Gamma-ray Burst 110820A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 20 Aug 11 17:39:00 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     501095,   Seg_Num: 0
GRB_RA:          343.335d {+22h 53m 20s} (J2000),
                 343.433d {+22h 53m 44s} (current),
                 342.919d {+22h 51m 41s} (1950)
GRB_DEC:         +70.305d {+70d 18' 20"} (J2000),
                 +70.368d {+70d 22' 03"} (current),
                 +70.039d {+70d 02' 21"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       9006 [cnts]    Image_Peak=275 [image_cnts]
TRIGGER_DUR:     2.048 [sec] 
TRIGGER_INDEX:   262     E_range: 25-100 keV
BKG_INTEN:       89794 [cnts]
BKG_TIME:        63472.71 SOD {17:37:52.71} UT
BKG_DUR:         24 [sec]
GRB_DATE:        15793 TJD;   232 DOY;   11/08/20
GRB_TIME:        63507.79 SOD {17:38:27.79} UT
GRB_PHI:         -117.71 [deg]
GRB_THETA:        11.48 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     12.52 [sigma]
IMAGE_SIGNIF:    8.09 [sigma]
MERIT_PARAMS:     +1  +0  +0  +1  +2  -2  +0  +1 +11  +0 
SUN_POSTN:       149.56d {+09h 58m 14s}  +12.39d {+12d 23' 16"}
SUN_DIST:         96.69 [deg]   Sun_angle= 11.1 [hr] (West of Sun)
MOON_POSTN:       40.93d {+02h 43m 44s}  +19.00d {+19d 00' 15"}
MOON_DIST:        61.48 [deg]
MOON_ILLUM:      61 [%]
GAL_COORDS:      113.23,  9.69 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       41.52, 64.46 [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 = 41.74,14.70 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 20 Aug 11 17:40:10 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     501095,   Seg_Num: 0
POINT_RA:        343.329d {+22h 53m 19s} (J2000)
POINT_DEC:       +70.310d {+70d 18' 35"} (J2000)
IMG_START_DATE:  15793 TJD;   232 DOY;   11/08/20
IMG_START_TIME:  63586.83 SOD {17:39:46.83} UT,   79.0 [sec] since BAT Trigger Time
COUNTS:          34    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        4    Max_iter_allowed= 4
ERROR_CODE:      2
COMMENTS:        SWIFT-XRT Nack Position.  
COMMENTS:        Algorithm did not converge; too many iterations.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 20 Aug 11 17:42:19 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     501095,   Seg_Num: 0
GRB_RA:          343.335d {+22h 53m 20s} (J2000),
                 343.433d {+22h 53m 44s} (current),
                 342.919d {+22h 51m 41s} (1950)
GRB_DEC:         +70.305d {+70d 18' 20"} (J2000),
                 +70.368d {+70d 22' 03"} (current),
                 +70.039d {+70d 02' 21"} (1950)
GRB_DATE:        15793 TJD;   232 DOY;   11/08/20
GRB_TIME:        63507.79 SOD {17:38:27.79} UT
TRIGGER_INDEX:   262
GRB_PHI:         -117.71 [deg]
GRB_THETA:        11.48 [deg]
DELTA_TIME:      12.00 [sec]
TRIGGER_DUR:     2.048 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     12.52 [sigma]
IMAGE_SIGNIF:    8.09 [sigma]
LC_URL:          sw00501095000msb.lc
SUN_POSTN:       149.56d {+09h 58m 15s}  +12.39d {+12d 23' 13"}
SUN_DIST:         96.69 [deg]   Sun_angle= 11.1 [hr] (West of Sun)
MOON_POSTN:       40.96d {+02h 43m 50s}  +19.01d {+19d 00' 38"}
MOON_DIST:        61.49 [deg]
MOON_ILLUM:      61 [%]
GAL_COORDS:      113.23,  9.69 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       41.52, 64.46 [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 = 41.74,14.70 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 20 Aug 11 17:44:04 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     501095,   Seg_Num: 0
