Gamma-ray Burst 100621A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 21 Jun 10 03:04:00 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     425151,   Seg_Num: 0
GRB_RA:          315.308d {+21h 01m 14s} (J2000),
                 315.493d {+21h 01m 58s} (current),
                 314.422d {+20h 57m 41s} (1950)
GRB_DEC:         -51.086d {-51d 05' 10"} (J2000),
                 -51.045d {-51d 02' 41"} (current),
                 -51.283d {-51d 16' 57"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       6639 [cnts]    Image_Peak=813 [image_cnts]
TRIGGER_DUR:     1.024 [sec]
TRIGGER_INDEX:   146     E_range: 25-100 keV
BKG_INTEN:       24527 [cnts]
BKG_TIME:        10994.08 SOD {03:03:14.08} UT
BKG_DUR:         8 [sec]
GRB_DATE:        15368 TJD;   172 DOY;   10/06/21
GRB_TIME:        11012.84 SOD {03:03:32.84} UT
GRB_PHI:         -145.24 [deg]
GRB_THETA:        17.05 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     58.75 [sigma]
IMAGE_SIGNIF:    18.67 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +2  +6  +0  +0 +71  +0
SUN_POSTN:        89.63d {+05h 58m 31s}  +23.44d {+23d 26' 13"}
SUN_DIST:        135.32 [deg]   Sun_angle= 8.9 [hr] (West of Sun)
MOON_POSTN:      200.99d {+13h 23m 57s}  -14.40d {-14d 23' 57"}
MOON_DIST:        93.39 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      347.46,-40.90 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      301.99,-32.56 [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 = 318.73,20.52 [deg].

GCN NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Mon 21 Jun 10 03:04:52 UT
NOTICE_TYPE:    INTEGRAL SPI ACS Trigger
TRIGGER_NUM:    6028,   Sub_Num: 0
GRB_INTEN:      9.02 [sigma]
GRB_TIME:       11006.68 SOD {03:03:26.68} UT
GRB_DATE:       15368 TJD;   172 DOY;   10/06/21
COMMENTS:       INTEGRAL SPI_ACS GRB Trigger.
COMMENTS:
COMMENTS:       NOTE: This SPIACS event is temporally(6.0<100sec) coincident with the SWIFT_BAT event (trignum=425151).
COMMENTS:
COMMENTS:       The SPIACS lightcurve can be found at:
COMMENTS:
ftp://isdcarc.unige.ch/arc/FTP/ibas/spiacs/2010-06/2010-06-21T03-03-26.5148-13288-00007-0.lc

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 21 Jun 10 03:05:15 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     425151,   Seg_Num: 0
GRB_RA:          315.3004d {+21h 01m 12.09s} (J2000),
                 315.4852d {+21h 01m 56.45s} (current),
                 314.4144d {+20h 57m 39.45s} (1950)
GRB_DEC:         -51.1063d {-51d 06' 22.6"} (J2000),
                 -51.0648d {-51d 03' 53.3"} (current),
                 -51.3027d {-51d 18' 09.6"} (1950)
GRB_ERROR:       5.0 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       7.49e-08 [erg/cm2/sec]
GRB_SIGNIF:      10.77 [sigma]
IMG_START_DATE:  15368 TJD;   172 DOY;   10/06/21
IMG_START_TIME:  11088.83 SOD {03:04:48.83} UT,   76.0 [sec] since BAT Trigger Time
TAM[0-3]:        327.65 237.26 261.43 243.64
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:        89.63d {+05h 58m 31s}  +23.44d {+23d 26' 13"}
SUN_DIST:        135.31 [deg]   Sun_angle= 8.9 [hr] (West of Sun)
MOON_POSTN:      201.00d {+13h 24m 00s}  -14.40d {-14d 24' 12"}
MOON_DIST:        93.37 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      347.44,-40.89 [deg] galactic lon,lat of the burst
ECL_COORDS:      301.98,-32.58 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 1.22 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 21 Jun 10 03:05:25 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     425151,   Seg_Num: 0
GRB_RA:          315.3004d {+21h 01m 12.0s} (J2000),
                 315.4852d {+21h 01m 56.4s} (current),
                 314.4144d {+20h 57m 39.4s} (1950)
GRB_DEC:         -51.1063d {-51d 06' 22.6"} (J2000),
                 -51.0648d {-51d 03' 53.3"} (current),
                 -51.3027d {-51d 18' 09.6"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       116 [cnts]
IMG_START_DATE:  15368 TJD;   172 DOY;   10/06/21
IMG_START_TIME:  11088.83 SOD {03:04:48.83} UT,   76.0 [sec] since BAT Trigger Time
CENTROID_X:      307.74,  raw= 308  [pixels]
CENTROID_Y:      262.10,  raw= 262  [pixels]
ROLL:            110.75 [deg]
GAIN:            1
MODE:            2, Short Image mode
WAVEFORM:        134
EXPO_TIME:       0.10 [sec]
GRB_POS_XRT_Y:   -84.62
GRB_POS_XRT_Z:   12.83
IMAGE_URL:       sw00425151000msxps_rw.img
SUN_POSTN:        89.63d {+05h 58m 31s}  +23.44d {+23d 26' 13"}
SUN_DIST:        135.31 [deg]   Sun_angle= 8.9 [hr] (West of Sun)
MOON_POSTN:      201.00d {+13h 24m 00s}  -14.40d {-14d 24' 14"}
MOON_DIST:        93.37 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      347.44,-40.89 [deg] galactic lon,lat of the burst
ECL_COORDS:      301.98,-32.58 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 21 Jun 10 03:05:31 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     425151,   Seg_Num: 0
GRB_RA:          315.3004d {+21h 01m 12.0s} (J2000),
                 315.4852d {+21h 01m 56.4s} (current),
                 314.4144d {+20h 57m 39.4s} (1950)
GRB_DEC:         -51.1063d {-51d 06' 22.6"} (J2000),
                 -51.0648d {-51d 03' 53.3"} (current),
