Gamma-ray Burst 181123B

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 23 Nov 18 05:33:23 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     873186,   Seg_Num: 0
GRB_RA:          184.348d {+12h 17m 23s} (J2000),
                 184.588d {+12h 18m 21s} (current),
                 183.713d {+12h 14m 51s} (1950)
GRB_DEC:         +14.589d {+14d 35' 22"} (J2000),
                 +14.485d {+14d 29' 05"} (current),
                 +14.867d {+14d 52' 02"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       1013 [cnts]    Image_Peak=101 [image_cnts]
TRIGGER_DUR:     0.256 [sec] 
TRIGGER_INDEX:   481     E_range: 50-350 keV
BKG_INTEN:       11434 [cnts]
BKG_TIME:        19970.03 SOD {05:32:50.03} UT
BKG_DUR:         8 [sec]
GRB_DATE:        18445 TJD;   327 DOY;   18/11/23
GRB_TIME:        19983.09 SOD {05:33:03.09} UT
GRB_PHI:          39.75 [deg]
GRB_THETA:        27.62 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     33.10 [sigma]
IMAGE_SIGNIF:    8.80 [sigma]
MERIT_PARAMS:     +1  +0  +0  -2  +3  -1  +0  +0 -44  +0 
SUN_POSTN:       238.73d {+15h 54m 54s}  -20.33d {-20d 19' 46"}
SUN_DIST:         63.58 [deg]   Sun_angle= 3.6 [hr] (West of Sun)
MOON_POSTN:       59.44d {+03h 57m 46s}  +16.05d {+16d 03' 16"}
MOON_DIST:       117.80 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      268.92, 75.16 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      178.05, 15.09 [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 = 55.72,15.70 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Fri 23 Nov 18 05:33:42 UT
NOTICE_TYPE:    INTEGRAL SPI ACS Trigger
TRIGGER_NUM:    8166,   Sub_Num: 0
GRB_INTEN:      10.00 [sigma]  
GRB_TIME:       19983.12 SOD {05:33:03.12} UT
GRB_DATE:       18445 TJD;   327 DOY;   18/11/23
COMMENTS:       INTEGRAL SPI_ACS GRB Trigger.
COMMENTS:       Time_Scale=0.2000 and Time_Error=0.1000.
COMMENTS:
COMMENTS:       NOTE: This SPIACS event is temporally(0.0<100sec) coincident with the SWIFT_BAT event (trignum=873186).
COMMENTS:
COMMENTS:       The SPIACS lightcurve can be found at:
COMMENTS:       ftp://isdcarc.unige.ch/arc/FTP/ibas/spiacs/2018-11/2018-11-23T05-33-03.0613-01999-11152-0.lc

GCN NOTICE

 
TITLE:           GCN/SWIFT NOTICE 
NOTICE_DATE:     Fri 23 Nov 18 05:34:33 UT 
NOTICE_TYPE:     Swift-XRT Nack-Position 
TRIGGER_NUM:     873186,   Seg_Num: 0 
POINT_RA:        184.364d {+12h 17m 27s} (J2000) 
POINT_DEC:       +14.588d {+14d 35' 15"} (J2000) 
IMG_START_DATE:  18445 TJD;   327 DOY;   18/11/23 
IMG_START_TIME:  20063.35 SOD {05:34:23.35} UT,   80.3 [sec] since BAT Trigger Time 
COUNTS:          1    Min_needed= 20 
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec] 
PH2_ITER:        0    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:     Fri 23 Nov 18 05:37:32 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     873186,   Seg_Num: 0
POINT_RA:        184.364d {+12h 17m 27s} (J2000)
POINT_DEC:       +14.588d {+14d 35' 15"} (J2000)
POINT_ROLL:      121.876d
IMG_START_DATE:  18445 TJD;   327 DOY;   18/11/23
IMG_START_TIME:  20066.57 SOD {05:34:26.57} UT,   83.5 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.316
N_STARS:         20
X_OFFSET:        406 [pixels]
Y_OFFSET:        665 [pixels]
X_MAX:           1365 [pixels]
Y_MAX:           1624 [pixels]
DET_THRESH:      17
PHOTO_THRESH:    10
SL_URL:          sw00873186000msufc0083.fits
SUN_POSTN:       238.73d {+15h 54m 55s}  -20.33d {-20d 19' 48"}
SUN_DIST:         63.57 [deg]   Sun_angle= 3.6 [hr] (West of Sun)
MOON_POSTN:       59.48d {+03h 57m 56s}  +16.06d {+16d 03' 52"}
MOON_DIST:       117.78 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      268.97, 75.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      178.06, 15.09 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 23 Nov 18 05:37:49 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     873186,   Seg_Num: 0
POINT_RA:        184.364d {+12h 17m 27s} (J2000)
POINT_DEC:       +14.588d {+14d 35' 15"} (J2000)
POINT_ROLL:      121.876d
IMG_START_DATE:  18445 TJD;   327 DOY;   18/11/23
