Gamma-ray Burst 190204A

(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:     Mon 04 Feb 19 05:46:16 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     887579,   Seg_Num: 0
GRB_RA:          351.534d {+23h 26m 08s} (J2000),
                 351.756d {+23h 27m 02s} (current),
                 350.953d {+23h 23m 49s} (1950)
GRB_DEC:         +54.883d {+54d 52' 58"} (J2000),
                 +54.988d {+54d 59' 16"} (current),
                 +54.608d {+54d 36' 27"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       4031 [cnts]    Image_Peak=319 [image_cnts]
TRIGGER_DUR:     1.024 [sec] 
TRIGGER_INDEX:   146     E_range: 25-100 keV
BKG_INTEN:       17901 [cnts]
BKG_TIME:        20745.63 SOD {05:45:45.63} UT
BKG_DUR:         8 [sec]
GRB_DATE:        18518 TJD;    35 DOY;   19/02/04
GRB_TIME:        20760.74 SOD {05:46:00.74} UT
GRB_PHI:         145.87 [deg]
GRB_THETA:        31.30 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     34.04 [sigma]
IMAGE_SIGNIF:    13.71 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +2  +3  +0  +1 -22  +0 
SUN_POSTN:       317.57d {+21h 10m 18s}  -16.30d {-16d 18' 06"}
SUN_DIST:         76.96 [deg]   Sun_angle= -2.3 [hr] (East of Sun)
MOON_POSTN:      310.86d {+20h 43m 27s}  -19.25d {-19d 15' 16"}
MOON_DIST:        81.99 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      110.79, -5.97 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       23.52, 51.64 [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 = 119.45,18.13 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 04 Feb 19 05:46:46 UT
NOTICE_TYPE:     Swift-BAT GRB Position 
TRIGGER_NUM:     887580,   Seg_Num: 0   
GRB_RA:          351.514d {+23h 26m 03s} (J2000),
                 351.737d {+23h 26m 57s} (current),
                 350.934d {+23h 23m 44s} (1950)
GRB_DEC:         +54.878d {+54d 52' 42"} (J2000),
                 +54.984d {+54d 59' 01"} (current),
                 +54.603d {+54d 36' 12"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       5197 [cnts]    Image_Peak=826 [image_cnts]
TRIGGER_DUR:     0.256 [sec]    
TRIGGER_INDEX:   123     E_range: 25-100 keV
BKG_INTEN:       25914 [cnts]
BKG_TIME:        20753.63 SOD {05:45:53.63} UT
BKG_DUR:         8 [sec] 
GRB_DATE:        18518 TJD;    35 DOY;   19/02/04
GRB_TIME:        20766.05 SOD {05:46:06.05} UT
GRB_PHI:         145.88 [deg]
GRB_THETA:        31.28 [deg]
SOLN_STATUS:     0x3000000D  
RATE_SIGNIF:     148.71 [sigma]
IMAGE_SIGNIF:    20.24 [sigma]
MERIT_PARAMS:     +0  +0 +100  -2  +2  +7  +0  +1 -22  +0
SUN_POSTN:       317.57d {+21h 10m 18s}  -16.30d {-16d 18' 06"}
SUN_DIST:         76.95 [deg]   Sun_angle= -2.3 [hr] (East of Sun)
MOON_POSTN:      310.87d {+20h 43m 28s}  -19.25d {-19d 15' 14"}
MOON_DIST:        81.98 [deg] 
MOON_ILLUM:      0 [%]
GAL_COORDS:      110.78, -5.97 [deg] galactic lon,lat of the burst (or transient)      
ECL_COORDS:       23.50, 51.65 [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 matches a source in the on-board catalog: Num=27579=(null) (probably an AT_Slot).
COMMENTS:        This does not match any source in the ground catalog.
COMMENTS:        This is not a GRB. 
COMMENTS:        This is an interesting source.
COMMENTS:        This trigger occurred at longitude,latitude = 119.45,18.13 [deg].
COMMENTS:
COMMENTS:        NOTE: This BAT event is spatially(0.00<0.1deg) and temporally(6.0<100sec) coincident with the SWIFT_BAT event (trignum=887579).

