Gamma-ray Burst 141221A

(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 14 08:07:31 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     622006,   Seg_Num: 0
GRB_RA:          198.269d {+13h 13m 05s} (J2000),
                 198.457d {+13h 13m 50s} (current),
                 197.641d {+13h 10m 34s} (1950)
GRB_DEC:          +8.210d {+08d 12' 36"} (J2000),
                  +8.131d {+08d 07' 51"} (current),
                  +8.475d {+08d 28' 29"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       4725 [cnts]    Image_Peak=411 [image_cnts]
TRIGGER_DUR:     1.024 [sec] 
TRIGGER_INDEX:   146     E_range: 25-100 keV
BKG_INTEN:       19732 [cnts]
BKG_TIME:        29219.05 SOD {08:06:59.05} UT
BKG_DUR:         8 [sec]
GRB_DATE:        17012 TJD;   355 DOY;   14/12/21
GRB_TIME:        29230.95 SOD {08:07:10.95} UT
GRB_PHI:          16.63 [deg]
GRB_THETA:        26.14 [deg]
SOLN_STATUS:     0x20000003
RATE_SIGNIF:     41.19 [sigma]
IMAGE_SIGNIF:    14.98 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +2  +4  +0  +0 -23  +0 
SUN_POSTN:       269.31d {+17h 57m 15s}  -23.44d {-23d 26' 06"}
SUN_DIST:         76.02 [deg]   Sun_angle= 4.7 [hr] (West of Sun)
MOON_POSTN:      259.14d {+17h 16m 34s}  -18.61d {-18d 36' 22"}
MOON_DIST:        65.53 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:      319.08, 70.40 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      193.63, 14.74 [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 = 24.24,-17.67 [deg].  
COMMENTS:           
COMMENTS:        NOTE: This BAT event is temporally(1.0<100sec) coincident with the FERMI_GBM event (trignum=440842034).

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sun 21 Dec 14 08:07:40 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      47
TRIGGER_NUM:     440842034
GRB_RA:          213.933d {+14h 15m 44s} (J2000),
                 214.134d {+14h 16m 32s} (current),
                 213.263d {+14h 13m 03s} (1950)
GRB_DEC:         -11.117d {-11d 07' 00"} (J2000),
                 -11.186d {-11d 11' 08"} (current),
                 -10.885d {-10d 53' 04"} (1950)
GRB_ERROR:       10.82 [deg radius, statistical plus systematic]
GRB_INTEN:       142 [cnts/sec]
DATA_SIGNIF:     9.80 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        17012 TJD;   355 DOY;   14/12/21
GRB_TIME:        29231.22 SOD {08:07:11.22} UT
GRB_PHI:          59.00 [deg]
GRB_THETA:        70.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      1.16
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      65%  GRB
2nd_MOST_LIKELY:  31%  Distant Particles
DETECTORS:       0,1,1, 0,0,0, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       269.31d {+17h 57m 15s}  -23.44d {-23d 26' 06"}
SUN_DIST:         53.76 [deg]   Sun_angle= 3.7 [hr] (West of Sun)
MOON_POSTN:      259.14d {+17h 16m 34s}  -18.61d {-18d 36' 22"}
MOON_DIST:        44.01 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:      333.85, 46.63 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      215.43,  2.35 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2014/bn141221338/quicklook/glg_lc_medres34_bn141221338.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 91.83,-22.58 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(1.0<100sec) coincident with the SWIFT_BAT event (trignum=622006).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sun 21 Dec 14 08:07:50 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      57
TRIGGER_NUM:     440842034
GRB_RA:          211.920d {+14h 07m 41s} (J2000),
                 212.111d {+14h 08m 27s} (current),
                 211.282d {+14h 05m 08s} (1950)
GRB_DEC:          +0.770d {+00d 46' 12"} (J2000),
                  +0.699d {+00d 41' 58"} (current),
                  +1.007d {+01d 00' 26"} (1950)
GRB_ERROR:       6.37 [deg radius, statistical only]
DATA_SIGNIF:     13.50 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        17012 TJD;   355 DOY;   14/12/21
GRB_TIME:        29231.22 SOD {08:07:11.22} UT
GRB_PHI:          57.00 [deg]
GRB_THETA:        82.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4153 (Gnd S/W Version number)
SUN_POSTN:       269.31d {+17h 57m 15s}  -23.44d {-23d 26' 06"}
SUN_DIST:         60.52 [deg]   Sun_angle= 3.8 [hr] (West of Sun)
MOON_POSTN:      259.14d {+17h 16m 35s}  -18.61d {-18d 36' 22"}
MOON_DIST:        50.06 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:      340.86, 57.91 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      209.48, 12.86 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2014/bn141221338/quicklook/glg_lc_medres34_bn141221338.gif
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(1.0<100sec) coincident with the SWIFT_BAT event (trignum=622006).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 21 Dec 14 08:08:41 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     622006,   Seg_Num: 0
POINT_RA:        198.280d {+13h 13m 07s} (J2000)
POINT_DEC:        +8.200d {+08d 11' 59"} (J2000)
IMG_START_DATE:  17012 TJD;   355 DOY;   14/12/21
IMG_START_TIME:  29310.37 SOD {08:08:30.37} UT,   79.4 [sec] since BAT Trigger Time
COUNTS:          5    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        1    Max_iter_allowed= 4
ERROR_CODE:      1
COMMENTS:        SWIFT-XRT Nack Position.  
