Gamma-ray Burst 060926

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 26 Sep 06 16:48:56 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     231231,   Seg_Num: 0
GRB_RA:          263.955d {+17h 35m 49s} (J2000),
                 264.033d {+17h 36m 08s} (current),
                 263.379d {+17h 33m 31s} (1950)
GRB_DEC:         +13.041d {+13d 02' 29"} (J2000),
                 +13.037d {+13d 02' 15"} (current),
                 +13.072d {+13d 04' 20"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       6155 [cnts]    Image_Peak=371 [image_cnts]
TRIGGER_DUR:     1.024 [sec] 
TRIGGER_INDEX:   137     E_range: 15-50 keV
BKG_INTEN:       38047 [cnts]
BKG_TIME:        60510.53 SOD {16:48:30.53} UT
BKG_DUR:         8 [sec]
GRB_DATE:        14004 TJD;   269 DOY;   06/09/26
GRB_TIME:        60521.85 SOD {16:48:41.85} UT
GRB_PHI:          98.06 [deg]
GRB_THETA:         9.10 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     17.32 [sigma]
IMAGE_SIGNIF:    11.60 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +1  +1  +0  +0 -15  +1 
SUN_POSTN:       183.17d {+12h 12m 42s}   -1.37d {-01d 22' 28"}
SUN_DIST:         81.41 [deg]   Sun_angle= -5.4 [hr] (East of Sun)
MOON_POSTN:      225.99d {+15h 03m 57s}  -21.82d {-21d 48' 55"}
MOON_DIST:        51.06 [deg]
MOON_ILLUM:      16 [%]
GAL_COORDS:       36.47, 22.57 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      262.68, 36.33 [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 = 37.89,19.86 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 26 Sep 06 16:49:56 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     231231,   Seg_Num: 0
POINT_RA:        263.948d {+17h 35m 48s} (J2000)
POINT_DEC:       +13.048d {+13d 02' 54"} (J2000)
IMG_START_DATE:  14004 TJD;   269 DOY;   06/09/26
IMG_START_TIME:  60581.80 SOD {16:49:41.80} UT,   60.0 [sec] since BAT Trigger Time
COUNTS:          8    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        1    Max_iter_allowed= 4
ERROR_CODE:      1
COMMENTS:        SWIFT-XRT Nack Position.  
COMMENTS:        No source found in the image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 26 Sep 06 16:52:20 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     231231,   Seg_Num: 0
GRB_RA:          263.955d {+17h 35m 49s} (J2000),
                 264.033d {+17h 36m 08s} (current),
                 263.379d {+17h 33m 31s} (1950)
GRB_DEC:         +13.041d {+13d 02' 29"} (J2000),
                 +13.037d {+13d 02' 15"} (current),
                 +13.072d {+13d 04' 20"} (1950)
GRB_DATE:        14004 TJD;   269 DOY;   06/09/26
GRB_TIME:        60521.85 SOD {16:48:41.85} UT
TRIGGER_INDEX:   137
GRB_PHI:          98.06 [deg]
GRB_THETA:         9.10 [deg]
DELTA_TIME:      -11.00 [sec]
TRIGGER_DUR:     1.024 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     17.32 [sigma]
IMAGE_SIGNIF:    11.60 [sigma]
LC_URL:          sw00231231000msb.lc
SUN_POSTN:       183.18d {+12h 12m 42s}   -1.38d {-01d 22' 31"}
SUN_DIST:         81.41 [deg]   Sun_angle= -5.4 [hr] (East of Sun)
MOON_POSTN:      226.02d {+15h 04m 04s}  -21.83d {-21d 49' 29"}
MOON_DIST:        51.05 [deg]
MOON_ILLUM:      16 [%]
GAL_COORDS:       36.47, 22.57 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      262.68, 36.33 [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 = 37.89,19.86 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 26 Sep 06 16:56:40 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     231231,   Seg_Num: 0
POINT_RA:        263.948d {+17h 35m 47s} (J2000)
POINT_DEC:       +13.048d {+13d 02' 53"} (J2000)
POINT_ROLL:      266.531d
IMG_START_DATE:  14004 TJD;   269 DOY;   06/09/26
IMG_START_TIME:  60578.49 SOD {16:49:38.49} UT,   56.6 [sec] since BAT Trigger Time
FILTER:          3, V
BKG_MEAN:        1.530
N_STARS:         183
X_OFFSET:        394 [pixels]
Y_OFFSET:        540 [pixels]
X_MAX:           1353 [pixels]
Y_MAX:           1499 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00231231000msufc0056.fits
SUN_POSTN:       183.18d {+12h 12m 43s}   -1.38d {-01d 22' 35"}
