Gamma-ray Burst 060813

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 13 Aug 06 22:50:39 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     224364,   Seg_Num: 0
GRB_RA:          111.868d {+07h 27m 28s} (J2000),
                 111.933d {+07h 27m 44s} (current),
                 111.375d {+07h 25m 30s} (1950)
GRB_DEC:         -29.851d {-29d 51' 01"} (J2000),
                 -29.864d {-29d 51' 50"} (current),
                 -29.748d {-29d 44' 51"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       1334 [cnts]    Image_Peak=83 [image_cnts]
TRIGGER_DUR:     0.256 [sec] 
TRIGGER_INDEX:   65     E_range: 25-100 keV
BKG_INTEN:       33317 [cnts]
BKG_TIME:        82206.62 SOD {22:50:06.62} UT
BKG_DUR:         8 [sec]
GRB_DATE:        13960 TJD;   225 DOY;   06/08/13
GRB_TIME:        82222.68 SOD {22:50:22.68} UT
GRB_PHI:         -118.48 [deg]
GRB_THETA:        34.25 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     11.13 [sigma]
IMAGE_SIGNIF:    7.17 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +2 +24  +0  +1 -58  +1 
SUN_POSTN:       143.43d {+09h 33m 43s}  +14.48d {+14d 29' 02"}
SUN_DIST:         53.74 [deg]   Sun_angle= 2.1 [hr] (West of Sun)
MOON_POSTN:       20.68d {+01h 22m 44s}  +11.15d {+11d 09' 02"}
MOON_DIST:        96.60 [deg]
MOON_ILLUM:      73 [%]
GAL_COORDS:      243.45, -6.09 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      120.87,-50.97 [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 = 199.72,5.23 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 13 Aug 06 22:55:08 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     224364,   Seg_Num: 0
GRB_RA:          111.868d {+07h 27m 28s} (J2000),
                 111.933d {+07h 27m 44s} (current),
                 111.375d {+07h 25m 30s} (1950)
GRB_DEC:         -29.851d {-29d 51' 01"} (J2000),
                 -29.864d {-29d 51' 50"} (current),
                 -29.748d {-29d 44' 51"} (1950)
GRB_DATE:        13960 TJD;   225 DOY;   06/08/13
GRB_TIME:        82222.68 SOD {22:50:22.68} UT
TRIGGER_INDEX:   65
GRB_PHI:         -118.48 [deg]
GRB_THETA:        34.25 [deg]
DELTA_TIME:      -5.00 [sec]
TRIGGER_DUR:     0.256 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     11.13 [sigma]
IMAGE_SIGNIF:    7.17 [sigma]
LC_URL:          sw00224364000msb.lc
SUN_POSTN:       143.43d {+09h 33m 43s}  +14.48d {+14d 28' 58"}
SUN_DIST:         53.74 [deg]   Sun_angle= 2.1 [hr] (West of Sun)
MOON_POSTN:       20.72d {+01h 22m 54s}  +11.17d {+11d 10' 14"}
MOON_DIST:        96.57 [deg]
MOON_ILLUM:      73 [%]
GAL_COORDS:      243.45, -6.09 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      120.87,-50.97 [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 = 199.72,5.23 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 13 Aug 06 22:55:36 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     224364,   Seg_Num: 0
POINT_RA:        111.873d {+07h 27m 30s} (J2000)
POINT_DEC:       -29.850d {-29d 50' 58"} (J2000)
POINT_ROLL:      38.925d
IMG_START_DATE:  13960 TJD;   225 DOY;   06/08/13
IMG_START_TIME:  82303.90 SOD {22:51:43.90} UT,   81.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.752
