Gamma-ray Burst 100823A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 23 Aug 10 17:25:50 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     432420,   Seg_Num: 0
GRB_RA:           20.703d {+01h 22m 49s} (J2000),
                  20.842d {+01h 23m 22s} (current),
                  20.053d {+01h 20m 13s} (1950)
GRB_DEC:          +5.842d {+05d 50' 31"} (J2000),
                  +5.897d {+05d 53' 51"} (current),
                  +5.581d {+05d 34' 52"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       4979 [cnts]    Image_Peak=287 [image_cnts]
TRIGGER_DUR:     1.024 [sec] 
TRIGGER_INDEX:   137     E_range: 15-50 keV
BKG_INTEN:       30637 [cnts]
BKG_TIME:        62721.89 SOD {17:25:21.89} UT
BKG_DUR:         8 [sec]
GRB_DATE:        15431 TJD;   235 DOY;   10/08/23
GRB_TIME:        62735.71 SOD {17:25:35.71} UT
GRB_PHI:         -174.59 [deg]
GRB_THETA:        23.97 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     15.84 [sigma]
IMAGE_SIGNIF:    10.50 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +1  +0  +0  +0 +63  +0 
SUN_POSTN:       152.54d {+10h 10m 10s}  +11.30d {+11d 18' 15"}
SUN_DIST:        128.96 [deg]   Sun_angle= 8.8 [hr] (West of Sun)
MOON_POSTN:      321.15d {+21h 24m 35s}  -11.85d {-11d 51' 17"}
MOON_DIST:        61.96 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      137.05,-56.17 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       21.32, -2.67 [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 = 177.66,-17.59 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 23 Aug 10 17:27:14 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     432420,   Seg_Num: 0
GRB_RA:           20.7029d {+01h 22m 48.69s} (J2000),
                  20.8414d {+01h 23m 21.94s} (current),
                  20.0527d {+01h 20m 12.64s} (1950)
GRB_DEC:          +5.8319d {+05d 49' 54.8"} (J2000),
                  +5.8873d {+05d 53' 14.2"} (current),
                  +5.5709d {+05d 34' 15.3"} (1950)
GRB_ERROR:       6.2 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       5.93e-10 [erg/cm2/sec]
GRB_SIGNIF:      5.65 [sigma]
IMG_START_DATE:  15431 TJD;   235 DOY;   10/08/23
IMG_START_TIME:  62804.57 SOD {17:26:44.57} UT,   68.9 [sec] since BAT Trigger Time
TAM[0-3]:        327.69 237.23 261.51 243.78
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       152.54d {+10h 10m 10s}  +11.30d {+11d 18' 14"}
SUN_DIST:        128.96 [deg]   Sun_angle= 8.8 [hr] (West of Sun)
MOON_POSTN:      321.16d {+21h 24m 38s}  -11.85d {-11d 51' 01"}
MOON_DIST:        61.94 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      137.05,-56.18 [deg] galactic lon,lat of the burst
ECL_COORDS:       21.31, -2.67 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 0.60 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 23 Aug 10 17:27:26 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     432420,   Seg_Num: 0
GRB_RA:           20.7029d {+01h 22m 48.6s} (J2000),
                  20.8414d {+01h 23m 21.9s} (current),
                  20.0527d {+01h 20m 12.6s} (1950)
GRB_DEC:          +5.8319d {+05d 49' 54.8"} (J2000),
                  +5.8873d {+05d 53' 14.2"} (current),
                  +5.5709d {+05d 34' 15.3"} (1950)
GRB_ERROR:       6.1 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       32 [cnts]
IMG_START_DATE:  15431 TJD;   235 DOY;   10/08/23
IMG_START_TIME:  62804.57 SOD {17:26:44.57} UT,   68.9 [sec] since BAT Trigger Time
CENTROID_X:      301.51,  raw= 302  [pixels]
CENTROID_Y:      282.26,  raw= 282  [pixels]
ROLL:            70.24 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -37.08
GRB_POS_XRT_Z:   -1.84
IMAGE_URL:       sw00432420000msxps_rw.img
SUN_POSTN:       152.54d {+10h 10m 10s}  +11.30d {+11d 18' 14"}
SUN_DIST:        128.96 [deg]   Sun_angle= 8.8 [hr] (West of Sun)
MOON_POSTN:      321.16d {+21h 24m 38s}  -11.85d {-11d 51' 00"}
MOON_DIST:        61.94 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      137.05,-56.18 [deg] galactic lon,lat of the burst
ECL_COORDS:       21.31, -2.67 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 23 Aug 10 17:27:31 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     432420,   Seg_Num: 0
GRB_RA:           20.7029d {+01h 22m 48.6s} (J2000),
                  20.8414d {+01h 23m 21.9s} (current),
                  20.0527d {+01h 20m 12.6s} (1950)
GRB_DEC:          +5.8319d {+05d 49' 54.8"} (J2000),
                  +5.8873d {+05d 53' 14.2"} (current),
                  +5.5709d {+05d 34' 15.3"} (1950)
GRB_ERROR:       6.1 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       32 [cnts]
IMG_START_DATE:  15431 TJD;   235 DOY;   10/08/23
IMG_START_TIME:  62804.57 SOD {17:26:44.57} UT,   68.9 [sec] since BAT Trigger Time
CENTROID_X:      301.51,  raw= 302  [pixels]
CENTROID_Y:      282.26,  raw= 282  [pixels]
ROLL:            70.24 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -37.08
GRB_POS_XRT_Z:   -1.84
IMAGE_URL:       sw00432420000msxps_rw.img
SUN_POSTN:       152.54d {+10h 10m 10s}  +11.30d {+11d 18' 14"}
