Gamma-ray Burst 150911A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 11 Sep 15 18:40:37 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     655262,   Seg_Num: 0
GRB_RA:           67.424d {+04h 29m 42s} (J2000),
                  67.633d {+04h 30m 32s} (current),
                  66.758d {+04h 27m 02s} (1950)
GRB_DEC:          +5.743d {+05d 44' 34"} (J2000),
                  +5.776d {+05d 46' 34"} (current),
                  +5.634d {+05d 38' 04"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       1987 [cnts]    Image_Peak=123 [image_cnts]
TRIGGER_DUR:     0.512 [sec] 
TRIGGER_INDEX:   41     E_range: 25-100 keV
BKG_INTEN:       21597 [cnts]
BKG_TIME:        67208.87 SOD {18:40:08.87} UT
BKG_DUR:         8 [sec]
GRB_DATE:        17276 TJD;   254 DOY;   15/09/11
GRB_TIME:        67221.48 SOD {18:40:21.48} UT
GRB_PHI:         -46.48 [deg]
GRB_THETA:        29.25 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     15.23 [sigma]
IMAGE_SIGNIF:    7.46 [sigma]
MERIT_PARAMS:     +1  +0  +0  -1  +2  -2  +0  +0 +20  +0 
SUN_POSTN:       169.62d {+11h 18m 29s}   +4.46d {+04d 27' 53"}
SUN_DIST:        101.43 [deg]   Sun_angle= 6.8 [hr] (West of Sun)
MOON_POSTN:      153.43d {+10h 13m 42s}   +8.28d {+08d 16' 44"}
MOON_DIST:        85.02 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      189.46,-27.89 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       66.60,-15.88 [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 = 135.08,20.49 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 11 Sep 15 18:41:48 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     655262,   Seg_Num: 0
POINT_RA:         67.404d {+04h 29m 37s} (J2000)
POINT_DEC:        +5.745d {+05d 44' 43"} (J2000)
IMG_START_DATE:  17276 TJD;   254 DOY;   15/09/11
IMG_START_TIME:  67301.39 SOD {18:41:41.39} UT,   79.9 [sec] since BAT Trigger Time
COUNTS:          15    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:     Fri 11 Sep 15 18:44:22 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     655262,   Seg_Num: 0
GRB_RA:           67.424d {+04h 29m 42s} (J2000),
                  67.633d {+04h 30m 32s} (current),
                  66.758d {+04h 27m 02s} (1950)
GRB_DEC:          +5.743d {+05d 44' 34"} (J2000),
                  +5.776d {+05d 46' 34"} (current),
                  +5.634d {+05d 38' 04"} (1950)
GRB_DATE:        17276 TJD;   254 DOY;   15/09/11
GRB_TIME:        67221.48 SOD {18:40:21.48} UT
TRIGGER_INDEX:   41
GRB_PHI:         -46.48 [deg]
GRB_THETA:        29.25 [deg]
DELTA_TIME:      19.00 [sec]
TRIGGER_DUR:     0.512 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     15.23 [sigma]
IMAGE_SIGNIF:    7.46 [sigma]
LC_URL:          sw00655262000msb.lc
SUN_POSTN:       169.62d {+11h 18m 30s}   +4.46d {+04d 27' 50"}
SUN_DIST:        101.43 [deg]   Sun_angle= 6.8 [hr] (West of Sun)
MOON_POSTN:      153.46d {+10h 13m 49s}   +8.27d {+08d 16' 12"}
MOON_DIST:        85.05 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      189.46,-27.89 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       66.60,-15.88 [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 = 135.08,20.49 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 11 Sep 15 18:45:17 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     655262,   Seg_Num: 0
POINT_RA:         67.405d {+04h 29m 37s} (J2000)
POINT_DEC:        +5.745d {+05d 44' 42"} (J2000)
POINT_ROLL:      84.216d
IMG_START_DATE:  17276 TJD;   254 DOY;   15/09/11
IMG_START_TIME:  67303.66 SOD {18:41:43.66} UT,   82.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.054
N_STARS:         72
X_OFFSET:        628 [pixels]
Y_OFFSET:        517 [pixels]
X_MAX:           1587 [pixels]
Y_MAX:           1476 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    8