GRB_RA:          343.1935d {+22h 52m 46.43s} (J2000),
                 343.2903d {+22h 53m 09.67s} (current),
                 342.7788d {+22h 51m 06.91s} (1950)
GRB_DEC:         +70.2974d {+70d 17' 50.6"} (J2000),
                 +70.3594d {+70d 21' 33.9"} (current),
                 +70.0312d {+70d 01' 52.2"} (1950)
GRB_ERROR:       4.5 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  15793 TJD;   232 DOY;   11/08/20
IMG_START_TIME:  63598.00 SOD {17:39:58.00} UT,   90.2 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       149.56d {+09h 58m 15s}  +12.39d {+12d 23' 12"}
SUN_DIST:         96.71 [deg]   Sun_angle= 11.1 [hr] (West of Sun)
MOON_POSTN:       40.97d {+02h 43m 54s}  +19.01d {+19d 00' 50"}
MOON_DIST:        61.53 [deg]
MOON_ILLUM:      61 [%]
GAL_COORDS:      113.19,  9.70 [deg] galactic lon,lat of the burst
ECL_COORDS:       41.45, 64.49 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.58% < P(seren) < 1.1%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 20 Aug 11 17:45:24 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     501095,   Seg_Num: 0
POINT_RA:        343.331d {+22h 53m 19s} (J2000)
POINT_DEC:       +70.307d {+70d 18' 26"} (J2000)
POINT_ROLL:      13.551d
IMG_START_DATE:  15793 TJD;   232 DOY;   11/08/20
IMG_START_TIME:  63647.01 SOD {17:40:47.01} UT,   139.2 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.606
N_STARS:         190
X_OFFSET:        234 [pixels]
Y_OFFSET:        333 [pixels]
X_MAX:           1673 [pixels]
Y_MAX:           1772 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw00501095000msufc0139.fits
SUN_POSTN:       149.56d {+09h 58m 15s}  +12.39d {+12d 23' 11"}
SUN_DIST:         96.69 [deg]   Sun_angle= 11.1 [hr] (West of Sun)
MOON_POSTN:       40.99d {+02h 43m 57s}  +19.02d {+19d 00' 59"}
MOON_DIST:        61.49 [deg]
MOON_ILLUM:      61 [%]
GAL_COORDS:      113.23,  9.69 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       41.52, 64.46 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 20 Aug 11 17:46:09 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     501095,   Seg_Num: 0
GRB_RA:          343.1911d {+22h 52m 45.86s} (J2000),
                 343.2879d {+22h 53m 09.09s} (current),
                 342.7764d {+22h 51m 06.34s} (1950)
GRB_DEC:         +70.2968d {+70d 17' 48.4"} (J2000),
                 +70.3588d {+70d 21' 31.7"} (current),
                 +70.0306d {+70d 01' 50.1"} (1950)
GRB_ERROR:       3.4 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  15793 TJD;   232 DOY;   11/08/20
IMG_START_TIME:  63598.00 SOD {17:39:58.00} UT,   90.2 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       149.56d {+09h 58m 15s}  +12.39d {+12d 23' 10"}
SUN_DIST:         96.71 [deg]   Sun_angle= 11.1 [hr] (West of Sun)
MOON_POSTN:       40.99d {+02h 43m 58s}  +19.02d {+19d 01' 04"}
MOON_DIST:        61.53 [deg]
MOON_ILLUM:      61 [%]
GAL_COORDS:      113.18,  9.70 [deg] galactic lon,lat of the burst
ECL_COORDS:       41.45, 64.49 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        This is an Update Notice -- the RA,Dec values herein supersede the previous XRT_POS Notice.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        This position was enhanced using UVOT field astrometry.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.58% < P(seren) < 1.1%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 20 Aug 11 17:49:22 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     501095,   Seg_Num: 0
POINT_RA:        343.331d {+22h 53m 19s} (J2000)
