Gamma-ray Burst 120923A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

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Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 23 Sep 12 05:17:38 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     534402,   Seg_Num: 0
GRB_RA:          303.795d {+20h 15m 11s} (J2000),
                 303.952d {+20h 15m 48s} (current),
                 303.180d {+20h 12m 43s} (1950)
GRB_DEC:          +6.235d {+06d 14' 05"} (J2000),
                  +6.274d {+06d 16' 27"} (current),
                  +6.081d {+06d 04' 52"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       117679 [cnts]    Image_Peak=1290 [image_cnts]
TRIGGER_DUR:     26.880 [sec] 
TRIGGER_INDEX:   463     E_range: 15-50 keV
BKG_INTEN:       268230 [cnts]
BKG_TIME:        18854.31 SOD {05:14:14.31} UT
BKG_DUR:         64 [sec]
GRB_DATE:        16193 TJD;   267 DOY;   12/09/23
GRB_TIME:        18966.25 SOD {05:16:06.25} UT
GRB_PHI:          64.33 [deg]
GRB_THETA:        16.96 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     10.67 [sigma]
IMAGE_SIGNIF:    8.88 [sigma]
MERIT_PARAMS:     +1  +0  +0  +5  +1  -1  +0  +0 +54  +0 
SUN_POSTN:       180.54d {+12h 02m 09s}   -0.23d {-00d 13' 56"}
SUN_DIST:        123.22 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      276.22d {+18h 24m 53s}  -20.20d {-20d 11' 48"}
MOON_DIST:        38.00 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:       48.50,-15.46 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      307.73, 25.36 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Coordinates.  
COMMENTS:        This Notice was delayed by more than 60 sec past the end of the trigger integration interval;  
COMMENTS:        probably due to it occurring during a Malindi downlink session.  
COMMENTS:        This is a rate trigger.  
COMMENTS:        A point_source was found.  
COMMENTS:        This does not match any source in the on-board catalog.  
COMMENTS:        This does not match any source in the ground catalog.  
COMMENTS:        This is a GRB.  
COMMENTS:        This trigger occurred at longitude,latitude = 187.48,0.72 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 23 Sep 12 05:18:41 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     534402,   Seg_Num: 0
POINT_RA:        303.773d {+20h 15m 06s} (J2000)
POINT_DEC:        +6.232d {+06d 13' 57"} (J2000)
IMG_START_DATE:  16193 TJD;   267 DOY;   12/09/23
IMG_START_TIME:  19106.00 SOD {05:18:26.00} UT,   139.8 [sec] since BAT Trigger Time
COUNTS:          2    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:     Sun 23 Sep 12 05:20:23 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     534402,   Seg_Num: 0
GRB_RA:          303.795d {+20h 15m 11s} (J2000),
                 303.952d {+20h 15m 48s} (current),
                 303.180d {+20h 12m 43s} (1950)
GRB_DEC:          +6.235d {+06d 14' 05"} (J2000),
                  +6.274d {+06d 16' 27"} (current),
                  +6.081d {+06d 04' 52"} (1950)
GRB_DATE:        16193 TJD;   267 DOY;   12/09/23
GRB_TIME:        18966.25 SOD {05:16:06.25} UT
TRIGGER_INDEX:   463
GRB_PHI:          64.33 [deg]
GRB_THETA:        16.96 [deg]
DELTA_TIME:      7.00 [sec]
TRIGGER_DUR:     26.880 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     10.67 [sigma]
IMAGE_SIGNIF:    8.88 [sigma]
LC_URL:          sw00534402000msb.lc
SUN_POSTN:       180.54d {+12h 02m 09s}   -0.23d {-00d 14' 00"}
SUN_DIST:        123.22 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      276.25d {+18h 25m 00s}  -20.19d {-20d 11' 36"}
MOON_DIST:        37.98 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:       48.50,-15.46 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      307.73, 25.36 [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 = 187.48,0.72 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 23 Sep 12 05:21:36 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     534402,   Seg_Num: 0
POINT_RA:        303.773d {+20h 15m 05s} (J2000)
POINT_DEC:        +6.232d {+06d 13' 57"} (J2000)
POINT_ROLL:      273.796d
IMG_START_DATE:  16193 TJD;   267 DOY;   12/09/23
IMG_START_TIME:  19109.45 SOD {05:18:29.45} UT,   143.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.514
N_STARS:         190
