Gamma-ray Burst 090904

(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:     Fri 04 Sep 09 01:02:24 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     361830,   Seg_Num: 0
GRB_RA:          100.882d {+06h 43m 32s} (J2000),
                 101.070d {+06h 44m 17s} (current),
                  99.913d {+06h 39m 39s} (1950)
GRB_DEC:         +50.206d {+50d 12' 23"} (J2000),
                 +50.196d {+50d 11' 46"} (current),
                 +50.257d {+50d 15' 24"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       0 [cnts]    Image_Peak=2043 [image_cnts]
TRIGGER_DUR:     64.000 [sec] 
TRIGGER_INDEX:   20000     E_range: 15-50 keV
BKG_INTEN:       0 [cnts]
BKG_TIME:        0.00 SOD {00:00:00.00} UT
BKG_DUR:         0 [sec]
GRB_DATE:        15078 TJD;   247 DOY;   09/09/04
GRB_TIME:        3666.94 SOD {01:01:06.94} UT
GRB_PHI:          12.13 [deg]
GRB_THETA:        29.53 [deg]
SOLN_STATUS:     0x13
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    10.83 [sigma]
MERIT_PARAMS:     +1  +0  +0  +6  +1  +0  +0  +0 -39  +0 
SUN_POSTN:       163.07d {+10h 52m 16s}   +7.20d {+07d 11' 46"}
SUN_DIST:         66.77 [deg]   Sun_angle= 4.1 [hr] (West of Sun)
MOON_POSTN:      335.52d {+22h 22m 06s}   -7.10d {-07d 06' 15"}
MOON_DIST:       117.67 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      165.60, 19.31 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       97.80, 27.06 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Coordinates.  
COMMENTS:        This is an image trigger.  (The RATE_SIGNIF & BKG_{INTEN, TIME, DUR} are undefined.)  
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 = 118.21,20.37 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 04 Sep 09 01:05:06 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     361830,   Seg_Num: 0
GRB_RA:          100.882d {+06h 43m 32s} (J2000),
                 101.070d {+06h 44m 17s} (current),
                  99.913d {+06h 39m 39s} (1950)
GRB_DEC:         +50.206d {+50d 12' 23"} (J2000),
                 +50.196d {+50d 11' 46"} (current),
                 +50.257d {+50d 15' 24"} (1950)
GRB_DATE:        15078 TJD;   247 DOY;   09/09/04
GRB_TIME:        3666.94 SOD {01:01:06.94} UT
TRIGGER_INDEX:   20000
GRB_PHI:          12.13 [deg]
GRB_THETA:        29.53 [deg]
DELTA_TIME:      0.00 [sec]
TRIGGER_DUR:     64.000 [sec] 
SOLN_STATUS:     0x13
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    10.83 [sigma]
LC_URL:          sw00361830000msb.lc
SUN_POSTN:       163.07d {+10h 52m 16s}   +7.20d {+07d 11' 43"}
SUN_DIST:         66.77 [deg]   Sun_angle= 4.1 [hr] (West of Sun)
MOON_POSTN:      335.55d {+22h 22m 11s}   -7.09d {-07d 05' 40"}
MOON_DIST:       117.65 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      165.60, 19.31 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       97.80, 27.06 [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 an image 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 = 118.21,20.37 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 04 Sep 09 01:06:09 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     361830,   Seg_Num: 0
GRB_RA:          100.8816d {+06h 43m 31.58s} (J2000),
                 101.0690d {+06h 44m 16.56s} (current),
                  99.9121d {+06h 39m 38.89s} (1950)
GRB_DEC:         +50.2040d {+50d 12' 14.4"} (J2000),
                 +50.1937d {+50d 11' 37.4"} (current),
                 +50.2542d {+50d 15' 15.2"} (1950)
GRB_ERROR:       5.2 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.71e-09 [erg/cm2/sec]
GRB_SIGNIF:      8.18 [sigma]
IMG_START_DATE:  15078 TJD;   247 DOY;   09/09/04
IMG_START_TIME:  3938.63 SOD {01:05:38.63} UT,   271.7 [sec] since BAT Trigger Time
TAM[0-3]:        327.63 237.23 261.57 243.28
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       163.07d {+10h 52m 16s}   +7.20d {+07d 11' 42"}
SUN_DIST:         66.77 [deg]   Sun_angle= 4.1 [hr] (West of Sun)
MOON_POSTN:      335.55d {+22h 22m 13s}   -7.09d {-07d 05' 26"}
MOON_DIST:       117.64 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      165.60, 19.31 [deg] galactic lon,lat of the burst
