Gamma-ray Burst 111228A

(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:     Wed 28 Dec 11 15:45:32 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     510649,   Seg_Num: 0
GRB_RA:          150.079d {+10h 00m 19s} (J2000),
                 150.244d {+10h 00m 58s} (current),
                 149.392d {+09h 57m 34s} (1950)
GRB_DEC:         +18.293d {+18d 17' 35"} (J2000),
                 +18.235d {+18d 14' 06"} (current),
                 +18.533d {+18d 32' 00"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       15872 [cnts]    Image_Peak=494 [image_cnts]
TRIGGER_DUR:     4.096 [sec] 
TRIGGER_INDEX:   292     E_range: 15-50 keV
BKG_INTEN:       136829 [cnts]
BKG_TIME:        56624.27 SOD {15:43:44.27} UT
BKG_DUR:         40 [sec]
GRB_DATE:        15923 TJD;   362 DOY;   11/12/28
GRB_TIME:        56683.60 SOD {15:44:43.60} UT
GRB_PHI:          12.98 [deg]
GRB_THETA:        41.32 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     16.82 [sigma]
IMAGE_SIGNIF:    11.28 [sigma]
MERIT_PARAMS:     +1  +0  +0  +2  +1  +1  +0  +0 +65  +0 
SUN_POSTN:       277.13d {+18h 28m 31s}  -23.28d {-23d 16' 30"}
SUN_DIST:        130.34 [deg]   Sun_angle= 8.5 [hr] (West of Sun)
MOON_POSTN:      326.34d {+21h 45m 21s}   -8.24d {-08d 14' 13"}
MOON_DIST:       169.30 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      216.34, 49.76 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      145.79,  5.72 [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 = 177.55,-1.88 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Wed 28 Dec 11 15:46:07 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      57
TRIGGER_NUM:     346779932
GRB_RA:          148.450d {+09h 53m 48s} (J2000),
                 148.618d {+09h 54m 28s} (current),
                 147.749d {+09h 51m 00s} (1950)
GRB_DEC:         +22.233d {+22d 13' 60"} (J2000),
                 +22.176d {+22d 10' 35"} (current),
                 +22.470d {+22d 28' 11"} (1950)
GRB_ERROR:       6.73 [deg radius, statistical plus systematic]
GRB_INTEN:       356 [cnts/sec]
DATA_SIGNIF:     26.20 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        15923 TJD;   362 DOY;   11/12/28
GRB_TIME:        56730.80 SOD {15:45:30.80} UT
GRB_PHI:         227.00 [deg]
GRB_THETA:        65.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      2.11
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      76%  GRB
2nd_MOST_LIKELY:  23%  Generic SGR
DETECTORS:       0,0,0, 0,0,0, 0,1,1, 0,0,1, 0,0,
SUN_POSTN:       277.13d {+18h 28m 31s}  -23.28d {-23d 16' 30"}
SUN_DIST:        132.75 [deg]   Sun_angle= 8.6 [hr] (West of Sun)
MOON_POSTN:      326.34d {+21h 45m 22s}   -8.24d {-08d 14' 07"}
MOON_DIST:       165.89 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      209.82, 49.56 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      142.98,  8.89 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 69.35,3.85 [deg].  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(47.0<100sec) coincident with the SWIFT_BAT event (trignum=510649).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Wed 28 Dec 11 15:45:59 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      44
TRIGGER_NUM:     346779932
GRB_RA:          160.100d {+10h 40m 24s} (J2000),
                 160.256d {+10h 41m 01s} (current),
                 159.450d {+10h 37m 48s} (1950)
GRB_DEC:          +5.433d {+05d 25' 60"} (J2000),
                  +5.371d {+05d 22' 14"} (current),
                  +5.695d {+05d 41' 40"} (1950)
GRB_ERROR:       10.55 [deg radius, statistical plus systematic]
GRB_INTEN:       248 [cnts/sec]
DATA_SIGNIF:     10.40 [sigma]
INTEG_TIME:      1.024 [sec]
GRB_DATE:        15923 TJD;   362 DOY;   11/12/28
GRB_TIME:        56730.80 SOD {15:45:30.80} UT
GRB_PHI:         223.00 [deg]
GRB_THETA:        85.00 [deg]
DATA_TIME_SCALE: 1.0240 [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, 0,1,1, 0,0,1, 0,0,
SUN_POSTN:       277.13d {+18h 28m 31s}  -23.28d {-23d 16' 30"}
SUN_DIST:        116.77 [deg]   Sun_angle= 7.8 [hr] (West of Sun)
MOON_POSTN:      326.34d {+21h 45m 21s}   -8.24d {-08d 14' 08"}
MOON_DIST:       165.89 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      241.84, 52.02 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      159.58, -2.75 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 69.35,3.85 [deg].  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(47.0<100sec) coincident with the SWIFT_BAT event (trignum=510649).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 28 Dec 11 15:47:39 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     510649,   Seg_Num: 0
GRB_RA:          150.0643d {+10h 00m 15.43s} (J2000),
                 150.2289d {+10h 00m 54.93s} (current),
                 149.3770d {+09h 57m 30.48s} (1950)
GRB_DEC:         +18.2996d {+18d 17' 58.5"} (J2000),
                 +18.2417d {+18d 14' 30.1"} (current),
                 +18.5400d {+18d 32' 24.0"} (1950)
GRB_ERROR:       7.0 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       8.82e-09 [erg/cm2/sec]
GRB_SIGNIF:      4.47 [sigma]
IMG_START_DATE:  15923 TJD;   362 DOY;   11/12/28
IMG_START_TIME:  56828.67 SOD {15:47:08.67} UT,   145.1 [sec] since BAT Trigger Time
TAM[0-3]:        327.66 237.23 261.43 243.74
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       277.13d {+18h 28m 32s}  -23.28d {-23d 16' 30"}
SUN_DIST:        130.36 [deg]   Sun_angle= 8.5 [hr] (West of Sun)
MOON_POSTN:      326.35d {+21h 45m 25s}   -8.23d {-08d 13' 49"}
MOON_DIST:       169.30 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      216.32, 49.75 [deg] galactic lon,lat of the burst
ECL_COORDS:      145.78,  5.72 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 0.93 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 28 Dec 11 15:47:56 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     510649,   Seg_Num: 0
GRB_RA:          150.0643d {+10h 00m 15.4s} (J2000),
                 150.2289d {+10h 00m 54.9s} (current),
                 149.3770d {+09h 57m 30.4s} (1950)
GRB_DEC:         +18.2996d {+18d 17' 58.5"} (J2000),
                 +18.2417d {+18d 14' 30.1"} (current),
                 +18.5400d {+18d 32' 24.0"} (1950)
GRB_ERROR:       6.8 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       20 [cnts]
IMG_START_DATE:  15923 TJD;   362 DOY;   11/12/28
IMG_START_TIME:  56828.67 SOD {15:47:08.67} UT,   145.1 [sec] since BAT Trigger Time
CENTROID_X:      249.68,  raw= 250  [pixels]
CENTROID_Y:      314.53,  raw= 315  [pixels]
ROLL:            105.32 [deg]
GAIN:            1
MODE:            2, Short Image mode
WAVEFORM:        134
EXPO_TIME:       0.10 [sec]
GRB_POS_XRT_Y:   38.96
GRB_POS_XRT_Z:   -127.32
IMAGE_URL:       sw00510649000msxps_rw.img
SUN_POSTN:       277.13d {+18h 28m 32s}  -23.28d {-23d 16' 30"}
SUN_DIST:        130.36 [deg]   Sun_angle= 8.5 [hr] (West of Sun)
MOON_POSTN:      326.36d {+21h 45m 25s}   -8.23d {-08d 13' 46"}
MOON_DIST:       169.30 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      216.32, 49.75 [deg] galactic lon,lat of the burst
ECL_COORDS:      145.78,  5.72 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 28 Dec 11 15:47:50 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     510649,   Seg_Num: 0
GRB_RA:          150.0643d {+10h 00m 15.4s} (J2000),
                 150.2289d {+10h 00m 54.9s} (current),
                 149.3770d {+09h 57m 30.4s} (1950)
GRB_DEC:         +18.2996d {+18d 17' 58.5"} (J2000),
                 +18.2417d {+18d 14' 30.1"} (current),
                 +18.5400d {+18d 32' 24.0"} (1950)
GRB_ERROR:       6.8 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       20 [cnts]
IMG_START_DATE:  15923 TJD;   362 DOY;   11/12/28
IMG_START_TIME:  56828.67 SOD {15:47:08.67} UT,   145.1 [sec] since BAT Trigger Time
CENTROID_X:      249.68,  raw= 250  [pixels]
CENTROID_Y:      314.53,  raw= 315  [pixels]
ROLL:            105.32 [deg]
GAIN:            1
MODE:            2, Short Image mode
WAVEFORM:        134
EXPO_TIME:       0.10 [sec]
GRB_POS_XRT_Y:   38.96
GRB_POS_XRT_Z:   -127.32
IMAGE_URL:       sw00510649000msxps_rw.img
SUN_POSTN:       277.13d {+18h 28m 32s}  -23.28d {-23d 16' 30"}
SUN_DIST:        130.36 [deg]   Sun_angle= 8.5 [hr] (West of Sun)
MOON_POSTN:      326.35d {+21h 45m 25s}   -8.23d {-08d 13' 47"}
MOON_DIST:       169.30 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      216.32, 49.75 [deg] galactic lon,lat of the burst
ECL_COORDS:      145.78,  5.72 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 28 Dec 11 15:48:46 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     510649,   Seg_Num: 0
GRB_RA:          150.079d {+10h 00m 19s} (J2000),
                 150.244d {+10h 00m 58s} (current),
                 149.392d {+09h 57m 34s} (1950)
GRB_DEC:         +18.293d {+18d 17' 35"} (J2000),
                 +18.235d {+18d 14' 06"} (current),
                 +18.533d {+18d 32' 00"} (1950)
GRB_DATE:        15923 TJD;   362 DOY;   11/12/28
GRB_TIME:        56683.60 SOD {15:44:43.60} UT
TRIGGER_INDEX:   292
GRB_PHI:          12.98 [deg]
GRB_THETA:        41.32 [deg]
DELTA_TIME:      -11.00 [sec]
TRIGGER_DUR:     4.096 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     16.82 [sigma]
IMAGE_SIGNIF:    11.28 [sigma]
LC_URL:          sw00510649000msb.lc
SUN_POSTN:       277.13d {+18h 28m 32s}  -23.28d {-23d 16' 30"}
SUN_DIST:        130.34 [deg]   Sun_angle= 8.5 [hr] (West of Sun)
MOON_POSTN:      326.36d {+21h 45m 27s}   -8.23d {-08d 13' 36"}
MOON_DIST:       169.30 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      216.34, 49.76 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      145.79,  5.72 [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 = 177.55,-1.88 [deg].

GCN NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Wed 28 Dec 11 15:46:20 UT
NOTICE_TYPE:    INTEGRAL SPI ACS Trigger
TRIGGER_NUM:    6423,   Sub_Num: 0
GRB_INTEN:      10.28 [sigma]  
GRB_TIME:       56734.35 SOD {15:45:34.35} UT
GRB_DATE:       15923 TJD;   362 DOY;   11/12/28
COMMENTS:       INTEGRAL SPI_ACS GRB Trigger.
