Gamma-ray Burst 180823A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 23 Aug 18 19:05:10 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     855434,   Seg_Num: 0
GRB_RA:          210.349d {+14h 01m 24s} (J2000),
                 210.574d {+14h 02m 18s} (current),
                 209.746d {+13h 58m 59s} (1950)
GRB_DEC:         +14.884d {+14d 53' 03"} (J2000),
                 +14.795d {+14d 47' 41"} (current),
                 +15.125d {+15d 07' 31"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       15854 [cnts]    Image_Peak=444 [image_cnts]
TRIGGER_DUR:     2.048 [sec] 
TRIGGER_INDEX:   262     E_range: 25-100 keV
BKG_INTEN:       174093 [cnts]
BKG_TIME:        68642.52 SOD {19:04:02.52} UT
BKG_DUR:         24 [sec]
GRB_DATE:        18353 TJD;   235 DOY;   18/08/23
GRB_TIME:        68672.98 SOD {19:04:32.98} UT
GRB_PHI:         -24.35 [deg]
GRB_THETA:        25.02 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     11.74 [sigma]
IMAGE_SIGNIF:    8.89 [sigma]
MERIT_PARAMS:     +1  +0  +0  +1  +2  -1  +0  +0 -55  +0 
SUN_POSTN:       152.66d {+10h 10m 40s}  +11.26d {+11d 15' 28"}
SUN_DIST:         56.38 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:      303.27d {+20h 13m 04s}  -19.41d {-19d 24' 48"}
MOON_DIST:        97.34 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      359.51, 69.63 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      202.52, 25.46 [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 = 4.44,-20.50 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 23 Aug 18 19:06:38 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     855434,   Seg_Num: 0
GRB_RA:          210.3568d {+14h 01m 25.6s} (J2000),
                 210.5817d {+14h 02m 19.6s} (current),
                 209.7537d {+13h 59m 00.8s} (1950)
GRB_DEC:         +14.8914d {+14d 53' 29.0"} (J2000),
                 +14.8019d {+14d 48' 06.9"} (current),
                 +15.1324d {+15d 07' 56.5"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       87 [cnts]
IMG_START_DATE:  18353 TJD;   235 DOY;   18/08/23
IMG_START_TIME:  68762.20 SOD {19:06:02.20} UT,   89.2 [sec] since BAT Trigger Time
CENTROID_X:      323.73,  raw= 324  [pixels]
CENTROID_Y:      276.07,  raw= 276  [pixels]
ROLL:            273.74 [deg]
GAIN:            2
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -52.62
GRB_POS_XRT_Z:   40.86
IMAGE_URL:       sw00855434000msxps_rw.img
SUN_POSTN:       152.67d {+10h 10m 40s}  +11.26d {+11d 15' 27"}
SUN_DIST:         56.39 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:      303.28d {+20h 13m 07s}  -19.41d {-19d 24' 42"}
MOON_DIST:        97.34 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      359.54, 69.63 [deg] galactic lon,lat of the burst
ECL_COORDS:      202.53, 25.47 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.  
COMMENTS:        The object found at this position is either a very bright burst or a cosmic ray hit.  
COMMENTS:        Examine the XRT Image to differentiate (CRs are much more compact); see examples at:  
COMMENTS:        http://www.swift.psu.edu/xrt/XRT_Postage_Stamp_Image_Photo_Gallery.htm .

