Gamma-ray Burst 081121

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Fri 21 Nov 08 20:35:43 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      47
TRIGGER_NUM:     248992528
GRB_RA:          106.917d {+07h 07m 40s} (J2000),
                 106.917d {+07h 07m 40s} (current),
                 106.914d {+07h 07m 39s} (1950)
GRB_DEC:         -67.367d {-67d 21' 59"} (J2000),
                 -67.381d {-67d 22' 51"} (current),
                 -67.286d {-67d 17' 07"} (1950)
GRB_ERROR:       18.05 [deg radius, statistical only]
GRB_INTEN:       151 [cnts/sec]
DATA_SIGNIF:     5.40 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        14791 TJD;   326 DOY;   08/11/21
GRB_TIME:        74127.75 SOD {20:35:27.75} UT
GRB_PHI:         158.00 [deg]
GRB_THETA:       145.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      0.50
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      80%  GRB
2nd_MOST_LIKELY:   9%  Distant Particles
DETECTORS:       0,0,0, 0,0,0, 0,0,0, 0,1,1, 0,0,
SUN_POSTN:       237.73d {+15h 50m 55s}  -20.13d {-20d 07' 48"}
SUN_DIST:         85.31 [deg]   Sun_angle= 8.7 [hr] (West of Sun)
MOON_POSTN:      172.94d {+11h 31m 47s}   -0.56d {-00d 33' 47"}
MOON_DIST:        80.48 [deg]
MOON_ILLUM:      30 [%]
GAL_COORDS:      278.21,-23.37 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      194.68,-83.35 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 6.87,6.87 [deg].

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Fri 21 Nov 08 20:35:50 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      57
TRIGGER_NUM:     248992528
GRB_RA:          112.783d {+07h 31m 08s} (J2000),
                 112.807d {+07h 31m 14s} (current),
                 112.650d {+07h 30m 36s} (1950)
GRB_DEC:         -63.217d {-63d 12' 59"} (J2000),
                 -63.236d {-63d 14' 08"} (current),
                 -63.109d {-63d 06' 32"} (1950)
GRB_ERROR:       6.53 [deg radius, statistical only]
GRB_INTEN:       403 [cnts/sec]
DATA_SIGNIF:     18.70 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        14791 TJD;   326 DOY;   08/11/21
GRB_TIME:        74127.75 SOD {20:35:27.75} UT
GRB_PHI:         167.00 [deg]
GRB_THETA:       145.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      0.00
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:     100%  Below horizon
2nd_MOST_LIKELY:   0%  n/a
DETECTORS:       0,0,0, 0,0,0, 0,0,0, 0,1,1, 0,0,
SUN_POSTN:       237.73d {+15h 50m 55s}  -20.13d {-20d 07' 49"}
SUN_DIST:         86.26 [deg]   Sun_angle= 8.3 [hr] (West of Sun)
MOON_POSTN:      172.95d {+11h 31m 47s}   -0.56d {-00d 33' 48"}
MOON_DIST:        76.53 [deg]
MOON_ILLUM:      30 [%]
GAL_COORDS:      274.79,-19.75 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      171.50,-79.84 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 6.87,6.87 [deg].