N_STARS:         190
X_OFFSET:        456 [pixels]
Y_OFFSET:        536 [pixels]
X_MAX:           1415 [pixels]
Y_MAX:           1495 [pixels]
DET_THRESH:      16
PHOTO_THRESH:    9
SL_URL:          sw00224364000msufc0081.fits
SUN_POSTN:       143.43d {+09h 33m 44s}  +14.48d {+14d 28' 58"}
SUN_DIST:         53.74 [deg]   Sun_angle= 2.1 [hr] (West of Sun)
MOON_POSTN:       20.73d {+01h 22m 55s}  +11.17d {+11d 10' 22"}
MOON_DIST:        96.57 [deg]
MOON_ILLUM:      73 [%]
GAL_COORDS:      243.45, -6.09 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      120.87,-50.97 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 13 Aug 06 22:52:24 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     224364,   Seg_Num: 0
GRB_RA:          111.8958d {+07h 27m 34.9s} (J2000),
                 111.9610d {+07h 27m 50.6s} (current),
                 111.4035d {+07h 25m 36.8s} (1950)
GRB_DEC:         -29.8485d {-29d 50' 54.6"} (J2000),
                 -29.8623d {-29d 51' 44.1"} (current),
                 -29.7458d {-29d 44' 44.8"} (1950)
GRB_ERROR:       5.8 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       6.54e-10 [erg/cm2/sec]
GRB_SIGNIF:      5.38 [sigma]
IMG_START_DATE:  13960 TJD;   225 DOY;   06/08/13
IMG_START_TIME:  82298.92 SOD {22:51:38.92} UT,   76.2 [sec] since BAT Trigger Time
TAM[0-3]:        327.63 237.16 261.26 243.27
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       143.43d {+09h 33m 43s}  +14.48d {+14d 29' 00"}
SUN_DIST:         53.73 [deg]   Sun_angle= 2.1 [hr] (West of Sun)
MOON_POSTN:       20.70d {+01h 22m 48s}  +11.16d {+11d 09' 30"}
MOON_DIST:        96.61 [deg]
MOON_ILLUM:      73 [%]
GAL_COORDS:      243.46, -6.07 [deg] galactic lon,lat of the burst
ECL_COORDS:      120.90,-50.96 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 13 Aug 06 22:58:20 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     224364,   Seg_Num: 0
POINT_RA:        111.872d {+07h 27m 29s} (J2000)
POINT_DEC:       -29.852d {-29d 51' 08"} (J2000)
ROLL:            38.926d
IMG_START_DATE:  13960 TJD;   225 DOY;   06/08/13
IMG_START_TIME:  82409.74 SOD {22:53:29.74} UT,   187.1 [sec] since BAT Trigger Time
FILTER:          4, UVM2
EXPOSURE_ID:     177202411
X_OFFSET:        945 [pixels]
Y_OFFSET:        905 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1105
Y_GRB_POS:       1065
BINNING_INDEX:   1
IM_URL:          sw00224364000msuni0187.fits
SUN_POSTN:       143.43d {+09h 33m 44s}  +14.48d {+14d 28' 56"}
SUN_DIST:         53.74 [deg]   Sun_angle= 2.1 [hr] (West of Sun)
MOON_POSTN:       20.75d {+01h 23m 01s}  +11.18d {+11d 11' 06"}
MOON_DIST:        96.56 [deg]
MOON_ILLUM:      73 [%]
GAL_COORDS:      243.45, -6.09 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      120.87,-50.97 [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:        If you have elected to receive attachments:  
COMMENTS:        The uvot_sky_image.img.gz file does not exist; skipping the attachment.  
COMMENTS:        The uvot_sources_image.fits.gz file does not exist; skipping the attachment.  
COMMENTS:        The uvot_catalog_image.fits.gz file does not exist; skipping the attachment.  
