Gamma-ray Burst 121027A

(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:     Sat 27 Oct 12 07:32:47 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     536831,   Seg_Num: 0
GRB_RA:           63.610d {+04h 14m 26s} (J2000),
                  63.669d {+04h 14m 41s} (current),
                  63.382d {+04h 13m 32s} (1950)
GRB_DEC:         -58.801d {-58d 48' 04"} (J2000),
                 -58.770d {-58d 46' 10"} (current),
                 -58.926d {-58d 55' 31"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       3707 [cnts]    Image_Peak=182 [image_cnts]
TRIGGER_DUR:     1.024 [sec] 
TRIGGER_INDEX:   146     E_range: 25-100 keV
BKG_INTEN:       22736 [cnts]
BKG_TIME:        27134.19 SOD {07:32:14.19} UT
BKG_DUR:         8 [sec]
GRB_DATE:        16227 TJD;   301 DOY;   12/10/27
GRB_TIME:        27149.74 SOD {07:32:29.74} UT
GRB_PHI:         156.40 [deg]
GRB_THETA:        23.69 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     13.82 [sigma]
IMAGE_SIGNIF:    7.88 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +2  -2  +0  +0 +23  +0 
SUN_POSTN:       212.03d {+14h 08m 06s}  -12.95d {-12d 56' 50"}
SUN_DIST:        103.80 [deg]   Sun_angle= 9.9 [hr] (West of Sun)
MOON_POSTN:        4.12d {+00h 16m 28s}   +6.16d {+06d 09' 45"}
MOON_DIST:        80.25 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      269.68,-42.98 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       20.37,-75.78 [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 = 238.77,-1.60 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 27 Oct 12 07:34:13 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     536831,   Seg_Num: 0
GRB_RA:           63.5959d {+04h 14m 23.01s} (J2000),
                  63.6545d {+04h 14m 37.08s} (current),
                  63.3682d {+04h 13m 28.36s} (1950)
GRB_DEC:         -58.8295d {-58d 49' 46.2"} (J2000),
                 -58.7978d {-58d 47' 52.0"} (current),
                 -58.9538d {-58d 57' 13.6"} (1950)
GRB_ERROR:       4.8 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       6.10e-09 [erg/cm2/sec]
GRB_SIGNIF:      12.40 [sigma]
IMG_START_DATE:  16227 TJD;   301 DOY;   12/10/27
IMG_START_TIME:  27217.08 SOD {07:33:37.08} UT,   67.3 [sec] since BAT Trigger Time
TAM[0-3]:        327.62 237.26 261.45 243.58
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       212.03d {+14h 08m 07s}  -12.95d {-12d 56' 51"}
SUN_DIST:        103.78 [deg]   Sun_angle= 9.9 [hr] (West of Sun)
MOON_POSTN:        4.13d {+00h 16m 31s}   +6.17d {+06d 10' 00"}
MOON_DIST:        80.25 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      269.72,-42.98 [deg] galactic lon,lat of the burst
ECL_COORDS:       20.27,-75.80 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 1.74 arcmin from the BAT position.  
COMMENTS:        The object found at this position is either a very bright burst or a cosmic ray hit.  
COMMENTS:        Examine the XRT Image to differentiate (CRs are much more compact); see examples at:  
COMMENTS:        http://www.swift.psu.edu/xrt/XRT_Postage_Stamp_Image_Photo_Gallery.htm .

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 27 Oct 12 07:34:32 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     536831,   Seg_Num: 0
GRB_RA:           63.5959d {+04h 14m 23.0s} (J2000),
                  63.6545d {+04h 14m 37.0s} (current),
                  63.3682d {+04h 13m 28.3s} (1950)
GRB_DEC:         -58.8295d {-58d 49' 46.2"} (J2000),
                 -58.7978d {-58d 47' 52.0"} (current),
                 -58.9538d {-58d 57' 13.6"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       154 [cnts]
IMG_START_DATE:  16227 TJD;   301 DOY;   12/10/27
IMG_START_TIME:  27217.08 SOD {07:33:37.08} UT,   67.3 [sec] since BAT Trigger Time
CENTROID_X:      277.52,  raw= 278  [pixels]
CENTROID_Y:      265.80,  raw= 266  [pixels]
ROLL:            148.26 [deg]
GAIN:            2
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -75.89
GRB_POS_XRT_Z:   -61.71
IMAGE_URL:       sw00536831000msxps_rw.img
SUN_POSTN:       212.03d {+14h 08m 07s}  -12.95d {-12d 56' 51"}
SUN_DIST:        103.78 [deg]   Sun_angle= 9.9 [hr] (West of Sun)
MOON_POSTN:        4.13d {+00h 16m 32s}   +6.17d {+06d 10' 04"}
MOON_DIST:        80.25 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      269.72,-42.98 [deg] galactic lon,lat of the burst
ECL_COORDS:       20.27,-75.80 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.  
COMMENTS:        The object found at this position is either a very bright burst or a cosmic ray hit.  
COMMENTS:        Examine the XRT Image to differentiate (CRs are much more compact); see examples at:  
COMMENTS:        http://www.swift.psu.edu/xrt/XRT_Postage_Stamp_Image_Photo_Gallery.htm .

