Gamma-ray Burst 170126A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

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Results of Observations

GCN/BACODINE POSITION NOTICE

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 26 Jan 17 11:30:57 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     735188,   Seg_Num: 0
GRB_RA:          263.579d {+17h 34m 19s} (J2000),
                 263.998d {+17h 36m 00s} (current),
                 262.353d {+17h 29m 25s} (1950)
GRB_DEC:         -64.757d {-64d 45' 26"} (J2000),
                 -64.768d {-64d 46' 03"} (current),
                 -64.723d {-64d 43' 23"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       4204 [cnts]    Image_Peak=92 [image_cnts]
TRIGGER_DUR:     1.024 [sec] 
TRIGGER_INDEX:   155     E_range: 50-350 keV
BKG_INTEN:       18182 [cnts]
BKG_TIME:        41429.48 SOD {11:30:29.48} UT
BKG_DUR:         8 [sec]
GRB_DATE:        17779 TJD;    26 DOY;   17/01/26
GRB_TIME:        41442.28 SOD {11:30:42.28} UT
GRB_PHI:         -90.17 [deg]
GRB_THETA:        40.89 [deg]
SOLN_STATUS:     0x20000003
RATE_SIGNIF:     36.52 [sigma]
IMAGE_SIGNIF:    7.35 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +3  -3  +0  +0 -57  +0 
SUN_POSTN:       309.10d {+20h 36m 23s}  -18.59d {-18d 35' 39"}
SUN_DIST:         55.00 [deg]   Sun_angle= 3.0 [hr] (West of Sun)
MOON_POSTN:      289.96d {+19h 19m 50s}  -18.41d {-18d 24' 47"}
MOON_DIST:        49.51 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      327.78,-16.69 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      266.35,-41.40 [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 = 283.46,1.17 [deg].  
COMMENTS:           
COMMENTS:        NOTE: This BAT event is temporally(1.0<100sec) coincident with the FERMI_GBM event (trignum=507123046).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 26 Jan 17 11:31:14 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      58
TRIGGER_NUM:     507123046
GRB_RA:          259.750d {+17h 19m 00s} (J2000),
                 260.123d {+17h 20m 29s} (current),
                 258.660d {+17h 14m 38s} (1950)
GRB_DEC:         -58.717d {-58d 43' 00"} (J2000),
                 -58.733d {-58d 43' 59"} (current),
                 -58.665d {-58d 39' 51"} (1950)
GRB_ERROR:       5.13 [deg radius, statistical plus systematic]
GRB_INTEN:       503 [cnts/sec]
DATA_SIGNIF:     43.30 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        17779 TJD;    26 DOY;   17/01/26
GRB_TIME:        41441.54 SOD {11:30:41.54} UT
GRB_PHI:         144.00 [deg]
GRB_THETA:        45.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      0.92
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      97%  GRB
2nd_MOST_LIKELY:   1%  Generic Transient
DETECTORS:       0,0,0, 0,0,0, 1,0,0, 1,0,1, 0,0,
SUN_POSTN:       309.10d {+20h 36m 23s}  -18.59d {-18d 35' 39"}
SUN_DIST:         53.46 [deg]   Sun_angle= 3.3 [hr] (West of Sun)
MOON_POSTN:      289.96d {+19h 19m 51s}  -18.41d {-18d 24' 46"}
MOON_DIST:        45.80 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      332.16,-12.02 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      263.48,-35.51 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2017/bn170126480/quicklook/glg_lc_medres34_bn170126480.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 354.97,18.87 [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=735188).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 26 Jan 17 11:31:18 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      57
TRIGGER_NUM:     507123046
GRB_RA:          261.780d {+17h 27m 07s} (J2000),
                 262.230d {+17h 28m 55s} (current),
                 260.463d {+17h 21m 51s} (1950)
GRB_DEC:         -67.880d {-67d 52' 47"} (J2000),
                 -67.893d {-67d 53' 35"} (current),
                 -67.837d {-67d 50' 12"} (1950)
GRB_ERROR:       1.88 [deg radius, statistical only]
DATA_SIGNIF:     55.50 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        17779 TJD;    26 DOY;   17/01/26
GRB_TIME:        41441.54 SOD {11:30:41.54} UT
GRB_PHI:         156.00 [deg]
GRB_THETA:        48.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4153 (Gnd S/W Version number)
SUN_POSTN:       309.10d {+20h 36m 23s}  -18.59d {-18d 35' 39"}
SUN_DIST:         57.36 [deg]   Sun_angle= 3.1 [hr] (West of Sun)
MOON_POSTN:      289.96d {+19h 19m 51s}  -18.41d {-18d 24' 46"}
MOON_DIST:        52.50 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      324.56,-17.57 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      265.67,-44.56 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2017/bn170126480/quicklook/glg_lc_medres34_bn170126480.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_507123046.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        In the LAT Field-of-view.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file will not be created/available until ~15 min after the trigger.  
