Gamma-ray Burst 070810

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 10 Aug 07 02:13:28 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     287364,   Seg_Num: 0
POINT_RA:        189.973d {+12h 39m 53s} (J2000)
POINT_DEC:       +10.739d {+10d 44' 20"} (J2000)
IMG_START_DATE:  14322 TJD;   222 DOY;   07/08/10
IMG_START_TIME:  8000.16 SOD {02:13:20.16} UT,   24662.8 [sec] since BAT Trigger Time
COUNTS:          5    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.

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 10 Aug 07 02:15:32 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     287364,   Seg_Num: 0
GRB_RA:          189.939d {+12h 39m 45s} (J2000),
                 190.035d {+12h 40m 08s} (current),
                 189.308d {+12h 37m 14s} (1950)
GRB_DEC:         +10.744d {+10d 44' 40"} (J2000),
                 +10.703d {+10d 42' 10"} (current),
                 +11.019d {+11d 01' 08"} (1950)
GRB_DATE:        14322 TJD;   222 DOY;   07/08/10
GRB_TIME:        7912.41 SOD {02:11:52.41} UT
TRIGGER_INDEX:   139
GRB_PHI:         -40.00 [deg]
GRB_THETA:        35.57 [deg]
DELTA_TIME:      64.00 [sec]
TRIGGER_DUR:      [sec],  copy from BAT_POS unavailable
SOLN_STATUS:     0x0
RATE_SIGNIF:     19.15 [sigma]
IMAGE_SIGNIF:    10.98 [sigma]
LC_URL:          sw00287364000msb.lc
SUN_POSTN:       139.56d {+09h 18m 13s}  +15.71d {+15d 42' 29"}
SUN_DIST:         49.29 [deg]   Sun_angle= -3.4 [hr] (East of Sun)
MOON_POSTN:      103.11d {+06h 52m 27s}  +27.21d {+27d 12' 45"}
MOON_DIST:        82.42 [deg]
MOON_ILLUM:      9 [%]
GAL_COORDS:      292.85, 73.39 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      184.81, 13.80 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Lightcurve.  
COMMENTS:        This does not match any source in the ground catalog.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 10 Aug 07 02:16:21 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     287364,   Seg_Num: 0
POINT_RA:        189.973d {+12h 39m 53s} (J2000)
POINT_DEC:       +10.739d {+10d 44' 20"} (J2000)
POINT_ROLL:      281.580d
IMG_START_DATE:  14322 TJD;   222 DOY;   07/08/10
IMG_START_TIME:  8003.93 SOD {02:13:23.93} UT,   24666.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.811
N_STARS:         13
X_OFFSET:        702 [pixels]
Y_OFFSET:        443 [pixels]
X_MAX:           1661 [pixels]
Y_MAX:           1402 [pixels]
DET_THRESH:      16
PHOTO_THRESH:    9
SL_URL:          sw00287364000msufc24666.fits
SUN_POSTN:       139.56d {+09h 18m 14s}  +15.71d {+15d 42' 28"}
SUN_DIST:         49.32 [deg]   Sun_angle= -3.4 [hr] (East of Sun)
MOON_POSTN:      103.12d {+06h 52m 29s}  +27.21d {+27d 12' 41"}
MOON_DIST:        82.45 [deg]
MOON_ILLUM:      9 [%]
GAL_COORDS:      292.97, 73.39 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      184.84, 13.81 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 10 Aug 07 02:16:44 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     287364,   Seg_Num: 0
POINT_RA:        189.973d {+12h 39m 53s} (J2000)
POINT_DEC:       +10.739d {+10d 44' 20"} (J2000)
POINT_ROLL:      281.580d
IMG_START_DATE:  14322 TJD;   222 DOY;   07/08/10
IMG_START_TIME:  8003.93 SOD {02:13:23.93} UT,   24666.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.811
N_STARS:         13
X_OFFSET:        702 [pixels]
Y_OFFSET:        443 [pixels]
X_MAX:           1661 [pixels]
