Gamma-ray Burst 170127A

(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:     Fri 27 Jan 17 14:22:20 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     735326,   Seg_Num: 0
GRB_RA:          174.336d {+11h 37m 21s} (J2000),
                 174.545d {+11h 38m 11s} (current),
                 173.725d {+11h 34m 54s} (1950)
GRB_DEC:         -45.852d {-45d 51' 05"} (J2000),
                 -45.946d {-45d 56' 46"} (current),
                 -45.575d {-45d 34' 29"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       39866 [cnts]    Image_Peak=614 [image_cnts]
TRIGGER_DUR:     12.160 [sec] 
TRIGGER_INDEX:   478     E_range: 25-100 keV
BKG_INTEN:       193739 [cnts]
BKG_TIME:        51581.47 SOD {14:19:41.47} UT
BKG_DUR:         64 [sec]
GRB_DATE:        17780 TJD;    27 DOY;   17/01/27
GRB_TIME:        51675.68 SOD {14:21:15.68} UT
GRB_PHI:         104.39 [deg]
GRB_THETA:         8.44 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     10.67 [sigma]
IMAGE_SIGNIF:    7.67 [sigma]
MERIT_PARAMS:     +1  +0  +0  +4  +2  -2  +0  +0 +25  +0 
SUN_POSTN:       310.26d {+20h 41m 02s}  -18.31d {-18d 18' 19"}
SUN_DIST:        104.29 [deg]   Sun_angle= 9.0 [hr] (West of Sun)
MOON_POSTN:      304.72d {+20h 18m 53s}  -16.81d {-16d 48' 49"}
MOON_DIST:       102.80 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      289.68, 15.11 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      197.79,-43.29 [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 = 184.43,16.15 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 27 Jan 17 14:23:25 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     735326,   Seg_Num: 0
GRB_RA:          174.3603d {+11h 37m 26.47s} (J2000),
                 174.5696d {+11h 38m 16.70s} (current),
                 173.7493d {+11h 35m 00.16s} (1950)
GRB_DEC:         -45.8371d {-45d 50' 13.5"} (J2000),
                 -45.9317d {-45d 55' 54.1"} (current),
                 -45.5602d {-45d 33' 36.6"} (1950)
GRB_ERROR:       5.9 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       7.10e-10 [erg/cm2/sec]
GRB_SIGNIF:      5.74 [sigma]
IMG_START_DATE:  17780 TJD;    27 DOY;   17/01/27
IMG_START_TIME:  51771.56 SOD {14:22:51.56} UT,   95.9 [sec] since BAT Trigger Time
TAM[0-3]:        327.69 237.20 261.73 243.56
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       310.26d {+20h 41m 02s}  -18.31d {-18d 18' 19"}
SUN_DIST:        104.29 [deg]   Sun_angle= 9.0 [hr] (West of Sun)
MOON_POSTN:      304.73d {+20h 18m 55s}  -16.81d {-16d 48' 43"}
MOON_DIST:       102.80 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      289.69, 15.12 [deg] galactic lon,lat of the burst
ECL_COORDS:      197.79,-43.27 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 1.34 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 27 Jan 17 14:23:42 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     735326,   Seg_Num: 0
GRB_RA:          174.3603d {+11h 37m 26.4s} (J2000),
                 174.5696d {+11h 38m 16.7s} (current),
                 173.7493d {+11h 35m 00.1s} (1950)
GRB_DEC:         -45.8371d {-45d 50' 13.5"} (J2000),
                 -45.9317d {-45d 55' 54.1"} (current),
                 -45.5602d {-45d 33' 36.6"} (1950)
GRB_ERROR:       5.8 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       33 [cnts]
IMG_START_DATE:  17780 TJD;    27 DOY;   17/01/27
IMG_START_TIME:  51771.56 SOD {14:22:51.56} UT,   95.9 [sec] since BAT Trigger Time
CENTROID_X:      329.55,  raw= 330  [pixels]
CENTROID_Y:      327.42,  raw= 327  [pixels]
ROLL:            136.99 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   68.41
GRB_POS_XRT_Z:   54.57
IMAGE_URL:       sw00735326000msxps_rw.img
SUN_POSTN:       310.26d {+20h 41m 02s}  -18.31d {-18d 18' 18"}
SUN_DIST:        104.29 [deg]   Sun_angle= 9.0 [hr] (West of Sun)