IMG_START_TIME:  20066.57 SOD {05:34:26.57} UT,   83.5 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.316
N_STARS:         20
X_OFFSET:        406 [pixels]
Y_OFFSET:        665 [pixels]
X_MAX:           1365 [pixels]
Y_MAX:           1624 [pixels]
DET_THRESH:      17
PHOTO_THRESH:    10
SL_URL:          sw00873186000msufc0083.fits
SUN_POSTN:       238.73d {+15h 54m 55s}  -20.33d {-20d 19' 48"}
SUN_DIST:         63.57 [deg]   Sun_angle= 3.6 [hr] (West of Sun)
MOON_POSTN:       59.49d {+03h 57m 57s}  +16.07d {+16d 03' 54"}
MOON_DIST:       117.78 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      268.97, 75.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      178.06, 15.09 [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 23 Nov 18 05:38:03 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     873186,   Seg_Num: 0
GRB_RA:          184.348d {+12h 17m 23s} (J2000),
                 184.588d {+12h 18m 21s} (current),
                 183.713d {+12h 14m 51s} (1950)
GRB_DEC:         +14.589d {+14d 35' 22"} (J2000),
                 +14.485d {+14d 29' 05"} (current),
                 +14.867d {+14d 52' 02"} (1950)
GRB_DATE:        18445 TJD;   327 DOY;   18/11/23
GRB_TIME:        19983.09 SOD {05:33:03.09} UT
TRIGGER_INDEX:   481
GRB_PHI:          39.75 [deg]
GRB_THETA:        27.62 [deg]
DELTA_TIME:      -25.00 [sec]
TRIGGER_DUR:     0.256 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     33.10 [sigma]
IMAGE_SIGNIF:    8.80 [sigma]
LC_URL:          sw00873186000msb.lc
SUN_POSTN:       238.73d {+15h 54m 55s}  -20.33d {-20d 19' 48"}
SUN_DIST:         63.58 [deg]   Sun_angle= 3.6 [hr] (West of Sun)
MOON_POSTN:       59.49d {+03h 57m 57s}  +16.07d {+16d 03' 56"}
MOON_DIST:       117.76 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      268.92, 75.16 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      178.05, 15.09 [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 = 55.72,15.70 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 23 Nov 18 05:38:30 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     873186,   Seg_Num: 0
GRB_RA:          184.3666d {+12h 17m 27.98s} (J2000),
                 184.6065d {+12h 18m 25.57s} (current),
                 183.7313d {+12h 14m 55.50s} (1950)
GRB_DEC:         +14.5988d {+14d 35' 55.6"} (J2000),
                 +14.4939d {+14d 29' 38.1"} (current),
                 +14.8765d {+14d 52' 35.4"} (1950)
GRB_ERROR:       3.8 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  18445 TJD;   327 DOY;   18/11/23
IMG_START_TIME:  20100.00 SOD {05:35:00.00} UT,   116.9 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       238.73d {+15h 54m 55s}  -20.33d {-20d 19' 48"}
SUN_DIST:         63.57 [deg]   Sun_angle= 3.6 [hr] (West of Sun)
MOON_POSTN:       59.49d {+03h 57m 58s}  +16.07d {+16d 03' 60"}
MOON_DIST:       117.77 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      268.96, 75.18 [deg] galactic lon,lat of the burst
ECL_COORDS:      178.06, 15.10 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.58% < P(seren) < 1.1%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 23 Nov 18 05:39:43 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     873186,   Seg_Num: 0
POINT_RA:        184.364d {+12h 17m 27s} (J2000)
POINT_DEC:       +14.588d {+14d 35' 15"} (J2000)
ROLL:            121.876d
IMG_START_DATE:  18445 TJD;   327 DOY;   18/11/23
IMG_START_TIME:  20066.57 SOD {05:34:26.57} UT,   83.5 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     564644088
X_OFFSET:        725 [pixels]
Y_OFFSET:        984 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       885
Y_GRB_POS:       1144
BINNING_INDEX:   1
IM_URL:          sw00873186000msuni0105.fits
SUN_POSTN:       238.73d {+15h 54m 55s}  -20.33d {-20d 19' 49"}
SUN_DIST:         63.57 [deg]   Sun_angle= 3.6 [hr] (West of Sun)
MOON_POSTN:       59.50d {+03h 58m 01s}  +16.07d {+16d 04' 10"}
MOON_DIST:       117.76 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      268.97, 75.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      178.06, 15.09 [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).  