SUN_DIST:        128.96 [deg]   Sun_angle= 8.8 [hr] (West of Sun)
MOON_POSTN:      321.16d {+21h 24m 38s}  -11.85d {-11d 50' 58"}
MOON_DIST:        61.94 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      137.05,-56.18 [deg] galactic lon,lat of the burst
ECL_COORDS:       21.31, -2.67 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 23 Aug 10 17:29:31 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     432420,   Seg_Num: 0
GRB_RA:           20.703d {+01h 22m 49s} (J2000),
                  20.842d {+01h 23m 22s} (current),
                  20.053d {+01h 20m 13s} (1950)
GRB_DEC:          +5.842d {+05d 50' 31"} (J2000),
                  +5.897d {+05d 53' 51"} (current),
                  +5.581d {+05d 34' 52"} (1950)
GRB_DATE:        15431 TJD;   235 DOY;   10/08/23
GRB_TIME:        62735.71 SOD {17:25:35.71} UT
TRIGGER_INDEX:   137
GRB_PHI:         -174.59 [deg]
GRB_THETA:        23.97 [deg]
DELTA_TIME:      58.00 [sec]
TRIGGER_DUR:     1.024 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     15.84 [sigma]
IMAGE_SIGNIF:    10.50 [sigma]
LC_URL:          sw00432420000msb.lc
SUN_POSTN:       152.54d {+10h 10m 10s}  +11.30d {+11d 18' 12"}
SUN_DIST:        128.96 [deg]   Sun_angle= 8.8 [hr] (West of Sun)
MOON_POSTN:      321.18d {+21h 24m 42s}  -11.84d {-11d 50' 36"}
MOON_DIST:        61.93 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      137.05,-56.17 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       21.32, -2.67 [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 = 177.66,-17.59 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 23 Aug 10 17:29:51 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     432420,   Seg_Num: 0
POINT_RA:         20.700d {+01h 22m 48s} (J2000)
POINT_DEC:        +5.842d {+05d 50' 32"} (J2000)
POINT_ROLL:      70.242d
IMG_START_DATE:  15431 TJD;   235 DOY;   10/08/23
IMG_START_TIME:  62813.18 SOD {17:26:53.18} UT,   77.5 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.712
N_STARS:         17
X_OFFSET:        512 [pixels]
Y_OFFSET:        536 [pixels]
X_MAX:           1471 [pixels]
Y_MAX:           1495 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    7
SL_URL:          sw00432420000msufc0077.fits
SUN_POSTN:       152.54d {+10h 10m 11s}  +11.30d {+11d 18' 12"}
SUN_DIST:        128.96 [deg]   Sun_angle= 8.8 [hr] (West of Sun)
MOON_POSTN:      321.18d {+21h 24m 43s}  -11.84d {-11d 50' 32"}
MOON_DIST:        61.92 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      137.04,-56.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       21.32, -2.66 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 23 Aug 10 17:30:13 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     432420,   Seg_Num: 0
POINT_RA:         20.700d {+01h 22m 48s} (J2000)
POINT_DEC:        +5.842d {+05d 50' 32"} (J2000)
POINT_ROLL:      70.242d
IMG_START_DATE:  15431 TJD;   235 DOY;   10/08/23
IMG_START_TIME:  62813.18 SOD {17:26:53.18} UT,   77.5 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.712
N_STARS:         17
X_OFFSET:        512 [pixels]
Y_OFFSET:        536 [pixels]
X_MAX:           1471 [pixels]
Y_MAX:           1495 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    7
SL_URL:          sw00432420000msufc0077.fits
SUN_POSTN:       152.54d {+10h 10m 11s}  +11.30d {+11d 18' 12"}
SUN_DIST:        128.96 [deg]   Sun_angle= 8.8 [hr] (West of Sun)
MOON_POSTN:      321.18d {+21h 24m 44s}  -11.84d {-11d 50' 28"}
MOON_DIST:        61.92 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      137.04,-56.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       21.32, -2.66 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 23 Aug 10 17:31:23 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     432420,   Seg_Num: 0
POINT_RA:         20.700d {+01h 22m 48s} (J2000)
POINT_DEC:        +5.842d {+05d 50' 32"} (J2000)
ROLL:            70.242d
IMG_START_DATE:  15431 TJD;   235 DOY;   10/08/23
IMG_START_TIME:  62813.18 SOD {17:26:53.18} UT,   77.5 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     304277219
X_OFFSET:        835 [pixels]
Y_OFFSET:        924 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       995
Y_GRB_POS:       1084
BINNING_INDEX:   1
IM_URL:          sw00432420000msuni0084.fits
SUN_POSTN:       152.54d {+10h 10m 11s}  +11.30d {+11d 18' 11"}
SUN_DIST:        128.96 [deg]   Sun_angle= 8.8 [hr] (West of Sun)
MOON_POSTN:      321.19d {+21h 24m 46s}  -11.84d {-11d 50' 15"}
MOON_DIST:        61.91 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      137.04,-56.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       21.32, -2.66 [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:     Mon 23 Aug 10 17:31:40 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     432420,   Seg_Num: 0
POINT_RA:         20.700d {+01h 22m 48s} (J2000)
POINT_DEC:        +5.842d {+05d 50' 32"} (J2000)
ROLL:            70.242d
IMG_START_DATE:  15431 TJD;   235 DOY;   10/08/23