COMMENTS:
COMMENTS:       NOTE: This SPIACS event is temporally(4.0<100sec) coincident with the FERMI_GBM event (trignum=346779932).
COMMENTS:
COMMENTS:       The SPIACS lightcurve can be found at: 
COMMENTS:       ftp://isdcarc.unige.ch/arc/FTP/ibas/spiacs/2011-12/2011-12-28T15-45-34.1202-01361-60304-0.lc

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Wed 28 Dec 11 15:49:47 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      68
TRIGGER_NUM:     346779932
GRB_RA:          147.500d {+09h 50m 00s} (J2000),
                 147.663d {+09h 50m 39s} (current),
                 146.818d {+09h 47m 16s} (1950)
GRB_DEC:         +15.380d {+15d 22' 48"} (J2000),
                 +15.324d {+15d 19' 25"} (current),
                 +15.614d {+15d 36' 50"} (1950)
GRB_ERROR:       2.33 [deg radius, statistical only]
DATA_SIGNIF:     28.10 [sigma]
DATA_INTERVAL:   2.048 [sec]
GRB_DATE:        15923 TJD;   362 DOY;   11/12/28
GRB_TIME:        56730.80 SOD {15:45:30.80} UT
GRB_PHI:         221.00 [deg]
GRB_THETA:        69.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4143 (Gnd S/W Version number)
SUN_POSTN:       277.13d {+18h 28m 32s}  -23.28d {-23d 16' 30"}
SUN_DIST:        131.88 [deg]   Sun_angle= 8.6 [hr] (West of Sun)
MOON_POSTN:      326.37d {+21h 45m 29s}   -8.22d {-08d 13' 24"}
MOON_DIST:       172.79 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      219.00, 46.38 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      144.46,  2.14 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(4.0<100sec) coincident with the INTEGRAL_SPIACS event (trignum=6423).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 28 Dec 11 15:50:05 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     510649,   Seg_Num: 0
POINT_RA:        150.026d {+10h 00m 06s} (J2000)
POINT_DEC:       +18.297d {+18d 17' 50"} (J2000)
POINT_ROLL:      105.318d
IMG_START_DATE:  15923 TJD;   362 DOY;   11/12/28
IMG_START_TIME:  56838.97 SOD {15:47:18.97} UT,   155.4 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.710
N_STARS:         13
X_OFFSET:        662 [pixels]
Y_OFFSET:        363 [pixels]
X_MAX:           1621 [pixels]
Y_MAX:           1322 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    7
SL_URL:          sw00510649000msufc0155.fits
SUN_POSTN:       277.13d {+18h 28m 32s}  -23.28d {-23d 16' 30"}
SUN_DIST:        130.39 [deg]   Sun_angle= 8.5 [hr] (West of Sun)
MOON_POSTN:      326.37d {+21h 45m 30s}   -8.22d {-08d 13' 21"}
MOON_DIST:       169.32 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      216.31, 49.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      145.75,  5.70 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 28 Dec 11 15:50:29 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     510649,   Seg_Num: 0
POINT_RA:        150.026d {+10h 00m 06s} (J2000)
POINT_DEC:       +18.297d {+18d 17' 50"} (J2000)
POINT_ROLL:      105.318d
IMG_START_DATE:  15923 TJD;   362 DOY;   11/12/28
IMG_START_TIME:  56838.97 SOD {15:47:18.97} UT,   155.4 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.710
N_STARS:         13
X_OFFSET:        662 [pixels]
Y_OFFSET:        363 [pixels]
X_MAX:           1621 [pixels]
Y_MAX:           1322 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    7
SL_URL:          sw00510649000msufc0155.fits
SUN_POSTN:       277.13d {+18h 28m 32s}  -23.28d {-23d 16' 30"}
SUN_DIST:        130.39 [deg]   Sun_angle= 8.5 [hr] (West of Sun)
MOON_POSTN:      326.38d {+21h 45m 31s}   -8.22d {-08d 13' 16"}
MOON_DIST:       169.32 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      216.31, 49.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      145.75,  5.70 [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:     Wed 28 Dec 11 15:52:39 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     510649,   Seg_Num: 0
POINT_RA:        150.026d {+10h 00m 06s} (J2000)
POINT_DEC:       +18.297d {+18d 17' 50"} (J2000)
ROLL:            105.318d
IMG_START_DATE:  15923 TJD;   362 DOY;   11/12/28
IMG_START_TIME:  56838.97 SOD {15:47:18.97} UT,   155.4 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     346780046
X_OFFSET:        982 [pixels]
Y_OFFSET:        683 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1142
Y_GRB_POS:       843
BINNING_INDEX:   1
IM_URL:          sw00510649000msuni0163.fits
SUN_POSTN:       277.14d {+18h 28m 32s}  -23.28d {-23d 16' 29"}
SUN_DIST:        130.40 [deg]   Sun_angle= 8.5 [hr] (West of Sun)
MOON_POSTN:      326.40d {+21h 45m 35s}   -8.21d {-08d 12' 51"}
MOON_DIST:       169.32 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      216.31, 49.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      145.75,  5.70 [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:     Wed 28 Dec 11 15:52:58 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     510649,   Seg_Num: 0
POINT_RA:        150.026d {+10h 00m 06s} (J2000)
POINT_DEC:       +18.297d {+18d 17' 50"} (J2000)
ROLL:            105.318d
IMG_START_DATE:  15923 TJD;   362 DOY;   11/12/28
IMG_START_TIME:  56838.97 SOD {15:47:18.97} UT,   155.4 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     346780046
X_OFFSET:        982 [pixels]
Y_OFFSET:        683 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1142
Y_GRB_POS:       843
BINNING_INDEX:   1
IM_URL:          sw00510649000msuni0163.fits
SUN_POSTN:       277.14d {+18h 28m 32s}  -23.28d {-23d 16' 29"}
SUN_DIST:        130.40 [deg]   Sun_angle= 8.5 [hr] (West of Sun)
MOON_POSTN:      326.40d {+21h 45m 36s}   -8.21d {-08d 12' 47"}
MOON_DIST:       169.32 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      216.31, 49.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      145.75,  5.70 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 28 Dec 11 15:53:34 UT
NOTICE_TYPE:     Swift-UVOT Position
TRIGGER_NUM:     510649,   Seg_Num: 0
GRB_RA:          150.0666d {+10h 00m 15.98s} (J2000),
                 150.2312d {+10h 00m 55.48s} (current),
                 149.3793d {+09h 57m 31.04s} (1950)
GRB_DEC:         +18.2977d {+18d 17' 51.7"} (J2000),
                 +18.2398d {+18d 14' 23.3"} (current),
                 +18.5381d {+18d 32' 17.2"} (1950)
GRB_ERROR:       0.8 [arcsec radius, statistical only]
GRB_MAG:         17.19 +/- 0.14 [mag]
FILTER:          10, White
IMG_START_DATE:  15923 TJD;   362 DOY;   11/12/28
IMG_START_TIME:  56838.00 SOD {15:47:18.00} UT,   154.4 [sec] since BAT Trigger Time
SUN_POSTN:       277.14d {+18h 28m 33s}  -23.28d {-23d 16' 29"}
SUN_DIST:        130.36 [deg]   Sun_angle= 8.5 [hr] (West of Sun)
MOON_POSTN:      326.40d {+21h 45m 37s}   -8.21d {-08d 12' 40"}
MOON_DIST:       169.30 [deg]
MOON_ILLUM:      17 [%]
GAL_COORDS:      216.33, 49.75 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      145.78,  5.72 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT UVOT Position Notice.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The UVOT position is 10.4 arcsec from the XRT position.  
COMMENTS:        Result based on Genie data.  
COMMENTS:        Notice generated automatically.

GCN Circular #12737
T. N. Ukwatta (MSU), W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU), S. Campana (INAF-OAB), P. D'Avanzo (INAF-OAB), B. Gendre (ASDC), C. Guidorzi (U Ferrara), S. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU), H. A. Krimm (CRESST/GSFC/USRA), A. Y. Lien (NASA/GSFC/ORAU), C. B. Markwardt (NASA/GSFC), A. Melandri (INAF-OAB), J. P. Osborne (U Leicester), B. Sbarufatti (INAF-OAB/PSU), M. H. Siegel (PSU), E. Sonbas (NASA/GSFC/Adiyaman Univ.) and E. Troja (NASA/GSFC/ORAU) report on behalf of the Swift Team:
At 15:44:43 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 111228A (trigger=510649). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 150.079, +18.293 which is
```
   RA(J2000) = 10h 00m 19s
   Dec(J2000) = +18d 17' 35"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a strong triple-peaked structure with a duration of about 100 sec. The peak count rate was ~5000 counts/sec (15-350 keV), at ~93 sec after the trigger.
The XRT began observing the field at 15:47:08.6 UT, 145.1 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 150.06478, 18.29912 which is equivalent to:
```
   RA(J2000)  = 10h 00m 15.55s
   Dec(J2000) = +18d 17' 56.8"
```
with an uncertainty of 4.2 arcseconds (radius, 90% containment). This location is 53 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 in excess of the Galactic value (2.95 x 10^20 cm^-2, Kalberla et al. 2005), with an excess column of 2.4 (+2.09/-1.76) x 10^21 cm^-2 (90% confidence).
The initial flux in the 0.1 s image was 8.82e-09 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 155 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at
```
  RA(J2000)  =	10:00:16.01 = 150.06669
  DEC(J2000) = +18:17:51.8  =  18.29773
```
with a 90%-confidence error radius of about 0.75 arc sec. This position is 8.3 arc sec. from the center of the XRT error circle. The estimated magnitude is 17.19 with a 1-sigma error of about 0.14. No correction has been made for the expected extinction corresponding to E(B-V) of 0.03.