SUN_DIST:         81.40 [deg]   Sun_angle= -5.4 [hr] (East of Sun)
MOON_POSTN:      226.05d {+15h 04m 13s}  -21.84d {-21d 50' 12"}
MOON_DIST:        51.03 [deg]
MOON_ILLUM:      16 [%]
GAL_COORDS:       36.47, 22.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      262.67, 36.33 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 26 Sep 06 16:57:05 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     231231,   Seg_Num: 0
POINT_RA:        263.948d {+17h 35m 47s} (J2000)
POINT_DEC:       +13.048d {+13d 02' 53"} (J2000)
POINT_ROLL:      266.531d
IMG_START_DATE:  14004 TJD;   269 DOY;   06/09/26
IMG_START_TIME:  60578.49 SOD {16:49:38.49} UT,   56.6 [sec] since BAT Trigger Time
FILTER:          3, V
BKG_MEAN:        1.530
N_STARS:         183
X_OFFSET:        394 [pixels]
Y_OFFSET:        540 [pixels]
X_MAX:           1353 [pixels]
Y_MAX:           1499 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00231231000msufc0056.fits
SUN_POSTN:       183.18d {+12h 12m 43s}   -1.38d {-01d 22' 36"}
SUN_DIST:         81.40 [deg]   Sun_angle= -5.4 [hr] (East of Sun)
MOON_POSTN:      226.06d {+15h 04m 14s}  -21.84d {-21d 50' 17"}
MOON_DIST:        51.03 [deg]
MOON_ILLUM:      16 [%]
GAL_COORDS:       36.47, 22.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      262.67, 36.33 [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:     Tue 26 Sep 06 16:58:45 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     231231,   Seg_Num: 0
POINT_RA:        263.948d {+17h 35m 47s} (J2000)
POINT_DEC:       +13.048d {+13d 02' 53"} (J2000)
ROLL:            266.531d
IMG_START_DATE:  14004 TJD;   269 DOY;   06/09/26
IMG_START_TIME:  60578.49 SOD {16:49:38.49} UT,   56.6 [sec] since BAT Trigger Time
FILTER:          3, V
EXPOSURE_ID:     180982179
X_OFFSET:        713 [pixels]
Y_OFFSET:        859 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       873
Y_GRB_POS:       1019
BINNING_INDEX:   1
IM_URL:          sw00231231000msuni0056.fits
SUN_POSTN:       183.18d {+12h 12m 43s}   -1.38d {-01d 22' 37"}
SUN_DIST:         81.40 [deg]   Sun_angle= -5.4 [hr] (East of Sun)
MOON_POSTN:      226.07d {+15h 04m 17s}  -21.84d {-21d 50' 33"}
MOON_DIST:        51.02 [deg]
MOON_ILLUM:      16 [%]
GAL_COORDS:       36.47, 22.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      262.67, 36.33 [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:     Tue 26 Sep 06 16:59:04 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     231231,   Seg_Num: 0
POINT_RA:        263.948d {+17h 35m 47s} (J2000)
POINT_DEC:       +13.048d {+13d 02' 53"} (J2000)
ROLL:            266.531d
IMG_START_DATE:  14004 TJD;   269 DOY;   06/09/26
IMG_START_TIME:  60578.49 SOD {16:49:38.49} UT,   56.6 [sec] since BAT Trigger Time
FILTER:          3, V
EXPOSURE_ID:     180982179
X_OFFSET:        713 [pixels]
Y_OFFSET:        859 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       873
Y_GRB_POS:       1019
BINNING_INDEX:   1
IM_URL:          sw00231231000msuni0056.fits
SUN_POSTN:       183.18d {+12h 12m 43s}   -1.38d {-01d 22' 38"}
SUN_DIST:         81.40 [deg]   Sun_angle= -5.4 [hr] (East of Sun)
MOON_POSTN:      226.07d {+15h 04m 18s}  -21.84d {-21d 50' 36"}
MOON_DIST:        51.02 [deg]
MOON_ILLUM:      16 [%]
GAL_COORDS:       36.47, 22.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      262.67, 36.33 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 26 Sep 06 17:00:20 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     231231,   Seg_Num: 0
GRB_RA:          263.9300d {+17h 35m 43.2s} (J2000),
                 264.0077d {+17h 36m 01.8s} (current),
                 263.3536d {+17h 33m 24.8s} (1950)
GRB_DEC:         +13.0395d {+13d 02' 22.2"} (J2000),
                 +13.0356d {+13d 02' 08.0"} (current),
                 +13.0703d {+13d 04' 13.1"} (1950)
GRB_ERROR:       11.9 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      5.00 [sigma]
IMG_START_DATE:  14004 TJD;   269 DOY;   06/09/26
IMG_START_TIME:  60581.80 SOD {16:49:41.80} UT,   60.0 [sec] since BAT Trigger Time