MOON_POSTN:      304.73d {+20h 18m 56s}  -16.81d {-16d 48' 42"}
MOON_DIST:       102.80 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      289.69, 15.12 [deg] galactic lon,lat of the burst
ECL_COORDS:      197.79,-43.27 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 27 Jan 17 14:23:35 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     735326,   Seg_Num: 0
GRB_RA:          174.3603d {+11h 37m 26.4s} (J2000),
                 174.5696d {+11h 38m 16.7s} (current),
                 173.7493d {+11h 35m 00.1s} (1950)
GRB_DEC:         -45.8371d {-45d 50' 13.5"} (J2000),
                 -45.9317d {-45d 55' 54.1"} (current),
                 -45.5602d {-45d 33' 36.6"} (1950)
GRB_ERROR:       5.8 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       33 [cnts]
IMG_START_DATE:  17780 TJD;    27 DOY;   17/01/27
IMG_START_TIME:  51771.56 SOD {14:22:51.56} UT,   95.9 [sec] since BAT Trigger Time
CENTROID_X:      329.55,  raw= 330  [pixels]
CENTROID_Y:      327.42,  raw= 327  [pixels]
ROLL:            136.99 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   68.41
GRB_POS_XRT_Z:   54.57
IMAGE_URL:       sw00735326000msxps_rw.img
SUN_POSTN:       310.26d {+20h 41m 02s}  -18.31d {-18d 18' 18"}
SUN_DIST:        104.29 [deg]   Sun_angle= 9.0 [hr] (West of Sun)
MOON_POSTN:      304.73d {+20h 18m 56s}  -16.81d {-16d 48' 43"}
MOON_DIST:       102.80 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      289.69, 15.12 [deg] galactic lon,lat of the burst
ECL_COORDS:      197.79,-43.27 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 27 Jan 17 14:25:02 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     735326,   Seg_Num: 0
GRB_RA:          174.336d {+11h 37m 21s} (J2000),
                 174.545d {+11h 38m 11s} (current),
                 173.725d {+11h 34m 54s} (1950)
GRB_DEC:         -45.852d {-45d 51' 05"} (J2000),
                 -45.946d {-45d 56' 46"} (current),
                 -45.575d {-45d 34' 29"} (1950)
GRB_DATE:        17780 TJD;    27 DOY;   17/01/27
GRB_TIME:        51675.68 SOD {14:21:15.68} UT
TRIGGER_INDEX:   478
GRB_PHI:         104.39 [deg]
GRB_THETA:         8.44 [deg]
DELTA_TIME:      19.00 [sec]
TRIGGER_DUR:     12.160 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     10.67 [sigma]
IMAGE_SIGNIF:    7.67 [sigma]
LC_URL:          sw00735326000msb.lc
SUN_POSTN:       310.26d {+20h 41m 02s}  -18.31d {-18d 18' 18"}
SUN_DIST:        104.29 [deg]   Sun_angle= 9.0 [hr] (West of Sun)
MOON_POSTN:      304.75d {+20h 18m 59s}  -16.81d {-16d 48' 36"}
MOON_DIST:       102.81 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      289.68, 15.11 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      197.79,-43.29 [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 = 184.43,16.15 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 27 Jan 17 14:27:37 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     735326,   Seg_Num: 0
POINT_RA:        174.355d {+11h 37m 25s} (J2000)
POINT_DEC:       -45.860d {-45d 51' 36"} (J2000)
POINT_ROLL:      136.993d
IMG_START_DATE:  17780 TJD;    27 DOY;   17/01/27
IMG_START_TIME:  51777.30 SOD {14:22:57.30} UT,   101.6 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.614
N_STARS:         190
X_OFFSET:        128 [pixels]
Y_OFFSET:        392 [pixels]
X_MAX:           1567 [pixels]
Y_MAX:           1831 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw00735326000msufc0101.fits
SUN_POSTN:       310.26d {+20h 41m 03s}  -18.30d {-18d 18' 16"}
SUN_DIST:        104.28 [deg]   Sun_angle= 9.0 [hr] (West of Sun)
MOON_POSTN:      304.77d {+20h 19m 05s}  -16.81d {-16d 48' 23"}