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 27 Oct 12 07:34:24 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     536831,   Seg_Num: 0
GRB_RA:           63.5959d {+04h 14m 23.0s} (J2000),
                  63.6545d {+04h 14m 37.0s} (current),
                  63.3682d {+04h 13m 28.3s} (1950)
GRB_DEC:         -58.8295d {-58d 49' 46.2"} (J2000),
                 -58.7978d {-58d 47' 52.0"} (current),
                 -58.9538d {-58d 57' 13.6"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       154 [cnts]
IMG_START_DATE:  16227 TJD;   301 DOY;   12/10/27
IMG_START_TIME:  27217.08 SOD {07:33:37.08} UT,   67.3 [sec] since BAT Trigger Time
CENTROID_X:      277.52,  raw= 278  [pixels]
CENTROID_Y:      265.80,  raw= 266  [pixels]
ROLL:            148.26 [deg]
GAIN:            2
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -75.89
GRB_POS_XRT_Z:   -61.71
IMAGE_URL:       sw00536831000msxps_rw.img
SUN_POSTN:       212.03d {+14h 08m 07s}  -12.95d {-12d 56' 51"}
SUN_DIST:        103.78 [deg]   Sun_angle= 9.9 [hr] (West of Sun)
MOON_POSTN:        4.13d {+00h 16m 31s}   +6.17d {+06d 10' 02"}
MOON_DIST:        80.25 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      269.72,-42.98 [deg] galactic lon,lat of the burst
ECL_COORDS:       20.27,-75.80 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.  
COMMENTS:        The object found at this position is either a very bright burst or a cosmic ray hit.  
COMMENTS:        Examine the XRT Image to differentiate (CRs are much more compact); see examples at:  
COMMENTS:        http://www.swift.psu.edu/xrt/XRT_Postage_Stamp_Image_Photo_Gallery.htm .

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 27 Oct 12 07:36:27 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     536831,   Seg_Num: 0
GRB_RA:           63.610d {+04h 14m 26s} (J2000),
                  63.669d {+04h 14m 41s} (current),
                  63.382d {+04h 13m 32s} (1950)
GRB_DEC:         -58.801d {-58d 48' 04"} (J2000),
                 -58.770d {-58d 46' 10"} (current),
                 -58.926d {-58d 55' 31"} (1950)
GRB_DATE:        16227 TJD;   301 DOY;   12/10/27
GRB_TIME:        27149.74 SOD {07:32:29.74} UT
TRIGGER_INDEX:   146
GRB_PHI:         156.40 [deg]
GRB_THETA:        23.69 [deg]
DELTA_TIME:      45.00 [sec]
TRIGGER_DUR:     1.024 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     13.82 [sigma]
IMAGE_SIGNIF:    7.88 [sigma]
LC_URL:          sw00536831000msb.lc
SUN_POSTN:       212.03d {+14h 08m 07s}  -12.95d {-12d 56' 53"}
SUN_DIST:        103.80 [deg]   Sun_angle= 9.9 [hr] (West of Sun)
MOON_POSTN:        4.15d {+00h 16m 35s}   +6.17d {+06d 10' 24"}
MOON_DIST:        80.24 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      269.68,-42.98 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       20.37,-75.78 [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 = 238.77,-1.60 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 27 Oct 12 07:36:48 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     536831,   Seg_Num: 0
POINT_RA:         63.614d {+04h 14m 27s} (J2000)
POINT_DEC:       -58.803d {-58d 48' 12"} (J2000)
POINT_ROLL:      148.259d
IMG_START_DATE:  16227 TJD;   301 DOY;   12/10/27
IMG_START_TIME:  27226.69 SOD {07:33:46.69} UT,   76.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.410
N_STARS:         37
X_OFFSET:        448 [pixels]
Y_OFFSET:        560 [pixels]
X_MAX:           1407 [pixels]
Y_MAX:           1519 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00536831000msufc0076.fits
SUN_POSTN:       212.03d {+14h 08m 07s}  -12.95d {-12d 56' 53"}
SUN_DIST:        103.80 [deg]   Sun_angle= 9.9 [hr] (West of Sun)
MOON_POSTN:        4.15d {+00h 16m 36s}   +6.17d {+06d 10' 28"}
MOON_DIST:        80.24 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      269.68,-42.98 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       20.37,-75.79 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 27 Oct 12 07:37:10 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     536831,   Seg_Num: 0
POINT_RA:         63.614d {+04h 14m 27s} (J2000)
POINT_DEC:       -58.803d {-58d 48' 12"} (J2000)
POINT_ROLL:      148.259d
IMG_START_DATE:  16227 TJD;   301 DOY;   12/10/27
IMG_START_TIME:  27226.69 SOD {07:33:46.69} UT,   76.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.410
N_STARS:         37
X_OFFSET:        448 [pixels]
Y_OFFSET:        560 [pixels]
X_MAX:           1407 [pixels]
Y_MAX:           1519 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00536831000msufc0076.fits
SUN_POSTN:       212.03d {+14h 08m 07s}  -12.95d {-12d 56' 53"}
SUN_DIST:        103.80 [deg]   Sun_angle= 9.9 [hr] (West of Sun)
MOON_POSTN:        4.15d {+00h 16m 37s}   +6.18d {+06d 10' 31"}
MOON_DIST:        80.24 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      269.68,-42.98 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       20.37,-75.79 [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:     Sat 27 Oct 12 07:37:37 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     536831,   Seg_Num: 0
POINT_RA:         63.614d {+04h 14m 27s} (J2000)
POINT_DEC:       -58.803d {-58d 48' 12"} (J2000)
ROLL:            148.259d
IMG_START_DATE:  16227 TJD;   301 DOY;   12/10/27
IMG_START_TIME:  27226.69 SOD {07:33:46.69} UT,   76.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     373016036
X_OFFSET:        966 [pixels]
Y_OFFSET:        939 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1126
Y_GRB_POS:       1099
BINNING_INDEX:   1
IM_URL:          sw00536831000msuni0086.fits
SUN_POSTN:       212.03d {+14h 08m 07s}  -12.95d {-12d 56' 54"}
SUN_DIST:        103.80 [deg]   Sun_angle= 9.9 [hr] (West of Sun)
MOON_POSTN:        4.16d {+00h 16m 38s}   +6.18d {+06d 10' 36"}
