Gamma-ray Burst 181126A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 26 Nov 18 09:54:22 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     873539,   Seg_Num: 0
GRB_RA:          152.351d {+10h 09m 24s} (J2000),
                 152.565d {+10h 10m 16s} (current),
                 151.784d {+10h 07m 08s} (1950)
GRB_DEC:         -29.679d {-29d 40' 43"} (J2000),
                 -29.772d {-29d 46' 19"} (current),
                 -29.433d {-29d 25' 58"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       793 [cnts]    Image_Peak=90 [image_cnts]
TRIGGER_DUR:     0.256 [sec] 
TRIGGER_INDEX:   123     E_range: 25-100 keV
BKG_INTEN:       12745 [cnts]
BKG_TIME:        35634.01 SOD {09:53:54.01} UT
BKG_DUR:         8 [sec]
GRB_DATE:        18448 TJD;   330 DOY;   18/11/26
GRB_TIME:        35648.09 SOD {09:54:08.09} UT
GRB_PHI:         -128.62 [deg]
GRB_THETA:        26.95 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     18.73 [sigma]
IMAGE_SIGNIF:    8.69 [sigma]
MERIT_PARAMS:     +1  +0  +0  -2  +2  -1  +0  +0 -18  +0 
SUN_POSTN:       242.10d {+16h 08m 23s}  -20.96d {-20d 57' 40"}
SUN_DIST:         79.38 [deg]   Sun_angle= 6.0 [hr] (West of Sun)
MOON_POSTN:      107.37d {+07h 09m 30s}  +21.30d {+21d 18' 07"}
MOON_DIST:        67.07 [deg]
MOON_ILLUM:      87 [%]
GAL_COORDS:      265.67, 21.23 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      167.33,-37.93 [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 = 312.85,18.15 [deg].

red DSS finding chart ps-file

GCN NOTICE

 
TITLE:           GCN/SWIFT NOTICE 
NOTICE_DATE:     Mon 26 Nov 18 09:55:29 UT 
NOTICE_TYPE:     Swift-XRT Nack-Position 
TRIGGER_NUM:     873539,   Seg_Num: 0 
POINT_RA:        152.335d {+10h 09m 20s} (J2000) 
POINT_DEC:       -29.672d {-29d 40' 18"} (J2000) 
IMG_START_DATE:  18448 TJD;   330 DOY;   18/11/26 
IMG_START_TIME:  35723.10 SOD {09:55:23.10} UT,   75.0 [sec] since BAT Trigger Time 
COUNTS:          4    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:     Mon 26 Nov 18 09:57:46 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     873539,   Seg_Num: 0
GRB_RA:          152.351d {+10h 09m 24s} (J2000),
                 152.565d {+10h 10m 16s} (current),
                 151.784d {+10h 07m 08s} (1950)
GRB_DEC:         -29.679d {-29d 40' 43"} (J2000),
                 -29.772d {-29d 46' 19"} (current),
                 -29.433d {-29d 25' 58"} (1950)
GRB_DATE:        18448 TJD;   330 DOY;   18/11/26
GRB_TIME:        35648.09 SOD {09:54:08.09} UT
TRIGGER_INDEX:   123
GRB_PHI:         -128.62 [deg]
GRB_THETA:        26.95 [deg]
DELTA_TIME:      32.00 [sec]
TRIGGER_DUR:     0.256 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     18.73 [sigma]
IMAGE_SIGNIF:    8.69 [sigma]
LC_URL:          sw00873539000msb.lc
SUN_POSTN:       242.10d {+16h 08m 24s}  -20.96d {-20d 57' 41"}
SUN_DIST:         79.38 [deg]   Sun_angle= 6.0 [hr] (West of Sun)
MOON_POSTN:      107.41d {+07h 09m 39s}  +21.30d {+21d 18' 03"}
MOON_DIST:        67.05 [deg]
MOON_ILLUM:      87 [%]
GAL_COORDS:      265.67, 21.23 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      167.33,-37.93 [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 = 312.85,18.15 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 26 Nov 18 09:58:28 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     873539,   Seg_Num: 0
POINT_RA:        152.335d {+10h 09m 20s} (J2000)
POINT_DEC:       -29.672d {-29d 40' 16"} (J2000)
POINT_ROLL:      108.302d
IMG_START_DATE:  18448 TJD;   330 DOY;   18/11/26
IMG_START_TIME:  35728.01 SOD {09:55:28.01} UT,   79.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.993
N_STARS:         71
X_OFFSET:        590 [pixels]
Y_OFFSET:        496 [pixels]
X_MAX:           1549 [pixels]
