Gamma-ray Burst 180930A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 30 Sep 18 12:44:14 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     864584,   Seg_Num: 0
GRB_RA:           76.870d {+05h 07m 29s} (J2000),
                  77.063d {+05h 08m 15s} (current),
                  76.357d {+05h 05m 26s} (1950)
GRB_DEC:         -25.138d {-25d 08' 17"} (J2000),
                 -25.115d {-25d 06' 52"} (current),
                 -25.203d {-25d 12' 09"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       3129 [cnts]    Image_Peak=157 [image_cnts]
TRIGGER_DUR:     1.024 [sec] 
TRIGGER_INDEX:   137     E_range: 15-50 keV
BKG_INTEN:       19745 [cnts]
BKG_TIME:        45810.32 SOD {12:43:30.32} UT
BKG_DUR:         8 [sec]
GRB_DATE:        18391 TJD;   273 DOY;   18/09/30
GRB_TIME:        45829.26 SOD {12:43:49.26} UT
GRB_PHI:         -167.58 [deg]
GRB_THETA:        26.79 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     11.18 [sigma]
IMAGE_SIGNIF:    7.59 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +1  -2  +0  +0 +28  +0 
SUN_POSTN:       186.71d {+12h 26m 51s}   -2.90d {-02d 54' 03"}
SUN_DIST:        106.42 [deg]   Sun_angle= 7.3 [hr] (West of Sun)
MOON_POSTN:       72.32d {+04h 49m 16s}  +18.49d {+18d 29' 28"}
MOON_DIST:        43.85 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      226.55,-33.14 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       72.18,-47.77 [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 = 133.40,-19.32 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 30 Sep 18 12:47:17 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     864584,   Seg_Num: 0
GRB_RA:           76.870d {+05h 07m 29s} (J2000),
                  77.063d {+05h 08m 15s} (current),
                  76.357d {+05h 05m 26s} (1950)
GRB_DEC:         -25.138d {-25d 08' 17"} (J2000),
                 -25.115d {-25d 06' 52"} (current),
                 -25.203d {-25d 12' 09"} (1950)
GRB_DATE:        18391 TJD;   273 DOY;   18/09/30
GRB_TIME:        45829.26 SOD {12:43:49.26} UT
TRIGGER_INDEX:   137
GRB_PHI:         -167.58 [deg]
GRB_THETA:        26.79 [deg]
DELTA_TIME:      26.00 [sec]
TRIGGER_DUR:     1.024 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     11.18 [sigma]
IMAGE_SIGNIF:    7.59 [sigma]
LC_URL:          sw00864584000msb.lc
SUN_POSTN:       186.72d {+12h 26m 52s}   -2.90d {-02d 54' 05"}
SUN_DIST:        106.42 [deg]   Sun_angle= 7.3 [hr] (West of Sun)
MOON_POSTN:       72.35d {+04h 49m 23s}  +18.50d {+18d 29' 47"}
MOON_DIST:        43.85 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      226.55,-33.14 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       72.18,-47.77 [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 = 133.40,-19.32 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 30 Sep 18 12:47:29 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     864584,   Seg_Num: 0
POINT_RA:         76.868d {+05h 07m 28s} (J2000)
POINT_DEC:       -25.137d {-25d 08' 12"} (J2000)
IMG_START_DATE:  18391 TJD;   273 DOY;   18/09/30
IMG_START_TIME:  46037.65 SOD {12:47:17.65} UT,   208.4 [sec] since BAT Trigger Time
COUNTS:          17    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:     Sun 30 Sep 18 12:50:14 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     864584,   Seg_Num: 0
POINT_RA:         76.868d {+05h 07m 28s} (J2000)
POINT_DEC:       -25.137d {-25d 08' 13"} (J2000)
POINT_ROLL:      101.422d
IMG_START_DATE:  18391 TJD;   273 DOY;   18/09/30
IMG_START_TIME:  46041.12 SOD {12:47:21.12} UT,   211.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.561
N_STARS:         59
X_OFFSET:        496 [pixels]
Y_OFFSET:        529 [pixels]
X_MAX:           1455 [pixels]
Y_MAX:           1488 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00864584000msufc0211.fits
SUN_POSTN:       186.72d {+12h 26m 52s}   -2.90d {-02d 54' 08"}
SUN_DIST:        106.42 [deg]   Sun_angle= 7.3 [hr] (West of Sun)
MOON_POSTN:       72.37d {+04h 49m 30s}  +18.50d {+18d 30' 05"}
MOON_DIST:        43.85 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      226.55,-33.15 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       72.18,-47.77 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 30 Sep 18 12:50:31 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     864584,   Seg_Num: 0
POINT_RA:         76.868d {+05h 07m 28s} (J2000)
POINT_DEC:       -25.137d {-25d 08' 13"} (J2000)
POINT_ROLL:      101.422d
IMG_START_DATE:  18391 TJD;   273 DOY;   18/09/30
IMG_START_TIME:  46041.12 SOD {12:47:21.12} UT,   211.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.561
