12216
David Bersier (LJMU) report on behalf of a larger collaboration:
The Faulkes Telescopes North (Hawaii) and South (Australia) both started automatically (110 and 182 seconds after trigger) to observe GRB 110731A, in response to the Swift trigger 458448. The software detected a uncatalogued decaying source that coincides with the position of the UVOT candidate afterglow (GCN 12215). We measure a magnitude mR=16.4 at 28 minutes after the trigger time. Assuming a power law decay, the decay index is about -1.
Observations have been obtained with the BVR filters and are continuing on both telescopes.
GCN Circular #12217
H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), C. B. Markwardt (GSFC), S. R. Oates (UCL-MSSL), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+402 sec from the recent telemetry downlink, we report further analysis of BAT GRB 110731A (trigger #458448) (Oates, et al., GCN Circ. 12215). The BAT ground-calculated position is RA, Dec = 280.513, -28.536 deg, which is
```
   RA(J2000)  =  18h 42m 03.1s 
   Dec(J2000) = -28d 32' 10.0" 
```
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 98%.
The mask-weighted light curve shows many overlapping peaks starting at ~T-1.5 sec, peaking at +T_zero, and ending at ~T+8 sec with a long exponential decay lasting out to ~T+80 sec. T90 (15-350 keV) is 38.8 +- 13.0 sec (estimated error including systematics).
The time-averaged spectrum from T-1.3 to T+80.3 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.15 +- 0.05. The fluence in the 15-150 keV band is 6.0 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T-0.26 sec in the 15-150 keV band is 11.0 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/458448/BA/
GCN Circular #12218
Johan Bregeon, Julie McEnery and Masanori Ohno report on behalf of the Fermi Large Area Telescope (LAT) collaboration.
Based on an on-ground analysis, the Large Area Telescope (LAT), on-board the Fermi Gamma-ray Space Telescope, detected high energy emission above 100 MeV, with greater than 10 sigma significance, from the Swift detected burst GRB 110731A (Oates et al, GCN 12215).
The preliminary LAT location of the ground automated analysis is (Ra,Dec) = (280.39,-28.53)+/-0.20 d (68% cont.) which is consistent with the Swift localization and within 0.1d from the optical counterpart position.
Further analysis is ongoing.
The Fermi LAT point of contact for this burst is Johan Bregeon (johan.bregeon@pi.infn.it).
The Fermi LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.
GCN Circular #12219
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team.
Using 1566 s of XRT Photon Counting mode data and 4 UVOT images for GRB 110731A, 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 = 280.50417, -28.53748 which is equivalent to:
```
RA (J2000): 18h 42m 1.00s
Dec (J2000): -28d 32' 14.9"
```
with an uncertainty of 1.4 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 #12220
D. Malesani, G. Leloudas (DARK/NBI), Dong Xu (WIS), A. de Ugarte Postigo, J. Hjorth (DARK/NBI), P. Jakobsson (U. Iceland), and M. B. Nielsen (NOT), report on behalf of a larger collaboration.
We used the Nordic Optical Telescope (La Palma, Spain) equipped with ALFOSC to observe the field of GRB 110731A (Oates et al., GCN 12215). Observations started at 21:22 UT, i.e. 10.22 hr after the trigger. We obtained 3x300 s in R under bad (1.7") seeing conditions.
The afterglow has faded considerably with respect to the report by Bersier (GCN 12216). Photometry is made difficult by the crowding of the field, and we estimate a tentative magnitude for the transient R = 22.2 +- 0.3 mag.
GCN Circular #12221
David Gruber (MPE) reports on behalf of the Fermi GBM Team:
"At 11:09:29.94 UT on 31 July 2011, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 110731A (trigger 333803371 / 110731465) which which was also detected by Fermi LAT (Bregeon et al. 2011, GCN 12218) and Swift (Oates et al. 2011, GCN 12215).
The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 6 degrees. Moreover, this burst was bright enough to result in a Fermi spacecraft autonomous rapid repoint (ARR) maneuver.
The GBM light curve consists of one pulse with a duration (T90) of about 7.3 +/- 0.3 s (50-300 keV). The time-averaged spectrum from T0 s to T0+7.3 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.82 +/- 0.03 and the cutoff energy, parameterized as Epeak, is 317 +/- 10 keV.
The event fluence (10-1000 keV) in this time interval is (2.218 +/- 0.006)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+0.128 s in the 10-1000 keV band is 20.9 +/- 0.5 ph/s/cm^2.