IMG_START_TIME:  62813.18 SOD {17:26:53.18} UT,   77.5 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     304277219
X_OFFSET:        835 [pixels]
Y_OFFSET:        924 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       995
Y_GRB_POS:       1084
BINNING_INDEX:   1
IM_URL:          sw00432420000msuni0084.fits
SUN_POSTN:       152.54d {+10h 10m 11s}  +11.30d {+11d 18' 10"}
SUN_DIST:        128.96 [deg]   Sun_angle= 8.8 [hr] (West of Sun)
MOON_POSTN:      321.19d {+21h 24m 46s}  -11.84d {-11d 50' 12"}
MOON_DIST:        61.91 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      137.04,-56.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       21.32, -2.66 [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 Circular #11135
V. Mangano (INAF-IASFPA), S. D. Barthelmy (GSFC), D. N. Burrows (PSU), M. M. Chester (PSU), N. Gehrels (NASA/GSFC), J. M. Gelbord (PSU), E. A. Hoversten (PSU), J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA), F. E. Marshall (NASA/GSFC), P. T. O'Brien (U Leicester), T. Sakamoto (NASA/UMBC), M. C. Stroh (PSU) and E. Troja (NASA/GSFC/ORAU) report on behalf of the Swift Team:
At 17:25:35 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 100823A (trigger=432420). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 20.703, +5.842, which is
```
   RA(J2000)  =  01h 22m 49s
   Dec(J2000) = +05d 50' 31"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single FRED-like peak with a duration of about 25 sec. The peak count rate was ~1000 counts/sec (15-350 keV), at ~2 sec after the trigger.
The XRT began observing the field at 17:26:44.6 UT, 68.9 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source located at RA, Dec 20.70383, 5.83361 which is equivalent to:
```
   RA(J2000)  = 01h 22m 48.92s
   Dec(J2000) = +05d 50' 01.0"
```
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This location is 30 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 in excess of the Galactic value (3.73e+20 cm^-2, Kalberla et al. 2005), with an excess column of 2.1 (+1.87/-1.66) x 10^21 cm^-2 (90% confidence).
The initial flux in the 2.5 s image was 5.93e-10 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 77 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 3-sigma upper limit is 19.3 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 0.04.
Burst Advocate for this burst is V. Mangano (vanessa AT ifc.inaf.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:     Mon 23 Aug 10 17:38:34 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     432420,   Seg_Num: 0
POINT_RA:         20.699d {+01h 22m 48s} (J2000)
POINT_DEC:        +5.839d {+05d 50' 22"} (J2000)
POINT_ROLL:      70.244d
IMG_START_DATE:  15431 TJD;   235 DOY;   10/08/23
IMG_START_TIME:  63025.41 SOD {17:30:25.41} UT,   289.7 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.221
N_STARS:         9
X_OFFSET:        515 [pixels]
Y_OFFSET:        604 [pixels]
X_MAX:           1474 [pixels]
Y_MAX:           1563 [pixels]
DET_THRESH:      9
PHOTO_THRESH:    4
SL_URL:          sw00432420000msufc0289.fits
SUN_POSTN:       152.55d {+10h 10m 12s}  +11.30d {+11d 18' 05"}
SUN_DIST:        128.97 [deg]   Sun_angle= 8.8 [hr] (West of Sun)
MOON_POSTN:      321.25d {+21h 24m 59s}  -11.82d {-11d 48' 55"}
MOON_DIST:        61.85 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      137.04,-56.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       21.31, -2.67 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 23 Aug 10 17:38:49 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     432420,   Seg_Num: 0
POINT_RA:         20.699d {+01h 22m 48s} (J2000)
POINT_DEC:        +5.839d {+05d 50' 22"} (J2000)
POINT_ROLL:      70.244d
IMG_START_DATE:  15431 TJD;   235 DOY;   10/08/23
IMG_START_TIME:  63025.41 SOD {17:30:25.41} UT,   289.7 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.221
N_STARS:         9
X_OFFSET:        515 [pixels]
Y_OFFSET:        604 [pixels]
X_MAX:           1474 [pixels]
Y_MAX:           1563 [pixels]
DET_THRESH:      9
PHOTO_THRESH:    4
SL_URL:          sw00432420000msufc0289.fits
SUN_POSTN:       152.55d {+10h 10m 12s}  +11.30d {+11d 18' 04"}
SUN_DIST:        128.97 [deg]   Sun_angle= 8.8 [hr] (West of Sun)
MOON_POSTN:      321.25d {+21h 25m 00s}  -11.81d {-11d 48' 52"}
MOON_DIST:        61.85 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      137.04,-56.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       21.31, -2.67 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 23 Aug 10 17:39:57 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     432420,   Seg_Num: 0
POINT_RA:         20.699d {+01h 22m 48s} (J2000)
POINT_DEC:        +5.839d {+05d 50' 22"} (J2000)
ROLL:            70.244d
IMG_START_DATE:  15431 TJD;   235 DOY;   10/08/23
IMG_START_TIME:  63025.41 SOD {17:30:25.41} UT,   289.7 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     304277431
X_OFFSET:        835 [pixels]
Y_OFFSET:        924 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       995
Y_GRB_POS:       1084
BINNING_INDEX:   1
IM_URL:          sw00432420000msuni0296.fits