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 NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 28 Dec 11 16:04:52 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     510649,   Seg_Num: 0
POINT_RA:        150.025d {+10h 00m 06s} (J2000)
POINT_DEC:       +18.298d {+18d 17' 54"} (J2000)
POINT_ROLL:      105.316d
IMG_START_DATE:  15923 TJD;   362 DOY;   11/12/28
IMG_START_TIME:  57546.39 SOD {15:59:06.39} UT,   862.8 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.641
N_STARS:         42
X_OFFSET:        422 [pixels]
Y_OFFSET:        123 [pixels]
X_MAX:           1861 [pixels]
Y_MAX:           1562 [pixels]
DET_THRESH:      18
PHOTO_THRESH:    10
SL_URL:          sw00510649000msufc0862.fits
SUN_POSTN:       277.14d {+18h 28m 35s}  -23.27d {-23d 16' 28"}
SUN_DIST:        130.41 [deg]   Sun_angle= 8.5 [hr] (West of Sun)
MOON_POSTN:      326.50d {+21h 46m 00s}   -8.18d {-08d 10' 30"}
MOON_DIST:       169.31 [deg]
MOON_ILLUM:      18 [%]
GAL_COORDS:      216.31, 49.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      145.74,  5.70 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 28 Dec 11 16:05:06 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     510649,   Seg_Num: 0
POINT_RA:        150.025d {+10h 00m 06s} (J2000)
POINT_DEC:       +18.298d {+18d 17' 54"} (J2000)
POINT_ROLL:      105.316d
IMG_START_DATE:  15923 TJD;   362 DOY;   11/12/28
IMG_START_TIME:  57546.39 SOD {15:59:06.39} UT,   862.8 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.641
N_STARS:         42
X_OFFSET:        422 [pixels]
Y_OFFSET:        123 [pixels]
X_MAX:           1861 [pixels]
Y_MAX:           1562 [pixels]
DET_THRESH:      18
PHOTO_THRESH:    10
SL_URL:          sw00510649000msufc0862.fits
SUN_POSTN:       277.14d {+18h 28m 35s}  -23.27d {-23d 16' 28"}
SUN_DIST:        130.41 [deg]   Sun_angle= 8.5 [hr] (West of Sun)
MOON_POSTN:      326.50d {+21h 46m 00s}   -8.17d {-08d 10' 27"}
MOON_DIST:       169.31 [deg]
MOON_ILLUM:      18 [%]
GAL_COORDS:      216.31, 49.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      145.74,  5.70 [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:     Wed 28 Dec 11 16:05:29 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     510649,   Seg_Num: 0
POINT_RA:        150.025d {+10h 00m 06s} (J2000)
POINT_DEC:       +18.298d {+18d 17' 54"} (J2000)
ROLL:            105.316d
IMG_START_DATE:  15923 TJD;   362 DOY;   11/12/28
IMG_START_TIME:  57546.39 SOD {15:59:06.39} UT,   862.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     346780754
X_OFFSET:        981 [pixels]
Y_OFFSET:        682 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1141
Y_GRB_POS:       842
BINNING_INDEX:   1
IM_URL:          sw00510649000msuni0870.fits
SUN_POSTN:       277.14d {+18h 28m 35s}  -23.27d {-23d 16' 28"}
SUN_DIST:        130.41 [deg]   Sun_angle= 8.5 [hr] (West of Sun)
MOON_POSTN:      326.50d {+21h 46m 01s}   -8.17d {-08d 10' 22"}
MOON_DIST:       169.31 [deg]
MOON_ILLUM:      18 [%]
GAL_COORDS:      216.31, 49.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      145.74,  5.70 [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:     Wed 28 Dec 11 16:06:00 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     510649,   Seg_Num: 0
GRB_RA:          150.0672d {+10h 00m 16.12s} (J2000),
                 150.2318d {+10h 00m 55.62s} (current),
                 149.3799d {+09h 57m 31.18s} (1950)
GRB_DEC:         +18.2977d {+18d 17' 51.7"} (J2000),
                 +18.2398d {+18d 14' 23.3"} (current),
                 +18.5381d {+18d 32' 17.2"} (1950)
GRB_ERROR:       2.1 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  15923 TJD;   362 DOY;   11/12/28
IMG_START_TIME:  57045.00 SOD {15:50:45.00} UT,   361.4 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       277.15d {+18h 28m 35s}  -23.27d {-23d 16' 28"}
SUN_DIST:        130.37 [deg]   Sun_angle= 8.5 [hr] (West of Sun)
MOON_POSTN:      326.51d {+21h 46m 02s}   -8.17d {-08d 10' 16"}
MOON_DIST:       169.30 [deg]
MOON_ILLUM:      18 [%]
GAL_COORDS:      216.33, 49.75 [deg] galactic lon,lat of the burst
ECL_COORDS:      145.78,  5.72 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        This is an Update Notice -- the RA,Dec values herein supersede the previous XRT_POS Notice.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        This position was enhanced using UVOT field astrometry.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.58% < P(seren) < 1.1%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 28 Dec 11 16:05:42 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     510649,   Seg_Num: 0
POINT_RA:        150.025d {+10h 00m 06s} (J2000)
POINT_DEC:       +18.298d {+18d 17' 54"} (J2000)
ROLL:            105.316d
IMG_START_DATE:  15923 TJD;   362 DOY;   11/12/28
IMG_START_TIME:  57546.39 SOD {15:59:06.39} UT,   862.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     346780754
X_OFFSET:        981 [pixels]
Y_OFFSET:        682 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1141
Y_GRB_POS:       842
BINNING_INDEX:   1
IM_URL:          sw00510649000msuni0870.fits
SUN_POSTN:       277.15d {+18h 28m 35s}  -23.27d {-23d 16' 28"}
SUN_DIST:        130.41 [deg]   Sun_angle= 8.5 [hr] (West of Sun)
MOON_POSTN:      326.51d {+21h 46m 01s}   -8.17d {-08d 10' 20"}
MOON_DIST:       169.31 [deg]
MOON_ILLUM:      18 [%]
GAL_COORDS:      216.31, 49.71 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      145.74,  5.70 [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 #12738
L.P. Xin, J. Z. Li, J.Y. Wei, Y. L. Qiu, J. Wang, J.S. Deng, C. Wu, X. H. Han on behalf of EAFON report:
We began to observe GRB 111228A (Ukwatta et al., GCN 12737) with Xinglong TNT telescope at 15:46:18 (UT), about 96 sec after the burst. A series of White, R-band images were obtained. The optical counterpart (Ukwatta et al., GCN 12737) was detected in all the images. The brightness of OT is about 16.5 magnitude at the mean time of 106 sec after the burst, relatively to USNO B1.0 catalogure.
Follow-up observations are ongoing.
This message may be cited.
For more information about Xinglong GRBs Follow-up observations, please visit the website: http://www.xinglong-naoc.org:8080/grb/index.html"
GCN Circular #12741
Guver, T. (Sabanci Univ.)
The field of the GRB 111228A (Ukwatta et al. GCN 12737) was observed =20 with the SDSS survey (Abazajian et al. 2009, ApJS, 182, 543).
Within 2.2 arcseconds of the XRT coordinates, SDSS detected a galaxy name= ly SDSS J100015.45+181755.1. The exact coordinates of the galaxy are given a= s RA : 150.06439037, DEC : +18.29865952 (J2000).
SDSS magnitudes of the galaxy are :
```
u =3D 21.99 +/- 0.20
g =3D 21.34 +/- 0.05
r =A0=3D 20.90 +/- 0.05
i =A0=3D 20.72 +/- 0.06
z =3D 20.72 +/- 0.21
```
SDSS also provides a photometric redshift for the galaxy as z =3D =20 0.192859 +/- 0.04821.
For further information SDSS page for the galaxy is : http://skyserver.sdss3.org/dr8/en/tools/explore/obj.asp?id=3D1237667734494445890
GCN Circular #12742
Klotz A. (IRAP-CNRS-OMP), Gendre B. (ASDC/INAF-OAR), Boer M. (OHP-CNRS), Atteia J.L. (IRAP-CNRS-OMP) report:
We imaged the field of GRB 111228A detected by SWIFT (trigger 510649) with the TAROT robotic telescope (D=25cm) located at the Calern observatory, France.
The trigger occured during daytime over Calern. The observations started 289 min after the GRB trigger The elevation of the field increased from 7 degrees above horizon and weather conditions were good.
We detect the candidate couterpart mentioned by Ukwatta et al. (GCNC 12737) and confirmed by Xin et al. (GCNC 12738) using a co-addition of 10 images of 3mins. Surprisingly, the OT is bright R~18 (Tstart=289 min, Tend=336 min) corresponding to an optical decay alpha~0.3 taken TNT and TAROT data. We suspect a rebrightening occured during the first minutes after the trigger.
Netherveless, the low elevation and the 3 arcsec/pix sampling of TAROT does not allow to discriminate the OT from the star NOMAD1 1082-0210617 (RA=150.0646861 DEC=+18.2997694 R=19.9). Now TAROT continues observations in better airmass conditions but other observations are encouraged.
This message may be cited.
GCN Circular #12743
D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ), S. Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto) and N. Kawai(Tokyo Tech) report on behalf of the MITSuME collaboration:
We observed the field of GRB 111225A (Ukwatta et al., GCNC 12737) with the optical three color (g', Rc and Ic) CCD camera attached to the MITSuME 50cm telescope of Okayama Astrophysical Observatory.
The observation started on 2011-12-28 15:47:03 UT (~2.3 min after the burst). We detected the previously reported afterglow (Ukwatta, GCNC 12737; Xin et al., GCNC 12738) in all the three bands.
Photometric results and are listed below. We used SDSS catalog for flux calibration.
```
#T0+[day]  MID-UT    T-EXP[sec]   g'  g'_err   Rc  Rc_err   Ic  Ic_err
----------------------------------------------------------------------
0.00511    15:52:04     540.0   17.45  0.06  17.13  0.05   16.52  0.05
----------------------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]
```
GCN Circular #12744
M. S. Briggs (UAH) and G. Younes (USRA) report on behalf of the Fermi GBM Team:
"At 15:45:30.80 UT on 28 Dec 2011, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 111228A (trigger 346779932 / 111228657), which was also detected by the Swift BAT/XRT/UVOT (Ukwatta et al. 2011, GCN 12737). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 70 degrees.
The GBM light curve shows multiple peaks in three groups with a duration (T90) of about 100 s (50-300 keV) starting 50 seconds before the GBM trigger time. The time-averaged spectrum from T0+0 s to T0+57 s is well fit by a power law function with an exponential high-energy cutoff. The power law index is -1.9 +/- 0.1 and the cutoff energy, parameterized as Epeak, is 34 +/- 4 keV A Band function fits the spectrum equally well with Epeak= 34 +/- 3 keV, alpha = -1.9 +/- 0.1 and beta = -2.7 +/- 0.3.
The event fluence (10-1000 keV) in this time interval is 1.8E-5 erg/cm^2. The 64 ms peak photon flux measured starting from T0+7.7 s in the 10-1000 keV band is 27 +/- 1 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN Circular #12745
S. B. Pandey, Vijay Kumar Bhatt, Brajesh Kumar and Ram Kesh Yadav (ARIES, NainiTal, India, on behalf of larger Indian GRB collaboration).
We have observed GRB 111228A field (Ukwatta et al., GCN 12737; Briggs and Younes, GCN 12744) with the 1.04m telescope at ARIES NainiTal starting ~1.9 hours post-burst. Several sets of exposures varying 100s to 300 s each were taken in Bessel filters. The afterglow candidate (Xin et al., GCN 12738) is visible in individual frames.
Preliminary photometry of the R_c band data in comparison to nearby USNO stars, indicates that the afterglow candidate has decayed by ~ 0.7 mag in ~ 3.5 hours of observations. This corresponds to a temporal decay index of ~ 0.3, similar to what has been noticed by Klotz et al. (GCN 12742). Further observations are continued.
This message may be cited.
GCN Circular #12746
Klotz A. (IRAP-CNRS-OMP), Gendre B. (ASDC/INAF-OAR), Boer M. (OHP-CNRS), Atteia J.L. (IRAP-CNRS-OMP) report:
We continue to obtain images of the field of GRB 111228A detected by SWIFT (trigger 510649) with the TAROT robotic telescope (D=25cm) located at the Calern observatory, France (cf. GCNC 12742).
We confirm the OT observed by TAROT is not the galaxy mentioned by Guver (GCNC 12741) neither the object referenced as NOMAD1 1082-0210617 (Klotz GCNC 12742). The OT observed by TAROT is the afterglow of GRB 111228A and lies 9 arcsec eastern from these objects.
