Gamma-ray Burst 081221

(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:     Sun 21 Dec 08 16:21:27 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     337889,   Seg_Num: 0
GRB_RA:           15.805d {+01h 03m 13s} (J2000),
                  15.914d {+01h 03m 39s} (current),
                  15.199d {+01h 00m 48s} (1950)
GRB_DEC:         -24.526d {-24d 31' 32"} (J2000),
                 -24.478d {-24d 28' 39"} (current),
                 -24.794d {-24d 47' 38"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       2755 [cnts]    Image_Peak=152 [image_cnts]
TRIGGER_DUR:     0.512 [sec] 
TRIGGER_INDEX:   124     E_range: 25-100 keV
BKG_INTEN:       33440 [cnts]
BKG_TIME:        58860.64 SOD {16:21:00.64} UT
BKG_DUR:         8 [sec]
GRB_DATE:        14821 TJD;   356 DOY;   08/12/21
GRB_TIME:        58871.84 SOD {16:21:11.84} UT
GRB_PHI:          37.50 [deg]
GRB_THETA:        27.14 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     12.84 [sigma]
IMAGE_SIGNIF:    8.37 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +2 +16  +0  +0  +5  +0 
SUN_POSTN:       270.20d {+18h 00m 48s}  -23.44d {-23d 26' 14"}
SUN_DIST:         93.52 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      202.46d {+13h 29m 50s}  -14.83d {-14d 49' 49"}
MOON_DIST:       140.18 [deg]
MOON_ILLUM:      28 [%]
GAL_COORDS:      169.12,-86.29 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:        4.07,-28.65 [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 = 62.16,17.61 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sun 21 Dec 08 16:21:33 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      49
TRIGGER_NUM:     251569273
GRB_RA:           21.667d {+01h 26m 40s} (J2000),
                  21.775d {+01h 27m 06s} (current),
                  21.062d {+01h 24m 15s} (1950)
GRB_DEC:         -19.617d {-19d 36' 59"} (J2000),
                 -19.570d {-19d 34' 12"} (current),
                 -19.876d {-19d 52' 32"} (1950)
GRB_ERROR:       11.87 [deg radius, statistical plus systematic]
GRB_INTEN:       218 [cnts/sec]
DATA_SIGNIF:     11.30 [sigma]
INTEG_TIME:      1.024 [sec]
GRB_DATE:        14821 TJD;   356 DOY;   08/12/21
GRB_TIME:        58872.22 SOD {16:21:12.22} UT
GRB_PHI:          59.00 [deg]
GRB_THETA:        70.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO:      0.39
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      97%  GRB
2nd_MOST_LIKELY:   2%  Generic Transient
DETECTORS:       0,0,1, 0,0,1, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       270.20d {+18h 00m 48s}  -23.44d {-23d 26' 14"}
SUN_DIST:        100.64 [deg]   Sun_angle= -7.4 [hr] (East of Sun)
MOON_POSTN:      202.46d {+13h 29m 51s}  -14.83d {-14d 49' 50"}
MOON_DIST:       145.59 [deg]
MOON_ILLUM:      28 [%]
GAL_COORDS:      171.87,-78.97 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       11.97,-26.51 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 116.23,-5.35 [deg].

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sun 21 Dec 08 16:21:44 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      59
TRIGGER_NUM:     251569273
GRB_RA:           15.583d {+01h 02m 20s} (J2000),
                  15.691d {+01h 02m 46s} (current),
                  14.982d {+00h 59m 56s} (1950)
GRB_DEC:         -27.967d {-27d 57' 59"} (J2000),
                 -27.918d {-27d 55' 06"} (current),
                 -28.235d {-28d 14' 06"} (1950)
GRB_ERROR:       7.45 [deg radius, statistical plus systematic]
GRB_INTEN:       207 [cnts/sec]
DATA_SIGNIF:     20.50 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        14821 TJD;   356 DOY;   08/12/21
GRB_TIME:        58872.22 SOD {16:21:12.22} UT
GRB_PHI:          62.00 [deg]
GRB_THETA:        80.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      1.33
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      60%  GRB
2nd_MOST_LIKELY:  35%  Generic SGR
DETECTORS:       0,0,1, 0,0,1, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       270.20d {+18h 00m 48s}  -23.44d {-23d 26' 14"}
SUN_DIST:         91.74 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      202.46d {+13h 29m 51s}  -14.83d {-14d 49' 53"}
MOON_DIST:       136.75 [deg]
MOON_ILLUM:      28 [%]
GAL_COORDS:      232.70,-87.44 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:        2.10,-31.64 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 116.23,-5.35 [deg].

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sun 21 Dec 08 16:21:52 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      73
TRIGGER_NUM:     251569273
GRB_RA:           18.383d {+01h 13m 32s} (J2000),
                  18.492d {+01h 13m 58s} (current),
                  17.778d {+01h 11m 07s} (1950)
GRB_DEC:         -21.917d {-21d 54' 59"} (J2000),
                 -21.869d {-21d 52' 08"} (current),
                 -22.181d {-22d 10' 52"} (1950)
GRB_ERROR:       4.08 [deg radius, statistical plus systematic]
GRB_INTEN:       1237 [cnts/sec]
DATA_SIGNIF:     86.50 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        14821 TJD;   356 DOY;   08/12/21
GRB_TIME:        58872.22 SOD {16:21:12.22} UT
GRB_PHI:          63.00 [deg]
GRB_THETA:        75.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      1.02
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      61%  GRB
2nd_MOST_LIKELY:  36%  Generic SGR
DETECTORS:       0,0,1, 0,0,1, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       270.20d {+18h 00m 48s}  -23.44d {-23d 26' 14"}
SUN_DIST:         96.84 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      202.46d {+13h 29m 51s}  -14.83d {-14d 49' 54"}
MOON_DIST:       143.09 [deg]
MOON_ILLUM:      28 [%]
GAL_COORDS:      168.07,-82.76 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:        7.76,-27.31 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 116.23,-5.35 [deg].