X_OFFSET:        342 [pixels]
Y_OFFSET:        667 [pixels]
X_MAX:           1301 [pixels]
Y_MAX:           1626 [pixels]
DET_THRESH:      13
PHOTO_THRESH:    7
SL_URL:          sw00534402000msufc0143.fits
SUN_POSTN:       180.54d {+12h 02m 09s}   -0.23d {-00d 14' 00"}
SUN_DIST:        123.19 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      276.26d {+18h 25m 03s}  -20.19d {-20d 11' 31"}
MOON_DIST:        37.95 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:       48.48,-15.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      307.70, 25.36 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 23 Sep 12 05:22:13 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     534402,   Seg_Num: 0
POINT_RA:        303.773d {+20h 15m 05s} (J2000)
POINT_DEC:        +6.232d {+06d 13' 57"} (J2000)
POINT_ROLL:      273.796d
IMG_START_DATE:  16193 TJD;   267 DOY;   12/09/23
IMG_START_TIME:  19109.45 SOD {05:18:29.45} UT,   143.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.514
N_STARS:         190
X_OFFSET:        342 [pixels]
Y_OFFSET:        667 [pixels]
X_MAX:           1301 [pixels]
Y_MAX:           1626 [pixels]
DET_THRESH:      13
PHOTO_THRESH:    7
SL_URL:          sw00534402000msufc0143.fits
SUN_POSTN:       180.54d {+12h 02m 09s}   -0.23d {-00d 14' 01"}
SUN_DIST:        123.19 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      276.27d {+18h 25m 05s}  -20.19d {-20d 11' 29"}
MOON_DIST:        37.94 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:       48.48,-15.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      307.70, 25.36 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 23 Sep 12 05:23:07 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     534402,   Seg_Num: 0
POINT_RA:        303.773d {+20h 15m 05s} (J2000)
POINT_DEC:        +6.232d {+06d 13' 57"} (J2000)
ROLL:            273.796d
IMG_START_DATE:  16193 TJD;   267 DOY;   12/09/23
IMG_START_TIME:  19109.45 SOD {05:18:29.45} UT,   143.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     370070319
X_OFFSET:        661 [pixels]
Y_OFFSET:        986 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       821
Y_GRB_POS:       1146
BINNING_INDEX:   1
IM_URL:          sw00534402000msuni0153.fits
SUN_POSTN:       180.54d {+12h 02m 10s}   -0.23d {-00d 14' 02"}
SUN_DIST:        123.19 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      276.28d {+18h 25m 07s}  -20.19d {-20d 11' 25"}
MOON_DIST:        37.94 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:       48.48,-15.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      307.70, 25.36 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 23 Sep 12 05:23:19 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     534402,   Seg_Num: 0
POINT_RA:        303.773d {+20h 15m 05s} (J2000)
POINT_DEC:        +6.232d {+06d 13' 57"} (J2000)
ROLL:            273.796d
IMG_START_DATE:  16193 TJD;   267 DOY;   12/09/23
IMG_START_TIME:  19109.45 SOD {05:18:29.45} UT,   143.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     370070319
X_OFFSET:        661 [pixels]
Y_OFFSET:        986 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       821
Y_GRB_POS:       1146
BINNING_INDEX:   1
IM_URL:          sw00534402000msuni0153.fits
SUN_POSTN:       180.54d {+12h 02m 10s}   -0.23d {-00d 14' 02"}
SUN_DIST:        123.19 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      276.28d {+18h 25m 07s}  -20.19d {-20d 11' 24"}
MOON_DIST:        37.94 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:       48.48,-15.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      307.70, 25.36 [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:     Sun 23 Sep 12 05:23:37 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     534402,   Seg_Num: 0
GRB_RA:          303.7963d {+20h 15m 11.11s} (J2000),
                 303.9529d {+20h 15m 48.70s} (current),
                 303.1808d {+20h 12m 43.38s} (1950)
GRB_DEC:          +6.2203d {+06d 13' 13.0"} (J2000),
                  +6.2598d {+06d 15' 35.2"} (current),
                  +6.0667d {+06d 04' 00.0"} (1950)
GRB_ERROR:       4.1 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  16193 TJD;   267 DOY;   12/09/23