TAM[0-3]:        327.61 237.19 261.35 242.66
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       183.18d {+12h 12m 43s}   -1.38d {-01d 22' 39"}
SUN_DIST:         81.38 [deg]   Sun_angle= -5.4 [hr] (East of Sun)
MOON_POSTN:      226.09d {+15h 04m 20s}  -21.85d {-21d 50' 49"}
MOON_DIST:        51.00 [deg]
MOON_ILLUM:      16 [%]
GAL_COORDS:       36.45, 22.59 [deg] galactic lon,lat of the burst
ECL_COORDS:      262.65, 36.32 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        TAM values are not valid.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 26 Sep 06 17:03:48 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     231231,   Seg_Num: 0
POINT_RA:        263.945d {+17h 35m 47s} (J2000)
POINT_DEC:       +13.048d {+13d 02' 54"} (J2000)
POINT_ROLL:      266.529d
IMG_START_DATE:  14004 TJD;   269 DOY;   06/09/26
IMG_START_TIME:  61386.00 SOD {17:03:06.00} UT,   864.2 [sec] since BAT Trigger Time
FILTER:          3, V
BKG_MEAN:        0.048
N_STARS:         31
X_OFFSET:        394 [pixels]
Y_OFFSET:        540 [pixels]
X_MAX:           1353 [pixels]
Y_MAX:           1499 [pixels]
DET_THRESH:      3
PHOTO_THRESH:    2
SL_URL:          sw00231231000msufc0864.fits
SUN_POSTN:       183.18d {+12h 12m 44s}   -1.38d {-01d 22' 42"}
SUN_DIST:         81.40 [deg]   Sun_angle= -5.4 [hr] (East of Sun)
MOON_POSTN:      226.11d {+15h 04m 28s}  -21.86d {-21d 51' 24"}
MOON_DIST:        51.00 [deg]
MOON_ILLUM:      16 [%]
GAL_COORDS:       36.47, 22.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      262.67, 36.33 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 26 Sep 06 17:04:03 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     231231,   Seg_Num: 0
POINT_RA:        263.945d {+17h 35m 47s} (J2000)
POINT_DEC:       +13.048d {+13d 02' 54"} (J2000)
POINT_ROLL:      266.529d
IMG_START_DATE:  14004 TJD;   269 DOY;   06/09/26
IMG_START_TIME:  61386.00 SOD {17:03:06.00} UT,   864.2 [sec] since BAT Trigger Time
FILTER:          3, V
BKG_MEAN:        0.048
N_STARS:         31
X_OFFSET:        394 [pixels]
Y_OFFSET:        540 [pixels]
X_MAX:           1353 [pixels]
Y_MAX:           1499 [pixels]
DET_THRESH:      3
PHOTO_THRESH:    2
SL_URL:          sw00231231000msufc0864.fits
SUN_POSTN:       183.18d {+12h 12m 44s}   -1.38d {-01d 22' 43"}
SUN_DIST:         81.40 [deg]   Sun_angle= -5.4 [hr] (East of Sun)
MOON_POSTN:      226.12d {+15h 04m 28s}  -21.86d {-21d 51' 26"}
MOON_DIST:        51.00 [deg]
MOON_ILLUM:      16 [%]
GAL_COORDS:       36.47, 22.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      262.67, 36.33 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        If you have elected to receive attachments:  
COMMENTS:        The uvot_catalog_srclist.fits.gz file does not exist; skipping the attachment.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 26 Sep 06 17:04:48 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     231231,   Seg_Num: 0
POINT_RA:        263.945d {+17h 35m 47s} (J2000)
POINT_DEC:       +13.048d {+13d 02' 54"} (J2000)
ROLL:            266.529d
IMG_START_DATE:  14004 TJD;   269 DOY;   06/09/26
IMG_START_TIME:  61386.00 SOD {17:03:06.00} UT,   864.2 [sec] since BAT Trigger Time
FILTER:          3, V
EXPOSURE_ID:     180982987
X_OFFSET:        713 [pixels]
Y_OFFSET:        859 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       873
Y_GRB_POS:       1019
BINNING_INDEX:   1
IM_URL:          sw00231231000msuni0864.fits
SUN_POSTN:       183.18d {+12h 12m 44s}   -1.38d {-01d 22' 43"}
SUN_DIST:         81.40 [deg]   Sun_angle= -5.4 [hr] (East of Sun)
MOON_POSTN:      226.12d {+15h 04m 30s}  -21.86d {-21d 51' 34"}
MOON_DIST:        50.99 [deg]
MOON_ILLUM:      16 [%]
GAL_COORDS:       36.47, 22.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      262.67, 36.33 [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:     Tue 26 Sep 06 17:05:08 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     231231,   Seg_Num: 0
POINT_RA:        263.945d {+17h 35m 47s} (J2000)
POINT_DEC:       +13.048d {+13d 02' 54"} (J2000)
ROLL:            266.529d