COMMENTS:        No source found in the image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 21 Dec 14 08:11:14 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     622006,   Seg_Num: 0
GRB_RA:          198.269d {+13h 13m 05s} (J2000),
                 198.457d {+13h 13m 50s} (current),
                 197.641d {+13h 10m 34s} (1950)
GRB_DEC:          +8.210d {+08d 12' 36"} (J2000),
                  +8.131d {+08d 07' 51"} (current),
                  +8.475d {+08d 28' 29"} (1950)
GRB_DATE:        17012 TJD;   355 DOY;   14/12/21
GRB_TIME:        29230.95 SOD {08:07:10.95} UT
TRIGGER_INDEX:   146
GRB_PHI:          16.63 [deg]
GRB_THETA:        26.14 [deg]
DELTA_TIME:      -69.00 [sec]
TRIGGER_DUR:     1.024 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     41.19 [sigma]
IMAGE_SIGNIF:    14.98 [sigma]
LC_URL:          sw00622006000msb.lc
SUN_POSTN:       269.32d {+17h 57m 16s}  -23.44d {-23d 26' 06"}
SUN_DIST:         76.02 [deg]   Sun_angle= 4.7 [hr] (West of Sun)
MOON_POSTN:      259.18d {+17h 16m 43s}  -18.61d {-18d 36' 27"}
MOON_DIST:        65.56 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:      319.08, 70.40 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      193.63, 14.74 [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 = 24.24,-17.67 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 21 Dec 14 08:13:00 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     622006,   Seg_Num: 0
POINT_RA:        198.281d {+13h 13m 07s} (J2000)
POINT_DEC:        +8.200d {+08d 12' 00"} (J2000)
POINT_ROLL:      116.687d
IMG_START_DATE:  17012 TJD;   355 DOY;   14/12/21
IMG_START_TIME:  29314.90 SOD {08:08:34.90} UT,   84.0 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        6.023
N_STARS:         19
X_OFFSET:        376 [pixels]
Y_OFFSET:        599 [pixels]
X_MAX:           1335 [pixels]
Y_MAX:           1558 [pixels]
DET_THRESH:      21
PHOTO_THRESH:    12
SL_URL:          sw00622006000msufc0083.fits
SUN_POSTN:       269.32d {+17h 57m 16s}  -23.44d {-23d 26' 06"}
SUN_DIST:         76.01 [deg]   Sun_angle= 4.7 [hr] (West of Sun)
MOON_POSTN:      259.20d {+17h 16m 48s}  -18.61d {-18d 36' 29"}
MOON_DIST:        65.57 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:      319.11, 70.39 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      193.64, 14.74 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 21 Dec 14 08:13:08 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     622006,   Seg_Num: 0
GRB_RA:          198.2878d {+13h 13m 09.07s} (J2000),
                 198.4758d {+13h 13m 54.20s} (current),
                 197.6599d {+13h 10m 38.36s} (1950)
GRB_DEC:          +8.2049d {+08d 12' 17.6"} (J2000),
                  +8.1258d {+08d 07' 32.9"} (current),
                  +8.4697d {+08d 28' 10.9"} (1950)
GRB_ERROR:       3.9 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  17012 TJD;   355 DOY;   14/12/21
IMG_START_TIME:  29333.00 SOD {08:08:53.00} UT,   102.0 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       269.32d {+17h 57m 16s}  -23.44d {-23d 26' 06"}
SUN_DIST:         76.00 [deg]   Sun_angle= 4.7 [hr] (West of Sun)
MOON_POSTN:      259.20d {+17h 16m 48s}  -18.61d {-18d 36' 29"}
MOON_DIST:        65.56 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:      319.13, 70.39 [deg] galactic lon,lat of the burst
ECL_COORDS:      193.65, 14.74 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
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:     Sun 21 Dec 14 08:13:27 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     622006,   Seg_Num: 0
POINT_RA:        198.281d {+13h 13m 07s} (J2000)
POINT_DEC:        +8.200d {+08d 12' 00"} (J2000)
POINT_ROLL:      116.687d
IMG_START_DATE:  17012 TJD;   355 DOY;   14/12/21
IMG_START_TIME:  29314.90 SOD {08:08:34.90} UT,   84.0 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        6.023