IMG_START_TIME:  19137.00 SOD {05:18:57.00} UT,   170.8 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       180.54d {+12h 02m 10s}   -0.23d {-00d 14' 02"}
SUN_DIST:        123.22 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      276.28d {+18h 25m 08s}  -20.19d {-20d 11' 23"}
MOON_DIST:        37.94 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:       48.48,-15.47 [deg] galactic lon,lat of the burst
ECL_COORDS:      307.72, 25.34 [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 0.58% < P(seren) < 1.1%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 23 Sep 12 05:28:07 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     534402,   Seg_Num: 0
POINT_RA:        303.771d {+20h 15m 05s} (J2000)
POINT_DEC:        +6.232d {+06d 13' 54"} (J2000)
POINT_ROLL:      273.797d
IMG_START_DATE:  16193 TJD;   267 DOY;   12/09/23
IMG_START_TIME:  19267.45 SOD {05:21:07.45} UT,   301.2 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.692
N_STARS:         190
X_OFFSET:        102 [pixels]
Y_OFFSET:        427 [pixels]
X_MAX:           1541 [pixels]
Y_MAX:           1866 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw00534402000msufc0301.fits
SUN_POSTN:       180.54d {+12h 02m 10s}   -0.24d {-00d 14' 07"}
SUN_DIST:        123.19 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      276.33d {+18h 25m 19s}  -20.18d {-20d 11' 05"}
MOON_DIST:        37.90 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:       48.48,-15.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      307.70, 25.36 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 23 Sep 12 05:28:39 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     534402,   Seg_Num: 0
POINT_RA:        303.771d {+20h 15m 05s} (J2000)
POINT_DEC:        +6.232d {+06d 13' 54"} (J2000)
POINT_ROLL:      273.797d
IMG_START_DATE:  16193 TJD;   267 DOY;   12/09/23
IMG_START_TIME:  19267.45 SOD {05:21:07.45} UT,   301.2 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.692
N_STARS:         190
X_OFFSET:        102 [pixels]
Y_OFFSET:        427 [pixels]
X_MAX:           1541 [pixels]
Y_MAX:           1866 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw00534402000msufc0301.fits
SUN_POSTN:       180.54d {+12h 02m 10s}   -0.24d {-00d 14' 07"}
SUN_DIST:        123.19 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      276.34d {+18h 25m 21s}  -20.18d {-20d 11' 03"}
MOON_DIST:        37.89 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:       48.48,-15.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      307.70, 25.36 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 23 Sep 12 05:28:44 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     534402,   Seg_Num: 0
GRB_RA:          303.7950d {+20h 15m 10.80s} (J2000),
                 303.9516d {+20h 15m 48.39s} (current),
                 303.1795d {+20h 12m 43.07s} (1950)
GRB_DEC:          +6.2207d {+06d 13' 14.5"} (J2000),
                  +6.2602d {+06d 15' 36.6"} (current),
                  +6.0671d {+06d 04' 01.5"} (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:  16193 TJD;   267 DOY;   12/09/23
IMG_START_TIME:  19137.00 SOD {05:18:57.00} UT,   170.8 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       180.54d {+12h 02m 10s}   -0.24d {-00d 14' 07"}
SUN_DIST:        123.21 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      276.34d {+18h 25m 21s}  -20.18d {-20d 11' 02"}
MOON_DIST:        37.90 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:       48.48,-15.47 [deg] galactic lon,lat of the burst
ECL_COORDS:      307.72, 25.34 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        This is an Update Notice -- the RA,Dec values herein supersede the previous XRT_POS Notice.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        This position was enhanced using UVOT field astrometry.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.58% < P(seren) < 1.1%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 23 Sep 12 05:29:53 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     534402,   Seg_Num: 0
POINT_RA:        303.771d {+20h 15m 05s} (J2000)
POINT_DEC:        +6.232d {+06d 13' 54"} (J2000)
ROLL:            273.797d
IMG_START_DATE:  16193 TJD;   267 DOY;   12/09/23
IMG_START_TIME:  19267.45 SOD {05:21:07.45} UT,   301.2 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     370070477