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Fri 21 Nov 08 20:35:56 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      68
TRIGGER_NUM:     248992528
GRB_RA:          101.400d {+06h 45m 36s} (J2000),
                 101.421d {+06h 45m 41s} (current),
                 101.280d {+06h 45m 07s} (1950)
GRB_DEC:         -62.350d {-62d 21' 00"} (J2000),
                 -62.360d {-62d 21' 34"} (current),
                 -62.295d {-62d 17' 42"} (1950)
GRB_ERROR:       5.78 [deg radius, statistical only]
GRB_INTEN:       348 [cnts/sec]
DATA_SIGNIF:     21.70 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        14791 TJD;   326 DOY;   08/11/21
GRB_TIME:        74127.75 SOD {20:35:27.75} UT
GRB_PHI:         164.00 [deg]
GRB_THETA:       140.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      0.63
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      65%  GRB
2nd_MOST_LIKELY:  26%  Distant Particles
DETECTORS:       0,0,0, 0,0,0, 0,0,0, 0,1,1, 0,0,
SUN_POSTN:       237.73d {+15h 50m 55s}  -20.13d {-20d 07' 49"}
SUN_DIST:         90.58 [deg]   Sun_angle= 9.1 [hr] (West of Sun)
MOON_POSTN:      172.95d {+11h 31m 47s}   -0.56d {-00d 33' 50"}
MOON_DIST:        81.04 [deg]
MOON_ILLUM:      30 [%]
GAL_COORDS:      272.28,-24.48 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      144.67,-83.54 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 6.87,6.87 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 21 Nov 08 20:36:12 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     335105,   Seg_Num: 0
GRB_RA:           89.264d {+05h 57m 03s} (J2000),
                  89.290d {+05h 57m 10s} (current),
                  89.118d {+05h 56m 28s} (1950)
GRB_DEC:         -60.626d {-60d 37' 32"} (J2000),
                 -60.625d {-60d 37' 29"} (current),
                 -60.630d {-60d 37' 46"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       18126 [cnts]    Image_Peak=241 [image_cnts]
TRIGGER_DUR:     4.096 [sec] 
TRIGGER_INDEX:   307     E_range: 50-350 keV
BKG_INTEN:       122067 [cnts]
BKG_TIME:        74076.72 SOD {20:34:36.72} UT
BKG_DUR:         40 [sec]
GRB_DATE:        14791 TJD;   326 DOY;   08/11/21
GRB_TIME:        74132.85 SOD {20:35:32.85} UT
GRB_PHI:          -9.26 [deg]
GRB_THETA:        57.73 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     39.31 [sigma]
IMAGE_SIGNIF:    9.79 [sigma]
MERIT_PARAMS:     +1  +0  +0  +3  +3 +15  +0  +0  +9  +0 
SUN_POSTN:       237.73d {+15h 50m 55s}  -20.13d {-20d 07' 49"}
SUN_DIST:         95.31 [deg]   Sun_angle= 9.9 [hr] (West of Sun)
MOON_POSTN:      172.95d {+11h 31m 48s}   -0.57d {-00d 33' 54"}
MOON_DIST:        86.40 [deg]
MOON_ILLUM:      30 [%]
GAL_COORDS:      269.53,-30.00 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       86.51,-84.06 [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 = 186.66,4.50 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Fri 21 Nov 08 20:36:45 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      67
TRIGGER_NUM:     248992528
GRB_RA:           77.880d {+05h 11m 31s} (J2000),
                  77.897d {+05h 11m 35s} (current),
                  77.784d {+05h 11m 08s} (1950)
GRB_DEC:         -63.420d {-63d 25' 11"} (J2000),
                 -63.410d {-63d 24' 34"} (current),
                 -63.479d {-63d 28' 42"} (1950)
GRB_ERROR:       3.37 [deg radius, statistical only]
DATA_SIGNIF:     28.50 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        14791 TJD;   326 DOY;   08/11/21
GRB_TIME:        74127.75 SOD {20:35:27.75} UT
GRB_PHI:         152.00 [deg]
GRB_THETA:       133.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   1 (Gnd S/W Version number)
SUN_POSTN:       237.73d {+15h 50m 55s}  -20.13d {-20d 07' 49"}
SUN_DIST:         94.98 [deg]   Sun_angle= 10.7 [hr] (West of Sun)
MOON_POSTN:      172.95d {+11h 31m 49s}   -0.57d {-00d 34' 02"}
MOON_DIST:        91.75 [deg]
MOON_ILLUM:      30 [%]
GAL_COORDS:      273.19,-35.17 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       25.91,-84.00 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Fri 21 Nov 08 20:36:48 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      70
TRIGGER_NUM:     248992528