SUN_POSTN:       152.55d {+10h 10m 12s}  +11.30d {+11d 18' 03"}
SUN_DIST:        128.97 [deg]   Sun_angle= 8.8 [hr] (West of Sun)
MOON_POSTN:      321.26d {+21h 25m 02s}  -11.81d {-11d 48' 39"}
MOON_DIST:        61.84 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      137.04,-56.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       21.31, -2.67 [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:     Mon 23 Aug 10 17:40:13 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     432420,   Seg_Num: 0
POINT_RA:         20.699d {+01h 22m 48s} (J2000)
POINT_DEC:        +5.839d {+05d 50' 22"} (J2000)
ROLL:            70.244d
IMG_START_DATE:  15431 TJD;   235 DOY;   10/08/23
IMG_START_TIME:  63025.41 SOD {17:30:25.41} UT,   289.7 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     304277431
X_OFFSET:        835 [pixels]
Y_OFFSET:        924 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       995
Y_GRB_POS:       1084
BINNING_INDEX:   1
IM_URL:          sw00432420000msuni0296.fits
SUN_POSTN:       152.55d {+10h 10m 12s}  +11.30d {+11d 18' 03"}
SUN_DIST:        128.97 [deg]   Sun_angle= 8.8 [hr] (West of Sun)
MOON_POSTN:      321.26d {+21h 25m 02s}  -11.81d {-11d 48' 36"}
MOON_DIST:        61.84 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      137.04,-56.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       21.31, -2.67 [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:     Mon 23 Aug 10 17:44:34 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     432420,   Seg_Num: 0
POINT_RA:         20.698d {+01h 22m 48s} (J2000)
POINT_DEC:        +5.840d {+05d 50' 23"} (J2000)
POINT_ROLL:      70.244d
IMG_START_DATE:  15431 TJD;   235 DOY;   10/08/23
IMG_START_TIME:  63601.89 SOD {17:40:01.89} UT,   866.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.503
N_STARS:         16
X_OFFSET:        275 [pixels]
Y_OFFSET:        364 [pixels]
X_MAX:           1714 [pixels]
Y_MAX:           1803 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00432420000msufc0866.fits
SUN_POSTN:       152.55d {+10h 10m 13s}  +11.30d {+11d 17' 59"}
SUN_DIST:        128.97 [deg]   Sun_angle= 8.8 [hr] (West of Sun)
MOON_POSTN:      321.29d {+21h 25m 10s}  -11.80d {-11d 47' 48"}
MOON_DIST:        61.80 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      137.04,-56.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       21.31, -2.67 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 23 Aug 10 17:44:51 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     432420,   Seg_Num: 0
POINT_RA:         20.698d {+01h 22m 48s} (J2000)
POINT_DEC:        +5.840d {+05d 50' 23"} (J2000)
POINT_ROLL:      70.244d
IMG_START_DATE:  15431 TJD;   235 DOY;   10/08/23
IMG_START_TIME:  63601.89 SOD {17:40:01.89} UT,   866.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.503
N_STARS:         16
X_OFFSET:        275 [pixels]
Y_OFFSET:        364 [pixels]
X_MAX:           1714 [pixels]
Y_MAX:           1803 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00432420000msufc0866.fits
SUN_POSTN:       152.55d {+10h 10m 13s}  +11.30d {+11d 17' 59"}
SUN_DIST:        128.97 [deg]   Sun_angle= 8.8 [hr] (West of Sun)
MOON_POSTN:      321.30d {+21h 25m 11s}  -11.80d {-11d 47' 45"}
MOON_DIST:        61.80 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      137.04,-56.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       21.31, -2.67 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        If you have elected to receive attachments:  
COMMENTS:        The uvot_catalog_srclist.fits.gz file does not exist; skipping the attachment.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 23 Aug 10 17:45:05 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     432420,   Seg_Num: 0
GRB_RA:           20.7043d {+01h 22m 49.03s} (J2000),
                  20.8428d {+01h 23m 22.27s} (current),
                  20.0541d {+01h 20m 12.98s} (1950)
GRB_DEC:          +5.8349d {+05d 50' 05.6"} (J2000),
                  +5.8903d {+05d 53' 25.0"} (current),
                  +5.5739d {+05d 34' 26.1"} (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:  15431 TJD;   235 DOY;   10/08/23
IMG_START_TIME:  62877.00 SOD {17:27:57.00} UT,   141.3 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       152.55d {+10h 10m 13s}  +11.30d {+11d 17' 59"}
SUN_DIST:        128.97 [deg]   Sun_angle= 8.8 [hr] (West of Sun)
MOON_POSTN:      321.30d {+21h 25m 11s}  -11.80d {-11d 47' 42"}
MOON_DIST:        61.80 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      137.05,-56.17 [deg] galactic lon,lat of the burst
ECL_COORDS:       21.32, -2.67 [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:     Mon 23 Aug 10 17:45:51 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     432420,   Seg_Num: 0
POINT_RA:         20.698d {+01h 22m 48s} (J2000)
POINT_DEC:        +5.840d {+05d 50' 23"} (J2000)
ROLL:            70.244d
IMG_START_DATE:  15431 TJD;   235 DOY;   10/08/23
