Gamma-ray Burst 180204A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

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Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 04 Feb 18 02:36:28 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     808483,   Seg_Num: 0
GRB_RA:          330.118d {+22h 00m 28s} (J2000),
                 330.320d {+22h 01m 17s} (current),
                 329.560d {+21h 58m 14s} (1950)
GRB_DEC:         +30.846d {+30d 50' 45"} (J2000),
                 +30.933d {+30d 55' 59"} (current),
                 +30.605d {+30d 36' 18"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       918 [cnts]    Image_Peak=85 [image_cnts]
TRIGGER_DUR:     0.064 [sec] 
TRIGGER_INDEX:   10427     E_range: 50-350 keV
BKG_INTEN:       16647 [cnts]
BKG_TIME:        9363.57 SOD {02:36:03.57} UT
BKG_DUR:         8 [sec]
GRB_DATE:        18153 TJD;    35 DOY;   18/02/04
GRB_TIME:        9376.69 SOD {02:36:16.69} UT
GRB_PHI:          -6.86 [deg]
GRB_THETA:        36.82 [deg]
SOLN_STATUS:     0x20000003
RATE_SIGNIF:     63.49 [sigma]
IMAGE_SIGNIF:    7.65 [sigma]
MERIT_PARAMS:     +1  +0  +0  -4  +3  -2  +0  +0 -66  +0 
SUN_POSTN:       317.69d {+21h 10m 45s}  -16.27d {-16d 16' 08"}
SUN_DIST:         48.74 [deg]   Sun_angle= -0.8 [hr] (East of Sun)
MOON_POSTN:      184.10d {+12h 16m 24s}   +2.46d {+02d 27' 32"}
MOON_DIST:       133.65 [deg]
MOON_ILLUM:      84 [%]
GAL_COORDS:       84.86,-19.11 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      345.79, 39.83 [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 = 206.54,18.94 [deg].  
COMMENTS:           
COMMENTS:        NOTE: This BAT event is temporally(0.0<100sec) coincident with the FERMI_GBM event (trignum=539404581).

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sun 04 Feb 18 02:36:41 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      46
TRIGGER_NUM:     539404581
GRB_RA:          202.600d {+13h 30m 24s} (J2000),
                 202.791d {+13h 31m 10s} (current),
                 202.071d {+13h 28m 17s} (1950)
GRB_DEC:         +46.500d {+46d 30' 00"} (J2000),
                 +46.407d {+46d 24' 25"} (current),
                 +46.758d {+46d 45' 27"} (1950)
GRB_ERROR:       4.10 [deg radius, statistical plus systematic]
GRB_INTEN:       1213 [cnts/sec]
DATA_SIGNIF:     33.20 [sigma]
INTEG_TIME:      0.256 [sec]
GRB_DATE:        18153 TJD;    35 DOY;   18/02/04
GRB_TIME:        9376.93 SOD {02:36:16.93} UT
GRB_PHI:         336.00 [deg]
GRB_THETA:       155.00 [deg]
DATA_TIME_SCALE: 0.2560 [sec]
HARD_RATIO:      0.00
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:     100%  Below horizon
2nd_MOST_LIKELY:   0%  n/a
DETECTORS:       0,1,0, 1,1,1, 0,1,0, 0,0,0, 0,0,
SUN_POSTN:       317.69d {+21h 10m 45s}  -16.27d {-16d 16' 08"}
SUN_DIST:        118.79 [deg]   Sun_angle= 7.7 [hr] (West of Sun)
MOON_POSTN:      184.10d {+12h 16m 24s}   +2.46d {+02d 27' 29"}
MOON_DIST:        46.87 [deg]
MOON_ILLUM:      84 [%]
GAL_COORDS:      103.83, 69.16 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      175.87, 50.42 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2018/bn180204109/quicklook/glg_lc_medres34_bn180204109.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 201.32,13.50 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(0.0<100sec) coincident with the SWIFT_BAT event (trignum=808483).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 04 Feb 18 02:37:50 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     808483,   Seg_Num: 0
POINT_RA:        330.103d {+22h 00m 25s} (J2000)
POINT_DEC:       +30.820d {+30d 49' 13"} (J2000)
IMG_START_DATE:  18153 TJD;    35 DOY;   18/02/04
IMG_START_TIME:  9463.86 SOD {02:37:43.86} UT,   87.2 [sec] since BAT Trigger Time