SL_URL:          sw00655262000msufc0082.fits
SUN_POSTN:       169.62d {+11h 18m 30s}   +4.46d {+04d 27' 49"}
SUN_DIST:        101.45 [deg]   Sun_angle= 6.8 [hr] (West of Sun)
MOON_POSTN:      153.46d {+10h 13m 51s}   +8.27d {+08d 16' 05"}
MOON_DIST:        85.08 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      189.44,-27.90 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       66.58,-15.88 [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:     Fri 11 Sep 15 18:44:49 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     655262,   Seg_Num: 0
POINT_RA:         67.405d {+04h 29m 37s} (J2000)
POINT_DEC:        +5.745d {+05d 44' 42"} (J2000)
POINT_ROLL:      84.216d
IMG_START_DATE:  17276 TJD;   254 DOY;   15/09/11
IMG_START_TIME:  67303.66 SOD {18:41:43.66} UT,   82.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.054
N_STARS:         72
X_OFFSET:        628 [pixels]
Y_OFFSET:        517 [pixels]
X_MAX:           1587 [pixels]
Y_MAX:           1476 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    8
SL_URL:          sw00655262000msufc0082.fits
SUN_POSTN:       169.62d {+11h 18m 30s}   +4.46d {+04d 27' 49"}
SUN_DIST:        101.45 [deg]   Sun_angle= 6.8 [hr] (West of Sun)
MOON_POSTN:      153.46d {+10h 13m 50s}   +8.27d {+08d 16' 09"}
MOON_DIST:        85.08 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      189.44,-27.90 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       66.58,-15.88 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 11 Sep 15 18:46:17 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     655262,   Seg_Num: 0
POINT_RA:         67.405d {+04h 29m 37s} (J2000)
POINT_DEC:        +5.745d {+05d 44' 42"} (J2000)
ROLL:            84.216d
IMG_START_DATE:  17276 TJD;   254 DOY;   15/09/11
IMG_START_TIME:  67303.66 SOD {18:41:43.66} UT,   82.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     463689718
X_OFFSET:        947 [pixels]
Y_OFFSET:        836 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1107
Y_GRB_POS:       996
BINNING_INDEX:   1
IM_URL:          sw00655262000msuni0098.fits
SUN_POSTN:       169.63d {+11h 18m 30s}   +4.46d {+04d 27' 48"}
SUN_DIST:        101.45 [deg]   Sun_angle= 6.8 [hr] (West of Sun)
MOON_POSTN:      153.47d {+10h 13m 53s}   +8.27d {+08d 15' 56"}
MOON_DIST:        85.09 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      189.44,-27.90 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       66.58,-15.88 [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:     Fri 11 Sep 15 18:46:41 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     655262,   Seg_Num: 0
POINT_RA:         67.405d {+04h 29m 37s} (J2000)
POINT_DEC:        +5.745d {+05d 44' 42"} (J2000)
ROLL:            84.216d
IMG_START_DATE:  17276 TJD;   254 DOY;   15/09/11
IMG_START_TIME:  67303.66 SOD {18:41:43.66} UT,   82.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     463689718
X_OFFSET:        947 [pixels]
Y_OFFSET:        836 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1107
Y_GRB_POS:       996
BINNING_INDEX:   1
IM_URL:          sw00655262000msuni0098.fits
SUN_POSTN:       169.63d {+11h 18m 30s}   +4.46d {+04d 27' 47"}
SUN_DIST:        101.45 [deg]   Sun_angle= 6.8 [hr] (West of Sun)
MOON_POSTN:      153.47d {+10h 13m 54s}   +8.26d {+08d 15' 53"}
MOON_DIST:        85.09 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      189.44,-27.90 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       66.58,-15.88 [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:     Fri 11 Sep 15 18:47:38 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     655262,   Seg_Num: 0
GRB_RA:           67.4324d {+04h 29m 43.77s} (J2000),
                  67.6416d {+04h 30m 33.98s} (current),
                  66.7664d {+04h 27m 03.92s} (1950)
