Gamma-ray Burst 120811C

(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 11 Aug 12 15:45:22 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     530689,   Seg_Num: 0
GRB_RA:          199.709d {+13h 18m 50s} (J2000),
                 199.826d {+13h 19m 18s} (current),
                 199.247d {+13h 16m 59s} (1950)
GRB_DEC:         +62.291d {+62d 17' 29"} (J2000),
                 +62.225d {+62d 13' 31"} (current),
                 +62.554d {+62d 33' 14"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       6297 [cnts]    Image_Peak=432 [image_cnts]
TRIGGER_DUR:     1.024 [sec] 
TRIGGER_INDEX:   137     E_range: 15-50 keV
BKG_INTEN:       36166 [cnts]
BKG_TIME:        56078.47 SOD {15:34:38.47} UT
BKG_DUR:         8 [sec]
GRB_DATE:        16150 TJD;   224 DOY;   12/08/11
GRB_TIME:        56092.17 SOD {15:34:52.17} UT
GRB_PHI:         159.57 [deg]
GRB_THETA:        21.24 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     22.89 [sigma]
IMAGE_SIGNIF:    12.60 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +1  +2  +0  +0 -46  +0 
SUN_POSTN:       141.78d {+09h 27m 08s}  +15.01d {+15d 00' 46"}
SUN_DIST:         62.13 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:       68.06d {+04h 32m 16s}  +21.26d {+21d 15' 25"}
MOON_DIST:        88.19 [deg]
MOON_ILLUM:      33 [%]
GAL_COORDS:      117.45, 54.54 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      154.55, 61.00 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Coordinates.  
COMMENTS:        This Notice was delayed by more than 60 sec past the end of the trigger integration interval;  
COMMENTS:        probably due to it occurring during a Malindi downlink session.  
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 = 13.15,2.13 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 11 Aug 12 15:46:02 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     530689,   Seg_Num: 0
GRB_RA:          199.6833d {+13h 18m 43.99s} (J2000),
                 199.7998d {+13h 19m 11.94s} (current),
                 199.2204d {+13h 16m 52.89s} (1950)
GRB_DEC:         +62.3027d {+62d 18' 09.7"} (J2000),
                 +62.2366d {+62d 14' 11.8"} (current),
                 +62.5652d {+62d 33' 54.7"} (1950)
GRB_ERROR:       5.0 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       2.97e-09 [erg/cm2/sec]
GRB_SIGNIF:      10.14 [sigma]
IMG_START_DATE:  16150 TJD;   224 DOY;   12/08/11
IMG_START_TIME:  56160.87 SOD {15:36:00.87} UT,   68.7 [sec] since BAT Trigger Time
TAM[0-3]:        327.66 237.23 261.58 243.09
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       141.78d {+09h 27m 08s}  +15.01d {+15d 00' 46"}
SUN_DIST:         62.13 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:       68.07d {+04h 32m 17s}  +21.26d {+21d 15' 26"}
MOON_DIST:        88.17 [deg]
MOON_ILLUM:      33 [%]
GAL_COORDS:      117.47, 54.54 [deg] galactic lon,lat of the burst
ECL_COORDS:      154.52, 61.00 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 1.00 arcmin from the BAT position.  
COMMENTS:        The object found at this position is either a very bright burst or a cosmic ray hit.  
COMMENTS:        Examine the XRT Image to differentiate (CRs are much more compact); see examples at:  
COMMENTS:        http://www.swift.psu.edu/xrt/XRT_Postage_Stamp_Image_Photo_Gallery.htm .

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 11 Aug 12 15:46:13 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     530689,   Seg_Num: 0
GRB_RA:          199.6833d {+13h 18m 43.9s} (J2000),
                 199.7998d {+13h 19m 11.9s} (current),
                 199.2204d {+13h 16m 52.8s} (1950)
GRB_DEC:         +62.3027d {+62d 18' 09.7"} (J2000),
                 +62.2366d {+62d 14' 11.8"} (current),
                 +62.5652d {+62d 33' 54.7"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       103 [cnts]
IMG_START_DATE:  16150 TJD;   224 DOY;   12/08/11
IMG_START_TIME:  56160.87 SOD {15:36:00.87} UT,   68.7 [sec] since BAT Trigger Time
CENTROID_X:      295.06,  raw= 295  [pixels]
CENTROID_Y:      274.20,  raw= 274  [pixels]
ROLL:            247.84 [deg]
GAIN:            2
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -56.10
GRB_POS_XRT_Z:   -20.34
IMAGE_URL:       sw00530689000msxps_rw.img
SUN_POSTN:       141.78d {+09h 27m 08s}  +15.01d {+15d 00' 45"}
SUN_DIST:         62.13 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:       68.07d {+04h 32m 17s}  +21.26d {+21d 15' 27"}
MOON_DIST:        88.17 [deg]
MOON_ILLUM:      33 [%]
GAL_COORDS:      117.47, 54.54 [deg] galactic lon,lat of the burst
ECL_COORDS:      154.52, 61.00 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.  
