Gamma-ray Burst 131205A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

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Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 05 Dec 13 09:19:16 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     580267,   Seg_Num: 0
GRB_RA:          131.609d {+08h 46m 26s} (J2000),
                 131.686d {+08h 46m 45s} (current),
                 131.331d {+08h 45m 19s} (1950)
GRB_DEC:         -60.174d {-60d 10' 25"} (J2000),
                 -60.226d {-60d 13' 31"} (current),
                 -59.990d {-59d 59' 22"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       6710 [cnts]    Image_Peak=254 [image_cnts]
TRIGGER_DUR:     2.048 [sec] 
TRIGGER_INDEX:   262     E_range: 25-100 keV
BKG_INTEN:       67356 [cnts]
BKG_TIME:        33484.64 SOD {09:18:04.64} UT
BKG_DUR:         24 [sec]
GRB_DATE:        16631 TJD;   339 DOY;   13/12/05
GRB_TIME:        33518.94 SOD {09:18:38.94} UT
GRB_PHI:         -33.28 [deg]
GRB_THETA:        19.72 [deg]
SOLN_STATUS:     0x403
RATE_SIGNIF:     11.13 [sigma]
IMAGE_SIGNIF:    8.19 [sigma]
MERIT_PARAMS:     +1  +0  +0  +1  +2  -1  +0  +0  -9  +0 
SUN_POSTN:       252.00d {+16h 48m 00s}  -22.41d {-22d 24' 19"}
SUN_DIST:         84.31 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:      287.14d {+19h 08m 34s}  -17.71d {-17d 42' 19"}
MOON_DIST:        99.58 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      276.60,-10.53 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      180.68,-70.71 [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 = 241.13,-8.90 [deg].  
COMMENTS:           
COMMENTS:        This trigger occured while the StarTracker had lost lock, so it is possibly bogus.

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 05 Dec 13 09:20:14 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     580267,   Seg_Num: 0
POINT_RA:        131.597d {+08h 46m 23s} (J2000)
POINT_DEC:       -60.169d {-60d 10' 07"} (J2000)
IMG_START_DATE:  16631 TJD;   339 DOY;   13/12/05
IMG_START_TIME:  33607.56 SOD {09:20:07.56} UT,   88.6 [sec] since BAT Trigger Time
COUNTS:          3    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        1    Max_iter_allowed= 4
ERROR_CODE:      1
COMMENTS:        SWIFT-XRT Nack Position.  
COMMENTS:        No source found in the image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 05 Dec 13 09:22:31 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     580267,   Seg_Num: 0
GRB_RA:          131.609d {+08h 46m 26s} (J2000),
                 131.686d {+08h 46m 45s} (current),
                 131.331d {+08h 45m 19s} (1950)
GRB_DEC:         -60.174d {-60d 10' 25"} (J2000),
                 -60.226d {-60d 13' 31"} (current),
                 -59.990d {-59d 59' 22"} (1950)
GRB_DATE:        16631 TJD;   339 DOY;   13/12/05
GRB_TIME:        33518.94 SOD {09:18:38.94} UT
TRIGGER_INDEX:   262
GRB_PHI:         -33.28 [deg]
GRB_THETA:        19.72 [deg]
DELTA_TIME:      -70.00 [sec]
TRIGGER_DUR:     2.048 [sec] 
SOLN_STATUS:     0x403
RATE_SIGNIF:     11.13 [sigma]
IMAGE_SIGNIF:    8.19 [sigma]
LC_URL:          sw00580267000msb.lc
SUN_POSTN:       252.00d {+16h 48m 00s}  -22.41d {-22d 24' 20"}
SUN_DIST:         84.31 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:      287.18d {+19h 08m 43s}  -17.70d {-17d 42' 01"}
MOON_DIST:        99.59 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      276.60,-10.53 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      180.68,-70.71 [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 = 241.13,-8.90 [deg].  