ECL_COORDS:       97.80, 27.06 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 0.14 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 04 Sep 09 01:06:23 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     361830,   Seg_Num: 0
GRB_RA:          100.8816d {+06h 43m 31.5s} (J2000),
                 101.0690d {+06h 44m 16.5s} (current),
                  99.9121d {+06h 39m 38.8s} (1950)
GRB_DEC:         +50.2040d {+50d 12' 14.4"} (J2000),
                 +50.1937d {+50d 11' 37.4"} (current),
                 +50.2542d {+50d 15' 15.2"} (1950)
GRB_ERROR:       5.0 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       67 [cnts]
IMG_START_DATE:  15078 TJD;   247 DOY;   09/09/04
IMG_START_TIME:  3938.63 SOD {01:05:38.63} UT,   271.7 [sec] since BAT Trigger Time
CENTROID_X:      319.92,  raw= 320  [pixels]
CENTROID_Y:      296.26,  raw= 296  [pixels]
ROLL:            107.44 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -4.09
GRB_POS_XRT_Z:   41.54
IMAGE_URL:       sw00361830000msxps_rw.img
SUN_POSTN:       163.07d {+10h 52m 17s}   +7.19d {+07d 11' 42"}
SUN_DIST:         66.77 [deg]   Sun_angle= 4.1 [hr] (West of Sun)
MOON_POSTN:      335.56d {+22h 22m 13s}   -7.09d {-07d 05' 23"}
MOON_DIST:       117.64 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      165.60, 19.31 [deg] galactic lon,lat of the burst
ECL_COORDS:       97.80, 27.06 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 04 Sep 09 01:06:29 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     361830,   Seg_Num: 0
GRB_RA:          100.8816d {+06h 43m 31.5s} (J2000),
                 101.0690d {+06h 44m 16.5s} (current),
                  99.9121d {+06h 39m 38.8s} (1950)
GRB_DEC:         +50.2040d {+50d 12' 14.4"} (J2000),
                 +50.1937d {+50d 11' 37.4"} (current),
                 +50.2542d {+50d 15' 15.2"} (1950)
GRB_ERROR:       5.0 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       67 [cnts]
IMG_START_DATE:  15078 TJD;   247 DOY;   09/09/04
IMG_START_TIME:  3938.63 SOD {01:05:38.63} UT,   271.7 [sec] since BAT Trigger Time
CENTROID_X:      319.92,  raw= 320  [pixels]
CENTROID_Y:      296.26,  raw= 296  [pixels]
ROLL:            107.44 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -4.09
GRB_POS_XRT_Z:   41.54
IMAGE_URL:       sw00361830000msxps_rw.img
SUN_POSTN:       163.07d {+10h 52m 17s}   +7.19d {+07d 11' 42"}
SUN_DIST:         66.77 [deg]   Sun_angle= 4.1 [hr] (West of Sun)
MOON_POSTN:      335.56d {+22h 22m 13s}   -7.09d {-07d 05' 21"}
MOON_DIST:       117.64 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      165.60, 19.31 [deg] galactic lon,lat of the burst
ECL_COORDS:       97.80, 27.06 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 04 Sep 09 01:06:59 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     361830,   Seg_Num: 0
POINT_RA:        100.898d {+06h 43m 36s} (J2000)
POINT_DEC:       +50.199d {+50d 11' 55"} (J2000)
POINT_ROLL:      107.441d
IMG_START_DATE:  15078 TJD;   247 DOY;   09/09/04
IMG_START_TIME:  3808.27 SOD {01:03:28.27} UT,   141.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.434
N_STARS:         78
X_OFFSET:        394 [pixels]
Y_OFFSET:        588 [pixels]
X_MAX:           1353 [pixels]
Y_MAX:           1547 [pixels]
DET_THRESH:      15
PHOTO_THRESH:    8
SL_URL:          sw00361830000msufc0141.fits
SUN_POSTN:       163.07d {+10h 52m 17s}   +7.19d {+07d 11' 41"}
SUN_DIST:         66.76 [deg]   Sun_angle= 4.1 [hr] (West of Sun)
MOON_POSTN:      335.56d {+22h 22m 14s}   -7.09d {-07d 05' 15"}
MOON_DIST:       117.64 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      165.61, 19.32 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       97.81, 27.05 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 04 Sep 09 01:07:43 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     361830,   Seg_Num: 0
POINT_RA:        100.898d {+06h 43m 36s} (J2000)
POINT_DEC:       +50.199d {+50d 11' 55"} (J2000)
ROLL:            107.441d
IMG_START_DATE:  15078 TJD;   247 DOY;   09/09/04
IMG_START_TIME:  3808.27 SOD {01:03:28.27} UT,   141.3 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     273719013
X_OFFSET:        713 [pixels]