POINT_DEC:       +70.307d {+70d 18' 26"} (J2000)
ROLL:            13.551d
IMG_START_DATE:  15793 TJD;   232 DOY;   11/08/20
IMG_START_TIME:  63647.01 SOD {17:40:47.01} UT,   139.2 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     335554854
X_OFFSET:        793 [pixels]
Y_OFFSET:        892 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       953
Y_GRB_POS:       1052
BINNING_INDEX:   1
IM_URL:          sw00501095000msuni0147.fits
SUN_POSTN:       149.57d {+09h 58m 16s}  +12.39d {+12d 23' 08"}
SUN_DIST:         96.69 [deg]   Sun_angle= 11.1 [hr] (West of Sun)
MOON_POSTN:       41.02d {+02h 44m 05s}  +19.02d {+19d 01' 27"}
MOON_DIST:        61.49 [deg]
MOON_ILLUM:      61 [%]
GAL_COORDS:      113.23,  9.69 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       41.52, 64.46 [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:     Sat 20 Aug 11 17:49:46 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     501095,   Seg_Num: 0
POINT_RA:        343.331d {+22h 53m 19s} (J2000)
POINT_DEC:       +70.307d {+70d 18' 26"} (J2000)
ROLL:            13.551d
IMG_START_DATE:  15793 TJD;   232 DOY;   11/08/20
IMG_START_TIME:  63647.01 SOD {17:40:47.01} UT,   139.2 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     335554854
X_OFFSET:        793 [pixels]
Y_OFFSET:        892 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       953
Y_GRB_POS:       1052
BINNING_INDEX:   1
IM_URL:          sw00501095000msuni0147.fits
SUN_POSTN:       149.57d {+09h 58m 16s}  +12.39d {+12d 23' 07"}
SUN_DIST:         96.69 [deg]   Sun_angle= 11.1 [hr] (West of Sun)
MOON_POSTN:       41.02d {+02h 44m 06s}  +19.02d {+19d 01' 29"}
MOON_DIST:        61.49 [deg]
MOON_ILLUM:      61 [%]
GAL_COORDS:      113.23,  9.69 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       41.52, 64.46 [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 #12288
E. Troja (NASA/GSFC/ORAU), S. D. Barthelmy (GSFC), J. R. Cummings (NASA/UMBC), V. D'Elia (ASDC), P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL), C. B. Markwardt (NASA/GSFC), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester), B. Sbarufatti (INAF-OAB/IASFPA), M. H. Siegel (PSU), E. Sonbas (GSFC/USRA/Adiyaman Univ.) and T. N. Ukwatta (MSU) report on behalf of the Swift Team:
At 17:38:27 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 110820A (trigger=501095). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 343.335, +70.305 which is
```
   RA(J2000) = 22h 53m 20s
   Dec(J2000) = +70d 18' 20"
```
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 10 sec. The peak count rate was ~2000 counts/sec (15-350 keV), at ~1 sec after the trigger.
The XRT began observing the field at 17:39:46.8 UT, 79.0 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 343.1911, 70.2974 which is equivalent to:
```
   RA(J2000)  = 22h 52m 45.86s
   Dec(J2000) = +70d 17' 50.5"
```
with an uncertainty of 2.3 arcseconds (radius, 90% containment). This location is 177 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper. We cannot determine whether the source is fading at the present time.
A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 3.34 x 10^21 cm^-2 (Kalberla et al. 2005).
UVOT took a finding chart exposure of 250 seconds with the U filter starting 139 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers none of the XRT error circle. Data from the list of sources generated on-board are not available at this time. No correction has been made for the expected extinction corresponding to E(B-V) of 0.55.