IMG_START_DATE:  14004 TJD;   269 DOY;   06/09/26
IMG_START_TIME:  61386.00 SOD {17:03:06.00} UT,   864.2 [sec] since BAT Trigger Time
FILTER:          3, V
EXPOSURE_ID:     180982987
X_OFFSET:        713 [pixels]
Y_OFFSET:        859 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       873
Y_GRB_POS:       1019
BINNING_INDEX:   1
IM_URL:          sw00231231000msuni0864.fits
SUN_POSTN:       183.18d {+12h 12m 44s}   -1.38d {-01d 22' 44"}
SUN_DIST:         81.40 [deg]   Sun_angle= -5.4 [hr] (East of Sun)
MOON_POSTN:      226.13d {+15h 04m 30s}  -21.86d {-21d 51' 37"}
MOON_DIST:        50.99 [deg]
MOON_ILLUM:      16 [%]
GAL_COORDS:       36.47, 22.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      262.67, 36.33 [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 #5612
S. T. Holland (GSFC/USRA), S. D. Barthelmy (GSFC), D. N. Burrows (PSU), M. Capalbi (ASDC), M.L. Conciatore (ASDC), J. R. Cummings (NASA/UMBC), N. Gehrels (NASA/GSFC), C. Guidorzi (Univ Bicocca&INAF-OAB), J. A. Kennea (PSU), H. A. Krimm (GSFC/USRA), V. Mangano (INAF-IASFPA), C. B. Markwardt (GSFC/UMD), F. E. Marshall (NASA/GSFC), J. P. Osborne (U Leicester), K. L. Page (U Leicester), D. M. Palmer (LANL), P. Romano (INAF-OAB), G. Sato (GSFC/ISAS), M. Stamatikos (NASA/ORAU), D. E. Vanden Berk (PSU) and H. Ziaeepour (UCL-MSSL) report on behalf of the Swift Team:
At 16:48:41 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 060926 (trigger=231231). Swift slewed immediately to the burst. The BAT on-board calculated location is RA,Dec 263.955, +13.041 {17h 35m 49s, +13d 02' 29"} (J2000) with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows two overlapping peaks with a total duration of about 10 sec. The peak count rate was ~1500 counts/sec (15-350 keV), at ~1 sec after the trigger.
The XRT began taking data at 16:49:41 UT, 60 seconds after the BAT trigger. The XRT on-board centroid algorithm did not find a source in the image, however analysis of a 2.5 s exposure in the initial data products reveals a point source at the following location:
```
RA(J2000)= 17h 35m 43.2s 
Dec(J2000) = +13d 02m 22.1s  
```
with an uncertainty of 12 arcseconds radius (90% confidence). This source is 87 arcseconds from the BAT position.
UVOT took a finding chart exposure of 400 seconds with the V filter starting 57 seconds after the BAT trigger. There is a low significance candidate afterglow in the rapidly available 2.7'x2.7' sub-image at
```
 RA(J2000)  =  17:35:43.66 = 263.9319
 DEC(J2000) = +13:02:18.6  =  13.0385
```
with a 1-sigma error radius of about 0.5 arc sec. This position is 7.6 arc sec. from the center of the XRT error circle. The estimated magnitude is 19.7 with a 1-sigma error of about 0.5 mag. No correction has been made for the expected extinction of about 0.5 magnitudes.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 26 Sep 06 17:24:21 UT
NOTICE_TYPE:     Swift-UVOT Position
TRIGGER_NUM:     231231,   Seg_Num: 0
GRB_RA:          263.9318d {+17h 35m 43.63s} (J2000),
                 264.0095d {+17h 36m 02.27s} (current),
                 263.3554d {+17h 33m 25.30s} (1950)
GRB_DEC:         +13.0385d {+13d 02' 18.6"} (J2000),
                 +13.0346d {+13d 02' 04.4"} (current),
                 +13.0693d {+13d 04' 09.5"} (1950)
GRB_ERROR:       0.4 [arcsec radius, statistical only]
GRB_MAG:         19.70 +/- 0.50 [mag]
FILTER:          3, V
IMG_START_DATE:  14004 TJD;   269 DOY;   06/09/26
IMG_START_TIME:  60578.00 SOD {16:49:38.00} UT,   56.2 [sec] since BAT Trigger Time
SUN_POSTN:       183.20d {+12h 12m 47s}   -1.38d {-01d 23' 02"}
SUN_DIST:         81.37 [deg]   Sun_angle= -5.4 [hr] (East of Sun)
MOON_POSTN:      226.29d {+15h 05m 10s}  -21.91d {-21d 54' 49"}
MOON_DIST:        50.89 [deg]
MOON_ILLUM:      16 [%]
GAL_COORDS:       36.45, 22.59 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      262.66, 36.32 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT UVOT Position Notice.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The weak source is at the edge of the fov.