Y_OFFSET:        907 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       873
Y_GRB_POS:       1067
BINNING_INDEX:   1
IM_URL:          sw00361830000msuni0147.fits
SUN_POSTN:       163.07d {+10h 52m 17s}   +7.19d {+07d 11' 41"}
SUN_DIST:         66.76 [deg]   Sun_angle= 4.1 [hr] (West of Sun)
MOON_POSTN:      335.57d {+22h 22m 16s}   -7.09d {-07d 05' 05"}
MOON_DIST:       117.64 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      165.61, 19.32 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       97.81, 27.05 [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 04 Sep 09 01:06:59 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     361830,   Seg_Num: 0
POINT_RA:        100.898d {+06h 43m 36s} (J2000)
POINT_DEC:       +50.199d {+50d 11' 55"} (J2000)
POINT_ROLL:      107.441d
IMG_START_DATE:  15078 TJD;   247 DOY;   09/09/04
IMG_START_TIME:  3808.27 SOD {01:03:28.27} UT,   141.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.434
N_STARS:         78
X_OFFSET:        394 [pixels]
Y_OFFSET:        588 [pixels]
X_MAX:           1353 [pixels]
Y_MAX:           1547 [pixels]
DET_THRESH:      15
PHOTO_THRESH:    8
SL_URL:          sw00361830000msufc0141.fits
SUN_POSTN:       163.07d {+10h 52m 17s}   +7.19d {+07d 11' 41"}
SUN_DIST:         66.76 [deg]   Sun_angle= 4.1 [hr] (West of Sun)
MOON_POSTN:      335.56d {+22h 22m 14s}   -7.09d {-07d 05' 15"}
MOON_DIST:       117.64 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      165.61, 19.32 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       97.81, 27.05 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 04 Sep 09 01:13:20 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     361830,   Seg_Num: 0
POINT_RA:        100.900d {+06h 43m 36s} (J2000)
POINT_DEC:       +50.201d {+50d 12' 05"} (J2000)
POINT_ROLL:      107.442d
IMG_START_DATE:  15078 TJD;   247 DOY;   09/09/04
IMG_START_TIME:  3966.35 SOD {01:06:06.35} UT,   299.4 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.442
N_STARS:         182
X_OFFSET:        154 [pixels]
Y_OFFSET:        348 [pixels]
X_MAX:           1593 [pixels]
Y_MAX:           1787 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00361830000msufc0299.fits
SUN_POSTN:       163.07d {+10h 52m 18s}   +7.19d {+07d 11' 36"}
SUN_DIST:         66.76 [deg]   Sun_angle= 4.1 [hr] (West of Sun)
MOON_POSTN:      335.61d {+22h 22m 26s}   -7.06d {-07d 03' 51"}
MOON_DIST:       117.60 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      165.61, 19.32 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       97.81, 27.06 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 04 Sep 09 01:13:20 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     361830,   Seg_Num: 0
POINT_RA:        100.900d {+06h 43m 36s} (J2000)
POINT_DEC:       +50.201d {+50d 12' 05"} (J2000)
POINT_ROLL:      107.442d
IMG_START_DATE:  15078 TJD;   247 DOY;   09/09/04
IMG_START_TIME:  3966.35 SOD {01:06:06.35} UT,   299.4 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.442
N_STARS:         182
X_OFFSET:        154 [pixels]
Y_OFFSET:        348 [pixels]
X_MAX:           1593 [pixels]
Y_MAX:           1787 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00361830000msufc0299.fits
SUN_POSTN:       163.07d {+10h 52m 18s}   +7.19d {+07d 11' 36"}
SUN_DIST:         66.76 [deg]   Sun_angle= 4.1 [hr] (West of Sun)
MOON_POSTN:      335.61d {+22h 22m 26s}   -7.06d {-07d 03' 51"}
MOON_DIST:       117.60 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      165.61, 19.32 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       97.81, 27.06 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 04 Sep 09 01:13:59 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     361830,   Seg_Num: 0
POINT_RA:        100.900d {+06h 43m 36s} (J2000)
POINT_DEC:       +50.201d {+50d 12' 05"} (J2000)
POINT_ROLL:      107.442d
IMG_START_DATE:  15078 TJD;   247 DOY;   09/09/04
IMG_START_TIME:  3966.35 SOD {01:06:06.35} UT,   299.4 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.442
N_STARS:         182
X_OFFSET:        154 [pixels]
Y_OFFSET:        348 [pixels]
X_MAX:           1593 [pixels]