As we previously announced (GCNC 12742), we confirm that the OT of GRB 111228A is brighter than a simple extrapolation of the very early observations using a standard decay. Current TAROT observations show that the decay is stopped.
Unfiltered TAROT images were co-added to obtain a temporal series that shows clearly that the brightness remains almost constant since the beginning of the TAROT observations.
Photometry is relative to the star NOMAD1 1083-0203467 (RA=150.0946028 DEC=+18.3231806 J2000) R=17.28 (V-R)=+0.69.
```
  Tstart   Tend   Rmag OT
    (min)  (min)
     289    318   18.6 +/- 0.4
     321    352   18.9 +/- 0.4
     358    389   18.5 +/- 0.3
     392    421   18.7 +/- 0.3
     429    459   18.7 +/- 0.3
     462    492   18.9 +/- 0.3
```
This message may be cited.
GCN Circular #12747
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team.
Using 1689 s of XRT Photon Counting mode data and 3 UVOT images for GRB 111228A, 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 = 150.06699, +18.29781 which is equivalent to:
```
RA (J2000): 10h 00m 16.08s
Dec (J2000): +18d 17' 52.1"
```
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) 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 #12748
V. Nascimbeni (Univ. Padova), E. Palazzi (INAF-IASFBo), D. Fugazza, A. Melandri, S. Covino (INAF-OABr), L. Borsato, A. Cunial, V. Granata (Univ. Padova), report on behalf of a larger collaboration:
We observed the field of GRB 111228A (Ukwatta et al., GCN 12737) with the 1.82m Asiago Telescope equipped with the AFOSC optical camera. A 900 s R-band image was acquired with mean time Dec 28.939 UT (6.79 hr after the burst trigger).
We clearly detect the afterglow (Ukwatta et al., GCN 12737; Xin et al., GCN 12738; Klotz et al., GCN 12472) at a magnitude R = 18.6 +/- 0.02 assuming R = 17.28 for the star USNO-B1 1083-0199833 (RA = 10:00:22.72, Dec = +18:19:23.85 - same as used by Klotz et al., GCN 12746).
We also clearly detect the SDSS object reported by Guver (GCN 12741), and confirm that it is not related to the GRB (Klotz et al., GCN 12746). Further observations are underway.
GCN Circular #12749
J. R. Cummings (GSFC/UMBC),S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), 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+746 sec from the recent telemetry downlink, we report further analysis of BAT GRB 111228A (trigger #510649) (Ukwatta, et al., GCN Circ. 12737). The BAT ground-calculated position is RA, Dec = 150.063, 18.284 deg which is
```
     RA(J2000)  =  10h 00m 15.0s
     Dec(J2000) = +18d 17' 02.2"
```
with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 39%.
The mask-weighted light curve shows multiple peaks in several clusters. The first set of peaks is at a low level from T-12 s to T+12 s. There is another low level set from T+32 to T+42 s, followed by a much brighter set of three overlapping peaks from T+45 to T+60 s. The final cluster is broad and relatively soft from T+85 to T+110 s. T90 (15-350 keV) is 101.20 +- 5.42 sec (estimated error including systematics).
The time-averaged spectrum from T-12.82 to T+115.43 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.27 +- 0.06. The fluence in the 15-150 keV band is 8.5 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+54.56 sec in the 15-150 keV band is 12.4 +- 0.5 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/510649/BA/
GCN Circular #12750
D. Xu (WIS/NAOC), J. McCormac (Queen's Univ. Belfast), and P. Jakobsson (Univ. Iceland) report on behalf of a larger collaboration:
We observed the field of GRB 111228A (Ukwatta et al., GCN 12737) with the 2.5m Nordic Optical Telescope (NOT) equipped with the AFOSC optical camera. A 600s R-band image was taken with mean time 01:32 UT on 2011-12-29 (9.8 hr after the burst trigger).
We clearly detected the afterglow (Ukwatta et al., GCN 12737; Xin et al., GCN 12738; Klotz et al., GCN 12742) at a magnitude R = 19.01 +/- 0.05, calibrated with the USNO-B1 1083-0199833 star (R2 = 17.28 mag; also used by Klotz et al., GCN 12746 and Nascimbeni et al., GCN 12748).
Further observations are ongoing.
GCN Circular #12751
M. Nysewander, J. Haislip, K. Ivarsen, A. LaCluyze, M. Maturi, D. Reichart, J. Moore, T. Cromartie, R. Egger, A. Foster, N. Frank, A. Oza, E. Speckhard, A.Trotter, and J. A. Crain report:
Skynet observed the field of GRB 111228A (Ukwatta et al., GCN 12737) with the 16" Dolomites Astronomical Observatory telescope (DAO) in Italy beginning 6.4 hrs after the burst, and lasting for one hour.
We detect the afterglow in g' (11 x 180s) and r' (7 x 180s) exposures. Using ~20 SDSS field stars, we measure the OT to be g' = 19.4 +- 0.1 at 6.73 hours and r' = 19.3 +- 0.2 at 7.30 hours in stacked images. The OT faded by r' ~ 0.1 mag from 7.15 to 7.41 hours.
GCN Circular #12752
N. P. M. Kuin (MSSL-UCL) and Ukwatta (MSU) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 111228A 155 s after the BAT trigger (Ukwatta et al., GCN Circ. 12737). The UVOT position is consistent with the enhanced XRT position (Goad et al., GCN Circ. 12747) within the measurement accuracy.
Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white              155          305          147         17.30 +/- 0.03
v                  389          759           58         17.73 +/- 0.16
b                  488          508           19         17.71 +/- 0.15
u                  463          483           19         16.70 +/- 0.12
w1                 439          459           19         16.59 +/- 0.17
m2                 764          784           19         16.84 +/- 0.24
```
The preliminary lightcurves show achromatic behavior during the first 1200s and appears to maintain brightness levels until around 7000s after the trigger, when the decay in brightness sets in.
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.03 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #12753
J. Gorosabel (IAA-CSIC), R. Gimeno (IAC), A. Nicuesa Guelbenzu (TLS Tautenburg), report on behalf of a larger collaboration:
"We observed the field of GRB 111228A (Ukwatta et al., GCNC 12737) with the 82cm IAC80 telescope at the Observatorio del Teide, Tenerife, Spain. The observations were carried in the BVI-bands on Dec 29.08662 - 29.19141 UT (10.3-12.8 hours post burst). The optical afterglow of the burst (Ukwatta et al., GCNC 12737; Xin et al., GCNC 12738; Klotz et al., GCNC 12742; Pandey et al. GCN 12745; Nascimbeni et al. GCNC 12748; Xu et al., GCNC 12750; Nysewander et al. GCN 12751; Kuin et al. GCN 12752) is well detected in the three bands with an approximate magnitude of I~18.5 with respect to the USNO B1.0 catalogue."
GCN Circular #12754
Veli-Pekka Hentunen, Markku Nissinen and Tuomo Salmi (Taurus Hill Observatory, Varkaus, Finland) report:
GRAS 017 (Global-Rent-a-Scope, Nerpio, Spain) CDK17 17" (0.43 m) f/6.8 and FLI ProLine CCD camera were used to detect GRB 111228A optical afterglow 9.0 hours after the burst trigger. The observations were started at 2011-12-29 00:35:06 (UT) and stopped at 2011-12-29 00:58:26 (UT). Nine photometric R observations with 120s exposure times were made. The afterglow was detected at following position RA 10 00 16.07 and DEC +18 17 52.1.
The following magnitude was obtained from the observations using USNO-B1 1083-0199853 (R2 = 17.28) as the comparison:
```
Tmid(s)+T0    Filter        Exp (sec)     Mag      Mag err   Limit
32522               R           9x120          18.7        0.2        19.8
```
A png image of our observations is available at the following URL link: http://cutenews.kassiopeia.net/data/upimages/GRB111228A_web.png
GCN Circular #12755
D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ), S. Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto) and N. Kawai(Tokyo Tech) report on behalf of the MITSuME collaboration:
The GRB name reported in GCNC 12743 is incorrect. We revise as follows:
We observed the field of GRB 111228A (Ukwatta et al., GCNC 12737) with the optical three color (g', Rc and Ic) CCD camera attached to the MITSuME 50cm telescope of Okayama Astrophysical Observatory.
GCN Circular #12756
E. Sinykov, V.Yurkov, Yu.Sergienko, D.Varda, Blagoveschensk Educational State University, Blagoveschensk
E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, N.Tyurina, N.Shatskiy, P.Balanutsa, V.V.Chazov, A.Kuznetsov, D.Zimnukhov, M. Kornilov, A.Kuznetsov, D.Zimnukhov, M. Kornilov, A.Sankovich, S. Shurpakov Sternberg Astronomical Institute, Moscow State University
K.Ivanov, V.A.Poleshchuk, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev,E.Konstantinov, Irkutsk State University
A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory
V.Krushinski, I.Zalozhnich, A. Popov Ural State University, Kourovka
MASTER II robotic double telescope (MASTER-Net: http://observ.pereplet.ru) located in Blagoveschensk was pointed to the GRB111228.66 191 sec after notice time and 244 sec after GRB time at 2011-12-28 15:48:47.127 UT. The some delay was due to weather conditions. On our first (20s exposure, two polarizations, unfiltered) set we found optical transient at Swift OT position (Ukwatta et al., GCN Circ R12737). The OT magnitude is about 16.5 mag in both polarizations.
The reduction is continuated.
The message may be cited.

GCN Notice >BR>

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 29 Dec 11 05:54:11 UT
NOTICE_TYPE:     Swift-BAT Slew GRB Position
ID_NUM:          723
GRB_RA:          150.090d {+10h 00m 22s} (J2000),
                 150.255d {+10h 01m 01s} (current),
                 149.403d {+09h 57m 37s} (1950)
GRB_DEC:         +18.300d {+18d 18' 00"} (J2000),
                 +18.242d {+18d 14' 32"} (current),
                 +18.540d {+18d 32' 26"} (1950)
GRB_ERROR:       1.83 [arcmin radius, statistical only]
GRB_INTEN:       873366 [cnts]    Image_Peak=17442 [image_cnts]
TRIGGER_DUR:     91.000 [sec]  
TRIGGER_INDEX:   10     Criteria: S(15-50) > 4.0 sigma  AND  H(50-150) > 4.0 sigma 
ENERGY_RANGE:    15-150 keV
BKG_INTEN:       1426369 [cnts]
BKG_TIME:        56564.31 SOD {15:42:44.31} UT
BKG_DUR:         166 [sec]
GRB_DATE:        15923 TJD;   362 DOY;   11/12/28
GRB_TIME:        56730.56 SOD {15:45:30.56} UT
SOLN_STATUS:     0x30000013    
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    46.40 [sigma] 
SUN_POSTN:       277.78d {+18h 31m 08s}  -23.24d {-23d 14' 39"}
SUN_DIST:        130.93 [deg]   Sun_angle= 8.5 [hr] (West of Sun)
MOON_POSTN:      333.39d {+22h 13m 34s}   -5.48d {-05d 28' 34"}
MOON_DIST:       166.87 [deg]
MOON_ILLUM:      22 [%]
GAL_COORDS:      216.34, 49.77 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      145.80,  5.73 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT Slew GRB Coordinates.