GRB_RA:           73.240d {+04h 52m 58s} (J2000),
                  73.289d {+04h 53m 09s} (current),
                  72.968d {+04h 51m 52s} (1950)
GRB_DEC:         -54.070d {-54d 04' 11"} (J2000),
                 -54.056d {-54d 03' 20"} (current),
                 -54.151d {-54d 09' 02"} (1950)
GRB_ERROR:       3.64 [deg radius, statistical only]
DATA_SIGNIF:     21.90 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        14791 TJD;   326 DOY;   08/11/21
GRB_TIME:        74127.75 SOD {20:35:27.75} UT
GRB_PHI:         157.00 [deg]
GRB_THETA:       124.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   1 (Gnd S/W Version number)
SUN_POSTN:       237.73d {+15h 50m 55s}  -20.13d {-20d 07' 49"}
SUN_DIST:        104.61 [deg]   Sun_angle= 11.0 [hr] (West of Sun)
MOON_POSTN:      172.95d {+11h 31m 49s}   -0.57d {-00d 34' 03"}
MOON_DIST:        95.19 [deg]
MOON_ILLUM:      30 [%]
GAL_COORDS:      262.01,-38.85 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       48.82,-75.11 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 21 Nov 08 20:39:16 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     335105,   Seg_Num: 0
GRB_RA:           89.264d {+05h 57m 03s} (J2000),
                  89.290d {+05h 57m 10s} (current),
                  89.118d {+05h 56m 28s} (1950)
GRB_DEC:         -60.626d {-60d 37' 32"} (J2000),
                 -60.625d {-60d 37' 29"} (current),
                 -60.630d {-60d 37' 46"} (1950)
GRB_DATE:        14791 TJD;   326 DOY;   08/11/21
GRB_TIME:        74132.85 SOD {20:35:32.85} UT
TRIGGER_INDEX:   307
GRB_PHI:          -9.26 [deg]
GRB_THETA:        57.73 [deg]
DELTA_TIME:      -11.00 [sec]
TRIGGER_DUR:     4.096 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     39.31 [sigma]
IMAGE_SIGNIF:    9.79 [sigma]
LC_URL:          sw00335105000msb.lc
SUN_POSTN:       237.73d {+15h 50m 55s}  -20.13d {-20d 07' 50"}
SUN_DIST:         95.31 [deg]   Sun_angle= 9.9 [hr] (West of Sun)
MOON_POSTN:      172.97d {+11h 31m 53s}   -0.58d {-00d 34' 39"}
MOON_DIST:        86.40 [deg]
MOON_ILLUM:      30 [%]
GAL_COORDS:      269.53,-30.00 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       86.51,-84.06 [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 = 186.66,4.50 [deg].

GCN Circular #8536
F. Yuan (U Mich), W. Rujopakarn (Steward) report on behalf of the ROTSE collaboration:
ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia, responded to GRB 081121 (Swift trigger 335105). The first image was at 20:36:30.0 UT, 57.2 s after the burst (8.9 s after the GCN notice time). The unfiltered images are calibrated relative to USNO A2.0. We detect a 11.6 magnitude, fading source with coordinates:
05:57:06.1 -60:36:10.3 (J2000), with positional uncertainty of 1" or better
```
start UT    	mag     mlim(of image)
----------------------------------
20:36:29.9     11.6     15.7 
```
This source is not visible in DSS (second epoch), 2MASS or the MPChecker database.
A jpeg image is available at http://www.rotse.net/images/gsb335105_3c00_img.jpg Note that the object marked 4 is the candidate in question.
Continuing observations are in progress.
GCN Circular #8537
S. R. Oates (UCL-MSSL), W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester), N. Gehrels (NASA/GSFC), O. Godet (U Leicester), S. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU), H. A. Krimm (CRESST/GSFC/USRA), C. B. Markwardt (CRESST/GSFC/UMD), P. T. O'Brien (U Leicester), C. Pagani (PSU), K. L. Page (U Leicester), D. M. Palmer (LANL), P. Schady (MSSL-UCL), M. Stamatikos (NASA/ORAU), R. L. C. Starling (U Leicester), L. Vetere (PSU) and H. Ziaeepour (UCL-MSSL) report on behalf of the Swift Team:
At 20:35:32 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 081121 (trigger=335105). Due to an Earth limb constraint slew could not immediately slew to this burst. The BAT on-board calculated location is RA, Dec 89.264, -60.626 which is
```
   RA(J2000) = 05h 57m 03s
   Dec(J2000) = -60d 37' 32"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single FRED structure with a duration of about 15 sec, with overlying spikes. There may be continued low-level emission out to 100 seconds. The peak count rate was ~4000 counts/sec (15-350 keV), at ~1.5 sec after the trigger.