Y_MAX:           1787 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00361830000msufc0299.fits
SUN_POSTN:       163.07d {+10h 52m 18s}   +7.19d {+07d 11' 35"}
SUN_DIST:         66.76 [deg]   Sun_angle= 4.1 [hr] (West of Sun)
MOON_POSTN:      335.61d {+22h 22m 27s}   -7.06d {-07d 03' 42"}
MOON_DIST:       117.59 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      165.61, 19.32 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       97.81, 27.06 [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 04 Sep 09 01:14:09 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     361830,   Seg_Num: 0
POINT_RA:        100.900d {+06h 43m 36s} (J2000)
POINT_DEC:       +50.201d {+50d 12' 05"} (J2000)
ROLL:            107.442d
IMG_START_DATE:  15078 TJD;   247 DOY;   09/09/04
IMG_START_TIME:  3966.35 SOD {01:06:06.35} UT,   299.4 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     273719171
X_OFFSET:        713 [pixels]
Y_OFFSET:        907 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       873
Y_GRB_POS:       1067
BINNING_INDEX:   1
IM_URL:          sw00361830000msuni0305.fits
SUN_POSTN:       163.07d {+10h 52m 18s}   +7.19d {+07d 11' 35"}
SUN_DIST:         66.76 [deg]   Sun_angle= 4.1 [hr] (West of Sun)
MOON_POSTN:      335.62d {+22h 22m 28s}   -7.06d {-07d 03' 40"}
MOON_DIST:       117.59 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      165.61, 19.32 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       97.81, 27.06 [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 04 Sep 09 01:14:37 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     361830,   Seg_Num: 0
POINT_RA:        100.900d {+06h 43m 36s} (J2000)
POINT_DEC:       +50.201d {+50d 12' 05"} (J2000)
ROLL:            107.442d
IMG_START_DATE:  15078 TJD;   247 DOY;   09/09/04
IMG_START_TIME:  3966.35 SOD {01:06:06.35} UT,   299.4 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     273719171
X_OFFSET:        713 [pixels]
Y_OFFSET:        907 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       873
Y_GRB_POS:       1067
BINNING_INDEX:   1
IM_URL:          sw00361830000msuni0305.fits
SUN_POSTN:       163.07d {+10h 52m 18s}   +7.19d {+07d 11' 34"}
SUN_DIST:         66.76 [deg]   Sun_angle= 4.1 [hr] (West of Sun)
MOON_POSTN:      335.62d {+22h 22m 29s}   -7.06d {-07d 03' 34"}
MOON_DIST:       117.59 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      165.61, 19.32 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       97.81, 27.06 [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 #9879
M. Perri (ASDC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU), V. D'Elia (ASDC), S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC), M. H. Siegel (PSU), M. Stamatikos (OSU/NASA/GSFC), M. A. Stark (PSU) and T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team:
At 01:01:06 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 090904 (trigger=361830). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 100.882, +50.206 which is
```
   RA(J2000) = 06h 43m 32s
   Dec(J2000) = +50d 12' 23"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a small peak at T_zero and then two large peaks at T+130 and T+175 sec with a duration of at least 200 sec. The peak count rate was ~2500 counts/sec (15-350 keV), at ~T+130 sec after the trigger.
The XRT began observing the field at 01:05:38.6 UT, 271.7 seconds after the BAT trigger. XRT found a bright, uncatalogued, fading X-ray source located at RA, Dec 100.8816, +50.2040 which is equivalent to:
```
   RA(J2000)  = 06h 43m 31.58s
   Dec(J2000) = +50d 12' 14.4"
```
with an uncertainty of 5.2 arcseconds (radius, 90% containment). This location is 7.3 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.
The XRT prompt light curve shows a large flare peaking about 30s after the start of the XRT observations.
The initial flux in the 2.5 s image was 1.71e-09 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 141 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. Because part of the 2.7'x2.7' sub-image was not received, the overlap with the XRT error circle is uncertain. 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 0.10.