Burst Advocate for this burst is E. Troja (eleonora.troja AT 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 NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 20 Aug 11 17:56:42 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     501095,   Seg_Num: 0
POINT_RA:        343.330d {+22h 53m 19s} (J2000)
POINT_DEC:       +70.308d {+70d 18' 27"} (J2000)
POINT_ROLL:      13.550d
IMG_START_DATE:  15793 TJD;   232 DOY;   11/08/20
IMG_START_TIME:  64377.02 SOD {17:52:57.02} UT,   869.2 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.358
N_STARS:         190
X_OFFSET:        234 [pixels]
Y_OFFSET:        333 [pixels]
X_MAX:           1673 [pixels]
Y_MAX:           1772 [pixels]
DET_THRESH:      6
PHOTO_THRESH:    2
SL_URL:          sw00501095000msufc0869.fits
SUN_POSTN:       149.57d {+09h 58m 17s}  +12.38d {+12d 23' 02"}
SUN_DIST:         96.70 [deg]   Sun_angle= 11.1 [hr] (West of Sun)
MOON_POSTN:       41.08d {+02h 44m 20s}  +19.04d {+19d 02' 17"}
MOON_DIST:        61.50 [deg]
MOON_ILLUM:      61 [%]
GAL_COORDS:      113.23,  9.69 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       41.52, 64.46 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 20 Aug 11 17:57:54 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     501095,   Seg_Num: 0
POINT_RA:        343.330d {+22h 53m 19s} (J2000)
POINT_DEC:       +70.308d {+70d 18' 27"} (J2000)
ROLL:            13.550d
IMG_START_DATE:  15793 TJD;   232 DOY;   11/08/20
IMG_START_TIME:  64377.02 SOD {17:52:57.02} UT,   869.2 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     335555584
X_OFFSET:        793 [pixels]
Y_OFFSET:        892 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       953
Y_GRB_POS:       1052
BINNING_INDEX:   1
IM_URL:          sw00501095000msuni0877.fits
SUN_POSTN:       149.57d {+09h 58m 17s}  +12.38d {+12d 23' 01"}
SUN_DIST:         96.70 [deg]   Sun_angle= 11.1 [hr] (West of Sun)
MOON_POSTN:       41.09d {+02h 44m 22s}  +19.04d {+19d 02' 25"}
MOON_DIST:        61.50 [deg]
MOON_ILLUM:      61 [%]
GAL_COORDS:      113.23,  9.69 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       41.52, 64.46 [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:     Sat 20 Aug 11 17:58:04 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     501095,   Seg_Num: 0
POINT_RA:        343.330d {+22h 53m 19s} (J2000)
POINT_DEC:       +70.308d {+70d 18' 27"} (J2000)
ROLL:            13.550d
IMG_START_DATE:  15793 TJD;   232 DOY;   11/08/20
IMG_START_TIME:  64377.02 SOD {17:52:57.02} UT,   869.2 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     335555584
X_OFFSET:        793 [pixels]
Y_OFFSET:        892 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       953
Y_GRB_POS:       1052
BINNING_INDEX:   1
IM_URL:          sw00501095000msuni0877.fits
SUN_POSTN:       149.57d {+09h 58m 17s}  +12.38d {+12d 23' 00"}
SUN_DIST:         96.70 [deg]   Sun_angle= 11.1 [hr] (West of Sun)
MOON_POSTN:       41.09d {+02h 44m 23s}  +19.04d {+19d 02' 26"}
MOON_DIST:        61.50 [deg]
MOON_ILLUM:      61 [%]
GAL_COORDS:      113.23,  9.69 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       41.52, 64.46 [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 #12289
K.Ivanov, V.A.Poleshchuk, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev,E.Konstantinov, Irkutsk State University
E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, N.Tyurina, N.Shatskiy, P.Balanutsa, V.V.Chazov, P.V.Kortunov, A.Kuznetsov, D.Zimnukhov, M. Kornilov, A.Kuznetsov, D.Zimnukhov, M. Kornilov, A.Sankovich Sternberg Astronomical Institute, Moscow State University
A. Tlatov, A.V. Parhomenko, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory
V.Krushinski, I.Zalozhnich, T.Kopytova, A. Popov Ural State University, Kourovka
V.Yurkov, Yu.Sergienko, D.Varda, I.Kudelina Blagoveschensk Educational State University, Blagoveschensk
MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Tunka(Siberia) was pointed to the GRB110820A 45 sec after notice time and 133 sec after GRB time at 2011-08-20 17:40:40.275 UT in two polarizations. On our first (30s exposure) set we haven`t found optical transient within SWIFT error-box.
The 5-sigma upper limit has been about 16.5 mag The message may be cited.