IMG_START_TIME:  63601.89 SOD {17:40:01.89} UT,   866.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     304278008
X_OFFSET:        834 [pixels]
Y_OFFSET:        923 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       994
Y_GRB_POS:       1083
BINNING_INDEX:   1
IM_URL:          sw00432420000msuni0873.fits
SUN_POSTN:       152.55d {+10h 10m 13s}  +11.30d {+11d 17' 58"}
SUN_DIST:        128.97 [deg]   Sun_angle= 8.8 [hr] (West of Sun)
MOON_POSTN:      321.30d {+21h 25m 13s}  -11.79d {-11d 47' 34"}
MOON_DIST:        61.79 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      137.04,-56.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       21.31, -2.67 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 23 Aug 10 17:46:08 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     432420,   Seg_Num: 0
POINT_RA:         20.698d {+01h 22m 48s} (J2000)
POINT_DEC:        +5.840d {+05d 50' 23"} (J2000)
ROLL:            70.244d
IMG_START_DATE:  15431 TJD;   235 DOY;   10/08/23
IMG_START_TIME:  63601.89 SOD {17:40:01.89} UT,   866.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     304278008
X_OFFSET:        834 [pixels]
Y_OFFSET:        923 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       994
Y_GRB_POS:       1083
BINNING_INDEX:   1
IM_URL:          sw00432420000msuni0873.fits
SUN_POSTN:       152.55d {+10h 10m 13s}  +11.30d {+11d 17' 58"}
SUN_DIST:        128.97 [deg]   Sun_angle= 8.8 [hr] (West of Sun)
MOON_POSTN:      321.31d {+21h 25m 13s}  -11.79d {-11d 47' 30"}
MOON_DIST:        61.79 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      137.04,-56.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       21.31, -2.67 [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:        If you have elected to receive attachments:  
COMMENTS:        The uvot_catalog_image.fits.gz file does not exist; skipping the attachment.

GCN Circular #11136
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team.
Using 251 s of XRT Photon Counting mode data and 1 UVOT images for GRB 100823A, 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 = 20.70428, +5.83510 which is equivalent to:
```
RA (J2000): 01h 22m 49.03s
Dec (J2000): +05d 50' 06.4"
```
with an uncertainty of 2.1 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 #11137
D. M. Palmer (LANL), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), V. Mangano (INAF-IASFPA), C. B. Markwardt (GSFC/UMD), T. Sakamoto (GSFC/UMBC), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+962 sec from recent telemetry downlinks, we report further analysis of BAT GRB 100823A (trigger #432420) (Mangano, et al., GCN Circ. 11135). The BAT ground-calculated position is RA, Dec = 20.706, 5.848 deg, which is
```
   RA(J2000)  =  01h 22m 49.4s 
   Dec(J2000) = +05d 50' 52.6" 
```
with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 92%.
The mask-weighted light curve shows a single FRED peak starting at ~T-2 sec, peaking at ~T+1 sec, and ending at T+150 sec. T90 (15-350 keV) is 16.9 +- 3.5 sec (estimated error including systematics).
The time-averaged spectrum from T-1.2 to T+18.2 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.19 +- 0.18. The fluence in the 15-150 keV band is 4.1 +- 0.4 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+0.14 sec in the 15-150 keV band is 1.0 +- 0.1 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/432420/BA/
GCN Circular #11138
A.J. Levan (U. Warwick), N.R. Tanvir (U. Leicester), C. Copperwheat (U. Warwick) report for a larger collaboration:
We observed the field of GRB 100823A (Mangano et al. GCN 11135) using the William Herschel Telescope on La Palma with the ACAM instrument. Observations were conducted in the z-band, and began at 00:37 UT, approximately 7.2 hours after the burst.
Within the refined X-ray error circle (Goad et al. GCN 11136) we identify a source, at
```
A:
RA(J2000): 01:22:48.97
DEC(J2000) 05:50:08.1
```
However, we note that a source is also present in the DSS2 images of the field at this position.
Additionally we note the presence of a brighter source, not present in the DSS images at
```
B:
RA(J2000): 01:22:48.79
DEC(J2000) 05:50:10.9
```
This source may be the afterglow of GRB 100823A (offset approximately ~6 arcseconds from the XRT position), or alternatively could either be a red source, not visible in the DSS2 red image, or a source with high proper motion.
Further observations will be required to assess the nature of any variability.
Images can be found at
http://www.star.le.ac.uk/~anl/100823A
and is reproduced below:

A image of the field of GRB 100823A observed with the WHT (left) and an archival DSS image (right). The XRT error circle is marked. As can be seen our observations reveal an object within the XRT error circle which is also visibile in the DSS (object A). Additionally, we find a further object (object B, indicated by the line) which is brighter than object A, but not visible in the DSS. At present we cannot distinguish between a colour term and a new source. Images are North up, and approximately 1.5 arcmin on a side.