MOON_DIST:        80.24 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      269.68,-42.98 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       20.37,-75.79 [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:     Sat 27 Oct 12 07:37:54 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     536831,   Seg_Num: 0
POINT_RA:         63.614d {+04h 14m 27s} (J2000)
POINT_DEC:       -58.803d {-58d 48' 12"} (J2000)
ROLL:            148.259d
IMG_START_DATE:  16227 TJD;   301 DOY;   12/10/27
IMG_START_TIME:  27226.69 SOD {07:33:46.69} UT,   76.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     373016036
X_OFFSET:        966 [pixels]
Y_OFFSET:        939 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1126
Y_GRB_POS:       1099
BINNING_INDEX:   1
IM_URL:          sw00536831000msuni0086.fits
SUN_POSTN:       212.03d {+14h 08m 07s}  -12.95d {-12d 56' 54"}
SUN_DIST:        103.80 [deg]   Sun_angle= 9.9 [hr] (West of Sun)
MOON_POSTN:        4.16d {+00h 16m 38s}   +6.18d {+06d 10' 39"}
MOON_DIST:        80.24 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      269.68,-42.98 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       20.37,-75.79 [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:     Sat 27 Oct 12 07:43:33 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     536831,   Seg_Num: 0
POINT_RA:         63.611d {+04h 14m 27s} (J2000)
POINT_DEC:       -58.806d {-58d 48' 19"} (J2000)
POINT_ROLL:      148.263d
IMG_START_DATE:  16227 TJD;   301 DOY;   12/10/27
IMG_START_TIME:  27438.65 SOD {07:37:18.65} UT,   288.9 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.398
N_STARS:         30
X_OFFSET:        646 [pixels]
Y_OFFSET:        619 [pixels]
X_MAX:           1605 [pixels]
Y_MAX:           1578 [pixels]
DET_THRESH:      6
PHOTO_THRESH:    2
SL_URL:          sw00536831000msufc0288.fits
SUN_POSTN:       212.03d {+14h 08m 08s}  -12.95d {-12d 56' 59"}
SUN_DIST:        103.80 [deg]   Sun_angle= 9.9 [hr] (West of Sun)
MOON_POSTN:        4.20d {+00h 16m 49s}   +6.19d {+06d 11' 39"}
MOON_DIST:        80.24 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      269.69,-42.98 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       20.36,-75.79 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 27 Oct 12 07:43:49 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     536831,   Seg_Num: 0
POINT_RA:         63.611d {+04h 14m 27s} (J2000)
POINT_DEC:       -58.806d {-58d 48' 19"} (J2000)
POINT_ROLL:      148.263d
IMG_START_DATE:  16227 TJD;   301 DOY;   12/10/27
IMG_START_TIME:  27438.65 SOD {07:37:18.65} UT,   288.9 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.398
N_STARS:         30
X_OFFSET:        646 [pixels]
Y_OFFSET:        619 [pixels]
X_MAX:           1605 [pixels]
Y_MAX:           1578 [pixels]
DET_THRESH:      6
PHOTO_THRESH:    2
SL_URL:          sw00536831000msufc0288.fits
SUN_POSTN:       212.03d {+14h 08m 08s}  -12.95d {-12d 56' 59"}
SUN_DIST:        103.80 [deg]   Sun_angle= 9.9 [hr] (West of Sun)
MOON_POSTN:        4.21d {+00h 16m 50s}   +6.19d {+06d 11' 41"}
MOON_DIST:        80.24 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      269.69,-42.98 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       20.36,-75.79 [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:     Sat 27 Oct 12 07:44:43 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     536831,   Seg_Num: 0
POINT_RA:         63.611d {+04h 14m 27s} (J2000)
POINT_DEC:       -58.806d {-58d 48' 19"} (J2000)
ROLL:            148.263d
IMG_START_DATE:  16227 TJD;   301 DOY;   12/10/27
IMG_START_TIME:  27438.65 SOD {07:37:18.65} UT,   288.9 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     373016248
X_OFFSET:        966 [pixels]
Y_OFFSET:        939 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1126
Y_GRB_POS:       1099
BINNING_INDEX:   1
IM_URL:          sw00536831000msuni0298.fits
SUN_POSTN:       212.03d {+14h 08m 08s}  -12.95d {-12d 57' 00"}
SUN_DIST:        103.80 [deg]   Sun_angle= 9.9 [hr] (West of Sun)
MOON_POSTN:        4.21d {+00h 16m 51s}   +6.20d {+06d 11' 51"}
MOON_DIST:        80.23 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      269.69,-42.98 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       20.36,-75.79 [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:     Sat 27 Oct 12 07:44:57 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     536831,   Seg_Num: 0
POINT_RA:         63.611d {+04h 14m 27s} (J2000)
POINT_DEC:       -58.806d {-58d 48' 19"} (J2000)
ROLL:            148.263d
IMG_START_DATE:  16227 TJD;   301 DOY;   12/10/27
IMG_START_TIME:  27438.65 SOD {07:37:18.65} UT,   288.9 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     373016248
X_OFFSET:        966 [pixels]
Y_OFFSET:        939 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1126
Y_GRB_POS:       1099
BINNING_INDEX:   1
IM_URL:          sw00536831000msuni0298.fits
SUN_POSTN:       212.04d {+14h 08m 08s}  -12.95d {-12d 57' 00"}
SUN_DIST:        103.80 [deg]   Sun_angle= 9.9 [hr] (West of Sun)
MOON_POSTN:        4.22d {+00h 16m 52s}   +6.20d {+06d 11' 53"}
MOON_DIST:        80.23 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      269.69,-42.98 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       20.36,-75.79 [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:     Sat 27 Oct 12 07:50:08 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     536831,   Seg_Num: 0
POINT_RA:         63.611d {+04h 14m 27s} (J2000)
POINT_DEC:       -58.805d {-58d 48' 18"} (J2000)
POINT_ROLL:      148.263d
IMG_START_DATE:  16227 TJD;   301 DOY;   12/10/27
IMG_START_TIME:  28017.32 SOD {07:46:57.32} UT,   867.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.463
N_STARS:         104
X_OFFSET:        406 [pixels]
Y_OFFSET:        379 [pixels]
X_MAX:           1845 [pixels]
Y_MAX:           1818 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00536831000msufc0867.fits