GCN NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Mon 04 Feb 19 05:46:48 UT
NOTICE_TYPE:    INTEGRAL SPI ACS Trigger
TRIGGER_NUM:    8219,   Sub_Num: 0
GRB_INTEN:      10.14 [sigma]  
GRB_TIME:       20764.37 SOD {05:46:04.37} UT
GRB_DATE:       18518 TJD;    35 DOY;   19/02/04
COMMENTS:       INTEGRAL SPI_ACS GRB Trigger.
COMMENTS:       Time_Scale=0.2000 and Time_Error=0.1000.
COMMENTS:
COMMENTS:       NOTE: This SPIACS event is temporally(2.0<100sec) coincident with the SWIFT_BAT event (trignum=887580).
COMMENTS:
COMMENTS:       The SPIACS lightcurve can be found at:
COMMENTS:       ftp://isdcarc.unige.ch/arc/FTP/ibas/spiacs/2019-02/2019-02-04T05-46-04.2607-17151-60304-0.lc

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 04 Feb 19 05:47:45 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     887579,   Seg_Num: 0
GRB_RA:          351.4770d {+23h 25m 54.47s} (J2000),
                 351.6995d {+23h 26m 47.87s} (current),
                 350.8968d {+23h 23m 35.23s} (1950)
GRB_DEC:         +54.8775d {+54d 52' 38.9"} (J2000),
                 +54.9827d {+54d 58' 57.5"} (current),
                 +54.6024d {+54d 36' 08.5"} (1950)
GRB_ERROR:       4.8 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       5.72e-09 [erg/cm2/sec]
GRB_SIGNIF:      12.76 [sigma]
IMG_START_DATE:  18518 TJD;    35 DOY;   19/02/04
IMG_START_TIME:  20835.73 SOD {05:47:15.73} UT,   69.7 [sec] since BAT Trigger Time
TAM[0-3]:        327.68 237.22 261.71 243.45
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       317.57d {+21h 10m 18s}  -16.30d {-16d 18' 05"}
SUN_DIST:         76.94 [deg]   Sun_angle= -2.3 [hr] (East of Sun)
MOON_POSTN:      310.88d {+20h 43m 30s}  -19.25d {-19d 15' 09"}
MOON_DIST:        81.96 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      110.76, -5.96 [deg] galactic lon,lat of the burst
ECL_COORDS:       23.48, 51.66 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:           
COMMENTS:        WARNING: No BAT_Position TDRSS message was received for this trigger_number!  
COMMENTS:           
COMMENTS:        The XRT position is 1.28 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:     Mon 04 Feb 19 05:47:56 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     887579,   Seg_Num: 0
GRB_RA:          351.4770d {+23h 25m 54.4s} (J2000),
                 351.6995d {+23h 26m 47.8s} (current),
                 350.8968d {+23h 23m 35.2s} (1950)
GRB_DEC:         +54.8775d {+54d 52' 38.9"} (J2000),
                 +54.9827d {+54d 58' 57.5"} (current),
                 +54.6024d {+54d 36' 08.5"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       163 [cnts]
IMG_START_DATE:  18518 TJD;    35 DOY;   19/02/04
IMG_START_TIME:  20835.73 SOD {05:47:15.73} UT,   69.7 [sec] since BAT Trigger Time
CENTROID_X:      288.97,  raw= 289  [pixels]
CENTROID_Y:      263.55,  raw= 264  [pixels]
ROLL:            213.43 [deg]
GAIN:            2
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -82.14
GRB_POS_XRT_Z:   -41.07
IMAGE_URL:       sw00887579000msxps_rw.img
SUN_POSTN:       317.57d {+21h 10m 18s}  -16.30d {-16d 18' 05"}
SUN_DIST:         76.94 [deg]   Sun_angle= -2.3 [hr] (East of Sun)
MOON_POSTN:      310.88d {+20h 43m 31s}  -19.25d {-19d 15' 08"}
MOON_DIST:        81.96 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      110.76, -5.96 [deg] galactic lon,lat of the burst
ECL_COORDS:       23.48, 51.66 [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:     Mon 04 Feb 19 05:47:58 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     887579,   Seg_Num: 0
GRB_RA:          351.4770d {+23h 25m 54.4s} (J2000),
                 351.6995d {+23h 26m 47.8s} (current),
                 350.8968d {+23h 23m 35.2s} (1950)
GRB_DEC:         +54.8775d {+54d 52' 38.9"} (J2000),
                 +54.9827d {+54d 58' 57.5"} (current),
                 +54.6024d {+54d 36' 08.5"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       163 [cnts]