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sun 21 Dec 08 16:21:59 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      93
TRIGGER_NUM:     251569273
GRB_RA:           18.267d {+01h 13m 04s} (J2000),
                  18.375d {+01h 13m 30s} (current),
                  17.661d {+01h 10m 39s} (1950)
GRB_DEC:         -21.717d {-21d 42' 59"} (J2000),
                 -21.669d {-21d 40' 08"} (current),
                 -21.981d {-21d 58' 52"} (1950)
GRB_ERROR:       4.20 [deg radius, statistical plus systematic]
GRB_INTEN:       1092 [cnts/sec]
DATA_SIGNIF:     109.70 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        14821 TJD;   356 DOY;   08/12/21
GRB_TIME:        58872.22 SOD {16:21:12.22} UT
GRB_PHI:          63.00 [deg]
GRB_THETA:        75.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      1.10
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      61%  GRB
2nd_MOST_LIKELY:  36%  Generic SGR
DETECTORS:       0,0,1, 0,0,1, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       270.20d {+18h 00m 48s}  -23.44d {-23d 26' 14"}
SUN_DIST:         96.84 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      202.46d {+13h 29m 51s}  -14.83d {-14d 49' 56"}
MOON_DIST:       143.28 [deg]
MOON_ILLUM:      28 [%]
GAL_COORDS:      166.38,-82.69 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:        7.74,-27.09 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 116.23,-5.35 [deg].

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sun 21 Dec 08 16:21:50 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      70
TRIGGER_NUM:     251569273
GRB_RA:           18.783d {+01h 15m 08s} (J2000),
                  18.892d {+01h 15m 34s} (current),
                  18.180d {+01h 12m 43s} (1950)
GRB_DEC:         -22.600d {-22d 36' 00"} (J2000),
                 -22.553d {-22d 33' 09"} (current),
                 -22.864d {-22d 51' 50"} (1950)
GRB_ERROR:       5.50 [deg radius, statistical plus systematic]
GRB_INTEN:       580 [cnts/sec]
DATA_SIGNIF:     29.60 [sigma]
INTEG_TIME:      1.024 [sec]
GRB_DATE:        14821 TJD;   356 DOY;   08/12/21
GRB_TIME:        58872.22 SOD {16:21:12.22} UT
GRB_PHI:          63.00 [deg]
GRB_THETA:        75.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO:      1.39
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      61%  GRB
2nd_MOST_LIKELY:  35%  Generic SGR
DETECTORS:       0,0,1, 0,0,1, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       270.20d {+18h 00m 48s}  -23.44d {-23d 26' 14"}
SUN_DIST:         96.83 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      202.46d {+13h 29m 51s}  -14.83d {-14d 49' 54"}
MOON_DIST:       142.45 [deg]
MOON_ILLUM:      28 [%]
GAL_COORDS:      174.10,-82.97 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:        7.81,-28.09 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 116.23,-5.35 [deg].

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sun 21 Dec 08 16:22:39 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      58
TRIGGER_NUM:     251569273
GRB_RA:           10.160d {+00h 40m 38s} (J2000),
                  10.270d {+00h 41m 05s} (current),
                   9.546d {+00h 38m 11s} (1950)
GRB_DEC:         -28.780d {-28d 46' 47"} (J2000),
                 -28.731d {-28d 43' 50"} (current),
                 -29.054d {-29d 03' 14"} (1950)
GRB_ERROR:       3.34 [deg radius, statistical only]
DATA_SIGNIF:     19.80 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        14821 TJD;   356 DOY;   08/12/21
GRB_TIME:        58872.22 SOD {16:21:12.22} UT
GRB_PHI:          59.00 [deg]
GRB_THETA:        84.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   1 (Gnd S/W Version number)
SUN_POSTN:       270.20d {+18h 00m 48s}  -23.44d {-23d 26' 14"}
SUN_DIST:         87.10 [deg]   Sun_angle= -6.7 [hr] (East of Sun)
MOON_POSTN:      202.47d {+13h 29m 53s}  -14.83d {-14d 50' 04"}
MOON_DIST:       134.87 [deg]
MOON_ILLUM:      28 [%]
GAL_COORDS:      357.59,-87.10 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      356.71,-30.21 [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:     Sun 21 Dec 08 16:22:51 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      72
TRIGGER_NUM:     251569273
GRB_RA:           18.710d {+01h 14m 50s} (J2000),
                  18.818d {+01h 15m 16s} (current),
                  18.109d {+01h 12m 26s} (1950)
GRB_DEC:         -23.920d {-23d 55' 11"} (J2000),
                 -23.873d {-23d 52' 21"} (current),
                 -24.184d {-24d 11' 02"} (1950)
GRB_ERROR:       1.80 [deg radius, statistical only]
DATA_SIGNIF:     47.50 [sigma]
DATA_INTERVAL:   2.048 [sec]
GRB_DATE:        14821 TJD;   356 DOY;   08/12/21
GRB_TIME:        58872.22 SOD {16:21:12.22} UT
GRB_PHI:          64.00 [deg]
GRB_THETA:        76.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   1 (Gnd S/W Version number)
SUN_POSTN:       270.20d {+18h 00m 48s}  -23.44d {-23d 26' 14"}
SUN_DIST:         96.13 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      202.47d {+13h 29m 53s}  -14.84d {-14d 50' 06"}
MOON_DIST:       141.13 [deg]
MOON_ILLUM:      28 [%]
GAL_COORDS:      182.93,-83.82 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:        7.09,-29.25 [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:     Sun 21 Dec 08 16:22:54 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      75
TRIGGER_NUM:     251569273
GRB_RA:           14.300d {+00h 57m 12s} (J2000),
                  14.409d {+00h 57m 38s} (current),