COMMENTS:        The object found at this position is either a very bright burst or a cosmic ray hit.  
COMMENTS:        Examine the XRT Image to differentiate (CRs are much more compact); see examples at:  
COMMENTS:        http://www.swift.psu.edu/xrt/XRT_Postage_Stamp_Image_Photo_Gallery.htm .

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 11 Aug 12 15:46:26 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     530689,   Seg_Num: 0
GRB_RA:          199.6833d {+13h 18m 43.9s} (J2000),
                 199.7998d {+13h 19m 11.9s} (current),
                 199.2204d {+13h 16m 52.8s} (1950)
GRB_DEC:         +62.3027d {+62d 18' 09.7"} (J2000),
                 +62.2366d {+62d 14' 11.8"} (current),
                 +62.5652d {+62d 33' 54.7"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       103 [cnts]
IMG_START_DATE:  16150 TJD;   224 DOY;   12/08/11
IMG_START_TIME:  56160.87 SOD {15:36:00.87} UT,   68.7 [sec] since BAT Trigger Time
CENTROID_X:      295.06,  raw= 295  [pixels]
CENTROID_Y:      274.20,  raw= 274  [pixels]
ROLL:            247.84 [deg]
GAIN:            2
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -56.10
GRB_POS_XRT_Z:   -20.34
IMAGE_URL:       sw00530689000msxps_rw.img
SUN_POSTN:       141.78d {+09h 27m 08s}  +15.01d {+15d 00' 45"}
SUN_DIST:         62.13 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:       68.07d {+04h 32m 18s}  +21.26d {+21d 15' 27"}
MOON_DIST:        88.17 [deg]
MOON_ILLUM:      33 [%]
GAL_COORDS:      117.47, 54.54 [deg] galactic lon,lat of the burst
ECL_COORDS:      154.52, 61.00 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.  
COMMENTS:        The object found at this position is either a very bright burst or a cosmic ray hit.  
COMMENTS:        Examine the XRT Image to differentiate (CRs are much more compact); see examples at:  
COMMENTS:        http://www.swift.psu.edu/xrt/XRT_Postage_Stamp_Image_Photo_Gallery.htm .

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 11 Aug 12 15:47:28 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     530689,   Seg_Num: 0
GRB_RA:          199.709d {+13h 18m 50s} (J2000),
                 199.826d {+13h 19m 18s} (current),
                 199.247d {+13h 16m 59s} (1950)
GRB_DEC:         +62.291d {+62d 17' 29"} (J2000),
                 +62.225d {+62d 13' 31"} (current),
                 +62.554d {+62d 33' 14"} (1950)
GRB_DATE:        16150 TJD;   224 DOY;   12/08/11
GRB_TIME:        56092.17 SOD {15:34:52.17} UT
TRIGGER_INDEX:   137
GRB_PHI:         159.57 [deg]
GRB_THETA:        21.24 [deg]
DELTA_TIME:      71.00 [sec]
TRIGGER_DUR:     1.024 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     22.89 [sigma]
IMAGE_SIGNIF:    12.60 [sigma]
LC_URL:          sw00530689000msb.lc
SUN_POSTN:       141.79d {+09h 27m 08s}  +15.01d {+15d 00' 44"}
SUN_DIST:         62.13 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:       68.08d {+04h 32m 20s}  +21.26d {+21d 15' 29"}
MOON_DIST:        88.19 [deg]
MOON_ILLUM:      33 [%]
GAL_COORDS:      117.45, 54.54 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      154.55, 61.00 [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 = 13.15,2.13 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 11 Aug 12 15:47:59 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     530689,   Seg_Num: 0
POINT_RA:        199.707d {+13h 18m 50s} (J2000)
POINT_DEC:       +62.290d {+62d 17' 25"} (J2000)
POINT_ROLL:      247.841d
IMG_START_DATE:  16150 TJD;   224 DOY;   12/08/11
IMG_START_TIME:  56168.06 SOD {15:36:08.06} UT,   75.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.159
N_STARS:         30
X_OFFSET:        456 [pixels]
Y_OFFSET:        552 [pixels]
X_MAX:           1415 [pixels]
Y_MAX:           1511 [pixels]
DET_THRESH:      12
PHOTO_THRESH:    6
SL_URL:          sw00530689000msufc0075.fits
SUN_POSTN:       141.79d {+09h 27m 09s}  +15.01d {+15d 00' 44"}
SUN_DIST:         62.13 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:       68.09d {+04h 32m 21s}  +21.26d {+21d 15' 30"}
MOON_DIST:        88.18 [deg]
MOON_ILLUM:      33 [%]
GAL_COORDS:      117.45, 54.55 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      154.55, 61.00 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 11 Aug 12 15:48:39 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     530689,   Seg_Num: 0
POINT_RA:        199.707d {+13h 18m 50s} (J2000)
POINT_DEC:       +62.290d {+62d 17' 25"} (J2000)
ROLL:            247.841d
IMG_START_DATE:  16150 TJD;   224 DOY;   12/08/11