N_STARS:         19
X_OFFSET:        376 [pixels]
Y_OFFSET:        599 [pixels]
X_MAX:           1335 [pixels]
Y_MAX:           1558 [pixels]
DET_THRESH:      21
PHOTO_THRESH:    12
SL_URL:          sw00622006000msufc0083.fits
SUN_POSTN:       269.32d {+17h 57m 16s}  -23.44d {-23d 26' 06"}
SUN_DIST:         76.01 [deg]   Sun_angle= 4.7 [hr] (West of Sun)
MOON_POSTN:      259.20d {+17h 16m 49s}  -18.61d {-18d 36' 29"}
MOON_DIST:        65.57 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:      319.11, 70.39 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      193.64, 14.74 [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 14 08:14:46 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     622006,   Seg_Num: 0
POINT_RA:        198.281d {+13h 13m 07s} (J2000)
POINT_DEC:        +8.200d {+08d 12' 00"} (J2000)
ROLL:            116.687d
IMG_START_DATE:  17012 TJD;   355 DOY;   14/12/21
IMG_START_TIME:  29314.90 SOD {08:08:34.90} UT,   84.0 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     440842127
X_OFFSET:        695 [pixels]
Y_OFFSET:        918 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       855
Y_GRB_POS:       1078
BINNING_INDEX:   1
IM_URL:          sw00622006000msuni0096.fits
SUN_POSTN:       269.32d {+17h 57m 16s}  -23.44d {-23d 26' 06"}
SUN_DIST:         76.01 [deg]   Sun_angle= 4.7 [hr] (West of Sun)
MOON_POSTN:      259.22d {+17h 16m 52s}  -18.61d {-18d 36' 31"}
MOON_DIST:        65.58 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:      319.11, 70.39 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      193.64, 14.74 [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:     Sun 21 Dec 14 08:14:59 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     622006,   Seg_Num: 0
POINT_RA:        198.281d {+13h 13m 07s} (J2000)
POINT_DEC:        +8.200d {+08d 12' 00"} (J2000)
ROLL:            116.687d
IMG_START_DATE:  17012 TJD;   355 DOY;   14/12/21
IMG_START_TIME:  29314.90 SOD {08:08:34.90} UT,   84.0 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     440842127
X_OFFSET:        695 [pixels]
Y_OFFSET:        918 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       855
Y_GRB_POS:       1078
BINNING_INDEX:   1
IM_URL:          sw00622006000msuni0096.fits
SUN_POSTN:       269.32d {+17h 57m 16s}  -23.44d {-23d 26' 06"}
SUN_DIST:         76.01 [deg]   Sun_angle= 4.7 [hr] (West of Sun)
MOON_POSTN:      259.22d {+17h 16m 52s}  -18.61d {-18d 36' 31"}
MOON_DIST:        65.58 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:      319.11, 70.39 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      193.64, 14.74 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 21 Dec 14 08:16:17 UT
NOTICE_TYPE:     Swift-UVOT Position
TRIGGER_NUM:     622006,   Seg_Num: 0
GRB_RA:          198.2866d {+13h 13m 08.78s} (J2000),
                 198.4746d {+13h 13m 53.91s} (current),
                 197.6587d {+13h 10m 38.08s} (1950)
GRB_DEC:          +8.2052d {+08d 12' 18.7"} (J2000),
                  +8.1261d {+08d 07' 33.9"} (current),
                  +8.4700d {+08d 28' 12.0"} (1950)
GRB_ERROR:       0.6 [arcsec radius, statistical only]
GRB_MAG:         17.18 +/- 0.14 [mag]
FILTER:          10, White
IMG_START_DATE:  17012 TJD;   355 DOY;   14/12/21
IMG_START_TIME:  29313.00 SOD {08:08:33.00} UT,   82.0 [sec] since BAT Trigger Time
SUN_POSTN:       269.32d {+17h 57m 17s}  -23.44d {-23d 26' 06"}
SUN_DIST:         76.01 [deg]   Sun_angle= 4.7 [hr] (West of Sun)
MOON_POSTN:      259.23d {+17h 16m 56s}  -18.61d {-18d 36' 33"}
MOON_DIST:        65.59 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:      319.13, 70.39 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      193.65, 14.74 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT UVOT Position Notice.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        Result based on Genie data.  