COMMENTS:        This notice was forced out after watchdog timer expiring -- most likely due to missing packet(s);  
COMMENTS:        as a consequence some of the fields may be incoorect (eg TRIGGER_NUM,RA,DEC).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 23 Nov 18 05:39:59 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     873186,   Seg_Num: 0
POINT_RA:        184.364d {+12h 17m 27s} (J2000)
POINT_DEC:       +14.588d {+14d 35' 15"} (J2000)
ROLL:            121.876d
IMG_START_DATE:  18445 TJD;   327 DOY;   18/11/23
IMG_START_TIME:  20066.57 SOD {05:34:26.57} UT,   83.5 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     564644088
X_OFFSET:        725 [pixels]
Y_OFFSET:        984 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       885
Y_GRB_POS:       1144
BINNING_INDEX:   1
IM_URL:          sw00873186000msuni0105.fits
SUN_POSTN:       238.73d {+15h 54m 55s}  -20.33d {-20d 19' 49"}
SUN_DIST:         63.57 [deg]   Sun_angle= 3.6 [hr] (West of Sun)
MOON_POSTN:       59.51d {+03h 58m 02s}  +16.07d {+16d 04' 13"}
MOON_DIST:       117.76 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      268.97, 75.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      178.06, 15.09 [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.  
COMMENTS:        This notice was forced out after watchdog timer expiring -- most likely due to missing packet(s);  
COMMENTS:        as a consequence some of the fields may be incoorect (eg TRIGGER_NUM,RA,DEC).

GCN Circular #23432
A. Y. Lien (GSFC/UMBC), P. D'Avanzo (INAF-OAB) and D. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift Observatory Team:
At 05:33:03 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 181123B (trigger=873186). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 184.348, +14.589 which is
```
   RA(J2000) = 12h 17m 23s
   Dec(J2000) = +14d 35' 22"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single peak structure with a duration of about 0.4 sec. The peak count rate was ~5000 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 05:34:23.3 UT, 80.2 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 184.36663, 14.59889 which is equivalent to:
```
   RA(J2000)  = 12h 17m 27.99s
   Dec(J2000) = +14d 35' 56.0"
```
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This location is 74 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 83 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 0.03.