IMG_START_DATE:  18518 TJD;    35 DOY;   19/02/04
IMG_START_TIME:  20835.73 SOD {05:47:15.73} UT,   69.7 [sec] since BAT Trigger Time
CENTROID_X:      288.97,  raw= 289  [pixels]
CENTROID_Y:      263.55,  raw= 264  [pixels]
ROLL:            213.43 [deg]
GAIN:            2
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -82.14
GRB_POS_XRT_Z:   -41.07
IMAGE_URL:       sw00887579000msxps_rw.img
SUN_POSTN:       317.57d {+21h 10m 18s}  -16.30d {-16d 18' 05"}
SUN_DIST:         76.94 [deg]   Sun_angle= -2.3 [hr] (East of Sun)
MOON_POSTN:      310.88d {+20h 43m 31s}  -19.25d {-19d 15' 08"}
MOON_DIST:        81.96 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      110.76, -5.96 [deg] galactic lon,lat of the burst
ECL_COORDS:       23.48, 51.66 [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:     Mon 04 Feb 19 05:50:19 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     887579,   Seg_Num: 0
POINT_RA:        351.522d {+23h 26m 05s} (J2000)
POINT_DEC:       +54.874d {+54d 52' 26"} (J2000)
POINT_ROLL:      213.428d
IMG_START_DATE:  18518 TJD;    35 DOY;   19/02/04
IMG_START_TIME:  20844.26 SOD {05:47:24.26} UT,   78.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.342
N_STARS:         190
X_OFFSET:        392 [pixels]
Y_OFFSET:        584 [pixels]
X_MAX:           1351 [pixels]
Y_MAX:           1543 [pixels]
DET_THRESH:      15
PHOTO_THRESH:    8
SL_URL:          sw00887579000msufc0078.fits
SUN_POSTN:       317.58d {+21h 10m 18s}  -16.30d {-16d 18' 03"}
SUN_DIST:         76.95 [deg]   Sun_angle= -2.3 [hr] (East of Sun)
MOON_POSTN:      310.90d {+20h 43m 36s}  -19.25d {-19d 14' 55"}
MOON_DIST:        81.96 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      110.78, -5.97 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       23.51, 51.64 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 04 Feb 19 05:50:40 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     887579,   Seg_Num: 0
POINT_RA:        351.522d {+23h 26m 05s} (J2000)
POINT_DEC:       +54.874d {+54d 52' 26"} (J2000)
POINT_ROLL:      213.428d
IMG_START_DATE:  18518 TJD;    35 DOY;   19/02/04
IMG_START_TIME:  20844.26 SOD {05:47:24.26} UT,   78.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.342
N_STARS:         190
X_OFFSET:        392 [pixels]
Y_OFFSET:        584 [pixels]
X_MAX:           1351 [pixels]
Y_MAX:           1543 [pixels]
DET_THRESH:      15
PHOTO_THRESH:    8
SL_URL:          sw00887579000msufc0078.fits
SUN_POSTN:       317.58d {+21h 10m 18s}  -16.30d {-16d 18' 03"}
SUN_DIST:         76.95 [deg]   Sun_angle= -2.3 [hr] (East of Sun)
MOON_POSTN:      310.90d {+20h 43m 36s}  -19.25d {-19d 14' 54"}
MOON_DIST:        81.96 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      110.78, -5.97 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       23.51, 51.64 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 04 Feb 19 05:52:03 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     887579,   Seg_Num: 0
POINT_RA:        351.522d {+23h 26m 05s} (J2000)
POINT_DEC:       +54.874d {+54d 52' 26"} (J2000)
ROLL:            213.428d
IMG_START_DATE:  18518 TJD;    35 DOY;   19/02/04
IMG_START_TIME:  20844.26 SOD {05:47:24.26} UT,   78.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     570952066
X_OFFSET:        933 [pixels]
Y_OFFSET:        976 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1093
Y_GRB_POS:       1136
BINNING_INDEX:   1
IM_URL:          sw00887579000msuni0101.fits
SUN_POSTN:       317.58d {+21h 10m 19s}  -16.30d {-16d 18' 02"}
SUN_DIST:         76.95 [deg]   Sun_angle= -2.3 [hr] (East of Sun)
MOON_POSTN:      310.91d {+20h 43m 39s}  -19.25d {-19d 14' 47"}
MOON_DIST:        81.95 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      110.78, -5.97 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       23.51, 51.64 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 04 Feb 19 05:52:14 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     887579,   Seg_Num: 0