COMMENTS:        The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(1.0<100sec) coincident with the SWIFT_BAT event (trignum=735188).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 26 Jan 17 11:31:05 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      45
TRIGGER_NUM:     507123046
GRB_RA:          240.600d {+16h 02m 24s} (J2000),
                 240.992d {+16h 03m 58s} (current),
                 239.458d {+15h 57m 50s} (1950)
GRB_DEC:         -64.367d {-64d 22' 00"} (J2000),
                 -64.413d {-64d 24' 46"} (current),
                 -64.228d {-64d 13' 38"} (1950)
GRB_ERROR:       7.25 [deg radius, statistical plus systematic]
GRB_INTEN:       465 [cnts/sec]
DATA_SIGNIF:     21.60 [sigma]
INTEG_TIME:      1.024 [sec]
GRB_DATE:        17779 TJD;    26 DOY;   17/01/26
GRB_TIME:        41441.54 SOD {11:30:41.54} UT
GRB_PHI:         149.00 [deg]
GRB_THETA:        55.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO:      0.83
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      97%  GRB
2nd_MOST_LIKELY:   1%  Generic Transient
DETECTORS:       0,0,0, 0,0,0, 1,0,0, 1,0,1, 0,0,
SUN_POSTN:       309.10d {+20h 36m 23s}  -18.59d {-18d 35' 39"}
SUN_DIST:         63.88 [deg]   Sun_angle= 4.5 [hr] (West of Sun)
MOON_POSTN:      289.96d {+19h 19m 51s}  -18.41d {-18d 24' 46"}
MOON_DIST:        56.37 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      321.83, -8.75 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      253.22,-42.63 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2017/bn170126480/quicklook/glg_lc_medres34_bn170126480.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 354.97,18.87 [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=735188).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 26 Jan 17 11:32:19 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     735188,   Seg_Num: 0
POINT_RA:        263.553d {+17h 34m 13s} (J2000)
POINT_DEC:       -64.769d {-64d 46' 06"} (J2000)
IMG_START_DATE:  17779 TJD;    26 DOY;   17/01/26
IMG_START_TIME:  41529.40 SOD {11:32:09.40} UT,   87.1 [sec] since BAT Trigger Time
COUNTS:          7    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        1    Max_iter_allowed= 4
ERROR_CODE:      1
COMMENTS:        SWIFT-XRT Nack Position.  