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 23 Aug 18 19:06:41 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     855434,   Seg_Num: 0
GRB_RA:          210.3568d {+14h 01m 25.6s} (J2000),
                 210.5817d {+14h 02m 19.6s} (current),
                 209.7537d {+13h 59m 00.8s} (1950)
GRB_DEC:         +14.8914d {+14d 53' 29.0"} (J2000),
                 +14.8019d {+14d 48' 06.9"} (current),
                 +15.1324d {+15d 07' 56.5"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       87 [cnts]
IMG_START_DATE:  18353 TJD;   235 DOY;   18/08/23
IMG_START_TIME:  68762.20 SOD {19:06:02.20} UT,   89.2 [sec] since BAT Trigger Time
CENTROID_X:      323.73,  raw= 324  [pixels]
CENTROID_Y:      276.07,  raw= 276  [pixels]
ROLL:            273.74 [deg]
GAIN:            2
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -52.62
GRB_POS_XRT_Z:   40.86
IMAGE_URL:       sw00855434000msxps_rw.img
SUN_POSTN:       152.67d {+10h 10m 40s}  +11.26d {+11d 15' 27"}
SUN_DIST:         56.39 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:      303.28d {+20h 13m 07s}  -19.41d {-19d 24' 42"}
MOON_DIST:        97.34 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      359.54, 69.63 [deg] galactic lon,lat of the burst
ECL_COORDS:      202.53, 25.47 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.  
COMMENTS:        The object found at this position is either a very bright burst or a cosmic ray hit.  
COMMENTS:        Examine the XRT Image to differentiate (CRs are much more compact); see examples at:  
COMMENTS:        http://www.swift.psu.edu/xrt/XRT_Postage_Stamp_Image_Photo_Gallery.htm .

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 23 Aug 18 19:06:28 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     855434,   Seg_Num: 0
GRB_RA:          210.3568d {+14h 01m 25.63s} (J2000),
                 210.5817d {+14h 02m 19.61s} (current),
                 209.7537d {+13h 59m 00.88s} (1950)
GRB_DEC:         +14.8914d {+14d 53' 29.0"} (J2000),
                 +14.8019d {+14d 48' 06.9"} (current),
                 +15.1324d {+15d 07' 56.5"} (1950)
GRB_ERROR:       5.0 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       3.10e-09 [erg/cm2/sec]
GRB_SIGNIF:      9.32 [sigma]
IMG_START_DATE:  18353 TJD;   235 DOY;   18/08/23
IMG_START_TIME:  68762.20 SOD {19:06:02.20} UT,   89.2 [sec] since BAT Trigger Time
TAM[0-3]:        327.69 237.21 261.75 243.66
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       152.67d {+10h 10m 40s}  +11.26d {+11d 15' 27"}
SUN_DIST:         56.39 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:      303.28d {+20h 13m 07s}  -19.41d {-19d 24' 43"}
MOON_DIST:        97.34 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      359.54, 69.63 [deg] galactic lon,lat of the burst
ECL_COORDS:      202.53, 25.47 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 0.62 arcmin from the BAT position.  
COMMENTS:        The object found at this position is either a very bright burst or a cosmic ray hit.  
COMMENTS:        Examine the XRT Image to differentiate (CRs are much more compact); see examples at:  
COMMENTS:        http://www.swift.psu.edu/xrt/XRT_Postage_Stamp_Image_Photo_Gallery.htm .

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 23 Aug 18 19:08:10 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     855434,   Seg_Num: 0
GRB_RA:          210.349d {+14h 01m 24s} (J2000),
                 210.574d {+14h 02m 18s} (current),
                 209.746d {+13h 58m 59s} (1950)
GRB_DEC:         +14.884d {+14d 53' 03"} (J2000),
                 +14.795d {+14d 47' 41"} (current),
                 +15.125d {+15d 07' 31"} (1950)
GRB_DATE:        18353 TJD;   235 DOY;   18/08/23
GRB_TIME:        68672.98 SOD {19:04:32.98} UT
TRIGGER_INDEX:   262
GRB_PHI:         -24.35 [deg]
GRB_THETA:        25.02 [deg]
DELTA_TIME:      -5.00 [sec]
TRIGGER_DUR:     2.048 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     11.74 [sigma]
IMAGE_SIGNIF:    8.89 [sigma]
LC_URL:          sw00855434000msb.lc
SUN_POSTN:       152.67d {+10h 10m 40s}  +11.26d {+11d 15' 26"}
SUN_DIST:         56.38 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:      303.29d {+20h 13m 10s}  -19.41d {-19d 24' 36"}
MOON_DIST:        97.36 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      359.51, 69.63 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      202.52, 25.46 [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 = 4.44,-20.50 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 23 Aug 18 19:23:12 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     855434,   Seg_Num: 0