                  13.691d {+00h 54m 46s} (1950)
GRB_DEC:         -25.160d {-25d 09' 35"} (J2000),
                 -25.112d {-25d 06' 41"} (current),
                 -25.430d {-25d 25' 48"} (1950)
GRB_ERROR:       1.91 [deg radius, statistical only]
DATA_SIGNIF:     130.10 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        14821 TJD;   356 DOY;   08/12/21
GRB_TIME:        58872.22 SOD {16:21:12.22} UT
GRB_PHI:          63.00 [deg]
GRB_THETA:        80.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   1 (Gnd S/W Version number)
SUN_POSTN:       270.20d {+18h 00m 48s}  -23.44d {-23d 26' 14"}
SUN_DIST:         92.01 [deg]   Sun_angle= -6.9 [hr] (East of Sun)
MOON_POSTN:      202.47d {+13h 29m 53s}  -14.84d {-14d 50' 07"}
MOON_DIST:       139.29 [deg]
MOON_ILLUM:      28 [%]
GAL_COORDS:      156.56,-87.64 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:        2.35,-28.62 [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:     Sun 21 Dec 08 16:22:47 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      69
TRIGGER_NUM:     251569273
GRB_RA:           11.680d {+00h 46m 43s} (J2000),
                  11.790d {+00h 47m 10s} (current),
                  11.068d {+00h 44m 16s} (1950)
GRB_DEC:         -27.100d {-27d 06' 00"} (J2000),
                 -27.051d {-27d 03' 03"} (current),
                 -27.373d {-27d 22' 22"} (1950)
GRB_ERROR:       4.27 [deg radius, statistical only]
DATA_SIGNIF:     24.20 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        14821 TJD;   356 DOY;   08/12/21
GRB_TIME:        58872.22 SOD {16:21:12.22} UT
GRB_PHI:          59.00 [deg]
GRB_THETA:        82.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   1 (Gnd S/W Version number)
SUN_POSTN:       270.20d {+18h 00m 48s}  -23.44d {-23d 26' 14"}
SUN_DIST:         89.04 [deg]   Sun_angle= -6.8 [hr] (East of Sun)
MOON_POSTN:      202.47d {+13h 29m 53s}  -14.84d {-14d 50' 05"}
MOON_DIST:       136.85 [deg]
MOON_ILLUM:      28 [%]
GAL_COORDS:       34.20,-88.95 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      358.96,-29.32 [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:     Sun 21 Dec 08 16:23:15 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     337889,   Seg_Num: 0
GRB_RA:           15.7934d {+01h 03m 10.4s} (J2000),
                  15.9021d {+01h 03m 36.5s} (current),
                  15.1871d {+01h 00m 44.8s} (1950)
GRB_DEC:         -24.5484d {-24d 32' 54.2"} (J2000),
                 -24.5003d {-24d 30' 01.2"} (current),
                 -24.8167d {-24d 49' 00.0"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       79 [cnts]
IMG_START_DATE:  14821 TJD;   356 DOY;   08/12/21
IMG_START_TIME:  58940.24 SOD {16:22:20.24} UT,   68.4 [sec] since BAT Trigger Time
CENTROID_X:      295.47,  raw= 295  [pixels]
CENTROID_Y:      318.84,  raw= 319  [pixels]
ROLL:            242.27 [deg]
GAIN:            2
MODE:            2, Short Image mode
WAVEFORM:        134
EXPO_TIME:       0.10 [sec]
GRB_POS_XRT_Y:   49.14
GRB_POS_XRT_Z:   -16.08
IMAGE_URL:       sw00337889000msxps_rw.img
SUN_POSTN:       270.20d {+18h 00m 48s}  -23.44d {-23d 26' 14"}
SUN_DIST:         93.50 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      202.47d {+13h 29m 54s}  -14.84d {-14d 50' 11"}
MOON_DIST:       140.14 [deg]
MOON_ILLUM:      28 [%]
GAL_COORDS:      169.25,-86.31 [deg] galactic lon,lat of the burst
ECL_COORDS:        4.04,-28.66 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 21 Dec 08 16:23:07 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     337889,   Seg_Num: 0
GRB_RA:           15.7934d {+01h 03m 10.4s} (J2000),
                  15.9021d {+01h 03m 36.5s} (current),
                  15.1871d {+01h 00m 44.8s} (1950)
GRB_DEC:         -24.5484d {-24d 32' 54.2"} (J2000),
                 -24.5003d {-24d 30' 01.2"} (current),
                 -24.8167d {-24d 49' 00.0"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       79 [cnts]
IMG_START_DATE:  14821 TJD;   356 DOY;   08/12/21
IMG_START_TIME:  58940.24 SOD {16:22:20.24} UT,   68.4 [sec] since BAT Trigger Time
CENTROID_X:      295.47,  raw= 295  [pixels]
CENTROID_Y:      318.84,  raw= 319  [pixels]
ROLL:            242.27 [deg]
GAIN:            2
MODE:            2, Short Image mode
WAVEFORM:        134
EXPO_TIME:       0.10 [sec]
GRB_POS_XRT_Y:   49.14
GRB_POS_XRT_Z:   -16.08
IMAGE_URL:       sw00337889000msxps_rw.img
SUN_POSTN:       270.20d {+18h 00m 48s}  -23.44d {-23d 26' 14"}
SUN_DIST:         93.50 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      202.47d {+13h 29m 54s}  -14.84d {-14d 50' 09"}
MOON_DIST:       140.14 [deg]
MOON_ILLUM:      28 [%]
GAL_COORDS:      169.25,-86.31 [deg] galactic lon,lat of the burst
ECL_COORDS:        4.04,-28.66 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 21 Dec 08 16:22:57 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     337889,   Seg_Num: 0
GRB_RA:           15.7934d {+01h 03m 10.41s} (J2000),
                  15.9021d {+01h 03m 36.51s} (current),
                  15.1871d {+01h 00m 44.89s} (1950)
GRB_DEC:         -24.5484d {-24d 32' 54.2"} (J2000),
                 -24.5003d {-24d 30' 01.2"} (current),
                 -24.8167d {-24d 49' 00.0"} (1950)
GRB_ERROR:       5.0 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       7.36e-08 [erg/cm2/sec]
GRB_SIGNIF:      8.88 [sigma]
IMG_START_DATE:  14821 TJD;   356 DOY;   08/12/21
IMG_START_TIME:  58940.24 SOD {16:22:20.24} UT,   68.4 [sec] since BAT Trigger Time
TAM[0-3]:        327.65 237.25 261.43 243.41