COMMENTS:        The uvot_field_image.ps.gz file does not exist; skipping the attachment.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 13 Aug 06 22:57:01 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     224364,   Seg_Num: 0
POINT_RA:        111.872d {+07h 27m 29s} (J2000)
POINT_DEC:       -29.852d {-29d 51' 08"} (J2000)
POINT_ROLL:      38.926d
IMG_START_DATE:  13960 TJD;   225 DOY;   06/08/13
IMG_START_TIME:  82409.74 SOD {22:53:29.74} UT,   187.1 [sec] since BAT Trigger Time
FILTER:          4, UVM2
BKG_MEAN:        0.084
N_STARS:         27
X_OFFSET:        625 [pixels]
Y_OFFSET:        585 [pixels]
X_MAX:           1584 [pixels]
Y_MAX:           1544 [pixels]
DET_THRESH:      4
PHOTO_THRESH:    2
SL_URL:          sw00224364000msufc0187.fits
SUN_POSTN:       143.43d {+09h 33m 44s}  +14.48d {+14d 28' 57"}
SUN_DIST:         53.74 [deg]   Sun_angle= 2.1 [hr] (West of Sun)
MOON_POSTN:       20.74d {+01h 22m 58s}  +11.18d {+11d 10' 45"}
MOON_DIST:        96.56 [deg]
MOON_ILLUM:      73 [%]
GAL_COORDS:      243.45, -6.09 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      120.87,-50.97 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 13 Aug 06 22:52:50 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     224364,   Seg_Num: 0
GRB_RA:          111.8958d {+07h 27m 34.9s} (J2000),
                 111.9610d {+07h 27m 50.6s} (current),
                 111.4035d {+07h 25m 36.8s} (1950)
GRB_DEC:         -29.8485d {-29d 50' 54.6"} (J2000),
                 -29.8623d {-29d 51' 44.1"} (current),
                 -29.7458d {-29d 44' 44.8"} (1950)
GRB_ERROR:       5.8 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       29 [cnts]
IMG_START_DATE:  13960 TJD;   225 DOY;   06/08/13
IMG_START_TIME:  82298.92 SOD {22:51:38.92} UT,   76.2 [sec] since BAT Trigger Time
CENTROID_X:      281.20,  raw= 281  [pixels]
CENTROID_Y:      276.21,  raw= 276  [pixels]
ROLL:            38.93 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -53.24
GRB_POS_XRT_Z:   -47.36
IMAGE_URL:       sw00224364000msxps_rw.img
SUN_POSTN:       143.43d {+09h 33m 43s}  +14.48d {+14d 29' 00"}
SUN_DIST:         53.73 [deg]   Sun_angle= 2.1 [hr] (West of Sun)
MOON_POSTN:       20.70d {+01h 22m 49s}  +11.16d {+11d 09' 37"}
MOON_DIST:        96.61 [deg]
MOON_ILLUM:      73 [%]
GAL_COORDS:      243.46, -6.07 [deg] galactic lon,lat of the burst
ECL_COORDS:      120.90,-50.96 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 13 Aug 06 22:52:25 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     224364,   Seg_Num: 0
GRB_RA:          111.8958d {+07h 27m 34.9s} (J2000),
                 111.9610d {+07h 27m 50.6s} (current),
                 111.4035d {+07h 25m 36.8s} (1950)
GRB_DEC:         -29.8485d {-29d 50' 54.6"} (J2000),
                 -29.8623d {-29d 51' 44.1"} (current),
                 -29.7458d {-29d 44' 44.8"} (1950)
GRB_ERROR:       5.8 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       29 [cnts]
IMG_START_DATE:  13960 TJD;   225 DOY;   06/08/13
IMG_START_TIME:  82298.92 SOD {22:51:38.92} UT,   76.2 [sec] since BAT Trigger Time
CENTROID_X:      281.20,  raw= 281  [pixels]
CENTROID_Y:      276.21,  raw= 276  [pixels]
ROLL:            38.93 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -53.24
GRB_POS_XRT_Z:   -47.36
IMAGE_URL:       sw00224364000msxps_rw.img
SUN_POSTN:       143.43d {+09h 33m 43s}  +14.48d {+14d 29' 00"}