Y_MAX:           1455 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    8
SL_URL:          sw00873539000msufc0079.fits
SUN_POSTN:       242.10d {+16h 08m 24s}  -20.96d {-20d 57' 42"}
SUN_DIST:         79.40 [deg]   Sun_angle= 6.0 [hr] (West of Sun)
MOON_POSTN:      107.42d {+07h 09m 41s}  +21.30d {+21d 18' 02"}
MOON_DIST:        67.03 [deg]
MOON_ILLUM:      87 [%]
GAL_COORDS:      265.66, 21.23 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      167.31,-37.93 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 26 Nov 18 09:58:38 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     873539,   Seg_Num: 0
POINT_RA:        152.335d {+10h 09m 20s} (J2000)
POINT_DEC:       -29.672d {-29d 40' 16"} (J2000)
POINT_ROLL:      108.302d
IMG_START_DATE:  18448 TJD;   330 DOY;   18/11/26
IMG_START_TIME:  35728.01 SOD {09:55:28.01} UT,   79.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.993
N_STARS:         71
X_OFFSET:        590 [pixels]
Y_OFFSET:        496 [pixels]
X_MAX:           1549 [pixels]
Y_MAX:           1455 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    8
SL_URL:          sw00873539000msufc0079.fits
SUN_POSTN:       242.10d {+16h 08m 24s}  -20.96d {-20d 57' 42"}
SUN_DIST:         79.40 [deg]   Sun_angle= 6.0 [hr] (West of Sun)
MOON_POSTN:      107.42d {+07h 09m 41s}  +21.30d {+21d 18' 02"}
MOON_DIST:        67.03 [deg]
MOON_ILLUM:      87 [%]
GAL_COORDS:      265.66, 21.23 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      167.31,-37.93 [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:     Mon 26 Nov 18 09:59:53 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     873539,   Seg_Num: 0
POINT_RA:        152.335d {+10h 09m 20s} (J2000)
POINT_DEC:       -29.672d {-29d 40' 16"} (J2000)
ROLL:            108.302d
IMG_START_DATE:  18448 TJD;   330 DOY;   18/11/26
IMG_START_TIME:  35728.01 SOD {09:55:28.01} UT,   79.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     564918949
X_OFFSET:        909 [pixels]
Y_OFFSET:        815 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1069
Y_GRB_POS:       975
BINNING_INDEX:   1
IM_URL:          sw00873539000msuni0101.fits
SUN_POSTN:       242.10d {+16h 08m 24s}  -20.96d {-20d 57' 42"}
SUN_DIST:         79.40 [deg]   Sun_angle= 6.0 [hr] (West of Sun)
MOON_POSTN:      107.43d {+07h 09m 44s}  +21.30d {+21d 18' 01"}
MOON_DIST:        67.02 [deg]
MOON_ILLUM:      87 [%]
GAL_COORDS:      265.66, 21.23 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      167.31,-37.93 [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:     Mon 26 Nov 18 10:00:07 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     873539,   Seg_Num: 0
POINT_RA:        152.335d {+10h 09m 20s} (J2000)
POINT_DEC:       -29.672d {-29d 40' 16"} (J2000)
ROLL:            108.302d
IMG_START_DATE:  18448 TJD;   330 DOY;   18/11/26
IMG_START_TIME:  35728.01 SOD {09:55:28.01} UT,   79.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     564918949
X_OFFSET:        909 [pixels]
Y_OFFSET:        815 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1069
Y_GRB_POS:       975
BINNING_INDEX:   1
IM_URL:          sw00873539000msuni0101.fits
SUN_POSTN:       242.10d {+16h 08m 24s}  -20.96d {-20d 57' 42"}
SUN_DIST:         79.40 [deg]   Sun_angle= 6.0 [hr] (West of Sun)
MOON_POSTN:      107.44d {+07h 09m 45s}  +21.30d {+21d 18' 00"}
MOON_DIST:        67.02 [deg]
MOON_ILLUM:      87 [%]
GAL_COORDS:      265.66, 21.23 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      167.31,-37.93 [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:     Mon 26 Nov 18 09:59:33 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     873539,   Seg_Num: 0
GRB_RA:          152.3477d {+10h 09m 23.44s} (J2000),
                 152.5621d {+10h 10m 14.90s} (current),
                 151.7812d {+10h 07m 07.47s} (1950)