IMG_START_TIME:  56168.06 SOD {15:36:08.06} UT,   75.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     366392177
X_OFFSET:        869 [pixels]
Y_OFFSET:        939 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1029
Y_GRB_POS:       1099
BINNING_INDEX:   1
IM_URL:          sw00530689000msuni0085.fits
SUN_POSTN:       141.79d {+09h 27m 09s}  +15.01d {+15d 00' 44"}
SUN_DIST:         62.13 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:       68.09d {+04h 32m 23s}  +21.26d {+21d 15' 31"}
MOON_DIST:        88.18 [deg]
MOON_ILLUM:      33 [%]
GAL_COORDS:      117.45, 54.55 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      154.55, 61.00 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 11 Aug 12 15:48:57 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     530689,   Seg_Num: 0
POINT_RA:        199.707d {+13h 18m 50s} (J2000)
POINT_DEC:       +62.290d {+62d 17' 25"} (J2000)
ROLL:            247.841d
IMG_START_DATE:  16150 TJD;   224 DOY;   12/08/11
IMG_START_TIME:  56168.06 SOD {15:36:08.06} UT,   75.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     366392177
X_OFFSET:        869 [pixels]
Y_OFFSET:        939 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1029
Y_GRB_POS:       1099
BINNING_INDEX:   1
IM_URL:          sw00530689000msuni0085.fits
SUN_POSTN:       141.79d {+09h 27m 09s}  +15.01d {+15d 00' 43"}
SUN_DIST:         62.13 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:       68.10d {+04h 32m 23s}  +21.26d {+21d 15' 32"}
MOON_DIST:        88.18 [deg]
MOON_ILLUM:      33 [%]
GAL_COORDS:      117.45, 54.55 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      154.55, 61.00 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 11 Aug 12 15:48:20 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     530689,   Seg_Num: 0
POINT_RA:        199.707d {+13h 18m 50s} (J2000)
POINT_DEC:       +62.290d {+62d 17' 25"} (J2000)
POINT_ROLL:      247.841d
IMG_START_DATE:  16150 TJD;   224 DOY;   12/08/11
IMG_START_TIME:  56168.06 SOD {15:36:08.06} UT,   75.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.159
N_STARS:         30
X_OFFSET:        456 [pixels]
Y_OFFSET:        552 [pixels]
X_MAX:           1415 [pixels]
Y_MAX:           1511 [pixels]
DET_THRESH:      12
PHOTO_THRESH:    6
SL_URL:          sw00530689000msufc0075.fits
SUN_POSTN:       141.79d {+09h 27m 09s}  +15.01d {+15d 00' 44"}
SUN_DIST:         62.13 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:       68.09d {+04h 32m 22s}  +21.26d {+21d 15' 31"}
MOON_DIST:        88.18 [deg]
MOON_ILLUM:      33 [%]
GAL_COORDS:      117.45, 54.55 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      154.55, 61.00 [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:     Sat 11 Aug 12 15:50:29 UT
NOTICE_TYPE:     Swift-UVOT Position
TRIGGER_NUM:     530689,   Seg_Num: 0
GRB_RA:          199.6825d {+13h 18m 43.80s} (J2000),
                 199.7990d {+13h 19m 11.75s} (current),
                 199.2196d {+13h 16m 52.69s} (1950)
GRB_DEC:         +62.3007d {+62d 18' 02.5"} (J2000),
                 +62.2346d {+62d 14' 04.6"} (current),
                 +62.5632d {+62d 33' 47.5"} (1950)
GRB_ERROR:       0.8 [arcsec radius, statistical only]
GRB_MAG:         18.39 +/- 0.14 [mag]
FILTER:          10, White
IMG_START_DATE:  16150 TJD;   224 DOY;   12/08/11
IMG_START_TIME:  56168.00 SOD {15:36:08.00} UT,   75.8 [sec] since BAT Trigger Time
SUN_POSTN:       141.79d {+09h 27m 09s}  +15.01d {+15d 00' 42"}
SUN_DIST:         62.12 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:       68.11d {+04h 32m 26s}  +21.26d {+21d 15' 35"}
MOON_DIST:        88.16 [deg]
MOON_ILLUM:      33 [%]
GAL_COORDS:      117.47, 54.54 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      154.52, 61.00 [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 UVOT position is 7.2 arcsec from the XRT position.  
COMMENTS:        Result based on Genie data.  
COMMENTS:        Notice generated automatically.

GCN Circular #13622
B. N. Barlow (PSU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), D. Grupe (PSU), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL) and B.-B. Zhang (PSU) report on behalf of the Swift Team:
At 15:34:52 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 120811C (trigger=530689). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 199.709, +62.291 which is
```
   RA(J2000)  =  13h 18m 50s
   Dec(J2000) = +62d 17' 29"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a single bright peak with a duration of about 35 sec. The peak count rate was ~7000 counts/sec (15-350 keV), at ~6 sec after the trigger.