COMMENTS:        A point_source was found.
COMMENTS:        This does not match any source in the ground catalog.
COMMENTS:        This is a GRB. 
COMMENTS:        Extremely high confidence of reality (gold-plated).
COMMENTS:        This Notice was ground-processed from flight-data.
COMMENTS:        
COMMENTS:        NOTE: This BAT event is spatially(0.00<0.1deg) and temporally(0.0<100sec) coincident with the SWIFT_BAT event (trignum=510649).
COMMENTS:

GCN Circular #12757
A. Nicuesa Guelbenzu, S. Klose (both TLS Tautenburg), and J. Greiner (MPE Garching) report on behalf of the GROND team:
We observed the field of GRB 111228A (Ukwatta et al., GCN 12737) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2-m MPG/ESO telescope on La Silla.
Observations started as soon the object was visible over La Silla, at 04:46 UT on December 29, about 13 hr after the burst. We detect the afterglow (Ukwatta et al., GCN 12737; Xin et al., GCN 12738) in all bands. At a mean time of December 29, 05:35 UT, in an 8min exposure, we measure the following preliminary magnitudes (AB system):
```
    g' = 20.17  +/- 0.01,
    r' = 19.84  +/- 0.01,
    i' = 19.67  +/- 0.02,
    z' = 19.50  +/- 0.03,
    J  = 19.29  +/- 0.07,
    H  = 18.93  +/- 0.08.
```
The SED is best fit with a spectral slope of 0.90 +/- 0.05, with no evidence for additional extinction.
Optical data are calibrated against SDSS and NIR data against 2MASS field stars. Observations are continuing.
GCN Circular #12758
Klotz A. (IRAP-CNRS-OMP), Gendre B. (ASDC/INAF-OAR), Boer M. (OHP-CNRS), Atteia J.L. (IRAP-CNRS-OMP) report:
We continue to obtain images of the field of GRB 111228A detected by SWIFT (trigger 510649) with the TAROT robotic telescope (D=25cm) located at the European Southern Observatory, La Silla observatory, Chile (early observations were done using TAROT Calern, reported in GCNC 12742 and GCNC 12746).
Photometry is relative to the star NOMAD1 1083-0203467 (RA=150.0946028 DEC=+18.3231806 J2000) R=17.28 (V-R)=+0.69.
```
  Tstart   Tend   Rmag OT
    (min)  (min)
     788    837   19.0 +/- 0.4
     840    890   19.2 +/- 0.3
```
Taking account for the magnitudes obtained earlier from TAROT Calern we deduce that the plateau phase may be now finished and an optical decay of ~0.5 could now occur.
This message may be cited.
GCN Circular #12759
J. Dittman, T. Laskar, and E. Berger (Harvard) report:
"Starting on 2011 December 29.312 UT (15.7 hours after the burst) we used the Blue Channel spectrograph mounted on the MMT 6.5-m telescope to observe GRB111228A (GCN #12737). Our spectra cover the range 3400-8500A and reveal absorption lines of MgII and FeII at a common redshift of z=0.714, which we consider to be the redshift of GRB111228A. Additional observations are in progress."
GCN Circular #12760
GRB 111228A: PAIRITEL NIR Detection
A. N. Morgan (UC Berkeley) reports:
We observed the field of GRB 111228A (Ukwatta et al., GCN 12737) with the 1.3m PAIRITEL located at Mt. Hopkins, Arizona. Observations began at 2011-12-29 06:55:25 UT, ~15.2 hours after the Swift Trigger. In mosaics (effective exposure time of 0.46 hours) taken simultaneously in the J, H, and Ks filters, we marginally detect a source at the optical afterglow location (Ukwatta et al., GCN 12737; Xin et al., GCN 12738; Klotz et al., GCN 12742; Pandey et al., GCN 12745; Nascimbeni et al., GCN 12748; Xu et al. GCN 12750; Nysewander et al., GCN 12751; Kuin & Ukwatta, GCN 12752; Gorosabel et al., GCN 12753; Hentunen et al., GCN 12754; Sinykov et al., GCN 12756; Guelbenzu et al., GCN 12757).
The preliminary photometry yields:
```
post burst
t_mid (hr) exp.(hr) filt  mag    m_err
15.56      0.46     J     18.3   0.2
15.56      0.46     H     17.8   0.3
15.56      0.46     Ks    16.2   0.3
```
All magnitudes are given in the Vega system, calibrated to 2MASS. No correction for Galactic extinction has been made to the above reported values. Further observations are ongoing.
GCN Circular #12761
A. Cucchiara (UCSC/UCO Lick), A. J. Levan (U. Warwick), and S. B. Cenko (UC Berkeley) report:
We obtained spectroscopy of the optical afterglow of GRB 111228A (Ukwatta et al., GCN 12737) using GMOS-South on the Gemini-South 8-m telescope. Observations began on December 29.28 UT (15 hrs after the BAT trigger).
Inspection of the first two exposures (range 4160-8140 Angstroms) reveals MgII2796,2803, MgII2853 and CaH&K absorption features at a common redshift of 0.716.
We therefore suggest this to be the redshift of GRB 111228A.
We thank the Gemini staff for performing this observation, in particular Pascale Hibon.
GCN Circular #12762
E. Sinykov, V.Yurkov, Yu.Sergienko, D.Varda, Blagoveschensk Educational State University, Blagoveschensk
E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, N.Tyurina, N.Shatskiy, P.Balanutsa, V.V.Chazov, A.Kuznetsov, D.Zimnukhov, M. Kornilov, A.Kuznetsov, D.Zimnukhov, M. Kornilov, A.Sankovich, S. Shurpakov Sternberg Astronomical Institute, Moscow State University
K.Ivanov, V.A.Poleshchuk, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev,E.Konstantinov, Irkutsk State University
A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory
V.Krushinski, I.Zalozhnich, A. Popov Ural State University, Kourovka
2 cameras MASTER VFW (FOV=2x420 sq.deg.) located in Blagoveschensk made observations synchronously with this GRB111228.45 (Trigger Number 346779932) from it cover 3-sigma error-box. The detailed map of a covering is available here http://master.sai.msu.ru/static/GRB/Amur/FERMI/Amur.grb_1_235392.png and on following table 1
Table 1. Synchronous GRB observations
```
   ID_CAM ID_SET    RA. [deg]    Dec.[deg]  Limit Exptime
   29009  21381    21.566667    21.999722   11.5    5.00
  100627   3913    15.201755    18.989718   11.5    5.00
```
MASTER-2 and MASTER VFW pointed to GRB111228.45 54 sec after the trigger time and 24 sec after the notice time. The MASTER-2 (FOV=4 sq.deg.) first image upper limit is 15. 7 . MASTER VWF cover 1 and 3 sigma errorboxes.The detailed map of a covering is available here http://master.sai.msu.ru/static/GRB/Amur/FERMI/Amur.grb_2_235392.png and on following table 2:
Table 2. GRB follow up observations.
```
  ID_CAM ID_SET    RA. [deg]    Dec.[deg]  Limit Exptime
   29009  21382   346.616940     9.675031   11.2    5.00
  100627   3914   335.179167    10.132500   11.2    5.00
```
The reduction is continuated.
The message may be cited.
GCN Circular #12763
E. Palazzi (INAF-IASFBo), D. Fugazza (INAF-OAB), S. Piranomonte (INAF-OAR) on behalf of a larger collaboration report:
The afterglow of GRB 111228A (Ukwatta et al. GCN 12737) was observed with the DOLORES instrument mounted at the Telescopio Nazionale Galileo on La Palma, Canary Islands. Starting on December 29.1200 (~11 hour after the burst), a series of three spectra of 1800s each were secured with LR-B grism (range 3500-8000 Angstroms).
Preliminary reduction of the spectra reveals absorption features that we identify with the following absorption lines:
```
Lines ID       Lambda_observed
              (Angstroms)
FeII_2344.21   4019.83
FeII_2374.46   4073.40
FeII_2382.76   4088.32
FeII_2585.65   4436.05
FeII_2600.17   4460.64
MgII_2795.50   4795.65
MgII_2802.70   4808.58
MgI_2852.96    4891.53
CaII_3933.68   6756.61
CaII_3968.49   6807.44
```
The derived redshift is z=3D0.7156 =B1 0.0005 which confirms the results obatined by Dittman et al. (GCN 12759) and Cucchiara et al (GCN 12761).
In addition to the GRB afterglow we observed the SDSS galaxy reported by Guver (GCN 12741). We detect many emission lines (OII_3726+3728, Hbeta, OIII_4958, OIII_5006, Halpha) at a common redshift of 0.218 =B1 0.001 which is in agreement with the reported photometric redshift. This galaxy is therefore not related to the GRB.
We acknowledge the excellent support from the TNG staff, in particular Walter Boschin and Gianni Tessicini
GCN Circular #12764
D. Xu (WIS/NAOC), J.P.U. Fynbo (DARK), J. McCormac (Queen's Univ. Belfast), and P. Jakobsson (Univ. Iceland) report on behalf of a larger collaboration:
We secured spectroscopy of the afterglow of GRB 111228A (Ukwatta et al., GCN 12737) with the 2.5m Nordic Optical Telescope (NOT) equipped with the ALFOSC optical camera. Observations started immediately after the 600s R-band photometry in Xu et al. (GCN 12750).
The NOT spectrum covers 2750-9000A and shows clear absorption lines of MgII2803 and CaH&K, at a common redshift of z=0.713.
Further observations are planned.
GCN Circular #12765
E. Palazzi (INAF-IASFBo), D. Fugazza (INAF-OAB), S. Piranomonte (INAF-OAR) on behalf of a larger collaboration report:
The afterglow of GRB 111228A (Ukwatta et al. GCN 12737) was observed with the DOLORES instrument mounted at the Telescopio Nazionale Galileo on La Palma, Canary Islands. Starting on December 29.1200 (~11 hour after the burst), a series of three spectra of 1800s each were secured with LR-B grism (range 3500-8000 Angstroms).
Preliminary reduction of the spectra reveals absorption features that we identify with the following absorption lines:
```
Lines ID       Lambda_observed
               (Angstroms)
FeII_2344.21   4019.83
FeII_2374.46   4073.40
FeII_2382.76   4088.32
FeII_2585.65   4436.05
FeII_2600.17   4460.64
MgII_2795.50   4795.65
MgII_2802.70   4808.58
MgI_2852.96    4891.53
CaII_3933.68   6756.61
CaII_3968.49   6807.44
```
The derived redshift is z=0.7156 +/- 0.0005 which confirms the results obatined by Dittman et al. (GCN 12759) and Cucchiara et al (GCN 12761).
In addition to the GRB afterglow we observed the SDSS galaxy reported by Guver (GCN 12741). We detect many emission lines (OII_3726+3728, Hbeta, OIII_4958, OIII_5006, Halpha) at a common redshift of 0.218 +/- 0.001 which is in agreement with the reported photometric redshift. This galaxy is therefore not related to the GRB.