Burst Advocate for this burst is A. Y. Lien (amy.y.lien 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 23 Nov 18 06:02:05 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     873186,   Seg_Num: 0
POINT_RA:        184.367d {+12h 17m 28s} (J2000)
POINT_DEC:       +14.588d {+14d 35' 19"} (J2000)
POINT_ROLL:      121.877d
IMG_START_DATE:  18445 TJD;   327 DOY;   18/11/23
IMG_START_TIME:  20279.23 SOD {05:37:59.23} UT,   296.1 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.597
N_STARS:         14
X_OFFSET:        166 [pixels]
Y_OFFSET:        425 [pixels]
X_MAX:           1605 [pixels]
Y_MAX:           1864 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw00873186000msufc0296.fits
SUN_POSTN:       238.75d {+15h 54m 59s}  -20.33d {-20d 20' 01"}
SUN_DIST:         63.58 [deg]   Sun_angle= 3.6 [hr] (West of Sun)
MOON_POSTN:       59.72d {+03h 58m 54s}  +16.12d {+16d 07' 23"}
MOON_DIST:       117.55 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      268.98, 75.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      178.07, 15.09 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 23 Nov 18 06:02:21 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     873186,   Seg_Num: 0
POINT_RA:        184.367d {+12h 17m 28s} (J2000)
POINT_DEC:       +14.588d {+14d 35' 19"} (J2000)
POINT_ROLL:      121.877d
IMG_START_DATE:  18445 TJD;   327 DOY;   18/11/23
IMG_START_TIME:  20279.23 SOD {05:37:59.23} UT,   296.1 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.597
N_STARS:         14
X_OFFSET:        166 [pixels]
Y_OFFSET:        425 [pixels]
X_MAX:           1605 [pixels]
Y_MAX:           1864 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw00873186000msufc0296.fits
SUN_POSTN:       238.75d {+15h 54m 59s}  -20.33d {-20d 20' 01"}
SUN_DIST:         63.58 [deg]   Sun_angle= 3.6 [hr] (West of Sun)
MOON_POSTN:       59.73d {+03h 58m 54s}  +16.12d {+16d 07' 26"}
MOON_DIST:       117.54 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      268.98, 75.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      178.07, 15.09 [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 23 Nov 18 06:03:27 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     873186,   Seg_Num: 0
POINT_RA:        184.367d {+12h 17m 28s} (J2000)
POINT_DEC:       +14.588d {+14d 35' 19"} (J2000)
ROLL:            121.877d
IMG_START_DATE:  18445 TJD;   327 DOY;   18/11/23
IMG_START_TIME:  20279.23 SOD {05:37:59.23} UT,   296.1 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     564644301
X_OFFSET:        725 [pixels]
Y_OFFSET:        984 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       885
Y_GRB_POS:       1144
BINNING_INDEX:   1
IM_URL:          sw00873186000msuni0318.fits
SUN_POSTN:       238.75d {+15h 54m 59s}  -20.33d {-20d 20' 01"}
SUN_DIST:         63.58 [deg]   Sun_angle= 3.6 [hr] (West of Sun)
MOON_POSTN:       59.74d {+03h 58m 57s}  +16.13d {+16d 07' 35"}
MOON_DIST:       117.53 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      268.98, 75.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      178.07, 15.09 [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 23 Nov 18 06:03:43 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     873186,   Seg_Num: 0
POINT_RA:        184.367d {+12h 17m 28s} (J2000)
POINT_DEC:       +14.588d {+14d 35' 19"} (J2000)
ROLL:            121.877d
IMG_START_DATE:  18445 TJD;   327 DOY;   18/11/23
IMG_START_TIME:  20279.23 SOD {05:37:59.23} UT,   296.1 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     564644301
X_OFFSET:        725 [pixels]
Y_OFFSET:        984 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       885
Y_GRB_POS:       1144
BINNING_INDEX:   1
IM_URL:          sw00873186000msuni0318.fits
SUN_POSTN:       238.75d {+15h 54m 59s}  -20.33d {-20d 20' 01"}
SUN_DIST:         63.58 [deg]   Sun_angle= 3.6 [hr] (West of Sun)
MOON_POSTN:       59.74d {+03h 58m 58s}  +16.13d {+16d 07' 37"}
MOON_DIST:       117.53 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      268.98, 75.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      178.07, 15.09 [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:     Fri 23 Nov 18 06:02:59 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     873186,   Seg_Num: 0
GRB_RA:          184.3669d {+12h 17m 28.05s} (J2000),
                 184.6068d {+12h 18m 25.64s} (current),
                 183.7316d {+12h 14m 55.57s} (1950)
GRB_DEC:         +14.5980d {+14d 35' 52.8"} (J2000),
                 +14.4931d {+14d 29' 35.2"} (current),
                 +14.8757d {+14d 52' 32.5"} (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:  18445 TJD;   327 DOY;   18/11/23
IMG_START_TIME:  20100.00 SOD {05:35:00.00} UT,   116.9 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       238.75d {+15h 54m 59s}  -20.33d {-20d 20' 01"}
SUN_DIST:         63.59 [deg]   Sun_angle= 3.6 [hr] (West of Sun)
MOON_POSTN:       59.73d {+03h 58m 56s}  +16.13d {+16d 07' 31"}
MOON_DIST:       117.53 [deg]
MOON_ILLUM:      100 [%]
GAL_COORDS:      268.96, 75.18 [deg] galactic lon,lat of the burst
ECL_COORDS:      178.06, 15.10 [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 #23433
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Using promptly downlinked XRT event data for GRB 181123B, we find an enhanced XRT position of the afterglow: RA, Dec: 184.3670, 14.5979 which is equivalent to:
```
   RA (J2000)  = 12 17 28.08
   Dec (J2000) = +14 35 52.5
```
with an uncertainty of 2.1 arcseconds (radius, 90% confidence). Analysis of the promptly available data is online at http://www.swift.ac.uk/sper/873186.