The XRT began observing the field at 15:36:00.8 UT, 68.7 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 199.6833, 62.3027 which is equivalent to:
```
   RA(J2000)  = +13h 18m 43.99s
   Dec(J2000) = +62d 18' 09.7" 
```
with an uncertainty of 5.0 arcseconds (radius, 90% containment). This location is 60 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy.
The initial flux in the 2.5 s image was 2.97e-09 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 75 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at
```
  RA(J2000)  =  13:18:43.81 = 199.68253
  DEC(J2000) = +62:18:02.7  =  62.30076
```
with a 90%-confidence error radius of about 0.75 arc sec. This position is 7.1 arc sec. from the center of the XRT error circle. The estimated magnitude is 18.40 with a 1-sigma error of about 0.15. No correction has been made for the expected extinction corresponding to E(B-V) of 0.03.
Burst Advocate for this burst is B. N. Barlow (bnb2 AT psu.edu). 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 11 Aug 12 15:58:44 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     530689,   Seg_Num: 0
POINT_RA:        199.703d {+13h 18m 49s} (J2000)
POINT_DEC:       +62.293d {+62d 17' 34"} (J2000)
POINT_ROLL:      247.837d
IMG_START_DATE:  16150 TJD;   224 DOY;   12/08/11
IMG_START_TIME:  56962.16 SOD {15:49:22.16} UT,   870.0 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.666
N_STARS:         95
X_OFFSET:        309 [pixels]
Y_OFFSET:        379 [pixels]
X_MAX:           1748 [pixels]
Y_MAX:           1818 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw00530689000msufc0869.fits
SUN_POSTN:       141.79d {+09h 27m 10s}  +15.01d {+15d 00' 36"}
SUN_DIST:         62.13 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:       68.18d {+04h 32m 44s}  +21.26d {+21d 15' 50"}
MOON_DIST:        88.15 [deg]
MOON_ILLUM:      33 [%]
GAL_COORDS:      117.45, 54.54 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      154.55, 61.00 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 11 Aug 12 15:58:55 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     530689,   Seg_Num: 0
POINT_RA:        199.703d {+13h 18m 49s} (J2000)
POINT_DEC:       +62.293d {+62d 17' 34"} (J2000)
POINT_ROLL:      247.837d
IMG_START_DATE:  16150 TJD;   224 DOY;   12/08/11
IMG_START_TIME:  56962.16 SOD {15:49:22.16} UT,   870.0 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.666
N_STARS:         95
X_OFFSET:        309 [pixels]
Y_OFFSET:        379 [pixels]
X_MAX:           1748 [pixels]
Y_MAX:           1818 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw00530689000msufc0869.fits
SUN_POSTN:       141.79d {+09h 27m 10s}  +15.01d {+15d 00' 36"}
SUN_DIST:         62.13 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:       68.18d {+04h 32m 44s}  +21.26d {+21d 15' 50"}
MOON_DIST:        88.14 [deg]
MOON_ILLUM:      33 [%]
GAL_COORDS:      117.45, 54.54 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      154.55, 61.00 [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:     Sat 11 Aug 12 15:59:35 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     530689,   Seg_Num: 0
GRB_RA:          199.6829d {+13h 18m 43.89s} (J2000),
                 199.7994d {+13h 19m 11.84s} (current),
                 199.2200d {+13h 16m 52.79s} (1950)
GRB_DEC:         +62.3001d {+62d 18' 00.3"} (J2000),
                 +62.2340d {+62d 14' 02.4"} (current),
                 +62.5626d {+62d 33' 45.4"} (1950)
GRB_ERROR:       2.0 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  16150 TJD;   224 DOY;   12/08/11
IMG_START_TIME:  56313.00 SOD {15:38:33.00} UT,   220.8 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       141.79d {+09h 27m 10s}  +15.01d {+15d 00' 35"}
SUN_DIST:         62.12 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:       68.19d {+04h 32m 46s}  +21.26d {+21d 15' 52"}
MOON_DIST:        88.13 [deg]
MOON_ILLUM:      33 [%]
GAL_COORDS:      117.47, 54.54 [deg] galactic lon,lat of the burst
ECL_COORDS:      154.52, 61.00 [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 11 Aug 12 15:59:55 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     530689,   Seg_Num: 0
POINT_RA:        199.703d {+13h 18m 49s} (J2000)
POINT_DEC:       +62.293d {+62d 17' 34"} (J2000)
ROLL:            247.837d
IMG_START_DATE:  16150 TJD;   224 DOY;   12/08/11
IMG_START_TIME:  56962.16 SOD {15:49:22.16} UT,   870.0 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     366392971
X_OFFSET:        868 [pixels]
Y_OFFSET:        938 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1028
Y_GRB_POS:       1098
BINNING_INDEX:   1
IM_URL:          sw00530689000msuni0879.fits
SUN_POSTN:       141.79d {+09h 27m 10s}  +15.01d {+15d 00' 35"}