SUN_POSTN:       212.04d {+14h 08m 09s}  -12.95d {-12d 57' 04"}
SUN_DIST:        103.80 [deg]   Sun_angle= 9.9 [hr] (West of Sun)
MOON_POSTN:        4.26d {+00h 17m 02s}   +6.21d {+06d 12' 48"}
MOON_DIST:        80.23 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      269.69,-42.98 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       20.36,-75.79 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 27 Oct 12 07:50:33 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     536831,   Seg_Num: 0
POINT_RA:         63.611d {+04h 14m 27s} (J2000)
POINT_DEC:       -58.805d {-58d 48' 18"} (J2000)
POINT_ROLL:      148.263d
IMG_START_DATE:  16227 TJD;   301 DOY;   12/10/27
IMG_START_TIME:  28017.32 SOD {07:46:57.32} UT,   867.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.463
N_STARS:         104
X_OFFSET:        406 [pixels]
Y_OFFSET:        379 [pixels]
X_MAX:           1845 [pixels]
Y_MAX:           1818 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00536831000msufc0867.fits
SUN_POSTN:       212.04d {+14h 08m 09s}  -12.95d {-12d 57' 05"}
SUN_DIST:        103.80 [deg]   Sun_angle= 9.9 [hr] (West of Sun)
MOON_POSTN:        4.26d {+00h 17m 03s}   +6.21d {+06d 12' 52"}
MOON_DIST:        80.23 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      269.69,-42.98 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       20.36,-75.79 [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:     Sat 27 Oct 12 07:50:50 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     536831,   Seg_Num: 0
GRB_RA:           63.5977d {+04h 14m 23.44s} (J2000),
                  63.6563d {+04h 14m 37.51s} (current),
                  63.3700d {+04h 13m 28.80s} (1950)
GRB_DEC:         -58.8297d {-58d 49' 46.9"} (J2000),
                 -58.7980d {-58d 47' 52.7"} (current),
                 -58.9540d {-58d 57' 14.3"} (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:  16227 TJD;   301 DOY;   12/10/27
IMG_START_TIME:  27664.00 SOD {07:41:04.00} UT,   514.3 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       212.04d {+14h 08m 09s}  -12.95d {-12d 57' 05"}
SUN_DIST:        103.78 [deg]   Sun_angle= 9.9 [hr] (West of Sun)
MOON_POSTN:        4.26d {+00h 17m 03s}   +6.22d {+06d 12' 55"}
MOON_DIST:        80.23 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      269.72,-42.97 [deg] galactic lon,lat of the burst
ECL_COORDS:       20.27,-75.80 [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:     Sat 27 Oct 12 07:51:42 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     536831,   Seg_Num: 0
POINT_RA:         63.611d {+04h 14m 27s} (J2000)
POINT_DEC:       -58.805d {-58d 48' 18"} (J2000)
ROLL:            148.263d
IMG_START_DATE:  16227 TJD;   301 DOY;   12/10/27
IMG_START_TIME:  28017.32 SOD {07:46:57.32} UT,   867.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     373016827
X_OFFSET:        965 [pixels]
Y_OFFSET:        938 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1125
Y_GRB_POS:       1098
BINNING_INDEX:   1
IM_URL:          sw00536831000msuni0877.fits
SUN_POSTN:       212.04d {+14h 08m 10s}  -12.95d {-12d 57' 06"}
SUN_DIST:        103.80 [deg]   Sun_angle= 9.9 [hr] (West of Sun)
MOON_POSTN:        4.27d {+00h 17m 05s}   +6.22d {+06d 13' 04"}
MOON_DIST:        80.23 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      269.69,-42.98 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       20.36,-75.79 [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 Circular #13906
P. A. Evans (U Leicester), C. Gronwall (PSU), H. A. Krimm (CRESST/GSFC/USRA), C. B. Markwardt (NASA/GSFC), K. L. Page (U Leicester) and M. H. Siegel (PSU) report on behalf of the Swift Team:
At 07:32:29 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 121027A (trigger=536831). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 63.610, -58.801 which is
```
    RA(J2000) = 04h 14m 26s
    Dec(J2000) = -58d 48' 04"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multi-peaked structure with a duration of about 80 sec. The peak count rate was ~2000 counts/sec (15-350 keV), at ~3 sec after the trigger.
The XRT began observing the field at 07:33:37.0 UT, 67.4 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source with an enhanced position: RA, Dec 63.5977, -58.8298 which is equivalent to:
```
    RA(J2000)  = 04h 14m 23.44s
    Dec(J2000) = -58d 49' 47.2"
```
with an uncertainty of 2.5 arcseconds (radius, 90% containment). This location is 106 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper.
A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 1.50 x 10^20 cm^-2 (Kalberla et al. 2005).
The initial flux in the 2.5 s image was 6.10e-09 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 250 seconds with the U filter starting 288 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 19.2 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 18.0 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.02.
Due to the maintenance work at Goddard this weekend (GCN 13905) there may be a delay in receiving the full dataset, and thus refined analyses may not be available until late Sunday/early Monday.
Burst Advocate for this burst is P. A. Evans (pae9 AT star.le.ac.uk). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.)
GCN Circular #13907
P. A. Evans (U Leicester), C. Gronwall (PSU), H. A. Krimm (CRESST/GSFC/USRA), C. B. Markwardt (NASA/GSFC), K. L. Page (U Leicester) and M. H. Siegel (PSU) report on behalf of the Swift Team:
At 07:32:29 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 121027A (trigger=536831). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 63.610, -58.801 which is
```
   RA(J2000) = 04h 14m 26s
   Dec(J2000) = -58d 48' 04"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multi-peaked structure with a duration of about 80 sec. The peak count rate was ~2000 counts/sec (15-350 keV), at ~3 sec after the trigger.