POINT_RA:        351.522d {+23h 26m 05s} (J2000)
POINT_DEC:       +54.874d {+54d 52' 26"} (J2000)
ROLL:            213.428d
IMG_START_DATE:  18518 TJD;    35 DOY;   19/02/04
IMG_START_TIME:  20844.26 SOD {05:47:24.26} UT,   78.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     570952066
X_OFFSET:        933 [pixels]
Y_OFFSET:        976 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1093
Y_GRB_POS:       1136
BINNING_INDEX:   1
IM_URL:          sw00887579000msuni0101.fits
SUN_POSTN:       317.58d {+21h 10m 19s}  -16.30d {-16d 18' 02"}
SUN_DIST:         76.95 [deg]   Sun_angle= -2.3 [hr] (East of Sun)
MOON_POSTN:      310.92d {+20h 43m 40s}  -19.25d {-19d 14' 46"}
MOON_DIST:        81.95 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      110.78, -5.97 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       23.51, 51.64 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 04 Feb 19 05:54:03 UT
NOTICE_TYPE:     Swift-UVOT Position
TRIGGER_NUM:     887579,   Seg_Num: 0
GRB_RA:          351.4770d {+23h 25m 54.47s} (J2000),
                 351.6995d {+23h 26m 47.87s} (current),
                 350.8968d {+23h 23m 35.23s} (1950)
GRB_DEC:         +54.8764d {+54d 52' 35.0"} (J2000),
                 +54.9816d {+54d 58' 53.5"} (current),
                 +54.6013d {+54d 36' 04.6"} (1950)
GRB_ERROR:       1.1 [arcsec radius, statistical only]
GRB_MAG:         17.70 +/- 0.40 [mag]
FILTER:          10, White
IMG_START_DATE:  18518 TJD;    35 DOY;   19/02/04
IMG_START_TIME:  20841.00 SOD {05:47:21.00} UT,   75.0 [sec] since BAT Trigger Time
SUN_POSTN:       317.58d {+21h 10m 19s}  -16.30d {-16d 18' 00"}
SUN_DIST:         76.93 [deg]   Sun_angle= -2.3 [hr] (East of Sun)
MOON_POSTN:      310.93d {+20h 43m 43s}  -19.24d {-19d 14' 36"}
MOON_DIST:        81.93 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      110.76, -5.96 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       23.48, 51.66 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT UVOT Position Notice.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The UVOT position is 4.0 arcsec from the XRT position.  
COMMENTS:        Result based on srclist data.  
COMMENTS:        Notice generated automatically.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 04 Feb 19 05:57:33 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     887579,   Seg_Num: 0
POINT_RA:        351.517d {+23h 26m 04s} (J2000)
POINT_DEC:       +54.874d {+54d 52' 27"} (J2000)
POINT_ROLL:      213.424d
IMG_START_DATE:  18518 TJD;    35 DOY;   19/02/04
IMG_START_TIME:  21056.58 SOD {05:50:56.58} UT,   290.5 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.979
N_STARS:         176
X_OFFSET:        613 [pixels]
Y_OFFSET:        656 [pixels]
X_MAX:           1572 [pixels]
Y_MAX:           1615 [pixels]
DET_THRESH:      9
PHOTO_THRESH:    4
SL_URL:          sw00887579000msufc0290.fits
SUN_POSTN:       317.58d {+21h 10m 20s}  -16.30d {-16d 17' 58"}
SUN_DIST:         76.94 [deg]   Sun_angle= -2.3 [hr] (East of Sun)
MOON_POSTN:      310.96d {+20h 43m 51s}  -19.24d {-19d 14' 18"}
MOON_DIST:        81.93 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      110.78, -5.97 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       23.50, 51.64 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 04 Feb 19 05:57:53 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     887579,   Seg_Num: 0
POINT_RA:        351.517d {+23h 26m 04s} (J2000)
POINT_DEC:       +54.874d {+54d 52' 27"} (J2000)
POINT_ROLL:      213.424d
IMG_START_DATE:  18518 TJD;    35 DOY;   19/02/04
IMG_START_TIME:  21056.58 SOD {05:50:56.58} UT,   290.5 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.979
N_STARS:         176
X_OFFSET:        613 [pixels]
Y_OFFSET:        656 [pixels]
X_MAX:           1572 [pixels]
Y_MAX:           1615 [pixels]
DET_THRESH:      9
PHOTO_THRESH:    4
SL_URL:          sw00887579000msufc0290.fits
SUN_POSTN:       317.58d {+21h 10m 20s}  -16.30d {-16d 17' 58"}