SUN_DIST:         62.13 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:       68.19d {+04h 32m 46s}  +21.26d {+21d 15' 52"}
MOON_DIST:        88.14 [deg]
MOON_ILLUM:      33 [%]
GAL_COORDS:      117.45, 54.54 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      154.55, 61.00 [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 11 Aug 12 16:00:20 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     530689,   Seg_Num: 0
POINT_RA:        199.703d {+13h 18m 49s} (J2000)
POINT_DEC:       +62.293d {+62d 17' 34"} (J2000)
ROLL:            247.837d
IMG_START_DATE:  16150 TJD;   224 DOY;   12/08/11
IMG_START_TIME:  56962.16 SOD {15:49:22.16} UT,   870.0 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     366392971
X_OFFSET:        868 [pixels]
Y_OFFSET:        938 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1028
Y_GRB_POS:       1098
BINNING_INDEX:   1
IM_URL:          sw00530689000msuni0879.fits
SUN_POSTN:       141.79d {+09h 27m 11s}  +15.01d {+15d 00' 35"}
SUN_DIST:         62.13 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:       68.20d {+04h 32m 47s}  +21.26d {+21d 15' 53"}
MOON_DIST:        88.14 [deg]
MOON_ILLUM:      33 [%]
GAL_COORDS:      117.45, 54.54 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      154.55, 61.00 [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 #13623
D. Denisenko, E. Gorbovskoy, V. Lipunov, V. Kornilov, D. Kuvshinov, A. Belinski, N. Tyurina, N. Shatskiy, P. Balanutsa, D. Zimnukhov, A. Kuznetsov, V.V. Chazov, A. Sankovich Lomonosov Moscow State University, Sternberg Astronomical Institute
V. Yurkov, Yu. Sergienko, D. Varda, E. Sinyakov Blagoveschensk Educational State University, Blagoveschensk
A. Tlatov, A.V. Parhomenko, D. Dormidontov, V. Sennik Kislovodsk Solar Station of the Pulkovo Observatory
V. Krushinski, I. Zalozhnich, A. Popov, A. Bourdanov, A. Punanova Ural Federal University
H. Levato, C. Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)
C. Mallamaci, C. Lopez, F. Podest Observatorio Astronomico Felix Aguilar (OAFA) report:
MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Blagoveschensk was pointed to GRB 120811C (Barlow et al., GCN 13622) 665 sec after GRB time, at 2012-08-11 15:45:57 UT. Observations were performed simultaneously in two tubes with mutually perpendicular polarizations. First two pairs of images were obtained with 130 and 160 sec exposures, followed by the set of 180-sec exposures. On our images we find the fading optical transient at the coordinates:
```
  R.A. (J2000) = 13 18 44.01
  Dec. (J2000) = +62 18 02.7
```
which are consistent with the position of UVOT candidate afterglow reported in GCN 13622.
Photometry of GRB 120811C afterglow was performed using SDSS J131828.08+621651.3 (r=14.74) as the reference star. To improve the signal-to-noise ratio, images were combined by four. The resulting magnitudes of the afterglow in the Western tube with a better image quality (FWHM=2.6-3.2") are listed in the Table below.
```
----------------------------------------------
T_mid UT | T-T0, s | Exptime |  Mag. | Mag.err
---------+---------+---------+-------+--------
15:51:48 | 1016    |  650    |  18.4 |  0.10
16:04:46 | 1794    |  720    |  18.9 |  0.17
16:18:37 | 2625    |  720    |  19.3 |  0.27
16:32:27 | 3455    |  720    |  19.0 |  0.24
16:46:16 | 4284    |  720    | <19.5 |  N/A
17:00:04 | 5112    |  720    | <19.5 |  N/A
----------------------------------------------
```
The detailed analysis of the complete data set is continuing.
This message can be cited.
GCN Circular #13624
Klotz A. (IRAP-CNRS-OMP), Gendre B. (ASDC/INAF-OAR), Boer M. (UNS-CNRS-OCA), Atteia J.L. (IRAP-CNRS-OMP) report:
We imaged the field of GRB 120811C detected by SWIFT (trigger 530689) with the TAROT robotic telescope (D=25cm) located at the Calern observatory, France.
The observations started 3.98h after the GRB trigger. The elevation of the field decreased from 50 degrees above horizon and weather conditions were good.
We co-added a series of exposures but we do not find any optical transcient at the afterglow position (Barlow et al. GCNC 13622, Denisenko et al. GCNC 13623):
```
-------------------------------
T-T0 start | T-T0 End |  Mag. |
-----------+----------+-------+
    246 min |  313 min | >19.5 |
-------------------------------
```
Magnitudes were estimated with the nearby USNO-B1 stars and are not corrected for galactic dust extinction.
This message may be cited.
GCN Circular #13625
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team.
Using 1291 s of XRT Photon Counting mode data and 2 UVOT images for GRB 120811C, 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 = 199.68285, +62.30068 which is equivalent to:
```
RA (J2000): 13h 18m 43.88s
Dec (J2000): +62d 18' 02.4"
```
with an uncertainty of 1.7 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177).