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       270.20d {+18h 00m 48s}  -23.44d {-23d 26' 14"}
SUN_DIST:         93.50 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      202.47d {+13h 29m 53s}  -14.84d {-14d 50' 07"}
MOON_DIST:       140.14 [deg]
MOON_ILLUM:      28 [%]
GAL_COORDS:      169.25,-86.31 [deg] galactic lon,lat of the burst
ECL_COORDS:        4.04,-28.66 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 1.49 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:     Sun 21 Dec 08 16:24:56 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     337889,   Seg_Num: 0
GRB_RA:           15.805d {+01h 03m 13s} (J2000),
                  15.914d {+01h 03m 39s} (current),
                  15.199d {+01h 00m 48s} (1950)
GRB_DEC:         -24.526d {-24d 31' 32"} (J2000),
                 -24.478d {-24d 28' 39"} (current),
                 -24.794d {-24d 47' 38"} (1950)
GRB_DATE:        14821 TJD;   356 DOY;   08/12/21
GRB_TIME:        58871.84 SOD {16:21:11.84} UT
TRIGGER_INDEX:   124
GRB_PHI:          37.50 [deg]
GRB_THETA:        27.14 [deg]
DELTA_TIME:      0.00 [sec]
TRIGGER_DUR:     0.512 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     12.84 [sigma]
IMAGE_SIGNIF:    8.37 [sigma]
LC_URL:          sw00337889000msb.lc
SUN_POSTN:       270.20d {+18h 00m 49s}  -23.44d {-23d 26' 14"}
SUN_DIST:         93.52 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      202.49d {+13h 29m 57s}  -14.84d {-14d 50' 31"}
MOON_DIST:       140.16 [deg]
MOON_ILLUM:      28 [%]
GAL_COORDS:      169.12,-86.29 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:        4.07,-28.65 [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 = 62.16,17.61 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 21 Dec 08 16:25:21 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     337889,   Seg_Num: 0
POINT_RA:         15.791d {+01h 03m 10s} (J2000)
POINT_DEC:       -24.531d {-24d 31' 51"} (J2000)
POINT_ROLL:      242.268d
IMG_START_DATE:  14821 TJD;   356 DOY;   08/12/21
IMG_START_TIME:  58949.90 SOD {16:22:29.90} UT,   78.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.261
N_STARS:         16
X_OFFSET:        384 [pixels]
Y_OFFSET:        616 [pixels]
X_MAX:           1343 [pixels]
Y_MAX:           1575 [pixels]
DET_THRESH:      12
PHOTO_THRESH:    6
SL_URL:          sw00337889000msufc0078.fits
SUN_POSTN:       270.20d {+18h 00m 49s}  -23.44d {-23d 26' 14"}
SUN_DIST:         93.50 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      202.49d {+13h 29m 58s}  -14.84d {-14d 50' 36"}
MOON_DIST:       140.15 [deg]
MOON_ILLUM:      28 [%]
GAL_COORDS:      169.04,-86.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:        4.05,-28.65 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 21 Dec 08 16:26:01 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     337889,   Seg_Num: 0
POINT_RA:         15.791d {+01h 03m 10s} (J2000)
POINT_DEC:       -24.531d {-24d 31' 51"} (J2000)
POINT_ROLL:      242.268d
IMG_START_DATE:  14821 TJD;   356 DOY;   08/12/21
IMG_START_TIME:  58949.90 SOD {16:22:29.90} UT,   78.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.261
N_STARS:         16
X_OFFSET:        384 [pixels]
Y_OFFSET:        616 [pixels]
X_MAX:           1343 [pixels]
Y_MAX:           1575 [pixels]
DET_THRESH:      12
PHOTO_THRESH:    6
SL_URL:          sw00337889000msufc0078.fits
SUN_POSTN:       270.20d {+18h 00m 49s}  -23.44d {-23d 26' 14"}
SUN_DIST:         93.50 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      202.50d {+13h 29m 59s}  -14.85d {-14d 50' 44"}
MOON_DIST:       140.15 [deg]
MOON_ILLUM:      28 [%]
GAL_COORDS:      169.04,-86.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:        4.05,-28.65 [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:     Sun 21 Dec 08 16:26:48 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     337889,   Seg_Num: 0
POINT_RA:         15.791d {+01h 03m 10s} (J2000)
POINT_DEC:       -24.531d {-24d 31' 51"} (J2000)
ROLL:            242.268d
IMG_START_DATE:  14821 TJD;   356 DOY;   08/12/21
IMG_START_TIME:  58949.90 SOD {16:22:29.90} UT,   78.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     251569353
X_OFFSET:        777 [pixels]
Y_OFFSET:        773 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       937
Y_GRB_POS:       933
BINNING_INDEX:   1
IM_URL:          sw00337889000msuni0078.fits
SUN_POSTN:       270.20d {+18h 00m 49s}  -23.44d {-23d 26' 14"}
SUN_DIST:         93.50 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      202.50d {+13h 30m 01s}  -14.85d {-14d 50' 53"}
MOON_DIST:       140.14 [deg]
MOON_ILLUM:      28 [%]
GAL_COORDS:      169.04,-86.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:        4.05,-28.65 [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:     Sun 21 Dec 08 16:27:18 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     337889,   Seg_Num: 0
POINT_RA:         15.791d {+01h 03m 10s} (J2000)
POINT_DEC:       -24.531d {-24d 31' 51"} (J2000)
ROLL:            242.268d
IMG_START_DATE:  14821 TJD;   356 DOY;   08/12/21
IMG_START_TIME:  58949.90 SOD {16:22:29.90} UT,   78.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     251569353
X_OFFSET:        777 [pixels]
Y_OFFSET:        773 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       937
Y_GRB_POS:       933
BINNING_INDEX:   1
IM_URL:          sw00337889000msuni0078.fits
SUN_POSTN:       270.20d {+18h 00m 49s}  -23.44d {-23d 26' 14"}