GCN Circular #12290
V. Rumyantsev, K. Antoniuk (CrAO), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:
We observed the field of the Swift GRB 110820A (Troja et al., GCN 12288) with AZT-11 telescope of CrAO between Aug. 20 (UT) 18:23 - 19:21. Within the XRT error box (Troja et al., GCN 12288) we do not detect any source. The photometry is based on the USNO B1.0 star 1602-0161058 (22:52:45.06 +70:17:17.5) assuming R=18.23:
```
T0+      Filter,   Exposure, OT,           Upper Limit (3 sigma)
(mid, d)              (s)

0.0520   R        20x180       n/d           21.6
```
GCN Circular #12291
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team.
Using 1200 s of XRT Photon Counting mode data and 2 UVOT images for GRB 110820A, 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 = 343.19224, +70.29848 which is equivalent to:
```
RA (J2000): 22h 52m 46.14s
Dec (J2000): +70d 17' 54.5"
```
with an uncertainty of 2.3 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177).
This circular was automatically generated, and is an official product of the Swift-XRT team.
GCN Circular #12292
D. M. Palmer (LANL), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), T. Sakamoto (GSFC/UMBC), M. Stamatikos (OSU), E. Troja (NASA/GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team):
Using the data set from T-119 to T+296 sec from recent telemetry downlinks, we report further analysis of BAT GRB 110820A (trigger #501095) (Troja, et al., GCN Circ. 12288). The BAT ground-calculated position is RA, Dec = 343.203, 70.298 deg, which is
```
   RA(J2000)  =  22h 52m 48.8s 
   Dec(J2000) = +70d 17' 51.2" 
```
with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 99%.
The mask-weighted light curve shows two main peaks. The first started at ~T-5 sec, peaking at ~T+2 sec, and ending at ~T+35 sec. The second starts at ~T+195 sec, peaking at ~T+230, and ending at ~T+285 sec. T90 (15-350 keV) is 256 +- 50 sec (estimated error including systematics).
The time-averaged spectrum from T-7.07 to T+264.9 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.92 +- 0.28. The fluence in the 15-150 keV band is 8.2 +- 1.5 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+0.43 sec in the 15-150 keV band is 0.4 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/501095/BA/
GCN Circular #12293
D. Kuroda (OAO, NAOJ), H. Hanayama, T. Miyaji, J. Watanabe (IAO, NAOJ), K. Yanagisawa (OAO, NAOJ), S.Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto) and N. Kawai(Tokyo Tech) report on behalf of the MITSuME collaboration:
We observed the field of GRB 110820A (Troja et al., GCNC 12288) with the optical three color (g', Rc and Ic) CCD camera attached to the Murikabushi 1m telescope of Ishigakijima Astronomical Observatory.
The observation started on 17:47:41 UT (~9 min after the burst). We did not find any new point source within the enhanced XRT error circle (Beardmore et al., GCNC 12291) in all the three bands.
Three sigma upper limits of the OT are listed below. We used GSC2.3 catalog for flux calibration.
```
#T0+[day]  MID-UT    T-EXP[sec]   g'    Rc    Ic
----------------------------------------------------
0.04719    18:46:24    5280.0   >20.6 >21.3 >19.9
----------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]
```
GCN Circular #12294
K.L. Page (U. Leicester) and E. Troja (NASA/GSFC/ORAU) report on behalf of the Swift-XRT team:
We have analysed 10 ks of XRT data for GRB 110820A (Troja et al. GCN Circ. 12288), from 82 s to 24.5 ks after the BAT trigger. The data comprise 121 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN. Circ 12291).
The first snapshot of data is dominated by a large flare, also detected by the BAT (Palmer et al. GCN Circ. 12292). After around 750 s, the light curve decay can be fitted with index alpha=0.28 (+0.13, -0.15).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.32 (+0.07, -0.06). The best-fitting absorption column is 6.1 (+/-0.5) x 10^21 cm^-2, in excess of the Galactic value of 3.3 x 10^21 cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a photon index of 1.80 (+0.20, -0.26) and a best-fitting absorption column of 4.7 (+/-1.3) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 5.1 x 10^-11 (7.8 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     4.7 (+/-1.3) x 10^21 cm^-2
Galactic foreground: 3.3 x 10^21 cm^-2
Excess significance: 5.9 sigma
Photon index:	     1.80 (+0.20, -0.26)
```
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00501095.