Burst Advocate for this burst is M. Perri (perri AT asdc.asi.it). 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 04 Sep 09 01:19:36 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     361830,   Seg_Num: 0
POINT_RA:        100.900d {+06h 43m 36s} (J2000)
POINT_DEC:       +50.202d {+50d 12' 05"} (J2000)
POINT_ROLL:      107.442d
IMG_START_DATE:  15078 TJD;   247 DOY;   09/09/04
IMG_START_TIME:  4545.21 SOD {01:15:45.21} UT,   878.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        6.478
N_STARS:         190
X_OFFSET:        154 [pixels]
Y_OFFSET:        348 [pixels]
X_MAX:           1593 [pixels]
Y_MAX:           1787 [pixels]
DET_THRESH:      22
PHOTO_THRESH:    13
SL_URL:          sw00361830000msufc0878.fits
SUN_POSTN:       163.08d {+10h 52m 18s}   +7.19d {+07d 11' 30"}
SUN_DIST:         66.77 [deg]   Sun_angle= 4.1 [hr] (West of Sun)
MOON_POSTN:      335.66d {+22h 22m 38s}   -7.04d {-07d 02' 28"}
MOON_DIST:       117.55 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      165.61, 19.32 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       97.81, 27.06 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 04 Sep 09 01:19:36 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     361830,   Seg_Num: 0
POINT_RA:        100.900d {+06h 43m 36s} (J2000)
POINT_DEC:       +50.202d {+50d 12' 05"} (J2000)
POINT_ROLL:      107.442d
IMG_START_DATE:  15078 TJD;   247 DOY;   09/09/04
IMG_START_TIME:  4545.21 SOD {01:15:45.21} UT,   878.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        6.478
N_STARS:         190
X_OFFSET:        154 [pixels]
Y_OFFSET:        348 [pixels]
X_MAX:           1593 [pixels]
Y_MAX:           1787 [pixels]
DET_THRESH:      22
PHOTO_THRESH:    13
SL_URL:          sw00361830000msufc0878.fits
SUN_POSTN:       163.08d {+10h 52m 18s}   +7.19d {+07d 11' 30"}
SUN_DIST:         66.77 [deg]   Sun_angle= 4.1 [hr] (West of Sun)
MOON_POSTN:      335.66d {+22h 22m 38s}   -7.04d {-07d 02' 28"}
MOON_DIST:       117.55 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      165.61, 19.32 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       97.81, 27.06 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 04 Sep 09 01:20:17 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     361830,   Seg_Num: 0
POINT_RA:        100.900d {+06h 43m 36s} (J2000)
POINT_DEC:       +50.202d {+50d 12' 05"} (J2000)
POINT_ROLL:      107.442d
IMG_START_DATE:  15078 TJD;   247 DOY;   09/09/04
IMG_START_TIME:  4545.21 SOD {01:15:45.21} UT,   878.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        6.478
N_STARS:         190
X_OFFSET:        154 [pixels]
Y_OFFSET:        348 [pixels]
X_MAX:           1593 [pixels]
Y_MAX:           1787 [pixels]
DET_THRESH:      22
PHOTO_THRESH:    13
SL_URL:          sw00361830000msufc0878.fits
SUN_POSTN:       163.08d {+10h 52m 19s}   +7.19d {+07d 11' 29"}
SUN_DIST:         66.77 [deg]   Sun_angle= 4.1 [hr] (West of Sun)
MOON_POSTN:      335.66d {+22h 22m 39s}   -7.04d {-07d 02' 19"}
MOON_DIST:       117.54 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      165.61, 19.32 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       97.81, 27.06 [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 04 Sep 09 01:21:54 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     361830,   Seg_Num: 0
POINT_RA:        100.900d {+06h 43m 36s} (J2000)
POINT_DEC:       +50.202d {+50d 12' 05"} (J2000)
ROLL:            107.442d
IMG_START_DATE:  15078 TJD;   247 DOY;   09/09/04
IMG_START_TIME:  4545.21 SOD {01:15:45.21} UT,   878.3 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     273719750