SUN_DIST:         93.50 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      202.51d {+13h 30m 02s}  -14.85d {-14d 51' 00"}
MOON_DIST:       140.14 [deg]
MOON_ILLUM:      28 [%]
GAL_COORDS:      169.04,-86.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:        4.05,-28.65 [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:        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:     Sun 21 Dec 08 16:32:01 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     337889,   Seg_Num: 0
POINT_RA:         15.791d {+01h 03m 10s} (J2000)
POINT_DEC:       -24.534d {-24d 32' 03"} (J2000)
POINT_ROLL:      242.267d
IMG_START_DATE:  14821 TJD;   356 DOY;   08/12/21
IMG_START_TIME:  59161.97 SOD {16:26:01.97} UT,   290.1 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.591
N_STARS:         8
X_OFFSET:        457 [pixels]
Y_OFFSET:        453 [pixels]
X_MAX:           1416 [pixels]
Y_MAX:           1412 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw00337889000msufc0290.fits
SUN_POSTN:       270.21d {+18h 00m 50s}  -23.44d {-23d 26' 14"}
SUN_DIST:         93.50 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      202.55d {+13h 30m 11s}  -14.87d {-14d 51' 56"}
MOON_DIST:       140.12 [deg]
MOON_ILLUM:      28 [%]
GAL_COORDS:      169.07,-86.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:        4.05,-28.65 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 21 Dec 08 16:32:29 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     337889,   Seg_Num: 0
POINT_RA:         15.791d {+01h 03m 10s} (J2000)
POINT_DEC:       -24.534d {-24d 32' 03"} (J2000)
POINT_ROLL:      242.267d
IMG_START_DATE:  14821 TJD;   356 DOY;   08/12/21
IMG_START_TIME:  59161.97 SOD {16:26:01.97} UT,   290.1 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.591
N_STARS:         8
X_OFFSET:        457 [pixels]
Y_OFFSET:        453 [pixels]
X_MAX:           1416 [pixels]
Y_MAX:           1412 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw00337889000msufc0290.fits
SUN_POSTN:       270.21d {+18h 00m 50s}  -23.44d {-23d 26' 14"}
SUN_DIST:         93.49 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      202.55d {+13h 30m 12s}  -14.87d {-14d 52' 01"}
MOON_DIST:       140.11 [deg]
MOON_ILLUM:      28 [%]
GAL_COORDS:      169.07,-86.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:        4.05,-28.65 [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:     Sun 21 Dec 08 16:33:18 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     337889,   Seg_Num: 0
POINT_RA:         15.791d {+01h 03m 10s} (J2000)
POINT_DEC:       -24.534d {-24d 32' 03"} (J2000)
ROLL:            242.267d
IMG_START_DATE:  14821 TJD;   356 DOY;   08/12/21
IMG_START_TIME:  59161.97 SOD {16:26:01.97} UT,   290.1 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     251569565
X_OFFSET:        777 [pixels]
Y_OFFSET:        773 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       937
Y_GRB_POS:       933
BINNING_INDEX:   1
IM_URL:          sw00337889000msuni0290.fits
SUN_POSTN:       270.21d {+18h 00m 50s}  -23.44d {-23d 26' 14"}
SUN_DIST:         93.49 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      202.56d {+13h 30m 14s}  -14.87d {-14d 52' 11"}
MOON_DIST:       140.11 [deg]
MOON_ILLUM:      28 [%]
GAL_COORDS:      169.07,-86.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:        4.05,-28.65 [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:     Sun 21 Dec 08 16:33:48 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     337889,   Seg_Num: 0
POINT_RA:         15.791d {+01h 03m 10s} (J2000)
POINT_DEC:       -24.534d {-24d 32' 03"} (J2000)
ROLL:            242.267d
IMG_START_DATE:  14821 TJD;   356 DOY;   08/12/21
IMG_START_TIME:  59161.97 SOD {16:26:01.97} UT,   290.1 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     251569565
X_OFFSET:        777 [pixels]
Y_OFFSET:        773 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       937
Y_GRB_POS:       933
BINNING_INDEX:   1
IM_URL:          sw00337889000msuni0290.fits
SUN_POSTN:       270.21d {+18h 00m 50s}  -23.44d {-23d 26' 14"}
SUN_DIST:         93.49 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      202.56d {+13h 30m 15s}  -14.87d {-14d 52' 17"}
MOON_DIST:       140.11 [deg]
MOON_ILLUM:      28 [%]
GAL_COORDS:      169.07,-86.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:        4.05,-28.65 [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:        If you have elected to receive attachments:  
COMMENTS:        The uvot_sources_image.fits.gz file does not exist; skipping the attachment.

GCN Circular #8687
E. A. Hoversten (PSU), W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU), M. M. Chester (PSU), J. R. Cummings (NASA/UMBC), J. A. Kennea (PSU), V. Mangano (INAF-IASFPA), C. B. Markwardt (CRESST/GSFC/UMD), F. E. Marshall (NASA/GSFC), P. T. O'Brien (U Leicester), D. M. Palmer (LANL), J. L. Racusin (PSU), P. Romano (INAF-IASFPA), B. A. Rowlinson (U Leicester), M. C. Stroh (PSU), G. Tagliaferri (INAF-OAB), T. N. Ukwatta (GSFC/GWU) and L. Vetere (PSU) report on behalf of the Swift Team:
At 16:21:11 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 081221 (trigger=337889). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 15.805, -24.526 which is
```
   RA(J2000) = 01h 03m 13s
   Dec(J2000) = -24d 31' 32"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed two peaks, at T+0 to T+10 seconds and a much larger one at T+15 to T+40 seconds. The peak count rate was ~20000 counts/sec (15-350 keV), at 22 sec after the trigger.