Due to an observing constraint, Swift will not slew until T0+45.2 minutes. There will be no XRT or UVOT data until this time.
Burst Advocate for this burst is S. R. Oates (sro AT mssl.ucl.ac.uk). 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:     Fri 21 Nov 08 21:22:33 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     335105,   Seg_Num: 0
POINT_RA:         89.227d {+05h 56m 55s} (J2000)
POINT_DEC:       -60.615d {-60d 36' 52"} (J2000)
IMG_START_DATE:  14791 TJD;   326 DOY;   08/11/21
IMG_START_TIME:  76946.05 SOD {21:22:26.05} UT,   2813.2 [sec] since BAT Trigger Time
COUNTS:          10    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:     Fri 21 Nov 08 21:25:23 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     335105,   Seg_Num: 0
POINT_RA:         89.228d {+05h 56m 55s} (J2000)
POINT_DEC:       -60.615d {-60d 36' 52"} (J2000)
POINT_ROLL:      150.467d
IMG_START_DATE:  14791 TJD;   326 DOY;   08/11/21
IMG_START_TIME:  76948.49 SOD {21:22:28.49} UT,   2815.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.587
N_STARS:         131
X_OFFSET:        542 [pixels]
Y_OFFSET:        416 [pixels]
X_MAX:           1501 [pixels]
Y_MAX:           1375 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw00335105000msufc2815.fits
SUN_POSTN:       237.76d {+15h 51m 03s}  -20.14d {-20d 08' 15"}
SUN_DIST:         95.33 [deg]   Sun_angle= 9.9 [hr] (West of Sun)
MOON_POSTN:      173.34d {+11h 33m 21s}   -0.77d {-00d 46' 00"}
MOON_DIST:        86.43 [deg]
MOON_ILLUM:      29 [%]
GAL_COORDS:      269.52,-30.02 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       86.35,-84.04 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 21 Nov 08 21:25:56 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     335105,   Seg_Num: 0
POINT_RA:         89.228d {+05h 56m 55s} (J2000)
POINT_DEC:       -60.615d {-60d 36' 52"} (J2000)
POINT_ROLL:      150.467d
IMG_START_DATE:  14791 TJD;   326 DOY;   08/11/21
IMG_START_TIME:  76948.49 SOD {21:22:28.49} UT,   2815.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.587
N_STARS:         131
X_OFFSET:        542 [pixels]
Y_OFFSET:        416 [pixels]
X_MAX:           1501 [pixels]
Y_MAX:           1375 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw00335105000msufc2815.fits
SUN_POSTN:       237.76d {+15h 51m 03s}  -20.14d {-20d 08' 15"}
SUN_DIST:         95.33 [deg]   Sun_angle= 9.9 [hr] (West of Sun)
MOON_POSTN:      173.34d {+11h 33m 22s}   -0.77d {-00d 46' 07"}
MOON_DIST:        86.43 [deg]
MOON_ILLUM:      29 [%]
GAL_COORDS:      269.52,-30.02 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       86.35,-84.04 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 21 Nov 08 21:26:40 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     335105,   Seg_Num: 0
POINT_RA:         89.228d {+05h 56m 55s} (J2000)
POINT_DEC:       -60.615d {-60d 36' 52"} (J2000)
ROLL:            150.467d
IMG_START_DATE:  14791 TJD;   326 DOY;   08/11/21
IMG_START_TIME:  76948.49 SOD {21:22:28.49} UT,   2815.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     248995351
X_OFFSET:        861 [pixels]
Y_OFFSET:        735 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1021
Y_GRB_POS:       895
BINNING_INDEX:   1
IM_URL:          sw00335105000msuni2815.fits
SUN_POSTN:       237.76d {+15h 51m 04s}  -20.14d {-20d 08' 16"}
SUN_DIST:         95.33 [deg]   Sun_angle= 9.9 [hr] (West of Sun)
MOON_POSTN:      173.35d {+11h 33m 24s}   -0.77d {-00d 46' 18"}
MOON_DIST:        86.43 [deg]
MOON_ILLUM:      29 [%]
GAL_COORDS:      269.52,-30.02 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       86.35,-84.04 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 21 Nov 08 21:27:07 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     335105,   Seg_Num: 0
POINT_RA:         89.228d {+05h 56m 55s} (J2000)