X_OFFSET:        713 [pixels]
Y_OFFSET:        907 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       873
Y_GRB_POS:       1067
BINNING_INDEX:   1
IM_URL:          sw00361830000msuni0884.fits
SUN_POSTN:       163.08d {+10h 52m 19s}   +7.19d {+07d 11' 28"}
SUN_DIST:         66.77 [deg]   Sun_angle= 4.1 [hr] (West of Sun)
MOON_POSTN:      335.68d {+22h 22m 42s}   -7.03d {-07d 01' 58"}
MOON_DIST:       117.53 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      165.61, 19.32 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       97.81, 27.06 [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 04 Sep 09 01:22:20 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     361830,   Seg_Num: 0
POINT_RA:        100.900d {+06h 43m 36s} (J2000)
POINT_DEC:       +50.202d {+50d 12' 05"} (J2000)
ROLL:            107.442d
IMG_START_DATE:  15078 TJD;   247 DOY;   09/09/04
IMG_START_TIME:  4545.21 SOD {01:15:45.21} UT,   878.3 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     273719750
X_OFFSET:        713 [pixels]
Y_OFFSET:        907 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       873
Y_GRB_POS:       1067
BINNING_INDEX:   1
IM_URL:          sw00361830000msuni0884.fits
SUN_POSTN:       163.08d {+10h 52m 19s}   +7.19d {+07d 11' 27"}
SUN_DIST:         66.77 [deg]   Sun_angle= 4.1 [hr] (West of Sun)
MOON_POSTN:      335.68d {+22h 22m 43s}   -7.03d {-07d 01' 52"}
MOON_DIST:       117.53 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      165.61, 19.32 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       97.81, 27.06 [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 04 Sep 09 01:27:06 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     361830,   Seg_Num: 0
GRB_RA:          100.8858d {+06h 43m 32.59s} (J2000),
                 101.0732d {+06h 44m 17.57s} (current),
                  99.9163d {+06h 39m 39.90s} (1950)
GRB_DEC:         +50.2038d {+50d 12' 13.6"} (J2000),
                 +50.1935d {+50d 11' 36.7"} (current),
                 +50.2541d {+50d 15' 14.6"} (1950)
GRB_ERROR:       2.3 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  15078 TJD;   247 DOY;   09/09/04
IMG_START_TIME:  4130.00 SOD {01:08:50.00} UT,   85471.9 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       163.08d {+10h 52m 20s}   +7.19d {+07d 11' 23"}
SUN_DIST:         66.78 [deg]   Sun_angle= 4.1 [hr] (West of Sun)
MOON_POSTN:      335.72d {+22h 22m 52s}   -7.01d {-07d 00' 49"}
MOON_DIST:       117.48 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      165.61, 19.31 [deg] galactic lon,lat of the burst
ECL_COORDS:       97.80, 27.06 [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

GCN Circular #9880
S. B. Pandey (U Mich), W. Rujopakarn (Steward), W. Zheng (U Mich) report on behalf of the ROTSE collaboration:
ROTSE-IIId, located at the Turkish National Observatory at Bakirlitepe, Turkey, responded to GRB 090904A (Swift trigger 361830; Perri M., GCN 9879), producing images beginning 9.5 s after the GCN notice time. An automated response took the first image at 01:02:31.6 UT, 84.7 s after the burst, and during the gamma-ray emission, under fair conditions. We took 10 5-sec, 10 20-sec and 10 60-sec exposures. These unfiltered images are calibrated relative to USNO A2.0 (R). Imaging is on going.
Comparison to the DSS (second epoch) reveals no new sources within the 3-sigma Swift/BAT error circle or the XRT error circle, for both single images and coadding into sets of 10. Individual images have limiting magnitudes ranging from 15.8-16.6; we set the following specific limits.
```
start UT       end UT      t_exp(s)   mlim   t_start-tGRB(s)  Coadd?