The XRT began observing the field at 16:22:20.2 UT, 68.4 seconds after the BAT trigger. XRT found a bright, fading, uncatalogued X-ray source located at RA, Dec 15.7934, -24.5484 which is equivalent to:
```
   RA(J2000)  = 01h 03m 10.41s
   Dec(J2000) = -24d 32' 54.2"
```
with an uncertainty of 5.0 arcseconds (radius, 90% containment). This location is 89 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 0.1 s image was 7.36e-08 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 78 seconds after the BAT trigger, and a finding chart exposure of 250 seconds with the u filter starting 290 seconds after the 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 3-sigma upper limit at the XRT position is 19.9 mag in White, 19.8 mag in u. No correction has been made for the expected extinction corresponding to E(B-V) of 0.02.
We note that this burst is coincident with a Fermi GBM burst (trigger 251569273).
Burst Advocate for this burst is E. A. Hoversten (hoversten AT astro.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 Circular #8688
Daniele Malesani, Johan P. U. Fynbo (DARK/NBI), Eric Stempels (Univ. St. Andrews), and Tapio Pursimo (NOT), report on behalf of a larger collaboration:
We observed the field of GRB 081221 (Hoversten et al., GCN 8687) with the NOT equipped with ALFOSC. R-band imaging was carried out (12 min exposure) with mean time Dec 21.81 UT (3.14 hr after the GRB). Inside the XRT error circle (Hoversten et al., GCN 8687), we detect no source down to a limiting magnitude R ~ 23. Further imaging is ongoing.
We note the presence of two faint sources just outside the XRT error circle, at approximate coordinates (J2000):
```
1: RA = 01:03:10.26, Dec = -24:32:47.4, R ~ 22.3
2: RA = 01:03:10.10, Dec = -24:32:58.6, R ~ 23.0
```
We acknowledge excellent support from the NOT staff.
GCN Circular #8689
Daniele Malesani, Johan P. U. Fynbo (DARK/NBI), Tapio Pursimo (NOT), and Eric Stempels (Univ. St. Andrews) report on behalf of a larger collaboration:
Further to what reported in GCN 8688, we observed the field of GRB 081221 (Hoversten et al., GCN 8687) in the I and z filters with the NOT equipped with ALFOSC. Exposure times were 18 and 16 min, respectively, with mean times Dec 21.844 and Dec 21.863 UT (3.89 and 4.37 hr after the GRB, respectively).
Inside the XRT error circle reported by Hoversten et al. (GCN 8687), we do not detect any source in either filters. The limiting magnitude is I ~ 23 assuming I = 17.65 for the USNO star at RA = 01:03:09.59, Dec = -24:32:45.0.
We encourage deeper searches of the optical/NIR counterpart of this event, which had a bright gamma- and X-ray prompt emission.
GCN Circular #8690
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team.
Using 4345 s of XRT Photon Counting mode data and 7 UVOT images for GRB 081221, 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 = 15.7925, -24.5481 which is equivalent to:
```
RA (J2000): 01h 03m 10.20s
Dec (J2000): -24d 32' 53.1"
```
with an uncertainty of 1.4 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 #8694
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 081221 (Hoversten et al., GCN 8687) triggered Konus-Wind at T0=58874.915 s UT (16:21:14.915).
The burst light curve shows two multipeaked pulses with a total duration of ~40 s.
As observed by Konus-Wind the burst had a fluence of (2.28 +/- 0.07)x10^-5 erg/cm2, and a 256-ms peak flux measured from T0+19.824 s of (1.75 +/- 0.16)x10^-6 erg/cm2/s (both in the 20 keV - 1 MeV energy range).
The time-integrated spectrum of the burst (from T0 to T0+39.424 s) can be fitted (in the 20 keV-1 MeV range) by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.91(-0.14, +0.15), and Ep = (83 +/- 4) keV (chi2 = 67.4/51 dof). Fitting by GRB (Band) model yields the same alpha and Ep, and only an upper limit on the high energy photon index: beta < -3.48 (chi2 = 67.4/50 dof).
Thus, it is a bright and soft GRB.
All the quoted errors are at the 90% confidence level.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB081221_T58874/
GCN Circular #8698
N. R. Tanvir (U. Leicester), A. J. Levan (U. Warwick), K. Wiersema (U. Leicester), A. S. Fruchter, J. Graham (STScI) report:
We observed the field of GRB 081221 with Gemini-N/NIRI, starting 22 Dec 2008 04:20UT, approximately 12 hours post burst.
Our preliminary analysis reveals a faint point source in the enhanced XRT error circle (GCN 8690) with magnitude K~20.1 at position:
```
01:03:10.19
-24:32:52.2
```
relative to three 2MASS stars in the field. The source is also marginally detected in J and H.
We suggest this is most likely the afterglow of GRB 081221, but that its faintness and red colour (H-K>~2) argue for a dusty sight-line rather than a high redshift as the explanation for the absence of an optical detection (GCN 8688 and GCN 8689).
Further analysis is ongoing.
We thank Ricardo Schiavon (Gemini) for his assistance in obtaining these observations.
GCN Circular #8700
A. Pelangeon and J-L. Atteia (LATT-OMP) report:
We have used the spectral parameters of GRB 081221 provided by Golenetskii et al. (GCN Circ. 8694) to compute the spectral pseudo-redshift** of this burst detected by Swift-BAT (Hoversten et al. GCNC 8687).