A Band function fits the spectrum equally well with Epeak= 304 +/- 13 keV, alpha = -0.80 +/- 0.03 and beta = -2.98 +/- 0.30.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN Circular #12222
S. R. Oates (MSSL-UCL) reports on behalf of the Swift-UVOT team
The Swift/UVOT began settled observations of the field of GRB 110731A 75s after the trigger (Oates et al., GCN Circ. 12215). We detect a fading source in the white, v, b and u filters at a refined position of RA(J2000), DEC(J2000)= 280.50413 deg, -28.537167 deg. This is equivalent to:
```
    RA (J2000)  18:42:00.99
   Dec (J2000) -28:32:13.8
```
with an estimated uncertainty of 0.5 arcsec (radius, 90% confidence). This is consistent with the UVOT position reported in Oates et al. (GCN Circ. 12215) and with the enhanced position of the X-ray afterglow (Beardmore et al., GCN Circ. 12219). The non-detection in the uv filters is consistent with a redshift of between 2 and 3.
Preliminary magnitudes using the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627) for the finding chart (FC) and summed exposures at the location of the optical afterglow are:
```
Filter  T_start(s)  T_stop(s)   Exp(s)       Mag
#####################################################
wh (FC)     75         225       147    15.85+/-0.02
wh          567        587       19     17.64+/-0.11
v           790        810       19     16.90+/-0.23
b           542        562       19     17.87+/-0.23 
u (FC) 	    287        537       246    17.71+/-0.08
u           1118       1138      19     18.37+/-0.44
uvw1        666        1286      78     >18.88   
uvm2        642        1261      78     >18.77   
uvw2        592        1385      97     >19.24   
#####################################################
```
We note that photometry is difficult due to the field being crowded and the presence of a faint contaminating source in the source region. The values quoted above are not corrected for the non-negliable Galactic extinction due to the reddening of E(B-V) = 0.18 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #12223
S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf of the Konus-Wind team, report:
The long GRB 110731A (Swift-BAT trigger #458448: Oates, et al., GCN 12215; Krimm et al., GCN 12217; also detected by Fermi-LAT: McEnery, GCN 12218, and Fermi-GBM: Gruber, GCN 12221) triggered Konus-Wind at T0=40174.604 s UT (11:09:34.604).
The burst light curve shows a multipeaked structure with a duration of ~7 s. There is a low-level emission seen in the G2 band (~80-360 keV) up to ~T0+40 s.
As observed by Konus-Wind the burst had a fluence of 1.63(-0.10,+0.11)x10^-5 erg/cm2, and a 64-ms peak flux measured from T0+4.304 s of (6.0 +/- 1.3)x10^-6 erg/cm2/s (both in the 20 keV - 6 MeV energy range).
The time-integrated spectrum of the burst (from T0 to T0+8.448 s) can be fitted (in the 20 keV - 6 MeV range) by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep), with alpha = -0.74(-0.15, +0.16), and Ep = 288(-25, +30) keV (chi2 = 98.2/76 dof). Fitting by GRB (Band) model yields the same alpha and Ep, and only an upper limit on the high energy photon index: beta < -2.92 (chi2 = 98.1/75 dof).
All the quoted errors are at the 90% confidence level.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB110731_T40174/
GCN Circular #12224
O. M. Littlejohns, P. A. Evans, A. P. Beardmore (U. Leicester) and S. R. Oates (UCL-MSSL) report on behalf of the Swift-XRT team:
We have analysed 8.1 ks of XRT data for GRB 110731A (Oates et al. GCN Circ. 12215), from 56 s to 36.0 ks after the BAT trigger. The data comprise 607 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 enhanced XRT position for this burst was given by Beardmore et al. (GCN. Circ 12219).
The light curve can be modelled with a series of power-law decays. The initial decay index is alpha=1.04 (+0.05, -0.10). At T+502 s the decay steepens to an alpha of 1.183 (+0.027, -0.024) before breaking again at T+29.0 ks to a final decay with index alpha=4.2 (+5.8, -2.0). We note that the uncertainty in this final decay is large due to the small number of data points after the final break.