Y_MAX:           1402 [pixels]
DET_THRESH:      16
PHOTO_THRESH:    9
SL_URL:          sw00287364000msufc24666.fits
SUN_POSTN:       139.56d {+09h 18m 14s}  +15.71d {+15d 42' 28"}
SUN_DIST:         49.32 [deg]   Sun_angle= -3.4 [hr] (East of Sun)
MOON_POSTN:      103.13d {+06h 52m 30s}  +27.21d {+27d 12' 39"}
MOON_DIST:        82.44 [deg]
MOON_ILLUM:      9 [%]
GAL_COORDS:      292.97, 73.39 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      184.84, 13.81 [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:     Fri 10 Aug 07 02:18:14 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     287364,   Seg_Num: 0
POINT_RA:        189.973d {+12h 39m 53s} (J2000)
POINT_DEC:       +10.739d {+10d 44' 20"} (J2000)
ROLL:            281.580d
IMG_START_DATE:  14322 TJD;   222 DOY;   07/08/10
IMG_START_TIME:  8003.93 SOD {02:13:23.93} UT,   24666.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     208404806
X_OFFSET:        1021 [pixels]
Y_OFFSET:        762 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1181
Y_GRB_POS:       922
BINNING_INDEX:   1
IM_URL:          sw00287364000msuni24666.fits
SUN_POSTN:       139.56d {+09h 18m 14s}  +15.71d {+15d 42' 27"}
SUN_DIST:         49.32 [deg]   Sun_angle= -3.4 [hr] (East of Sun)
MOON_POSTN:      103.14d {+06h 52m 34s}  +27.21d {+27d 12' 32"}
MOON_DIST:        82.43 [deg]
MOON_ILLUM:      9 [%]
GAL_COORDS:      292.97, 73.39 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      184.84, 13.81 [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:     Fri 10 Aug 07 02:18:32 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     287364,   Seg_Num: 0
POINT_RA:        189.973d {+12h 39m 53s} (J2000)
POINT_DEC:       +10.739d {+10d 44' 20"} (J2000)
ROLL:            281.580d
IMG_START_DATE:  14322 TJD;   222 DOY;   07/08/10
IMG_START_TIME:  8003.93 SOD {02:13:23.93} UT,   24666.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     208404806
X_OFFSET:        1021 [pixels]
Y_OFFSET:        762 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1181
Y_GRB_POS:       922
BINNING_INDEX:   1
IM_URL:          sw00287364000msuni24666.fits
SUN_POSTN:       139.56d {+09h 18m 14s}  +15.71d {+15d 42' 26"}
SUN_DIST:         49.32 [deg]   Sun_angle= -3.4 [hr] (East of Sun)
MOON_POSTN:      103.15d {+06h 52m 35s}  +27.21d {+27d 12' 30"}
MOON_DIST:        82.43 [deg]
MOON_ILLUM:      9 [%]
GAL_COORDS:      292.97, 73.39 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      184.84, 13.81 [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:        If you have elected to receive attachments:  
COMMENTS:        The uvot_sources_image.fits.gz file does not exist; skipping the attachment.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 10 Aug 07 02:26:09 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     287364,   Seg_Num: 0
POINT_RA:        189.973d {+12h 39m 54s} (J2000)
POINT_DEC:       +10.736d {+10d 44' 10"} (J2000)
POINT_ROLL:      281.583d
IMG_START_DATE:  14322 TJD;   222 DOY;   07/08/10
IMG_START_TIME:  8109.92 SOD {02:15:09.92} UT,   24772.6 [sec] since BAT Trigger Time
FILTER:          3, V
BKG_MEAN:        3.309
N_STARS:         14
X_OFFSET:        702 [pixels]
Y_OFFSET:        443 [pixels]
X_MAX:           1661 [pixels]
Y_MAX:           1402 [pixels]
DET_THRESH:      15
PHOTO_THRESH:    8
SL_URL:          sw00287364000msufc24772.fits