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 #23434
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team.
Using 987 s of XRT Photon Counting mode data and 2 UVOT images for GRB 181123B, 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 = 184.36687, +14.59789 which is equivalent to:
```
RA (J2000): 12h 17m 28.05s
Dec (J2000): +14d 35' 52.4"
```
with an uncertainty of 1.8 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 #23435
D.N. Burrows (PSU), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. Tohuvavohu (PSU), S. J. LaPorte (PSU) and A.Y. Lien report on behalf of the Swift-XRT team:
We have analysed 6.3 ks of XRT data for GRB 181123B (Lien et al. GCN Circ. 23432), from 95 s to 16.0 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN Circ. 23433).
The light curve can be modelled with a power-law decay with a decay index of alpha=1.31 (+0.15, -0.14).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.99 (+0.30, -0.20). The best-fitting absorption column is 3.9 (+6.4, -0.8) x 10^20 cm^-2, consistent with the Galactic value of 3.1 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 3.2 x 10^-11 (3.6 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     3.9 (+6.4, -0.8) x 10^20 cm^-2
Galactic foreground: 3.1 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.99 (+0.30, -0.20)
```
If the light curve continues to decay with a power-law decay index of 1.31, the count rate at T+24 hours will be 1.9 x 10^-4 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.1 x 10^-15 (6.7 x 10^-15) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00873186.
This circular is an official product of the Swift-XRT team.
GCN Circular #23437
GRB 181123B: Swift/UVOT Upper Limits
S. R. Oates (U.Warwick) and A. Y. Lien (GSFC/UMBC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 181123B 84 s after the BAT trigger (Lien et al., GCN Circ. 23432). No optical afterglow consistent with the XRT position (Osborne et al. GCN Circ. 23434) 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            84          233          147         >20.3
u_FC               296          546          246         >19.5
white               84         6529          727         >21.0
v                  626        10922         1228         >19.8
b                  551         6324          432         >20.1
u                  296         6119          659         >20.1
w1                4278        12566         1113         >20.2
m2                5509        11827         1082         >20.5
w2                5100         6734          393         >19.8
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.03 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #23439
W. Fong (Northwestern Univ.), N. R. Tanvir (U. Leicester) and A. J. Levan (U. Warwick) report on behalf of a larger collaboration:
"We observed the location of the short-duration GRB 181123B (Lien et al., GCN 23432) with the Gemini Multi-Object Spectrograph (GMOS) mounted on the Gemini-North 8-meter telescope. We obtained 18x90-sec each in the i-band at a mid-time of 2018 November 23.618 UT (9.2 hr post-burst). The observations have an airmass range of 1.4-1.9, 0.9” seeing, and were taken in thick, variable clouds. We detect a faint source consistent with the UVOT-enhanced XRT position (Evans et al., GCN 23433; Osborne et al., GCN 23434) at the position:
```
RA(J2000) = 12:17:27.95
Dec(J2000) = +14:35:52.5
+/- 0.05" in each coordinate
```
The source has a preliminary magnitude of i~23.32 +/- 0.25 AB mag, not corrected for Galactic extinction. Both astrometry and photometry are calibrated to SDSS. The source appears to be marginally extended; however, at present it is too weak of a detection to make a strong conclusion.
Further observations are planned. We thank the Gemini staff, and in particular observers Julia Scharwaechter and Michael Hoenig, for their assistance with these observations."