GRB_DEC:         -29.6861d {-29d 41' 09.9"} (J2000),
                 -29.7794d {-29d 46' 45.8"} (current),
                 -29.4401d {-29d 26' 24.4"} (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:  18448 TJD;   330 DOY;   18/11/26
IMG_START_TIME:  35747.00 SOD {09:55:47.00} UT,   98.9 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       242.10d {+16h 08m 24s}  -20.96d {-20d 57' 42"}
SUN_DIST:         79.39 [deg]   Sun_angle= 6.0 [hr] (West of Sun)
MOON_POSTN:      107.43d {+07h 09m 43s}  +21.30d {+21d 18' 01"}
MOON_DIST:        67.04 [deg]
MOON_ILLUM:      87 [%]
GAL_COORDS:      265.67, 21.22 [deg] galactic lon,lat of the burst
ECL_COORDS:      167.34,-37.93 [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 Circular #23453
E. Sonbas (Adiyaman Univ.), S. D. Barthelmy (GSFC), P. D'Avanzo (INAF-OAB), N. P. M. Kuin (UCL-MSSL), A. Melandri (INAF-OAB), K. L. Page (U Leicester) and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team:
At 09:54:08 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 181126A (trigger=873539). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 152.351, -29.679, which is
```
   RA(J2000)  =  10h 09m 24s
   Dec(J2000) = -29d 40' 43"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows two peaks with a total duration of about 2 sec. The peak count rate was ~5500 counts/sec (15-350 keV), at ~1 sec after the trigger.
The XRT began observing the field at 09:55:23.1 UT, 75.0 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 152.34775, -29.68611 which is equivalent to:
```
   RA(J2000)  = 10h 09m 23.46s
   Dec(J2000) = -29d 41' 10.0"
```
with an uncertainty of 3.9 arcseconds (radius, 90% containment). This location is 27 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 150 seconds with the White filter starting 79 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 19.6 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 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.07.
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:     Mon 26 Nov 18 10:07:13 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     873539,   Seg_Num: 0
POINT_RA:        152.331d {+10h 09m 20s} (J2000)
POINT_DEC:       -29.673d {-29d 40' 22"} (J2000)
POINT_ROLL:      108.305d
IMG_START_DATE:  18448 TJD;   330 DOY;   18/11/26
IMG_START_TIME:  35940.22 SOD {09:59:00.22} UT,   292.1 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.539
N_STARS:         190
X_OFFSET:        350 [pixels]
Y_OFFSET:        256 [pixels]
X_MAX:           1789 [pixels]
Y_MAX:           1695 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00873539000msufc0292.fits
SUN_POSTN:       242.11d {+16h 08m 26s}  -20.96d {-20d 57' 46"}
SUN_DIST:         79.41 [deg]   Sun_angle= 6.0 [hr] (West of Sun)
MOON_POSTN:      107.51d {+07h 10m 03s}  +21.30d {+21d 17' 52"}
MOON_DIST:        66.97 [deg]
MOON_ILLUM:      87 [%]
GAL_COORDS:      265.65, 21.22 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      167.31,-37.93 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 26 Nov 18 10:07:32 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     873539,   Seg_Num: 0
POINT_RA:        152.331d {+10h 09m 20s} (J2000)
POINT_DEC:       -29.673d {-29d 40' 22"} (J2000)
POINT_ROLL:      108.305d
IMG_START_DATE:  18448 TJD;   330 DOY;   18/11/26
IMG_START_TIME:  35940.22 SOD {09:59:00.22} UT,   292.1 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.539
N_STARS:         190
X_OFFSET:        350 [pixels]
Y_OFFSET:        256 [pixels]
X_MAX:           1789 [pixels]
Y_MAX:           1695 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00873539000msufc0292.fits
SUN_POSTN:       242.11d {+16h 08m 26s}  -20.96d {-20d 57' 46"}
SUN_DIST:         79.41 [deg]   Sun_angle= 6.0 [hr] (West of Sun)