GCN Circular #11139
M.M. Chester (PSU) and V. Mangano (INAF-IASFPA) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 100823A 78 s after the BAT trigger (Mangano et al., GCN Circ. 11135). No optical afterglow consistent with the enhanced Swift/XRT position (Goad et al., GCN Circ. 11136) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627) for the white and u finding chart (FC) and subsequent exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC            78          227          147         >20.1
u_FC               290          539          246         >19.4
white               78        17439         2181         >21.9
v                  619        22361         1331         >20.5
b                  545        16528         1278         >21.3
u                  290         6512          639         >20.4
w1                 669         6307          432         >20.2
m2                 816         6102          413         >20.8
w2                 767        18242         2082         >21.2
```
The values quoted above are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.04 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #11140
S. Guziy, A. Sota, J. Gorosabel and A.J. Castro-Tirado (IAA-CSIC Granada), on behalf of a larger collaboration, report:
"We have carried out I-band observations of the Swift GRB 100823A Mangano et al., GCNC 11135) error circle with the 1.5m telescope at Observatorio de Sierra Nevada, Spain. The data were acquired on Aug 24.1333-24.1890 UT with a total exposure time of 15x300s. The two objects reported by Levan et al. (GCNC 11138) are clearly detected with preliminary magnitudes of I = 20.8 for the one within the XRT error box and 20.4 for the one reported by Levan et al. using as photometric reference the USNO-B1.0 star located at RA(J2000) = 01:22:45.502, DEC(J2000) = +05:49:03.02. At the present stage we can not confirm variability in any of the two sources. Further observations are planned."
GCN Circular #11141
P. D'Avanzo (INAF-OAB), A.J. Levan (U. Warwick), D. Malesani (DARK/NBI), N.R. Tanvir (U. Leicester), E. Palazzi (INAF-IASFBo), A. Fiorenzano (INAF-TNG), report:
We observed the field of GRB 100823A (Mangano et al. GCN 11135) using the Italian 3.6m TNG telescope, located in the Canary Islands. A set of J-band images were acquired on Aug 24.03490 UT (~7.4 hours after the burst; mid exposure time) for a total exposure time of 16 minutes.
We detect the two objects reported by Levan et al. (GCN 11138) and Guziy et al. (GCN 11140) with magnitudes J=21.0 for object "A" (the one within the refined XRT error circle; Goad et al. GCN 11136) and J=19.4 for object "B", calibrated against the 2MASS catalogue.
Although we have yet to photometrically calibrate the z-band image, from a comparison of the TNG and WHT images (Levan et al. GCN 11138) we note that object "B" has a z-J color significantly redder with respect to the average color of field stars.
As suggested by Levan et al (GCN 11138) object "B" can thus be a red source not visible in the DSS2 red image. In light of this, its location outside the XRT refined error circle would make it likely unrelated to the GRB.
GCN Circular #11142
A.J. Levan (U. Warwick), N.R. Tanvir (U. Leicester), C. Copperwheat (U. Warwick) report for a larger collaboration:
We obtained a second epoch of observations of GRB 100823A (Mangano et al. GCN 11135) with the WHT, beginning at 05:38 UT, approximately 5 hours after our first epoch of observations (Levan et al. GCN 11138), and 12 hours after the GRB. In our images we detect both sources A and B, both of which are constant within the photometric errors.
Additionally, we have inspected archival images of the field obtained with the UKIRT Wide Field Camera (WFCAM) in November 2008 in the YJHK bands. Object B is faintly detected in all bands, while object A is below the detection limit of the shallow observations.
Given the location of object B well outside the refined XRT error circle (Goad et al. GCN 11136) these results imply that it is not related to GRB 100823A, confirming the conclusion of D'Avanzo et al. (GCN 11141). We cannot rule out a faint contribution of afterglow to object A, but it non-variability in our observations, coupled with its detection in DSS2 suggest that it is not afterglow dominated."
GCN Circular #11143
P. D'Avanzo (INAF/Brera), P. Jakobsson (Reykjavik), H. Flores (Paris Obs.), P. Goldoni (APC/Univ. Paris 7 and SAp/CEA), N. R. Tanvir, K. Wiersema (U. Leicester), A. J. Levan (U. Warwick), D. Malesani, J. P. U. Fynbo, and B. Milvang-Jensen (DARK), report on behalf of a larger collaboration:
We observed the location of GRB 100823A (Mangano et al. GCN 11135) with the ESO VLT equipped with the X-shooter spectrograph on 2010 Aug 24, beginning 08:17 UT (15.5 hr after the GRB). The slit was aligned so to include both objects A and B first mentioned by Levan et al. (GCN 11138; see also Guziy et al., GCN 11140; D'Avanzo et al., GCN 11141). We detect both objects in the acquisition image, and confirm that object B is fainter than the DSS limit.
In the spectra, we detect continuum from source A, and identify its spectrum as being that of an M-dwarf based on evident TiO bands. Given that object B is also likely unrelated to the GRB (D'Avanzo et al., GCN 11141; Levan et al., GCN 11142), we conclude that either the GRB event is itself associated with a flare from this star, or that the GRB afterglow is a fainter source not reported so far.