                 -51.3027d {-51d 18' 09.6"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       116 [cnts]
IMG_START_DATE:  15368 TJD;   172 DOY;   10/06/21
IMG_START_TIME:  11088.83 SOD {03:04:48.83} UT,   76.0 [sec] since BAT Trigger Time
CENTROID_X:      307.74,  raw= 308  [pixels]
CENTROID_Y:      262.10,  raw= 262  [pixels]
ROLL:            110.75 [deg]
GAIN:            1
MODE:            2, Short Image mode
WAVEFORM:        134
EXPO_TIME:       0.10 [sec]
GRB_POS_XRT_Y:   -84.62
GRB_POS_XRT_Z:   12.83
IMAGE_URL:       sw00425151000msxps_rw.img
SUN_POSTN:        89.63d {+05h 58m 31s}  +23.44d {+23d 26' 13"}
SUN_DIST:        135.31 [deg]   Sun_angle= 8.9 [hr] (West of Sun)
MOON_POSTN:      201.00d {+13h 24m 00s}  -14.40d {-14d 24' 16"}
MOON_DIST:        93.37 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      347.44,-40.89 [deg] galactic lon,lat of the burst
ECL_COORDS:      301.98,-32.58 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 21 Jun 10 03:07:03 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     425151,   Seg_Num: 0
GRB_RA:          315.308d {+21h 01m 14s} (J2000),
                 315.493d {+21h 01m 58s} (current),
                 314.422d {+20h 57m 41s} (1950)
GRB_DEC:         -51.086d {-51d 05' 10"} (J2000),
                 -51.045d {-51d 02' 41"} (current),
                 -51.283d {-51d 16' 57"} (1950)
GRB_DATE:        15368 TJD;   172 DOY;   10/06/21
GRB_TIME:        11012.84 SOD {03:03:32.84} UT
TRIGGER_INDEX:   146
GRB_PHI:         -145.24 [deg]
GRB_THETA:        17.05 [deg]
DELTA_TIME:      45.00 [sec]
TRIGGER_DUR:     1.024 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     58.75 [sigma]
IMAGE_SIGNIF:    18.67 [sigma]
LC_URL:          sw00425151000msb.lc
SUN_POSTN:        89.63d {+05h 58m 31s}  +23.44d {+23d 26' 13"}
SUN_DIST:        135.32 [deg]   Sun_angle= 8.9 [hr] (West of Sun)
MOON_POSTN:      201.02d {+13h 24m 04s}  -14.41d {-14d 24' 34"}
MOON_DIST:        93.37 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      347.46,-40.90 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      301.99,-32.56 [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 = 318.73,20.52 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 21 Jun 10 03:07:50 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     425151,   Seg_Num: 0
POINT_RA:        315.322d {+21h 01m 17s} (J2000)
POINT_DEC:       -51.085d {-51d 05' 05"} (J2000)
POINT_ROLL:      110.744d
IMG_START_DATE:  15368 TJD;   172 DOY;   10/06/21
IMG_START_TIME:  11097.52 SOD {03:04:57.52} UT,   84.7 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.014
N_STARS:         125
X_OFFSET:        448 [pixels]
Y_OFFSET:        600 [pixels]
X_MAX:           1407 [pixels]
Y_MAX:           1559 [pixels]
DET_THRESH:      12
PHOTO_THRESH:    6
SL_URL:          sw00425151000msufc0084.fits
SUN_POSTN:        89.63d {+05h 58m 32s}  +23.44d {+23d 26' 13"}
SUN_DIST:        135.31 [deg]   Sun_angle= 8.9 [hr] (West of Sun)
MOON_POSTN:      201.02d {+13h 24m 06s}  -14.41d {-14d 24' 43"}
MOON_DIST:        93.37 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      347.46,-40.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      302.00,-32.56 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 21 Jun 10 03:07:50 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     425151,   Seg_Num: 0
POINT_RA:        315.322d {+21h 01m 17s} (J2000)
POINT_DEC:       -51.085d {-51d 05' 05"} (J2000)
POINT_ROLL:      110.744d
IMG_START_DATE:  15368 TJD;   172 DOY;   10/06/21
IMG_START_TIME:  11097.52 SOD {03:04:57.52} UT,   84.7 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.014
N_STARS:         125
X_OFFSET:        448 [pixels]
Y_OFFSET:        600 [pixels]
X_MAX:           1407 [pixels]
Y_MAX:           1559 [pixels]
DET_THRESH:      12
PHOTO_THRESH:    6
SL_URL:          sw00425151000msufc0084.fits
SUN_POSTN:        89.63d {+05h 58m 32s}  +23.44d {+23d 26' 13"}
SUN_DIST:        135.31 [deg]   Sun_angle= 8.9 [hr] (West of Sun)
MOON_POSTN:      201.02d {+13h 24m 06s}  -14.41d {-14d 24' 43"}
MOON_DIST:        93.37 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      347.46,-40.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      302.00,-32.56 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 21 Jun 10 03:08:17 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     425151,   Seg_Num: 0
POINT_RA:        315.322d {+21h 01m 17s} (J2000)
POINT_DEC:       -51.085d {-51d 05' 05"} (J2000)
POINT_ROLL:      110.744d
IMG_START_DATE:  15368 TJD;   172 DOY;   10/06/21
IMG_START_TIME:  11097.52 SOD {03:04:57.52} UT,   84.7 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.014
N_STARS:         125
X_OFFSET:        448 [pixels]
Y_OFFSET:        600 [pixels]
X_MAX:           1407 [pixels]
Y_MAX:           1559 [pixels]
DET_THRESH:      12
PHOTO_THRESH:    6
SL_URL:          sw00425151000msufc0084.fits
SUN_POSTN:        89.63d {+05h 58m 32s}  +23.44d {+23d 26' 13"}
SUN_DIST:        135.31 [deg]   Sun_angle= 8.9 [hr] (West of Sun)
MOON_POSTN:      201.03d {+13h 24m 07s}  -14.41d {-14d 24' 49"}