MOON_POSTN:      107.52d {+07h 10m 04s}  +21.30d {+21d 17' 52"}
MOON_DIST:        66.97 [deg]
MOON_ILLUM:      87 [%]
GAL_COORDS:      265.65, 21.22 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      167.31,-37.93 [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:     Mon 26 Nov 18 10:08:35 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     873539,   Seg_Num: 0
POINT_RA:        152.331d {+10h 09m 20s} (J2000)
POINT_DEC:       -29.673d {-29d 40' 22"} (J2000)
ROLL:            108.305d
IMG_START_DATE:  18448 TJD;   330 DOY;   18/11/26
IMG_START_TIME:  35940.22 SOD {09:59:00.22} UT,   292.1 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     564919162
X_OFFSET:        909 [pixels]
Y_OFFSET:        815 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1069
Y_GRB_POS:       975
BINNING_INDEX:   1
IM_URL:          sw00873539000msuni0314.fits
SUN_POSTN:       242.11d {+16h 08m 26s}  -20.96d {-20d 57' 46"}
SUN_DIST:         79.41 [deg]   Sun_angle= 6.0 [hr] (West of Sun)
MOON_POSTN:      107.53d {+07h 10m 07s}  +21.30d {+21d 17' 50"}
MOON_DIST:        66.96 [deg]
MOON_ILLUM:      87 [%]
GAL_COORDS:      265.65, 21.22 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      167.31,-37.93 [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:     Mon 26 Nov 18 10:08:48 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     873539,   Seg_Num: 0
POINT_RA:        152.331d {+10h 09m 20s} (J2000)
POINT_DEC:       -29.673d {-29d 40' 22"} (J2000)
ROLL:            108.305d
IMG_START_DATE:  18448 TJD;   330 DOY;   18/11/26
IMG_START_TIME:  35940.22 SOD {09:59:00.22} UT,   292.1 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     564919162
X_OFFSET:        909 [pixels]
Y_OFFSET:        815 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1069
Y_GRB_POS:       975
BINNING_INDEX:   1
IM_URL:          sw00873539000msuni0314.fits
SUN_POSTN:       242.11d {+16h 08m 26s}  -20.96d {-20d 57' 47"}
SUN_DIST:         79.41 [deg]   Sun_angle= 6.0 [hr] (West of Sun)
MOON_POSTN:      107.53d {+07h 10m 07s}  +21.30d {+21d 17' 50"}
MOON_DIST:        66.96 [deg]
MOON_ILLUM:      87 [%]
GAL_COORDS:      265.65, 21.22 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      167.31,-37.93 [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:     Mon 26 Nov 18 10:08:05 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     873539,   Seg_Num: 0
GRB_RA:          152.3474d {+10h 09m 23.37s} (J2000),
                 152.5618d {+10h 10m 14.83s} (current),
                 151.7809d {+10h 07m 07.40s} (1950)
GRB_DEC:         -29.6875d {-29d 41' 15.0"} (J2000),
                 -29.7808d {-29d 46' 50.8"} (current),
                 -29.4415d {-29d 26' 29.5"} (1950)
GRB_ERROR:       2.6 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  18448 TJD;   330 DOY;   18/11/26
IMG_START_TIME:  35747.00 SOD {09:55:47.00} UT,   98.9 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       242.11d {+16h 08m 26s}  -20.96d {-20d 57' 46"}
SUN_DIST:         79.39 [deg]   Sun_angle= 6.0 [hr] (West of Sun)
MOON_POSTN:      107.52d {+07h 10m 05s}  +21.30d {+21d 17' 51"}
MOON_DIST:        66.98 [deg]
MOON_ILLUM:      87 [%]
GAL_COORDS:      265.67, 21.22 [deg] galactic lon,lat of the burst
ECL_COORDS:      167.34,-37.94 [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 Circular #23454
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Using promptly downlinked XRT event data for GRB 181126A, we find an enhanced XRT position of the afterglow: RA, Dec: 152.3477, -29.6875 which is equivalent to:
```
   RA (J2000)  = 10 09 23.46
   Dec (J2000) = -29 41 15.0
```
with an uncertainty of 2.5 arcseconds (radius, 90% confidence). Analysis of the promptly available data is online at http://www.swift.ac.uk/sper/873539.