The XRT began observing the field at 07:33:37.0 UT, 67.4 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 63.59612, -58.82887 which is equivalent to:
```
   RA(J2000)  = 04h 14m 23.07s
   Dec(J2000) = -58d 49' 43.9"
```
with an uncertainty of 4.0 arcseconds (radius, 90% containment). This location is 103 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 1.50 x 10^20 cm^-2 (Kalberla et al. 2005).
The initial flux in the 2.5 s image was 6.10e-09 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 250 seconds with the U filter starting 288 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 19.2 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 18.0 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.02.
Due to the maintenance work at Goddard this weekend (GCN 13905) there may be a delay in receiving the full dataset, and thus refined analyses may not be available until late Sunday/early Monday.
Burst Advocate for this burst is P. A. Evans (pae9 AT star.le.ac.uk). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.)

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 27 Oct 12 07:51:48 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     536831,   Seg_Num: 0
POINT_RA:         63.611d {+04h 14m 27s} (J2000)
POINT_DEC:       -58.805d {-58d 48' 18"} (J2000)
ROLL:            148.263d
IMG_START_DATE:  16227 TJD;   301 DOY;   12/10/27
IMG_START_TIME:  28017.32 SOD {07:46:57.32} UT,   867.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     373016827
X_OFFSET:        965 [pixels]
Y_OFFSET:        938 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1125
Y_GRB_POS:       1098
BINNING_INDEX:   1
IM_URL:          sw00536831000msuni0877.fits
SUN_POSTN:       212.04d {+14h 08m 10s}  -12.95d {-12d 57' 06"}
SUN_DIST:        103.80 [deg]   Sun_angle= 9.9 [hr] (West of Sun)
MOON_POSTN:        4.27d {+00h 17m 05s}   +6.22d {+06d 13' 05"}
MOON_DIST:        80.23 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      269.69,-42.98 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       20.36,-75.79 [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/MAXI NOTICE
NOTICE_DATE:     Sat 27 Oct 12 08:20:51 UT
NOTICE_TYPE:     MAXI Unknown Source Position
EVENT_ID_NUM:    227291276
EVENT_RA:         64.63d {+04h 18m 31s} (J2000),
                  64.69d {+04h 18m 46s} (current),
                  64.39d {+04h 17m 33s} (1950)
EVENT_DEC:       -57.86d {-57d 51' 21"} (J2000),
                 -57.83d {-57d 49' 31"} (current),
                 -57.98d {-57d 58' 32"} (1950) 
EVENT_ERROR:     1.0 [deg radius, stat+sys, 90% containment]
EVENT_FLUX:      402.0 +- 0.0 [mCrab] 
EVENT_DATE:      16227 TJD;   301 DOY;   12/10/27
EVENT_TIME:      29573.00 SOD {08:12:53.00} UT
EVENT_TSCALE:    1s
EVENT_EBAND:     Low, 2-4 keV
SUN_POSTN:       212.06d {+14h 08m 14s}  -12.96d {-12d 57' 30"}
SUN_DIST:        104.31 [deg]
MOON_POSTN:        4.51d {+00h 18m 02s}   +6.30d {+06d 18' 10"}
MOON_DIST:        80.20 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      268.23,-42.77 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       24.58,-75.48 [deg] ecliptic lon,lat of the burst (or transient)       
COMMENTS:        MAXI Unknown Source Position. GRB or unknown X-ray Transient.

GCN Circular #13908
M. Serino (RIKEN), S. Nakahira (JAXA), N. Negoro, M. Asada (Nihon U.), K. Yamaoka (ISAS), S. Ueno, H. Tomida, M. Ishikawa (JAXA), T. Mihara, M. Sugizaki, T. Yamamoto, J. Sugimoto, M. Matsuoka (RIKEN), N. Kawai, M. Morii, R. Usui, K. Ishikawa, T. Yoshii (Tokyo Tech), A. Yoshida (AGU), H. Tsunemi, M. Kimura (Osaka U.), M. Nakajima (Nihon U.), Y. Ueda, K. Hiroi, M. Shidatsu, R. Sato (Kyoto U.), Y. Tsuboi, M. Higa (Chuo U.) M. Yamauchi, Y. Nishimura, T. Hanayama, K. Yoshidome (Miyazaki U.) report on behalf of the MAXI team:
At 2012-10-27T08:12:53UT, the MAXI/GSC nova alert system triggered on a bright uncatalogued X-ray transient source. The transient emission lasted at least 38 seconds within the 41 second long triangular transit response of MAXI/GSC.
Assuming that the source flux was constant over the transit, we obtain the source position at
(R.A., Dec) = (63.75 deg, -58.68 deg) = (04:15:00, -58:40:59)(J2000)
with a 90% C.L. statistical error of 0.43 deg and an additional systematic uncertainty of 0.1 deg (90% containment radius). The 4-10 keV flux was ~150 mCrab.
The position is consistent with GRB 121027A (GCN 13906, 13907), so we identify the source is GRB 121027A observed 40 minutes after the Swift Trigger.
There was no significant excess flux in the previous transit at 06:40 UT (92 min before the trigger time) with an upper limit of 20 mCrab.
GCN Circular #13910
S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), P. A. Evans (U Leicester), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team):
Using the data set from T-61 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 121027A (trigger #536831) (Evans, et al., GCN Circ. 13906 (not 13907)). The BAT ground-calculated position is RA, Dec = 63.598, -58.839 deg, which is
```
   RA(J2000)  =  04h 14m 23.5s 
   Dec(J2000) = -58d 50' 21.3" 
```
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 80%.
The mask-weighted light curve shows a FRED with two small peaks on the tail, starting at ~T-9 sec, peaking at ~T+3 sec, with a long tail out to ~T+105 sec (or possibly to ~T+165 sec). T90 (15-350 keV) is 62.6 +- 4.8 sec (estimated error including systematics).