We acknowledge the support of the VLT staff, in particular Claudia Cid, Stephane Brillant, Jonathan Smoker, and Christophe Martayan.
GCN Circular #11144
V. Mangano (INAF IASF-PA) and B. Sbarufatti (INAF OAB/INAF IASF-PA) report on behalf of the Swift-XRT team:
We have analyzed 8.7 ks of XRT data for GRB 100823A (Mangano et al. GCN Circ. 11135), from 59 s to 22 ks after the BAT trigger. The data comprise 68 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 light curve can be modeled with a broken power-law decay with an initial decay index of alpha1=2.9 (+/-0.2) , a break at T+163 (+/-11) s and a final decay index of alpha2=1.19 (+/-0.03).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 3.6 (+0.8, -0.6). The best-fitting absorption column is 2.8 (+1.2, -0.9) x 10^21 cm^-2, in excess of the Galactic value of 3.7 x 10^20 cm^-2 (Kalberla et al. 2005). The PC mode spectrum (extracted from T+137.5 s to T+22.3 ks, 8.65 ks exposure) has a photon index of 2.2 (+0.3, -0.2) and a best-fitting absorption column of 2.1 (+0.6, -0.5) 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 (6.6 x 10^-11) erg cm^-2 count^-1.
If the light curve continues to decay with a power-law decay index of 0.87, the count rate at T+48 hours will be 9.0 x 10^-4 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.6 x 10-14 (5.9 x 10^-14) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00432420.
This circular is an official product of the Swift-XRT team.
GCN Circular #11145
A.J. Levan (U. Warwick), K. Wiersema, N. Tanvir (U. Leicester), C. Copperwheat (U. Warwick) report on behalf of a larger collaboration:
We obtained infrared imaging of the location of GRB 100823A ( using LIRIS on the 4.2m WHT, beginning at 01:34 UT, ~8 hours after the burst. Observations were obtained in the JH and K bands, with a total exposure time of 540 s in each band.
We detect sources A and B of Levan et al. (GCN), but also find a new source within the XRT error circle of Goad et al. GCN 11135, but see also, http://www.swift.ac.uk/xrt_positions/00432420/image.php with a position of,
```
C: 
RA(J2000) 01:22:48.94 
DEC(J2000) 05:50:05.9
```
The object has K=19.6 calibrated against 2MASS, and is faintly visible in the H-band, but not in the J or z, suggestive of a red colour. At the current time we cannot make statements as to the variability of the source, but its red colour, akin to extinguished GRB afterglows, coupled with a location within the XRT error circle leads us to suggest that it is the afterglow of GRB 100823A.
GCN Circular #11146
D. Suzuki, K. Omori, N. Miyake, S. Kobara, H. Naito and T. Sako (STE Lab, Nagoya Univ.), T. Saito (Tokyo Metropolitan College of Industrial Technology) and K. Wada (Konan Univ.) on behalf of the MOA Collaboration report:
We searched for an optical afterglow of GRB 100823A (GCN 11135, Mangano et al.) starting from 17:30:34 UT on 2010 Aug 23 (5 minutes after the burst) with the MOA-II 1.8m telescope at Mt.John observatory in New Zealand. In a single image of a 60sec exposure with a wideband Red filter (center wavelength ~ 750nm and FWHM ~ 250nm), we found an object not found in the USNO-B1.0 catalog within the error circle of the Swift XRT source position (GCN 11136 Goad et al.). The position coincides with the source C (GCN 11145, Levan et al.) and the magnitude is estimated to be I=17.1mag.
Additionally, we obtained a second epoch of observation of GRB 100823A starting from 14:59:16 UT on 2010 Aug 24 (approximately 21.5 hours after the burst). In a single image of a 300sec exposure with a wideband Red filter, we detected source A (GCN 11138, Levan et al.) with magnitude I=21.3mag ,but we did not detect the source C in this epoch.
This photometry were done by using the DoPhot and calibrated against the USNO-B1.0 catalog stars, and not corrected for the Galactic extinction.
GCN Circular #11148
M. M. Chester (PSU), T.S. Koch (PSU), E. A. Hoversten (PSU), and V. Mangano (INAF-IASFPA) report on behalf of the Swift/UVOT team:
Further examination of Swift/UVOT observations of GRB 100823A show that a source detected in the white finding chart exposure, initially thought to correspond to the DSS2 source mentioned in Levan et al., GCN Circ. 11138, faded in subsequent exposures to an apparently steady level. The source was marginally detected in the u finding chart exposure. The position of the source in both the finding chart and later images is consistent with the enhanced XRT position (Goad et al., GCN Circ. 11136). We propose this result as further evidence that Source C in Levan et al., GCN Circ. 11145, and referenced in Suzuki et al., GCN Circ. 11146, is the afterglow of GRB 100823A.
Magnitudes for the white and u finding charts and white optimally co- added exposures are given in the following table. All photometry was performed using the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627). The values quoted are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.04 in the direction of the burst (Schlegel et al. 1998).