We acknowledge the excellent support from the TNG staff, in particular Walter Boschin and Gianni Tessicini
GCN Circular #12766
P. D'Avanzo (INAF-OAB) and T. N. Ukwatta (MSU) report on behalf of the Swift-XRT team:
We have analysed 6.4 ks of XRT data for GRB 111228A (Ukwatta et al. GCN Circ. 12737), from 135 s to 29.3 ks after the BAT trigger. The data comprise 331 s in Windowed Timing (WT) mode (the first 9 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Goad et al. (GCN. Circ 12747).
The light curve can be modelled with a series of power-law decays. The initial decay index is alpha=5.41 (+0.09, -0.07). At T+418 s the decay flattens to an alpha of 0.26 (+0.05, -0.06) before breaking again at T+6950 s to a final decay with index alpha=1.27 (+0.19, -0.15).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 4.16 (+0.12, -0.11). The best-fitting absorption column is 2.92 (+0.18, -0.17) x 10^21 cm^-2, in excess of the Galactic value of 3.0 x 10^20 cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a photon index of 2.19 (+0.11, -0.10) and a best-fitting absorption column of 1.52 (+0.27, -0.26) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.4 x 10^-11 (5.2 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     1.52 (+0.27, -0.26) x 10^21 cm^-2
Galactic foreground: 3.0 x 10^20 cm^-2
Excess significance: 7.9 sigma
Photon index:	     2.19 (+0.11, -0.10)
```
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00510649.
This circular is an official product of the Swift-XRT team.
GCN Circular #12767
```
Dear Scott, 
      Please change my affiliation into Yunnan observatory (YNAO). Thank you so much.
best,
XH
```
X.-H. Zhao (YNAO), D. Xu (WIS/NAOC), J.-R. Mao (KASI/YNAO), J.-M. Bai (YNAO) report:
We observed the field of GRB 111228A (Ukwatta et al., GCN 12737) at the 2.4m Gao-Mei-Gu (GMG) telescope equipped with YFOSC. Observations started at 16:31:38 UT on 2011-12-28 (i.e., 47 mins after the burst) and 4x600s R-band images were obtained in a seeing of ~3.36". We found the afterglow was decaying. The results are as follows:
```
mid time (UT)                            magnitude (err)
 2011-12-28 16:36:38                     17.11 (0.01)  
 2011-12-28 17:19:14                    17.42 (0.01)  
 2011-12-28 17:44:57                    17.56 (0.01)  
 2011-12-28 17:56:15                    17.62 (0.01). 
```
The magnitudes were calibrated with the USNO-B1 #1083-0199833 star (R2 = 17.28 mag; also used by Klotz et al., GCN 12746; Nascimbeni et al., GCN 12748; Xu et al., GCN 12750; Hentunen et al., GCN 12754).
Further observations are planned.
We thank the GMG staff, especially Y.-X. Xin, Fen He, and Gui-Hua He for performing these observations.
GCN Circular #12768
R. Usui, Y. Aoki, S. Song, M. Hayashi, K. Kawakami, K. Tokoyoda, Y. Saito, Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration:
We observed the field of GRB 111228A (Ukwatta et al., GCNC 12737) with the optical three color (g', Rc and Ic) CCD camera attached to the MITSuME 50cm telescope of Akeno Observatory, Yamanashi, Japan.
The observation started on 2011-12-28 15:45:47 UT (~ 64 sec after the burst). We detected the previously reported afterglow (Ukwatta, GCNC 12737; Xin et al., GCNC 12738) in all the three bands.
Photometric results and are listed below. We used GSC2.3 catalog for flux calibration.
```
#T0+[day]  MID-UT    T-EXP[sec]   g'  g'_err   Rc  Rc_err   Ic  Ic_err
----------------------------------------------------------------------
0.00074    15:46:02     30.0   17.3  0.2  16.12  0.09   15.5  0.1
----------------------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]
```
GCN Circular #12769
T. Guver (Sabanci Univ.), E. Sonbas (Adiyaman Univ.), S. Kaynar (Akdeniz Univ.), E. Gogus (Sabanci Univ.), Z. Eker (TUG) report on behalf of a larger collaboration
We observed the field of Swift GRB 111228A (Ukwatta et al., GCN 12737) with the 1.0 meter T100 telescope (TUBITAK National Observatory, Antalya - Turkey), starting December, 28, 22:48 UT (~ 7 hours after the trigger). Observations were carried out in the B, R, and V filters under good weather conditions. The afterglow is clearly detected in all images.
Using the USNO-B1 star USNO-B1 1083-0199833 (RA = 10:00:22.72, Dec = +18:19:23.85 - same as used by Klotz et al., GCN 12746 and Nascimbeni et al., GCN 12748) in the field we estimated the following magnitudes for the OT:
```
t - t0 (h)       Exp. (s)      Filter            mag.        err
6.859            300            B               19.12      +/- 0.04
6.958            300            B               19.56      +/- 0.07
8.219            300            B               19.58      +/- 0.04
8.317            300            B               19.39      +/- 0.05
7.057            300            R               18.45      +/- 0.02
7.155            300            R               18.50      +/- 0.02
8.416            300            R               18.58      +/- 0.02
8.514            300            R               18.61      +/- 0.03
```
We are grateful to the TUBITAK National Observatory staff for promptly scheduling the observations and their technical support.
GCN Circular #12770
S. Schulze (U Iceland), S. Covino (INAF-OABr), H. Flores (GEPI/Obs. de Paris), J. P. U. Fynbo (DARK/NBI), B. Milvang-Jensen (DARK/NBI), J. Sollerman (U Stockholm), D. Xu (WIS) report on behalf of the X-shooter GRB collaboration:
We observed the afterglow of GRB 111228A (Ukwatta et al. GCN 12737) with the ESO VLT equipped with the X-shooter spectrograph on 29 December 2011, beginning 07:40 UT (15.93 hr after the GRB). The afterglow had an R-band brightness of 20.08 mag in a series of five acquisition images with an exposure time of 30 s each (mid-exposure time = 15.98 hours). The magnitude is not corrected for Galactic extinction.
We acquired four spectra with an exposure time of 600 seconds each, beginning at 07:47 UT. We detect several absorption lines
```
wave_obs wave_rest  Ion     redshift
(AA, vac)   (AA, vac)
3880.28     2260.78     FeII     0.71634
4023.15     2344.21     FeII     0.71620
4075.26     2374.46     FeII     0.71629
4089.47     2382.77     FeII     0.71627
4422.70     2576.88     MnII    0.71630
4439.44     2586.65     FeII     0.71629
4453.10     2594.50     MnII    0.71636
4462.57     2600.17     FeII     0.71626
4799.05     2796.35     MgII    0.71618
4811.32     2803.53     MgII    0.71616
4896.33     2852.96     MgI     0.71623
6753.24     3934.78     CaK    0.71630
6813.09     3969.59     CaH    0.71632
```
at a common redshift of z = 0.71627 +/- 0.00002. In addition we detect [OIII]5007 at z_em = 0.71635, similar to the absorption line redshift. Our measurements confirm the results by of Cucchiara et al (GCN 12761) and Palazzi et al (GCN 12763) and are similar to Dittmann et al (GCN 12759) and Xu et al (GCN 12764).
The seeing conditions over the entire campaign were around 0.8 arcsec.
We acknowledge the support of the VLT staff, in particular Claudio Melo and Christophe Martayan.
GCN Circular #12771
S. B. Cenko (UC Berkeley) reports on behalf of a larger collaboration:
We have imaged the field of GRB111228A (Ukwatta et al., GCN 12737) with the automated Palomar 60 inch telescope. Observations were obtained in the r' and i' filters beginning at 10:27 UT on 2011 December 29 (~ 18.9 hours after the Swift trigger).
We detect the optical afterglow with a magnitude of r' = 20.3 +/- 0.1 mag (AB, calibrated with respect to several point sources from the Sloan Digital Sky Survey in the field). Compared with previous reported measurements of the afterglow brightness, this suggests a steeper decay than observed at early times (e.g., Klotz et al., GCN 12742).
Further observations are planned.
GCN Circular #12773
A. Melandri (INAF-OAB), C. Guidorzi (U. Ferrara), C. G. Mundell (Liverpool JMU) and N. R. Tanvir (U. Leicester), on behalf of a large collaboration report:
"We observed the optical afterglow of GRB 111228A (Ukwatta et al., GCN 12737) with the 2-m Liverpool Telescope, starting at 02:55 UT on 2011 December 29. We took a sequence of images in Br'i' bands, with exposure time of 300s for each individual frame.
We clearly detect the optical afterglow in all individual images. In stacked frames we find the following magnitudes for the OT:
```
Mid time from  Total Exp   Filter    Magnitude
trigger (hr)    (s)
--------------------------------------------------
12.08          4x300       r'        19.68 +- 0.06
13.28          3x300       r'        19.89 +- 0.09
12.54          5x300       i'        19.57 +- 0.05
11.34          4x300       B         19.71 +- 0.08
12.96          4x300       B         19.79 +- 0.11
--------------------------------------------------
```
The magnitudes are calibrated against nearby SDSS-5 (r' and i' bands) and USNO-B1.0 (B band) field stars and are not corrected for the Galactic extinction.
This message may be cited."

GCN Circular #12778
X.-H. Zhao (YNAO), L. P. Xin (NAOC), J.-R. Mao (KASI/YNAO), J.-M. Bai (YNAO) report on behalf of a larger collaboration:
We made a further observation of GRB 111228A (Ukwatta et al., GCN 12737) with 2.4m Gao-Mei-Gu (GMG) telescope. Observations started at 16:07:37 UT on 2011-12-29 (i.e., ~24.4 hrs after the burst) . We found the afterglow has faded significantly. The magnitudes are as follows:

mid time (UT)                   Exp. (s)     Filter               magnitude (err)
 2011-12-29 16:12:37        600            R                    20.24 (0.12)  
 2011-12-29 16:27:55        600            V                    20.67 (0.18)
 2011-12-29 16:38:54        600            B                    21.13 (0.15) 
 2011-12-29 16:52:46        600            R                    20.33 (0.12)  
 2011-12-29 17:03:24        600            V                    20.73 (0.18)
 2011-12-29 17:14:06        600            B                    21.31 (0.16)  
 2011-12-29 17:28:50        600            R                    20.54 (0.13)  
 2011-12-29 17:39:39        600            V                    20.96(0.21)   
 2011-12-29 17:51:19        600            B                    21.40 (0.17)

The magnitudes were calibrated with the USNO-B1 #1083-0199833 star (R2 = 17.28 mag and (V-R)=+0.69; also used by Klotz et al., GCN 12746; Nascimbeni et al., GCN 12748; Xu et al., GCN 12750; Hentunen et al., GCN 12754; Klotz et al. GCN 12758).
We thank the GMG staff, especially Y.-X. Xin, Fen He, and Gui-Hua He for performing these observations.

GCN Circular #12779
A. LaCluyze, M. Nysewander, J. Haislip, K. Ivarsen, M. Maturi, D. Reichart, J. Moore, T. Cromartie, R. Egger, A. Foster, N. Frank, A. Oza, E. Speckhard, A.Trotter, and J. A. Crain report:
Skynet continued observing the field of GRB 111228A (Ukwatta et al., GCN 12737) with the PROMPT telescope array at CTIO in Chile and the 16" Dolomites Astronomical Observatory telescope (DAO) in Italy.