The time-averaged spectrum from T-9.34 to T+65.33 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.82 +- 0.09. The fluence in the 15-150 keV band is 2.0 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+2.00 sec in the 15-150 keV band is 1.3 +- 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/536831/BA/
GCN Circular #13911
R.L.C. Starling (U. Leicester), A.J. Levan (U. Warwick), K. Wiersema (U. Leicester), A. Lopez Garcia (AAO/Macquarie University), N.R. Tanvir (U. Leicester), T. Young (ANU), L. Spitler (Macquarie University/AAO) and S. Lee (AAO) report:
We triggered near-infrared observations with IRIS2 on the Anglo-Australian Telescope for GRB 121027A, beginning ~3.5 hours after the Swift BAT trigger (Evans et al. GCN Circ. 13907).
The field was observed for 2x10 minutes in each of J, H and K bands. In a preliminary analysis of the K band data (beginning 13:49 UT) we clearly detect a source within the enhanced XRT error circle (www.swift.ac.uk/sper/536831) at position:
```
RA   04 14 23.44
Dec -58 49 47.4 (J2000)
```
with approximate magnitude K(AB)=21.10 +/- 0.13.
The source is not discernable from the J and H band images. These, however, do not go as deep owing to variable weather conditions; the limiting magnitude in H(AB) is 21.3 (3-sigma, beginning 13:22 UT).
These data were obtained under programme AAT/12B/30.
GCN Circular #13916
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team.
Using 661 s of XRT Photon Counting mode data and 1 UVOT images for GRB 121027A, 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 = 63.59738, -58.82962 which is equivalent to:
```
RA (J2000): 04h 14m 23.37s
Dec (J2000): -58d 49' 46.6"
```
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 #13920
A.J. Levan (U. Warwick), R.Starling, N.R. Tanvir, K. Wiersema (U. Leicester), A. R. Lopez-Sanchez (AAO/Macquarie University), T. Young (ANU), K. Glazebrook (Swinburne), L. Spitler (Macquarie University/AAO), and S. Lee (AAO) report:
"We observed the candidate afterglow of GRB 121027A (Evans et al. GCN 13906; Starling et al. GCN 13916) with the Anglo Australian Telescope for a second epoch on the night of 28 October 2012. The second epoch was obtained ~32 hours after the burst, and 26 hours after the first epoch reported in Starling et al. (GCN 13916). We clearly detect the afterglow candidate, and find that it has brightened by approximately 1 magnitude in the K-band between the two epochs. This confirms it as the infrared afterglow of GRB 121027A. We note that rising behaviour in the IR over this time period is extremely unusual, and given the extremely bright, and long lived X-ray afterglow (e.g. Serino et al. GCN 13908) could be indicative of an event similar in nature to Swift J1644+57."
GCN Circular #13921
P. A. Evans, K.L. Page and J.P. Osborne (U Leicester) report on behalf of the Swift-XRT team:
We have analysed 12 ks of XRT data for GRB 121027A (Evans et al. GCN Circ. 13906), from 57 s to 76.2 ks after the BAT trigger. The data comprise 2.0 ks in Windowed Timing (WT) mode (the first 9 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN. Circ 13916).
This burst is unusual in showing multiple strong rebrightenings at high flux in X-rays, a rebrightening has also reported in the IR (Levan et al GCN 13920). This behaviour is reminiscent of the tidal disruption event Swift J1644.
The light curve initially follows a power-law decay with an index of alpha~1.8. This is interrupted by a flare beginning at T+220 s and lasting ~300 s, after which the decay appears much steeper: alpha~6.6. However at T+800 s the count rate jumps sharply, increasing by more than 2 orders of magnitude in under 300 s; by T+1.1 ks the count rate is ~30 ct/sec, corresponding to an observed flux of ~1e-9 erg/cm^2/s. At this point the GRB left Swift's observing window, however during the next observation (T+5.3 ks to T+6ks) the count rate remained high, increasing from ~20 ct/s at the start of the observation to ~60 ct/s at the end. The MAXI observation (GCN 13908) occurred between these observations, and the flux reported by MAXI is consistent with the Swift flux of ~1-2 e-9 erg cm^2/s. Over the next 4 exposures (T+11 ks to T+30 ks), the count-rate declines with an index of ~3.8 to a level of ~0.08 ct/s, it then remains at that level until T+76 ks, where our current observations end. The hardness ratio follows the count-rate during the rebrightenings (i.e. the emission is harder when brighter), which is typical of flaring activity.
A spectrum formed from the first observation in WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.55 (+/-0.06). The best-fitting absorption column is 2.80 (+0.16, -0.15) x 10^21 cm^-2, in excess of the Galactic value of 1.5 x 10^20 cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a photon index of 1.94 (+0.29, -0.27) and a best-fitting absorption column of 1.1 (+0.7, -0.6) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.8 x 10^-11 (4.8 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     1.1 (+0.7, -0.6) x 10^21 cm^-2
Galactic foreground: 1.5 x 10^20 cm^-2
Excess significance: 2.5 sigma
Photon index:	     1.94 (+0.29, -0.27)
```
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00536831.
Multi-wavelength follow-up is strongly recommended.
This circular is an official product of the Swift-XRT team.