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.08 (+/-0.05). The best-fitting absorption column is 2.05 (+0.14, -0.13) x 10^21 cm^-2, in excess of the Galactic value of 1.0 x 10^21 cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a photon index of 1.92 (+/-0.12) and a best-fitting absorption column of 1.7 (+0.4, -0.3) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.0 x 10^-11 (5.5 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     1.7 (+0.4, -0.3) x 10^21 cm^-2
Galactic foreground: 1.0 x 10^21 cm^-2
Excess significance: 8.4 sigma
Photon index:	     1.92 (+/-0.12)
```
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00458448.
This circular is an official product of the Swift-XRT team.
GCN Circular #12225
N. R. Tanvir, K. Wiersema (U. Leicester), A. J. Levan (U. Warwick), S. B. Cenko (U. Berkeley) and T. Geballe (Gemini) report on behalf of a larger collaboration:
We observed the location of GRB 110731A (Oates et al. GCN12215) with the GMOS-N instrument on Gemini-North (Mauna Kea), beginning at 1 Aug 2011 09:07 UT. Spectroscopic observations totalling 3600s were obtained in good conditions using the B600 grating (spanning approximately 3800 A to 6650 A). We identify a broad Ly-alpha absorption feature and several absorption lines of O, C, Si and Al at a common redshift of z=3D2.83.=C2=A0 This includes fine structure lines of O, C and Si, as seen in other GRB sight-lines, confirming that this is the redshift of the burst.
Provisional calibration of the acquisition image gives a magnitude of R= 22.0 for the afterglow (uncorrected for foreground extinction of A_R ~ 0.5), suggesting a fairly shallow rate of decay since the NOT epoch (Malesani et al. GCN12220).
GCN Circular #12226
D. Kuroda (OAO, NAOJ), H. Hanayama, T. Miyaji, J. Watanabe (IAO, NAOJ), K. Yanagisawa (OAO, NAOJ), S.Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto) and N. Kawai(Tokyo Tech) report on behalf of the MITSuME collaboration:
We observed the field of GRB 110731A (Oates et al., GCNC 12215) with the optical three color (g', Rc and Ic) CCD camera attached to the Murikabushi 1m telescope of Ishigakijima Astronomical Observatory.
The observation started on 13:02:23 UT (~1.9 h after the burst). We did not find any new point source within the enhanced XRT error circle (Beardmore et al., GCNC 12219) in all the three bands. We could not detect the previously reported afterglow (Bersier, GCNC 12216; Malesani et al., GCNC 12220).
Three sigma upper limits of the OT are listed below. We used GSC2.3 catalog for flux calibration.
```
#T0+[day]  MID-UT    T-EXP[sec]   g'    Rc    Ic
----------------------------------------------------
0.12025    14:02:40    6180.0   >21.8 >20.6 >20.1
----------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]
```
GCN Circular #12227
A. Zauderer, E. Berger (Harvard), and D.A. Frail (NRAO) report on behalf of a larger collaboration:
"We observed the Swift burst GRB 110731A (GCN 12215) with the EVLA beginning on 2011 Aug 1.15 UT (0.68 days after the burst). Observations were performed at 5.75 and 22 GHz for about 30 min at each frequency. No radio source is detected in coincidence with the optical afterglow (GCN 12215), to a 3-sigma limit of ~50 microJy at 5.75 GHz. Additional observations are planned."
GCN Circular #12242
P. J. Tristram (MJUO), A. Fukui (Nagoya U.), K. Ohnishi (Nagano NCT) and T. Sako (Nagoya U.) report on behalf of the MOA collaboration.
We began prompt observations of the afterglow of GRB110731A (Oates et al., GCN 12215) at July 31 11:12:47 UT responding to the Swift trigger 458448 (3.3 min after the trigger) using the 61 cm B&C telescope at the Mt John University Observatory in New Zealand. We obtained a series of I and V band images with 60 sec exposure times followed by some 120 sec exposures until 12:56 UT (105 min after the trigger). The total number of I and V images are 39 and 35, respectively. Although the first image had a poor psf, the following images had well-shaped psf's and we confirmed the steeply fading afterglow, which is consistent with the previous reports (e.g. Bersier et al. GCN 12216), on these images in both the I and V bands. The afterglow is located within the error circle reported by Oates et al. GCN 12222. The magnitude of the afterglow on the second and on the last images in the I band obtained by psf-fitting photometry with the DoPHOT package (Schechter et al. 1993) and calibrated to the USNO-B1.0 N magnitude (similar to I magnitude) follow.