SUN_POSTN:       139.56d {+09h 18m 15s}  +15.71d {+15d 42' 21"}
SUN_DIST:         49.32 [deg]   Sun_angle= -3.4 [hr] (East of Sun)
MOON_POSTN:      103.23d {+06h 52m 54s}  +27.20d {+27d 11' 53"}
MOON_DIST:        82.36 [deg]
MOON_ILLUM:      9 [%]
GAL_COORDS:      292.97, 73.38 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      184.84, 13.80 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 10 Aug 07 02:26:36 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     287364,   Seg_Num: 0
POINT_RA:        189.973d {+12h 39m 54s} (J2000)
POINT_DEC:       +10.736d {+10d 44' 10"} (J2000)
POINT_ROLL:      281.583d
IMG_START_DATE:  14322 TJD;   222 DOY;   07/08/10
IMG_START_TIME:  8109.92 SOD {02:15:09.92} UT,   24772.6 [sec] since BAT Trigger Time
FILTER:          3, V
BKG_MEAN:        3.309
N_STARS:         14
X_OFFSET:        702 [pixels]
Y_OFFSET:        443 [pixels]
X_MAX:           1661 [pixels]
Y_MAX:           1402 [pixels]
DET_THRESH:      15
PHOTO_THRESH:    8
SL_URL:          sw00287364000msufc24772.fits
SUN_POSTN:       139.56d {+09h 18m 15s}  +15.71d {+15d 42' 21"}
SUN_DIST:         49.32 [deg]   Sun_angle= -3.4 [hr] (East of Sun)
MOON_POSTN:      103.23d {+06h 52m 55s}  +27.20d {+27d 11' 50"}
MOON_DIST:        82.36 [deg]
MOON_ILLUM:      9 [%]
GAL_COORDS:      292.97, 73.38 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      184.84, 13.80 [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:     Fri 10 Aug 07 02:27:35 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     287364,   Seg_Num: 0
POINT_RA:        189.973d {+12h 39m 54s} (J2000)
POINT_DEC:       +10.736d {+10d 44' 10"} (J2000)
ROLL:            281.583d
IMG_START_DATE:  14322 TJD;   222 DOY;   07/08/10
IMG_START_TIME:  8109.92 SOD {02:15:09.92} UT,   24772.6 [sec] since BAT Trigger Time
FILTER:          3, V
EXPOSURE_ID:     208404912
X_OFFSET:        1021 [pixels]
Y_OFFSET:        762 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1181
Y_GRB_POS:       922
BINNING_INDEX:   1
IM_URL:          sw00287364000msuni24772.fits
SUN_POSTN:       139.56d {+09h 18m 15s}  +15.71d {+15d 42' 20"}
SUN_DIST:         49.32 [deg]   Sun_angle= -3.4 [hr] (East of Sun)
MOON_POSTN:      103.24d {+06h 52m 58s}  +27.20d {+27d 11' 46"}
MOON_DIST:        82.35 [deg]
MOON_ILLUM:      9 [%]
GAL_COORDS:      292.97, 73.38 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      184.84, 13.80 [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:     Fri 10 Aug 07 02:27:52 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     287364,   Seg_Num: 0
POINT_RA:        189.973d {+12h 39m 54s} (J2000)
POINT_DEC:       +10.736d {+10d 44' 10"} (J2000)
ROLL:            281.583d
IMG_START_DATE:  14322 TJD;   222 DOY;   07/08/10
IMG_START_TIME:  8109.92 SOD {02:15:09.92} UT,   24772.6 [sec] since BAT Trigger Time
FILTER:          3, V
EXPOSURE_ID:     208404912
X_OFFSET:        1021 [pixels]
Y_OFFSET:        762 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1181
Y_GRB_POS:       922
BINNING_INDEX:   1
IM_URL:          sw00287364000msuni24772.fits
SUN_POSTN:       139.56d {+09h 18m 15s}  +15.71d {+15d 42' 20"}
SUN_DIST:         49.32 [deg]   Sun_angle= -3.4 [hr] (East of Sun)
MOON_POSTN:      103.24d {+06h 52m 58s}  +27.20d {+27d 11' 44"}
MOON_DIST:        82.35 [deg]
MOON_ILLUM:      9 [%]