GCN Circular #5613
V. Lipunov, V.Kornilov, D.Kuvshinov, N.Tyurina, A.Belinski, E.Gorbovskoy, A.Krylov,G.Borisov, A.Sankovich, V.Vladimirov, P.Gritsyk
Sternberg Astronomical Institute, Moscow Union 'Optic' MASTER robotic system (http://observ.pereplet.ru) responded to GRB060926 (Holland et al., GCN Circ 5612). The first image was started at 2006-09-26 16:49:57 UT, 76 s after the GRB time.
The unfiltered image is calibrated relative to USNO A2.0 (0.8 R + 0.2 B). The robot did not find OT-candidate in error box brighter then 17.0 (s/n=10).
The reduction is continuing. This work is supported by RFFI 04-02-16411 grant. This message can be cited. Mailto: lipunov@sai.msu.ru
GCN Circular #5614
A. Stefanescu, F.Schrey, S. Duscha, G. Kanbach, M. Muehlegger, N. Primak, H. Steinle (MPE Garching) of the OPTIMA-Burst Team report the following:
"OPTIMA-Burst at the 1.3m Skinakas Observatory, of the University of Crete, Greece observed the Swift XRT-errorcircle of GRB 060926 (GCN Circ 5612, S.T. Holland et al.) at 17:19UT (36 min after the Burst, mid-exposure). We detected a faint source at the UVOT-Position (GCN Circular #5612). We estimate the brightness of this source in a 10 min R-Band image as 19.5+-.1mag. There is no source at this position in the USNO-A2 Catalog, and no minor planet according to MPChecker."
GCN Circular #5615
J.French (UCD Dublin) and P.Kubanek (AsU AV CR Ondrejov & ISDC Versoix) report on behalf of the Watcher collaboration:
The Watcher 0.4 m telescope, located at the Boyden Observatory, South Africa, began observing the location of GRB060926 at 16:49:44 UT (61s after the burst). Initial observations were carried out under twilight conditions, restricting Watcher's limiting magnitude for these early 10s unfiltered exposures to ~ 13mag. We do not detect any new source down to this limit. Further observations and analysis are ongoing, as observing conditions improve.
GCN Circular #5616
A. de Ugarte Postigo (IAA-CSIC Granada) & P. Kubanek (ASU AV CR ndrejov & ISDC Versoix) on behalf of a larger collaboration report:
"The 0.6m BOOTES-IR telescope, located at IAA-CSIC Observatorio de Sierra Nevada in Granada (Spain), observed the SWIFT error box for GRB 060926 (Holland et al. GCN 5612) starting at 18:48 UT (2.0 h after the burst) in R-band. We do not detect the optical counterpart during the first hour of observations down to a limiting 3-sigma magnitude of R ~ 20.3. Further analysis is ongoing.
This message is quotable."
GCN Circular #5618
U. Kiziloglu (METU), I. Khamitov (TUG), Z. Aslan (TUG), E. Gogus (Sabanci Uni.), R. Burenin, M. Pavlinsky, R. Sunyaev (IKI) I. Bikmaev, N. Sakhibullin (KSU/AST),
report:
We observed the field around the XRT error circle (Holland et al., GCN5612) of GRB060926 (Swift trigger 231231) with the Russian-Turkish 1.5-m telescope (RTT150, Bakirlitepe, TUBITAK National Observatory, Turkey), at the 17:45 UT of Sep 26, about 56 minutes after the burst. A series of frames (3*300sec) were taken in R band with TFOSC. At the position of UVOT afterglow candidate (GCN5612) we detect a faint source which faded more than 1 mag according to early detection (Stefanescu et al., GCN5614). Using USNO-B1 star (RA=17:35:42.06, DEC=+13:02:11.7, R2MAG=18.96) we estimate the following R magnitude for the source:
```
    t-t0    m_R     err
    (min)	
    66.5    20.8    0.1	
```
This message may be cited.

GCN Circular #5619
V. Lipunov, V.Kornilov, D.Kuvshinov, N.Tyurina, A.Belinski, E.Gorbovskoy, A.Krylov, G.Borisov, A.Sankovich, V.Vladimirov, P.Gritsyk
Sternberg Astronomical Institute, Moscow Union 'Optic' MASTER robotic system (http://observ.pereplet.ru) responded to GRB060926 (Holland et al., GCN Circ 5612). The first image was started at 2006-09-26 16:49:57 UT, 76 s after the GRB time. The unfiltered image is calibrated relative to USNO A2.0 (0.8 R + 0.2 B). We see OT (Holland et al., GCN Circ 5612). Our results:

   T-T_grb             exp_time           m (close to R)    S/N
  
  76 s - 106 s          30 s                   >17           5
  76 s - 360 s         5x30 s                  18+-0.3
  76 s - 820 s        10x30 s                  18.5+-0.3

Reduction is continued. Images are available:

http://pereplet.sai.msu.ru/nauka/i12.jpg
http://pereplet.sai.msu.ru/nauka/i12a.jpg 
http://pereplet.sai.msu.ru/nauka/i12b.jpg
Small part with OT
http://observ.pereplet.ru/images/GRB060926/GRB060926_5.jpg 
http://observ.pereplet.ru/images/GRB060926/GRB060926_10.jpg
This work is supported by RFFI  04-02-16411 grant.