COUNTS:          9    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 04 Feb 18 02:40:26 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     808483,   Seg_Num: 0
GRB_RA:          330.118d {+22h 00m 28s} (J2000),
                 330.320d {+22h 01m 17s} (current),
                 329.560d {+21h 58m 14s} (1950)
GRB_DEC:         +30.846d {+30d 50' 45"} (J2000),
                 +30.933d {+30d 55' 59"} (current),
                 +30.605d {+30d 36' 18"} (1950)
GRB_DATE:        18153 TJD;    35 DOY;   18/02/04
GRB_TIME:        9376.94 SOD {02:36:16.94} UT
TRIGGER_INDEX:   10427
GRB_PHI:          -6.86 [deg]
GRB_THETA:        36.82 [deg]
DELTA_TIME:      -56.00 [sec]
TRIGGER_DUR:     0.064 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     63.49 [sigma]
IMAGE_SIGNIF:    7.65 [sigma]
LC_URL:          sw00808483000msb.lc
SUN_POSTN:       317.69d {+21h 10m 45s}  -16.27d {-16d 16' 05"}
SUN_DIST:         48.74 [deg]   Sun_angle= -0.8 [hr] (East of Sun)
MOON_POSTN:      184.13d {+12h 16m 32s}   +2.45d {+02d 26' 46"}
MOON_DIST:       133.64 [deg]
MOON_ILLUM:      84 [%]
GAL_COORDS:       84.86,-19.11 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      345.79, 39.83 [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 = 206.54,18.94 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 04 Feb 18 02:42:45 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     808483,   Seg_Num: 0
GRB_RA:          330.1335d {+22h 00m 32.04s} (J2000),
                 330.3354d {+22h 01m 20.50s} (current),
                 329.5761d {+21h 58m 18.25s} (1950)
GRB_DEC:         +30.8380d {+30d 50' 16.8"} (J2000),
                 +30.9254d {+30d 55' 31.5"} (current),
                 +30.5972d {+30d 35' 50.0"} (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:  18153 TJD;    35 DOY;   18/02/04
IMG_START_TIME:  9517.00 SOD {02:38:37.00} UT,   140.3 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       317.69d {+21h 10m 46s}  -16.27d {-16d 16' 03"}
SUN_DIST:         48.73 [deg]   Sun_angle= -0.8 [hr] (East of Sun)
MOON_POSTN:      184.15d {+12h 16m 37s}   +2.44d {+02d 26' 19"}
MOON_DIST:       133.64 [deg]
MOON_ILLUM:      84 [%]
GAL_COORDS:       84.86,-19.12 [deg] galactic lon,lat of the burst
ECL_COORDS:      345.80, 39.82 [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:     Sun 04 Feb 18 02:53:44 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     808483,   Seg_Num: 0
POINT_RA:        330.104d {+22h 00m 25s} (J2000)
POINT_DEC:       +30.820d {+30d 49' 12"} (J2000)
POINT_ROLL:      195.990d
IMG_START_DATE:  18153 TJD;    35 DOY;   18/02/04
IMG_START_TIME:  9468.79 SOD {02:37:48.79} UT,   92.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.197
N_STARS:         95
X_OFFSET:        286 [pixels]
Y_OFFSET:        637 [pixels]
X_MAX:           1245 [pixels]
Y_MAX:           1596 [pixels]
DET_THRESH:      17
PHOTO_THRESH:    10
SL_URL:          sw00808483000msufc0092.fits
SUN_POSTN:       317.70d {+21h 10m 47s}  -16.27d {-16d 15' 55"}
SUN_DIST:         48.71 [deg]   Sun_angle= -0.8 [hr] (East of Sun)
MOON_POSTN:      184.25d {+12h 17m 01s}   +2.40d {+02d 24' 11"}
MOON_DIST:       133.60 [deg]
MOON_ILLUM:      84 [%]
GAL_COORDS:       84.83,-19.12 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      345.76, 39.82 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 04 Feb 18 02:53:57 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     808483,   Seg_Num: 0
POINT_RA:        330.104d {+22h 00m 25s} (J2000)
POINT_DEC:       +30.820d {+30d 49' 12"} (J2000)
POINT_ROLL:      195.990d
IMG_START_DATE:  18153 TJD;    35 DOY;   18/02/04
IMG_START_TIME:  9468.79 SOD {02:37:48.79} UT,   92.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.197