MOON_DIST:        93.37 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      347.46,-40.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      302.00,-32.56 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 21 Jun 10 03:09:10 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     425151,   Seg_Num: 0
POINT_RA:        315.322d {+21h 01m 17s} (J2000)
POINT_DEC:       -51.085d {-51d 05' 05"} (J2000)
ROLL:            110.744d
IMG_START_DATE:  15368 TJD;   172 DOY;   10/06/21
IMG_START_TIME:  11097.52 SOD {03:04:57.52} UT,   84.7 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     298782303
X_OFFSET:        856 [pixels]
Y_OFFSET:        1035 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1016
Y_GRB_POS:       1195
BINNING_INDEX:   1
IM_URL:          sw00425151000msuni0090.fits
SUN_POSTN:        89.63d {+05h 58m 32s}  +23.44d {+23d 26' 13"}
SUN_DIST:        135.31 [deg]   Sun_angle= 8.9 [hr] (West of Sun)
MOON_POSTN:      201.04d {+13h 24m 08s}  -14.42d {-14d 25' 00"}
MOON_DIST:        93.36 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      347.46,-40.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      302.00,-32.56 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 21 Jun 10 03:09:28 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     425151,   Seg_Num: 0
POINT_RA:        315.322d {+21h 01m 17s} (J2000)
POINT_DEC:       -51.085d {-51d 05' 05"} (J2000)
ROLL:            110.744d
IMG_START_DATE:  15368 TJD;   172 DOY;   10/06/21
IMG_START_TIME:  11097.52 SOD {03:04:57.52} UT,   84.7 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     298782303
X_OFFSET:        856 [pixels]
Y_OFFSET:        1035 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1016
Y_GRB_POS:       1195
BINNING_INDEX:   1
IM_URL:          sw00425151000msuni0090.fits
SUN_POSTN:        89.63d {+05h 58m 32s}  +23.44d {+23d 26' 13"}
SUN_DIST:        135.31 [deg]   Sun_angle= 8.9 [hr] (West of Sun)
MOON_POSTN:      201.04d {+13h 24m 09s}  -14.42d {-14d 25' 03"}
MOON_DIST:        93.36 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      347.46,-40.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      302.00,-32.56 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 21 Jun 10 03:15:35 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     425151,   Seg_Num: 0
POINT_RA:        315.319d {+21h 01m 17s} (J2000)
POINT_DEC:       -51.086d {-51d 05' 08"} (J2000)
POINT_ROLL:      110.750d
IMG_START_DATE:  15368 TJD;   172 DOY;   10/06/21
IMG_START_TIME:  11309.52 SOD {03:08:29.52} UT,   296.7 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.602
N_STARS:         133
X_OFFSET:        536 [pixels]
Y_OFFSET:        715 [pixels]
X_MAX:           1495 [pixels]
Y_MAX:           1674 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw00425151000msufc0296.fits
SUN_POSTN:        89.64d {+05h 58m 33s}  +23.44d {+23d 26' 13"}
SUN_DIST:        135.31 [deg]   Sun_angle= 8.9 [hr] (West of Sun)
MOON_POSTN:      201.09d {+13h 24m 23s}  -14.44d {-14d 26' 17"}
MOON_DIST:        93.31 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      347.46,-40.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      302.00,-32.56 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 21 Jun 10 03:15:53 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     425151,   Seg_Num: 0
POINT_RA:        315.319d {+21h 01m 17s} (J2000)
POINT_DEC:       -51.086d {-51d 05' 08"} (J2000)
POINT_ROLL:      110.750d
IMG_START_DATE:  15368 TJD;   172 DOY;   10/06/21
IMG_START_TIME:  11309.52 SOD {03:08:29.52} UT,   296.7 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.602
N_STARS:         133
X_OFFSET:        536 [pixels]
Y_OFFSET:        715 [pixels]
X_MAX:           1495 [pixels]
Y_MAX:           1674 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw00425151000msufc0296.fits
SUN_POSTN:        89.64d {+05h 58m 33s}  +23.44d {+23d 26' 13"}
SUN_DIST:        135.31 [deg]   Sun_angle= 8.9 [hr] (West of Sun)
MOON_POSTN:      201.10d {+13h 24m 23s}  -14.44d {-14d 26' 20"}
MOON_DIST:        93.31 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      347.46,-40.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      302.00,-32.56 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 21 Jun 10 03:16:41 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     425151,   Seg_Num: 0
POINT_RA:        315.319d {+21h 01m 17s} (J2000)
POINT_DEC:       -51.086d {-51d 05' 08"} (J2000)
ROLL:            110.750d
IMG_START_DATE:  15368 TJD;   172 DOY;   10/06/21
IMG_START_TIME:  11309.52 SOD {03:08:29.52} UT,   296.7 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     298782515
X_OFFSET:        856 [pixels]
Y_OFFSET:        1035 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1016
Y_GRB_POS:       1195
BINNING_INDEX:   1
IM_URL:          sw00425151000msuni0302.fits
SUN_POSTN:        89.64d {+05h 58m 33s}  +23.44d {+23d 26' 13"}
SUN_DIST:        135.31 [deg]   Sun_angle= 8.9 [hr] (West of Sun)
MOON_POSTN:      201.10d {+13h 24m 25s}  -14.44d {-14d 26' 30"}
MOON_DIST:        93.30 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      347.46,-40.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      302.00,-32.56 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 21 Jun 10 03:16:53 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     425151,   Seg_Num: 0