COMMENTS:        Notice generated automatically.

GCN Circular #17206
E. Sonbas (NASA/GSFC/Adiyaman Univ.), J. R. Cummings (NASA/UMBC), V. D'Elia (ASDC), L. Izzo (URoma/ICRA), A. Y. Lien (GSFC/UMBC), K. L. Page (U Leicester), B. Sbarufatti (INAF-OAB/PSU) and M. H. Siegel (PSU) report on behalf of the Swift Team:
At 08:07:10 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 141221A (trigger=622006). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 198.269, +8.210 which is
```
   RA(J2000) = 13h 13m 05s
   Dec(J2000) = +08d 12' 36"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a double-peaked structure with a duration of about 20 sec. The peak count rate was ~4000 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 08:08:30.3 UT, 79.5 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 198.28642, 8.20536 which is equivalent to:
```
   RA(J2000)  = 13h 13m 08.74s
   Dec(J2000) = +08d 12' 19.3"
```
with an uncertainty of 3.9 arcseconds (radius, 90% containment). This location is 64 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.
A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (2.27 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 3.5 (+2.80/-2.41) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 83 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at
```
  RA(J2000)  =	13:13:08.80 = 198.28666
  DEC(J2000) = +08:12:18.8  =	8.20523
```
with a 90%-confidence error radius of about 0.61 arc sec. This position is 4.2 arc sec. from the center of the XRT error circle. The estimated magnitude is 17.18 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 E. Sonbas (edasonbas AT yahoo.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:     Sun 21 Dec 14 08:22:07 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     622006,   Seg_Num: 0
POINT_RA:        198.282d {+13h 13m 08s} (J2000)
POINT_DEC:        +8.202d {+08d 12' 08"} (J2000)
POINT_ROLL:      116.688d
IMG_START_DATE:  17012 TJD;   355 DOY;   14/12/21
IMG_START_TIME:  29527.01 SOD {08:12:07.01} UT,   296.1 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        3.047
N_STARS:         27
X_OFFSET:        136 [pixels]
Y_OFFSET:        359 [pixels]
X_MAX:           1575 [pixels]
Y_MAX:           1798 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    8
SL_URL:          sw00622006000msufc0296.fits
SUN_POSTN:       269.32d {+17h 57m 18s}  -23.44d {-23d 26' 06"}
SUN_DIST:         76.01 [deg]   Sun_angle= 4.7 [hr] (West of Sun)
MOON_POSTN:      259.29d {+17h 17m 10s}  -18.61d {-18d 36' 40"}
MOON_DIST:        65.65 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:      319.11, 70.39 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      193.64, 14.74 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 21 Dec 14 08:22:23 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     622006,   Seg_Num: 0
POINT_RA:        198.282d {+13h 13m 08s} (J2000)
POINT_DEC:        +8.202d {+08d 12' 08"} (J2000)
POINT_ROLL:      116.688d
IMG_START_DATE:  17012 TJD;   355 DOY;   14/12/21
IMG_START_TIME:  29527.01 SOD {08:12:07.01} UT,   296.1 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        3.047
N_STARS:         27
X_OFFSET:        136 [pixels]
Y_OFFSET:        359 [pixels]
X_MAX:           1575 [pixels]
Y_MAX:           1798 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    8
SL_URL:          sw00622006000msufc0296.fits
SUN_POSTN:       269.32d {+17h 57m 18s}  -23.44d {-23d 26' 06"}
SUN_DIST:         76.01 [deg]   Sun_angle= 4.7 [hr] (West of Sun)
MOON_POSTN:      259.29d {+17h 17m 11s}  -18.61d {-18d 36' 41"}
MOON_DIST:        65.65 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:      319.11, 70.39 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      193.64, 14.74 [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 14 08:22:53 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     622006,   Seg_Num: 0
GRB_RA:          198.2864d {+13h 13m 08.73s} (J2000),
                 198.4744d {+13h 13m 53.86s} (current),