X_OFFSET:        661 [pixels]
Y_OFFSET:        986 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       821
Y_GRB_POS:       1146
BINNING_INDEX:   1
IM_URL:          sw00534402000msuni0311.fits
SUN_POSTN:       180.54d {+12h 02m 11s}   -0.24d {-00d 14' 08"}
SUN_DIST:        123.19 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      276.35d {+18h 25m 24s}  -20.18d {-20d 10' 58"}
MOON_DIST:        37.88 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:       48.48,-15.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      307.70, 25.36 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 23 Sep 12 05:30:03 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     534402,   Seg_Num: 0
POINT_RA:        303.771d {+20h 15m 05s} (J2000)
POINT_DEC:        +6.232d {+06d 13' 54"} (J2000)
ROLL:            273.797d
IMG_START_DATE:  16193 TJD;   267 DOY;   12/09/23
IMG_START_TIME:  19267.45 SOD {05:21:07.45} UT,   301.2 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     370070477
X_OFFSET:        661 [pixels]
Y_OFFSET:        986 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       821
Y_GRB_POS:       1146
BINNING_INDEX:   1
IM_URL:          sw00534402000msuni0311.fits
SUN_POSTN:       180.54d {+12h 02m 11s}   -0.24d {-00d 14' 08"}
SUN_DIST:        123.19 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      276.35d {+18h 25m 24s}  -20.18d {-20d 10' 57"}
MOON_DIST:        37.88 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:       48.48,-15.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      307.70, 25.36 [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 #13796
V. N. Yershov (UCL-MSSL), S. D. Barthelmy (GSFC), H. A. Krimm (CRESST/GSFC/USRA), N. P. M. Kuin (UCL-MSSL), C. J. Mountford (U Leicester), S. R. Oates (UCL-MSSL), K. L. Page (U Leicester) and M. H. Siegel (PSU) report on behalf of the Swift Team:
At 05:16:06 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 120923A (trigger=534402). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 303.795, +6.235 which is
```
   RA(J2000)  =  20h 15m 11s
   Dec(J2000) = +06d 14' 05"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows several overlapping peaks with a total duration of about 35 sec. The peak count rate was ~700 counts/sec (15-350 keV), at ~6 sec after the trigger.
The XRT began observing the field at 05:18:26.0 UT, 139.8 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 303.79631, 6.22039 which is equivalent to:
```
   RA(J2000)  = 20h 15m 11.11s
   Dec(J2000) = +06d 13' 13.4"
```
with an uncertainty of 4.1 arcseconds (radius, 90% containment). This location is 52 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. We cannot determine whether the source is fading at the present time.
A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 9.80 x 10^20 cm^-2 (Kalberla et al. 2005).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 143 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 0.16.
Burst Advocate for this burst is V. N. Yershov (vny AT mssl.ucl.ac.uk). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.)

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 23 Sep 12 05:33:20 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     534402,   Seg_Num: 0
POINT_RA:        303.771d {+20h 15m 05s} (J2000)
POINT_DEC:        +6.231d {+06d 13' 53"} (J2000)
POINT_ROLL:      273.797d
IMG_START_DATE:  16193 TJD;   267 DOY;   12/09/23
IMG_START_TIME:  19825.94 SOD {05:30:25.94} UT,   859.7 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.412
N_STARS:         190
X_OFFSET:        102 [pixels]
Y_OFFSET:        427 [pixels]
X_MAX:           1541 [pixels]
Y_MAX:           1866 [pixels]
DET_THRESH:      13
PHOTO_THRESH:    7
SL_URL:          sw00534402000msufc0859.fits
SUN_POSTN:       180.55d {+12h 02m 11s}   -0.24d {-00d 14' 12"}
SUN_DIST:        123.19 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      276.38d {+18h 25m 32s}  -20.18d {-20d 10' 43"}
MOON_DIST:        37.85 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:       48.48,-15.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      307.70, 25.36 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 23 Sep 12 05:33:51 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     534402,   Seg_Num: 0