We detect the afterglow in g', r', i' and B, R, I bands, with a chromatic variation suggested by late time data. A preliminary light curve, calibrated to SDSS catalog sources can be found at the following link:
http://skynet.unc.edu/grb/grb111228a.png
Further observations are ongoing to attempt to confirm or refute the chromatic variation.
GCN Circular #12784
From: Bethany Cobb at GWU
Using the ANDICAM instrument on the 1.3m telescope at CTIO, we obtained optical/IR imaging of the error region of GRB 111228A (GCN 12737, Ukwatta et al.) with a mid-exposure time of 15.9 hours (2011-12-29 07:39 UT) and 39.5 hours (2011-12-30 07:13 UT) post-burst. Total summed exposure times amounted to 36 minutes in I and 30 minutes in J.
The optical afterglow of GRB 111228A (e.g. GCN 12737, Ukwatta et al.; GCN 12738, Xin et al.) is detected and observed to decay between our imaging. Preliminary comparison to Landolt standard stars in the optical and 2MASS stars in the IR indicates the following magnitudes for the afterglow:
```
time post-burst       I mag             J mag
15.9 hours            19.3 +/- 0.1      20.6 +/- 0.1
39.5 hours            18.4 +/- 0.1      > 19.1 (3-sigma limit)
```
This indicates that the decay rate of the burst between ~16 and 40 hours post burst is alpha ~ 1.3 (where afterglow flux is proportional to t^-alpha). In agreement with Cenko et al. (GCN 12771), this later-time decay is much steeper than the earlier-time decay noted by Klotz et al. (GCN 12742) and Pandey et al. (GCN 12745).
GCN Circular #12785
From: Bethany Cobb at GWU
The data in the table in GCN 12784 was incorrectly placed. The corrected table is given below.
```
time post-burst      I mag              J mag
15.9 hours            19.3 +/- 0.1      18.4 +/- 0.1
39.5 hours            20.6 +/- 0.1       > 19.1 (3-sigma limit)
```
We apologize for any confusion. We thank Adam Miller for pointing out this error.
GCN Circular #12787
R. Itoh, K. Takaki, M. Yamanaka, M. Sasada, K. Sakimoto, M. Yoshida, K. S. Kawabata, Y. Hanabata, M. Ohno, Y. Fukazawa (HiroshimaUniv.), A. Nakashima (Tokyo Univ.) report on behalf of the Kanata collaboration:
We performed optical and near infrared observations of GRB 111228A (Ukwatta et al., GCN 12737; Xin et al., GCN 12738) with the 1.5 m Kanata Telescope of Higashi-Hiroshima observatory, Japan. The observation started at 15:47 UT on 2011 December 28. We took a sequence of images in Rc and K bands, and detected the optical-infrared afterglow of the GRB (Veli-Pekka Hentunen et al. GCN 12754; Kuroda et al. GCN 12743; Nicuesa Guelbenzu et al. GCN 12757; Usui et al. GCN 12768).
Photometric results are listed below. We used USNO-B1 catalog for flux calibration of Rc band, and 2-MASS catalog for Ks band.
```
Mid time from  Total Exp   Filter    Magnitude
trigger (hr)    (s)
-------------------------------------------------
0.34            180x5        Ks    14.94 $B!^(B 0.10
1.12            300x10       Rc    17.67 $B!^(B 0.04
3.75            300x9        Rc    18.53 $B!^(B 0.02
-------------------------------------------------
```
GCN Circular #12788
SUBJECT: GRB 111228A: correction for GCN 12787
R. Itoh, K. Takaki, M. Yamanaka, M. Sasada, K. Sakimoto, M. Yoshida, K. S. Kawabata, Y. Hanabata, M. Ohno, Y. Fukazawa (HiroshimaUniv.), A. Nakashima (Tokyo Univ.) report on behalf of the Kanata collaboration:
Character corruption occurred in the table of the Kanata telescope photometric results inthe GCN circular 12787. We resubmit the corrected table. We are sorry for the inconvenience.
```
Mid time from  Total Exp  Filter  Magnitude
trigger (hr)    (s)
-------------------------------------------------
0.34           180x5       Ks    14.94 +- 0.10
1.12           300x10      Rc    17.67 +- 0.04
3.75           300x9       Rc    18.53 +- 0.02
-------------------------------------------------
```

GCN Circular #12789
V.Krushinski, I.Zalozhnich, A. Popov Ural State University, Kourovka
E. Sinykov, V.Yurkov, Yu.Sergienko, D.Varda, Blagoveschensk Educational State University, Blagoveschensk
E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, N.Tyurina, N.Shatskiy, P.Balanutsa, V.V.Chazov, A.Kuznetsov, D.Zimnukhov, M. Kornilov, A.Kuznetsov, D.Zimnukhov, M. Kornilov, A.Sankovich, S. Shurpakov Sternberg Astronomical Institute, Moscow State University
K.Ivanov, V.A.Poleshchuk, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev,E.Konstantinov, Irkutsk State University
A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory
MASTER II robotic double telescope (MASTER-Net: http://observ.pereplet.ru) located in Blagoveschensk was pointed to the GRB111228A (Ukwatta et al., GCN Circ R12737) 191 sec after notice time and 244 sec after GRB time at 2011-12-28 15:48:47.127 UT (Sinykov et al., GCN Circ 12756).
MASTER II robotic double telescope (MASTER-Net: http://observ.pereplet.ru) located near Kislovodsk was pointed to the GRB111228A ~6.5 hours after GRB time at 2011-12-28 22:24:47 UT.
The results of our photometry are:

    Date        UT       Exp  mag   Err      Filter
               Start     (s)

2011-12-28  15:48:47.1   20  16.9  0.2       P|
2011-12-28  15:48:47.1   20  16.5  0.2       P-
2011-12-28  15:49:34.7   30  17.1  0.2       P|
2011-12-28  15:49:34.7   30  16.7  0.2       P-
2011-12-28  15:50:37.3   40  16.8  0.2       P|
2011-12-28  15:50:37.3   40  17.3  0.2       P-
2011-12-28  15:51:43.1   50  17.6  0.2       P|
2011-12-28  15:51:43.1   50  17.5  0.2       P-
2011-12-28  15:52:59.7   70  16.8  0.2       P|
2011-12-28  15:52:59.7   70  17.1  0.2       P-
2011-12-28  15:54:41.3   90  17.3  0.2       P|
2011-12-28  15:54:41.3   90  17.3  0.2       P-
2011-12-28  15:56:38.4  110  17.0  0.2       P|
2011-12-28  15:56:38.4  110  17.6  0.2       P-
2011-12-28  16:01:44.8	180  17.3  0.2       P|
2011-12-28  16:01:44.8  180  17.6  0.2       P-
2011-12-28  22:24:47.9 	180  19.0  0.3       V
2011-12-28  22:24:47.9  180  18.3  0.3       R
2011-12-28  22:28:14.1	180  18.9  0.3       V
2011-12-28  22:28:14.1  180  18.8  0.3       R
2011-12-28  22:31:42.7	180  19.3  0.3       V
2011-12-28  22:31:42.7  180  18.6  0.3       R
2011-12-29  00:13:44.5  180  18.8  0.3       R
2011-12-29  00:17:12.7  180  19.4  0.3       R
2011-12-29  00:20:45.7  180  18.9  0.3       R
2011-12-29  00:20:45.7  180  19.5  0.3       V
2011-12-29  01:45:51.9  180  19.4  0.3       R
2011-12-29  01:52:48.1  180  18.7  0.3       R

P|, P- - are the 2 polarisations in white
The message may be cited.

GCN Circular #12790
S. Golenetskii, R.Aptekar, D. Frederiks, E. Mazets, V. Pal'shin, P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf of the Konus-Wind team, report:
The long GRB 111228A (Swift-BAT trigger #510649: Ukwatta et al., GCN 12737; Cummings et al., GCN 12749) triggered Konus-Wind at T0=3D56736.171s UT (15:45:36.171).
The light curve shows two groups of pulses separated by ~45 s. A total duration of the burst is ~50 s. The emission is seen up to ~1500 keV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB111228_T56736/
As observed by Konus-Wind the burst had a fluence of (7.5 =B1 1.3)x10-6 erg/cm2, and a 256-ms peak flux, measured from T0+3.584 s, of (2.0 =B1 0.3)x10-6 erg/cm2/s (both in the 20 keV - 2000 MeV energy range).
The time-integrated spectrum of the burst (measured from T0 to T0+49.408 = s) is best fit in the 20 keV - 2000 keV range by a simple power law function with the photon index of (2.4 =B1 0.2), chi2 =3D 53.7/62 dof.
The spectrum at the maximum count rate (measured from T0 to T0+8.448 s) is also best fit in the 20 keV - 2000 keV range by a simple power law function with the photon index of (2.25 =B1 0.15), chi2 =3D 77.1/62 dof.
Assuming the redshift z~0.715 (Dittman et al., GCN 12759; Cucchiara et al., GCN 12761; Palazzi et al., GCN 12765; Xu et al., GCN 12764) and a standard cosmology model with H_0 =3D 71 km/s/Mpc, Omega_M =3D 0.27, Omega_Lambda =3D 0.73, the isotropic energy release E_iso is (1.0 =B1 0.2)x10^52 erg, and the isotropic peak luminosity L_iso_max is (4.6 =B1 0.7)x10^51 erg/s.
All the quoted results are preliminary. All the quoted errors are at the 90% confidence level.
GCN Circular #12791
Yiseul Jeon, Myungshin Im, Minsung Jang (CEOU/Seoul National Univ.), and Yuji Urata (NCU) on behalf of a larger collaboration
We observed GRB 111228A (Ukwatta et al., GCN 12737) in B- and R-bands with a 1 m telescope at Mt. Lemmon, Arizona, US.
The observation started at 2011-12-30 08:03:16 UT, or 1.7 days after the BAT aleart. We detected the afterglow in the images taken with both filters. Using the the photometry calibration based on an USNO B1 star USNO-B1 1083-0199833 with B=18.85 and R=17.28 following Klotz et al. (GCN 12746), we find the following.
Filter Mid-Time[UT] Mid-Time[Since BAT] Mag B-band 2011-12-30 08:33:55 40.82 hours 21.75+-0.14 R-band 2011-12-30 10:41:29 42.95 hours 20.67+-0.09
Further observation is ongoing. We thank the LOAO operator, J. Yoon for his help with the observation.
GCN Circular #12792
S. B. Pandey, R. K. S. Yadav, Ram Sagar (ARIES, NainiTal, India) and C. S. Stalin (IIA, Bangaluru); on behalf of larger Indian GRB collaboration.
The newly installed 1.3m Devasthal Fast Optical Telescope (79.7 E, 29.4 N, altitude ~ 2450 m) started looking towards the Swift trigger 510649 (Ukwatta et al., GCN 12373) ~ 2.7 hours after the burst. The optical afterglow candidate (Ukwatta et al., GCN 12373; Xin et al., GCN 12738) was clearly detected in the individual frames with an exposure time of 120 sec each, taken in R_c band.
The decaying afterglow (Klotz et al., GCN 12742; Pandey et al., GCN 12745; Cenko et al., GCN 12771) was also detected during the observations taken on consecutive night in the frames having exposure time of 300 sec each. Preliminary photometry of the frames yields following.