POINT_RA:        210.345d {+14h 01m 23s} (J2000)
POINT_DEC:       +14.876d {+14d 52' 34"} (J2000)
POINT_ROLL:      273.739d
IMG_START_DATE:  18353 TJD;   235 DOY;   18/08/23
IMG_START_TIME:  69052.76 SOD {19:10:52.76} UT,   379.8 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        0.753
N_STARS:         9
X_OFFSET:        482 [pixels]
Y_OFFSET:        622 [pixels]
X_MAX:           1441 [pixels]
Y_MAX:           1581 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    3
SL_URL:          sw00855434000msufc0379.fits
SUN_POSTN:       152.68d {+10h 10m 42s}  +11.25d {+11d 15' 13"}
SUN_DIST:         56.37 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:      303.42d {+20h 13m 41s}  -19.39d {-19d 23' 39"}
MOON_DIST:        97.48 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      359.48, 69.63 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      202.52, 25.45 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 23 Aug 18 19:23:22 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     855434,   Seg_Num: 0
POINT_RA:        210.345d {+14h 01m 23s} (J2000)
POINT_DEC:       +14.876d {+14d 52' 34"} (J2000)
POINT_ROLL:      273.739d
IMG_START_DATE:  18353 TJD;   235 DOY;   18/08/23
IMG_START_TIME:  69052.76 SOD {19:10:52.76} UT,   379.8 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        0.753
N_STARS:         9
X_OFFSET:        482 [pixels]
Y_OFFSET:        622 [pixels]
X_MAX:           1441 [pixels]
Y_MAX:           1581 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    3
SL_URL:          sw00855434000msufc0379.fits
SUN_POSTN:       152.68d {+10h 10m 42s}  +11.25d {+11d 15' 13"}
SUN_DIST:         56.37 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:      303.42d {+20h 13m 42s}  -19.39d {-19d 23' 38"}
MOON_DIST:        97.48 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      359.48, 69.63 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      202.52, 25.45 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        If you have elected to receive attachments:  
COMMENTS:        The uvot_catalog_srclist.fits.gz file does not exist; skipping the attachment.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 23 Aug 18 19:24:48 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     855434,   Seg_Num: 0
POINT_RA:        210.345d {+14h 01m 23s} (J2000)
POINT_DEC:       +14.876d {+14d 52' 34"} (J2000)
ROLL:            273.739d
IMG_START_DATE:  18353 TJD;   235 DOY;   18/08/23
IMG_START_TIME:  69052.76 SOD {19:10:52.76} UT,   379.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     556744274
X_OFFSET:        801 [pixels]
Y_OFFSET:        941 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       961
Y_GRB_POS:       1101
BINNING_INDEX:   1
IM_URL:          sw00855434000msuni0401.fits
SUN_POSTN:       152.68d {+10h 10m 43s}  +11.25d {+11d 15' 12"}
SUN_DIST:         56.37 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:      303.44d {+20h 13m 45s}  -19.39d {-19d 23' 33"}
MOON_DIST:        97.49 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      359.48, 69.63 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      202.52, 25.45 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 23 Aug 18 19:25:02 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     855434,   Seg_Num: 0
POINT_RA:        210.345d {+14h 01m 23s} (J2000)
POINT_DEC:       +14.876d {+14d 52' 34"} (J2000)
ROLL:            273.739d
IMG_START_DATE:  18353 TJD;   235 DOY;   18/08/23
IMG_START_TIME:  69052.76 SOD {19:10:52.76} UT,   379.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     556744274
X_OFFSET:        801 [pixels]
Y_OFFSET:        941 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       961
Y_GRB_POS:       1101
BINNING_INDEX:   1
IM_URL:          sw00855434000msuni0401.fits
SUN_POSTN:       152.68d {+10h 10m 43s}  +11.25d {+11d 15' 11"}
SUN_DIST:         56.37 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:      303.44d {+20h 13m 45s}  -19.39d {-19d 23' 32"}
MOON_DIST:        97.49 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      359.48, 69.63 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      202.52, 25.45 [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:        If you have elected to receive attachments:  
COMMENTS:        The uvot_catalog_image.fits.gz file does not exist; skipping the attachment.