We find a pseudo-redshift pz = 0.7 +/- 0.1
** http://cosmos.ast.obs-mip.fr/projet/index.html
GCN Circular #8701
M.C. Stroh and E. A. Hoversten (PSU) report on behalf of the Swift-XRT team:
We have analyzed the first seven orbits of XRT data from GRB 081221 (Hoversten et al., GCN 8687) beginning 73s after the trigger. The Swift-XRT data consists of 803s in Windowed Timing (WT) mode and 5.9ks in Photon Counting (PC) mode. The enhanced XRT position for this burst was reported by Evans et al. (GCN Circ. 8690).
The X-ray light curve begins with count rates near 10^3 cts/s and has an early flare reaching 1130 cts/s at T+103s. Following the flare, the light curve can be modeled with a double broken power-law with initial decay rate of 5.48 +/- 0.08, initial break time at T+207s, second decay rate of 0.68 +/- 0.20, second break time at T+896s, and a final decay rate of 1.35 +/- 0.04. If the light curve follows the same decline, we predict count rates at T+24hr and T+48hr to be 1.6e-2 and 6.4e-3 respectively.
The time-averaged WT spectrum can be fit with an absorbed power law with photon index Gamma = 1.994 (+/-0.014) and nH of 3.24 (+/- 0.05) e21 cm^-2 which is in excess of the Galactic value of 2.03e20 cm^-2 (Kalberla et al. 2005). The absorbed (unabsorbed) 0.3-10.0 keV flux is 2.44 (3.86) e-9 ergs/cm^2/s.
The time-averaged PC spectrum can be fit with an absorbed power law with photon index Gamma = 2.37 (+/-0.15) and nH of 3.5 (+/-0.5) e21 cm^-2. The absorbed (unabsorbed) 0.3-10.0 keV flux is 1.04 (2.17) e-11 ergs/cm^2/s.
This circular is an official product of the Swift-XRT team.

GCN Circular #8703
N. P. M. Kuin (MSSL/UCL) and E. A. Hoversten (PSU) report on behalf of the Swift UVOT team.
The Swift UltraViolet/Optical Telescope (UVOT) began settled observations of GRB081221 (Swift BAT trigger number 337889, Hoversten et al., GCN Circ. 8687), on December 21, 2008, at 16:22:29, 78 seconds after the trigger with a white finding chart.
We do not detect any new source at the enhanced XRT position reported in GCN Circ. 8690 (Evans et al.).
The observed magnitude upper limits for GRB 081221 are given below for the first observations and the summed exposures in the UVOT filters:

Filter Tstart(s) Tstop(s)  Exp(s)  Magnitude

wh       78       228     149.8    >20.84  (3-sigma UL)
v       619       639      19.4    >17.89  (3-sigma UL)
b       545       565      19.4    >18.85  (3-sigma UL)
u       290       540     245.8    >20.15  (3-sigma UL)
uvw1    668       688      19.4    >18.10  (3-sigma UL)
uvm2    644       664      19.5    >17.71  (3-sigma UL)
uvw2    595       615      19.4    >18.08  (3-sigma UL)

wh       78      6086     381.0    >21.41  (3-sigma UL)
v        59     34696    2192.4    >20.74  (3-sigma UL)
b       545     41269    1765.2    >21.55  (3-sigma UL)
u       290     40478    3667.7    >21.69  (3-sigma UL)
uvw1    668     39565    3758.4    >21.57  (3-sigma UL)
uvm2    644     45178    3409.4    >21.55  (3-sigma UL)
uvw2    595     33783    2005.6    >21.35  (3-sigma UL)

The values quoted above are on the UVOT Photometric System (Poole et al, 2008, MNRAS 383,627). They are not corrected for the expected galactic reddening of E(B-V) = 0.021 in the direction of the burst (Schlegel et al. 1998).

GCN Circular #8704
Colleen A. Wilson-Hodge (NASA/MSFC) reports on behalf of the Fermi GBM Team:
"At 16:21:12.22 UT on 21 December 2008, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 081221 (trigger 251569273 / 081221681), which was also detected by the SWIFT-BAT and XRT (Hoversten et al. 2008, GCN 8687).
The on-ground calculated location, using the GBM trigger data, is RA = 17.2, DEC = -24.8 (J2000 degrees, equivalent to 01 h 09 m, -24 d 50'), with an uncertainty of less than 1.0 degree (radius, 1-sigma containment, statistical only; there is additionally a systematic error which is currently estimated to be 2 to 3 degrees).
The angle from the Fermi LAT boresight is 78 degrees.
The GBM light curve consists of a weak initial peak and a bright second peak with a duration (T90) of about 40 s (8-1000 keV). The time-averaged spectrum from T0+0.003 s to T0+38.401 s is adequately fit by a Band function with Epeak = 77 +/- 1 keV, alpha = -0.42 +/- 0.03, and beta = -2.91 +/- 0.08. These spectral parameters are consistent with Konus-Wind observations (Golenetskii et al. 2008, GCN 8694.)
The event fluence (8-1000 keV) in this time interval is (3.7 +/- 0.1)E-05 erg/cm^2. The 64-msec peak photon flux measured starting from T0+19.3923 s in the 8-1000 keV band is 33 +/- 9 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN Circular #8708
J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), E. A. Hoversten (PSU), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), K. McLean (GSFC/UMD), D. M. Palmer (LANL), A. M. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), 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-239 to T+873 sec from the recent telemetry downlink, we report further analysis of BAT GRB 081221 (trigger #337889) (Hoversten, et al., GCN Circ. 8687). The BAT ground-calculated position is RA, Dec = 15.801, -24.542 deg which is
```
  RA(J2000)  =  01h 03m 12.2s
  Dec(J2000) = -24d 32' 32.8"
```
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 61%.
The mask-weighted light curve shows two main overlapping peaks, the smaller from about T+0 to T+12 sec and the larger from about T+12 to T+40 sec, with multiple subsidiary peaks and an extended tail visible to about T+150 sec. T90 (15-350 keV) is 34 +- 1 sec (estimated error including systematics).