                 197.6585d {+13h 10m 38.03s} (1950)
GRB_DEC:          +8.2050d {+08d 12' 18.0"} (J2000),
                  +8.1259d {+08d 07' 33.2"} (current),
                  +8.4698d {+08d 28' 11.3"} (1950)
GRB_ERROR:       2.2 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  17012 TJD;   355 DOY;   14/12/21
IMG_START_TIME:  29333.00 SOD {08:08:53.00} UT,   102.0 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       269.32d {+17h 57m 18s}  -23.44d {-23d 26' 06"}
SUN_DIST:         76.01 [deg]   Sun_angle= 4.7 [hr] (West of Sun)
MOON_POSTN:      259.30d {+17h 17m 12s}  -18.61d {-18d 36' 41"}
MOON_DIST:        65.66 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:      319.13, 70.39 [deg] galactic lon,lat of the burst
ECL_COORDS:      193.65, 14.74 [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:     Sun 21 Dec 14 08:23:46 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     622006,   Seg_Num: 0
POINT_RA:        198.282d {+13h 13m 08s} (J2000)
POINT_DEC:        +8.202d {+08d 12' 08"} (J2000)
ROLL:            116.688d
IMG_START_DATE:  17012 TJD;   355 DOY;   14/12/21
IMG_START_TIME:  29527.01 SOD {08:12:07.01} UT,   296.1 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     440842339
X_OFFSET:        695 [pixels]
Y_OFFSET:        918 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       855
Y_GRB_POS:       1078
BINNING_INDEX:   1
IM_URL:          sw00622006000msuni0309.fits
SUN_POSTN:       269.33d {+17h 57m 18s}  -23.44d {-23d 26' 06"}
SUN_DIST:         76.01 [deg]   Sun_angle= 4.7 [hr] (West of Sun)
MOON_POSTN:      259.31d {+17h 17m 14s}  -18.61d {-18d 36' 42"}
MOON_DIST:        65.67 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:      319.11, 70.39 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      193.64, 14.74 [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:     Sun 21 Dec 14 08:23:56 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     622006,   Seg_Num: 0
POINT_RA:        198.282d {+13h 13m 08s} (J2000)
POINT_DEC:        +8.202d {+08d 12' 08"} (J2000)
ROLL:            116.688d
IMG_START_DATE:  17012 TJD;   355 DOY;   14/12/21
IMG_START_TIME:  29527.01 SOD {08:12:07.01} UT,   296.1 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     440842339
X_OFFSET:        695 [pixels]
Y_OFFSET:        918 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       855
Y_GRB_POS:       1078
BINNING_INDEX:   1
IM_URL:          sw00622006000msuni0309.fits
SUN_POSTN:       269.33d {+17h 57m 18s}  -23.44d {-23d 26' 06"}
SUN_DIST:         76.01 [deg]   Sun_angle= 4.7 [hr] (West of Sun)
MOON_POSTN:      259.31d {+17h 17m 15s}  -18.61d {-18d 36' 42"}
MOON_DIST:        65.67 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:      319.11, 70.39 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      193.64, 14.74 [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 #17208
S. Covino (INAF/OAB) on behalf of the REM team:
We observed the field of the GRB141221A (Sonbas et al., GCN 17206) simultaneously in the optical and near infrared with the 60-cm robotic telescope REM at La Silla Observatory (Chile). The observations started about 1 min after the GRB, when the field was at an airmass of about 2.5 and continued for about one hour till the local twilight.
A bright source at a position consistent with the UVOT candidate afterglow is detected in all filter (grizJHK). At about 1.5 min after the GRB the afterglow was H~13.1 and faded down to H~15.8 more than 30 min later, with a decay index alpha~0.8.
GCN Circular #17209
C. Guidorzi, S. Dichiara (U. Ferrara), D. Kopac, A. Gomboc (U. Ljubljana) on behalf of a larger collaboration report:
The 1-m LCOGT McDonald telescope began observing Swift GRB 141221A (Sonbas et al. GCN 17206) on Dec 21 at 10:26:35 UT, corresponding to 2.3 hours after the burst trigger, with SDSS r' and i' filters. We detect the optical afterglow (Sonbas et al. GCN 17206; Covino GCN 17208) with i'=20.1 +- 0.3 mag at a mid time of 2.61 hours post burst (total exposure of 600 s).