N_STARS:         59
X_OFFSET:        496 [pixels]
Y_OFFSET:        529 [pixels]
X_MAX:           1455 [pixels]
Y_MAX:           1488 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00864584000msufc0211.fits
SUN_POSTN:       186.72d {+12h 26m 52s}   -2.90d {-02d 54' 09"}
SUN_DIST:        106.42 [deg]   Sun_angle= 7.3 [hr] (West of Sun)
MOON_POSTN:       72.38d {+04h 49m 31s}  +18.50d {+18d 30' 06"}
MOON_DIST:        43.85 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      226.55,-33.15 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       72.18,-47.77 [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:     Sun 30 Sep 18 12:51:33 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     864584,   Seg_Num: 0
POINT_RA:         76.868d {+05h 07m 28s} (J2000)
POINT_DEC:       -25.137d {-25d 08' 13"} (J2000)
ROLL:            101.422d
IMG_START_DATE:  18391 TJD;   273 DOY;   18/09/30
IMG_START_TIME:  46041.12 SOD {12:47:21.12} UT,   211.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     560004462
X_OFFSET:        815 [pixels]
Y_OFFSET:        848 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       975
Y_GRB_POS:       1008
BINNING_INDEX:   1
IM_URL:          sw00864584000msuni0233.fits
SUN_POSTN:       186.72d {+12h 26m 53s}   -2.90d {-02d 54' 10"}
SUN_DIST:        106.42 [deg]   Sun_angle= 7.3 [hr] (West of Sun)
MOON_POSTN:       72.39d {+04h 49m 33s}  +18.50d {+18d 30' 13"}
MOON_DIST:        43.85 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      226.55,-33.15 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       72.18,-47.77 [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:     Sun 30 Sep 18 12:51:47 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     864584,   Seg_Num: 0
POINT_RA:         76.868d {+05h 07m 28s} (J2000)
POINT_DEC:       -25.137d {-25d 08' 13"} (J2000)
ROLL:            101.422d
IMG_START_DATE:  18391 TJD;   273 DOY;   18/09/30
IMG_START_TIME:  46041.12 SOD {12:47:21.12} UT,   211.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     560004462
X_OFFSET:        815 [pixels]
Y_OFFSET:        848 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       975
Y_GRB_POS:       1008
BINNING_INDEX:   1
IM_URL:          sw00864584000msuni0233.fits
SUN_POSTN:       186.72d {+12h 26m 53s}   -2.90d {-02d 54' 10"}
SUN_DIST:        106.42 [deg]   Sun_angle= 7.3 [hr] (West of Sun)
MOON_POSTN:       72.39d {+04h 49m 33s}  +18.50d {+18d 30' 14"}
MOON_DIST:        43.85 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      226.55,-33.15 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       72.18,-47.77 [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:     Sun 30 Sep 18 12:51:24 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     864584,   Seg_Num: 0
GRB_RA:           76.8622d {+05h 07m 26.92s} (J2000),
                  77.0548d {+05h 08m 13.14s} (current),
                  76.3488d {+05h 05m 23.71s} (1950)
GRB_DEC:         -25.1166d {-25d 06' 59.7"} (J2000),
                 -25.0930d {-25d 05' 34.9"} (current),
                 -25.1811d {-25d 10' 51.9"} (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:  18391 TJD;   273 DOY;   18/09/30
IMG_START_TIME:  46090.00 SOD {12:48:10.00} UT,   260.7 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       186.72d {+12h 26m 52s}   -2.90d {-02d 54' 09"}
SUN_DIST:        106.43 [deg]   Sun_angle= 7.3 [hr] (West of Sun)
MOON_POSTN:       72.39d {+04h 49m 33s}  +18.50d {+18d 30' 12"}
MOON_DIST:        43.83 [deg]
MOON_ILLUM:      71 [%]
GAL_COORDS:      226.53,-33.15 [deg] galactic lon,lat of the burst
ECL_COORDS:       72.18,-47.75 [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 #23279
A. Tohuvavohu (PSU), S. D. Barthelmy (GSFC), D. N. Burrows (PSU), J.D. Gropp (PSU), J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL), D. M. Palmer (LANL) and B. Sbarufatti (PSU) report on behalf of the Neil Gehrels Swift Observatory Team:
At 12:43:49 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 180930A (trigger=864584). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 76.870, -25.138 which is
```
   RA(J2000) = 05h 07m 29s
   Dec(J2000) = -25d 08' 17"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 20 sec. The peak count rate was ~1000 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 12:47:17.6 UT, 208.3 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 76.86228, -25.11720 which is equivalent to:
```
   RA(J2000)  = 05h 07m 26.95s
   Dec(J2000) = -25d 07' 01.9"
```
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This location is 78 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.