```
------------------------------------------------------
Filter mid_JD-2450000 exptime[sec] dT[min] Nmag error 
I      5773.96831       60          4.86   14.75  0.20
I      5774.03807      120        105.31   20.2   2.7
------------------------------------------------------
```
Here dT denotes the difference between the mid_JD (mid time of exposure) and the trigger time. The large error in the magnitude of the last image resulted from the calibration relying on extrapolation.
GCN Circular #12244
Y. Hanabata, T. Uehara, T. Takahashi, M. Mizuno, M. Ohno, Y. Fukazawa (Hiroshima U.), T. Yasuda, Y. Terada, M. Tashiro, W. Iwakiri, K. Takahara (Saitama U.), S. Sugita (Nagoya U.), K. Yamaoka (Aoyama Gakuin U.), M. Kokubun, T. Takahashi (ISAS/JAXA), Y. E. Nakagawa (Waseda U.), N. Ohmori, M. Akiyama, M. Yamauchi (Univ. of Miyazaki), Y. Urata, P. Tsai, C-J. Chuang (NCU), K. Nakazawa, K. Makishima (Univ. of Tokyo), on behalf of the Suzaku WAM team, report:
The bright long GRB110731A (Swift/BAT trigger #458448: Oates et al. GCN 12215, also detected by Fermi-LAT: Bregeon et al. GCN 12218) triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV at 11:09:30.211 UT (=T0).
The observed light curve shows multiple peaks starting at T0-1.5 s, ending at T0+7.5 s, with a duration (T90) of about 6.56 seconds. The fluence in 100 - 1000 keV was 1.31 (-0.12, +0.08) x 10^-5 erg/cm^2. The 1-s peak flux measured from T0+3.5 s was 5.20 (-0.70, +0.57) photons/cm^2/s in the same range.
Preliminary result shows that the time-averaged spectrum from T0-1.5 s to T0+7.5 s is well fitted by a power-law with exponential cutoff model:
```
 dN/dE ~  E^{-alpha} * exp(-(2-alpha)*E/Epeak) with
 alpha       0.93 (-0.66, +0.57), and
 Epeak       339 (-51, +40) keV (chi^2/d.o.f. = 11.2/12).
```
The light curves for this burst will be available at: http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html
GCN Circular #12333
A. S. Moskvitin, V. V. Sokolov, O. I. Spiridonova (SAO RAS, Russia), M. V. Andreev, A. V. Sergeev, N. A. Parakhin (Terskol Branch of Institute of Astronomy, Russia)
We observed the field of GRB 110731A (Oates et al., GCN 12215) on July, 31 with 0.6-m Zeiss-600 (Terskol Branch of Institute of Astronomy, Russia) equipped with the PixelVision Vienna CCD (1024 x 1024, bin 2 x 2) + R filter, and 1-m Zeiss-1000 (SAO RAS, Russia) equipped with the E2V 42-40 CCD (2048 x 2048, bin 2 x 2) + B and Rc filters. In both cases the observations carried out at a high airmass and with the seeing ~4".
At all stacked images we did not detect any source within the Swift/UVOT error circle (Oates., GCN 12222). Close to the error circle are visible two objects which are also present in the USNO-B.1 catalogue: S1: USNO-B.1 0614-0802286 (R.A.=18:42:00.72, Dec.=-28:32:14.9, E.=2000.0) & S2: USNO-B.1 0614-0802328 (R.A.=18:42:01.24, Dec.=-28:32:11.6, E.=2000.0). Our astrometric calibration and photometry of S1 object showed that it can contain flux from OT but due to large seeing we can not distinguish bright S1 and faint OT.
All three co-added images are shown at ftp://ftp.sao.ru/pub/grb/GRB110731A/GRB110731A.jpg Upper limits are shown at the following table.
```
_________________________________________________________
mid. time, UT   filter exp., sec  3-sigma lim. telescope
_________________________________________________________
19:15           R      53 x 200   19.9        Zeiss-600
19:24           Rc     31 x 60    21.7        Zeiss-1000
19:38           B      22 x 60    20.8        Zeiss-1000
_________________________________________________________
```
We use USNO-B.1 star 0614-0802353 (R.A.=18:42:01.83, Dec.-28:32:23.9, E.=2000.0, B2 = 15.77, R2 = 14.29) as a standard, and did not apply Galaxy extinction correction.
This message can be cited.