GRB_DEC:          +5.7344d {+05d 44' 03.8"} (J2000),
                  +5.7678d {+05d 46' 04.0"} (current),
                  +5.6261d {+05d 37' 33.8"} (1950)
GRB_ERROR:       3.9 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  17276 TJD;   254 DOY;   15/09/11
IMG_START_TIME:  67421.00 SOD {18:43:41.00} UT,   199.5 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       169.63d {+11h 18m 30s}   +4.46d {+04d 27' 46"}
SUN_DIST:        101.43 [deg]   Sun_angle= 6.8 [hr] (West of Sun)
MOON_POSTN:      153.48d {+10h 13m 56s}   +8.26d {+08d 15' 45"}
MOON_DIST:        85.07 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      189.47,-27.89 [deg] galactic lon,lat of the burst
ECL_COORDS:       66.61,-15.89 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.11% < P(seren) < 0.58%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 11 Sep 15 18:51:53 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     655262,   Seg_Num: 0
POINT_RA:         67.403d {+04h 29m 37s} (J2000)
POINT_DEC:        +5.746d {+05d 44' 46"} (J2000)
POINT_ROLL:      84.213d
IMG_START_DATE:  17276 TJD;   254 DOY;   15/09/11
IMG_START_TIME:  67515.66 SOD {18:45:15.66} UT,   294.2 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.888
N_STARS:         64
X_OFFSET:        388 [pixels]
Y_OFFSET:        277 [pixels]
X_MAX:           1827 [pixels]
Y_MAX:           1716 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    4
SL_URL:          sw00655262000msufc0294.fits
SUN_POSTN:       169.63d {+11h 18m 31s}   +4.46d {+04d 27' 42"}
SUN_DIST:        101.46 [deg]   Sun_angle= 6.8 [hr] (West of Sun)
MOON_POSTN:      153.52d {+10h 14m 04s}   +8.25d {+08d 15' 10"}
MOON_DIST:        85.14 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      189.44,-27.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       66.58,-15.87 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 11 Sep 15 18:52:11 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     655262,   Seg_Num: 0
POINT_RA:         67.403d {+04h 29m 37s} (J2000)
POINT_DEC:        +5.746d {+05d 44' 46"} (J2000)
POINT_ROLL:      84.213d
IMG_START_DATE:  17276 TJD;   254 DOY;   15/09/11
IMG_START_TIME:  67515.66 SOD {18:45:15.66} UT,   294.2 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.888
N_STARS:         64
X_OFFSET:        388 [pixels]
Y_OFFSET:        277 [pixels]
X_MAX:           1827 [pixels]
Y_MAX:           1716 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    4
SL_URL:          sw00655262000msufc0294.fits
SUN_POSTN:       169.63d {+11h 18m 31s}   +4.46d {+04d 27' 42"}
SUN_DIST:        101.46 [deg]   Sun_angle= 6.8 [hr] (West of Sun)
MOON_POSTN:      153.52d {+10h 14m 05s}   +8.25d {+08d 15' 07"}
MOON_DIST:        85.14 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      189.44,-27.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       66.58,-15.87 [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:     Fri 11 Sep 15 18:52:18 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     655262,   Seg_Num: 0
GRB_RA:           67.4331d {+04h 29m 43.94s} (J2000),
                  67.6423d {+04h 30m 34.15s} (current),
                  66.7671d {+04h 27m 04.09s} (1950)
GRB_DEC:          +5.7354d {+05d 44' 07.4"} (J2000),
                  +5.7688d {+05d 46' 07.6"} (current),
                  +5.6271d {+05d 37' 37.4"} (1950)
GRB_ERROR:       2.5 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  17276 TJD;   254 DOY;   15/09/11
IMG_START_TIME:  67421.00 SOD {18:43:41.00} UT,   199.5 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       169.63d {+11h 18m 31s}   +4.46d {+04d 27' 42"}
SUN_DIST:        101.43 [deg]   Sun_angle= 6.8 [hr] (West of Sun)
MOON_POSTN:      153.52d {+10h 14m 05s}   +8.25d {+08d 15' 06"}