GCN Circular #23169
B. Sbarufatti (PSU), H. A. Krimm (NSF/USRA), F. E. Marshall (NASA/GSFC) and A. Tohuvavohu (PSU) report on behalf of the Neil Gehrels Swift Observatory Team:
At 19:04:32 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 180823A (trigger=855434). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 210.349, +14.884 which is
```
   RA(J2000) = 14h 01m 24s
   Dec(J2000) = +14d 53' 03"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve, which is superimposed on a declining background, shows a double-peaked structure with a duration of about 40 sec. The peak count rate was ~2000 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 19:06:02.2 UT, 89.2 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 210.35630, 14.89029 which is equivalent to:
```
   RA(J2000)  = 14h 01m 25.51s
   Dec(J2000) = +14d 53' 25.0"
```
with an uncertainty of 5.4 arcseconds (radius, 90% containment). This location is 34 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 3.10e-09 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 37 seconds with the White filter starting 379 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 is expected to be about 18.5 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.02.
Burst Advocate for this burst is B. Sbarufatti (bxs60 AT psu.edu). 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:     Thu 23 Aug 18 19:36:01 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     855434,   Seg_Num: 0
GRB_RA:          210.3563d {+14h 01m 25.51s} (J2000),
                 210.5812d {+14h 02m 19.49s} (current),
                 209.7532d {+13h 59m 00.76s} (1950)
GRB_DEC:         +14.8902d {+14d 53' 24.7"} (J2000),
                 +14.8007d {+14d 48' 02.6"} (current),
                 +15.1312d {+15d 07' 52.2"} (1950)
GRB_ERROR:       5.4 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  18353 TJD;   235 DOY;   18/08/23
IMG_START_TIME:  69053.00 SOD {19:10:53.00} UT,   380.0 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       152.68d {+10h 10m 44s}  +11.25d {+11d 15' 02"}
SUN_DIST:         56.37 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:      303.53d {+20h 14m 08s}  -19.38d {-19d 22' 49"}
MOON_DIST:        97.57 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      359.53, 69.63 [deg] galactic lon,lat of the burst
ECL_COORDS:      202.53, 25.47 [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:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.11% < P(seren) < 0.58%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 23 Aug 18 20:11:10 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     855434,   Seg_Num: 0
POINT_RA:        210.370d {+14h 01m 29s} (J2000)
POINT_DEC:       +14.947d {+14d 56' 50"} (J2000)
POINT_ROLL:      273.824d
IMG_START_DATE:  18353 TJD;   235 DOY;   18/08/23
IMG_START_TIME:  72379.42 SOD {20:06:19.42} UT,   3706.4 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        7.264
N_STARS:         12
X_OFFSET:        346 [pixels]
Y_OFFSET:        80 [pixels]
X_MAX:           1305 [pixels]
Y_MAX:           1039 [pixels]
DET_THRESH:      23
PHOTO_THRESH:    14
SL_URL:          sw00855434000msufc3706.fits
SUN_POSTN:       152.71d {+10h 10m 50s}  +11.24d {+11d 14' 32"}
SUN_DIST:         56.36 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:      303.84d {+20h 15m 21s}  -19.34d {-19d 20' 32"}
MOON_DIST:        97.85 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      359.68, 69.66 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      202.52, 25.53 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 23 Aug 18 20:11:27 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     855434,   Seg_Num: 0
POINT_RA:        210.370d {+14h 01m 29s} (J2000)
POINT_DEC:       +14.947d {+14d 56' 50"} (J2000)
POINT_ROLL:      273.824d
IMG_START_DATE:  18353 TJD;   235 DOY;   18/08/23
IMG_START_TIME:  72379.42 SOD {20:06:19.42} UT,   3706.4 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        7.264
N_STARS:         12
X_OFFSET:        346 [pixels]
Y_OFFSET:        80 [pixels]
X_MAX:           1305 [pixels]