The time-averaged spectrum from T-0.3 to T+112.6 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 1.21 +- 0.13, and Epeak of 69.9 +- 3.9 keV (chi squared 37.73 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 1.81 +- 0.03 x 10-05 erg/cm2 and the 1-sec peak flux measured from T+21.42 sec in the 15-150 keV band is 18.2 +- 0.5 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.86 (chi squared 119.90 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/337889/BA/
GCN Circular #8711
D. A. Perley, J. S. Bloom (UC Berkeley), J. Kalirai (STSCI), R. Strickler, E. Ramirez-Ruiz (UCSC), and A. A. Miller (UCB) report:
We began a series of deep optical imaging exposures on the field of GRB 081221 (Hoversten et al., GCN 8687) using the Keck I telescope (+LRIS) starting at 2008-12-23 at 5:06 UT. We acquired 10x330s in g-band and 10x300s in I-band (simultaneously using the 560 dichroic).
A extended source coincident with the Gemini (Tanvir et al., GCN 8698) and Swift XRT (GCN 8690) afterglow positions is clearly detected in our g-band stack, which we tentatively identify as the host galaxy. The magnitude within a 1.0" aperture of this object is approximately B~25.4 (calibrated relative to the USNO star at RA=15.797098, dec=-24.412259, B2=19.59). It is only marginally detected in the I-band imaging, with an estimated magnitude of I~24.5, though photometry in this band is complicated by blending with a nearby object.
The detection of a host galaxy would be consistent with a low-redshift origin (GCN 8698). Within the significant uncertainties of the photometric calibration the color of the galaxy appears typical of normal GRB hosts. Further analysis is planned.
An image of the field is posted to: http://lyra.berkeley.edu/~dperley/081221/081221hostkeck.png
GCN Circular #8719
GRB 081221: GROND observations
P. Afonso, T. Kruehler, J. Greiner, C. Clemens (all MPE Garching) and A. Updike (Clemson University) report on behalf of the GROND team:
GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2m ESO/MPI telescope at La Silla Observatory (Chile) imaged the field of GRB 081221 (Swift trigger 337889, Hoversten et al., GCN #8687) on two epochs simultaneously in g'r'i'z'JHK. This burst was also detected by Konus-Wind (Golenetskii et al. GCN #8694) and the Fermi GBM (Wilson-Hodge, GCN #8704).
The first epoch started on 2008-12-22 at 01:33:08 UT roughly 9 hours after the trigger and consisted of 16 images of 375s exposure in g'r'i'z' and 480 images of 10s exposure in JHK. An equal amount of images were obtained during the second epoch in the following night from 01:19:56 UT on, 33 hours after the burst.
Inside the refined XRT error circle (Stroh & Hoversten, GCN #8701) we detect in both epochs the object reported by Tanvir et al.(GCN #8698) and Perley et al. (GCN #8711) in g'r'i', but not in z'JHK.
No variability between the two epochs is evident, and no other source is detected inside the XRT error circle.
Preliminary VEGA magnitudes from the second epoch calibrated against USNO-B field stars and upper limits are as follows:
```
g' = 25.2 +/- 0.3
r' = 24.7 +/- 0.2
i' = 24.4 +/- 0.4
z' > 24.0
J > 21.0
H > 19.8
K > 19.0 
```
Given the large errors due to image statistics, photometric calibration and complicated photometry as pointed out by Perley et al. (GCN #8711), these values are consistent with what is reported in GCNs #8698 and #8711.
GCN Circular #8741
Poonam Chandra (RMC) and Dale A. Frail (NRAO) report on behalf of the Caltech-NRAO-Carnegie GRB Collaboration:
"We used the Very Large Array to observe the field of view toward GRB 081221 (GCN 8687) at a frequency of 8.46 GHz on 2008 Dec 27.14 UT. The GRB radio afterglow is undetected at 3-sigma level. However, there is a 2.5 sigma source (97 +/- 38 uJy) at the Gemini optical afterglow position reported by Tanvir et al. (GCN 8698).
The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc."
GCN Circular #8748
Poonam Chandra (RMC) and Dale A. Frail (NRAO) report on behalf of the Caltech-NRAO-Carnegie GRB Collaboration:
"We used the Very Large Array to re-observe the field of view toward GRB 081221 (GCN 8687) at a frequency of 8.46 GHz on 2008 Dec 28.16 UT for a longer integration. The GRB radio afterglow is clearly detected at the Gemini optical afterglow position (GCN 8698) with the flux density of 167 +/- 27 uJy.
The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc."
New/revised redshift: Salvaterra et al. 2012, ApJ 749, 68
1302.6091 from 26 Feb 13
Rupal Basak et al.: A new method of pulse-wise spectral analysis of Gamma-ray Bursts
Time-resolved spectral analysis, though a very promising method to understand the emission mechanism of gamma-ray bursts (GRBs), is difficult to implement in practice because of poor statistics. We present a new method for pulse-wise time-resolved spectral study of the individual pulses of GRBs, using the fact that many spectral parameters are either constants or smooth functions of time. We use this method for the two pulses of GRB 081221, the brightest GRB with separable pulses. We choose, from the literature, a set of possible models which includes the Band model, blackbody with a power-law (BBPL), a collection of black bodies with a smoothly varying temperature profile, along with a power-law (mBBPL), and two blackbodies with a power-law (2BBPL). First, we perform time-resolved study to confirm the spectral parameter variations, and then construct the new model to perform a joint spectral fit. We find that any photospheric emission in terms of black bodies is required mainly in the rising parts of the pulses and the falling part can be adequately explained in terms of the Band model, with the low energy photon index within the regime of synchrotron model. Interestingly, we find that 2BBPL is comparable or sometimes even better, though marginally, than the Band model, in all episodes. Consistent results are also obtained for the brightest GRB of Fermi era --- GRB 090618. We point out that the method is generic enough to test any spectral model with well defined parameter variations.

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Jochen Greiner, last update: 26-Feb-2013 [Disclaimer]