GAL_COORDS:      292.97, 73.38 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      184.84, 13.80 [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:        If you have elected to receive attachments:  
COMMENTS:        The uvot_sources_image.fits.gz file does not exist; skipping the attachment.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 10 Aug 07 02:33:08 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     287364,   Seg_Num: 0
GRB_RA:          189.9628d {+12h 39m 51.0s} (J2000),
                 190.0588d {+12h 40m 14.1s} (current),
                 189.3313d {+12h 37m 19.5s} (1950)
GRB_DEC:         +10.7513d {+10d 45' 04.6"} (J2000),
                 +10.7096d {+10d 42' 34.5"} (current),
                 +11.0258d {+11d 01' 32.7"} (1950)
GRB_ERROR:       3.6 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      5.00 [sigma]
IMG_START_DATE:  14322 TJD;   222 DOY;   07/08/10
IMG_START_TIME:  8000.15 SOD {02:13:20.15} UT,   24662.8 [sec] since BAT Trigger Time
TAM[0-3]:        327.61 237.19 261.35 242.66
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       139.57d {+09h 18m 16s}  +15.70d {+15d 42' 16"}
SUN_DIST:         49.30 [deg]   Sun_angle= -3.4 [hr] (East of Sun)
MOON_POSTN:      103.30d {+06h 53m 12s}  +27.19d {+27d 11' 18"}
MOON_DIST:        82.28 [deg]
MOON_ILLUM:      9 [%]
GAL_COORDS:      292.93, 73.40 [deg] galactic lon,lat of the burst
ECL_COORDS:      184.83, 13.81 [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 Circular #6733
J. R. Cummings (NASA/UMBC), S. D. Barthelmy (GSFC), M. M. Chester (PSU), N. Gehrels (NASA/GSFC), S. T. Holland (CRESST/GSFC/USRA), J. A. Kennea (PSU), C. B. Markwardt (CRESST/GSFC/UMD), D. M. Palmer (LANL) and M. Stamatikos (NASA/ORAU) report on behalf of the Swift Team:
At 02:11:52 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 070810 (trigger=287364). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 189.939, +10.744 which is
```
   RA(J2000)  =  12h 39m 45s
   Dec(J2000) = +10d 44' 40"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single peak structure with a duration of about 20 sec. The peak count rate was ~2500 counts/sec (15-350 keV), at T+0 sec after the trigger.
The XRT began taking data at 02:13:20 UT, 88 seconds after the BAT trigger. The XRT on-board centroid algorithm did not find a source in the image. Using prompt downlinked data, we find a fading, X-ray source located at RA, Dec 189.9629, 10.7513 which is
```
   RA(J2000)  =  12 39 51.10
   Dec(J2000) = +10 45 04.7
```
with an uncertainty of 3.9 arcsec (radius, 90% containment). This position is 89 arcminutes from the BAT position.
UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm) filter starting 92 seconds after the BAT trigger, and a finding chart exposure of a nominal 400 seconds starting 198 seconds. A possible candidate has been identified visually in the initial data products, but processing is still underway so no position or significance is available at this time. The 2.7' x 2.7' sub-image does not cover the XRT error circle; the 8' x 8' list of sources covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 18.5 mag.
No BAT_Position Notice was distributed, because none was received from the TDRSS system. This burst occurred during a 24-sec gap in TDRSS coverage due to a hand-off from one TDRSS satellite to the next satellite, so none of the initial notices were available (BAT_Position, FOM, and SC_Slew).