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 NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 26 Nov 18 10:29:39 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     873539,   Seg_Num: 0
POINT_RA:        152.331d {+10h 09m 19s} (J2000)
POINT_DEC:       -29.673d {-29d 40' 21"} (J2000)
POINT_ROLL:      108.305d
IMG_START_DATE:  18448 TJD;   330 DOY;   18/11/26
IMG_START_TIME:  36516.91 SOD {10:08:36.91} UT,   868.8 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        7.991
N_STARS:         190
X_OFFSET:        350 [pixels]
Y_OFFSET:        256 [pixels]
X_MAX:           1789 [pixels]
Y_MAX:           1695 [pixels]
DET_THRESH:      25
PHOTO_THRESH:    15
SL_URL:          sw00873539000msufc0868.fits
SUN_POSTN:       242.12d {+16h 08m 29s}  -20.97d {-20d 57' 56"}
SUN_DIST:         79.42 [deg]   Sun_angle= 6.0 [hr] (West of Sun)
MOON_POSTN:      107.76d {+07h 11m 01s}  +21.29d {+21d 17' 24"}
MOON_DIST:        66.81 [deg]
MOON_ILLUM:      87 [%]
GAL_COORDS:      265.65, 21.22 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      167.31,-37.93 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 26 Nov 18 10:30:10 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     873539,   Seg_Num: 0
POINT_RA:        152.331d {+10h 09m 19s} (J2000)
POINT_DEC:       -29.673d {-29d 40' 21"} (J2000)
POINT_ROLL:      108.305d
IMG_START_DATE:  18448 TJD;   330 DOY;   18/11/26
IMG_START_TIME:  36516.91 SOD {10:08:36.91} UT,   868.8 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        7.991
N_STARS:         190
X_OFFSET:        350 [pixels]
Y_OFFSET:        256 [pixels]
X_MAX:           1789 [pixels]
Y_MAX:           1695 [pixels]
DET_THRESH:      25
PHOTO_THRESH:    15
SL_URL:          sw00873539000msufc0868.fits
SUN_POSTN:       242.12d {+16h 08m 30s}  -20.97d {-20d 57' 57"}
SUN_DIST:         79.42 [deg]   Sun_angle= 6.0 [hr] (West of Sun)
MOON_POSTN:      107.76d {+07h 11m 03s}  +21.29d {+21d 17' 24"}
MOON_DIST:        66.81 [deg]
MOON_ILLUM:      87 [%]
GAL_COORDS:      265.65, 21.22 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      167.31,-37.93 [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:     Mon 26 Nov 18 10:31:48 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     873539,   Seg_Num: 0
POINT_RA:        152.331d {+10h 09m 19s} (J2000)
POINT_DEC:       -29.673d {-29d 40' 21"} (J2000)
ROLL:            108.305d
IMG_START_DATE:  18448 TJD;   330 DOY;   18/11/26
IMG_START_TIME:  36516.91 SOD {10:08:36.91} UT,   868.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     564919738
X_OFFSET:        909 [pixels]
Y_OFFSET:        815 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1069
Y_GRB_POS:       975
BINNING_INDEX:   1
IM_URL:          sw00873539000msuni0890.fits
SUN_POSTN:       242.12d {+16h 08m 30s}  -20.97d {-20d 57' 57"}
SUN_DIST:         79.42 [deg]   Sun_angle= 6.0 [hr] (West of Sun)
MOON_POSTN:      107.78d {+07h 11m 07s}  +21.29d {+21d 17' 22"}
MOON_DIST:        66.80 [deg]
MOON_ILLUM:      87 [%]
GAL_COORDS:      265.65, 21.22 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      167.31,-37.93 [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:     Mon 26 Nov 18 10:32:02 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     873539,   Seg_Num: 0