POINT_DEC:       -60.615d {-60d 36' 52"} (J2000)
ROLL:            150.467d
IMG_START_DATE:  14791 TJD;   326 DOY;   08/11/21
IMG_START_TIME:  76948.49 SOD {21:22:28.49} UT,   2815.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     248995351
X_OFFSET:        861 [pixels]
Y_OFFSET:        735 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1021
Y_GRB_POS:       895
BINNING_INDEX:   1
IM_URL:          sw00335105000msuni2815.fits
SUN_POSTN:       237.77d {+15h 51m 04s}  -20.14d {-20d 08' 16"}
SUN_DIST:         95.33 [deg]   Sun_angle= 9.9 [hr] (West of Sun)
MOON_POSTN:      173.35d {+11h 33m 25s}   -0.77d {-00d 46' 25"}
MOON_DIST:        86.43 [deg]
MOON_ILLUM:      29 [%]
GAL_COORDS:      269.52,-30.02 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       86.35,-84.04 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        If you have elected to receive attachments:  
COMMENTS:        The uvot_sources_image.fits.gz file does not exist; skipping the attachment.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 21 Nov 08 21:27:09 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     335105,   Seg_Num: 0
GRB_RA:           89.2747d {+05h 57m 05.92s} (J2000),
                  89.3008d {+05h 57m 12.18s} (current),
                  89.1283d {+05h 56m 30.79s} (1950)
GRB_DEC:         -60.6024d {-60d 36' 08.6"} (J2000),
                 -60.6018d {-60d 36' 06.4"} (current),
                 -60.6063d {-60d 36' 22.6"} (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:  14791 TJD;   326 DOY;   08/11/21
IMG_START_TIME:  76961.00 SOD {21:22:41.00} UT,   2828.1 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       237.77d {+15h 51m 04s}  -20.14d {-20d 08' 16"}
SUN_DIST:         95.33 [deg]   Sun_angle= 9.9 [hr] (West of Sun)
MOON_POSTN:      173.35d {+11h 33m 25s}   -0.77d {-00d 46' 25"}
MOON_DIST:        86.41 [deg]
MOON_ILLUM:      29 [%]
GAL_COORDS:      269.50,-29.99 [deg] galactic lon,lat of the burst
ECL_COORDS:       86.57,-84.03 [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.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 21 Nov 08 21:29:31 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     335105,   Seg_Num: 0
GRB_RA:           89.2759d {+05h 57m 06.21s} (J2000),
                  89.3020d {+05h 57m 12.47s} (current),
                  89.1295d {+05h 56m 31.08s} (1950)
GRB_DEC:         -60.6030d {-60d 36' 10.8"} (J2000),
                 -60.6024d {-60d 36' 08.5"} (current),
                 -60.6069d {-60d 36' 24.7"} (1950)
GRB_ERROR:       3.3 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  14791 TJD;   326 DOY;   08/11/21
IMG_START_TIME:  76961.00 SOD {21:22:41.00} UT,   2828.1 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       237.77d {+15h 51m 04s}  -20.14d {-20d 08' 17"}
SUN_DIST:         95.33 [deg]   Sun_angle= 9.9 [hr] (West of Sun)
MOON_POSTN:      173.37d {+11h 33m 29s}   -0.78d {-00d 47' 00"}
MOON_DIST:        86.41 [deg]
MOON_ILLUM:      29 [%]
GAL_COORDS:      269.50,-29.99 [deg] galactic lon,lat of the burst
ECL_COORDS:       86.58,-84.03 [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.

GCN Circular #8538
S. R. Oates and P. Schady (MSSL-UCL) report on behalf of the Swift UVOT team:
The Swift/UVOT began observing the field of GRB081121 starting 2816 seconds after the BAT trigger (Oates et al., GCN 8537) with a White finding chart exposure of 150 seconds. There is a candidate afterglow in the 2.7'x2.7' sub- image at
```
RA(J2000) =	05:57:06.19 = 89.27581
DEC(J2000) = -60:36:10.3 = -60.60286
```
with a 90%-confidence error radius of about 0.62 arc sec. This position is 0.7 arc sec. from the center of the XRT error circle and is consistent with the position of the optical afterglow found by ROTSE-IIIc (Yuan el al., GCN 8536).