This circular is an official product of the Swift-XRT team.
GCN Circular #12295
Myungshin Im, Won-Kee Park (CEOU/Seoul National Univ), Soojong Pak, Giseon Baek, and Youngseok Oh (Kyunghee University)
We observed GRB 100820A (Troja et al. GCN 12288) with i,z,and Y-filters using CQUEAN camera (the Camera for QUasars in the Early uNiverse) on the 2.1m telescope at the McDonald observatory. The observation started at 2010 August 21, 05:12:48 UT, about 11.5 hrs after the BAT trigger.
In a stacked i-band image (3 x 300 sec), we identify a faint object within the error circle of the enhanced XRT position (Beardmore et al. GCN 12291).
The position of the i-band source is
```
  RA=22:52:49.49
  Dec=70:17:53.6
  with a positional error of ~0.5".
```
We are carrying our further observations to examine variability of the source.
GCN Circular #12296
Myungshin Im, Won-Kee Park (CEOU/Seoul National Univ), Soojong Pak, Giseon Baek, and Youngseok Oh (Kyunghee University)
The finding chart of the i-band image reported in Im et al. (GCN 12295) is available at
http://astro.snu.ac.kr/~mim/grb110820a.html
We also make a correction to the year of the observation reported in GCN 12295. It should be 2011, not 2010.
GCN Circular #12297
Myungshin Im, Won-Kee Park (CEOU/Seoul National Univ), Soojong Pak, Giseon Baek, and Youngseok Oh (Kyunghee University)
We revise the position of the afterglow candidate to be
```
   RA=22:52:46.49
   Dec=70:17:53.6
   with a positional error of ~0.5".
```
The 2nd set of i-band images were taken 3 hrs after the 1st set (Im et al. GCN 12295). Our analysis of the data shows no significant fading of the object (dm < 0.1 mag) during that time span.
GCN Circular #12298
S. Immler (NASA/CRESST/GSFC) and E. Troja (NASA/GSFC/ORAU) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 110820A 139 s after the BAT trigger (Troja et al., GCN Circ. 12288). No optical afterglow consistent with the enhanced XRT position (Beardmore et al., GCN Circ. 12291) and the position of the optical afterglow candidate Myungshin et al., GCN Circ. 12297) is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627) for the first finding chart (FC) exposure and subsequent exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

u_FC               139          389          246 >20.6
v                  445        24186         1395 >21.1
b                  394        12987          932 >22.0
u                  139        18761         2181 >21.8
w1                 494        18331         2155 >21.8
m2                 469        24536         1716 >20.6
w2                 420        23272         1396 >21.2
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.55 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #12300
E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, N.Tyurina, N.Shatskiy, P.Balanutsa, V.V.Chazov, P.V.Kortunov, A.Kuznetsov, D.Zimnukhov, M. Kornilov, A.Kuznetsov, D.Zimnukhov, M. Kornilov, A.Sankovich Sternberg Astronomical Institute, Moscow State University
O. Gres, K.Ivanov, V.A.Poleshchuk, S.Yazev, N.M.Budnev, O.Chuvalaev Irkutsk State University
A. Tlatov, A. Parhomenko, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory
V.Krushinski, I.Zalozhnich, T.Kopytova, A. Popov Ural State University, Kourovka
E. Sinyakov, V.Yurkov, Yu.Sergienko, D.Varda, I.Kudelina Blagoveschensk Educational State University, Blagoveschensk
MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Tunka(Siberia) was pointed to the GRB110820A 45 sec after notice time and 133 sec after GRB time at 2011-08-20 17:40:40.275 UT in two polarizations on one in each tube. During the analysis of the data of the first hour of observation following results have been received:
```
T-T(GRB)  T-T(GRB)  T-T(GRB)  Exptime    Limit    Filter  Coadd
start[s]  stop[s]   mean [s]    [s]    (5-sigma) 
---------------------------------------------------------------
133        163       148         30      16.4      P_      no
133        163       148         30      16.5      P|      no
133       2797      1465       2040      19.3      P_      14
133       2797      1465       2040      19.6      P|      14
133       2797      1465       4080      19.9     P|+P_    28
```
Image in filter P_+P| available here http://observ.pereplet.ru/images/evgeny/GRB110820A.jpg
The message may be cited.