GCN Circular #13922
H. Levato and C. Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)
C. Mallamaci, C. Lopez and F. Podest Observatorio Astronomico Felix Aguilar (OAFA)
E. Gorbovskoy, V. Lipunov, V. Kornilov, D. Denisenko, A. Kuznetsov, D. Kuvshinov, A. Belinski, N. Tyurina, N. Shatskiy, P. Balanutsa, D. Zimnukhov, V.V. Chazov Lomonosov Moscow State University, Sternberg Astronomical Institute
A. Tlatov, A.V. Parhomenko, D. Dormidontov, V. Sennik Kislovodsk Solar Station of the Pulkovo Observatory
K. Ivanov, S. Yazev, N.M. Budnev, O. Gres, O. Chuvalaev, V.A. Poleshchuk Irkutsk State University
V. Yurkov, Yu. Sergienko, D. Varda, E. Sinyakov Blagoveschensk Educational State University, Blagoveschensk
V. Krushinski, I. Zalozhnich, A. Popov, A. Bourdanov Ural Federal University
MASTER-ICATE robotic Very Wide Field Cameras (FOV=2x384 square degrees, D=72mm, f/1.2, 1 pix = 22 arcsec, http://observ.pereplet.ru) located in Argentina (Observatorio Astronomico Felix Aguilar, http://93.180.27.230:8080/) were pointed to the GRB 121027A by Swift trigger (Evans et al., GCNC 13906) 85 s after GRB time at 2012-10-27 07:33:54 UT. We haven`t found optical transient within Swift XRT error-box on our first (1 s exposure) set and on coadd image with complete exposure of 11 seconds during gamma-burst activity (Barthelmy et al., GCN 13910).
The 5-sigma upper limit on unfiltered (with respect to Tyho V mag) single image has been about 11.0 mag and 11.7 mag on coadded image.
The automatic photometry is:
```
Date         time     Exp.time	Limit
                        Coadd

2012-10-27 07:33:54     11      11.7
2012-10-27 07:35:05     41      12.2
2012-10-27 07:37:25     7       11.2
2012-10-27 07:38:16     80      11.7
2012-10-27 07:44:18     17      11.2
2012-10-27 07:45:18     75      12.2
2012-10-27 07:50:38     11      11.6
2012-10-27 07:51:03     26      12.1
2012-10-27 07:51:56     30      12.2
```
Our cameras are continuously imaging the sky with 1 sec exposures without time gap.
This message can be cited.
GCN Circular #13926
V. Sudilovsky (MPE Garching), D. A. Kann (MPE Garching/Universe Cluster), T. Kr"uhler (DARK, Copenhagen), and J. Greiner (MPE Garching) report on behalf of the GROND team:
Following two days of bad weather delay, we observed the field of GRB 121027A (Evans et al., GCN 13906) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP, 120, 405) mounted on the 2.2 m MPG/ESO telescope at La Silla Observatory (Chile).
Observations began at 08:10 on October 29th (mid-time ~2.05 days post-trigger). They were performed at an average seeing of 1.6" (r'-band) and at an average airmass of 1.2.
We detect the NIR afterglow reported by Starling et al. (GCN 13911) and Levan et al. (GCN 13920) in all seven bands.
Based on a 460 sec integration in g'r'i'z' and 1200 sec integration in JHK, we measure preliminary magnitudes (all in AB system) of
```
g' = 22.1 +/- 0.2 mag
r' = 21.6 +/- 0.1 mag
i' = 21.3 +/- 0.1 mag
z' = 20.9 +/- 0.1 mag
J  = 20.4 +/- 0.1 mag
H  = 19.7 +/- 0.1 mag
K  = 19.0 +/- 0.1 mag
```
We note an increase of brightness by ~ 1 magnitude relative to the observations reported by Levan et al. (GCN 13920) at 32 hours after the GRB.
Our detection in all bands constrains the redshift of this burst to z < 3.5.
Given magnitudes are calibrated against GROND zeropoints in the optical, and 2MASS field stars in the NIR, and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E(B-V) = 0.02 mag in the direction of the burst (Schlegel et al. 1998).
GCN Circular #13929
N. R. Tanvir, K. Wiersema (U. Leicester), A. J. Levan (U. Warwick), R. L. C. Starling (U. Leicester), S. Margheim, T. Hayward (Gemini) report:
We observed the counterpart of GRB 121027A (Starling et al. GCN 13911; Levan et al. GCN 13920; Sudilovsky et al. GCN 13926 ) with the GMOS-S spectrograph at Gemini-South, beginning at Oct 29 2012 05:42 UT. The spectrum covers a wavelength range of roughly 5200A to 7900A, and was obtained in rather poor conditions. Our provisional reduction shows a generally featureless trace, with only one significant absorption feature, at about 7770A. If we identify this feature with the MgII doublet at 2796/2803A (the poor S/N and low resolution make it unclear whether or not the observed line is a doublet), it would imply a redshift of z=1.77. Whilst this is perhaps the most likely identification, further observations are encouraged to test this possibility.
GCN Circular #13930
T. Kruehler (DARK), N. R. Tanvir (U. Leicester), A. de Ugarte Postigo (IAA-CSIC and DARK/NBI), D. Malesani (DARK), J. Fynbo (DARK), A. Melandri (INAF-OAB), A. J. Levan (U. Warwick), K. Wiersema (U. Leicester), S. Schulze (PUC and MCSS), P. Goldoni (APC,CEA/Irfu), H. Flores (Obs. Paris) and L. Kaper (U. Amsterdam) report on behalf of a larger collaboration:
We observed the optical/NIR counterpart (Starling et al. GCN 13911, Levan et al. GCN 13920, Sudilovsky et al. GCN 13926) of GRB 121027A (Evans et al. GCN 13906) with the VLT/X-shooter spectrograph, beginning at Oct 30 2012 04:52 UT, which is 2.89 days after the GRB.
We identify emission lines of [OIII]4959 and [OIII]5007, and several absorption lines of CIV, AlII, AlIII, MgI, MgII and FeII at a common redshift of z=1.773. This confirms the provisional redshift given in Tanvir et al. (GCN 13929) for this GRB.
We note that the afterglow remains remarkably bright at 2.9 days post burst. From the photometry of the acquisition image, we measure R = 21.15 +- 0.05 assuming R = 15.96 for the USNO star 0311-0027010 at RA = 04:14:21.83, Dec = -58:50:28.8.
We thank the VLT staff, in particular Linda Schmidtobreick and Myriam Rodrigues, for their assistance in obtaining these data, and acknowledge J. Elliott for private information about the transient brightness.