N_STARS:         95
X_OFFSET:        286 [pixels]
Y_OFFSET:        637 [pixels]
X_MAX:           1245 [pixels]
Y_MAX:           1596 [pixels]
DET_THRESH:      17
PHOTO_THRESH:    10
SL_URL:          sw00808483000msufc0092.fits
SUN_POSTN:       317.70d {+21h 10m 47s}  -16.27d {-16d 15' 55"}
SUN_DIST:         48.71 [deg]   Sun_angle= -0.8 [hr] (East of Sun)
MOON_POSTN:      184.26d {+12h 17m 01s}   +2.40d {+02d 24' 09"}
MOON_DIST:       133.60 [deg]
MOON_ILLUM:      84 [%]
GAL_COORDS:       84.83,-19.12 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      345.76, 39.82 [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 04 Feb 18 02:55:26 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     808483,   Seg_Num: 0
POINT_RA:        330.104d {+22h 00m 25s} (J2000)
POINT_DEC:       +30.820d {+30d 49' 12"} (J2000)
ROLL:            195.990d
IMG_START_DATE:  18153 TJD;    35 DOY;   18/02/04
IMG_START_TIME:  9468.79 SOD {02:37:48.79} UT,   92.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     539404689
X_OFFSET:        605 [pixels]
Y_OFFSET:        956 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       765
Y_GRB_POS:       1116
BINNING_INDEX:   1
IM_URL:          sw00808483000msuni0113.fits
SUN_POSTN:       317.70d {+21h 10m 48s}  -16.27d {-16d 15' 54"}
SUN_DIST:         48.71 [deg]   Sun_angle= -0.8 [hr] (East of Sun)
MOON_POSTN:      184.27d {+12h 17m 04s}   +2.40d {+02d 23' 51"}
MOON_DIST:       133.59 [deg]
MOON_ILLUM:      84 [%]
GAL_COORDS:       84.83,-19.12 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      345.76, 39.82 [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 04 Feb 18 02:55:35 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     808483,   Seg_Num: 0
POINT_RA:        330.104d {+22h 00m 25s} (J2000)
POINT_DEC:       +30.820d {+30d 49' 12"} (J2000)
ROLL:            195.990d
IMG_START_DATE:  18153 TJD;    35 DOY;   18/02/04
IMG_START_TIME:  9468.79 SOD {02:37:48.79} UT,   92.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     539404689
X_OFFSET:        605 [pixels]
Y_OFFSET:        956 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       765
Y_GRB_POS:       1116
BINNING_INDEX:   1
IM_URL:          sw00808483000msuni0113.fits
SUN_POSTN:       317.70d {+21h 10m 48s}  -16.27d {-16d 15' 53"}
SUN_DIST:         48.71 [deg]   Sun_angle= -0.8 [hr] (East of Sun)
MOON_POSTN:      184.27d {+12h 17m 05s}   +2.40d {+02d 23' 50"}
MOON_DIST:       133.59 [deg]
MOON_ILLUM:      84 [%]
GAL_COORDS:       84.83,-19.12 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      345.76, 39.82 [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 #22375
K. L. Page (U Leicester), A. P. Beardmore (U Leicester), A. Deich (PSU), J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL), A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), A. Tohuvavohu (PSU) and T. N. Ukwatta (LANL) report on behalf of the Neil Gehrels Swift Observatory Team:
At 02:36:16 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 180204A (trigger=808483). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 330.118, +30.846 which is
```
   RA(J2000) = 22h 00m 28s
   Dec(J2000) = +30d 50' 45"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a double-peaked structure with a duration of about 1.5 sec. The peak count rate was ~17000 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 02:37:43.8 UT, 87.2 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 330.13359, 30.83807 which is equivalent to:
```
   RA(J2000)  = 22h 00m 32.06s
   Dec(J2000) = +30d 50' 17.1"
```
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This location is 56 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 92 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 0.10.