SUN_DIST:         76.94 [deg]   Sun_angle= -2.3 [hr] (East of Sun)
MOON_POSTN:      310.96d {+20h 43m 51s}  -19.24d {-19d 14' 17"}
MOON_DIST:        81.93 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      110.78, -5.97 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       23.50, 51.64 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 04 Feb 19 05:58:55 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     887579,   Seg_Num: 0
POINT_RA:        351.517d {+23h 26m 04s} (J2000)
POINT_DEC:       +54.874d {+54d 52' 27"} (J2000)
ROLL:            213.424d
IMG_START_DATE:  18518 TJD;    35 DOY;   19/02/04
IMG_START_TIME:  21056.58 SOD {05:50:56.58} UT,   290.5 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     570952278
X_OFFSET:        933 [pixels]
Y_OFFSET:        976 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1093
Y_GRB_POS:       1136
BINNING_INDEX:   1
IM_URL:          sw00887579000msuni0313.fits
SUN_POSTN:       317.58d {+21h 10m 20s}  -16.30d {-16d 17' 57"}
SUN_DIST:         76.94 [deg]   Sun_angle= -2.3 [hr] (East of Sun)
MOON_POSTN:      310.97d {+20h 43m 53s}  -19.24d {-19d 14' 11"}
MOON_DIST:        81.92 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      110.78, -5.97 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       23.50, 51.64 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 04 Feb 19 05:59:10 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     887579,   Seg_Num: 0
POINT_RA:        351.517d {+23h 26m 04s} (J2000)
POINT_DEC:       +54.874d {+54d 52' 27"} (J2000)
ROLL:            213.424d
IMG_START_DATE:  18518 TJD;    35 DOY;   19/02/04
IMG_START_TIME:  21056.58 SOD {05:50:56.58} UT,   290.5 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     570952278
X_OFFSET:        933 [pixels]
Y_OFFSET:        976 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1093
Y_GRB_POS:       1136
BINNING_INDEX:   1
IM_URL:          sw00887579000msuni0313.fits
SUN_POSTN:       317.58d {+21h 10m 20s}  -16.30d {-16d 17' 57"}
SUN_DIST:         76.94 [deg]   Sun_angle= -2.3 [hr] (East of Sun)
MOON_POSTN:      310.97d {+20h 43m 54s}  -19.24d {-19d 14' 10"}
MOON_DIST:        81.92 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      110.78, -5.97 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       23.50, 51.64 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 04 Feb 19 06:03:32 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     887579,   Seg_Num: 0
POINT_RA:        351.517d {+23h 26m 04s} (J2000)
POINT_DEC:       +54.874d {+54d 52' 27"} (J2000)
POINT_ROLL:      213.424d
IMG_START_DATE:  18518 TJD;    35 DOY;   19/02/04
IMG_START_TIME:  21634.74 SOD {06:00:34.74} UT,   868.7 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.863
N_STARS:         190
X_OFFSET:        373 [pixels]
Y_OFFSET:        416 [pixels]
X_MAX:           1812 [pixels]
Y_MAX:           1855 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    7
SL_URL:          sw00887579000msufc0868.fits
SUN_POSTN:       317.59d {+21h 10m 21s}  -16.30d {-16d 17' 53"}
SUN_DIST:         76.94 [deg]   Sun_angle= -2.3 [hr] (East of Sun)
MOON_POSTN:      311.01d {+20h 44m 03s}  -19.23d {-19d 13' 47"}
MOON_DIST:        81.90 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      110.78, -5.97 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       23.50, 51.64 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 04 Feb 19 06:03:45 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     887579,   Seg_Num: 0
POINT_RA:        351.517d {+23h 26m 04s} (J2000)
POINT_DEC:       +54.874d {+54d 52' 27"} (J2000)
POINT_ROLL:      213.424d
IMG_START_DATE:  18518 TJD;    35 DOY;   19/02/04
IMG_START_TIME:  21634.74 SOD {06:00:34.74} UT,   868.7 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.863
N_STARS:         190
X_OFFSET:        373 [pixels]
Y_OFFSET:        416 [pixels]
X_MAX:           1812 [pixels]