POINT_RA:        315.319d {+21h 01m 17s} (J2000)
POINT_DEC:       -51.086d {-51d 05' 08"} (J2000)
ROLL:            110.750d
IMG_START_DATE:  15368 TJD;   172 DOY;   10/06/21
IMG_START_TIME:  11309.52 SOD {03:08:29.52} UT,   296.7 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     298782515
X_OFFSET:        856 [pixels]
Y_OFFSET:        1035 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1016
Y_GRB_POS:       1195
BINNING_INDEX:   1
IM_URL:          sw00425151000msuni0302.fits
SUN_POSTN:        89.64d {+05h 58m 33s}  +23.44d {+23d 26' 13"}
SUN_DIST:        135.31 [deg]   Sun_angle= 8.9 [hr] (West of Sun)
MOON_POSTN:      201.11d {+13h 24m 25s}  -14.44d {-14d 26' 32"}
MOON_DIST:        93.30 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      347.46,-40.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      302.00,-32.56 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN Circular #10870
T. N. Ukwatta (GSFC/GWU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), V. D'Elia (ASDC), N. Gehrels (NASA/GSFC), J. M. Gelbord (PSU), S. T. Holland (CRESST/USRA/GSFC), C. B. Markwardt (CRESST/GSFC/UMD), M. H. Siegel (PSU), M. Stamatikos (OSU/NASA/GSFC), M. A. Stark (PSU) and G. Stratta (ASDC) report on behalf of the Swift Team:
At 03:03:32 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 100621A (trigger=425151). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 315.308, -51.086 which is
```
   RA(J2000) = 21h 01m 14s
   Dec(J2000) = -51d 05' 10"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a triple-peaked structure with a duration of about 100 sec. The peak count rate was ~25,000 counts/sec (15-350 keV), at ~25 sec after the trigger.
The XRT began observing the field at 03:04:48.8 UT, 76.0 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 315.3004, -51.1063 which is equivalent to:
```
   RA(J2000)  = 21h 01m 12.09s
   Dec(J2000) = -51d 06' 22.6"
```
with an uncertainty of 5.0 arcseconds (radius, 90% containment). This location is 73 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy.
The initial flux in the 0.1 s image was 7.49e-08 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 84 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 0.03.
Burst Advocate for this burst is T. N. Ukwatta (tilan.ukwatta AT gmail.com). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.)

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 21 Jun 10 03:23:13 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     425151,   Seg_Num: 0
POINT_RA:        315.319d {+21h 01m 17s} (J2000)
POINT_DEC:       -51.086d {-51d 05' 08"} (J2000)
POINT_ROLL:      110.750d
IMG_START_DATE:  15368 TJD;   172 DOY;   10/06/21
IMG_START_TIME:  11888.63 SOD {03:18:08.63} UT,   875.8 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.064
N_STARS:         190
X_OFFSET:        296 [pixels]
Y_OFFSET:        475 [pixels]
X_MAX:           1735 [pixels]
Y_MAX:           1914 [pixels]
DET_THRESH:      12
PHOTO_THRESH:    6
SL_URL:          sw00425151000msufc0875.fits
SUN_POSTN:        89.64d {+05h 58m 34s}  +23.44d {+23d 26' 13"}
SUN_DIST:        135.32 [deg]   Sun_angle= 8.9 [hr] (West of Sun)
MOON_POSTN:      201.16d {+13h 24m 39s}  -14.46d {-14d 27' 48"}
MOON_DIST:        93.25 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      347.46,-40.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      302.00,-32.56 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 21 Jun 10 03:23:29 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     425151,   Seg_Num: 0
POINT_RA:        315.319d {+21h 01m 17s} (J2000)
POINT_DEC:       -51.086d {-51d 05' 08"} (J2000)
POINT_ROLL:      110.750d
IMG_START_DATE:  15368 TJD;   172 DOY;   10/06/21
IMG_START_TIME:  11888.63 SOD {03:18:08.63} UT,   875.8 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.064
N_STARS:         190
X_OFFSET:        296 [pixels]
Y_OFFSET:        475 [pixels]
X_MAX:           1735 [pixels]
Y_MAX:           1914 [pixels]
DET_THRESH:      12
PHOTO_THRESH:    6
SL_URL:          sw00425151000msufc0875.fits
SUN_POSTN:        89.64d {+05h 58m 34s}  +23.44d {+23d 26' 13"}
SUN_DIST:        135.32 [deg]   Sun_angle= 8.9 [hr] (West of Sun)
MOON_POSTN:      201.17d {+13h 24m 40s}  -14.46d {-14d 27' 52"}
MOON_DIST:        93.25 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      347.46,-40.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      302.00,-32.56 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 21 Jun 10 03:24:35 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     425151,   Seg_Num: 0
POINT_RA:        315.319d {+21h 01m 17s} (J2000)
POINT_DEC:       -51.086d {-51d 05' 08"} (J2000)
ROLL:            110.750d
IMG_START_DATE:  15368 TJD;   172 DOY;   10/06/21
IMG_START_TIME:  11888.63 SOD {03:18:08.63} UT,   875.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     298783094
X_OFFSET:        855 [pixels]
Y_OFFSET:        1034 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1015
Y_GRB_POS:       1194
BINNING_INDEX:   1
IM_URL:          sw00425151000msuni0881.fits
SUN_POSTN:        89.64d {+05h 58m 34s}  +23.44d {+23d 26' 13"}