SUN_DIST:         53.73 [deg]   Sun_angle= 2.1 [hr] (West of Sun)
MOON_POSTN:       20.70d {+01h 22m 48s}  +11.16d {+11d 09' 30"}
MOON_DIST:        96.61 [deg]
MOON_ILLUM:      73 [%]
GAL_COORDS:      243.46, -6.07 [deg] galactic lon,lat of the burst
ECL_COORDS:      120.90,-50.96 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 13 Aug 06 22:58:15 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     224364,   Seg_Num: 0
POINT_RA:        111.872d {+07h 27m 29s} (J2000)
POINT_DEC:       -29.852d {-29d 51' 08"} (J2000)
ROLL:            38.926d
IMG_START_DATE:  13960 TJD;   225 DOY;   06/08/13
IMG_START_TIME:  82409.74 SOD {22:53:29.74} UT,   187.1 [sec] since BAT Trigger Time
FILTER:          4, UVM2
EXPOSURE_ID:     177202411
X_OFFSET:        945 [pixels]
Y_OFFSET:        905 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1105
Y_GRB_POS:       1065
BINNING_INDEX:   1
IM_URL:          sw00224364000msuni0187.fits
SUN_POSTN:       143.43d {+09h 33m 44s}  +14.48d {+14d 28' 56"}
SUN_DIST:         53.74 [deg]   Sun_angle= 2.1 [hr] (West of Sun)
MOON_POSTN:       20.75d {+01h 23m 01s}  +11.18d {+11d 11' 05"}
MOON_DIST:        96.56 [deg]
MOON_ILLUM:      73 [%]
GAL_COORDS:      243.45, -6.09 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      120.87,-50.97 [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:     Sun 13 Aug 06 22:59:46 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     224364,   Seg_Num: 0
POINT_RA:        111.872d {+07h 27m 29s} (J2000)
POINT_DEC:       -29.852d {-29d 51' 08"} (J2000)
POINT_ROLL:      38.926d
IMG_START_DATE:  13960 TJD;   225 DOY;   06/08/13
IMG_START_TIME:  82409.74 SOD {22:53:29.74} UT,   187.1 [sec] since BAT Trigger Time
FILTER:          4, UVM2
BKG_MEAN:        0.084
N_STARS:         27
X_OFFSET:        625 [pixels]
Y_OFFSET:        585 [pixels]
X_MAX:           1584 [pixels]
Y_MAX:           1544 [pixels]
DET_THRESH:      4
PHOTO_THRESH:    2
SL_URL:          sw00224364000msufc0187.fits
SUN_POSTN:       143.43d {+09h 33m 44s}  +14.48d {+14d 28' 55"}
SUN_DIST:         53.74 [deg]   Sun_angle= 2.1 [hr] (West of Sun)
MOON_POSTN:       20.77d {+01h 23m 04s}  +11.19d {+11d 11' 29"}
MOON_DIST:        96.55 [deg]
MOON_ILLUM:      73 [%]
GAL_COORDS:      243.45, -6.09 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      120.87,-50.97 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 13 Aug 06 22:56:26 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     224364,   Seg_Num: 0
POINT_RA:        111.873d {+07h 27m 30s} (J2000)
POINT_DEC:       -29.850d {-29d 50' 58"} (J2000)
ROLL:            38.925d
IMG_START_DATE:  13960 TJD;   225 DOY;   06/08/13
IMG_START_TIME:  82303.90 SOD {22:51:43.90} UT,   81.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     177202305
X_OFFSET:        945 [pixels]
Y_OFFSET:        905 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1105
Y_GRB_POS:       1065
BINNING_INDEX:   1
IM_URL:          sw00224364000msuni0081.fits
SUN_POSTN:       143.43d {+09h 33m 44s}  +14.48d {+14d 28' 57"}
SUN_DIST:         53.74 [deg]   Sun_angle= 2.1 [hr] (West of Sun)
MOON_POSTN:       20.74d {+01h 22m 57s}  +11.18d {+11d 10' 35"}
MOON_DIST:        96.57 [deg]
MOON_ILLUM:      73 [%]
GAL_COORDS:      243.45, -6.09 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      120.87,-50.97 [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:     Sun 13 Aug 06 23:00:14 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     224364,   Seg_Num: 0