The estimated magnitude is 17.98 with a 1-sigma error of about 0.04. No correction has been made for the expected extinction corresponding to E(B-V) of 0.05.
GCN Circular #8539
T. Sakamoto (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), S. R. Oates (UCL-MSSL), D. M. Palmer (LANL), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team):
Using the data set from T-119 to T+271 sec from the recent telemetry downlink, we report further analysis of BAT GRB 081121 (trigger #335105) (Oates, et al., GCN Circ. 8537). The BAT ground-calculated position is RA, Dec = 89.282, -60.612 deg, which is
```
   RA(J2000)  =  05h 57m 07.7s 
   Dec(J2000) = -60d 36' 42.1" 
```
with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 5%.
The mask-weighted light curve shows an approximately square-shaped pulse with a trailing spike. The pulse starts at ~T-10 sec and ends at ~T=15 sec. There is a hint of low-level precursor emission starting before T-119 sec (the beginning of the saved event-by-event data). T90 (15-350 keV) is 14 +- 2 sec (estimated error including systematics).
The time-averaged spectrum from T-2.8 to T+12.9 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.43 +- 0.54, and Epeak of 123 +- 69 keV (chi squared 44.9 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 4.1 +- 0.3 x 10^-6 erg/cm2 and the 1-sec peak flux measured from T+6.94 sec in the 15-150 keV band is 4.4 +- 1.0 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.21 +- 0.12 (chi squared 52.0 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/335105/BA/
GCN Circular #8540
S. Loew, T. Kruehler and J. Greiner (all MPE Garching) report on behalf of the GROND team:
We observed the field of GRB 081121 (Swift trigger #335105; Oates et al., GCN #8537) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m ESO/MPI telescope at La Silla Observatory (Chile).
Observations started at 00:30 UT on November 22nd, 2008, 3.9 hr after the burst at a high airmass of 2.35, and are continuing.
We detect the optical afterglow reported by Yuan et al. (GCN #8536) and Oates & Schady (GCN #8538) clearly in all filters.
At a midtime of 3.9454 hours after the burst, we estimate the following preliminary magnitudes (all in AB system) in stacked images of 4 x 35s integration in g'r'i'z' and 24 x 10s integration in JHK:
```
g' = 19.1
r' = 18.8
i' = 18.6
z' = 18.5
J  = 18.4
H  = 18.2
K  = 18.1 
```
with typical errors of 0.2 mag, which are mostly due to a preliminary calibration using GROND zeropoints in g'r'i'z' and 2MASS field stars in JHK.
GCN Circular #8541
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team.
Using 939 s of XRT Photon Counting mode data and 3 UVOT images for GRB 081121, 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 = 89.2757, -60.6028 which is equivalent to:
```
RA (J2000): 05h 57m 6.17s
Dec (J2000): -60d 36' 10.1"
```
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 http://www.swift.ac.uk/xrt_positions/Goad.pdf), the current algorithm is an extension of this method.
This circular was automatically generated, and is an official product of the Swift-XRT team.
GCN Circular #8542
E. Berger (Harvard) and M. Rauch (Carnegie) report:
"We obtained spectroscopic observations of the optical afterglow of GRB 081121 (GCNs 8536,8537) with the LDSS3 spectrograph on the Magellan/Clay 6.5-m telescope starting on 2008 Nov 22.16 UT. The spectra cover the wavelength range 3800-6500A. We detect Ly-alpha absorption, as well as aborption features corresponding to SiII, CII, SiIV, CIV, FeII, and AlII at a redshift of z=2.512, which we consider the redshift of the burst. Further analysis is in progress."