COMMENTS:        No source found in the image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 26 Jan 17 11:34:55 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     735188,   Seg_Num: 0
GRB_RA:          263.579d {+17h 34m 19s} (J2000),
                 263.998d {+17h 36m 00s} (current),
                 262.353d {+17h 29m 25s} (1950)
GRB_DEC:         -64.757d {-64d 45' 26"} (J2000),
                 -64.768d {-64d 46' 03"} (current),
                 -64.723d {-64d 43' 23"} (1950)
GRB_DATE:        17779 TJD;    26 DOY;   17/01/26
GRB_TIME:        41442.28 SOD {11:30:42.28} UT
TRIGGER_INDEX:   155
GRB_PHI:         -90.17 [deg]
GRB_THETA:        40.89 [deg]
DELTA_TIME:      0.00 [sec]
TRIGGER_DUR:     1.024 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     36.52 [sigma]
IMAGE_SIGNIF:    7.35 [sigma]
LC_URL:          sw00735188000msb.lc
SUN_POSTN:       309.10d {+20h 36m 24s}  -18.59d {-18d 35' 36"}
SUN_DIST:         55.00 [deg]   Sun_angle= 3.0 [hr] (West of Sun)
MOON_POSTN:      290.00d {+19h 19m 59s}  -18.41d {-18d 24' 38"}
MOON_DIST:        49.52 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      327.78,-16.69 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      266.35,-41.40 [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 = 283.46,1.17 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 26 Jan 17 11:35:43 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     735188,   Seg_Num: 0
POINT_RA:        263.554d {+17h 34m 13s} (J2000)
POINT_DEC:       -64.768d {-64d 46' 05"} (J2000)
POINT_ROLL:      55.528d
IMG_START_DATE:  17779 TJD;    26 DOY;   17/01/26
IMG_START_TIME:  41532.61 SOD {11:32:12.61} UT,   90.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.344
N_STARS:         190
X_OFFSET:        583 [pixels]
Y_OFFSET:        472 [pixels]
X_MAX:           1542 [pixels]
Y_MAX:           1431 [pixels]
DET_THRESH:      17
PHOTO_THRESH:    10
SL_URL:          sw00735188000msufc0090.fits
SUN_POSTN:       309.10d {+20h 36m 24s}  -18.59d {-18d 35' 36"}
SUN_DIST:         55.01 [deg]   Sun_angle= 3.0 [hr] (West of Sun)
MOON_POSTN:      290.00d {+19h 20m 01s}  -18.41d {-18d 24' 36"}
MOON_DIST:        49.53 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      327.77,-16.68 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      266.34,-41.41 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 26 Jan 17 11:36:16 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     735188,   Seg_Num: 0
POINT_RA:        263.554d {+17h 34m 13s} (J2000)
POINT_DEC:       -64.768d {-64d 46' 05"} (J2000)
POINT_ROLL:      55.528d
IMG_START_DATE:  17779 TJD;    26 DOY;   17/01/26
IMG_START_TIME:  41532.61 SOD {11:32:12.61} UT,   90.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.344
N_STARS:         190
X_OFFSET:        583 [pixels]
Y_OFFSET:        472 [pixels]
X_MAX:           1542 [pixels]
Y_MAX:           1431 [pixels]
DET_THRESH:      17
PHOTO_THRESH:    10
SL_URL:          sw00735188000msufc0090.fits
SUN_POSTN:       309.10d {+20h 36m 24s}  -18.59d {-18d 35' 36"}
SUN_DIST:         55.01 [deg]   Sun_angle= 3.0 [hr] (West of Sun)
MOON_POSTN:      290.01d {+19h 20m 02s}  -18.41d {-18d 24' 35"}
MOON_DIST:        49.53 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      327.77,-16.68 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      266.34,-41.41 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 26 Jan 17 11:37:16 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     735188,   Seg_Num: 0
GRB_RA:          263.6334d {+17h 34m 32.01s} (J2000),
                 264.0526d {+17h 36m 12.62s} (current),
                 262.4071d {+17h 29m 37.71s} (1950)
GRB_DEC:         -64.7604d {-64d 45' 37.4"} (J2000),
                 -64.7706d {-64d 46' 14.1"} (current),
                 -64.7266d {-64d 43' 35.6"} (1950)
GRB_ERROR:       4.2 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  17779 TJD;    26 DOY;   17/01/26
IMG_START_TIME:  41602.00 SOD {11:33:22.00} UT,   159.7 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       309.10d {+20h 36m 25s}  -18.59d {-18d 35' 35"}
SUN_DIST:         54.98 [deg]   Sun_angle= 3.0 [hr] (West of Sun)
MOON_POSTN:      290.02d {+19h 20m 04s}  -18.41d {-18d 24' 32"}
MOON_DIST:        49.51 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      327.79,-16.71 [deg] galactic lon,lat of the burst