SUN_DIST:        135.32 [deg]   Sun_angle= 8.9 [hr] (West of Sun)
MOON_POSTN:      201.18d {+13h 24m 42s}  -14.47d {-14d 28' 05"}
MOON_DIST:        93.24 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      347.46,-40.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      302.00,-32.56 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 21 Jun 10 03:24:41 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     425151,   Seg_Num: 0
GRB_RA:          315.3050d {+21h 01m 13.20s} (J2000),
                 315.4898d {+21h 01m 57.55s} (current),
                 314.4190d {+20h 57m 40.56s} (1950)
GRB_DEC:         -51.1062d {-51d 06' 22.3"} (J2000),
                 -51.0647d {-51d 03' 52.9"} (current),
                 -51.3026d {-51d 18' 09.3"} (1950)
GRB_ERROR:       2.1 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  15368 TJD;   172 DOY;   10/06/21
IMG_START_TIME:  11420.00 SOD {03:10:20.00} UT,   407.2 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:        89.64d {+05h 58m 34s}  +23.44d {+23d 26' 13"}
SUN_DIST:        135.32 [deg]   Sun_angle= 8.9 [hr] (West of Sun)
MOON_POSTN:      201.18d {+13h 24m 42s}  -14.47d {-14d 28' 06"}
MOON_DIST:        93.22 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      347.44,-40.90 [deg] galactic lon,lat of the burst
ECL_COORDS:      301.98,-32.58 [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:     Mon 21 Jun 10 03:24:53 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     425151,   Seg_Num: 0
POINT_RA:        315.319d {+21h 01m 17s} (J2000)
POINT_DEC:       -51.086d {-51d 05' 08"} (J2000)
ROLL:            110.750d
IMG_START_DATE:  15368 TJD;   172 DOY;   10/06/21
IMG_START_TIME:  11888.63 SOD {03:18:08.63} UT,   875.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     298783094
X_OFFSET:        855 [pixels]
Y_OFFSET:        1034 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1015
Y_GRB_POS:       1194
BINNING_INDEX:   1
IM_URL:          sw00425151000msuni0881.fits
SUN_POSTN:        89.64d {+05h 58m 35s}  +23.44d {+23d 26' 13"}
SUN_DIST:        135.32 [deg]   Sun_angle= 8.9 [hr] (West of Sun)
MOON_POSTN:      201.18d {+13h 24m 43s}  -14.47d {-14d 28' 08"}
MOON_DIST:        93.24 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      347.46,-40.91 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      302.00,-32.56 [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 #10871
S. B. Pandey (U Mich), W. Rujopakarn (Steward), T. Guver (U Arizona), W. Zheng (U Mich), report on behalf of the ROTSE collaboration:
ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia, responded to GRB 100621A (Swift trigger 425151; Ukwatta T. N., GCN 10870), producing images beginning 5.0 s after the GCN notice time. An automated response took the first image at 03:04:05.0 UT, 32.2 s after the burst, and during the gamma-ray emission, under fair conditions. We took 10 5-sec, 10 20-sec and 10 60-sec exposures. These unfiltered images are calibrated relative to USNO A2.0 (R). Imaging is on going.
Comparison to the DSS (second epoch) reveals no new sources within the 3-sigma Swift/BAT error circle or the XRT error circle; the field is not crowded. Individual images have limiting magnitudes ranging from 16.1-17.3; we set the following specific limits.
```
start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd?
--------------------------------------------------------------------
03:04:05.0 03:04:10.0 5 16.1 32.2 N
03:05:30.0 03:09:13.0 200 18.4 232.2 Y
```
GCN Circular #10872
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Using 0 s of promptly downlinked XRT event data for GRB 100621A, we find an enhanced XRT position of the afterglow: RA, Dec: 315.3052, -51.1060 which is equivalent to:
```
   RA (J2000)  = 21 01 13.24
   Dec (J2000) = -51 06 21.7
```
with an uncertainty of 2.0 arc sec (radius, 90% confidence). Analysis of the promptly available data is online at http://www.swift.ac.uk/sper/425151.
Position enhancement is is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177).
This circular is an official product of the Swift-XRT team.
GCN Circular #10873
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team.
Using 3262 s of XRT Photon Counting mode data and 4 UVOT images for GRB 100621A, 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 = 315.30466, -51.10624 which is equivalent to:
```
RA (J2000): 21h 01m 13.12s
Dec (J2000): -51d 06' 22.5"
```
with an uncertainty of 1.7 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177).
This circular was automatically generated, and is an official product of the Swift-XRT team.
GCN Circular #10874
Adria Updike (Clemson Univ.), Ana Nicuesa (Tautenburg Obs.), Marco Nardini, Thomas Kruehler and Jochen Greiner (all MPE Garching) report on behalf of the GROND team:
We observed the field of GRB 100621A (Swift trigger 425151; Ukwatta et al., GCN #10870) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPI/ESO telescope at La Silla Observatory (Chile). Observations started at 03:07 UT on June 21st, 4 minutes after the GRB trigger, and continued for 3 hours. They were performed at an average seeing of 1.5" under clear sky conditions.