```
Time (UT)                  Exp (s)     Filter      Magnitude
-------------------------------------------------------------
2011-12-28,18:30:46.0       120 s       R_c        18.1+/-0.1
2011-12-29,23:56:38.0       300 s       R_c        19.8+/-0.1
-------------------------------------------------------------
```
The magnitudes are calibrated against nearby USNO stars. Further observations are continued.
This massage may be cited.
GCN Circular #12798
V. Rumyantsev, (CrAO), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:
We observed the field of GRB 111128A (Ukwatta et al. GCN 12737) with Shajn telescope of CrAO observatory between (UT) 2011-12-28T23:08:08 and 2011-12-29T01:04:41 under a mean seeing of 1.5". We took several frames with exposure of 60 s in BVRI. The photometry optical afterglow (Ukwatta et al. GCN 12737; Xin et al. GCN 12738) is based on the USNO B1.0 star 1083-0199833 (10 00 22.70 +18 19 23.5) assuming B=18.85, R=17.28, I=17.02 .
```
      T0+        Filter, Exposure, OT,  uplim (3 sigma)
    (mid, d)            (s)

0.3476     B       27x60      19.270 +/- 0.007  23.6
0.3491     R       27x60      18.710 +/- 0.005  23.5
0.3499     I        27x60      18.608 +/- 0.006  23.2
```
GCN Circular #12809
Minsung Jang, Myungshin Im, Yiseul Jeon (CEOU/Seoul National Univ.), and Yuji Urata (NCU) on behalf of a larger collaboration
We continued our observation (Jeon et al. GCN 12791) of GRB 111228A (Ukwatta et al., GCN 12737) in R-band with a 1 m telescope at Mt. Lemmon, Arizona, US. Data were taken at 2011-12-31 UT and 2012-01-01 UT. For both of them, we detected the afterglow in stacked R-band images.
We used a USNO B1 star near the afterglow, USNO-B1 1083-0199833 with R=17.28 following Klotz et al. (GCN 12746) for our photometry calibration, and current, rough estimates are given below.
```
Mid-time [UT]           | Mid-time[Since BAT] | Exptime [sec] | R-magnitude
|
-------------------------------------------------------------------------------------------------------------


2011-12-31 08:40:25 |        64.92 hours       |    300sec X 7  | 21.5 +/-
0.28 |
2012-01-01 11:19:52 |        91.58 hours       |    300sec X 9  | 22.3 +/-
0.36 |


We thank the LOAO operator, J. Yoon for his help with these observations.
```
GCN Circular #12832
A. Volnova (SAI MSU), L. Elenin (KIAM), =A0A. Pozanenko (IKI) report on behalf of larger GRB =A0follow-up collaboration:
We observed the field of GRB 111228A (Ukwatta et al., GCN 12737) with 0.45-m telescope of ISON-NM observatory on Dec. 29 at 11:55 (UT, middle of exposure) in R band with mean FWHM of about 4.9". We took several unfiltered frames with exposure of 60 s. In a stacked image we detect an optical counterpart (Ukwatta et al., GCN 12737; Xin et al., GCN 12738). The photometry is based on the USNO-B1.0 star 1415-0025726 (RA = 10:00:22.70 Dec = +18:19:23.4, J2000) assuming R2 = 17.28:
```
T0+, =A0 =A0 =A0 =A0Filter, =A0Exposure, =A0 OT
(mid, d) =A0 =A0 =A0 =A0 =A0 =A0 (s)

0.84102 =A0 =A0R     =A01800 =A0 =A0 =A019.27+/-0.12
```
GCN Circular #12908
Paul Kuin (MSSL/UCL) and Tilan Ukwatta (MSU) reports on behalf of the Swift UVOT Team:
Until recently, Swift UVOT continued observations in multiple filters of GRB 111228A (Ukwatta et al., GCN Circ. 12737).
Based on the observations taken up to January 31, 2012 in the white filter, a possible host is detected.
The UVOT position in decimal degrees of the GRB during the early and peak emission period is: RA=150.06684 DEC=+18.297834, J2000 (sexagesimal 10:00:16.04, +18:17:52.20), consistent with the enhanced XRT position reported in GCN Circ. 12747 by Goad et al.. The position of the late time emission/possible host is: RA=150.06643 DEC=+18.297903, J2000 (sexagesimal 10:00:15.94, +18:17:52.45). The position of the late-time emission is offset by 0.9" which is significantly larger than the position error for a single uvot image of 0.5" (Breeveld et al., 2010, MNRAS 406, 1587), and the unknown smaller position error when comparing between summed UVOT images. The offset suggests that the late-time emission is due to a different source, possibly the host.
Other evidence comes from a late time flattening of the light curve.
The late time count-rate light curve decays with a power index of -1.3 in nearly all bands. Taking that as the decay rate, the light curves in white and uvw2 deviate at times more than 800ks after the trigger.
Extrapolating the power law decay and subtracting from the late-time white count rate, we estimate a host magnitude in white = 24.6 (+0.4/-0.6) mag, which corresponds to a host flux in the broadband white filter of (2.05+/-0.8)x10^-7 Jy (3471 A).

GCN Circular #12918
V.V.Golovnya (Main Astro Obs, Kyiv) report:
We have undertaken the review of the sky area in vicinity of GRB 111228� (M.R. Goad et al. GCN Circ.12747) on astronegatives, collected in Ukrainian NAS Main astronomical observatory plate archive (1976-1996). All the plates with the possible object appearance are digitized using Microtek ScanMaker 9800XL TMA and Epson Expression 10000XL flatbed scanners and have been placed into Golosiiv Plate Archive database DBGPA with open access to them.

        The list of plates is given in the table:
YYYYMMDD/TimeUT --Plates--      Exp.    LimMag  Star USNOA2
19900323/192716 GUA040C003372   14.5    15.05   1050-06177767
19920228/213449 GUA040C001967A  20.0    15.60   1050-06179692
19921201/032302 GUA040C002052A  18.0    15.05   1050-06177767
19921218/022500 GUA040C002075A  21.0    15.05   1050-06177767
19930211/220606 GUA040C002118   22.0    15.60   1050-06179692
19930314/204336 GUA040C002155   20.0    15.60   1050-06179692
Plates: ?the plates archive identifier of DWA (D/F=400/2000, 
GUA040C M=103"/mm) of the Ukrainian NAS Main Astro obs.
        (Marsden's number - 83) the plate number [1].  
Exp.   - Duration of the maximum exposure (minutes).   
LimMag - Limited V mag, derived in the 23 minutes area around
       the location given in M.R. Goad et al. GCN Circ. 12747:
       RA(J2000) = 10h 00m 16.08s, Dec(J2000) = +18d 17'52.1" 
Star USNOA2 - Comparison star.

The preview images of 6 areas together with the 23x23 min.of arc area from SkyMap can be found in http://gua.db.ukr-vo.org/img/grb/111228A/index.html The images with full resolution are available via e-mail on demand.
References:
1.L.Pakuliak DATABASE of GOLOSIIV PLATE ARCHIVE (DBGPA V2.0), http://gua.db.ukr-vo.org

GCN Report 367.1
GCN_Report 367.1 has been posted: http://gcn.gsfc.nasa.gov/reports/report_367_1.pdf by T.N. Ukwatta at MSU titled: "Final Swift Observations of GRB 111228A"
GCN Circular #13069
P. D'Avanzo, A. Melandri (INAF-OAB), E. Palazzi (INAF-IASF Bo), S. Campana (INAF-OAB), M. Della Valle (INAF-OAC), E. Pian (INAF-OATs), R. Salvaterra (INAF-IASF Mi), G. Tagliaferri (INAF-OAB) report on behalf of the CIBO collaboration:
We observed the optical counterpart of GRB 111228A (Ukwatta et al., GCN 12737) with the Italian 3.6m TNG telescope on 2012 Feb 1.16 UT (34.5 days post burst) and March 13.91 UT (76.2 days post burst). Observations were carried out in the R and I bands. The counterpart is well detected in the two epochs in both filters, with a magnitude R = 24.3 in the March observation (calibrated using Landolt standard stars). The late value is likely dominated by the host galaxy.
Differential photometry reveals that the source faded between the two epochs by 0.4 +/- 0.2 and 0.9 +/- 0.1 mag in the R and I band, respectively. The observed fading indicates that a transient component was present during our February observation. This could be due to residual afterglow emission, or to the presence of an emerging supernova (SN).
After subtracting the host galaxy flux, the color of the transient on February 1 is very red, with R-I ~ 2. This color is not typical of GRB afterglows, and is much redder than measured at early times for this object (e.g., r'-i' = 0.17 AB at t = 0.57 days: Nicuesa Guelbenzu et al., GCN 12757). Such a red spectrum, on the contrary, is consistent with that of a type-Ic SN at z=0.72 (e.g., Dittman et al., GCN 12759), since the observed R band corresponds to the rest-frame U, where severe line blanketing suppresses the SN flux. Also, the I-band magnitude of the transient is comparable to that of SN 1998bw close to the peak of luminosity, placed at z=0.72.
Although a more accurate analysis of the afterglow behaviour is necessary, based on the above arguments, we believe to have detected the emission from the SN associated with GRB 111228A.
We acknowledge the TNG staff for their support, in particular Luca Di Fabrizio and Daniele Carosati.
1512.07697 from 25 Dec 15
Li-Ping Xin et al.: Multi-Wavelength Observations of GRB 111228A and Implications for the Fireball and its environment
Observations of very early multi-wavelength afterglows are critical to reveal the properties of the radiating fireball and its environment as well as the central engine of gamma-ray bursts (GRBs). We report our optical observations of GRB 111228A from 95 sec to about 50 hours after the burst trigger and investigate its properties of the prompt gamma-rays and the ambient medium using our data and the data observed with {\em Swift} and {\em Fermi} missions. Our joint optical and X-ray spectral fits to the afterglow data show that the ambient medium features as low dust-to-gas ratio. Incorporating the energy injection effect, our best fit to the afterglow lightcurves with the standard afterglow model via the Markov Chain Monte Carlo (MCMC) technique shows that $\epsilon_e=(6.9\pm 0.3)\times 10^{-2}$, $\epsilon_B=(7.73\pm 0.62)\times 10^{-6}$, $E_{\rm K}=(6.32\pm 0.86)\times 10^{53}\rm erg$, $n=0.100\pm 0.014$ cm$^{-3}$. The low medium density likely implies that the afterglow jet may be in a halo or in a hot ISM. Achromatic shallow decay segment observed in the optical and X-ray bands is well explained with the long-lasting energy injection from the central engine, which would be a magnetar with a period of about 13 ms inferred from the data. The $E_p$ of its time-integrated prompt gamma-ray spectrum is $\sim 26$ KeV. Using the initial Lorentz factor ($\Gamma_0=476^{+225}_{-237}$) derived from our afterglow model fit, it is found that GRB 111228A satisfies the $L_{\rm iso}-E_{\rm p,z}-\Gamma_0$ relation and bridges the typical GRBs and low luminosity GRBs in this relation.

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Jochen Greiner, last update: 28-Dec-2015 [Disclaimer]