POINT_RA:        303.771d {+20h 15m 05s} (J2000)
POINT_DEC:        +6.231d {+06d 13' 53"} (J2000)
POINT_ROLL:      273.797d
IMG_START_DATE:  16193 TJD;   267 DOY;   12/09/23
IMG_START_TIME:  19825.94 SOD {05:30:25.94} UT,   859.7 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.412
N_STARS:         190
X_OFFSET:        102 [pixels]
Y_OFFSET:        427 [pixels]
X_MAX:           1541 [pixels]
Y_MAX:           1866 [pixels]
DET_THRESH:      13
PHOTO_THRESH:    7
SL_URL:          sw00534402000msufc0859.fits
SUN_POSTN:       180.55d {+12h 02m 11s}   -0.24d {-00d 14' 12"}
SUN_DIST:        123.19 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      276.39d {+18h 25m 33s}  -20.18d {-20d 10' 41"}
MOON_DIST:        37.85 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:       48.48,-15.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      307.70, 25.36 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 23 Sep 12 05:34:52 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     534402,   Seg_Num: 0
POINT_RA:        303.771d {+20h 15m 05s} (J2000)
POINT_DEC:        +6.231d {+06d 13' 53"} (J2000)
ROLL:            273.797d
IMG_START_DATE:  16193 TJD;   267 DOY;   12/09/23
IMG_START_TIME:  19825.94 SOD {05:30:25.94} UT,   859.7 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     370071035
X_OFFSET:        661 [pixels]
Y_OFFSET:        986 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       821
Y_GRB_POS:       1146
BINNING_INDEX:   1
IM_URL:          sw00534402000msuni0869.fits
SUN_POSTN:       180.55d {+12h 02m 11s}   -0.24d {-00d 14' 13"}
SUN_DIST:        123.19 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      276.40d {+18h 25m 36s}  -20.18d {-20d 10' 37"}
MOON_DIST:        37.84 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:       48.48,-15.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      307.70, 25.36 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 23 Sep 12 05:35:14 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     534402,   Seg_Num: 0
POINT_RA:        303.771d {+20h 15m 05s} (J2000)
POINT_DEC:        +6.231d {+06d 13' 53"} (J2000)
ROLL:            273.797d
IMG_START_DATE:  16193 TJD;   267 DOY;   12/09/23
IMG_START_TIME:  19825.94 SOD {05:30:25.94} UT,   859.7 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     370071035
X_OFFSET:        661 [pixels]
Y_OFFSET:        986 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       821
Y_GRB_POS:       1146
BINNING_INDEX:   1
IM_URL:          sw00534402000msuni0869.fits
SUN_POSTN:       180.55d {+12h 02m 11s}   -0.24d {-00d 14' 14"}
SUN_DIST:        123.19 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      276.40d {+18h 25m 37s}  -20.18d {-20d 10' 36"}
MOON_DIST:        37.84 [deg]
MOON_ILLUM:      55 [%]
GAL_COORDS:       48.48,-15.44 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      307.70, 25.36 [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 #13797
W. Zheng (U Mich) and T. Guver (Sabanci U) report on behalf of the ROTSE collaboration:
ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 120923A (Swift trigger 534402; Yershov et al., GCN 13796), producing images beginning 0.7 s after the GCN notice time. An automated response took the first image at 05:17:43.7 UT, 97.4 s after the burst, under fair conditions. We took 10 5-sec, 10 20-sec and 0 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. Individual images have limiting magnitudes ranging from 15.4-16.3; we set the following specific limits.
start UT end UT t_exp(s) mlim Coadd?
------------------------------------------------------
05:17:43 05:17:48 5 15.6 N
05:17:55 05:18:00 5 15.4 N
05:18:07 05:18:12 5 15.7 N
05:17:43 05:19:31 50 16.4 Y
GCN Circular #13798
Klotz A. (IRAP-CNRS-OMP), Gendre B. (ASDC/INAF-OAR), Boer M. (UNS-CNRS-OCA), Atteia J.L. (IRAP-CNRS-OMP) report:
We imaged the field of GRB 120923A detected by SWIFT (trigger 534402) with the TAROT robotic telescope (D=25cm) located at the European Southern Observatory, La Silla observatory, Chile.
The observations started 104.6s after the GRB trigger (16.8s after the notice). The elevation of the field decreased from 16 degrees above horizon and weather conditions were good.