In stacked images of 6 min total integration time in g'r'i'z' and 8 min in JHK, centered at 03:20 UT, we detect a bright, uncatalogued NIR source within the Swift/XRT error circle (Evans et al. GCN #10872) at the following coordinates:
```
RA (2000.0)  =  21h 01m 13.08s
DEC (2000.0) = -51d 06' 22.5"
```
with an error of +-0.3". This coincides with the enhanced XRT position (Evans et al. 2010, GCN #10873).
In the first hour the source faded by about 1 mag in the JHK bands, thus we identify this object as the GRB afterglow of GRB 100621A.
Our preliminary photometry centered at 03:45 UT is (in AB magnitudes):
```
g' = 22.7+-0.4 	
r' = 21.6+-0.1
i' = 20.5+-0.1 	
z' = 19.7+-0.1
J  = 17.3+-0.1
H  = 16.3+-0.1, and
K  = 15.8+-0.1
```
These magnitudes were derived by calibrating the images against the GROND zeropoints and 2MASS field stars and are not corrected for the Galactic foreground extinction corresponding to a reddening of E_(B-V)= 0.03 in the direction of the burst (Schlegel et al. 1998).
We note that there are indications of this source in the DSS2 images. Also, there is no fading in the g' band, suggesting that this is the underlying host galaxy at a redshift smaller than about 3. The extremely red colour then is likely due to severe intrinsic dust extinction.
We encourage spectroscopic observations.
GCN Circular #10875
T. N. Ukwatta (GWU) S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), (i.e. the Swift-BAT team):
Using the data set from T-240 to T+962 sec from recent telemetry downlinks, we report further analysis of BAT GRB 100621A (trigger #425151) (Ukwatta, et al., GCN Circ. 10870). The BAT ground-calculated position is RA, Dec = 315.309, -51.102 deg, which is
```
   RA(J2000)  =  21h 01m 14.1s 
   Dec(J2000) = -51d 06' 08.8" 
```
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 97%.
The mask-weighted light curve shows three main overlapping peaks starting at ~T-8 sec, with the main peak at ~T+25 sec, and ending at ~T+220 sec. T90 (15-350 keV) is 63.6 +- 1.7 sec (estimated error including systematics).
The time-averaged spectrum from T-6 to T+204 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.90 +- 0.03. The fluence in the 15-150 keV band is 2.1 +- 0.0 x 10^-5 erg/cm2. The 1-sec peak photon flux measured from T+24.46 sec in the 15-150 keV band is 12.8 +- 0.3 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/425151/BA/
GCN Circular #10876
B. Milvang-Jensen (DARK/NBI), P. Goldoni (APC/Univ. Paris 7 and SAp/CEA), N. R. Tanvir, K. Wiersema (Univ. Leicester), D. Malesani (DARK/NBI), A. de Ugarte Postigo (INAF-OAB), V. D'Elia (INAF-OAR and ASDC), S. D. Vergani (GEPI/Obs. Paris and APC/Univ. Paris 7), J. P. U. Fynbo (DARK/NBI), L. Kaper (Univ. Amsterdam), J. Sollerman (Univ. Stockholm), on behalf of the X-shooter GRB collaboration, and A. Updike (Clemson Univ.), J. Greiner, T. Kruehler (MPE Garching), on behalf of the GROND team, report:
We observed the optical afterglow of GRB 100621A (Ukwatta et al., GCN 10870; Updike et al., GCN 10874) with the ESO VLT equipped with the X-shooter spectrograph. The afterglow was detected in the I-band acquisition image. Four spectra lasting 10 minutes each were obtained, covering the spectral range 3000-25000 AA, starting on 2010 June 21, at 10:09 UT (7.1 hr after the GRB); the observations were done during twilight. Preliminary inspection of the spectrum reveals emission features which we interpret as due to [O II] 3727, Hbeta and the [O III] doublet from the underlying host galaxy, at a common redshift z = 0.542. The [O II] line is very weak. This, together with the low redshift and the optically faint and red afterglow supports high extinction internal to the host (Updike et al., GCN 10874).
We caution that the data reduction was carried out using archival calibration files. We acknowledge a particularly helpful and attentive support from the ESO staff in Paranal: M. Olivares, T. Rivinius, C. Ledoux, C. Martayan, and the visiting astronomers: F. Ferraro, B. Lanzoni.
GCN Circular #10877
G. Stratta (ASDC), V. D'Elia (ASDC) and T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift-XRT team:
We have analysed 3.6 ks of XRT data for GRB 100621A (Ukwatta et al. GCN Circ. 10870), from 79 s to 7.0 ks after the BAT trigger. The data comprise 322 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN. Circ 10872).
The light curve can be modelled with a series of power-law decays. The initial decay index is alpha=3.41 (+0.11, -0.18). At T+153 s the decay steepens to an alpha of 4.34 (+0.20, -0.12) before breaking again at T+389 s to a final decay with index alpha=0.55 (+0.13, -0.07).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.73 (+0.07, -0.06). The best-fitting absorption column is 6.11 (+0.27, -0.26) x 10^21 cm^-2, in excess of the Galactic value of 2.9 x 10^20 cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a photon index of 2.15 (+0.17, -0.16) and a best-fitting absorption column of 6.6 (+1.0, -0.9) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 5.0 x 10^-11 (1.0 x 10^-10) erg cm^-2 count^-1.