COMMENTS:           
COMMENTS:        This trigger occured while the StarTracker had lost lock, so it is possibly bogus.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 05 Dec 13 09:24:42 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     580267,   Seg_Num: 0
POINT_RA:        131.596d {+08h 46m 23s} (J2000)
POINT_DEC:       -60.169d {-60d 10' 06"} (J2000)
ROLL:            126.760d
IMG_START_DATE:  16631 TJD;   339 DOY;   13/12/05
IMG_START_TIME:  33612.50 SOD {09:20:12.50} UT,   93.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     407928023
X_OFFSET:        859 [pixels]
Y_OFFSET:        859 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1019
Y_GRB_POS:       1019
BINNING_INDEX:   1
IM_URL:          sw00580267000msuni0105.fits
SUN_POSTN:       252.00d {+16h 48m 01s}  -22.41d {-22d 24' 21"}
SUN_DIST:         84.32 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:      287.20d {+19h 08m 49s}  -17.70d {-17d 41' 49"}
MOON_DIST:        99.60 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      276.60,-10.53 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      180.65,-70.72 [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:     Thu 05 Dec 13 09:25:06 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     580267,   Seg_Num: 0
POINT_RA:        131.596d {+08h 46m 23s} (J2000)
POINT_DEC:       -60.169d {-60d 10' 06"} (J2000)
ROLL:            126.760d
IMG_START_DATE:  16631 TJD;   339 DOY;   13/12/05
IMG_START_TIME:  33612.50 SOD {09:20:12.50} UT,   93.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     407928023
X_OFFSET:        859 [pixels]
Y_OFFSET:        859 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1019
Y_GRB_POS:       1019
BINNING_INDEX:   1
IM_URL:          sw00580267000msuni0105.fits
SUN_POSTN:       252.00d {+16h 48m 01s}  -22.41d {-22d 24' 21"}
SUN_DIST:         84.32 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:      287.21d {+19h 08m 50s}  -17.70d {-17d 41' 47"}
MOON_DIST:        99.60 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      276.60,-10.53 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      180.65,-70.72 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 05 Dec 13 09:30:55 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     580267,   Seg_Num: 0
POINT_RA:        131.623d {+08h 46m 29s} (J2000)
POINT_DEC:       -60.166d {-60d 09' 55"} (J2000)
POINT_ROLL:      126.734d
IMG_START_DATE:  16631 TJD;   339 DOY;   13/12/05
IMG_START_TIME:  33824.84 SOD {09:23:44.84} UT,   305.9 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.798
N_STARS:         190
X_OFFSET:        300 [pixels]
Y_OFFSET:        300 [pixels]
X_MAX:           1739 [pixels]
Y_MAX:           1739 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    3
SL_URL:          sw00580267000msufc0305.fits
SUN_POSTN:       252.01d {+16h 48m 02s}  -22.41d {-22d 24' 23"}
SUN_DIST:         84.31 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:      287.27d {+19h 09m 05s}  -17.69d {-17d 41' 14"}
MOON_DIST:        99.62 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      276.60,-10.52 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      180.67,-70.70 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 05 Dec 13 09:31:30 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     580267,   Seg_Num: 0
POINT_RA:        131.623d {+08h 46m 29s} (J2000)
POINT_DEC:       -60.166d {-60d 09' 55"} (J2000)
POINT_ROLL:      126.734d
IMG_START_DATE:  16631 TJD;   339 DOY;   13/12/05
IMG_START_TIME:  33824.84 SOD {09:23:44.84} UT,   305.9 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.798
N_STARS:         190
X_OFFSET:        300 [pixels]
Y_OFFSET:        300 [pixels]
X_MAX:           1739 [pixels]
Y_MAX:           1739 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    3
SL_URL:          sw00580267000msufc0305.fits
SUN_POSTN:       252.01d {+16h 48m 02s}  -22.41d {-22d 24' 23"}
SUN_DIST:         84.31 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:      287.28d {+19h 09m 06s}  -17.69d {-17d 41' 10"}
MOON_DIST:        99.63 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      276.60,-10.52 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      180.67,-70.70 [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:     Thu 05 Dec 13 09:32:21 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     580267,   Seg_Num: 0
POINT_RA:        131.623d {+08h 46m 29s} (J2000)
POINT_DEC:       -60.166d {-60d 09' 55"} (J2000)
ROLL:            126.734d
IMG_START_DATE:  16631 TJD;   339 DOY;   13/12/05
IMG_START_TIME:  33824.84 SOD {09:23:44.84} UT,   305.9 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     407928236
X_OFFSET:        859 [pixels]
Y_OFFSET:        859 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1019
Y_GRB_POS:       1019
BINNING_INDEX:   1
IM_URL:          sw00580267000msuni0317.fits
SUN_POSTN:       252.01d {+16h 48m 02s}  -22.41d {-22d 24' 23"}
SUN_DIST:         84.31 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:      287.28d {+19h 09m 08s}  -17.69d {-17d 41' 06"}