GCN Circular #12306
V.V. Golovnya (Main Astro Obs, Kyiv) report: We have undertaken the review of the sky area in vicinity of GRB 110820A (Beardmore GCN Circ.12091) on astronegatives, collected in Ukrainian NAS Main astronomical observatory plate archive (1976-1996). All the plates with the possible object appearance are digitized using Microtek ScanMaker 9800XL TMA and Epson Expression 10000XL flatbed scanners and have been placed into Golosiiv Plate Archive database DBGPA with open access to them.
```
	The list of plates is given in the table:
YYYYMMDD TimeUT	--Plates--	Exp.	LimMag	Star USNOA2 
19830903.220221	GUA040C000207	16.0	15.75	1575-05316204
19841020.183916	GUA040C000521A	16.0	15.75	1575-05316204

Plates: the plate's identifier in GUA040C archive of DWA 
        (D/F=400/2000, M=103"/mm) of the Ukrainian NAS Main
        Astro obs in Kyiv (Marsden's number - 83)[1].
Exp.   - Duration of the maximum exposure (minutes). 
LimMag - Limited V mag, derived in the 15 minutes area around 
       the location given in Beardmore et al. GCN Circ.12091: 
       RA(J2000): 22h 52m 46.14s, Dec(J2000): +70d 17' 54.5"
Star USNOA2 - Comparison star.
```
The preview images of 2 areas together with the 15x15 min.of arc area from SkyMap can be found in http://gua.db.ukr-vo.org/img/grb/110820A/index.html The images with full resolution are available via e-mail on demand.
References: 1.L.Pakuliak DATABASE of GOLOSIIV PLATE ARCHIVE (DBGPA V2.0), http://gua.db.ukr-vo.org
GCN Circular #12321
Volnova (SAI MSU), E. Litvinenko (UBAI), I. Molotov (Institute of Applied Mathematics), A. Pozanenko (IKI)
We observed the field of the Swift GRB 110820A (Troja et al., GCN 12288) with 40-cm telescope ORI-40 of Kitab ISON observatory on Aug. 20 starting on 17:48:45 UT, i.e. 15.5 minutes after the BAT trigger. On the stacked image we do not detect any source within the enhanced XRT error box (Beardmore et al., GCN 12291). The photometry is based on the USNO B1.0 star USNO-B1.0 1603-0160240, (J2000) RA = 22:52:56.89 Dec = +70:18:37.5, assuming R 17.19:
```
 Tstart UT, T0+,        Filter, Exposure, OT, Upper Limit (3 sigma)
                 (mid, d)             (s)

 17:48:45   0.01072   R       5*120        n/d  19.2
 17:48:45   0.02734   R       28*120      n/d  19.6
```
GCN Circular #12707
A. Volnova (SAI MSU), M. Ibrahimov (UBAI), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:
We observed the field of the Swift GRB 110820A (Troja et al., GCN 12288) with AZT-22 telescope of Maidanak observatory on Aug. 20 starting on 21:54:54 UT in R band. We took 6 frames with exposure of 300 seconds under good weather condition and seeing (FWHM) of about 0.7". On the stacked image we do not detect the source reported by Im et al. (GCNs 12295, 12297). The photometry is based on the USNO B1.0 star USNO-B1.0 1603-0160240, (J2000) RA = 22:52:56.89 Dec = +70:18:37.5, assuming R =17.19:
```
 Tstart UT,  T0+,       Filter, Exposure, OT, Upper Limit (3 sigma)
                 (mid, d)            (s)

 21:54:54   0.18924  R        6*300        n/d  22.5
```

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Jochen Greiner, last update: 20-Dec-2011 [Disclaimer]