The first image is trailed with a duration of 60.0s (see the description in Klotz et al., 2006, A&A 451, L39). We do not detect any OT at the XRT position (Yershov et al. GCNC 13796) with a limiting magnitude of:
t0+105s to t0+165s : R > 16.0
We co-added a series of exposures: t0+178s to t0+329s : R > 17.9
Magnitudes were estimated with the nearby USNO-B1 stars and are not corrected for galactic dust extinction.
Note that there is NOMAD1 0962-0583888 (R.A.=303.7958222 Decl=+06.2200278 J2000) R=17.9 very close to the XRT position. This source is detected on TAROT images but the sampling of TAROT (3.3 arcsec/pixel) does not allow to separate an OT from this star.
This message may be cited.
GCN Circular #13801
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team.
Using 1113 s of XRT Photon Counting mode data and 1 UVOT images for GRB 120923A, 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 = 303.79480, +6.22131 which is equivalent to:
```
RA (J2000): 20h 15m 10.75s
Dec (J2000): +06d 13' 16.7"
```
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 #13802
A.J. Levan (U. Warwick), D.A. Perley (Caltech), N.R. Tanvir (U. Leicester) and A. Cucchiara (UCSC) report for a larger collaboration:
"We observed the location of GRB 120923A (Yershov et al. GCN 13796) with Gemini-North, beginning approximately 1.4 hours after the burst. Observations were obtained in riz (with GMOS) and YJHK (with NIRI). In our optical and Y-band observations we detect no source in the refined XRT error circle (Goad et al. GCN 13801), with a preliminary z-band limit of z~24. However, in our JHK observations we clearly detect a source at a location of
```
RA(J2000): 20:15:10.78
DEC(J2000): 06:13:16.3
(uncertainty ~0.5")
```
Which is seen to fade in two epochs of J-band observations separated by ~3 hours, confirming it as the counterpart of GRB 120923A. The colours of this source in the IR are blue, with H-K~0.1 mag. This is strongly suggestive of a break between the Y and J-band, similar to GRB 090423, and may indicate that GRB 120923A lies at z~8.
We thank Michael Hoenig for excellent support for these observations.
Further observations are ongoing."
GCN Circular #13805
A. A. Breeveld (MSSL-UCL), V. N. Yershov (MSSL-UCL) and N. P. M. Kuin (MSSL-UCL) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 120923A 143 s after the BAT trigger (Yershov et al., GCN Circ. 13796). No optical afterglow consistent with the XRT or Gemini position (Goad et al., GCN Circ. 13801, Levan et al., GCN Circ. 13802) is detected in the initial UVOT exposure. A preliminary 3-sigma upper limit using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart exposure is:
```
Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white              143          293          147         >21.3
```
The magnitude in the table is not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.16 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #13807
C. B. Markwardt (GSFC), 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), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU), V. N. Yershov (UCL-MSSL) (i.e. the Swift-BAT team):
Using the data set from T-61 to T+242 sec from recent telemetry downlinks, we report further analysis of BAT GRB 120923A (trigger #534402) (Yershov, et al., GCN Circ. 13796). The BAT ground-calculated position is RA, Dec = 303.781, 6.255 deg, which is
```
   RA(J2000)  =  20h 15m 07.3s 
   Dec(J2000) = +06d 15' 16.8" 
```
with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 79%.
The mask-weighted light curve shows the burst starting at ~T-5 sec, peaking at ~T+25 sec, and ending at ~T+30 sec. T90 (15-350 keV) is 27.2 +- 3.0 sec (estimated error including systematics).
The time-averaged spectrum from T-2.93 to T+26.64 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index -0.29 +- 1.66, and Epeak of 44.4 +- 10.6 keV (chi squared 43.83 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 3.2 +- 0.8 x 10^-7 erg/cm2 and the 1-sec peak flux measured from T+24.67 sec in the 15-150 keV band is 0.6 +- 0.1 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.80 +- 0.23 (chi squared 51.10 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/534402/BA/
GCN Circular #13811
F. Knust (MPE Garching), S. Klose, A. Nicuesa Guelbenzu (both TLS Tautenburg), and J. Greiner (MPE Garching) report on behalf of the GROND team:
We observed the field of GRB 120923A (Swift trigger 534402; Yershov et al., GCN 13796) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG/ESO telescope at La Silla Observatory (Chile).