Burst Advocate for this burst is K. L. Page (klp5 AT leicester.ac.uk). 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 04 Feb 18 03:00:44 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     808483,   Seg_Num: 0
POINT_RA:        330.106d {+22h 00m 25s} (J2000)
POINT_DEC:       +30.819d {+30d 49' 08"} (J2000)
POINT_ROLL:      195.991d
IMG_START_DATE:  18153 TJD;    35 DOY;   18/02/04
IMG_START_TIME:  9680.87 SOD {02:41:20.87} UT,   304.2 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.156
N_STARS:         190
X_OFFSET:        46 [pixels]
Y_OFFSET:        397 [pixels]
X_MAX:           1485 [pixels]
Y_MAX:           1836 [pixels]
DET_THRESH:      9
PHOTO_THRESH:    4
SL_URL:          sw00808483000msufc0304.fits
SUN_POSTN:       317.70d {+21h 10m 49s}  -16.26d {-16d 15' 50"}
SUN_DIST:         48.70 [deg]   Sun_angle= -0.8 [hr] (East of Sun)
MOON_POSTN:      184.32d {+12h 17m 16s}   +2.38d {+02d 22' 50"}
MOON_DIST:       133.58 [deg]
MOON_ILLUM:      84 [%]
GAL_COORDS:       84.83,-19.12 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      345.76, 39.81 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sun 04 Feb 18 03:00:57 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     808483,   Seg_Num: 0
POINT_RA:        330.106d {+22h 00m 25s} (J2000)
POINT_DEC:       +30.819d {+30d 49' 08"} (J2000)
POINT_ROLL:      195.991d
IMG_START_DATE:  18153 TJD;    35 DOY;   18/02/04
IMG_START_TIME:  9680.87 SOD {02:41:20.87} UT,   304.2 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.156
N_STARS:         190
X_OFFSET:        46 [pixels]
Y_OFFSET:        397 [pixels]
X_MAX:           1485 [pixels]
Y_MAX:           1836 [pixels]
DET_THRESH:      9
PHOTO_THRESH:    4
SL_URL:          sw00808483000msufc0304.fits
SUN_POSTN:       317.70d {+21h 10m 49s}  -16.26d {-16d 15' 49"}
SUN_DIST:         48.70 [deg]   Sun_angle= -0.8 [hr] (East of Sun)
MOON_POSTN:      184.32d {+12h 17m 16s}   +2.38d {+02d 22' 47"}
MOON_DIST:       133.57 [deg]
MOON_ILLUM:      84 [%]
GAL_COORDS:       84.83,-19.12 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      345.76, 39.81 [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 04 Feb 18 03:01:28 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     808483,   Seg_Num: 0
GRB_RA:          330.1336d {+22h 00m 32.06s} (J2000),
                 330.3355d {+22h 01m 20.52s} (current),
                 329.5762d {+21h 58m 18.27s} (1950)
GRB_DEC:         +30.8381d {+30d 50' 17.1"} (J2000),
                 +30.9255d {+30d 55' 31.9"} (current),
                 +30.5973d {+30d 35' 50.4"} (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:  18153 TJD;    35 DOY;   18/02/04
IMG_START_TIME:  9517.00 SOD {02:38:37.00} UT,   140.3 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       317.70d {+21h 10m 49s}  -16.26d {-16d 15' 49"}
SUN_DIST:         48.73 [deg]   Sun_angle= -0.8 [hr] (East of Sun)
MOON_POSTN:      184.32d {+12h 17m 17s}   +2.38d {+02d 22' 41"}
MOON_DIST:       133.58 [deg]
MOON_ILLUM:      84 [%]
GAL_COORDS:       84.86,-19.12 [deg] galactic lon,lat of the burst
ECL_COORDS:      345.80, 39.82 [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 #22376
J.P. Osborne (U. Leicester), A.P. Beardmore (U. Leicester), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), D.N. Burrows (PSU), A. Tohuvavohu (PSU), S. J. LaPorte (PSU) and K.L. Page report on behalf of the Swift-XRT team:
We have analysed 8.0 ks of XRT data for GRB 180204A (Page et al. GCN Circ. 22375), from 90 s to 21.2 ks after the BAT trigger. The data comprise 32 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The best available XRT position (using the promptly downlinked event data, the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue) is RA, Dec = 330.1333, 30.8381 which is equivalent to:
```
RA (J2000): 22 00 32.00
Dec(J2000): +30 50 17.1
```
with an uncertainty of 2.1 arcsec (radius, 90% confidence).