MOON_DIST:       102.81 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      289.70, 15.10 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      197.81,-43.29 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 27 Jan 17 14:28:09 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     735326,   Seg_Num: 0
POINT_RA:        174.355d {+11h 37m 25s} (J2000)
POINT_DEC:       -45.860d {-45d 51' 36"} (J2000)
POINT_ROLL:      136.993d
IMG_START_DATE:  17780 TJD;    27 DOY;   17/01/27
IMG_START_TIME:  51777.30 SOD {14:22:57.30} UT,   101.6 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.614
N_STARS:         190
X_OFFSET:        128 [pixels]
Y_OFFSET:        392 [pixels]
X_MAX:           1567 [pixels]
Y_MAX:           1831 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw00735326000msufc0101.fits
SUN_POSTN:       310.26d {+20h 41m 03s}  -18.30d {-18d 18' 15"}
SUN_DIST:        104.28 [deg]   Sun_angle= 9.0 [hr] (West of Sun)
MOON_POSTN:      304.77d {+20h 19m 06s}  -16.81d {-16d 48' 21"}
MOON_DIST:       102.82 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      289.70, 15.10 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      197.81,-43.29 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 27 Jan 17 14:28:56 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     735326,   Seg_Num: 0
POINT_RA:        174.355d {+11h 37m 25s} (J2000)
POINT_DEC:       -45.860d {-45d 51' 36"} (J2000)
ROLL:            136.993d
IMG_START_DATE:  17780 TJD;    27 DOY;   17/01/27
IMG_START_TIME:  51777.30 SOD {14:22:57.30} UT,   101.6 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     507219795
X_OFFSET:        619 [pixels]
Y_OFFSET:        808 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       779
Y_GRB_POS:       968
BINNING_INDEX:   1
IM_URL:          sw00735326000msuni0120.fits
SUN_POSTN:       310.26d {+20h 41m 03s}  -18.30d {-18d 18' 15"}
SUN_DIST:        104.28 [deg]   Sun_angle= 9.0 [hr] (West of Sun)
MOON_POSTN:      304.78d {+20h 19m 08s}  -16.80d {-16d 48' 17"}
MOON_DIST:       102.82 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      289.70, 15.10 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      197.81,-43.29 [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:     Fri 27 Jan 17 14:29:18 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     735326,   Seg_Num: 0
POINT_RA:        174.355d {+11h 37m 25s} (J2000)
POINT_DEC:       -45.860d {-45d 51' 36"} (J2000)
ROLL:            136.993d
IMG_START_DATE:  17780 TJD;    27 DOY;   17/01/27
IMG_START_TIME:  51777.30 SOD {14:22:57.30} UT,   101.6 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     507219795
X_OFFSET:        619 [pixels]
Y_OFFSET:        808 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       779
Y_GRB_POS:       968
BINNING_INDEX:   1
IM_URL:          sw00735326000msuni0120.fits
SUN_POSTN:       310.26d {+20h 41m 03s}  -18.30d {-18d 18' 15"}
SUN_DIST:        104.28 [deg]   Sun_angle= 9.0 [hr] (West of Sun)
MOON_POSTN:      304.79d {+20h 19m 08s}  -16.80d {-16d 48' 15"}
MOON_DIST:       102.82 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      289.70, 15.10 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      197.81,-43.29 [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 Circular #20538
C. B. Markwardt (NASA/GSFC), S. D. Barthelmy (GSFC), S. B. Cenko (GSFC), A. Cholden-Brown (PSU), A. D'Ai (INAF-IASFPA), V. D'Elia (ASDC), J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the Swift Team:
At 14:21:15 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 170127A (trigger=735326). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 174.336, -45.852, which is
```
   RA(J2000)  =  11h 37m 21s
   Dec(J2000) = -45d 51' 05"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a couple weak peaks with a duration of about 35 sec. The peak count rate was ~900 counts/sec (15-350 keV), at ~5 sec after the trigger.