Observations started at 00:10 UT on Sep 24, 19 hrs after the GRB trigger, and are continuing. In a first 30 min exposure, at a mid time 00:35 UT, we do not detect any source at the position of the NIR transient reported by Levan et al. (GCN 13802) down to (AB mags, 3 sigma)
```
 
g' > 23.5, 
r' > 23.7, 
i' > 23.0, 
z' > 23.0, 
J  > 21.0, 
H  > 20.4. 
```
These uper limits are derived based on calibrating the images against GROND zeropoints and 2MASS field stars and are not corrected for the Galactic foreground extinction corresponding to a reddening of E_(B-V)= 0.15 mag in the direction of the burst (Schlegel et al. 1998).
GCN Circular #13812
J.A. Kennea (PSU), M.C. Stroh (PSU), D.N. Burrows (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), O.M. Littlejohns (U. Leicester), B. Sbarufatti (INAF-OAB/PSU), G. Stratta (ASDC), P. D'Avanzo (INAF-OAB) and V.N. Yershov report on behalf of the Swift-XRT team:
We have analysed 9.0 ks of XRT data for GRB 120923A (Yershov et al. GCN Circ. 13796), from 151 s to 57.5 ks after the BAT trigger. The data comprise 331 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Goad et al. (GCN. Circ 13801).
The light curve can be modelled with a power-law decay with a decay index of alpha=0.84 (+0.11, -0.09).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.78 (+0.47, -0.26). The best-fitting absorption column is 1.08 (+1.30, -0.10) x 10^21 cm^-2, consistent with the Galactic value of 9.8 x 10^20 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.2 x 10^-11 (5.1 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     1.08 (+1.30, -0.10) x 10^21 cm^-2
Galactic foreground: 9.8 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.78 (+0.47, -0.26)
```
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00534402.
This circular is an official product of the Swift-XRT team.
GCN Circular #13813
A. Zauderer, E. Berger, and T. Laskar (Harvard) report on behalf of a larger collaboration:
"We observed the position of GRB 120923A (Yershov et al; GCN 13796) beginning on 2012 Sep 24.02 UT (0.8 d after the burst) with the EVLA at a mean frequency of 5.8 GHz. We find no significant radio emission at the position of the near-IR counterpart (Levan et al; GCN 13802) or within the enhanced Swift/XRT error circle (Goad et al; GCN 13801) to a 3-sigma limit of 28 uJy."
GCN Circular #13814
A. Zauderer and E. Berger (Harvard) report on behalf of the CARMA Key Project "A Millimeter View of the Transient Universe":
"We observed the position of GRB 120923A (Yershov et al; GCN 13796) with the Combined Array for Research in Millimeter Astronomy (CARMA) beginning on 2012 Sep 23.99 UT (0.77 d after the burst). Observations were obtained at a mean frequency of ~85 GHz. We find no significant millimeter emission at the position of the near-IR counterpart (Levan et al; GCN 13802) or within the enhanced Swift/XRT error circle (Goad et al; GCN 13801) to a preliminary 3-sigma limit of 0.39 mJy."
GCN Circular #13815
J. Wren, W.T. Vestrand, P. Wozniak, and H. Davis, of Los Alamos National Laboratory report:
The RAPTOR network of robotic optical telescopes made observations of Swift trigger 534402 (Yershov, et al., GCN 13796). The burst location was within the field of our wide-field monitor located in Maui, HI, which began a 10 s integration of the location at 05:16:05.26 UT, 1.0 s before the Swift trigger time and during the gamma-ray emitting interval. The next 10 s exposure began at 05:16:23.26, 17.0 s after the Swift trigger and covering the peak emission detected by the BAT (Markwardt, et al., GCN 13807). The optical counterpart (Levan, et al., GCN 13802) was not detected above our 3-sigma limiting magnitude of 10.5 based on a comparison of our unfiltered image to the Tycho-2 V-band catalog.
GCN Circular #13817
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 the MITSuME collaboration:
We observed the field of GRB 120923A (Yershov et al., GCNC 13796) 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 2012-09-23 10:00:39 UT (~4.7 h after the burst) We did not find any new point source within the enhanced XRT circle (Goad et al., GCNC 13801) in all the three bands. We also could not detect the previously reported afterglow (Levan et al., GCNC 13802).
Three sigma upper limits of the OT are listed below. We used SDSS catalog for flux calibration.