This circular was automatically generated, and is an official product of the Swift-XRT team.
GCN Circular #13626
A. Galeev (Kazan Federal University), I. Khamitov (TUG), I. Bikmaev, N. Sakhibullin (Kazan Federal University), R. Burenin, M. Pavlinsky, R. Sunyaev (IKI), Z. Eker (TUG), U. Kiziloglu (METU), E. Gogus (Sabanci Uni.)
report:
We observed the field of the Swift-BAT GRB 120811C (Barlow et al. GCN 13622) with Russian-Turkish 1.5-m telescope (RTT150, Bakirlitepe, TUBITAK National Observatory, Turkey), starting at 11 Aug, 18:52 UT, i.e. approximately 3.3 hours after the burst, using TFOSC instrument. We made a serie of 300-600s images in R and V.
The afterglow is detected at the position:
RA=13:18:43.83, DEC=62:18:02.6 (J2000)
with positional error about 0.1 arcsec, which is consistent with that measured by UVOT and MASTER (Denisenko et al., GCN 13623).
We measured the afterglow magnitude as m_R=20.00+-0.05 (calibrated relative to USNO-B1 stars). Observations are continuing.
GCN Circular #13628
C. C. Thoene (IAA-CSIC), A. de Ugarte Postigo (IAA-CSIC, DARK), J. Gorosabel, R. Sanchez-Ramirez (IAA-CSIC) and J. P. U. Fynbo (DARK) G. Gomez Velarde (GTC) report on behalf of a larger collaboration:
We observed the afterglow of GRB 120811C (Barlow et al., GCN 13622) with OSIRIS at the 10.4m GTC telescope starting at UT 22:07 (6.5 hr after the burst) for a total exposure time of 2400s. We used grism 1000B covering the wavelength range between 3700 and 7800 Angstrom.
Despite Calima, the continuum is clearly detected and the spectrum shows strong Ly alpha and Ly beta absorption as well as a number of absorption lines (SII, SiII, OI, CII, CIV, SiIV, AlII, AlIII, NiII, ZnII and SiII*) at a common redshift of z=2.671.
GCN Circular #13629
P. Kuin, S. R. Oates (MSSL-UCL) and B.N. Barlow (PSU) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 120811C 76 s after the BAT trigger (Barlow et al., GCN Circ. 13622). A source consistent with the XRT position Evans et al., GCN Circ. 13625 is detected in the initial UVOT exposures.
The preliminary UVOT position is:
```
    RA  (J2000) =  13:18:43.82 = 199.68258 (deg.)
    Dec (J2000) = +62:18:02.8  =  62.30077 (deg.)
```
with an estimated uncertainty of 0.52 arc sec. (radius, 90% confidence).
Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white               76          226          147         18.59 +/- 0.05
v                  620         1243           78         18.49 +/- 0.19
b                  544          739           39         18.95 +/- 0.19
u                  288          538          246         18.61 +/- 0.09
w1                 670         1464           97        >20.0
m2                 819         1439           78        >20.5
w2                 595         1219           78        >19.7
```
The absence of a detection in the uv bands is consistent with the reported redshift from Thoene et al., GCN Circ. 13628.
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.03 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #13630
P.A. Evans (U. Leicester), O.M. Littlejohns (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. Maselli (INAF-IASFPA), M.C. Stroh (PSU), D.N. Burrows (PSU), J.A. Kennea (PSU), J.P. Osborne (U. Leicester) and B.N. Barlow report on behalf of the Swift-XRT team:
We have analysed 6.5 ks of XRT data for GRB 120811C (Barlow et al. GCN Circ. 13622), from 56 s to 40.2 ks after the BAT trigger. The data comprise 137 s in Windowed Timing (WT) mode (the first 8 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN. Circ 13625).
The light curve can be modelled with a series of power-law decays. The initial decay index is alpha=3.12 (+0.13, -0.14). At T+224 s the decay flattens to an alpha of 0.44 (+0.12, -0.27) before breaking again at T+1468 s to a final decay with index alpha=1.06 (+0.19, -0.09).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.74 (+0.14, -0.13). The best-fitting absorption column is 1.08 (+0.22, -0.20) x 10^21 cm^-2, in excess of the Galactic value of 2.1 x 10^20 cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a photon index of 2.00 (+/-0.15) and a best-fitting absorption column of 8.8 (+3.4, -3.1) x 10^20 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.6 x 10^-11 (4.5 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     8.8 (+3.4, -3.1) x 10^20 cm^-2
Galactic foreground: 2.1 x 10^20 cm^-2
Excess significance: 3.6 sigma
Photon index:	     2.00 (+/-0.15)
```
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00530689.
This circular is an official product of the Swift-XRT team.
GCN Circular #13631
U.Quadri, L.Strabla and R.Girelli, A.Quadri report:
We imaged the field of GRB 120811C detected by SWIFT(trigger 530689) with the robotic telescope of (IAU station 565) Bassano Bresciano Observatory, Italy.