ECL_COORDS:      266.39,-41.40 [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 0.11% < P(seren) < 0.58%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 26 Jan 17 11:37:37 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     735188,   Seg_Num: 0
POINT_RA:        263.554d {+17h 34m 13s} (J2000)
POINT_DEC:       -64.768d {-64d 46' 05"} (J2000)
ROLL:            55.528d
IMG_START_DATE:  17779 TJD;    26 DOY;   17/01/26
IMG_START_TIME:  41532.61 SOD {11:32:12.61} UT,   90.3 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     507123151
X_OFFSET:        902 [pixels]
Y_OFFSET:        791 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1062
Y_GRB_POS:       951
BINNING_INDEX:   1
IM_URL:          sw00735188000msuni0109.fits
SUN_POSTN:       309.10d {+20h 36m 25s}  -18.59d {-18d 35' 35"}
SUN_DIST:         55.01 [deg]   Sun_angle= 3.0 [hr] (West of Sun)
MOON_POSTN:      290.02d {+19h 20m 05s}  -18.41d {-18d 24' 31"}
MOON_DIST:        49.54 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      327.77,-16.68 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      266.34,-41.41 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 26 Jan 17 11:37:57 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     735188,   Seg_Num: 0
POINT_RA:        263.554d {+17h 34m 13s} (J2000)
POINT_DEC:       -64.768d {-64d 46' 05"} (J2000)
ROLL:            55.528d
IMG_START_DATE:  17779 TJD;    26 DOY;   17/01/26
IMG_START_TIME:  41532.61 SOD {11:32:12.61} UT,   90.3 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     507123151
X_OFFSET:        902 [pixels]
Y_OFFSET:        791 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1062
Y_GRB_POS:       951
BINNING_INDEX:   1
IM_URL:          sw00735188000msuni0109.fits
SUN_POSTN:       309.10d {+20h 36m 25s}  -18.59d {-18d 35' 35"}
SUN_DIST:         55.01 [deg]   Sun_angle= 3.0 [hr] (West of Sun)
MOON_POSTN:      290.02d {+19h 20m 06s}  -18.41d {-18d 24' 31"}
MOON_DIST:        49.54 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      327.77,-16.68 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      266.34,-41.41 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 26 Jan 17 11:39:18 UT
NOTICE_TYPE:     Swift-UVOT Position
TRIGGER_NUM:     735188,   Seg_Num: 0
GRB_RA:          263.6331d {+17h 34m 31.94s} (J2000),
                 264.0523d {+17h 36m 12.55s} (current),
                 262.4068d {+17h 29m 37.63s} (1950)
GRB_DEC:         -64.7602d {-64d 45' 36.7"} (J2000),
                 -64.7704d {-64d 46' 13.4"} (current),
                 -64.7264d {-64d 43' 34.9"} (1950)
GRB_ERROR:       0.6 [arcsec radius, statistical only]
GRB_MAG:         18.12 +/- 0.14 [mag]
FILTER:          10, White
IMG_START_DATE:  17779 TJD;    26 DOY;   17/01/26
IMG_START_TIME:  41529.00 SOD {11:32:09.00} UT,   86.7 [sec] since BAT Trigger Time
SUN_POSTN:       309.10d {+20h 36m 25s}  -18.59d {-18d 35' 34"}
SUN_DIST:         54.98 [deg]   Sun_angle= 3.0 [hr] (West of Sun)
MOON_POSTN:      290.04d {+19h 20m 09s}  -18.41d {-18d 24' 28"}
MOON_DIST:        49.52 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      327.79,-16.71 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      266.39,-41.40 [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 #20530
D. Kocevski (NASA/MSFC), S. D. Barthelmy (GSFC), A. A. Breeveld (UCL-MSSL), D. N. Burrows (PSU), A. D'Ai (INAF-IASFPA), S. W. K Emery (UCL-MSSL), J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC) and M. H. Siegel (PSU) report on behalf of the Swift Team:
At 11:30:42 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 170126A (trigger=735188). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 263.579, -64.757 which is
```
   RA(J2000)  =  17h 34m 19s
   Dec(J2000) = -64d 45' 26"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a single FRED-like peak structure with a duration of about 15 sec. The peak count rate was ~3000 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 11:32:09.4 UT, 87.1 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 263.63341, -64.76046 which is equivalent to:
```
   RA(J2000)  = 17h 34m 32.02s
   Dec(J2000) = -64d 45' 37.7"
```
with an uncertainty of 4.2 arcseconds (radius, 90% containment). This location is 84 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. No spectrum from the promptly downlinked event data is yet available to determine the column density.