This message can be cited.     
Mailto: lipunov@sai.msu.ru

GCN Circular #5621
J. Cummings (GSFC/UMBC), L. Barbier (GSFC), S. D. Barthelmy (GSFC), E. Fenimore (LANL), N. Gehrels (GSFC), S. T. Holland (GSFC/USRA), D. Hullinger (BYU-Idaho), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), 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-119 to T+183 sec from recent telemetry downlinks, we report further analysis of BAT GRB 060926 (trigger #231231) (Holland, et al., GCN Circ. 5612). The BAT ground-calculated position is RA,Dec = 263.925, 13.039 deg {17h 35m 41.9s, 13d 2' 21.5"} (J2000) +- 1.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 94%.
The mask-weighted lightcuve shows a single FRED peak starting at T-1 sec, peaking at T+1 sec, and ending approximately at T+10 sec. T90 (15-350 keV) is 8.0 +- 0.1 sec (estimated error including systematics).
The time-averaged spectrum from T-0.1 to T+8.6 is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.54 +- 0.23. The fluence in the 15-150 keV band is 2.2 +- 0.3 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+0.38 sec in the 15-150 keV band is 1.1 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
GCN Circular #5622
M. Perri, M. Capalbi, M.L. Conciatore (ASDC), D.N. Burrows (PSU) and S.T. Holland (GSFC/USRA) report on behalf of the Swift XRT team:
We have analysed the first three orbits of Swift XRT data on the BAT GRB 060926 (Holland, et al., GCN Circ. 5612). A 4.7 ks Photon Counting mode image provides a refined XRT position:
```
RA(J2000)  =  17h 35m 43.93s
Dec(J2000) = +13d 02' 18.4"
```
with an uncertainty of 5.9" (90% containment). This is 29.8" away from the center of the BAT refined position (Cummings et al., GCN Circ. 5621). This localization lies 11.3" from the XRT position and 4.0" from the UVOT position quoted in GCN Circ. 5612 (Holland, et al.).
The 0.3-10 keV X-ray light curve during the first orbit shows a flare at T+430s. Between second and third orbit a power-law decline with a temporal index of -1.6+/-0.4 is observed.
The X-ray spectrum covering the time period from T+67s to T+878s is well fit by an absorbed power-law with a photon index of 2.1(+/-0.3) and column density of (2.2+/-0.9)e21 cm**-2. We note the Galactic column density in the direction of the source is 7.3e20 cm**-2.
Assuming the X-ray emission continues to decline at the same rate, we predict a 0.3-10 keV XRT count rate of ~1e-3 count/s at T+24hr, which corresponds to an observed 0.3-10 keV flux of ~4e-14 erg/cm**2/s.
This circular is an official product of the Swift XRT Team.
GCN Circular #5623
A. Stefanescu, F. Schrey, S. Duscha, G. Kanbach, M. Muehlegger, N. Primak, H. Steinle (MPE Garching) of the OPTIMA-Burst Team report the following:
We have observed the OT of GRB 060926 under unfavorable weather conditions until it became unobservable at ~18:40 UT. To make comparision easier with GCN 5618 (U. Kiziloglu et al.), we have callibrated our observations against the R2-magnitudes of 4 nearby USNO-B1 stars (1030-0324059, 1030-0324042, 1030-0324039, 1030-0324046). We estimate the magnitude of the OT as follows:
```
    t-t_BAT        exp-time
[min] (mid-exp)     [s]         R_mag
-----------------------------------------------
    35.4             600         20.3 +-0.5
    59.7             600         20.6 +-0.5
    72.7             600         20.7 +-0.7
    90.7             2x 1200     21.0 +-0.7
    101.2            1200        21.1 +-0.7
```
We fitted these values with a powerlaw with a decay index of 0.73 +-0.1. This is significantly shallower than the powerlaw between the MASTER observations (GCN 5619, V. Lipunov et al.) and ours, with a decay index of 0.90 +-0.06 - allthough this could be due to incompatibilities in zero-point.
We thank J. Papamastorakis of the University of Crete and his team for the possibility to use the 1.3m Telescope at Skinakas Observatory for a prolonged period of time.
GCN Circular #5625
P. Roming (PSU) and S. T. Holland (GSFC/USRA) report on behalf of the Swift-UVOT team:
The Swift UVOT began observing GRB 060926, 57 seconds after the BAT trigger (GCN 5612). We detect a source at the 4.8- and 4.3-sigma levels in the V- and UVW1- (251 nm) filters, respectively. The magnitude of the source is 19.0+/-0.2 (V-filter) and 18.8+/-0.2 (UVW1-filter) as determined by the Swift analysis tool, uvotsource.