--------------------------------------------------------------------
01:02:31.5   01:02:36.5         5     15.8           84.6       N
01:04:48.1   01:09:27.0       278     17.8          221.2       Y
```

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 04 Sep 09 01:07:28 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     361830,   Seg_Num: 0
POINT_RA:        100.898d {+06h 43m 36s} (J2000)
POINT_DEC:       +50.199d {+50d 11' 55"} (J2000)
POINT_ROLL:      107.441d
IMG_START_DATE:  15078 TJD;   247 DOY;   09/09/04
IMG_START_TIME:  3808.27 SOD {01:03:28.27} UT,   141.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.434
N_STARS:         78
X_OFFSET:        394 [pixels]
Y_OFFSET:        588 [pixels]
X_MAX:           1353 [pixels]
Y_MAX:           1547 [pixels]
DET_THRESH:      15
PHOTO_THRESH:    8
SL_URL:          sw00361830000msufc0141.fits
SUN_POSTN:       163.07d {+10h 52m 17s}   +7.19d {+07d 11' 41"}
SUN_DIST:         66.76 [deg]   Sun_angle= 4.1 [hr] (West of Sun)
MOON_POSTN:      335.56d {+22h 22m 15s}   -7.09d {-07d 05' 08"}
MOON_DIST:       117.64 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      165.61, 19.32 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       97.81, 27.05 [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 04 Sep 09 01:08:09 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     361830,   Seg_Num: 0
POINT_RA:        100.898d {+06h 43m 36s} (J2000)
POINT_DEC:       +50.199d {+50d 11' 55"} (J2000)
ROLL:            107.441d
IMG_START_DATE:  15078 TJD;   247 DOY;   09/09/04
IMG_START_TIME:  3808.27 SOD {01:03:28.27} UT,   141.3 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     273719013
X_OFFSET:        713 [pixels]
Y_OFFSET:        907 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       873
Y_GRB_POS:       1067
BINNING_INDEX:   1
IM_URL:          sw00361830000msuni0147.fits
SUN_POSTN:       163.07d {+10h 52m 17s}   +7.19d {+07d 11' 40"}
SUN_DIST:         66.76 [deg]   Sun_angle= 4.1 [hr] (West of Sun)
MOON_POSTN:      335.57d {+22h 22m 17s}   -7.08d {-07d 05' 00"}
MOON_DIST:       117.64 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      165.61, 19.32 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       97.81, 27.05 [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 #9884
D. Malesani (DARK/NBI), P. Jakobsson (U. Iceland), N. Tanvir (U. Leicester) and I. Ilyin (AIP) report on behalf of a larger collaboration:
We observed the field of GRB 090904A (Perri et al., GCN 9879) with the Nordic Optical Telescope equipped with StanCam. Observations were carried out on 2009 Sept 4.17 (3.1 hr after the GRB) in the R- and I-bands. No objects are detected inside the XRT error circle to a limit of R > 23. However, just outside the error circle at
```
RA(J2000)  =  06:43:32.33
Dec(J2000) = +50:12:12.4
```
there is an object with R = 22 +/- 0.2 mag (calibrated against several nearby USNO-B1 stars). If weather permits, further observations are planned tonight to estimate whether the object is fading.
GCN Circular #9885
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team.
Using 1030 s of XRT Photon Counting mode data and 1 UVOT images for GRB 090904A, 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 = 100.88052, +50.20366 which is equivalent to:
```
RA (J2000): 06h 43m 31.33s
Dec (J2000): +50d 12' 13.2"
```
with an uncertainty of 2.0 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 #9886
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
The automatic enhanced XRT position (GCN 9885) was incorrect and should be disregarded. The position was obtained by averaging all the PC data from the first orbit, however the degree of pile up in this period changes by much more than is normal (see the light curve at: http://www.swift.ac.uk/xrt_curves/00361830/). As a result, the PSF of the image did not match any of our calibrated PSFs. We apologise for any confusion.
The best XRT position available is the enhanced SPER position, which was distributed as an XRT Position Update GCN notice about at 01:27 UT. This position is RA, Dec = 100.8858, 50.2038, which corresponds to
```
RA(J2000.0) =  06h 43m 32.59s
Dec (J2000.0) = +50d 12' 13.6"
```
with an uncertainty of 2.3 arcsec (radius, 90% confidence).
This circular is an official product of the Swift-XRT team.
GCN Circular #9888
D. M. Palmer (LANL), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), M. Perri (ASDC), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team):
Using the data set from T-60 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 090904A (trigger #361830) (Perri, et al., GCN Circ. 9879). The BAT ground-calculated position is RA, Dec = 100.855, 50.235 deg, which is
```
   RA(J2000)  =  06h 43m 25.2s 
   Dec(J2000) = +50d 14' 06.9" 
```
with an uncertainty of 3.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 75%.
The mask-weighted light curve shows low level emission starting at ~T-40 sec, with a small peak at ~T+5 sec. Then there was a larger peak at ~T+50 sec, and then the largest peak (FRED-like) starting at ~T+123 sec, peaking at ~T+128 sec. Riding on that tail is a peak ~T+173. The event is over in the BAT energy band at ~T+240 sec. T90 (15-350 keV) is 122 +- 10 sec (estimated error including systematics).
The time-averaged spectrum from T+29.3 to T+186.3 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.01 +- 0.10. The fluence in the 15-150 keV band is 3.0 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+127.07 sec in the 15-150 keV band is 1.9 +- 0.2 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/361830/BA/
GCN Circular #9891
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team.
With 6 ks of XRT data, and 5 UVOT images from recent data downlinks we have generated an enhanced XRT position for GRB 090904A, which does not include the problematic first image and is thus reliable.