POINT_RA:        152.331d {+10h 09m 19s} (J2000)
POINT_DEC:       -29.673d {-29d 40' 21"} (J2000)
ROLL:            108.305d
IMG_START_DATE:  18448 TJD;   330 DOY;   18/11/26
IMG_START_TIME:  36516.91 SOD {10:08:36.91} UT,   868.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     564919738
X_OFFSET:        909 [pixels]
Y_OFFSET:        815 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1069
Y_GRB_POS:       975
BINNING_INDEX:   1
IM_URL:          sw00873539000msuni0890.fits
SUN_POSTN:       242.12d {+16h 08m 30s}  -20.97d {-20d 57' 58"}
SUN_DIST:         79.42 [deg]   Sun_angle= 6.0 [hr] (West of Sun)
MOON_POSTN:      107.78d {+07h 11m 07s}  +21.29d {+21d 17' 21"}
MOON_DIST:        66.80 [deg]
MOON_ILLUM:      87 [%]
GAL_COORDS:      265.65, 21.22 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      167.31,-37.93 [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 #23455
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team.
Using 804 s of XRT Photon Counting mode data and 1 UVOT images for GRB 181126A, 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 = 152.34848, -29.68747 which is equivalent to:
```
RA (J2000): 10h 09m 23.64s
Dec (J2000): -29d 41' 14.9"
```
with an uncertainty of 2.3 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 #23457
E. Bissaldi (Politecnico & INFN Bari) reports on behalf of the Fermi GBM Team:
"At 09:54:09.94 UT on 26 November 2018, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 181126A (trigger 564918854/ 181126413), which was also detected by the Swift-BAT (Sonbas et al. 2018, GCN 23453). The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi-LAT boresight at the GBM trigger time is 111 degrees.
The GBM light curve consists of bright single pulse with a duration (T90) of about 0.6 s (50-300 keV). The time-averaged spectrum from T0-0.1 s to T0+0.4 s is adequately fit by a Band function with Epeak = 90 +/- 25 keV, alpha = -0.1 +/- 0.6, and beta = -2.1 +/- 0.2.
The event fluence (10-1000 keV) in this time interval is (4.8 +/- 0.5)E-07 erg/cm^2. The 64-ms peak photon flux measured starting from T0-64 ms in the 10-1000 keV band is 10.5 +/- 1.7 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN Circular #23458
N. R. Tanvir (U. Leicester) and W. Fong (Northwestern Univ.) report on behalf of a larger collaboration:
We observed the field of Swift GRB 181126A (Sonbas et al. GCN 23453) with the Gemini North telescope on Mauna Kea, beginning 2018-11-26 14:11 UT, approximately 4.3 hr post-burst. Images were obtained in the z filter using GMOS-N with total exposure of 15x60s.
No credible afterglow is visible at the revised X-ray position (Beardmore et al. GCN 23455) to a 3-sigma magnitude z(AB)=25.4, uncorrected for Galactic extinction.
We thank Mirko Simunovic and Christy Cunningham for efficiently executing these observations.
GCN Circular #23459
J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), A. Tohuvavohu (PSU), S. J. LaPorte (PSU), J.A. Kennea (PSU) and E. Sonbas report on behalf of the Swift-XRT team:
We have analysed 9.3 ks of XRT data for GRB 181126A (Sonbas et al. GCN Circ. 23453), from 82 s to 29.9 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN Circ. 23454).