GCN Circular #17210
A. Trotter, J. Haislip, D. Reichart, A. Aji, R. Beauchemin, T. Berger, A. Dow, A. Foster, N. Frank, M. Hinckle, K. Ivarsen, A. LaCluyze, M. Maples, J. Moore, M. Nysewander, C. Salemi, L. Zbinden, and J. A. Crain report:
Skynet observed the Swift BAT/XRT localization of GRB 141221A (Sonbas et al., GCN 17206, Swift trigger=622006) with two 14" telescopes of the PROMPT array at Cerro Tololo, Chile. Starting at 2014-12-21 08:07:56 UT and continuing until 08:35 UT (t=45s-28m post-trigger), Skynet took a total of 44 exposures ranging from 5s to 160s in the V and I bands. We clearly detect the optical afterglow (Covino, GCN 17208, Guidorzi et al., GCN 17209) with a rising light curve prior to t=2min, where it peaks at I=14.8.
A preliminary light curve is at:
http://www.skynet.unc.edu/grb/grb141221a.png
Magnitudes are in the Vega System, calibrated to 3 APASS stars in the field. Magnitudes have not been corrected for line-of-sight Milky Way dust extinction, with expected E(B-V)=0.024 (Schlafly & Finkbeiner 2011).
Skynet observations will continue.
GCN Circular #17211
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team.
Using 4183 s of XRT Photon Counting mode data and 6 UVOT images for GRB 141221A, 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 = 198.28686, +8.20510 which is equivalent to:
```
RA (J2000): 13h 13m 8.85s
Dec (J2000): +08d 12' 18.4"
```
with an uncertainty of 1.6 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 #17212
GRB 141221A: GROND Detection of the Optical/NIR Afterglow
T. Schweyer, P. Wiseman, P. Schady and J. Greiner (all MPE Garching), report on behalf of the GROND team:
We observed the field of GRB 141221A (Swift trigger 622006; Sonbas et al., GCN #17206) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla Observatory (Chile).
Observations started at 08:09:33 UT on 21/12/2014, 142 seconds after the GRB trigger, and continued in all bands for ~18 minutes of exposures until the beginning of twilight, and in NIR for another 4 minute exposure. They were performed at an average seeing of 1.7" and at an average airmass of 2.1.
We find a single point source, consistent with the enhanced SWIFT-XRT position of Beardmore et al. (GCN #17211) and that reported by e.g. Covino (GCN 17208), Trotter et al. (GCN #17210), at:
RA (J2000.0) = 13h 13m 08.80s
DEC (J2000.0) = + 08d 12' 18.9"
with an uncertainty of 0.2" in both co-ordinates.
There were problems with telescope pointing throughout the observations, Based on our first short exposures in grizJHK, we estimate preliminary magnitudes (all in AB system) of
```
g' = 17.1 +/- 0.1 mag,
r' = 16.6 +/- 0.1 mag,
i' = 16.4 +/- 0.1 mag,
z' = 16.1 +/- 0.1 mag,
J = 15.7 +/- 0.1 mag,
H = 15.4 +/- 0.1 mag, and
K = 15.3 +/- 0.1 mag.
```
The best-fit SED has a spectral index beta = 1.0 +/- 0.1.
Given magnitudes are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.024 mag in the direction of the burst (Schlegel et al. 1998).
GCN Circular #17213
T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), E. Sonbas (NASA/GSFC/Adiyaman Univ.), M. Stamatikos (OSU), J. Tueller (GSFC) (i.e. the Swift-BAT team):
Using the data set from T-61 to T+242 sec from recent telemetry downlinks, we report further analysis of BAT GRB 141221A (trigger #622006) (Sonbas, et al., GCN Circ. 17206). The BAT ground-calculated position is RA, Dec = 198.283, 8.197 deg, which is
```
   RA(J2000)  =  13h 13m 07.9s 
   Dec(J2000) = +08d 11' 49.8" 
```
with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 78%.
The mask-weighted light curve shows some low-level precursor emission starting at ~T-23 sec with the first peak starting at ~T-3 sec, peaking at ~T+1 sec, and the second peak peaking at ~T+14 sec, and ending at T+35 sec. T90 (15-350 keV) is 36.9 +- 4.0 sec (estimated error including systematics).
The time-averaged spectrum from T-24.11 to T+20.33 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.74 +- 0.08. The fluence in the 15-150 keV band is 2.1 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T-0.10 sec in the 15-150 keV band is 3.1 +- 0.2 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/622006/BA/
GCN Circular #17214
A. Maselli (INAF-IASFPA), A. Melandri (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), J.A. Kennea (PSU), V. Mangano (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), C. Pagani (U. Leicester) and E. Sonbas report on behalf of the Swift-XRT team:
We have analysed 8.9 ks of XRT data for GRB 141221A (Sonbas et al. GCN Circ. 17206), from 64 s to 34.9 ks after the BAT trigger. The data comprise 48 s in Windowed Timing (WT) mode (the first 8 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN Circ. 17211).