MOON_DIST:        85.11 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      189.47,-27.89 [deg] galactic lon,lat of the burst
ECL_COORDS:       66.61,-15.89 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        This is an Update Notice -- the RA,Dec values herein supersede the previous XRT_POS Notice.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        This position was enhanced using UVOT field astrometry.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.11% < P(seren) < 0.58%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 11 Sep 15 18:53:14 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     655262,   Seg_Num: 0
POINT_RA:         67.403d {+04h 29m 37s} (J2000)
POINT_DEC:        +5.746d {+05d 44' 46"} (J2000)
ROLL:            84.213d
IMG_START_DATE:  17276 TJD;   254 DOY;   15/09/11
IMG_START_TIME:  67515.66 SOD {18:45:15.66} UT,   294.2 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     463689930
X_OFFSET:        947 [pixels]
Y_OFFSET:        836 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1107
Y_GRB_POS:       996
BINNING_INDEX:   1
IM_URL:          sw00655262000msuni0310.fits
SUN_POSTN:       169.63d {+11h 18m 31s}   +4.46d {+04d 27' 41"}
SUN_DIST:        101.46 [deg]   Sun_angle= 6.8 [hr] (West of Sun)
MOON_POSTN:      153.53d {+10h 14m 07s}   +8.25d {+08d 14' 58"}
MOON_DIST:        85.15 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      189.44,-27.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       66.58,-15.87 [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:     Fri 11 Sep 15 18:53:33 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     655262,   Seg_Num: 0
POINT_RA:         67.403d {+04h 29m 37s} (J2000)
POINT_DEC:        +5.746d {+05d 44' 46"} (J2000)
ROLL:            84.213d
IMG_START_DATE:  17276 TJD;   254 DOY;   15/09/11
IMG_START_TIME:  67515.66 SOD {18:45:15.66} UT,   294.2 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     463689930
X_OFFSET:        947 [pixels]
Y_OFFSET:        836 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1107
Y_GRB_POS:       996
BINNING_INDEX:   1
IM_URL:          sw00655262000msuni0310.fits
SUN_POSTN:       169.63d {+11h 18m 31s}   +4.46d {+04d 27' 41"}
SUN_DIST:        101.46 [deg]   Sun_angle= 6.8 [hr] (West of Sun)
MOON_POSTN:      153.53d {+10h 14m 07s}   +8.25d {+08d 14' 56"}
MOON_DIST:        85.15 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      189.44,-27.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       66.58,-15.87 [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 #18280
R. L. C. Starling (U Leicester), S. D. Barthelmy (GSFC), D. N. Burrows (PSU), V. D'Elia (ASDC), H. A. Krimm (CRESST/GSFC/USRA), F. E. Marshall (NASA/GSFC), B. Sbarufatti (INAF-OAB/PSU) and M. H. Siegel (PSU) report on behalf of the Swift Team:
At 18:40:21 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 150911A (trigger=655262). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 67.424, +5.743, which is
```
   RA(J2000)  =  04h 29m 42s
   Dec(J2000) = +05d 44' 34"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a pair of overlapping peaks with a total duration of about 12 sec. The peak count rate was ~5000 counts/sec (15-350 keV), at ~4 sec after the trigger.
The XRT began observing the field at 18:41:41.3 UT, 79.9 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source with an enhanced position: RA, Dec 67.4331, 5.7350 which is equivalent to:
```
   RA(J2000)  = 04h 29m 43.95s
   Dec(J2000) = +05d 44' 05.9"
```
with an uncertainty of 2.3 arcseconds (radius, 90% containment). This location is 43 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 1.87 x 10^21 cm^-2 (Willingale et al. 2013).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 82 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 0.32.