Y_MAX:           1039 [pixels]
DET_THRESH:      23
PHOTO_THRESH:    14
SL_URL:          sw00855434000msufc3706.fits
SUN_POSTN:       152.71d {+10h 10m 50s}  +11.24d {+11d 14' 32"}
SUN_DIST:         56.36 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:      303.84d {+20h 15m 22s}  -19.34d {-19d 20' 31"}
MOON_DIST:        97.85 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      359.68, 69.66 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      202.52, 25.53 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 23 Aug 18 20:12:41 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     855434,   Seg_Num: 0
POINT_RA:        210.370d {+14h 01m 29s} (J2000)
POINT_DEC:       +14.947d {+14d 56' 50"} (J2000)
ROLL:            273.824d
IMG_START_DATE:  18353 TJD;   235 DOY;   18/08/23
IMG_START_TIME:  72379.42 SOD {20:06:19.42} UT,   3706.4 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     556747600
X_OFFSET:        665 [pixels]
Y_OFFSET:        399 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       825
Y_GRB_POS:       559
BINNING_INDEX:   1
IM_URL:          sw00855434000msuni3728.fits
SUN_POSTN:       152.71d {+10h 10m 50s}  +11.24d {+11d 14' 31"}
SUN_DIST:         56.36 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:      303.85d {+20h 15m 24s}  -19.34d {-19d 20' 26"}
MOON_DIST:        97.86 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      359.68, 69.66 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      202.52, 25.53 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 23 Aug 18 20:11:46 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     855434,   Seg_Num: 0
GRB_RA:          210.3562d {+14h 01m 25.48s} (J2000),
                 210.5811d {+14h 02m 19.46s} (current),
                 209.7531d {+13h 59m 00.73s} (1950)
GRB_DEC:         +14.8902d {+14d 53' 24.7"} (J2000),
                 +14.8007d {+14d 48' 02.6"} (current),
                 +15.1312d {+15d 07' 52.2"} (1950)
GRB_ERROR:       4.5 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  18353 TJD;   235 DOY;   18/08/23
IMG_START_TIME:  69053.00 SOD {19:10:53.00} UT,   380.0 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       152.71d {+10h 10m 50s}  +11.24d {+11d 14' 32"}
SUN_DIST:         56.35 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:      303.84d {+20h 15m 22s}  -19.34d {-19d 20' 30"}
MOON_DIST:        97.85 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      359.53, 69.63 [deg] galactic lon,lat of the burst
ECL_COORDS:      202.53, 25.47 [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:     Thu 23 Aug 18 20:12:53 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     855434,   Seg_Num: 0
POINT_RA:        210.370d {+14h 01m 29s} (J2000)
POINT_DEC:       +14.947d {+14d 56' 50"} (J2000)
ROLL:            273.824d
IMG_START_DATE:  18353 TJD;   235 DOY;   18/08/23
IMG_START_TIME:  72379.42 SOD {20:06:19.42} UT,   3706.4 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     556747600
X_OFFSET:        665 [pixels]
Y_OFFSET:        399 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       825
Y_GRB_POS:       559
BINNING_INDEX:   1
IM_URL:          sw00855434000msuni3728.fits
SUN_POSTN:       152.71d {+10h 10m 50s}  +11.24d {+11d 14' 31"}
SUN_DIST:         56.36 [deg]   Sun_angle= -3.9 [hr] (East of Sun)
MOON_POSTN:      303.85d {+20h 15m 25s}  -19.34d {-19d 20' 26"}
MOON_DIST:        97.86 [deg]
MOON_ILLUM:      94 [%]
GAL_COORDS:      359.68, 69.66 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      202.52, 25.53 [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 #23170
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team.
Using 2364 s of XRT Photon Counting mode data and 7 UVOT images for GRB 180823A, 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 = 210.35583, +14.89245 which is equivalent to:
```
RA (J2000): 14h 01m 25.40s
Dec (J2000): +14d 53' 32.8"
```
with an uncertainty of 1.6 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177).
This circular was automatically generated, and is an official product of the Swift-XRT team.