If the light curve continues to decay with a power-law decay index of 0.55, the count rate at T+24 hours will be 0.23 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.1 x 10^-11 (2.4 x 10^-11) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00425151.
This circular is an official product of the Swift-XRT team.
GCN Circular #10878
S. R. Oates (MSSL-UCL) and T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 100621A 85s after the BAT trigger (Ukwatta et al., GCN 10870). We detect a source at the enhanced Swift XRT position (Evans et al. GCN 10873) and at the location of the GROND source (Updike et al. GCN 10874). This source is also observed in the DSS and observed to be constant during the first 7000s and is thus likely to be the host galaxy, which is also suggested by Updike et al. (GCN 10874).
The magnitudes and 3-sigma upper limits for the finding chart exposures (FC) and summed images for this possible host galaxy are:
```
Filter     T_start   T_stop   Exp(s)  Magnitude/3-sigma upper limit
-------------------------------------------------------------
white (FC)    85     234        147     20.87 +/- 0.35
white         576    7093       519     20.46 +/- 0.15
u     (FC)    297    546        246         > 20.18
u             700    6683       360         > 20.14
v             626    6067       391     19.49 +/- 0.31
b             552    6888       372     20.27 +/- 0.28
uvw1          1107   6478       352     19.64 +/- 0.25
uvm2          6073   6273       197         > 19.66
uvw2          5663   5863       197     19.60 +/- 0.28
-------------------------------------------------------------
```
The quoted upper limits have not been corrected for the expected Galactic extinction along the line of sight of E_(B-V) = 0.03 mag. All photometry is on the UVOT photometric system described in Poole et al. (2008, MNRAS, 383, 627).
GCN Circular #10880
D. Suzuki, F. Hayashi, S.Kobara, T. Sako, H. Naito, K. Omori (STE Lab, Nagoya Univ.) on behalf of the MOA Collaboration report:
We searched for an optical afterglow of GRB 100621A (GCN 10870, T. N. Ukwatta et al.) starting from 09:02 UT on 2010 June 21st (6 hours after the burst) with the MOA-II 1.8m telescope at Mt.John observatory in New Zealand. In a single image of a 300sec exposure with a wide-band Red filter (center wavelength ~ 750nm and FWHM ~ 250nm), we did not find any object within the error circle of the Swift XRT source position (GCN 10873). A 3 sigma upper limit is set in the I magnitude at 22.23 mag.
This photometry was done by using the DoPhot and calibrated against the USNO-B1.0 catalog stars, and not corrected for the Galactic extinction.
GCN Circular #10881
H. Naito, T. Sako, D. Suzuki, S. Kobara and K. Omori (Nagoya Univ.) on behalf of the MOA Collaboration, T. Nagayama, M. Kurita (Nagoya Univ.) and N. Oi (The Graduate University for Advanced Studies/NAOJ) on behalf of the IRSF Collabration report:
We searched for a NIR afterglow of GRB 100621A (Ukwatta et al., GCN 10870) starting from 04:02 to 04:51 UT on 2010 June 21 with the SIRIUS on the IRSF 1.4m telescope at SAAO in South Africa. In images of a 300 sec exposure with J, H and Ks filter, we detected an new source within the error circle of the enhanced Swift XRT position (Evans et al., GCN 10873) and at the location of the GROND source (Updike et al., GCN 10874) . The estimated magnitudes are the followings.
```
---------------------------------------------------------------
Mid time from   Total Exp.   J-mag*   H-mag*   K-mag*
trigger (min)     (s)
---------------------------------------------------------------
61.41                 300              16.56      15.22      14.18
67.61                 300              16.24      14.63      13.84
73.84                 300              15.27      13.78      12.63
80.14                 300              15.07      13.57      12.40
86.36                 300              14.93      13.45      12.23
92.56                 300              14.90      13.45      12.32
98.81                 300              14.93      13.47      12.34
105.0                 300              15.04      13.55      12.36
---------------------------------------------------------------
```
*Typical error is ~ 0.1 mag
This photometry was done by using the DoPhot and calibrated against the 2MASS catalog stars, and not corrected for the Galactic extinction. The source was brightened up by >1mag during our observation period while the other field stars were reasonably stable.
GCN Circular #10882
S. Golenetskii, R.Aptekar, D. Frederiks, E. Mazets, V. Pal'shin, P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf of the Konus-Wind team, report:
The long GRB 100621A (Swift-BAT trigger=425151; Ukwatta et al., GCN 10870; Ukwatta et al., GCN 10875) triggered Konus-Wind at T0=11013.352s UT (03:03:33.352)
The burst light curve shows multiple overlapping peaks with a total duration of ~80 s. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB100621_T11013/
As observed by Konus-Wind the burst had a fluence of 3.6(+/-0.4)x10-5 erg/cm2, and a 256-ms peak flux measured from T0+26.880s of 1.70(+/-0.13)x10-6 erg/cm2/s (both in the 20 keV - 2 MeV energy range).
The time-integrated spectrum of the burst (from T0 to T0+73.984 s) is best fit in the 20 keV - 2 MeV range by the GRB (Band) model, for which: the low-energy photon index alpha = -1.70 (+/-0.13), the high energy photon index beta = -2.45 ( <-2.3 ), the peak energy Ep = 95(-13, +18)keV (chi2 = 65/57 dof).
The spectrum at the maximum count rate (measured from T0+24.832 to T0+33.024 s) is best fit in the 20 keV - 2 MeV range by the GRB (Band) model, for which: the low-energy photon index alpha = -1.15 (-0.2/+0.3), the high energy photon index beta = -2.8 (-0.7/+0.3), the peak energy Ep = 83(+/-9)keV (chi2 = 64/57 dof).