The XRT began observing the field at 14:22:51.5 UT, 95.9 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 174.35974, -45.83603 which is equivalent to:
```
   RA(J2000)  = 11h 37m 26.34s
   Dec(J2000) = -45d 50' 09.7"
```
with an uncertainty of 4.1 arcseconds (radius, 90% containment). This location is 82 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.
The initial flux in the 2.5 s image was 7.10e-10 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 250 seconds with the U filter starting 101 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.2 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18.0 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.07.
Burst Advocate for this burst is C. B. Markwardt (Craig.Markwardt AT nasa.gov). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.)

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 27 Jan 17 14:40:42 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     735326,   Seg_Num: 0
POINT_RA:        174.356d {+11h 37m 25s} (J2000)
POINT_DEC:       -45.863d {-45d 51' 46"} (J2000)
POINT_ROLL:      136.993d
IMG_START_DATE:  17780 TJD;    27 DOY;   17/01/27
IMG_START_TIME:  52535.16 SOD {14:35:35.16} UT,   859.5 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.446
N_STARS:         190
X_OFFSET:        59 [pixels]
Y_OFFSET:        248 [pixels]
X_MAX:           1498 [pixels]
Y_MAX:           1687 [pixels]
DET_THRESH:      6
PHOTO_THRESH:    3
SL_URL:          sw00735326000msufc0859.fits
SUN_POSTN:       310.27d {+20h 41m 05s}  -18.30d {-18d 18' 07"}
SUN_DIST:        104.28 [deg]   Sun_angle= 9.0 [hr] (West of Sun)
MOON_POSTN:      304.89d {+20h 19m 34s}  -16.79d {-16d 47' 20"}
MOON_DIST:       102.89 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      289.70, 15.10 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      197.81,-43.29 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 27 Jan 17 14:41:03 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     735326,   Seg_Num: 0
POINT_RA:        174.356d {+11h 37m 25s} (J2000)
POINT_DEC:       -45.863d {-45d 51' 46"} (J2000)
POINT_ROLL:      136.993d
IMG_START_DATE:  17780 TJD;    27 DOY;   17/01/27
IMG_START_TIME:  52535.16 SOD {14:35:35.16} UT,   859.5 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.446
N_STARS:         190
X_OFFSET:        59 [pixels]
Y_OFFSET:        248 [pixels]
X_MAX:           1498 [pixels]
Y_MAX:           1687 [pixels]
DET_THRESH:      6
PHOTO_THRESH:    3
SL_URL:          sw00735326000msufc0859.fits
SUN_POSTN:       310.27d {+20h 41m 05s}  -18.30d {-18d 18' 07"}
SUN_DIST:        104.28 [deg]   Sun_angle= 9.0 [hr] (West of Sun)
MOON_POSTN:      304.89d {+20h 19m 34s}  -16.79d {-16d 47' 18"}
MOON_DIST:       102.89 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      289.70, 15.10 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      197.81,-43.29 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 27 Jan 17 14:41:21 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     735326,   Seg_Num: 0
GRB_RA:          174.3600d {+11h 37m 26.40s} (J2000),
                 174.5693d {+11h 38m 16.63s} (current),
                 173.7490d {+11h 35m 00.23s} (1950)
GRB_DEC:         -45.8357d {-45d 50' 08.5"} (J2000),
                 -45.9303d {-45d 55' 49.1"} (current),