UVOT took a finding chart exposure of 131 seconds with the White filter starting 90 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at
```
  RA(J2000)  =	17:34:31.95 = 263.63311
  DEC(J2000) = -64:45:37.0  = -64.76027
```
with a 90%-confidence error radius of about 0.62 arc sec. This position is 0.9 arc sec. from the center of the XRT error circle. The estimated magnitude is 18.12 with a 1-sigma error of about 0.15. No correction has been made for the expected extinction corresponding to E(B-V) of 0.10.
Burst Advocate for this burst is D. Kocevski (dankocevski AT gmail.com). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.)
GCN Circular #20531
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team.
Using 2613 s of XRT Photon Counting mode data and 2 UVOT images for GRB 170126A, 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 = 263.63308, -64.76064 which is equivalent to:
```
RA (J2000): 17h 34m 31.94s
Dec (J2000): -64d 45' 38.3"
```
with an uncertainty of 1.9 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 #20533
E. Bissaldi (Politecnico & INFN Bari) reports on behalf of the Fermi GBM Team:
"At 11:30:41.54 UT on 26 January 2017, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 170126A (trigger 507123046 / 170126480), which was also detected by the Swift/BAT (Kocevski et al. 2017, GCN 20530). The GBM on-ground location is consistent with the Swift position.
The trigger resulted in an Autonomous Repoint Request (ARR) by the GBM Flight Software owing to the high peak flux of the GRB. This ARR was accepted and the spacecraft slewed to the GBM in-flight location. The initial angle from the Fermi-LAT boresight to the BAT location is 46 degrees.
The GBM light curve consists of a single peak with a duration (T90) of about 14 s (50-300 keV). The time-averaged spectrum from T0 to T0+14 s is adequately fit by a power law function with an exponential high-energy cutoff. The power law index is -1.13 +/- 0.04 and the cutoff energy, parameterized as Epeak, is 260 +/- 21 keV. A Band function fits the spectrum equally well with Epeak = 187 +/- 23 keV, alpha = -1.02 +/- 0.06 and beta = -2.08 +/- 0.11.
The event fluence (10-1000 keV) in this time interval is (9.5 +/- 0.3)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+1 s in the 10-1000 keV band is 12.3 +/- 0.4 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN Circular #20534
F. E. Marshall (NASA/GSFC) and D. Kocevski (NASA/MSFC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 170126A 91 s after the BAT trigger (Kocevski et al., GCN Circ. 20530). A fading source consistent with the enhanced XRT position (Beardmore et al. GCN Circ. 20531) is detected in the initial UVOT exposure.
The preliminary UVOT position is:
```
    RA  (J2000) =  17:34:31.97 = 263.63319 (deg.)
    Dec (J2000) = -64:45:37.3  = -64.76035 (deg.)
```
with an estimated uncertainty of 0.45 arc sec. (radius, 90% confidence).
Preliminary detection 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 91 222 129 18.10 +/- 0.05 white 11432 12036 590 >19.7 v 1907 2273 58 >17.7 b 1832 6164 132 >20.1 u 1807 6084 255 >19.3 w1 1783 5879 255 >19.8 m2 1931 2297 58 >20.0 w2 1882 2248 58 >19.4 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.10 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #20535
D.N. Burrows (PSU), P.A. Evans (U. Leicester), S.L. Gibson (U. Leicester), J.P. Osborne (U. Leicester), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. Cholden-Brown (PSU), S. J. LaPorte (PSU) and report on behalf of the Swift-XRT team: report on behalf of the Swift-XRT team:
We have analysed 7.0 ks of XRT data for GRB 170126A, from 73 s to 40.7 ks after the BAT trigger. The data comprise 68 s in Windowed Timing (WT) mode (the first 7 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode.