The enhanced position is RA, Dec = 100.88480, +50.20300 which is equivalent to:
```
RA (J2000): 06h 43m 32.35s
Dec (J2000): +50d 12' 10.8"
```
with an uncertainty of 1.6 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 is an official product of the Swift-XRT team.
GCN Circular #9894
M. Perri, V. D'Elia, G. Stratta (ASDC) report on behalf of the Swift-XRT team:
We have analysed the first 12 ks of XRT data for GRB 090904A (Perri et al., GCN Circ. 9879), from 134 s to 29.6 ks after the BAT trigger. The enhanced XRT position for this burst was given by Evans (GCN. Circ. 9891).
During the first Swift orbit, the light-curve shows a steep decay with a large superimposed flare peaking at about T+300 s. Starting from T+1000 s, the curve is well described by a broken power-law model with temporal decay indices alpha1=0.2+/-0.1, alpha2=0.9+/-0.3 and a temporal break at around T+12 ks.
A spectrum extracted from the PC mode data from T+460 s to T+29.6 ks can be fitted with an absorbed power-law model with a photon spectral index of 2.46 (+0.16,-0.26) and an absorption column density of 1.03 (+0.66,-0.64)e21 cm-2 in excess of the Galactic value of 9.3e20 cm-2 (Kalberla et al. 2005). The counts-to-observed (-unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.3e-11 (6.2e-11) erg cm-2 count-1. Errors are given at the 90% confidence level.
If the light curve continues to decay with a power-law index of 0.9, the count rate at T+24 hours will be 6e-3 count s-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.0e-13 (3.7e-13) erg cm-2 s-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00361830.
This circular is an official product of the Swift-XRT team.
GCN Circular #9899
T. A. Pritchard (PSU), C. A. Swenson (PSU) and M. Perri (ASDC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of GRB 090904A, 141 seconds after the BAT trigger (M. Perri et al., GCN Circ. 9879). We do not detect any source at the UVOT-enhanced XRT position (M.R. Goad, GCN Circ. 9885).
The 3-sigma upper limits for the exposures are:
```
Filter   T_start(s)   T_stop(s)   Exp(s)  Mag (3-sigma upper limit)
-------------------------------------------------------------
white      141      	1189       341      > 21.57
v          629       	1078        58      > 18.72
b          555          1177        58      > 19.59
u          299       	1152       285      > 20.43
uvw1	   679		1127	    58      > 19.11
uvm2	   827		847	    19      > 17.61
uvw2	   605		1054	    58      > 19.17
-------------------------------------------------------------
```
The quoted upper limits have not been corrected for the expected Galactic extinction corresponding to a reddeningalong the line of sight of E_(B-V) = 0.1 mag (Schlegel et al., 1998, ApJS, 500, 525). All photometry is on the UVOT photometric system described in Poole et al. (2008, MNRAS, 383, 627).
GCN Report 245.1
GCN_Report 245.1 has been posted: http://gcn.gsfc.nasa.gov/reports/report_245_1.pdf by M. Perri at ASDC titled: "Final Results on Swift GRB 090904A"
GCN Circular #10000
Daniele Malesani (DARK/NBI), Pall Jakobsson (Univ. Iceland), and Ilya Ilyin (AIP), report on behalf of a larger collaboration:
We observed again the field of GRB 090904A (Perri et al., GCN 9879) with the NOT equipped with StanCam. Observations were carried out in the R band, for a total exposure time of 30 min, with a mean time September 6.218 UT (2.176 days after the GRB trigger).
The object identified in our previous epoch of imaging (Malesani et al., GCN 9884) has clearly faded and is hardly detectable, if at all. A faint source is visible at its position, with magnitude R = 24.0 +- 0.3. If real, the inferred decay slope is alpha = 0.55 +- 0.12, assuming F(t) propto t^-alpha. The value of alpha is shallower than usually found at late times, and may indicate some host contribution or an unusual light curve.
The position of the transient is consistent with the latest available UVOT-enhanced XRT position (Goad et al., GCN 9885; see also http://www.swift.ac.uk/xrt_positions/index.php). We thus identify the object as the optical afterglow of GRB 090904A.
A finding chart comparing the two epochs can be found at the following URL:
http://www.astro.ku.dk/~malesani/GRB/090904A/GRB090904A_finder_NOT.jpg

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Jochen Greiner, last update: 08-Oct-2009 [Disclaimer]