The light curve can be modelled with a power-law decay with a decay index of alpha=1.15 (+/-0.03).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.02 (+0.23, -0.22). The best-fitting absorption column is 6.9 (+1.7, -1.5) x 10^21 cm^-2, in excess of the Galactic value of 1.0 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.3 x 10^-11 (7.6 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     6.9 (+1.7, -1.5) x 10^21 cm^-2
Galactic foreground: 1.0 x 10^21 cm^-2
Excess significance: 6.5 sigma
Photon index:	     2.02 (+0.23, -0.22)
```
If the light curve continues to decay with a power-law decay index of 1.15, the count rate at T+24 hours will be 2.7 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.2 x 10^-13 (2.0 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/00808483.
This circular is an official product of the Swift-XRT team.
GCN Circular #22377
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team.
Using 6274 s of XRT Photon Counting mode data and 9 UVOT images for GRB 180204A, 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 = 330.13329, +30.83785 which is equivalent to:
```
RA (J2000): 22h 00m 31.99s
Dec (J2000): +30d 50' 16.2"
```
with an uncertainty of 1.4 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177).
This circular was automatically generated, and is an official product of the Swift-XRT team.
GCN Circular #22378
P. Veres and C. Meegan (both UAH) report on behalf of the Fermi GBM Team:
"At 02:36:16.93 UT on 04 February 2018, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 180204A (trigger 539404581 / 180204109) which was also detected by the Swift/BAT (Page et al., GCN 22375). The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 68 degrees.
The GBM light curve shows two peaks with a duration (T90) of about 1.2 s (50-300 keV). The time-averaged spectrum from T0-0.1 s to T0+1.2 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.92 +/- 0.07 and the cutoff energy, parameterized as Epeak, is 781 +/- 161 keV.
The event fluence (10-1000 keV) in this time interval is (8.48 +/- 0.32)E-7 erg/cm^2. The 64-msec peak photon flux measured starting from T0 in the 10-1000 keV band is 19.7 +/- 1.6 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN Circular #22379
N. P. M. Kuin (UCL-MSSL) and K. L. Page (U. Leicester) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 180204A 92 s after the BAT trigger (Page et al., GCN Circ. 22375). A star is present in the GSC whos position is consistent with the enhanced XRT position (Osborne et al. GCN Circ. 22377). No optical afterglow above the stellar flux has been 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            92          242          147         >20.3
u_FC               304          554          246         >19.9
white               92        17884         1210         >20.8
v                  633        10587         1107         >19.0
b                  560        23622         1840         >20.7
u                  304        23062         2409         >21.1
w1                3943        22148         1917         >21.0
m2                 658        11492         1095         >20.8
w2                 609         6398          413         >20.1
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.10 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #22380
J. R. Cummings (CPI), S. D. Barthelmy (GSFC), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), J. P. Norris (BSU), K. L. Page (U Leicester), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-186 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 180204A (trigger #808483) (Page et al., GCN Circ. 22375). The BAT ground-calculated position is RA, Dec = 330.123, 30.852 deg which is
```
  RA(J2000)  =  22h 00m 29.5s
  Dec(J2000) = +30d 51' 07.5"
```
with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 70%.