The light curve can be modelled with a power-law decay with a decay index of alpha=1.30 (+0.06, -0.05).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.52 (+0.33, -0.28). The best-fitting absorption column is 2.0 (+2.5, -1.3) x 10^21 cm^-2, consistent with the Galactic value of 7.0 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 4.5 x 10^-11 (5.3 x 10^-11) erg cm^-2 count^-1.
A summary of the WT-mode spectrum is thus:
```
Total column:	     2.0 (+2.5, -1.3) x 10^21 cm^-2
Galactic foreground: 7.0 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.52 (+0.33, -0.28)
```
If the light curve continues to decay with a power-law decay index of 1.30, the count rate at T+24 hours will be 9.2 x 10^-4 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.2 x 10^-14 (4.9 x 10^-14) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00735188.
This circular is an official product of the Swift-XRT team.
GCN Circular #20537
V. Sharma, D. Bhattacharya and V. Bhalerao (IUCAA), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:
Analysis of AstroSat CZTI data showed clear detection of GRB170126A (Swift detection: D. Kocevski et al., GCN Circ. 20530) in quadrant C and D in the 40-200 keV energy range. The light curve shows single peak structure with main peak at 11:30:42 UT, coincident with Swift trigger. The measured peak count rate is 185.7 counts/sec above the background in combined data of four quadrants, with a total 1008.2 counts. The local mean background count rate was 336.3 counts/sec. Using cumulative rates, we measure a T90 of 26.9 secs.
It was clearly detected in the CsI anticoincidence detector (Veto) also as bright detection in the 100-500 keV energy range.
CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.
GCN Circular #20547
A.Kozlova, S. Golenetskii, R. Aptekar, D. Frederiks, P. Oleynik, M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline on behalf of the Konus-Wind team, report:
The long-duration GRB 170126A (Swift-BAT detection: Kocevski et al., GCN 20530; Fermi-GBM observation: Bissaldi, GCN 20533; AstroSat CZTI detection: Sharma et al., GCN 20537) triggered Konus-Wind at T0=41440.253 s UT (11:30:40.253).
The burst light curve shows a single pulse started at ~T0-0.5 s with a total duration of ~28 s. The emission is seen up to 2 MeV.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB170126_T41440/
As observed by Konus-Wind, the burst had a fluence of 8.25(-0.81,+0.94)x10^-6 erg/cm2, and a 64-ms peak flux, measured from T0+0.992 s, of 2.87(-0.85,+0.87)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst (measured from T0 to T0+16.640 s) is best fit in the 20 keV - 2 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.98(-0.22,+0.24) and Ep = 188(-27,+40) keV (chi2 = 54/59 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.8 (chi2 = 54/58 dof)
The spectrum near the maximum count rate (measured from T0+0.256 to T0+8.448 s) is best fit in the 20 keV - 2 MeV range by a power law with exponential cutoff model with alpha = -1.03(-0.17,+0.18) and Ep = 206(-27,+37) keV (chi2 = 40/58 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.4 (chi2 = 40/57 dof)
All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.
GCN Circular #20557
T. Sakamoto (AGU), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), N. Gehrels (GSFC), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+200 sec from the recent telemetry downlink, we report further analysis of BAT GRB 170126A (trigger #735188) (Kocevski, et al., GCN Circ. 20530). The BAT ground-calculated position is RA, Dec = 263.623, -64.755 deg which is
```
   RA(J2000)  =  17h 34m 29.4s
   Dec(J2000) = -64d 45' 18.9"
```
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 4%.
The mask-weighted light curve shows a single-peaked structure that starts at ~T-1 s, peaks at ~T+1 s, and ends at ~T+11 s. T90 (15-350 keV) is 9.5 +- 1.6 sec (estimated error including systematics).
The time-averaged spectrum from T-0.8 to T+10.9 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.54 +- 0.14. The fluence in the 15-150 keV band is 2.8 +- 0.3 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+0.31 sec in the 15-150 keV band is 7.3 +- 1.1 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/735188/BA/

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Jochen Greiner, last update: 28-Jan-2017 [Disclaimer]