GCN Circular #23171
A. Tohuvavohu (PSU), S. J. LaPorte (PSU), S.L. Gibson (U. Leicester), Z. Liu (NAOC / U. Leicester), J.P. Osborne (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), J.A. Kennea (PSU) and B. Sbarufatti report on behalf of the Swift-XRT team:
We have analysed 7.7 ks of XRT data for GRB 180823A (Sbarufatti et al. GCN Circ. 23169), from 331 s to 39.4 ks after the BAT trigger. The data comprise 46 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Goad et al. (GCN Circ. 23170).
The light curve can be modelled with a power-law decay with a decay index of alpha=1.00 (+/-0.04).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.99 (+0.19, -0.18). The best-fitting absorption column is 1.2 (+/-0.5) x 10^21 cm^-2, in excess of the Galactic value of 1.2 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 (4.2 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     1.2 (+/-0.5) x 10^21 cm^-2
Galactic foreground: 1.2 x 10^20 cm^-2
Excess significance: 3.7 sigma
Photon index:	     1.99 (+0.19, -0.18)
```
If the light curve continues to decay with a power-law decay index of 1.00, the count rate at T+24 hours will be 0.013 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.3 x 10^-13 (5.3 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/00855434.
This circular is an official product of the Swift-XRT team.
GCN Circular #23172
Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), Jes�s Gonz�lez (UNAM), Carlos Rom�n-Z��iga (UNAM), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.), and Vicki Toy (UMD) report:
We observed the field of GRB 180823A (Sbarufatti, et al., GCN 23169) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astron�mico Nacional on Sierra San Pedro M�rtir from 2018/08 24.14 to 2018/08 24.19 UTC (8.40 to 9.45 hours after the BAT trigger), obtaining a total of 0.40 hours exposure in the r and i bands and 0.29 hours exposure in the Z, Y, J, and H bands.
For a source within the Swift-XRT error circle (Evans, et al., GCN 23170), in comparison with the SDSS DR9 and 2MASS catalogs, we obtain the following upper limits (3-sigma):
```
 r > 22.20
 i > 22.05
 Z > 20.84
 Y > 19.72
 J > 20.45
 H > 19.12
```
These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB.
We thank the staff of the Observatorio Astron�mico Nacional in San Pedro M�rtir.
GCN Circular #23173
GRB 180823A: Swift/UVOT Upper Limits
S. Sebzda (PSU) and B. Sbarufatti (PSU) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 180823A 381 s after the BAT trigger (Sbarufatti et al., GCN Circ. 23169). No optical afterglow consistent with the XRT position (Goad et al. GCN Circ. 23170) 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 initial exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white              381          417           36         >19.1
white              381         4476          380         >20.9
v                 4686        10356          927         >19.2
b                 4071         4271          197         >19.7
u                 3866         4066          197         >19.8
m2               10361        10803          435         >19.8
w2                4482         4681          197         >20.0
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.02 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #23175
A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), B. Sbarufatti (PSU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-43 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 180823A (trigger #855434) (Sbarufatti, et al., GCN Circ. 23169). The BAT ground-calculated position is RA, Dec = 210.358, 14.901 deg which is
```
  RA(J2000)  =  14h 01m 25.9s 
  Dec(J2000) = +14d 54' 03.2" 
```
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 92%.
The available data starts as the burst is rising, but it appears that it includes the entire burst. The mask-weighted light curve shows a double-peaked structure, starting at ~T-43 seconds, with comparably sized peaks at ~T+5 and ~T+20 sec, and returning to near background by T+70 seconds, with a fainter tail out past T+100 seconds. A spacecraft slew took the burst location out of the BAT field of view around T+450 seconds. T90 (15-350 keV) is 80.3 +- 6.9 sec (estimated error including systematics).
The time-averaged spectrum from T-37.5 to T+72.0 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.58 +- 0.05. The fluence in the 15-150 keV band is 7.8 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+18.33 sec in the 15-150 keV band is 2.3 +- 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/855434/BA/

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Jochen Greiner, last update: 25-Aug-2018 [Disclaimer]