POINT_RA:        111.872d {+07h 27m 29s} (J2000)
POINT_DEC:       -29.852d {-29d 51' 08"} (J2000)
ROLL:            38.926d
IMG_START_DATE:  13960 TJD;   225 DOY;   06/08/13
IMG_START_TIME:  82409.74 SOD {22:53:29.74} UT,   187.1 [sec] since BAT Trigger Time
FILTER:          4, UVM2
EXPOSURE_ID:     177202411
X_OFFSET:        945 [pixels]
Y_OFFSET:        905 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1105
Y_GRB_POS:       1065
BINNING_INDEX:   1
IM_URL:          sw00224364000msuni0187.fits
SUN_POSTN:       143.43d {+09h 33m 44s}  +14.48d {+14d 28' 54"}
SUN_DIST:         53.74 [deg]   Sun_angle= 2.1 [hr] (West of Sun)
MOON_POSTN:       20.77d {+01h 23m 05s}  +11.19d {+11d 11' 37"}
MOON_DIST:        96.55 [deg]
MOON_ILLUM:      73 [%]
GAL_COORDS:      243.45, -6.09 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      120.87,-50.97 [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:        If you have elected to receive attachments:  
COMMENTS:        The uvot_catalog_image.fits.gz file does not exist; skipping the attachment.

GCN Circular #5442
A. Moretti (INAF-OAB), S. D. Barthelmy (GSFC), J. R. Cummings (NASA/UMD), C. Guidorzi (Univ Bicocca&INAF-OAB), C. B. Markwardt (GSFC/UMD), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), P. Romano (INAF-OAB) and D. E. Vanden Berk (PSU) report on behalf of the Swift Team:
At 22:50:22 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 060813 (trigger=224364). Swift slewed immediately to the burst. The BAT on-board calculated location is RA,Dec 111.868, -29.851 {07h 27m 28s, -29d 51' 01"} (J2000) with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a single, roughly square peak with a duration of about 10 sec. The peak count rate was ~10,000 counts/sec (15-350 keV), at ~7 sec after the trigger.
The XRT began observing the field at 22:51:38 UT, 76 seconds after the BAT trigger. XRT found a variable, uncatalogued X-ray source located at RA(J2000) = 07h 27m 34.9s, Dec(J2000) = -29d 50' 54.6", with an estimated uncertainty of 5.8 arcseconds (90% confidence radius). This location is 87 arcseconds from the BAT on-board position, within the BAT error circle. The initial flux in the 2.5s image was 6.5e-10 erg/cm2/s (0.2-10 keV).
UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm) filter starting 83 seconds after the BAT trigger. No 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 18.5 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. The field is fairly crowded. No correction has been made for the expected extinction corresponding to E(B-V) of 0.33.
GCN Circular #5443
J. Cummings (GSFC/UMBC), L. Barbier (GSFC), S. D. Barthelmy (GSFC), E. Fenimore (LANL), N. Gehrels (GSFC), D. Hullinger (BYU-Idaho), H. Krimm (GSFC/USRA), M. Koss (GSFC/UMD), C. Markwardt (GSFC/UMD), A. Moretti (INAF-OAB), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC) on behalf of the Swift-BAT team:
Using the data set from T-239 to T+543 sec from the recent telemetry downlink, we report further analysis of BAT GRB 060813 (trigger #224364) (Moretti, et al., GCN Circ. 5442). The BAT ground-calculated position is RA,Dec = 111.890, -29.844 deg {7h 27m 33.6s, -29d 50' 40.2"} (J2000) +- 0.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 39%.