```
T0+[day]   MID-UT   T-EXP[sec]    g'     Rc     Ic
------------------------------------------------------
0.23958    11:01:05    6360.0   >20.6  >20.2  >18.9
------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]
```
GCN Circular #13818
J. Wren, W.T. Vestrand, P. Wozniak, and H. Davis, of Los Alamos National Laboratory report:
The RAPTOR network of robotic optical telescopes made follow-up observations of Swift trigger 534402 (Yershov, et al., GCN 13796). Our narrow-field instruments in Los Alamos, NM, began imaging at 05:17:43.06 UT, 96.8 s after the Swift BAT trigger. We do not detect the optical counterpart (Levan, et al., GCN 13802) in any of our images. The following table summarizes some of our early observations. Our unfiltered images are calibrated to the USNO-B1 r-band. The start time is seconds since the BAT trigger time. The magnitude limit is the 3-sigma detection threshold.
```
T-Start    Exp-Time   Mag-Limit
----------------------------------
96.82      5.9        17.3
106.83     5.4        17.6
143.24     5.4        17.5
161.53     5.1        17.5
181.82     10.1       18.2
220.22     10.4       18.1
284.22     10.9       18.1
```
GCN Circular #13820
L. Elenin (KIAM), A. Volnova (SAI MSU, IKI), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:
We observed the field of the Swift GRB 120923A (Yershov et al., GCN 13796) with 0.45-m telescope of ISON-NM observatory starting on Sep. 23 (UT) 05:18:58, i.e 172 s after burst trigger. We took several unfiltered images of 30 s and 60 s exposures. We do not detect the optical counterpart (Levan et al., GCN 13802). A photometry of co-added frames is based on the USNO-B1.0 (R2) nearby stars is following:
```
  T0+,          Exposure,  OT,         UL (3 sigma)
  mid, d         (s)

0.00447      9x30           n/d           19.7
0.02839    53x30           n/d           20.5
```
GCN Circular #13823
M. Im (CEOU/SNU), H.-I. Sung (KASI), and Y. Urata (NCU) on behalf of a larger collaboration.
We observed the field of GRB 120923A (Yershov et al. GCN 13796) in JHK using KASINICS on the 1.8m telescope at the Bohyunsan observatory in Korea.
The observation started at 2012-09-29 11:30:43 UT, or about 6.25 hours after the BAT alert. The stacked JHK images do not reveal a convincing detection of the afterglow reported earlier (Levan et al. GCN 13802), to the limits of ~20 AB mag in H and K (3-sigma).
GCN Circular #13825
M. Im (CEOU/SNU) reports
The UT date reported in GCN 13823 should be 2012-09-23, rather than 2012-09-29. We thank J. Fynbo for spotting the error.
GCN Circular #18183
Xianggao Wang (UC Berkeley, GXU, UNLV), WeiKang Zheng, Alexei V. Filippenko (UC Berkeley), and S. Bradley Cenko (GSFC) report on behalf of the KAIT GRB team:
The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at Lick Observatory, responded to Swift GRBs 120422A (Troja et al., GCN 13243), 120724A (D'Avanzo et al., GCN 13510), 120803B (Racusin et al. GCN 13566), 120911A (Cannizzo et al., GCN 13744), and 120923A (Yershov et al., GCN 13796) at 510 s, 202 s, 196 s, 147 s, and 236 s after the burst, respectively. Observations were performed with an automatic sequence in the clear (roughly R), V, and I filters, and the exposure time was 20 s per image. We do not detect any new sources within the XRT error circles. We estimate the following upper limits (magnitudes) in clear-band images for each GRB calibrated to USNO B1.0:
```
GRB       Start-Time  Coadd-Images  Mid-time   Upper-Limit (3 sigma)
120422A   510 s        20 s x 6           758 s              20.6
120724A   202 s        20 s x 10         647 s              20.7
120803B   196 s        20 s x 10         644 s              21.7
120911A   147 s        20 s x 6          501 s               20.9
120923A   236 s        20 s x 6          563 s               21.0
```
Spectroscopic redshift of 7.8: Tanvir et al. 2018, ApJ 865, 107

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Jochen Greiner, last update: 22-Oct-2018 [Disclaimer]