Burst Advocate for this burst is R. L. C. Starling (rlcs1 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 NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 11 Sep 15 18:58:31 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     655262,   Seg_Num: 0
POINT_RA:         67.403d {+04h 29m 37s} (J2000)
POINT_DEC:        +5.746d {+05d 44' 46"} (J2000)
POINT_ROLL:      84.213d
IMG_START_DATE:  17276 TJD;   254 DOY;   15/09/11
IMG_START_TIME:  68093.16 SOD {18:54:53.16} UT,   871.7 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.595
N_STARS:         100
X_OFFSET:        388 [pixels]
Y_OFFSET:        277 [pixels]
X_MAX:           1827 [pixels]
Y_MAX:           1716 [pixels]
DET_THRESH:      16
PHOTO_THRESH:    9
SL_URL:          sw00655262000msufc0871.fits
SUN_POSTN:       169.63d {+11h 18m 32s}   +4.46d {+04d 27' 36"}
SUN_DIST:        101.46 [deg]   Sun_angle= 6.8 [hr] (West of Sun)
MOON_POSTN:      153.57d {+10h 14m 17s}   +8.24d {+08d 14' 14"}
MOON_DIST:        85.19 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      189.44,-27.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       66.58,-15.87 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 11 Sep 15 18:58:51 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     655262,   Seg_Num: 0
POINT_RA:         67.403d {+04h 29m 37s} (J2000)
POINT_DEC:        +5.746d {+05d 44' 46"} (J2000)
POINT_ROLL:      84.213d
IMG_START_DATE:  17276 TJD;   254 DOY;   15/09/11
IMG_START_TIME:  68093.16 SOD {18:54:53.16} UT,   871.7 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.595
N_STARS:         100
X_OFFSET:        388 [pixels]
Y_OFFSET:        277 [pixels]
X_MAX:           1827 [pixels]
Y_MAX:           1716 [pixels]
DET_THRESH:      16
PHOTO_THRESH:    9
SL_URL:          sw00655262000msufc0871.fits
SUN_POSTN:       169.63d {+11h 18m 32s}   +4.46d {+04d 27' 36"}
SUN_DIST:        101.46 [deg]   Sun_angle= 6.8 [hr] (West of Sun)
MOON_POSTN:      153.57d {+10h 14m 17s}   +8.24d {+08d 14' 12"}
MOON_DIST:        85.19 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      189.44,-27.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       66.58,-15.87 [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:     Fri 11 Sep 15 19:00:20 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     655262,   Seg_Num: 0
POINT_RA:         67.403d {+04h 29m 37s} (J2000)
POINT_DEC:        +5.746d {+05d 44' 46"} (J2000)
ROLL:            84.213d
IMG_START_DATE:  17276 TJD;   254 DOY;   15/09/11
IMG_START_TIME:  68093.16 SOD {18:54:53.16} UT,   871.7 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     463690508
X_OFFSET:        947 [pixels]
Y_OFFSET:        836 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1107
Y_GRB_POS:       996
BINNING_INDEX:   1
IM_URL:          sw00655262000msuni0887.fits
SUN_POSTN:       169.63d {+11h 18m 32s}   +4.46d {+04d 27' 34"}
SUN_DIST:        101.47 [deg]   Sun_angle= 6.8 [hr] (West of Sun)
MOON_POSTN:      153.58d {+10h 14m 20s}   +8.23d {+08d 13' 59"}
MOON_DIST:        85.21 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      189.44,-27.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       66.58,-15.87 [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:     Fri 11 Sep 15 19:00:43 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     655262,   Seg_Num: 0
POINT_RA:         67.403d {+04h 29m 37s} (J2000)
POINT_DEC:        +5.746d {+05d 44' 46"} (J2000)
ROLL:            84.213d
IMG_START_DATE:  17276 TJD;   254 DOY;   15/09/11
IMG_START_TIME:  68093.16 SOD {18:54:53.16} UT,   871.7 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     463690508
X_OFFSET:        947 [pixels]
Y_OFFSET:        836 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1107
Y_GRB_POS:       996
BINNING_INDEX:   1
IM_URL:          sw00655262000msuni0887.fits
SUN_POSTN:       169.63d {+11h 18m 32s}   +4.46d {+04d 27' 34"}
SUN_DIST:        101.47 [deg]   Sun_angle= 6.8 [hr] (West of Sun)
MOON_POSTN:      153.59d {+10h 14m 21s}   +8.23d {+08d 13' 56"}
MOON_DIST:        85.21 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      189.44,-27.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       66.58,-15.87 [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 #18282
Kenshi Yanagisawa, Daisuke Kuroda, Yasuhiro Shimizu, Hideyuki Izumiura (OAO/NAOJ), Michitoshi Yoshida (Hiroshima-U), Kouji Ohta(Kyoto-U) and Nobuyuki Kawai(Tokyo Tech.) report on behalf of the MITSuME collaboration:
We observed the field of GRB150911A (Starling et al, GCN18280) in Ks-band with a wide-field near infrared imager at Okayama Astrophysical Observatory (Japan). The imager has effective aperture of 0.91 m.