No optical afterglow is detected at the 3-sigma level in individual or coadded exposures in the UVOT UVW2-, UVM2-, U-, or B-filters. The 3-sigma limiting magnitudes for the coadded images of the UVOT filters are listed below:
```
Filter		T_range(s)	Exp(s)		Upper Limit (3-sigma)
UVW2		551-6405	432		20.1
UVM2		463-10840	1366		20.4
U		511-12283	968		20.8
B		535-6199	422		20.6
```
where T_range is the start and end times of the coadded exposures. No correction has been made for Galactic reddening along the line of sight (E(B-V) = 0.16).
No images were taken in the White-filter by the UVOT since bright stars were in the field-of-view.
GCN Circular #5626
S. Piranomonte (INAF-OAR), S. Covino (INAF/OABr), D. Malesani (SISSA), F. Fiore (INAF-OAR), G. Tagliaferri (INAF/OABr), G. Chincarini (Univ. Milano-Bicocca), L. Stella (INAF-OAR), on behalf of the MISTICI collaboration, report:
We observed the optical afterglow of GRB060926 detected by Swift (S.T. Holland et al., GCN 5612) with ESO's Very Large Telescope UT2 (Kueyen) at Paranal, Chile. We obtained three FORS1 spectra with a total exposure of 4800 seconds starting approximately 8 hours after the burst, with the 300V grism and a 1" slit, providing a wavelength coverage of 3800-8900.
We clearly detect a damped Ly alpha line and various other absorption features such as Si II,Si IV, CIV at a redshift of z=3.20.
It's a pleasure to thank the excellent support of the Paranal staff, and in particular that of Hugues Sana.
This message can be cited.
GCN Circular #5632
V. Lipunov, V.Kornilov, D.Kuvshinov, N.Tyurina, A.Belinski, E.Gorbovskoy, A.Krylov, G.Borisov, A.Sankovich, V.Vladimirov, P.Gritsyk
Sternberg Astronomical Institute, Moscow Union 'Optic'
MASTER robotic system (http://observ.pereplet.ru) responded to GRB060926 (Holland et al., GCN Circ 5612) under the good conditions. The first image was started at 2006-09-26 16:49:57 UT, 76 s after the GRB time (355 mm telescope, 6 square degrees FOV, 2.1'' per pix, CCD Alta U16). The unfiltered image is calibrated relative to USNO A2.0 (0.8 R + 0.2 B). We find faint OT on the first and on the coadded images at position:
```
aplha = 17 35 43.66
dec   = 13 02 18.3
err = +- 0.7''
```
wich coincided with the Holland et al.(GCN Circ 5612) OT position.
Our results:
```
   T-T_grb       mean time      exp_time           m (close to R)  S/N

  76 s - 106 s      91 s         30 s                 17.5+-0.3    4.5
  76 s - 360 s     218 s        5x30 s                18.2+-0.3     4
  76 s - 820 s     448 s       10x30 s                18.3+-0.3     4
  76 s - 1411 s    743 s       15x30 s                18.7+-0.3     4
1024 s - 1810 s  1417 s       10x30 s                  >19.7
```
We fitted these values with a powerlaw with a decay index of 0.69 up to 743 s. This is steeper then the powerlaw OPTIMA-Burst observations (GCN 5623, A. Stefanescu et al.). The light curve is available at http://observ.pereplet.ru/images/GRB060926/lc.jpg .
GCN Circular #5637
V. D'Elia, S.Piranomonte (INAF/OAR), S. Covino (INAF/OABr), D. Malesani (SISSA/ISAS), F. Fiore, A. Antonelli (INAF/OAR), G. Tagliaferri (INAF/OABr), L. Stella (INAF/OAR), and G. Chincarini (Univ. Milano-Bicocca), report on behalf of the MISTICI collaboration:
Using updated calibration files, we have refined the redshift obtained at the VLT for GRB 060926 (Piranomonte et al., GCN 5626; Holland et al., GCN 5612).
We measure a redshift of z = 3.208 based on the detection of the following lines in absorption: Lyman-alpha, OI_1302 SiII_1304, CII_1334, CII_1347, SiIV_1393, SiIV_1402, SiII_1526, SiII*_1533, CIV_1540, CIV_1550, FeII_1608, FeII_1611, AlII_1670, and SiII_1808.
This message can be cited.
GCN Circular #5645
P. Roming (PSU) and S. T. Holland (GSFC/USRA) report on behalf of the Swift-UVOT team:
Due to an error in the flux calculation, the reported UVW1 (251 nm) filter detection in GCN 5625 is not real. No optical afterglow is detected at the 3-sigma level in individual or coadded exposures in this filter. The 3-sigma limiting magnitude for the coadded images is listed below:
```
Filter      T_range(s)      Exp(s)     Upper Limit (3-sigma)
UVW1         487-11748      1337       20.4
```
where T_range is the start and end times of the coadded exposures. No correction has been made for Galactic reddening along the line of sight (E(B-V) = 0.16). We also point out that the 4.8-sigma level V-filter detection report in GCN 5625 is real. We apologize for any inconvenience this error has created.