The mask-weighted lightcurve shows a roughly square-shaped peak starting at T-1 sec and lasting until T+9 sec. It is then followed a softer component, roughly constant but weaker intensity, lasting out to ~T+30 sec. T90 (15-350 keV) is 14.9 +- 0.5 sec (estimated error including systematics).
The time-averaged spectrum from T-0.5 to T+27.8 is best fit by a power law with an exponential cutoff. This fit gives a photon index 1.00 +- 0.19, and a poorly-constrained Epeak of 176 +- 83 keV (chi squared 35.17 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 5.5 +- 0.1 x 10^-6 erg/cm2 and the 1-sec peak flux measured from T+3.59 sec in the 15-150 keV band is 9.0 +- 0.4 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.35 +- 0.04 (chi squared 45.73 for 57 d.o.f.). All the quoted errors are at the 90% confidence level.
GCN Circular #5444
A. Moretti (INAF-OAB), C. Guidorzi (Univ. Bicocca & INAF-OAB), P. Romano (INAF-OAB) report on behalf of the Swift-XRT team:
We have analysed the first 4 orbits of Swift-XRT data obtained for GRB 060813 (trigger number 224364). The data consist of 611 s in Windowed Timing (WT) mode, starting 76 seconds after the BAT trigger and 7 ks in Photon Counting (PC) mode. Using PC data we obtain a refined position of:
```
RA(J2000) =   07 27 35.36
Dec(J2000) = -29 50 54.2
```
with an estimated uncertainty radius of 3.5 arcsec (90% containment). This is at 27" from the refined BAT position (Cummings et al., GCN Circ. 5443).
The light-curve shows a shallow decay with alpha = 0.58+/- 0.05, in the first part up to a break at time=861+/-180 s. After the break data show a decline with alpha = 1.10+/- 0.05.
The spectrum formed from all the WT data before the light-curve break can be modelled with a power-law of photon index Gamma = 1.98 +/- 0.08, with an absorbing column of NH = (4.4 +/- 0.4)e21 cm^-2 marginally consistent with the Galactic value of 3.1e21 cm^-2. The spectrum formed from the PC data after the light-curve break is maginally consistent with the pre-break spectrum: it can be modelled with a power-law of photon index Gamma = 1.80 +/- 0.10, with an absorbing column of NH = (3.2 +/- 0.5)e21 cm^-2.
Assuming the light-curve continues to decay with alpha ~ 1.10, the count rate at 24 hours is predicted to be 0.023 count s^-1. This corresponds to an observed (unabsorbed) flux of 1.4e-12 (1.9e-12) erg cm^-2 s^-1.
This circular is an official product of the Swift-XRT team.
GCN Circular #5445
A. Cucchiara, P. Brown, A. Moretti report on behalf of the Swift/UVOT team:
The Swift UVOT began observing GRB 060813 (trigger #224364, A. Moretti et al., GCN Circ. 5442) 83 seconds after the BAT trigger. No optical afterglow is detected in the XRT refined error circle (A. Moretti et al., GCN Circ. 5444).
The 3-sigma limiting magnitudes for the finding chart and the coadded images for the UVOT filters are listed below:
```
Finding chart:

Filter        T_range (s)    Exposure (s)    3sigma UL
White         83-181         98              19.46

Coadded images:

Filter          T_range (s)      Exposure (s)   3sigma UL
WHITE           83-12239         1394           20.89
V               183-29590        1235           19.66
B               391-18023        1822           21.03
U               366-23807        2203           20.76
W1              343-23609        2200           20.82
M2              300-22702        1613           20.86
W2              419-28770        1279           20.93
```
T_range is calculated from the time of the burst. No correction has been made for the Galactic reddening of E(B-V) = 0.33 mag (Schlegel et al. 1998) along the line of sight to the burst.