The light curve can be modelled with a power-law decay with a decay index of alpha=0.95 (+/-0.09).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.7 (+0.8, -0.6). The best-fitting absorption column is 9.7 (+6.5, -4.2) x 10^21 cm^-2, in excess of the Galactic value of 8.1 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 (1.2 x 10^-10) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     9.7 (+6.5, -4.2) x 10^21 cm^-2
Galactic foreground: 8.1 x 10^20 cm^-2
Excess significance: 3.4 sigma
Photon index:	     2.7 (+0.8, -0.6)
```
If the light curve continues to decay with a power-law decay index of 0.95, the count rate at T+24 hours will be 9.5 x 10^-4 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.2 x 10^-14 (1.1 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/00873539.
This circular is an official product of the Swift-XRT team.
GCN Circular #23460
A. A. Breeveld (UCL-MSSL) and E. Sonbas (Adiyaman Univ.) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 181126A 80s after the BAT trigger (Sonbas et al., GCN Circ. 23453). No optical afterglow consistent with the XRT position (Beardmore et al., GCN Circ. 23455) 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

white_FC            80          230          147         >20.4
white               80         1181          342         >20.5
v                  622         1069           58         >18.0
b                 1147         1167           20         >18.2
u                  292         1142          285         >20.1
w1                 671         1118           58         >20.2
m2                 646         1093           58         >19.0
w2                 597         1044           58         >18.4
```
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 #23462
K. De (Caltech) reports on behalf of a larger collaboration
At 2018-11-26 14:13 UT, 4.32 hours after GRB 181126A (GCN 23453), we observed the location of the XRT counterpart (GCN 23455) with the MOSFIRE instrument on the Keck I telescope. With a total exposure time of 416 seconds, no afterglow is detected to a 3-sigma Ks-band limit of 23.6 AB mag.
GCN Circular #23463
M. Stamatikos (OSU), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), J. P. Norris (BSU), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), E. Sonbas (Adiyaman Univ.), 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 181126A (trigger #873539) (Sonbas et al., GCN Circ. 23453). The BAT ground-calculated position is RA, Dec = 152.350, -29.698 deg which is
```
  RA(J2000)  =  10h 09m 24.0s
  Dec(J2000) = -29d 41' 52.9"
```
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 68%.
The mask-weighted light curve shows two short pulses. The first pulse starts at ~ T-0.1 s, peaks at ~T0, and ends at ~T+0.2 s. The second pulse starts at ~T+1.6 s, peaks at ~T+1.8 s, and ends at ~T+2.2 s. T90 (15-350 keV) is 2.09 +- 0.12 sec (estimated error including systematics).
The time-averaged spectrum from T-0.07 to T+2.16 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index -0.13 +- 0.75, and Epeak of 83.8 +- 24.2 keV (chi squared 66.64 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 3.1 +- 0.4 x 10^-7 erg/cm2 and the 1-sec peak flux measured from T+1.22 sec in the 15-150 keV band is 2.7 +- 0.3 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.22 +- 0.15 (chi squared 79.71 for 57 d.o.f.). All the quoted errors are at the 90% confidence level.
Using the 8-ms binned light curve, the spectral lag for the 100-350 keV to 25-50 keV bands is 26 (+19, -15) ms for the first pulse, and 10 (+21, -13) ms for the second pulse. These lag values are intermediate between short and long GRBs, but also are consistent with short GRBs when considering the large error bars. In addition, no extended emission is found.
The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/873539/BA/
GCN Circular #23531
L. Rhodes, D. Williams (Oxford), R.P. Fender (Oxford/UCT), A.J. van der Horst (GWU), A. Horesh (HUJI), K. Mooley (NRAO/Caltech) and P.A. Woudt (UCT) report on behalf of the ThunderKAT collaboration:
“We observed the position of the GRB 181126A afterglow at 1.3 GHz with the new MeerKAT radio telescope on November 28, from 3.55 to 4.72 UT, i.e. 1.76 days after the burst (GCN 23453). We do not detect a radio source at the position of the X-ray counterpart (GCN 23455). The rms noise in the map around that position is 30 microJy per beam.
These observations were taken as part of the ThunderKAT Large Survey Project, a 5-year program for observations of transients with MeerKAT. We would like to thank the staff at the South African Radio Astronomy Observatory (SARAO) for scheduling and obtaining these observations.”

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Jochen Greiner, last update: 13-Dec-2018 [Disclaimer]