                 -45.5588d {-45d 33' 31.6"} (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:  17780 TJD;    27 DOY;   17/01/27
IMG_START_TIME:  51948.00 SOD {14:25:48.00} UT,   272.3 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       310.27d {+20h 41m 05s}  -18.30d {-18d 18' 07"}
SUN_DIST:        104.30 [deg]   Sun_angle= 9.0 [hr] (West of Sun)
MOON_POSTN:      304.90d {+20h 19m 35s}  -16.79d {-16d 47' 17"}
MOON_DIST:       102.91 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      289.69, 15.13 [deg] galactic lon,lat of the burst
ECL_COORDS:      197.79,-43.27 [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 0.11% < P(seren) < 0.58%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 27 Jan 17 14:42:00 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     735326,   Seg_Num: 0
POINT_RA:        174.356d {+11h 37m 25s} (J2000)
POINT_DEC:       -45.863d {-45d 51' 46"} (J2000)
ROLL:            136.993d
IMG_START_DATE:  17780 TJD;    27 DOY;   17/01/27
IMG_START_TIME:  52535.16 SOD {14:35:35.16} UT,   859.5 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     507220553
X_OFFSET:        618 [pixels]
Y_OFFSET:        807 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       778
Y_GRB_POS:       967
BINNING_INDEX:   1
IM_URL:          sw00735326000msuni0878.fits
SUN_POSTN:       310.27d {+20h 41m 05s}  -18.30d {-18d 18' 06"}
SUN_DIST:        104.28 [deg]   Sun_angle= 9.0 [hr] (West of Sun)
MOON_POSTN:      304.90d {+20h 19m 36s}  -16.79d {-16d 47' 14"}
MOON_DIST:       102.90 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      289.70, 15.10 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      197.81,-43.29 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 27 Jan 17 14:42:34 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     735326,   Seg_Num: 0
POINT_RA:        174.356d {+11h 37m 25s} (J2000)
POINT_DEC:       -45.863d {-45d 51' 46"} (J2000)
ROLL:            136.993d
IMG_START_DATE:  17780 TJD;    27 DOY;   17/01/27
IMG_START_TIME:  52535.16 SOD {14:35:35.16} UT,   859.5 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     507220553
X_OFFSET:        618 [pixels]
Y_OFFSET:        807 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       778
Y_GRB_POS:       967
BINNING_INDEX:   1
IM_URL:          sw00735326000msuni0878.fits
SUN_POSTN:       310.27d {+20h 41m 05s}  -18.30d {-18d 18' 06"}
SUN_DIST:        104.28 [deg]   Sun_angle= 9.0 [hr] (West of Sun)
MOON_POSTN:      304.91d {+20h 19m 38s}  -16.79d {-16d 47' 11"}
MOON_DIST:       102.90 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      289.70, 15.10 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      197.81,-43.29 [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 #20539
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Using promptly downlinked XRT event data for GRB 170127A, we find an enhanced XRT position of the afterglow: RA, Dec: 174.3600, -45.8358 which is equivalent to:
```
   RA (J2000)  = 11 37 26.41
   Dec (J2000) = -45 50 08.7
```
with an uncertainty of 2.2 arcseconds (radius, 90% confidence). Analysis of the promptly available data is online at http://www.swift.ac.uk/sper/735326.
Position enhancement is is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177).
This circular is an official product of the Swift-XRT team.
GCN Circular #20548
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team.