GCN Report 343.1
GCN_Report 343.1 has been posted: http://gcn.gsfc.nasa.gov/reports/report_343_1.pdf by S.R. Oates at MSSL-UCL titled: "Final Swift Observations of GRB 110731A"
1212.0973 from 6 Dec 12
The Fermi-LAT Collaboration et al.: Multiwavelength observations of GRB 110731A: GeV emission from onset to afterglow
We report on the multiwavelength observations of the bright, long gamma-ray burst \GRB, by the \Fermi and \Swift observatories, and by the MOA and GROND optical telescopes. The analysis of the prompt phase reveals that \GRB shares many features with bright Large Area Telescope bursts observed by \Fermi during the first 3 years on-orbit: a light curve with short time variability across the whole energy range during the prompt phase, delayed onset of the emission above 100 MeV, extra power law component and temporally extended high-energy emission. In addition, this the first GRB for which simultaneous GeV, X-ray, and optical data are available over multiple epochs beginning just after the trigger time and extending for more than 800 s, allowing temporal and spectral analysis in different epochs that favor emission from the forward shock in a wind-type medium. The observed temporally extended GeV emission is most likely part of the high-energy end of the afterglow emission. Both the single-zone pair transparency constraint for the prompt signal, and the spectral and temporal analysis of the forward shock afterglow emission, independently lead to an estimate of the bulk Lorentz factor of the jet $\Gamma\sim$ 500 - 550.
1305.3689 from 17 May 13
Martin Lemoine et al.: On the magnetisation of gamma-ray burst blast waves
The origin of magnetic fields that permeate the blast waves of gamma-ray bursts is a long-standing problem. The present paper argues that in four GRBs revealing extended emission at >100 MeV, with follow-up in the radio, optical and X-ray domains at later times, this magnetisation can be described as the partial decay of the microturbulence that is generated in the shock precursor. Assuming that the extended high energy emission can be interpreted as synchrotron emission of shock accelerated electrons, we model the multi-wavelength light curves of GRB 090902B, GRB 090323, GRB 090328 and GRB 110731A, using a simplified then a full synchrotron calculation with power law decaying microturbulence \epsilon_B \propto t^{\alpha_t} (t denotes the time since injection through the shock, in the comoving blast frame). We find that these models point to a consistent value of the decay exponent -0.5 < \alpha_t < -0.4.
1503.07449 from 26 Mar 15
Nissim Fraija: GRB 110731A: Early afterglow in stellar wind powered by a magnetized outflow
One of the most energetic gamma-ray burst GRB 110731A was observed from optical to GeV energy range. Previous analysis on the prompt phase revealed similarities with the Large Area Telescope (LAT) bursts observed by Fermi: i) a delayed onset of the high-energy emission ($> 100$ MeV), ii) a short-lasting bright peak at later times and iii) a temporally extended component from this phase and lasting hundreds of seconds. Additionally to the prompt phase, multiwavelength observations over different epochs showed that the spectral energy distribution was better fitted by a wind afterglow model. We present a leptonic model based on an early afterglow that evolves in a stellar wind of its progenitor. We apply this model to interpret the temporally extended LAT emission and the brightest LAT peak exhibited by the prompt phase of GRB 110731A. Additionally, using the same set of parameters, we describe the multiwavelength afterglow observations. The origin of the temporally extended LAT, X-ray and optical flux is explained through synchrotron radiation from the forward shock and the brightest LAT peak is described evoking the synchrotron self-Compton emission from the reverse shock. The bulk Lorentz factor required in this model ($\Gamma\simeq520$) lies in the range of values demanded for most LAT-detected gamma-ray bursts. We show that the strength of the magnetic field in the reverse-shock region is $\sim$ 50 times stronger than in the forward-shock region. This result suggests that for GRB 110731A, the central engine is likely entrained with strong magnetic fields.
1508.02130 from 11 Aug 15
Nissim Fraija et al.: The early afterglow and magnetized ejecta present in GRB 110731A
One of the most energetic gamma-ray bursts GRB 110731A, was observed from optical to GeV energy range by Fermi and Swift Observatories, and by the MOA and GROND optical telescopes. The multiwavelength observations over different epochs (from trigger time to more than 800 s) showed that the spectral energy distribution was better fitted by a wind afterglow model. We present a leptonic model based on an early afterglow that evolves in a stellar wind to describe the multiwavelength light curves observations. In particular, the origin of the LAT emission is explained through the superposition of synchrotron radiation from the forward shock and synchrotron self-Compton emission from the reverse shock. The bulk Lorentz factor required in this model is $\Gamma\simeq520$ and the result suggests that the ejecta must be magnetized.

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