Burst Advocate for this burst is J. R. Cummings (jayc AT milkyway.gsfc.nasa.gov). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html)
GCN Circular #6734
H. Swan (U Mich), B. E. Schaefer (Louisiana State), E.S. Rykoff (U Mich), report on behalf of the ROTSE collaboration:
ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 070810 (Swift trigger 287364). The first image was at 02:34:02.5 UT, 1330.5 s after the burst. The unfiltered images are calibrated relative to USNO A2.0. We detect a 16.7 magnitude, fading source with coordinates:
12:39:51.48 +10:45:00.90 (J2000).
The source is blended with a nearby USNO star visible in the DSS, and thus our initial positional uncertainty is ~3".
```
start UT    	mag     mlim(of image)
----------------------------------
02:29:53.4     16.7     18.5
```
This source is not visible in DSS (second epoch), 2MASS or the MPChecker database.
A jpeg image is available at http://www.rotse.net/images/gsb0174_3b01_img.jpg
Continuing observations are in progress.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 10 Aug 07 03:45:00 UT
NOTICE_TYPE:     Swift-UVOT Position
TRIGGER_NUM:     287364,   Seg_Num: 0
GRB_RA:          189.9633d {+12h 39m 51.19s} (J2000),
                 190.0593d {+12h 40m 14.24s} (current),
                 189.3318d {+12h 37m 19.62s} (1950)
GRB_DEC:         +10.7515d {+10d 45' 05.4"} (J2000),
                 +10.7098d {+10d 42' 35.3"} (current),
                 +11.0260d {+11d 01' 33.4"} (1950)
GRB_ERROR:       0.7 [arcsec radius, statistical only]
GRB_MAG:         17.39 +/- 0.10 [mag]
FILTER:          10, White
IMG_START_DATE:  14322 TJD;   222 DOY;   07/08/10
IMG_START_TIME:  8003.93 SOD {02:13:23.93} UT,   24666.6 [sec] since BAT Trigger Time
SUN_POSTN:       139.62d {+09h 18m 28s}  +15.69d {+15d 41' 24"}
SUN_DIST:         49.26 [deg]   Sun_angle= -3.4 [hr] (East of Sun)
MOON_POSTN:      104.05d {+06h 56m 12s}  +27.09d {+27d 05' 15"}
MOON_DIST:        81.63 [deg]
MOON_ILLUM:      9 [%]
GAL_COORDS:      292.93, 73.40 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      184.83, 13.81 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT UVOT Position Notice.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.

GCN Circular #6735
M.M. Chester (PSU), F.E. Marshall (NASA/GSFC), and J.R. Cummings (NASA/UMBC) report on behalf of the Swift UVOT team:
The Swift/UVOT observed the field of GRB 070810 (Cummings et al., GCN Circ. 6733) beginning 02:13:24 UT, 92 seconds after the BAT trigger.
We find an uncatalogued source inside the Swift/XRT error circle in the initial 2.7' x 2.7' subimage in the White filter at:
```
    RA(J2000)  = 12:39:51.22 = 189.9634
    DEC(J2000) = +10:45:04.3  = 10.7512
```
with a 1-sigma error radius of about 0.6 arc sec. This position is 1.9 arcsec from the center of the XRT error circle, and 5.0 arcsec from the position reported by ROTSE (Swan et al. GCN Circ. 6734). The counterpart is not blended in the Swift/UVOT images. The estimated magnitudes (1-sigma error is about 1 mag) are:
```
Filter   Tstart    Exp     Magnitude
            (s)     (s)
White      92      100       17.4
v         198      306       17.1
```
The values quoted above are not corrected for the expected Galactic extinction corresponding to a reddening of E_{B-V} = 0.02 mag in the direction of the burst (Schlegel et al. 1998).
GCN Circular #6736
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team.