GCN Circular #5680
P. Chandra (UVA/NRAO) and D. A. Frail (NRAO) report on behalf of the Caltech-NRAO-Carnegie GRB Collaboration:
"We used the Very Large Array to observe the field of view toward GRB060926 (GCN 5612) at a frequency of 8.46 GHz on 2006 October 1st starting at 2.07 UT and on 2006 October 2nd starting at 2.00 UT. The peak radio brightness at the position of the afterglow (GCN 5622) is -24 uJy =B1 58 uJy and -18uJy =B1 56 uJy respectively.
The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc."
GCN Report 1.1
GCN_Report 1.1 has been posted: http://gcn.gsfc.nasa.gov/reports/report_1_1.pdf by S.T.Holland et al. titled: "Swift Observations of GRB 060926"
GCN Report 1.2
GCN_Report 1.2 has been posted: http://gcn.gsfc.nasa.gov/reports/report_1_2.pdf by S.T.Holland titled: "Swift Observations of GRB 060926"
GCN Circular #5901
V. Lipunov, V.Kornilov, D.Kuvshinov, N.Tyurina, A.Belinski, E.Gorbovskoy, A.Krylov, G.Borisov, A.Sankovich, V.Vladimirov, P.Gritsyk
Sternberg Astronomical Institute, Moscow Union 'Optic'
MASTER robotic system (http://observ.pereplet.ru) responded to GRB060926 (Holland et al., GCN Circ 5612) under the good conditions (V. Lipunov et al., GCN Circ 5632).
The first image was started at 2006-09-26 16:49:57 UT, 76 s after the GRB time (355 mm telescope, 6 square degrees FOV, 2.1'' per pix, CCD Alta U16). The unfiltered image is calibrated relative to USNO A2.0 (0.8 R + 0.2 B). We find (Lipunov et al., GCN5632) faint OT on the first and on the coadded images at position:
```
aplha = 17 35 43.66
dec   = 13 02 18.3
err = +- 0.7''
```
wich coincided with the Holland et al.(GCN Circ 5612) OT position.
We have refind analysis of the images. We discovery optical flare around 500-700 s after the GRB time (see picture):
```
Start    Mean   Exposure        Magnitude            Flux, 
time     time     time                          erg/(sm2*sec*eV)

 76 s     91 s     30 s         17.3+-0.3        (1,4+-0,3)E-13 
150 s    165 s     30 s     	18.5+-0.3        (4,6+-1,1)E-14 
165 s	 343 s    5x30 s        19.3+-0.3        (2,2+-0,5)E-14 
255 s    432 s    5x30 s        18.9+-0.3	 (3,2+-0,8)E-14 
343 s	 519 s    5x30 s        18.5+-0.3    	 (4,6+-1,1)E-14 
432 s	 608 s    5x30 s        18.3+-0.3    	 (5,8+-1,3)E-14
519 s	 707 s    5x30 s        18.4+-0.3        (5,1+-1,2)E-14 
608 s	 804 s	  5x30 s        18.7+-0.3	 (3,9+-0,9)E-14 
707 s	1001 s    5x30 s        20.0+-0.3    	 (1,2+-0,3)E-14 
804 s	1200 s    5x30 s        20.1+-0.3    	 (1,1+-0,3)E-14 
901 s	1298 s    5x30 s      > 20.1+-0.3    	<(1,1+-0,3)E-14
```
The light curve is available at http://observ.pereplet.ru/images/GRB060926/light_curve_new.jpg
Between 91s and 255s a power-law decline with a temporal index of -1.40+/-0.24 is estimated. Between 707s and 1200s a power-law decline with a temporal index of -3.30+/-0.70 is estimated. After 1000 s a power-law decline with a temporal index 0.73 +-0.1 was observed (A. Stefanescu et al., GCN 5623).
We remember that X-ray flare in GRB 060926 was descovered by XRT team (M. Perri et al., GCN 5622).
The X-ray spectrum covering the time period from T+67s to T+878s is well fit by an absorbed power-law with a photon index of 2.1(+/-0.3) and column density of (2.2+/-0.9)e21 cm**-2 (M. Perri et al., GCN 5622). They note the Galactic column density in the direction of the source is 7.3e20 cm**-2 . This means that absorbtion is about 1 magnitude in our band. The optical-xray data is well fit by power-low with a photon index of 1.7+-0.2 during all our time observation.
We thanks to Dr.K.A.Postnov for usefull discussion and comments.
This work is supported by RFFI 04-02-16411 grant. This message can be cited. Mailto: lipunov@sai.msu.ru

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Jochen Greiner, last update: 07-Dec-2006 [Disclaimer]