GCN Circular #23440
K. Paterson and W. Fong (Northwestern) report:
"We observed the field of the short-duration GRB 181123B (Lien et al., GCN 23432) with the Multi-Object Spectrometer For Infra-Red Exploration (MOSFIRE) mounted on the 10-m Keck I telescope, starting on 2018 November 23 at 14:43:18 UT, 9.2 hours post-burst. We obtained 2100-sec of observations in the J-band in 1.0" seeing.
In our combined stack, we identify a near-IR source consistent with the X-ray position of the afterglow (Evans et al., GCN 23433; Osborne et al., GCN 23434) and the Gemini optical source (Fong et al., GCN 23439). Calibrated to 2MASS, we estimate a preliminary brightness of J(AB) = 22.94 +/- 0.19 mag. At this point it is not possible to tell whether this source is point-like or extended.
We thank the Keck Observatory staff, in particular Arina, Joel, Alessandro, Josh and Randy, for their assistance with planning and executing these observations."
GCN Circular #23441
D. M. Palmer (LANL), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), T. Sakamoto (AGU), M. Stamatikos (OSU), 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 181123B (trigger #873186) (Lien et al., GCN Circ. 23432). The BAT ground-calculated position is RA, Dec = 184.354, 14.619 deg which is
```
  RA(J2000)  =  12h 17m 25.0s
  Dec(J2000) = +14d 37' 08.7"
```
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment). The partial coding was 59%.
The mask-weighted light curve shows a short pulse that starts at ~T0, peaks at ~T+0.1 s, and ends at ~T+0.3 s. T90 (15-350 keV) is 0.26 +- 0.04 sec (estimated error including systematics).
The time-averaged spectrum from T+0.03 to T+0.31 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 0.72 +- 0.28. The fluence in the 15-150 keV band is 1.2 +- 0.2 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T-0.33 sec in the 15-150 keV band is 1.3 +- 0.3 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/873186/BA/
GCN Circular #23443
J. P. Norris (BSU), S. D. Barthelmy (GSFC), A. Y. Lien (GSFC/UMBC) report:
We report the spectral lag analysis and the search for extended emission for GRB 181123B (Lien et al., GCN Circ. 23432).
Using the 8-ms binned light curve, the spectral lag of the short pulse is 6 (+11, -11) ms for the 100-350 keV to 25-50 keV bands, and 10 (+14, -11) ms for the 50-100 keV to 15-25 keV bands. These lag values are consistent with a short GRB.
The Bayesian block analysis using the mask-tagged light curves suggests that there may be a marginal (~ 3 sigma) extended emission that lasts until ~T+60 s.
GCN Circular #23444
V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa,A.Kuznetsov, V.V.Chazov, D. Vlasenko Lomonosov Moscow State University, Sternberg Astronomical Institute
R. Podesta, F. Podesta, C. Lopez, C.Francile Observatorio Astronomico Felix Aguilar (OAFA)
Hugo Levato Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)
R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias
D. Buckley, South African Astronomical Observatory
A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory
O. Gres, N.M. Budnev, Yu.Ishmuhametova Applied Physics Institute of Irkutsk State University
V. Yurkov, A. Gabovich, Yu. Sergienko Blagoveschensk Educational State University, Blagoveschensk
MASTER-OAFA robotic telescope (MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) was pointed to the GRB181123B (Lien et al.,GCN 23432) at 2018-11-23 08:15:00 UT. On our 4-th (180s exposure) set we not found optical transient within Swift error-box (ra=184.367 dec=14.5975 r=0.05) brighter than 17.0.
The galactic latitude b = -60 deg., longitude l = 98 deg. The observations made on zenit distance = 32 deg.The moon ( 1 % bright part) below the horizon (The altitude of the Moon is -44 deg. ). The sun altitude is -50.0 deg. The object can be observed till 2018-10-10 09:24:14
MASTER-Kislovodsk robotic telescope (MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the GRB181123B (Lien et al., GCN 23432) 63194 sec after notice time and 63194 sec after trigger time at 2018-11-23 23:06:17 UT. On our 10-th (180s exposure) set , obtained 72767 sec after tigger time at 2018-11-24 01:45:51 UT, we not found optical transient within Swift error-box (ra=184.367 dec=14.5975 r=0.05) brighter than 18.1.