GCN Circular #5446
S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, and T. Cline on behalf of the Konus-Wind team report:
The long GRB 060813 (Swift-BAT trigger #224364; Moretti et al., GCN 5442; Cummings et al., GCN 5443) triggered Konus-Wind at T0=82221.576 s UT (22:50:21.576).
As observed by Konus-Wind the burst shows a single pulse with a duration of ~6 s, followed by a weak soft tail seen up to T-T0 ~13 s. The burst fluence is (1.18 +/- 0.07)x10^-5 erg/cm2, and the 64-ms peak flux measured from T0+5.136 s (2.96 +/- 0.58)x10^-6 erg/cm2/s (both in the 20 keV - 1 MeV energy range).
The time-integrated spectrum of the burst (from T0 to T0+6.656 s; in the 20 keV - 1 MeV range) is well fitted (in the 20 keV - 1 MeV range) by GRBM (Band) model for which: the low-energy photon index is alpha = -0.53 (-0.14,+0.16), the high energy photon index beta = -2.65(-0.49, +0.26), the break energy E0 = 130(-23, +27) keV (chi2 = 58/47 dof). The peak energy Ep = 192(-18, +20) keV.
All the quoted errors are at the 90% confidence level.
GCN Circular #5452
A. Pelangeon & J-L. Atteia (LATT-OMP) report:
We have used the spectral parameters of GRB 060813 provided by Golenetskii et al. (GCNC 5446) to compute the spectral pseudo-redshift** of this burst detected by SWIFT-BAT (Moretti et al., GCNC 5442).
We find a pseudo-redshift pz= 2.38 +/- 0.40
This is a typical value for a GRB.
** cf. http://www.ast.obs-mip.fr/grb/pz
[GCN OPS NOTE(15aug06): This Circular was delayed by ~2 hrs due to problems at the GCN end.]
GCN Circular #5462
K.Yamaoka, S.Sugita (Aoyama Gakuin U.), M.Ohno, T.Takahashi, T.Asano, T.Uehara, Y.Fukazawa (Hiroshima U.), Y.Terada, T.Tamagawa, M.Suzuki (RIKEN), K.Abe, K.Onda, M.Suzuki, M.Tashiro (Saitama U.), S.Hong (Nihon U.) K.Nakazawa, T.Takahashi (ISAS/JAXA), T.Enoto, R.Miyawaki, K.Kokubun (Univ. of Tokyo) on behalf of the Suzaku HXD-II team report:
The bright, long burst, GRB 060813 (Swift-BAT trigger #224364; Morettim et al., GCN5442; Cummings et al. GCN 5443), triggered the Suzaku Wideband All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV at 22:50:24.295 (UT). The observed prompt emission exhibits a single-peaked lightcurve with a duration (T90) of 6.1 seconds. The fluence in 100 - 1000 keV was (1.0 +/- 0.1)X10^-6 erg/cm2. The 1-s peak flux was 5.6 +/- 0.2 photons/cm2/s in the same energy range.
Preliminary result shows that the time-averaged spectrum is well-fitted by a power law with an exponential cutoff having the following parameters: alpha = 0.93 +- 0.31, E0 = 229 (+82, -53) keV, and Epeak = 248 +- 20 keV. All the quoted errors are at statistical 90% confidence level, not included in the systematic errors.
Further detailed analyses are in progress.
GCN Circular #5463
A. Moretti (INAF-OAB), P. Romano (INAF-OAB), C. Guidorzi (Univ. Bicocca & INAF-OAB), D.N. Burrows (PSU), N. Gehrels (GSFC) report on behalf of the Swift-XRT team:
Based on the most recent downlinked data on GRB060813 (trigger number 224364) we find clear evidence of a break in the light curve at 48(+/-10) ks from the burst trigger (see the light curve at http://www.brera.inaf.it/~moretti/grbplot/xrt060813.gif) which could be a jet break. The light curve slope steepens from 1.20+/-0.10 to 2.50+/-0.30 . (errors are quoted at 90% confidence level). In order to convert the XRT count rate to absorbed (unabsorbed) flux the conversion factor is 6.1E-11 (8.1E-11).