The observations started 266min. after the GRB trigger,with our schmidt telescope D=320 mm F/D=3.1.
Weather conditions were good.
We co-added a series of 30 exposures.
We did not found any optical counterpart in the error box of the XRTcandidate (Barlow et al. GCNC 13622).
```
Start      End       Vlim
266min     326min    19.2
```
Magnitudes were estimated with the UCAC-3
The message may be cited.
GCN Circular #13632
J. P. U. Fynbo (DARK/NBI), D. Xu (WIS), P. Jakobsson (U. Iceland), D. Armstrong (U. Warwick), R. Cardenes (NOT) report on behalf of a larger collaboration:
We observed the optical afterglow of GRB 120811C (Barlow et al., GCN 13622) using the 2.5m Nordic Optical Telescope (NOT) equipped with ALFOSC. Spectroscopic observations started at 21:58 UT on 2012-08-11 (i.e., 6.4 hr after the BAT trigger) with exposure time of 3x1800s, covering the wavelength range of ~3800A to ~8000A. The afterglow was detected in each of the 1800s frames though the weather was dusty to a certain degree.
The spectrum exhibits a clear Damped Lyman Alpha (DLA) absorption feature at about 4460A. Redward of Lyman alpha the spectrum shows quite a few significant absorption lines, including Si II, O I, C II, C IV, Si IV, all at a common redshift of z=2.67, in good agreement with the measurement in Thoene at al. (GCN 13628).
GCN Circular #13634
H. A. Krimm (GSFC/USRA), B. N. Barlow (PSU), S. D. Barthelmy (GSFC), T. Sakamoto (GSFC/UMBC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 120811C (trigger #530689) (Barlow, et al., GCN Circ. 13622). The BAT ground-calculated position is RA, Dec = 199.690, 62.297 deg, which is
```
   RA(J2000)  =  13h 18m 45.5s 
   Dec(J2000) = +62d 17' 50.3" 
```
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 89%.
The mask-weighted light curve shows a nearly symmetric peak starting at ~T-10 sec, peaking at ~T+6 sec, and ending at ~T+40 sec. T90 (15-350 keV) is 26.8 +- 3.7 sec (estimated error including systematics).
The time-averaged spectrum from T-9.7 to T+42.9 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 1.40 +- 0.30, and Epeak of 42.9 +- 5.7 keV (chi squared 59.5 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 3.0 +- 0.3 x 10^-6 erg/cm2 and the 1-sec peak flux measured from T+5.27 sec in the 15-150 keV band is 4.1 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index of 2.04 +- 0.06 (chi squared 74.5 for 57 d.o.f.). 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/530689/BA/
GCN Circular #13635
K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk Irkutsk State University
E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, N.Tyurina, N.Shatskiy, P.Balanutsa, D.Zimnukhov, A.Kuznetsov, V.V.Chazov, A.Kuznetsov, A.Sankovich Sternberg Astronomical Institute, Moscow State University
V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov Blagoveschensk Educational State University, Blagoveschensk
A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory
V.Krushinski, I.Zalozhnih, A. Popov Ural Federal University, Kourovka
Hugo Levato and Carlos Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)
Claudio Mallamaci, Carlos Lopez and Federico Podest Observatorio Astronomico Felix Aguilar (OAFA)
MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Tunka was pointed to the GRB120811C (Barlow et al., GCN 13622) 40 sec s after notice time and 676 sec after GRB time at 2012-08-11 15:46:08.449 UT. On our first (130s exposure) set we have found OT within SWIFT-BAT error-box in two polarizations.
The preliminary robotic photometry (m=0.2B + 0.8R, Usno B magnitudes) is:
```
datetime	                   coord2000           Band     mag   error

2012-08-11 15:46:08.449	13h 18m 43.90s , +62d 18m 02s.1	P|	17.3	0.2
2012-08-11 15:46:09.684	13h 18m 43.86s , +62d 18m 02s.3	P-	17.2	0.1
2012-08-11 15:49:12.268	13h 18m 43.76s , +62d 18m 02s.3	P|	17.6	0.2
2012-08-11 15:49:12.282	13h 18m 43.93s , +62d 18m 02s.6	P-	17.6	0.2
2012-08-11 15:52:52.452	13h 18m 43.75s , +62d 18m 01s.8	P|	17.8	0.2
```
So, MASTER-Net have simultaneous optical observations in four polarizations (see Denisenko et al., GCN 13623) of GRB120811C.
The message may be cited.
GCN Circular #13636
A. Galeev (Kazan Federal University), I. Khamitov (TUG), I. Bikmaev, N. Sakhibullin (Kazan Federal University), R. Burenin, M. Pavlinsky, R. Sunyaev (IKI), Z. Eker (TUG), U. Kiziloglu (METU), E. Gogus (Sabanci Uni.)
report:
We continued the observations of the field of the Swift-BAT GRB 120811C (Barlow et al. GCN 13622, Galeev et al., GCN 13626) with Russian-Turkish 1.5-m telescope (RTT150, Bakirlitepe, TUBITAK National Observatory, Turkey). The second epoch observations were started at 12 Aug, 18:38 UT, i.e. approximately 27.05 hours after the burst. We made a serie of 300s images in R using TFOSC instrument.