```
Filter    T_start(s)     T_stop(s)     Exp(s)     Mag    Error     S/N
white_FC     78            227           147      20.7   +/-0.3    2.9
u_FC        290            539           246      20.4   +/-0.4    2.1
white       576          57266          3157      23.4   +/-0.8    2.3
white     61907          63386          1453      22.9   +/-0.7    2.4
white     67668          73670          2674      23.3   +/-0.8    2.1
white     73673          75876          2168      23.0   +/-0.7    2.5
```
The UVOT position determined from co-adding all of the later images (after T=56215s) is:
```
     RA (J2000)  01:22:49.03  =  20.70429 (deg)
    Dec (J2000) +05:50:06.4   =  +5.83511 (deg)
```
with an estimated uncertainty of 0.9 arcsec (radius, 90% confidence, statistical + systematic).
GCN Circular #11151
M. Serino, T. Mihara, Y.E. Nakagawa, M. Sugizaki, T. Yamamoto, T. Sootome, M. Matsuoka (RIKEN), N. Kawai, M. Morii, K. Sugimori, R. Usui (Tokyo Tech), K. Kawasaki, S. Ueno, H. Tomida, M. Kohama, M. Ishikawa (JAXA), A. Yoshida, K. Yamaoka, S. Nakahira (AGU), H. Tsunemi, M. Kimura (Osaka U.), H. Negoro, M. Nakajima H. Ozawa, F. Suwa (Nihon U.), Y. Ueda, N. Isobe, S. Eguchi, K. Hiroi (Kyoto U.), A. Daikyuji (Miyazaki U.), A. Uzawa, T. Matsumura, K. Yamazaki (Chuo U.) report on behalf of the MAXI team:
The Gas Slit Camera (GSC) of MAXI detected a bright X-ray source at the position consistent with GRB 100823A (Mangano et al, GCN 11135). Assuming the XRT position (Goad et al., GCN 11136), the transit of GSC over the source started at 17:25:25 UT on 23 August 2010, 10 seconds before the Swift/BAT trigger time. A significant (8 sigma in 2-20 keV) rise of the count rate above the background was observed at 17:25:33, and the burst was detected significantly for 25 seconds. The peak X-ray flux (4-10 keV) was about 2.5 Crab, which was corrected for the collimator transmission efficiency assuming the source position by Swift XRT. There are significant time structure within the transit light curve, which would be simply triangular for a steady source. From the preliminary spectral analysis, the time-averaged spectrum from T+0 to T+25 sec is best fit by a power-law model with a photon index of 2.0 +/- 0.2. The fluence in the 2-20 keV band is 5.1 +0.5 -0.9 x 10^-7 erg/cm2.
The sky image and the transit light curve is shown at the MAXI web site http://maxi.riken.jp/ in the "News" section.
GCN Circular #11152
A. Pozanenko (IKI), A. Volnova (SAI MSU), B. Satovski (Astrotel), M. Ibrahimov (MAO) report on behalf of larger GRB follow-up collaboration:
We observed the field of the Swift GRB 100823A (Mangano et al. GCN 11135) with AZT-22 telescope of Maidanak observatory. Several images in I-filter were obtained starting on Aug. 23 (UT) 20:47:02.
We do not detect the object C (Levan et al. GCN 11145; Suzuki et al. GCN 11146) up to I=22.2m. We clearly detect both objects A and B (Levan et al. GCN 11138). The photometry of stacked image is based on USNO-B1.0 star 0958-0013520 located at RA(J2000) = 01:22:45.50, DEC(J2000) = +05:49:03.0 and used as reference star in GCN 11140 (Guziy et al).
```
Object,   t-T0,       Filter,   Exposure,    OT,                  Upper 
limit (3 sigma)
              (mid, d)               (s)
A           0.16605   I        19*180        21.06+/-0.09           22.2
B           0.16605   I        19*180        20.60+/-0.06           22.2
```
The photometry of the object A is compatible with photometry reported in GCN 11146 (Suzuki et al). Using photometry of the object C starting 5 minutes after burst (Suzuki et al. GCN 11146) and upper limit I=22.2m at 0.16605 days one can estimate power law decay index alpha > 1.25.
We thank Otabek Burhonov for performing the observations and for his support.
GCN Circular #11154
K. Antoniuk, V. Rumyantsev (CrAO), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:
We observed the field of the Swift GRB 100823A (Mangano et al. GCN 11135) with AZT-11 telescope of CrAO observatory. Several images in R-filter were obtained on Aug. 23 between (UT) 22:05 - 22:53.
In enhanced XRT position (Goad et al. GCN 11136) we do not detect any source up to R=20.7. The photometry of stacked image is based on USNO-B1.0 star 0958-0013520 located at RA(J2000) = 01:22:45.50, DEC(J2000) = +05:49:03.0 (assuming R=16.75):
```
 t-T0,       Filter,   Exposure,    OT,       Upper limit (3 sigma)
(mid, d)               (s)
 0.2111   R         15*180         n/d           20.7
```
GCN Report 297.1
GCN_Report 297.1 has been posted: http://gcn.gsfc.nasa.gov/reports/report_297_1.pdf by V. Mangano at INAF/IASF_Pa titled: "Final report on Swift Observations of GRB 100823A"

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Jochen Greiner, last update: 23-Aug-2010 [Disclaimer]