The late-time light curve (from T0+3.9 ks) can be modelled with a power-law decay with a decay index of alpha=1.26 (+0.17, -0.16).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.26 (+0.21, -0.20). The best-fitting absorption column is 3.1 (+0.8, -0.7) x 10^21 cm^-2, in excess of the Galactic value of 2.3 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.3 x 10^-11 (5.6 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     3.1 (+0.8, -0.7) x 10^21 cm^-2
Galactic foreground: 2.3 x 10^20 cm^-2
Excess significance: 6.7 sigma
Photon index:	     2.26 (+0.21, -0.20)
```
If the light curve continues to decay with a power-law decay index of 1.26, the count rate at T+24 hours will be 3.5 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.1 x 10^-13 (2.0 x 10^-13) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00622006.
This circular is an official product of the Swift-XRT team.
GCN Circular #17216
H.-F. Yu (MPE) reports on behalf of the Fermi GBM Team:
"At 08:07:11.22 UT on 21 Dec 2014, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 141221A (trigger 440842034 / 141221338), which was also detected by Swift (Sonbas et al. 2014, GCN 17206). The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight is about 76 degrees.
The GBM light curve consists of two pulses with a duration (T90) of about 23.8 s (50-300 keV). The time-averaged spectrum from T0-1.024 s to T0+17.408 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.07 +/- 0.13 and the cutoff energy, parameterized as Epeak, is 152.4 +/- 28.5 keV.
The event fluence (8-1000 keV) in this time interval is (3.4 +/- 0.4)E-06 erg/cm^2. The 1.024-sec peak photon flux measured starting from T0-0.192 s in the 8-1000 keV band is 5.4 +/- 0.3 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN Circular #17219
F. E. Marshall (NASA/GSFC) and E. Sonbas (NASA/GSFC/Adiyaman Univ.) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 141221A 84 s after the BAT trigger (Sonbas et al., GCN Circ. 17206). A source consistent with the enhanced XRT position (Beardmore et al. GCN Circ. 17211) is detected in the initial UVOT exposures.
The preliminary UVOT position is:
```
    RA  (J2000) =3D  13:13:08.81 =3D 198.28672 (deg.)
    Dec (J2000) =3D +08:12:18.8  =3D   8.20522 (deg.)
```
with an estimated uncertainty of 0.43 arc sec. (radius, 90% confidence).
Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white               84          234          147         17.33 =B1 0.04
v                  626          646           19         17.43 =B1 0.26
b                  552          571           20         17.92 =B1 0.21
u                  296          546          246         17.62 =B1 0.07
w1                4061         4261          197        >20.0
m2                3856        10742          414        >20.9
w2                6231         6399          165        >20.5
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) =3D 0.03 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #17221
A. Trotter, J. Haislip, D. Reichart, A. Aji, R. Beauchemin, T. Berger, A. Dow, A. Foster, N. Frank, M. Hinckle, K. Ivarsen, A. LaCluyze, M. Maples, J. Moore, M. Nysewander, C. Salemi, L. Zbinden, and J. A. Crain report:
Skynet continued to observe the Swift UVOT localization of GRB 141221A (Sonbas et al., GCN 17206, Swift trigger=622006) with two 16" telescopes of the PROMPT array at Cerro Tololo, Chile. Starting at 2014-12-22 07:08 UT and continuing until 08:34 UT (t=23.0h-24.5h post-trigger), Skynet took a total of 64 exposures of 160s each in the V and I bands. We stacked subsets of these images to maximize the signal-to-noise ratio. We no longer detect the optical afterglow that we described in Trotter et al. (GCN 17210).
Our limiting magnitudes are:
```
==================================
tmid  expos  fil  limit
==================================
23.8h 32x160s V   >21.2
23.8h 31x160s I   >20.7
```
A preliminary light curve is at:
http://www.skynet.unc.edu/grb/grb141221a_2.png
Magnitudes are in the Vega System, calibrated to 3 APASS stars in the field. Magnitudes have not been corrected for line-of-sight Milky Way dust extinction, with expected E(B-V)=0.024 (Schlafly & Finkbeiner 2011).
No further Skynet observations are scheduled.
GCN Circular #17222
Y. Ono, T. Yoshii, Y. Saito, Y. Tachibana, H. Ohuchi, Y. Yano, S. Kurita, T. Fujiwara, Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration:
We observed the field of GRB 141221A (E .Sonbas et al., GCN Circular #17206) with the optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan.
The observation started on 2014-12-21 17:20:13 UT (~9.1 h after the burst). We did not find any new point source within the refined XRT error circle (A.P. Beardmore., GCN Circular #17211) in all the three bands.