The afterglow was clearly detected in the combined image. Using USNO-B1 stars as reference, we estimated the afterglow magnitude as m_R=22.3+-0.2.
Fitting this point together with the data from RTT150 first epoch observations (Galeev et al., GCN 13626), gives the power law decay with index alpha = 1.04 +- 0.05, consistent with late time decay in X-rays, as it was observed with XRT (Evans et al., GCN 13630).
When all RTT150 data are compared with the data of MASTER telescopes (Denisenko et al., GCN 13623, Ivanov et al., 13635), the power law break at few hours time scale is found, approximately consistent with the position of second break observed in X-rays with XRT (Evans et al., GCN 13630). However, better cross-calibration between RTT and MASTER photometry should be done for more reliable light curve modelling.
The light curve and direct images of the field can be found at:
http://hea.iki.rssi.ru/grb/120811c/indexeng.html
GCN Circular #13637
T. Laskar, A. Zauderer and E. Berger (Harvard) report:
"We observed the position of GRB 120811C (Barlow et al. GCN 13622) with the EVLA at 2012 Aug 11.79 UT (1.14 days after the burst). No significant radio emission is detected at the enhanced Swift-XRT position (Evans et al. GCN 13625), the UVOT position (Kuin et al. GCN 13629) or optical position (Denisenko et al. GCN 13623; Galeev et al. GCN 13626; Ivanov et al. GCN 13635), to a three-sigma upper limit of 76 uJy at 6.0 GHz."
GCN Circular #13642
Peter Jenke (MSFC/NPP) reports on behalf of the Fermi GBM Team:
"At 15:34:55.09 UT on 11 August 2012, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 120811C (trigger 366392098 / 120811649) which was also detected by the Swift/BAT (Barthelmy et al. 2012, GCN 13622). The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight is 133 degrees.
The GBM light curve consists of a single pulse with a duration (T90) of about 14.3 s (50-300 keV). The time-averaged spectrum from T0-6.14 s to T0+10.24 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.71 +/- 0.20 and the cutoff energy, parameterized as Epeak, is 54 +/- 3 keV.
The event fluence (10-1000 keV) in this time interval is (2.98 +/- 0.08)E-06 ergs/cm^2. The 1-sec peak photon flux measured starting from T0+3.072 s in the 10-1000 keV band is 5.9304 +/- 0.55 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN Report 378.1
GCN_Report 378.1 has been posted: http://gcn.gsfc.nasa.gov/reports/report_378_1.pdf by B.N. Barlow at PSU titled: "Swift Observations of GRB 120811C"
GCN Circular #13679
L. Elenin (KIAM), A. Volnova (SAI MSU), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:
We observed the field of GRB 120811C (Barlow et al., GCN 13622) with 0.45-m telescope of ISON-NM observatory starting on Aug. 12 (UT) 03:25:07. We took several unfiltered images of 30 s exposures. The optical afterglow (Denisenko et al., GCN 13623) is marginally detected in co-added frames at coordinates (J2000) 13:18:43.98 +62:18:03.4 with uncertainty of 0.5 arcsec in both coordinates. A preliminary photometry of co-added frames is based on the USNO-B1.0 (R2) nearby stars is following:
```
T_start,     T0+,           Exposure,  OT,              UL (3 sigma)
(UT)           mid, d         (s)

03:25:07   0.5095      1800           21.5 +/-0.5   21.2
```
GCN Circular #13693
E. Litvinenko (UBAI), A. Volnova (SAI MSU), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:
We observed the field of GRB 120811C (Barlow et al., GCN 13622) with 0.4-m telescope of ISON-Kitab observatory starting on Aug. 11 (UT) 15:53:49. We took several unfiltered images of 30 s exposures. The optical afterglow (Denisenko et al., GCN 13623) is clearly detected in single initial frames. A photometry of some co-added frames is based on the SDSS stars
```
SDSS id               RA                 Dec       R
J131912.45+621444.3 13 19 12,453  +62 14 44,35   16.63
J131815,89+621830,6 13 18 15,896  +62 18 30,67   16.64
```
is following:
```
T_start,     T0+,           Exposure,  OT,
(UT)           mid, d         (s)

15:53:49    0.01392    4x30          17,90 +/-0.13
15:56:05    0.01569    5x30          17.95 +/-0.13
15:58:55    0.01841  10x30          18.20 +/-0.10
16:04:35    0.02356  15x30          18.45 +/-0.11
16:13:06    0.03145  25x30          18.40 +/-0.07
```

Back to JG's homepage

Jochen Greiner, last update: 20-Aug-2012 [Disclaimer]