Observations started from 18:56 UT on 11th September, just 16 min after the BAT trigger, to 19:10 UT. The total exposure of 6 min was successfully obtained.
In our co-add image, we did not find any new point source within the enhanced XRT error circle (Starling et al, GCN18280) down to limiting magnitude of Ks=14.3 (Vega, S/N=10) . The photometric calibration was made against 2MASS field stars.
```
T0+[s]      MID-UT     T-EXP[sec]      Ks
---------------------------------------------------
 +1380      19:03          375        >14.3
---------------------------------------------------
T0+ : Elapsed time after the burt [sec]
T-EXP: Total Exposure time [sec]
```
GCN Circular #18283
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team.
Using 1481 s of XRT Photon Counting mode data and 2 UVOT images for GRB 150911A, 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 = 67.43406, +5.73533 which is equivalent to:
```
RA (J2000): 04h 29m 44.17s
Dec (J2000): +05d 44' 07.2"
```
with an uncertainty of 1.7 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 #18286
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 150911A (Starling et al., GCNC 18280) 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 2015-09-11 18:41:02 UT (~41 sec after the burst). We did not find any new point source within the enhanced XRT circle (Goad et al., GCNC 18283) in all the three bands.
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
-----------------------------------------------------
0.01168    18:57:10    1380.0   >20.2  >19.5  >19.1
-----------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]
```
GCN Circular #18290
C. Pagani (U. Leicester), A.P. Beardmore (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'ai (INAF-IASFPA), T.G.R. Roegiers (PSU), L.M. McCauley (PSU), J.A. Kennea (PSU), P.A. Evans (U. Leicester) and R.L.C. Starling report on behalf of the Swift-XRT team:
We have analysed 10 ks of XRT data for GRB 150911A (Starling et al. GCN Circ. 18280), from 65 s to 23.7 ks after the BAT trigger. The data comprise 114 s in Windowed Timing (WT) mode (the first 7 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 Goad et al. (GCN Circ. 18283).
The late-time light curve (from T0+4.9 ks) can be modelled with a power-law decay with a decay index of alpha=1.81 (+0.14, -0.13).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.58 (+0.11, -0.10). The best-fitting absorption column is 2.7 (+0.6, -0.5) x 10^21 cm^-2, in excess of the Galactic value of 1.9 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.96 (+0.14, -0.13) and a best-fitting absorption column of 4.1 (+/-0.7) 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 (6.1 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     4.1 (+/-0.7) x 10^21 cm^-2
Galactic foreground: 1.9 x 10^21 cm^-2
Excess significance: 5.4 sigma
Photon index:	     1.96 (+0.14, -0.13)
```
If the light curve continues to decay with a power-law decay index of 1.81, the count rate at T+24 hours will be 2.0 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.2 x 10^-14 (1.3 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/00655262.
This circular is an official product of the Swift-XRT team.
GCN Circular #18292
C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), R. L. C. Starling (U Leicester), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 150911A (trigger #655262) (Starling, et al., GCN Circ. 18280). The BAT ground-calculated position is RA, Dec = 67.428, 5.731 deg which is
```
   RA(J2000)  =  04h 29m 42.6s
   Dec(J2000) = +05d 43' 50.2"
```
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 67%.
The mask-weighted light curve shows a broad peak starting around T-2 sec and ending around T+10 sec. T90 (15-350 keV) is T90 (15-350 keV) is 7.2 +- 0.6 sec (estimated error including systematics).