A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (2.09 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 2.9 (+1.93/-1.74) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 211 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 none of the XRT error circle. 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 0.02.
Burst Advocate for this burst is A. Tohuvavohu (aaronb AT swift.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:     Sun 30 Sep 18 13:03:16 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     864584,   Seg_Num: 0
POINT_RA:         76.865d {+05h 07m 28s} (J2000)
POINT_DEC:       -25.139d {-25d 08' 20"} (J2000)
POINT_ROLL:      101.425d
IMG_START_DATE:  18391 TJD;   273 DOY;   18/09/30
IMG_START_TIME:  46689.72 SOD {12:58:09.72} UT,   860.5 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.690
N_STARS:         190
X_OFFSET:        256 [pixels]
Y_OFFSET:        289 [pixels]
X_MAX:           1695 [pixels]
Y_MAX:           1728 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw00864584000msufc0860.fits
SUN_POSTN:       186.73d {+12h 26m 54s}   -2.91d {-02d 54' 21"}
SUN_DIST:        106.43 [deg]   Sun_angle= 7.3 [hr] (West of Sun)
MOON_POSTN:       72.50d {+04h 50m 01s}  +18.52d {+18d 31' 24"}
MOON_DIST:        43.86 [deg]
MOON_ILLUM:      70 [%]
GAL_COORDS:      226.55,-33.15 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       72.18,-47.77 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 30 Sep 18 13:03:34 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     864584,   Seg_Num: 0
POINT_RA:         76.865d {+05h 07m 28s} (J2000)
POINT_DEC:       -25.139d {-25d 08' 20"} (J2000)
POINT_ROLL:      101.425d
IMG_START_DATE:  18391 TJD;   273 DOY;   18/09/30
IMG_START_TIME:  46689.72 SOD {12:58:09.72} UT,   860.5 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.690
N_STARS:         190
X_OFFSET:        256 [pixels]
Y_OFFSET:        289 [pixels]
X_MAX:           1695 [pixels]
Y_MAX:           1728 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw00864584000msufc0860.fits
SUN_POSTN:       186.73d {+12h 26m 54s}   -2.91d {-02d 54' 21"}
SUN_DIST:        106.43 [deg]   Sun_angle= 7.3 [hr] (West of Sun)
MOON_POSTN:       72.51d {+04h 50m 01s}  +18.52d {+18d 31' 26"}
MOON_DIST:        43.86 [deg]
MOON_ILLUM:      70 [%]
GAL_COORDS:      226.55,-33.15 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       72.18,-47.77 [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:     Sun 30 Sep 18 13:04:43 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     864584,   Seg_Num: 0
POINT_RA:         76.865d {+05h 07m 28s} (J2000)
POINT_DEC:       -25.139d {-25d 08' 20"} (J2000)
ROLL:            101.425d
IMG_START_DATE:  18391 TJD;   273 DOY;   18/09/30
IMG_START_TIME:  46689.72 SOD {12:58:09.72} UT,   860.5 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     560005111
X_OFFSET:        815 [pixels]
Y_OFFSET:        848 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       975
Y_GRB_POS:       1008
BINNING_INDEX:   1
IM_URL:          sw00864584000msuni0882.fits
SUN_POSTN:       186.73d {+12h 26m 54s}   -2.91d {-02d 54' 22"}
SUN_DIST:        106.43 [deg]   Sun_angle= 7.3 [hr] (West of Sun)
MOON_POSTN:       72.52d {+04h 50m 04s}  +18.53d {+18d 31' 33"}
MOON_DIST:        43.86 [deg]
MOON_ILLUM:      70 [%]