The measured magnitudes are listed below.
```
T0+[sec]     MID-UT    T-EXP[sec]        g'         Rc        Ic
-----------------------------------------------------------------------------
33183        18:51:55        9600          >21.3   >20.8   >20.2
-----------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
We used GSC2.3 catalog for flux calibration.
```
GCN Circular #17227
Klotz A., Turpin D. (IRAP-CNRS-OMP), Boer M., Gendre B., Siellez K., Dereli H., Bardho O. (UNS-CNRS-OCA), Atteia J.L. (IRAP-CNRS-OMP) report:
We imaged the field of GRB 141221A detected by SWIFT (trigger 622006) with the TAROT robotic telescope (D=25cm) located at the European Southern Observatory, La Silla observatory, Chile.
The observations started 31.2s after the GRB trigger (14.2s after the notice). The elevation of the field increased from 23 degrees above horizon and weather conditions were good but the dawn interrupted the observations after 41 minutes.
The first image is trailed with a duration of 60.0s (see the description in Klotz et al., 2006, A&A 451, L39). We do not detect the optical counterpart between 31s and 68s at a limiting magnitude Rlim = 16.6. Then the end of the trail shows a sudden appearance of the optical counterpart (cf. Sonbas et al. GCNC 17206). Measures are:
```
  start    end  magnitude
  (sec)  (sec)
   31.2   68.5  Rlim = 16.6
   68.5   74.5  R = 16.0 +/- 0.2
   74.5   80.5  R = 15.7 +/- 0.2
   80.5   86.5  R = 15.5 +/- 0.2
   86.5   92.5  R = 15.6 +/- 0.3
```
Next images (in tracking mode) show the optical transcient:
```
  start    end  magnitude
  (sec)  (sec)  R    +/-
  104.6  134.6 15.47 0.03
  145.1  175.1 15.36 0.03
  185.7  215.7 15.40 0.03
  226.0  256.0 15.42 0.03
  266.3  296.3 15.39 0.03
  306.7  396.7 15.60 0.09
  401.3  491.3 16.17 0.02
  715.6  805.6 16.63 0.02
  816.2  906.2 16.68 0.08
 1029.4 1119.4 16.95 0.08
 1130   1525   17.22 0.08
 1536   2486   17.82 0.08
```
The early afterglow observed by TAROT is compatible with that observed by PROMPT (Trotter et al. GCNC 17210 and GCNC 17221).
Magnitudes were estimated with the nearby star NOMAD-1 0982-0272573 R=12.23 and are not corrected for galactic dust extinction.
GCN Circular #17228
D. A. Perley, Y. Cao (Caltech), and S. B. Cenko (GSFC) report:
We observed the optical afterglow of GRB 141221A (Sonbas et al., GCN 17206) with the DEIMOS spectrograph on the Keck II telescope between 12:48 and 13:10 UT on 2014-12-21. Two 900-second exposures were acquired at high airmass.
We detect significant continuum flux across the entire spectral range between 4490-9660 Angstroms. Inspection of the 1D spectrum shows two apparent absorption features at 6854 and 6873 Angstroms which we tentatively associate with the Mg II doublet at z=1.452. Lower-significance probable absorption lines are also seen at the wavelengths of the Fe II 2599, 2585, 2383, 2374, and 2344 lines at similar redshift, lending additional credence to this association. However, due to a failure of the blue arc calibration lamps, we note that our wavelength solution is preliminary and this result should be considered tentative.
1602.09014 from 1 Mar 16
O. Bardho et al.: GRB 141221A: gone is the wind
GRB 141221A was observed from infrared to soft gamma-ray bands. Here, we investigate its properties, in light of the standard model. We find that the optical light curve of the afterglow of this burst presents an unusual steep/quick rise. The broad band spectral energy distribution taken near the maximum of the optical emission presents either a thermal component or a spectral break. In the former case, the properties of the afterglow are then very unusual, but could explain the lack of apparent jet breaks in the Swift light curves. In the latter case, the afterglow properties of this burst are more usual, and we can see in the light curves the passing through of the injection and cooling frequencies within the optical bands, not masked by a reverse shock. This model also excludes the presence of a stellar wind, challenging either the stellar progenitor properties, or the very stellar nature of the progenitor itself. In all cases, this burst may be a part of a Rosetta stone that could help to explain some of the most striking features discovered by Swift during the last ten years.

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Jochen Greiner, last update: 01-Mar-2016 [Disclaimer]