The time-averaged spectrum from T-1.04 to T+9.61 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 1.02 +- 0.26, and Epeak of 51.6 +- 3.8 keV (chi squared 52.34 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 2.1 +- 0.1 x 10^-06 erg/cm2 and the 1-sec peak flux measured from T+3.90 sec in the 15-150 keV band is 5.2 +- 0.3 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.93 +- 0.05 (chi squared 97.49 for 57 d.o.f.). All the quoted errors are at the 90% confidence level.
The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/655262/BA/
GCN Circular #18293
GRB 150911A: Swift/UVOT Upper Limits
F. E. Marshall (NASA/GSFC) and R. L. C. Starling (U. Leicester) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 150911A 82 s after the BAT trigger (Starling et al., GCN Circ. 18280). No optical afterglow consistent with the enhanced XRT position (Goad et al. GCN Circ. 18283) 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            82          232          147         >20.6
u_FC               294          544          246         >20.2
white               82         1702          400         >21.2
v                  623         1590          117         >18.9
b                  549         1689          117         >19.4
u                  294         1665          343         >20.4
w1                 673         1640          117         >19.1
w2                 772         1565           97         >19.5
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.32 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #18294
S. B. Cenko (NASA/GSFC) and D. A. Perley (DARK) report on behalf of a larger collaboration:
We observed the location of GRB150911A (Starling et al., GCN 18280) with the robotic Palomar 60-inch telescope. Observations were obtained in the r', i', and z' filters beginning at 09:03 UT on 2015 Sep 12 (dt ~ 14.4 hours after the Swift trigger). In stacked images we do not detect any sources within the enhanced XRT error circle (Goad et al., GCN 18283) in any filter. Using comparison point sources from the USNO-B1 catalog for reference, we calculate a limiting magnitude of R > 22.5 in a stacked image at a median time of 09:46 UT on 2015 Sep 12.
GCN Circular #18303
N. R. Tanvir, K. Wiersema (U. Leicester), A. J. Levan (U. Warwick), F. Riddick (ING), C. Bergfors (UCL) report on behalf of a larger collaboration:
We observed the position of GRB 150911A (Starling et al. GCN 18280), using the ACAM instrument on the 4.2m William Herschel Telescope (La Palma, Spain). We acquired imaging in Sloan r, i and z bands, with midpoint 03:46 UT on 12 September 2015 (i.e. 8.9 hours after burst). Data consist of 4x300 seconds exposure time in each filter. No sources are detected within the XRT enhanced position error circle (Goad et al. GCN 18283). Just outside the XRT error circle are two faint sources, detected in all filters:
```
Source 1  at  RA, Dec = 04:29:44.279, +5:44:08.52
Source 2 at   RA, Dec = 04:29:44.120, +5:44:04.34
```
We note that source 1 is slightly extended and provisional photometric calibration gives magnitude r=24.1. Source 2 appears point-like with magnitude r=25.2.
A second epoch observation would be required to ascertain which if any of these sources is associated with the GRB.