GAL_COORDS:      226.55,-33.15 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       72.18,-47.77 [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:     Sun 30 Sep 18 13:03:50 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     864584,   Seg_Num: 0
GRB_RA:           76.8635d {+05h 07m 27.24s} (J2000),
                  77.0561d {+05h 08m 13.45s} (current),
                  76.3501d {+05h 05m 24.03s} (1950)
GRB_DEC:         -25.1170d {-25d 07' 01.2"} (J2000),
                 -25.0935d {-25d 05' 36.4"} (current),
                 -25.1815d {-25d 10' 53.3"} (1950)
GRB_ERROR:       2.0 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  18391 TJD;   273 DOY;   18/09/30
IMG_START_TIME:  46090.00 SOD {12:48:10.00} UT,   260.7 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       186.73d {+12h 26m 54s}   -2.91d {-02d 54' 22"}
SUN_DIST:        106.44 [deg]   Sun_angle= 7.3 [hr] (West of Sun)
MOON_POSTN:       72.51d {+04h 50m 02s}  +18.52d {+18d 31' 27"}
MOON_DIST:        43.84 [deg]
MOON_ILLUM:      70 [%]
GAL_COORDS:      226.53,-33.14 [deg] galactic lon,lat of the burst
ECL_COORDS:       72.18,-47.75 [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 NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 30 Sep 18 13:04:56 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     864584,   Seg_Num: 0
POINT_RA:         76.865d {+05h 07m 28s} (J2000)
POINT_DEC:       -25.139d {-25d 08' 20"} (J2000)
ROLL:            101.425d
IMG_START_DATE:  18391 TJD;   273 DOY;   18/09/30
IMG_START_TIME:  46689.72 SOD {12:58:09.72} UT,   860.5 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     560005111
X_OFFSET:        815 [pixels]
Y_OFFSET:        848 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       975
Y_GRB_POS:       1008
BINNING_INDEX:   1
IM_URL:          sw00864584000msuni0882.fits
SUN_POSTN:       186.73d {+12h 26m 55s}   -2.91d {-02d 54' 23"}
SUN_DIST:        106.43 [deg]   Sun_angle= 7.3 [hr] (West of Sun)
MOON_POSTN:       72.52d {+04h 50m 05s}  +18.53d {+18d 31' 34"}
MOON_DIST:        43.86 [deg]
MOON_ILLUM:      70 [%]
GAL_COORDS:      226.55,-33.15 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       72.18,-47.77 [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 #23280
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Using promptly downlinked XRT event data for GRB 180930A, we find an enhanced XRT position of the afterglow: RA, Dec: 76.8633, -25.1169 which is equivalent to:
```
   RA (J2000)  = 05 07 27.19
   Dec (J2000) = -25 07 00.8
```
with an uncertainty of 2.0 arcseconds (radius, 90% confidence). Analysis of the promptly available data is online at http://www.swift.ac.uk/sper/864584.
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 #23281
WeiKang Zheng and Alexei V. Filippenko (UC Berkeley) report on behalf of the KAIT GRB team:
The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at Lick Observatory, responded to Swift GRB 180930A (Tohuvavohu et al., GCN 23279) starting at 12:45:41 UT, 112 seconds after the burst under dawn twilight condition. Observations were performed with an automatic sequence in the clear (roughly R), V, and I filters, and the exposure time was 20 s per image. We do not detect any optical afterglow candidate within the enhanced XRT position error circle (Evans et al., GCN 23280) neither in single image, nor in the co-add images. The typical limiting magnitude of our single clear image is about 18.5 mag calibrated to the Pan-STARRS1 catalog.
GCN Circular #23282
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team.