MOON_DIST:        99.63 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      276.60,-10.52 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      180.67,-70.70 [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:     Thu 05 Dec 13 09:32:40 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     580267,   Seg_Num: 0
POINT_RA:        131.623d {+08h 46m 29s} (J2000)
POINT_DEC:       -60.166d {-60d 09' 55"} (J2000)
ROLL:            126.734d
IMG_START_DATE:  16631 TJD;   339 DOY;   13/12/05
IMG_START_TIME:  33824.84 SOD {09:23:44.84} UT,   305.9 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     407928236
X_OFFSET:        859 [pixels]
Y_OFFSET:        859 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1019
Y_GRB_POS:       1019
BINNING_INDEX:   1
IM_URL:          sw00580267000msuni0317.fits
SUN_POSTN:       252.01d {+16h 48m 02s}  -22.41d {-22d 24' 23"}
SUN_DIST:         84.31 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:      287.29d {+19h 09m 09s}  -17.68d {-17d 41' 04"}
MOON_DIST:        99.63 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      276.60,-10.52 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      180.67,-70.70 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 05 Dec 13 09:36:19 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     580267,   Seg_Num: 0
POINT_RA:        131.623d {+08h 46m 29s} (J2000)
POINT_DEC:       -60.166d {-60d 09' 55"} (J2000)
POINT_ROLL:      126.734d
IMG_START_DATE:  16631 TJD;   339 DOY;   13/12/05
IMG_START_TIME:  34378.97 SOD {09:32:58.97} UT,   860.0 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.713
N_STARS:         190
X_OFFSET:        300 [pixels]
Y_OFFSET:        300 [pixels]
X_MAX:           1739 [pixels]
Y_MAX:           1739 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    7
SL_URL:          sw00580267000msufc0860.fits
SUN_POSTN:       252.01d {+16h 48m 03s}  -22.41d {-22d 24' 24"}
SUN_DIST:         84.31 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:      287.33d {+19h 09m 18s}  -17.68d {-17d 40' 43"}
MOON_DIST:        99.64 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      276.60,-10.52 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      180.67,-70.70 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 05 Dec 13 09:36:49 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     580267,   Seg_Num: 0
POINT_RA:        131.623d {+08h 46m 29s} (J2000)
POINT_DEC:       -60.166d {-60d 09' 55"} (J2000)
POINT_ROLL:      126.734d
IMG_START_DATE:  16631 TJD;   339 DOY;   13/12/05
IMG_START_TIME:  34378.97 SOD {09:32:58.97} UT,   860.0 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.713
N_STARS:         190
X_OFFSET:        300 [pixels]
Y_OFFSET:        300 [pixels]
X_MAX:           1739 [pixels]
Y_MAX:           1739 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    7
SL_URL:          sw00580267000msufc0860.fits
SUN_POSTN:       252.01d {+16h 48m 03s}  -22.41d {-22d 24' 24"}
SUN_DIST:         84.31 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:      287.33d {+19h 09m 20s}  -17.68d {-17d 40' 40"}
MOON_DIST:        99.64 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      276.60,-10.52 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      180.67,-70.70 [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:     Thu 05 Dec 13 09:37:57 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     580267,   Seg_Num: 0
POINT_RA:        131.623d {+08h 46m 29s} (J2000)
POINT_DEC:       -60.166d {-60d 09' 55"} (J2000)
ROLL:            126.734d
IMG_START_DATE:  16631 TJD;   339 DOY;   13/12/05
IMG_START_TIME:  34378.97 SOD {09:32:58.97} UT,   860.0 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     407928790
X_OFFSET:        859 [pixels]
Y_OFFSET:        859 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1019
Y_GRB_POS:       1019
BINNING_INDEX:   1
IM_URL:          sw00580267000msuni0872.fits
SUN_POSTN:       252.01d {+16h 48m 03s}  -22.41d {-22d 24' 25"}
SUN_DIST:         84.32 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:      287.34d {+19h 09m 23s}  -17.68d {-17d 40' 34"}
MOON_DIST:        99.65 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      276.60,-10.52 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      180.67,-70.70 [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:     Thu 05 Dec 13 09:38:17 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     580267,   Seg_Num: 0
POINT_RA:        131.623d {+08h 46m 29s} (J2000)
POINT_DEC:       -60.166d {-60d 09' 55"} (J2000)
ROLL:            126.734d
IMG_START_DATE:  16631 TJD;   339 DOY;   13/12/05
IMG_START_TIME:  34378.97 SOD {09:32:58.97} UT,   860.0 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     407928790
X_OFFSET:        859 [pixels]
Y_OFFSET:        859 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1019
Y_GRB_POS:       1019
BINNING_INDEX:   1
IM_URL:          sw00580267000msuni0872.fits
SUN_POSTN:       252.01d {+16h 48m 03s}  -22.41d {-22d 24' 25"}
SUN_DIST:         84.32 [deg]   Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN:      287.35d {+19h 09m 24s}  -17.68d {-17d 40' 32"}
MOON_DIST:        99.65 [deg]
MOON_ILLUM:      8 [%]
GAL_COORDS:      276.60,-10.52 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      180.67,-70.70 [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 #15578