Assuming z=0.542 (Milvang-Jensen et al., GCN 10876) and a standard cosmology model with H_0 = 70 km/s/Mpc, Omega_M = 0.27, Omega_Lambda = 0.73, the isotropic energy release E_iso = 2.8(+/-0.3)x10^52 erg, the peak luminosity (L_iso)_max = (2.04+/-0.16)x10^51 erg/s.
All the quoted results are preliminary. All the quoted errors are at the 90% confidence level.
GCN Report 291.1
GCN_Report 291.1 has been posted: http://gcn.gsfc.nasa.gov/reports/report_291_1.pdf by T.N. Ukwatta at GSFC/GWU titled: "Final report on Swift Observations of GRB 100621A"
1304.5852 from 23 Apr 13
J. Greiner et al.: The unusual afterglow of the Gamma-Ray Burst 100621A
In order to constrain the broad-band spectral energy distribution of the afterglow of GRB 100621A, dedicated observations were performed in the optical/near-infrared with the 7-channel "Gamma-Ray Burst Optical and Near-infrared Detector" (GROND) at the 2.2m MPG/ESO telescope, in the sub-millimeter band with the large bolometer array LABOCA at APEX, and at radio frequencies with ATCA. Utilizing also Swift X-ray observations, we attempt an interpretation of the observational data within the fireball scenario. The afterglow of GRB 100621A shows a very complex temporal as well as spectral evolution. We identify three different emission components, the most spectacular one causing a sudden intensity jump about one hour after the prompt emission. The spectrum of this component is much steeper than the canonical afterglow. We interpret this component using the prescription of Vlasis et al. (2011) for a two-shell collision after the first shell has been decelerated by the circumburst medium. We use the fireball scenario to derive constraints on the microphysical parameters of the first shell. Long-term energy injection into a narrow jet seems to provide an adequate description. Another noteworthy result is the large ($A_V$ = 3.6 mag) line-of-sight host extinction of the afterglow in an otherwise extremely blue host galaxy.
1307.4517 from 18 Jul 13
Jin Jun Geng et al.: Delayed Energy Injection Model For Gamma-Ray Burst Afterglows
The shallow decay phase and flares in the afterglows of gamma-ray bursts (GRBs) is widely believed to be associated with the later activation of central engine. Some models of energy injection involve with a continuous energy flow since the GRB trigger time, such as the magnetic dipole radiation from a magnetar. However, in the scenario involving with a black hole accretion system, the energy flow from the fall-back accretion may be delayed for a fall-back time $\sim t_{\rm fb}$. Thus we propose a delayed energy injection model, the delayed energy would cause a notable rise to the Lorentz factor of the external shock, which will "generate" a bump in the multiple band afterglows. If the delayed time is very short, our model degenerates to the previous models. Our model can well explain the significant re-brightening in the optical and infrared light curves of GRB 081029 and GRB 100621A. A considerable fall-back mass is needed to provide the later energy, this indicates GRBs accompanied with fall-back material may be associated with a low energy supernova so that fraction of the envelope can be survived during eruption. The fall-back time can give meaningful information of the properties of GRB progenitor stars.
1407.8180 from 1 Aug 14
E R Stanway et al.: Radio Observations of GRB Host Galaxies
We present 5.5 and 9.0 GHz observations of a sample of seventeen GRB host galaxies at z = 0.5-1.4, using the radio continuum to explore their star formation properties in the context of the small but growing sample of galaxies with similar observations. Four sources are detected, one of those (GRB 100418A) likely due to lingering afterglow emission. We suggest that the previously-reported radio afterglow of GRB 100621A may instead be due to host galaxy flux. We see no strong evidence for redshift evolution in the typical star formation rate of GRB hosts, but note that the fraction of `dark' bursts with detections is higher than would be expected given constraints on the more typical long GRB population. We also determine the average radio-derived star formation rates of core collapse supernovae at comparable redshift, and show that these are still well below the limits obtained for GRB hosts, and show evidence for a rise in typical star formation rate with redshift in supernova hosts.
1606.08285 from 28 Jun 16
Jochen Greiner et al.: Probing dust-obscured star formation in the most massive Gamma-Ray Burst host galaxies
Due to their relation to massive stars, long-duration gamma-ray bursts (GRBs) allow pinpointing star formation in galaxies independently of redshift, dust obscuration, or galaxy mass/size, thus providing a unique tool to investigate the star-formation history over cosmic time. About half of the optical afterglows of long-duration GRBs are missed due to dust extinction, and are primarily located in the most massive GRB hosts. In order to understand this bias it is important to investigate the amount of obscured star-formation in these GRB host galaxies. Radio emission of galaxies correlates with star-formation, but does not suffer extinction as do the optical star-formation estimators. We selected 11 GRB host galaxies with either large stellar mass or large UV-/optical-based star-formation rates (SFRs) and obtained radio observations of these with the Australia Telescope Compact Array and the Karl Jansky Very Large Array. Despite intentionally selecting GRB hosts with expected high SFRs, we do not find any star-formation-related radio emission in any of our targets. Our upper limit for GRB 100621A implies that the earlier reported radio detection was due to afterglow emission. We do detect radio emission from the position of GRB 020819B, but argue that it is in large parts, if not all, due to afterglow contamination. Half of our sample has radio-derived SFR limits which are only a factor 2--3 above the optically measured SFRs. This supports other recent studies that the majority of star formation in GRB hosts is not obscured by dust.

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Jochen Greiner, last update: 28-Jun-2016 [Disclaimer]