GCN Circular #8543
O. Godet (U Leicester) and S. Oates (UCL-MSSL) on behalf the Swift-XRT team:
The Swift-XRT started observing the field of GRB 081121 (trigger number 335105, Oates et al., GCN Circ. 8537) at 2008-11-21 20:35:32 UT, 2.8 ks after the trigger. The best XRT position is the UVOT-enhanced position reported by Goad et al. (GCN Circ. 8541). This position is consistent with the optical positions reported by the Swift-UVOT and ROTSE III (Oates et al., GCN Circ. 8538; Yuan et al., GCN Circ. 8536).
The X-ray light curve presently spans 4.2 ks of photon counting (PC) mode data from T+2.8 ks to T+16 ks. The light curve shows an initial decay with a slope of 1.11 +0.06/-0.05 up to at least ~T+17 ks, followed by a steep decay up to ~T+20 ks and then a flatter decay with a slope of 0.25 +0.62/-0.13.
The PC X-ray spectrum from the same interval can be well fit by an absorbed power-law with a photon index of 1.99 +0.10/-0.09 and a column density of (9.7 +2.2/-2.0) x 10^20 cm^-2 (the Galactic value is 4.0 x 10^20 cm^-2 in the direction of the burst). The observed 0.3-10.0 keV flux is (7.1 +/-0.4) x 10^-11 erg cm^-2 s^-1 which corresponds to an unabsorbed flux of (9.0 +0.2/-0.5) x 10^-11 erg cm^-2 s^-1.
If the burst continues on the current plateau phase, the predicted count rate at T+1 day would be approximately 1.2 x 10^-1 count s^-1.
This is an official product of the Swift-XRT team.
GCN Circular #8544
S. R. Oates (MSSL-UCL) reports on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 081121, 2816s after the BAT trigger (Oates et al., GCN Circ. 8537). We detect the optical afterglow in the white, v, b, u filters and marginally in the uvw1 filter at the position:
```
RA(J2000.0)  =   5:57:06.15
DEC(J2000.0) = -60:36:10.0
```
with an estimated uncertainty of 0.6 arcsec (radius, 90% confidence). This position is consistent with the UVOT-enhanced XRT position and the position reported by ROTSE-IIIC (Yuan et al., GCN Circ. 8536).
The marginal detection of the optical afterglow in uvw1, and the lack of a detection in the uvm2 and uvw2 filters is consistent with a redshift of z=2.512 reported by Magellan (Berger and Rauch, GCN Circ. 8542).
The magnitudes and 3 sigma upper limits are reported below:
```
Filter    T_start (s) T_stop  Exposure      Mag/3sig UL
---------------------------------------------------------
white       2816       2965     147       17.93 +/- 0.04
v           2972       3172     197       17.58 +/- 0.08
b           3792       3992     197       18.26 +/- 0.07
u           3587       3787     197       17.62 +/- 0.06
uvw1        3383       3582     197       20.60 +/- 0.48 (2.3-sigma)
uvm2        3177       4813     393       > 20.09
uvw2        4203       11200    790       > 20.78
---------------------------------------------------------
```
The above magnitudes are not corrected for the Galactic extinction corresponding to a reddening of E_{B-V} = 0.05 mag (Schlegel et al., 1998, ApJS, 500, 525). The photometry is on the UVOT flight system described in Poole et al. (2008, MNRAS, 383,627).
GCN Circular #8546
Colleen A. Wilson-Hodge (NASA/MSFC) and Valerie Connaughton (UAH) report on behalf of the Fermi GBM Team:
"At 20:35:27.5 UT on 21 November 2008, the Fermi Gamma-Ray Burst Monitor triggered on GRB 081121 (trigger 248992528/ 081121.858). This burst triggered Swift-BAT 4 seconds later (Oates et al 2008, GCN 8537) and an optical counterpart was detected with ROTSE-III (Yuan et al. 2008, GCN 8536). The burst direction was 135 degrees from the Fermi pointing-axis so the Fermi GBM sensitivity to this GRB is limited. Further analysis is necessary to provide meaningful spectral information about this burst.
Final spectral analysis results will be published in the GBM GRB Catalog."
GCN Circular #8547
B. E. Cobb (UC Berkeley) reports:
Using the ANDICAM instrument on the 1.3m telescope at CTIO, we obtained several epochs of optical/IR imaging of the error region of GRB 081121 (GCN 8537, Oates et al.). Each epoch consisted of several dithered images in each filter, with total summed exposure times of 180s in each of BRIJK and 120s in each of H and V.