T. N. Ukwatta (MSU), V. D'Elia (ASDC), C. B. Markwardt (NASA/GSFC), A. Melandri (INAF-OAB), K. L. Page (U Leicester) and M. H. Siegel (PSU) report on behalf of the Swift Team:
At 09:18:38 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 131205A (trigger=580267). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 131.609, -60.174 which is
```
   RA(J2000) = 08h 46m 26s
   Dec(J2000) = -60d 10' 25"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multiple peaked structure with a duration of about 60 sec. The peak count rate was ~1300 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 09:20:07.5 UT, 88.7 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 131.6276, -60.1556 which is equivalent to:
```
   RA(J2000)  = 08h 46m 30.63s
   Dec(J2000) = -60d 09' 20.0"
```
with an uncertainty of 2.7 arcseconds (radius, 90% containment). This location is 74 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 1.50 x 10^21 cm^-2 (Kalberla et al. 2005).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 93 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 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 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 0.26.
We note that the spacecraft star tracker was out of lock during a portion of this GRB, but we believe the burst is real. The position may be revised after further processing.
Burst Advocate for this burst is T. N. Ukwatta (tilan.ukwatta AT gmail.com). 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 #15579
A. Klotz (IRAP-CNRS-OMP), D. Macpherson (UWA/ICRAR), D. Coward (UWA), D. Turpin (IRAP-CNRS-OMP), B. Gendre , M. Boer, K. Siellez, H. Dereli , O. Bardho (UNS-CNRS-OCA), A. Williams (PO-UWA), R. Martin (PO-UWA) report:
We imaged the field of GRB 131205A detected by SWIFT (trigger 580267) with the Zadko robotic telescope (D=100cm) located at the observatory - Gingin, Australia.
The observations started 3.74h after the GRB trigger which occured during Australian day time. The elevation of the field increased from 19 degrees above horizon and weather conditions were excellent.
We co-added a series of exposures but we do not detect any OT with a limiting magnitude of: t0+3.74h to t0+4.45h : Rlim = 20.2
Magnitudes were estimated with the nearby NOMAD1 stars and are not corrected for galactic dust extinction.
GCN Circular #15580
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team.
Using 2064 s of XRT Photon Counting mode data and 3 UVOT images for GRB 131205A, 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 = 131.62784, -60.15601 which is equivalent to:
```
RA (J2000): 08h 46m 30.68s
Dec (J2000): -60d 09' 21.6"
```
with an uncertainty of 2.0 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 #15581
C. A. Swenson (PSU) and T. N. Ukwatta (MSU) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 131205A 94 s after the BAT trigger (Ukwatta et al., GCN Circ. 15578). No optical afterglow consistent with the enhanced XRT position (Beardmore et al. GCN Circ. 15580) is detected in the initial UVOT exposures. Because the spacecraft attitude was not stable during the first finding chart exposure, we do not report on that exposure here.
Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the second finding chart (FC) exposure and subsequent exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s) Mag

u_FC               306          556          246 >20.8
white              586        12884         1171 >21.7
v                  636         6778          471 >20.5
b                  561        12313         1160 >21.5
u                  306        11400         1386 >22.0
w1                 685         7121          385 >20.4
m2                 660         6983          471 >20.4
w2                 611         6574          471 >20.6
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.26 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #15583
P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. Maselli (INAF-IASFPA), V. Mangano (PSU), M.C. Stroh (PSU), D.N. Burrows (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), C. Pagani (U. Leicester) and T.N. Ukwatta report on behalf of the Swift-XRT team:
We have analysed 10 ks of XRT data for GRB 131205A (Ukwatta et al. GCN Circ. 15578), from 226 s to 24.4 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN. Circ 15580).
The light curve can be modelled with a power-law decay with a decay index of alpha=1.10 (+0.09, -0.08).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.1 (+/-0.4). The best-fitting absorption column is 3.2 (+1.4, -1.2) x 10^21 cm^-2, in excess of the Galactic value of 1.5 x 10^21 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.9 x 10^-11 (6.8 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     3.2 (+1.4, -1.2) x 10^21 cm^-2
Galactic foreground: 1.5 x 10^21 cm^-2
Excess significance: 2.3 sigma
Photon index:	     2.1 (+/-0.4)
```
If the light curve continues to decay with a power-law decay index of 1.10, the count rate at T+24 hours will be 9.9 x 10^-4 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.8 x 10^-14 (6.7 x 10^-14) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00580267.