Using 2552 s of XRT Photon Counting mode data and 3 UVOT images for GRB 180930A, 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 = 76.86315, -25.11694 which is equivalent to:
```
RA (J2000): 05h 07m 27.16s
Dec (J2000): -25d 07' 01.0"
```
with an uncertainty of 1.7 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 #23283
N. P. M. Kuin (UCL-MSSL) and A. Tohuvavohu (PSU)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 180930A 212 s after the BAT trigger (Tohuvavohu et al., GCN Circ. 23279). No optical afterglow consistent with the XRT position (Evans GCN Circ. 23280) 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           212          362          147         >21.2
white              212         2818          602         >21.1
v                  517         2620          226         >20.1
b                  443         2718          240         >20.7
u                  418         2693          245         >19.7
w1                 394         2669          253         >20.8
m2                 369         2644          233         >19.3
w2                 659         2595          194         >19.9
```
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 #23284
Daniele B. Malesani (DAWN/NBI and DARK/NBI) and Ana Sagues (NOT) report on behalf of a larger collaboration:
We observed the field of GRB 180930A (Tohuvavohu et al., GCN 23279) with the Nordic Optical Telescope (NOT) equipped with the AlFOSC camera. Observations were carried out as soon as the field became visible from La Palma, starting on 2018 Oct 1.153 UT (14.95 hr after the GRB). A total exposure of 1500 s in each of the SDSS r and z filters was secured.
Inside the UVOT-enhanced GRB position (Osborne et al., GCN 23282), we detect no sources down to r = 23.5, z = 22.8 (both AB, calibrated against nearby stars from the Pan-STARRS survey).
GCN Circular #23285
D.N. Burrows (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), S. J. LaPorte (PSU) and A. Tohuvavohu report on behalf of the Swift-XRT team:
We have analysed 2.6 ks of XRT data for GRB 180930A (Tohuvavohu et al. GCN Circ. 23279), from 212 s to 6.0 ks after the BAT trigger. The data comprise 47 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN Circ. 23280).
The light curve can be modelled with a power-law decay with a decay index of alpha=2.04 (+/-0.09).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.01 (+/-0.15). The best-fitting absorption column is 7.2 (+3.7, -3.3) x 10^20 cm^-2, in excess of the Galactic value of 2.1 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 (3.9 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     7.2 (+3.7, -3.3) x 10^20 cm^-2
Galactic foreground: 2.1 x 10^20 cm^-2
Excess significance: 2.6 sigma
Photon index:	     2.01 (+/-0.15)
```
If the light curve continues to decay with a power-law decay index of 2.04, the count rate at T+24 hours will be 3.5 x 10^-5 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.2 x 10^-15 (1.4 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/00864584.
This circular is an official product of the Swift-XRT team.
GCN Circular #23286
S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), A. Tohuvavohu (PSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 180930A (trigger #864584) (Tohuvavohu, et al., GCN Circ. 23279). The BAT ground-calculated position is RA, Dec = 76.894, -25.124 deg which is
```
  RA(J2000)  =  05h 07m 34.6s 
  Dec(J2000) = -25d 07' 25.6" 
```
with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 87%.
The mask-weighted light curve shows a single episode of weak emission from T-4 sec to T+4 sec with several peaks. T90 (15-350 keV) is 6.80 +- 0.95 sec (estimated error including systematics).
The time-averaged spectrum from T-3.24 to T+4.20 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.86 +- 0.28. The fluence in the 15-150 keV band is 2.1 +- 0.4 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+0.14 sec in the 15-150 keV band is 0.9 +- 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/864584/BA/
GCN Circular #23302
E. Mazaeva (IKI), A. Kusakin (FAPHI), A. Pozanenko (IKI), I. Reva (FAPHI), A. Volnova (IKI), M. Krugov (FAPHI) report on behalf of larger GRB follow-up collaboration:
We observed the field of GRB 180930A (Tohuvavohu et al., GCN 23279) with Zeiss-1000 1-m telescope of Tien Shan Astronomical Observatory starting on September 30 (UT) 21:55:14, obtaining a total of 31*120 s exposure in the Rc-band. Within enhanced XRT position (Osborne et al., GCN 23282) we do not detect any object. Preliminary photometry of the field is following.
```
Date       UT start t-T0    Filter Exp.   OT    Err. UL
                     (mid, days) (s)

2018-09-30 21:55:14 0.41030 R      31*120 n/d   n/d 20.1
```
The photometry is based on several nearby USNO-B1.0 stars.

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Jochen Greiner, last update: 03-Oct-2018 [Disclaimer]