```
At a mid-exposure time of 2008-11-22 02:02 (5.4 hrs post-burst),
the GRB afterglow (GCN 8536, Yuan et al.) is detected with the
following magnitudes:
B = 19.34 +/- 0.04
R = 18.61 +/- 0.04
I = 18.21 +/- 0.04
J = 17.21 +/- 0.15
H = 17.05 +/- 0.15
K = 16.75 +/- 0.15
```
Observations were obtained under non-photometric conditions. In optical, these preliminary magnitudes are calibrated against several USNO-B1.0 stars in the field, so there is likely an additional photometric calibration error of ~0.3 magnitudes. In the IR, calibration is against 2MASS stars.
Between 5.4 hrs and 8.7 hours post-burst, the afterglow decays with an approximate optical decay rate of alpha~-1 (where afterglow flux is proportional to t^alpha).
GCN Circular #8548
S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, P. Oleynik, D. Svinkin, M. Ulanov and T. Cline, on behalf of the Konus-Wind team report:
The long GRB 081121 (Swift-BAT trigger #335105: Oates et al., GCN 8537, Sakamoto et al. 8539) triggered Konus-Wind at T0=74131.435 s UT (20:35:31.435).
The burst light curve shows a multipeaked structure with a total duration of ~18 s.
As observed by Konus-Wind the burst had a fluence of 1.79(-0.31, +0.37)x10^-5 erg/cm2, and a 256-ms peak flux measured from T0+16.368 s of 2.60(-0.63, +0.70)x10^-6 erg/cm2/s (both in the 20 keV - 7 MeV energy range).
The time-integrated spectrum of the burst (from T0 to T0+16.640 s) is well be fitted (in the 20 keV - 7 MeV range) by GRB (Band) model for which: the low-energy photon index is alpha = -0.77(-0.14, +0.15), the high energy photon index beta = -2.51(-0.66, +0.31), the peak energy Ep = 248(-32, +38) keV (chi2 = 92.3/79 dof).
All the quoted errors are at the 90% confidence level.
Assuming z = 2.512 (Berger & Rauch, GCN 8542) and a standard cosmology model with H_0 = 70 km/s/Mpc, Omega_M = 0.27, Omega_\Lambda = 0.73, the isotropic energy release E_iso ~2.7x10^53 erg, the peak luminosity (L_iso)_max ~ 1.4x10^53 erg/s, and Ep_rest ~870 keV.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.rssi.ru/LEA/GRBs/GRB081121_T74131/
GCN Circular #8643
Aquib Moin (Curtin Institute of Radio Astronomy / Australia Telescope National Facility), Steven Tingay (Curtin Institute of Radio Astronomy), Chris Phillips (Australia Telescope National Facility), Gregory Taylor (University of New Mexico), Mark Wieringa (Australia Telescope National Facility) and Ralph Martin (Perth Observatory) report:
We observed the SWIFT-UVOT refined position of the GRB 081121 optical afterglow (GCN 8544) at 4.800 and 4.928 GHz with the Australia Telescope Compact Array (ATCA) between 01:15:05 UT, November 24, 2008 and 20:35:30 UT, November 25, 2008.
We did not detect a radio source at the optical afterglow position of the GRB 081121 (GCN 8544). The data at 4.800 and 4.928 GHz were merged and the radio flux density at the afterglow position found out to be 0.106 +/- 0.208 mJy/beam (1-sigma).
The Australia Telescope Compact Array (/ Parkes telescope / Mopra telescope / Long Baseline Array) is part of the Australia Telescope which is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO.
See the 4.800 & 4.928 GHz combined image at:
http://cira.ivec.org/dokuwiki/doku.php/grb/grb081121_field_image
GCN Report 182.1
GCN_Report 182.1 has been posted: http://gcn.gsfc.nasa.gov/reports/report_182_1.pdf by S.R. Oates at MSSL-UCL titled: "Final Swift report on GRB 081121"

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Jochen Greiner, last update: 20-Dec-2008 [Disclaimer]