The mask-weighted light curve shows two distict pulses. The first pulse starts and peaks at ~T0, and ends at ~T+0.2. The second pulse starts at ~T+0.6 s, peaks at ~T+1 s, and ends at ~T+1.3 s. T90 (15-350 keV) is 1.16 +- 0.12 sec (estimated error including systematics).
For the first pulse, the lag analysis finds a lag of -0.2 +- 1 ms for the 100-350 keV to 25-100 keV, and 0.2 +- 1.5 ms for the 50-100 keV to 15-25 keV band. The second pulse has a lag of 5.6 +- 3.9 ms for the 100-350 keV to 25-100 keV, and 3.2 +- 6.6 ms for the 50-100 keV to 15-25 keV band. These values are consistent with those of a short GRB.
The time-averaged spectrum from T-0.05 to T+1.29 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.09 +- 0.10. The fluence in the 15-150 keV band is 4.8 +- 0.3 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T-0.05 sec in the 15-150 keV band is 3.6 +- 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/808483/BA/
GCN Circular #22385
A. Kozlova, S. Golenetskii, R. Aptekar, D. Frederiks, P. Oleynik, M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline on behalf of the Konus-Wind team, report:
The short-duration GRB 180204A (Swift-BAT detection and analysis: Page et al., GCN 22375; Cummings et al., GCN 22380; Fermi-GBM observation: Veres&Meegan, GCN 22378) triggered Konus-Wind at T0=9372.902 s UT (02:36:12.902).
The burst light curve shows two peaks in the interval from ~T0-0.1 s to ~T0+1.1 s. The emission is seen up to ~10 MeV.
As observed by Konus-Wind, the burst had a fluence of 3.81(-0.57,+0.66)x10^-6 erg/cm2, and a 16-ms peak flux, measured from T0+0.038 s, of 2.95(-0.80,+0.87)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
The spectrum of the burst (measured from T0 to T0+0.256 s) is best fit in the 20 keV - 10 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.36(-0.29,+0.38) and Ep = 843(-177,+263) keV (chi2 = 37/45 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.5 (chi2 = 37/44 dof)
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB180204_T09372/
All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.
GCN Circular #22399
K. Morita, R. Itoh, K. L. Murata, T. Yoshii, Y. Tachibana, S. Harita, T. Ozawa, H. Mamiya, K. Shiraishi, Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration:
We searched for the optical counterpart of GRB 180204A (K. L. Page et al., GCN Circular #22375) with the optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope of Okayama Astrophysical Observatory, Japan. The observation started on 2018-02-04 9:37:11.83 UT. We did not find any new point source within the XRT circle (J. P. Osborne et al., GCN Circular #22377) in all three bands. We obtained following limits for the magnitudes.
```
T0+[h]    MID-UT      T-EXP[sec]    g'        Rc        Ic
------------------------------------------------------------
-------------------------------------------
~7.0         9:48:54         1140       >17.5     >17.4      >17.0
------------------------------------------------------------
-------------------------------------------
```
T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used GSC2.3 catalog for flux calibration
GCN Circular #22422
J. Bright, R. Fender (Oxford), and K. P. Mooley (NRAO, Caltech; Jansky Fellow)
We have initiated the AMI short-GRB program. We observed the field of GRB 180204A (Page et al., GCN 22375) with the AMI Large Array at 15.5 GHz. Our observations on 2018 Feb 04.54, Feb 05.55, Feb 06.62 and Feb 09-11 (0.43 d, 1.44 d, 2.51 d and 5-7 d coadd post-burst) do not reveal any radio source at the XRT location (Osborne et al., GCN 22377), with 3sigma upper limits of 55 uJy, 54 uJy, 76 uJy and 63 uJy respectively.
Results from the AMI short-GRB program will be posted on the AMI-GRB database available at http://4pisky.org/ami-grb/ . We thank the MRAO staff for scheduling these observations.

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Jochen Greiner, last update: 19-Feb-2018 [Disclaimer]