Using 505 s of overlapping XRT Photon Counting mode and UVOT V-band data for GRB 070810, 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 = 189.96368, +10.75080 which is equivalent to:
```
RA (J2000): 12d 39' 51.28"
Dec (J2000): +10h 45m 02.9s
```
with an uncertainty of 1.9 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, astro-ph/0708.0986 http://www.swift.ac.uk/xrt_positions/Goad.pdf.)
This circular was automatically generated, and is an official product of the Swift-XRT team.
GCN Circular #6738
K.L. Page, P.A. Evans (U. Leicester), M.M Chester (PSU) and J.R. Cummings (NASA/UMBC) report on behalf of the Swift-XRT team:
We have analysed the first four orbits of Swift-XRT data obtained for GRB 070810 (Cummings et al., GCN Circ. 6733), totalling 7.9 ks of Photon Counting (PC) mode data. The enhanced XRT position was given by Evans et al. in GCN Circ. 6736, and is 1.7 arcsec from the fading UVOT source (Chester et al., GCN Circ. 6735).
The X-ray light-curve is almost flat for the first orbit of PC data, with alpha = 0.30 +0.18/-0.20. About 1.1 ks after the trigger, the decay steepened to a slope of 1.1 +/- 0.2.
Fitting the PC data from the second to fourth orbits (i.e. after the break; 3.8-17.8 ks after the trigger), the spectrum can be modelled by an absorbed power-law with Gamma = 2.3 +/- 0.3 and NH = (1.3 +/- 0.5)e21 cm^-2, in excess of the Galactic value of 1.75e20 cm^-2. The 0.3-10 keV observed (unabsorbed) flux during this time is 2.17e-12 (3.34e-12) erg cm^-2 s^-1.
If the decay continues with a slope of alpha ~ 1.1, the predicted count rate at 24 hours is 4.1e-3 count s^-1. Using a flux conversion factor (determined from the post-break spectrum described above) of 1 count s^-1 ~ 4e-11 erg cm^-2 s^-1 (observed) and 5.8e-11 erg cm^-2 s^-1 (unabsorbed), this corresponds to an observed (unabsorbed) flux of 1.6e-13 (2.4e-13) erg cm^-2 s^-1.
This circular is an official product of the Swift-XRT team.
GCN Circular #6741
C. C. Thoene (DARK, UC Berkeley), D. A. Perley (UCB), J. Cooke (UC Irvine), J. S. Bloom (UC Berkeley), H.-W. Chen (Univ. Chicago) and E. Barton (UCI) report:
We took 2x10min spectra of the afterglow of GRB 070810 (GCN 6734, Swan et al.; GCN 6735, Chester et al.) with Keck I + LRIS on Aug. 10, starting 05:46:32 UT (3.58h after the burst) in twilight. From a DLA and several absorption lines including Fe II, OI, SiII and CII, we infer a redshift of z=2.17 for that burst.
In addition, we obtained 2x120 s imaging in R band and 2x150 s in g band, starting at 06:13:26 UT. Calibrating relative to five USNO-B1.0 stars, we measure a magnitude of R=20.45 +/- 0.5, dominated by the systematic uncertainty relative to the catalog.
GCN Circular #6748
C. Markwardt (GSFC/UMD), L. Barbier (GSFC), S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. Ukwatta (GWU)
Using the data set from T-240 to T+804 sec from the recent telemetry downlink, we report further analysis of BAT GRB 070810A (trigger #287364) (Cummings, et al., GCN Circ. 6733). The BAT ground-calculated position is RA, Dec = 189.947, 10.747 deg which is
```
   RA(J2000) = 12h 39m 47.2s 
   Dec(J2000) = 10d 44' 48" 
```
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment). This is 1.0 arcmin from the optical and refined XRT positions (Chester et al. GCN circ. 6735 and Evans et al. GCN circ. 6736). The partial coding was 53%.
The mask-weighted light curve shows a single peak with softening spectral evolution. T90 (15-350 keV) is 11.0 +- 1 sec (estimated error including systematics).