This circular is an official product of the Swift-XRT team.
GCN Circular #15584
T. Sakamoto (AGU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+771 sec from the recent telemetry downlink, we report further analysis of BAT GRB 131205A (trigger #580267) (Ukwatta, et al., GCN Circ. 15578). The BAT ground-calculated position is RA, Dec = 131.573, -60.181 deg which is
```
   RA(J2000)  =  08h 46m 17.6s 
   Dec(J2000) = -60d 10' 51.5" 
```
with an uncertainty of 2.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 95%.
The mask-weighted light curves two peaks starting at ~T-5, peaking at ~T+1, and ending at ~T+5 sec, and the second peak from ~T+18 to ~T+22 sec. T90 (15-350 keV) is 37.5 +- 9.6 sec (estimated error including systematics).
The time-averaged spectrum from T-18.50 to T+20.41 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.57 +- 0.38. The fluence in the 15-150 keV band is 2.9 +- 0.7 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T+19.30 sec in the 15-150 keV band is 0.6 +- 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/580267/BA/
GCN Circular #15585
S. Schmidl (TLS Tautenburg ), K. Varela and J. Greiner (both MPE Garching) report on behalf of the GROND team:
We observed the field of the GRB 131205A (Ukwatta et al., GCN #15578) simultaneously in g'r'i'z'JHKs with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at La Silla Observatory (Chile).
Observations started at 05:07 UT on 06 December 2013, 19.5 hours after the GRB. They were performed at an average seeing of 1.0" and at an average airmass of 1.3.
Based on six co-added observations with individual exposure times of 1500s in g'r'i'z' and 1200s in JHK, we do not detect any source inside the enhanced XRT error circle (Beardmore et al., GCN #15580) down to preliminary 3 sigma limiting magnitudes (all in the AB system) :
```
g' > 25.8 mag,
r' > 25.6 mag,
i' > 24.9 mag,
z' > 24.5 mag,
J > 22.1 mag,
H > 21.5 mag,
K > 20.8 mag.
```
Magnitudes are calibrated against GROND zeropoints (griz) and 2MASS stars (JHK), and are not corrected for the Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.25 mag in the direction of the burst (Schlegel et al. 1998).
We note the marginal detection of a source, located 1.9" from the center of the XRT circle, at
```
RA : 08:46:30.86
DEC : -60:09:20.6,
```
with an uncertainty of 0.2 arcsec and magnitudes of
```
r = 24.8 +/- 0.2
i = 24.7 +/- 0.3
z = 24.3 +/- 0.3.
```
This is consistent with a power law and thus could be the afterglow of GRB 131205A, but no statement can be made about fading at this time. Follow-up observations are required to determine the nature of this source.
GCN Circular #15595
K. Varela, D.A. Kann and J. Greiner (all MPE Garching) report on behalf of the GROND team:
We observed again the field of the GRB 131205A (Ukwatta et al., GCN #15578) simultaneously in g'r'i'z'JHKs with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at the La Silla Observatory (Chile).
Observations started at 05:22 UT on 11 December 2013. They were performed at an average seeing of 0.7 arcsec and at an average airmass of 1.3.
Based on four co-added observations with individual exposure times of 2214s in g'r'i'z' and 1800s in JHKs, we measure for the source at the border of the X-ray error circle (Beardmore et al., GCN #15580), which was proposed as potential counterpart (Schmidl et al. 2013, GCN #15585), the following magnitudes:
```
r' = 26.5 +/- 0.4
i' = 25.3 +/- 0.4
```
Compared to our earlier measurements of r' = 24.8+/-0.2, i' = 24.7+/-0.3 this implies a fading of 1.7+/-0.5 in r', and 0.6+/-0.5 in i'. We conclude that the fading in r' is significant, and propose this source as the optical counterpart of GRB 131205A. The low amplitude in the i'-band may be caused by the emergence of light from a red host galaxy. Observations with bigger glasses are required to verify this interpretation.
Note that the above r'i' magnitudes are calibrated against GROND zeropoints and are not corrected for the Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.25 mag in the direction of the burst (Schlegel et al. 1998).

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Jochen Greiner, last update: 13-Dec-2013 [Disclaimer]