GCN Circular #18307
E. Mazaeva (IKI), S. Schmalz (AIP), N. Tungalag (Research Center of Astronomy and Geophysics MAS), A. Volnova (IKI), I.Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:
We observed the field of GRB 150911A (Starling et al., GCN 18280) with ORI-40 telescope of Khureltogot observatory starting on Sep., 11 (UT) 19:03:00, i.e. ~23 minutes after the burst trigger. We do not detect any object within enhanced XRT error circle (Goad et al., GCN 18283). Photometry of the field is following
```
Date UT start       t-T0   Filter Exp.  Upper_Limit (3sigma)
                    (mid, days) (s)

2015-09-11 19:03:00 0.0351 none   45*60 20.9
```
Photometry is base on nearby USNO-B.1 stars
```
USNO-B.1_id R2
0957-0043966 15.54
0957-0043954 16.24
0957-0043961 16.45
```
GCN Circular #18308
M. Andreev (Terskol Branch of INASAN), E. Mazaeva (IKI), A. Sergeev (Terskol Branch of INASAN), A. Volnova (IKI), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:
We observed the field of GRB 150911A (Starling et al., GCN 18280) with Zeiss-600 telescope of Mt. Terskol observatory in R-filter starting on Sep. 11 (UT) 23:26:40. We do not detect any object within enhanced XRT error circle (Goad et al., GCN 18283). Photometry of the field is following
```
Date UT start        t-T0 Filter Exp.   Upper_Limit (3sigma)
                     (mid, days) (s)

2015-09-11 23:26:40 0.2273 R     40*120 21.7
```
Photometry is based on nearby USNO-B.1 stars
```
USNO-B.1_id R2
0957-0043966 15.54
0957-0043954 16.24
0957-0043961 16.45
```
GCN Circular #18309
Yu. Krugly (IA KhNU), V. Shevchenko (IA KhNU), T. Gromakina (IA KhNU), I. Molotov (KIAM), E. Mazaeva (IKI), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:
We observed the field of GRB 150911A (Starling et al., GCN 18280) with 0.7m telescope of Institute of Astronomy, Kharkiv National University starting on Sep. 12 (UT) 01:07:23. We do not detect any object within enhanced XRT error circle (Goad et al., GCN 18283). Photometry of the field is following
```
Date UT start       t-T0   Filter Exp.   Upper_Limit (3sigma)
                    (mid, days)  (s)

2015-09-12 01:07:23 0.2804 R      11*180 20.8
```
Photometry is based on nearby USNO-B.1 stars
```
USNO-B.1_id R2
0957-0043966 15.54
0957-0043954 16.24
0957-0043961 16.45
```
GCN Circular #18313
S. Schmidl (TLS Tautenburg), F. Knust, and J. Greiner (both MPE Garching) report on behalf of the GROND team:
We observed the field of GRB 150911A (Swift trigger 655262; Starling et al, GCN 18280) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008,PASP 120, 405) mounted at the 2.2m MPG telescope at ESO La Silla Observatory (Chile).
Observations started on September 12, 2015, at 05:59 UT, 11.3 hrs after the GRB trigger. They were performed at an average seeing of 2.2" and at an average airmass of 1.8.
We do not detect a source within the 1.7" Swift-XRT error circle reported by Goad et al. (GCN 18283).
Based on total exposures of 33 minutes in g'r'i'z'and 43 minutes in JHK, at a midtime of 12.1 hrs after the burst, we measure the following preliminary upper limits (AB magnitude system):
```
g'> 24.1 mag,
r'> 23.8 mag,
i'> 23.2 mag,
z'> 22.8 mag,
J > 21.6 mag,
H > 21.0 mag, and
K > 19.9 mag.
```
Given upper limits are calibrated against GROND zeropoints as well as 2MASS field stars and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V) = 0.32 mag in the direction of the burst (Schlegel et al. 1998).
GCN Circular #18326
S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik, M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko, A. Kozlova and T. Cline on behalf of the Konus-Wind team, report:
The long-duration GRB 150911A (Swift-BAT trigger #655262: Starling, et al., GCN Circ. 18280; Markwardt , et al., GCN Circ. 18292) was detected by Konus-Wind in the waiting mode.
The burst light curve shows a single pulse with a total duration of ~9 s.
As observed by Konus-Wind, the burst had a fluence of 3.13(-0.20,+0.26)x10^-6 erg/cm2 and a 2.944-s peak flux, measured from ~T0(BAT)+2.5 s, of 4.01(-0.32,+0.59)x10^-7 erg/cm2/s (both in the 20 - 1000 keV energy range).
Fitting the K-W 3-channel time-integrated spectrum (measured from ~T0(BAT)-0.5 s to ~T0(BAT)+8.5 s) by a simple power-law model yields the photon index -2.32(-0.09,+0.09), chi2=0.6/1 dof.
All the quoted errors are estimated at the 1 sigma confidence level. All the presented results are preliminary.
The K-W light curve of this burst is available at http://www.ioffe.rssi.ru/LEA/GRBs/GRB150911A/
[GCN OPS NOTE(16sep15): This circular was delayed ~12 hours in distribution because of an operation mistake at GCN.]

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Jochen Greiner, last update: 17-Sep-2015 [Disclaimer]