Therefore we encourage optical data collection on this GRB, when possible.
This circular is an official product of the Swift-XRT team.
GCN Circular #5477
T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS), S. D. Barthelmy (GSFC), J. Cummings (GSFC/ORAU), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), A. Parsons (GSFC), J. Tueller (GSFC), L. Barbier (GSFC), E. Fenimore (LANL), D. Hullinger (BYU-Idaho), M. Koss (GSFC/UMD), C. Markwardt (GSFC/UMD), D. Palmer (LANL), M. Stamatikos (GSFC/ORAU), on behalf of the Swift-BAT team,
S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, and T. Cline on behalf of the Konus-Wind team,
M. Ohno, T. Takahashi, T. Asano, T. Uehara, Y. Fukazawa (Hiroshima U.), K. Yamaoka, S. Sugita (Aoyama Gakuin U.), Y. Terada, T. Tamagawa, M. Suzuki (RIKEN), K. Abe, K. Onda, Y. Urata, M. Suzuki, M. Tashiro (Saitama U.), S. Hong (Nihon U.), K. Nakazawa, T. Takahashi (ISAS/JAXA), T. Enoto, R. Miyawaki, K. Kokubun, K. Makishima (Univ. of Tokyo) on behalf of the Suzaku-WAM team,
report:
We performed the Swift/BAT, Konus-Wind, and Suzaku/WAM joint fit spectral analysis of GRB 060813 (Swift-BAT trigger #224364; Moretti, et al., GCN Circ. 5442). The time interval of the spectral data for each instrument is chosen as the same interval as the Konus-Wind time-averaged spectrum reported by Golenetskii et al. (GCN Circ. 5446). The energy ranges which we used in the joint spectral analysis are 14-150 keV, 20-1000 keV, and 100-1000 keV, for Swift/BAT, Konus-Wind and Suzaku/WAM respectively. The spectral data of three instruments are fitted with the spectral model multiplied by the constant factor to take into account the systematic uncertainties in the response matrices of each instrument.
The spectrum is well fitted with a power-law time exponential cutoff model (dN/dE ~ E^{alpha} * exp(-(2+alpha)*E/Epeak)). The constant factors of each instrument agree within 10%. No systematic residual from the best fit model is seen in the spectral data of each instrument. The best fit spectral parameters are: alpha = -0.83 +- 0.05 and Epeak = 240 (-10/+11) keV (chi2/dof = 135/125). Although there is no significant improvement in the fit, the best fit parameters in the Band function are: the low-energy photon index alpha = -0.79 +- 0.06, the high energy photon index beta = -2.71 (-0.70/+0.24) and Epeak = 230 (-14/+15) keV (chi2/dof = 133/124). The energy fluence in the 15-1000 keV band calculated by the Band function is 1.22 +- 0.05 x 10^-5 erg/cm2 (in case the constant factor of the Konus-Wind is fixed to 1). The spectral paramters in a power-law time exponential cutoff model for Swift/BAT and Suzaku/WAM were reported by Cummings et al. (GCN Circ. 5443) and by Yamaoka, et al. (GCN Circ. 5462). The Konus-Wind best fit spectral parameters for a power-law time exponential cutoff model are: alpha = -0.65 (-0.12, +0.11), Epeak = 214 (-15, +17) keV (chi2/dof = 81/59). Our joint fit spectral parameters in a power-law time exponential cutoff model are consistent within 90% confidence level with the spectral parameters derived by individual instruments. However, we do see a systematic difference in the spectral parameters in the Band function fit especially in the low energy photon index alpha. We are still working on the cross-calibration among three instruments.
All the quoted errors are at the 90% confidence level.

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Jochen Greiner, last update: 25-Aug-2006 [Disclaimer]