Using 1366 s of XRT Photon Counting mode data and 2 UVOT images for GRB 170127A, 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 = 174.35970, -45.83565 which is equivalent to:
```
RA (J2000): 11h 37m 26.33s
Dec (J2000): -45d 50' 08.3"
```
with an uncertainty of 2.4 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 #20552
F. E. Marshall (NASA/GSFC) and C. B. Markwardt (NASA/GSFC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 170127A 102 s after the BAT trigger (Markwardt et al., GCN Circ. 20538). No optical afterglow consistent with the enhanced XRT position (Evans et al. GCN Circ. 20548) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

u_FC               102          351          246         >20.5
v                  409         1533          136         >18.7
b                  359         1632          175         >20.4
u                  102         1607          529         >20.7
w1                 458         1583          136         >19.4
m2                 434         1558          136         >20.0
w2                 385         1658          175         >20.2
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.07 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #20558
J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), S. J. LaPorte (PSU), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), B. Mingo (U. Leicester) and report on behalf of the Swift-XRT team: report on behalf of the Swift-XRT team:
We have analysed 6.2 ks of XRT data for GRB 170127A, from 86 s to 58.8 ks after the BAT trigger. The data comprise 168 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 an initial power-law decay with an index of alpha=1.28 (+/-0.15), followed by a break at T+329 s to an alpha of 8.0 (+0.0, -1.1).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.49 (+/-0.10). The best-fitting absorption column is 1.3 (+/-0.4) x 10^21 cm^-2, in excess of the Galactic value of 8.5 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 (5.0 x 10^-11) erg cm^-2 count^-1.
A summary of the WT-mode spectrum is thus:
```
Total column:	     1.3 (+/-0.4) x 10^21 cm^-2
Galactic foreground: 8.5 x 10^20 cm^-2
Excess significance: 2.0 sigma
Photon index:	     1.49 (+/-0.10)
```
If the light curve continues to decay with a power-law decay index of 5.19, the count rate at T+24 hours will be 2.0 x 10^-13 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.9 x 10^-24 (10.0 x 10^-24) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00735326.
This circular is an official product of the Swift-XRT team.
GCN Circular #20562
P. Schady, P. Wiseman and J. Greiner (all at MPE Garching) report on behalf of the GROND team:
We observed the field of GRB 170127A (Swift trigger 735326; Markwardt et al., GCN #20538) 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 05:23 UT on 2017-01-27, 15 hrs after the GRB trigger. They were performed at high seeing that varied between 1.5" and 2" and at an average airmass of 1.4.
In combined images with 36 min of total exposures in g'r'i'z' and 30 min in JHK at a mid-time of 05:40 UT on 2017-01-28, we do not detect a source within the Swift-XRT error circle reported by Evans et al. (GCN #20548) down to the following 3 sigma upper limits (all in AB system)
```
g' > 24.0 mag
r' > 23.7 mag
i' > 23.1 mag
z' > 23.0 mag
J > 20.7 mag
H > 20.3 mag
K > 17.7 mag
```
Given magnitudes are calibrated against GROND zeropoints and 2MASS field stars and are not corrected for the Galactic foreground extinction corresponding to a reddening of E_(B-V)=3D 0.06 in the direction of the burst (Schlafly & Finkbeiner 2011).
GCN Circular #20565
M. Stamatikos (OSU), 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), T. Sakamoto (AGU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 170127A (trigger #735326) (Markwardt et al., GCN Circ. 20538). The BAT ground-calculated position is RA, Dec = 174.382, -45.827 deg which is
```
   RA(J2000)  =  11h 37m 31.6s
   Dec(J2000) = -45d 49' 38.6"
```
with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 97%.
The mask-weighted light curve shows some weak overlapping pulses that starts at ~T-5 s and ends at ~T+65 s. T90 (15-350 keV) is 62.26 +- 10.39 sec (estimated error including systematics).
The time-averaged spectrum from T-4.65 to T+64.51 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.10 +- 0.30. The fluence in the 15-150 keV band is 5.2 +- 1.0 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+7.31 sec in the 15-150 keV band is 0.3 +- 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/735326/BA/

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Jochen Greiner, last update: 29-Jan-2017 [Disclaimer]