The time-averaged spectrum from T-3.1 to T+14.3 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.04 +- 0.14. The fluence in the 15-150 keV band is 6.9 +- 0.6 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T-0.11 sec in the 15-150 keV band is 1.9 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
GCN Circular #6750
V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, E.Gorbovskoy, A.Krylov, N.Shatskiy, N.Tyurina,G.Borisov, A.Sankovich, V.Vladimirov, O.S.Shvartsman Sternberg Astronomical Institute, Moscow Union 'Optic'
I.Zalozhnih Ural State University
Sternberg Astronomical Institute, Moscow Union 'Optic' MASTER robotic system (http://observ.pereplet.ru) responded to GRB070810.8 (GRB_TIME is 2007-08-10 19:54:05.85). The first image was at 2007-08-10 19:56:11 UT, 125.15 after the GRB time The unfiltered image is calibrated relative to USNO A2.0 (0.8 R + 0.2 B). The robot not find OT-candidate in error box brighter then 14.8 (s/n=10). The JPG-image will be available at http://observ.pereplet.ru/images/GRB070810.8/img/i12.jpg 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 #6752
V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, E.Gorbovskoy, A.Krylov, N.Shatskiy, N.Tyurina,G.Borisov, A.Sankovich, V.Vladimirov, O.S.Shvartsman Sternberg Astronomical Institute, Moscow Union 'Optic'
I.Zalozhnih Ural State University
Sternberg Astronomical Institute, Moscow Union 'Optic' MASTER robotic system (http://observ.pereplet.ru) responded to GRB070810.8 (GRB_TIME is 2007-08-10 19:54:05.85). The first image was at 2007-08-10 19:56:11 UT, 125.15 after the GRB time The unfiltered image is calibrated relative to USNO A2.0 (0.8 R + 0.2 B). The robot not find OT-candidate in error box brighter then 14.8 (s/n=10). The JPG-image will be available at http://observ.pereplet.ru/images/GRB070810.8/img/i12.jpg 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 #6757
D. A. Perley, J. S. Bloom (UC Berkeley), and C. C. Thoene (DARK, UCB) report:
Beginning at 06:48:00 UT (2007-08-11) we began a second series of imaging exposures on the field of GRB 070810A (GCN 7433) using the Keck I telescope (+LRIS). We acquired a total of 390s in R band and 480s in g band through high airmass.
The optical afterglow (GCN 6734) is still detected, but has faded significantly since our previous imaging epoch (GCN 6741) and appears marginally extended. Aperture photometry of the source indicates that it has has faded by 3.2 +/- 0.1 magnitudes since the observations the first night, corresponding to a decay index of alpha >= 1.5 between 4 hours and 28.6 hours including a possible contribution from a host galaxy or other extended source.
Using the same calibration system as in our previous circular, we estimate a preliminary magnitude of R=23.7.
GCN Circular #6761
F. Yuan, E.S. Rykoff (U Mich), report on behalf of the ROTSE collaboration:
ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 070810A (Swift trigger 287364; Cummings, et al., GCN 6733), and detected the optical counterpart (Swan, et al., GCN 6734). The initial aperture photometry reported in GCN 6734 was biased due to contamination from the nearby star. With a reference image taken 6 days after the burst, we were able to subtract the nearby star and obtain better estimate of the OT brightness with PSF fitting. Our refined analysis shows the OT at 18.0 =B1 0.2 mag (unfiltered images, calibrated relative to USNO-B1.0 R) between 1607s and 2290s after the burst.
```
start UT       end UT        mag
-------------------------------------
02:38:39.5   02:50:02.3    18.0+/-0.2
03:13:15.7   03:24:39.0    18.5+/-0.2
```
The OT faded with a decay index 0.7 =B10.2 in the next 40 minutes before dropping below our detection threshold. This decay index is significantly shallower than seen at later time in Keck photometry (Perley, et al., GCN 6757), implying a light curve break between 1.2 hr and 4 hr after the burst.

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Jochen Greiner, last update: 17-Aug-2007 [Disclaimer]