GCN Circular #13932
F. E. Marshall (NASA/GSFC) and P. A. Evans (U. Leicester) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 121027A 77 s after the BAT trigger (Evans et al., GCN Circ. 13906). A source consistent with the XRT position (Beardmore et al. GCN Circ. 13916) and the nIR position (Starling et al. GCN Circ. 13911) is weakly detected in the initial UVOT exposures.
The preliminary detection and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white               77         1192          353         21.55 +/- 0.25
v                  619         1239           75        >19.5
b                  544         1167           58        >19.7
u                  289         1143          285        >20.6
w1                 668         1118           58        >19.8
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.02 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #13937
J. Greiner (MPE Garching), A. Belloche, T. Csengeri, F. Wyrowski (all MPIfR Bonn), F. Schuller, F. Montenegro (both APEX, ESO), V. Sudilovsky, J. Elliott (both MPE Garching), D. A. Kann (MPE Garching/Universe Cluster), A. de Ugarte Postigo (IAA-CSIC Granada/DARK Copenhagen), T. Kruehler (DARK Copenhagen) report:
We observed the afterglow of the peculiar GRB 121027A (Starling et al. 2012, GCN 13911; Levan et al. 2012, GCN 13920; Evans et al. 2012, GCN 13921) with LABOCA/APEX at 870 micron. The observations in photometry mode started on Oct. 31, 7:57 UT, 4.02 days after the Swift trigger (Evans et al. 2012, GCN 13906, Barthelmy et al. 2012, GCN 13910). They were performed under good weather conditions (pwv ~ 1 mm), and lasted for 1 hr.
No source is detected, down to a 3 sigma upper limit of 21 mJy/beam.
1302.2352 from 12 Feb 13
A.J. Levan et al.: A new population of ultra-long duration gamma-ray bursts
We present comprehensive multiwavelength observations of three gamma-ray bursts (GRBs) with durations of several thousand seconds. We demonstrate that these events are extragalactic transients; in particular we resolve the long-standing conundrum of the distance of GRB 101225A (the "Christmas-day burst"), finding it to have a redshift z=0.847, and showing that two apparently similar events (GRB 111209A and GRB 121027A) lie at z=0.677 and z=1.773 respectively. The systems show extremely unusual X-ray and optical lightcurves, very different from classical GRBs, with long lasting highly variable X-ray emission and optical light curves that exhibit little correlation with the behaviour seen in the X-ray. Their host galaxies are faint, compact, and highly star forming dwarf galaxies, typical of "blue compact galaxies". We propose that these bursts are the prototypes of a hitherto largely unrecognized population of ultra-long GRBs, that while observationally difficult to detect may be astrophysically relatively common. The long durations may naturally be explained by the engine driven explosions of stars of much larger radii than normally considered for GRB progenitors which are thought to have compact Wolf-Rayet progenitor stars. However, we cannot unambiguously identify supernova signatures within their light curves or spectra. We also consider the alternative possibility that they arise from the tidal disruption of stars by supermassive black holes.
1302.4876 from 21 Feb 13
Fang-kun Peng et al.: GRB 121027A: long-lasting, energetic X-ray flares and clues to radiation mechanism and progenitor star
GRB 121027A is un-usual with its extremely long-lasting, energetic X-ray flares. The total energy release in X-ray flares is about one order of magnitude higher than prompt gamma-rays, making it special from most long GRBs. We show that while the prompt gamma-ray emission satisfies the empirical E_{iso}-E_{p} relation of typical long GRBs, the X-ray flares, whose spectra can be fit with a cutoff-power-law model with well-constrained E_p, significantly deviate from such a relation. Nonetheless, a time-resolved spectral analysis of X-ray flares suggest that the X-ray emission is consistent with the L_{iso}-E_{p} relation of long GRBs. We constrain the minimum Lorentz factor of the X-ray flares to be ~14, which is consistent with the Gamma-L_{iso} relation. Our results imply that prompt gamma-ray emission and late X-ray flares share the similar radiation mechanism, but originate from the outflows with different Lorentz factors. We search for similar GRBs from the Swift GRB archives, and find that the z=6.29 GRB 050904 is a carbon copy of GRB 121027A. The long-lasting, energetic X-ray flares in these GRBs demand significant accretion at late times, which point towards a large-radius progenitor star.
1302.4878 from 21 Feb 13
Xue-Feng Wu et al.: Giant X-ray Bump in GRB 121027A: Evidence for Fall-back Disk Accretion
The most interesting discovery in GRB 121027A is the giant X-ray bump detected by Swift/XRT. The X-ray afterglow re-brightens sharply at ~ 1000 s since the trigger by more than two orders of magnitude in less than 200 s. This X-ray bump lasts for more than 10 ks. It is quite different with typical X-ray flares. In this paper we propose a fallback accretion model to interpret this X-ray bump within the context of collapse of a massive star for long duration gamma-ray bursts. The required fallback radius ~ 3.5e10 cm and mass ~ 2.6 solar mass imply that a significant part of the helium envelope should be survived through the mass loss during the last stage of the massive progenitor of GRB 121027A.
1605.04660 from 17 May 16
He Gao et al.: Black hole central engine for ultra-long gamma-ray burst 111209A and its associated supernova 2011kl
Recently, the first association between an ultra-long gamma-ray burst (GRB) and a supernova is reported, i.e., GRB 111209A/SN 2011kl, which enables us to investigate the physics of central engines or even progenitors for ultra-long GRBs. In this paper, we inspect the broad-band data of GRB 111209A/SN 2011kl. The late-time X-ray lightcurve exhibits a GRB 121027A-like fall-back bump, suggesting a black hole central engine. We thus propose a collapsar model with fall-back accretion for GRB 111209A/SN 2011kl. The required model parameters, such as the total mass and radius of the progenitor star, suggest that the progenitor of GRB 111209A is more likely a Wolf-Rayet star instead of blue supergiant, and the central engine of this ultra-long burst is a black hole. The implications of our results is discussed.

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Jochen Greiner, last update: 17-May-2016 [Disclaimer]