The galactic latitude b = 75 deg., longitude l = 272 deg. The observations made on zenit distance = 53 deg.The moon (99 % bright part) is 34 deg. above the horizon. The distance between moon and object is 106 The sun altitude is -26.2 deg. The object can be observed till sunrise at 2018-11-24 04:14:26
GCN Circular #23452
Q. B. Yi, C. K. Li, X. B. Li, G. Li, J. Y. Liao, S. L. Xiong, C. Z. Liu, X. F. Li, Z. W. Li, Z. Chang, X. F. Lu, J. L. Zhao, A. M. Zhang, Y. F. Zhang, C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, H. Y. Wang, M. Wu, Y. P. Xu, S. N. Zhang (IHEP), report on behalf of the Insight-HXMT team:
At 2018-11-23T05:33:03.09 (T0), the Insight-HXMT/HE detected GRB 181123B (trigger ID: HEB181123231) in a routine search of the data, which was also detected by the SWIFT/BAT (J. P. Norris et al. 2018, GCN 23443)
The Insight-HXMT/HE light curve mainly consists of a pulse with a duration (T90) of 0.23 s measured from T0+0.16 s. The 50-ms peak rate, measured from T0+0.28 s, is 5091.4 cnts/s. The total counts from this burst is 2060.5 counts. URL_LC: http://www.hxmt.org/images/GRB/HEB181123231_lc.jpg
All measurements above are made with the CsI detectors operating in the regular mode with the energy range of about 80-800 keV (record energy). Only gamma-rays with energy greater than about 200 keV can penetrate the spacecraft and leave signals in the CsI detectors installed inside of the telescope.
Insight-HXMT is the first Chinese space X-ray telescope, which was fundedjointly by the China National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS). More information could be found at: http://www.hxmt.org.
GCN Circular #23461
K. Paterson, W. Fong (Northwestern), K. De (Caltech), K. Alexander, D. Coppejans, A. Hajela, R. Margutti, and G. Terreran (Northwestern) report:
"We observed the field of the short-duration GRB 181123B (Lien et al., GCN 23432) with the Multi-Object Spectrometer For Infra-Red Exploration (MOSFIRE) mounted on the 10-m Keck I telescope, starting on 2018 November 26 at 14:57:43 UT, 1.94 days after our previous MOSFIRE observations (Paterson et al. GCN 23440) and 3.38 days after the burst. We obtained 2142-sec of observations in the J-band in 0.7" seeing and clear conditions.
We detect a NIR source that is clearly extended, with a brightness and position consistent with our previous observations (Paterson et al. GCN 23440) and with the Gemini optical source position (Fong et al. GCN 23439). Image subtraction between our MOSFIRE observations also yields no residuals in or around the XRT position (Evans et al. GCN 23433; Osborne et al. GCN 23434) or the position of the optical source. Given the lack of residuals and the extended nature of the NIR source, we propose this as the host galaxy of GRB 181123B. We also place a 3-sigma upper limit of J>23.3 mag (AB, for epoch 1 at 9.2 hr post-burst) on afterglow emission from GRB 181123B.
We thank the Keck staff for their assistance with these ToO observations."
GCN Circular #23467
G. E. Anderson (Curtin), M. E. Bell (UTS), J. Stevens (CASS), P. J. Hancock (Curtin), J. C. A. Miller-Jones (Curtin), A. Bahramian (Curtin), K. W. Bannister (CASS), A. J, van der Horst (GWU), S. D. Ryder (Macquarie), J-P. Macquart (Curtin), R. M. Plotkin (Curtin), A. Rowlinson (UvA)
We used the Australia Telescope Compact Array (ATCA) rapid-response mode to perform a triggered radio observation of the short GRB 181123B. The ATCA responded to the Swift-BAT detection (Lien et al., GCN 23432), automatically scheduling observations to begin on 2018 Nov 23.753 UT for 8.5 hours (12.5 hours post-burst), when the GRB had risen above the horizon. No radio source was detected at the XRT/optical position (Evans et al., GCN 23433, Fong et al., GCN 23439), with 3 sigma upper-limits of 66 microJy and 69 microJy at 5 and 9 GHz, respectively.
We thank the ATCA and CSIRO Astronomy and Space Science (CASS) staff for supporting this new mode of operation.
Afterglow and host (with redshift 1.754)
https://iopscience.iop.org/article/10.3847/2041-8213/aba4b0

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