Y_MAX:           1855 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    7
SL_URL:          sw00887579000msufc0868.fits
SUN_POSTN:       317.59d {+21h 10m 21s}  -16.30d {-16d 17' 53"}
SUN_DIST:         76.94 [deg]   Sun_angle= -2.3 [hr] (East of Sun)
MOON_POSTN:      311.01d {+20h 44m 03s}  -19.23d {-19d 13' 46"}
MOON_DIST:        81.90 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      110.78, -5.97 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       23.50, 51.64 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 04 Feb 19 06:04:59 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     887579,   Seg_Num: 0
POINT_RA:        351.517d {+23h 26m 04s} (J2000)
POINT_DEC:       +54.874d {+54d 52' 27"} (J2000)
ROLL:            213.424d
IMG_START_DATE:  18518 TJD;    35 DOY;   19/02/04
IMG_START_TIME:  21634.74 SOD {06:00:34.74} UT,   868.7 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     570952857
X_OFFSET:        932 [pixels]
Y_OFFSET:        975 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1092
Y_GRB_POS:       1135
BINNING_INDEX:   1
IM_URL:          sw00887579000msuni0891.fits
SUN_POSTN:       317.59d {+21h 10m 21s}  -16.30d {-16d 17' 52"}
SUN_DIST:         76.94 [deg]   Sun_angle= -2.3 [hr] (East of Sun)
MOON_POSTN:      311.02d {+20h 44m 06s}  -19.23d {-19d 13' 40"}
MOON_DIST:        81.89 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      110.78, -5.97 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       23.50, 51.64 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 04 Feb 19 06:05:15 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     887579,   Seg_Num: 0
POINT_RA:        351.517d {+23h 26m 04s} (J2000)
POINT_DEC:       +54.874d {+54d 52' 27"} (J2000)
ROLL:            213.424d
IMG_START_DATE:  18518 TJD;    35 DOY;   19/02/04
IMG_START_TIME:  21634.74 SOD {06:00:34.74} UT,   868.7 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     570952857
X_OFFSET:        932 [pixels]
Y_OFFSET:        975 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1092
Y_GRB_POS:       1135
BINNING_INDEX:   1
IM_URL:          sw00887579000msuni0891.fits
SUN_POSTN:       317.59d {+21h 10m 21s}  -16.30d {-16d 17' 52"}
SUN_DIST:         76.94 [deg]   Sun_angle= -2.3 [hr] (East of Sun)
MOON_POSTN:      311.03d {+20h 44m 07s}  -19.23d {-19d 13' 39"}
MOON_DIST:        81.89 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      110.78, -5.97 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       23.50, 51.64 [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 #23852
A. Y. Lien (GSFC/UMBC), M. G. Bernardini (INAF-OAB), P. D'Avanzo (INAF-OAB), N. J. Klingler (PSU), A. Melandri (INAF-OAB), D. M. Palmer (LANL) and A. Tohuvavohu (PSU) report on behalf of the Neil Gehrels Swift Observatory Team:
At 05:46:01 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 190204A (trigger=887579 and 887580). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 351.514, +54.878 which is
```
   RA(J2000) = 23h 26m 03s
   Dec(J2000) = +54d 52' 42"
```
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 ~28000 counts/sec (15-350 keV), at ~5 sec after the trigger.
The XRT began observing the field at 05:47:15.7 UT, 75.0 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 351.47755, 54.87623 which is equivalent to:
```
   RA(J2000)  = 23h 25m 54.61s
   Dec(J2000) = +54d 52' 34.4"
```
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This location is 119 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 consistent with the Galactic value of 4.36 x 10^21 cm^-2 (Willingale et al. 2013).
The initial flux in the 2.5 s image was 5.72e-09 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 250 seconds with the U filter starting 295 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at
```
  RA(J2000)  =	23:25:54.58 = 351.47742
  DEC(J2000) = +54:52:34.9  =  54.87637
```
with a 90%-confidence error radius of about 0.63 arc sec. This position is 4.2 arc sec. from the center of the XRT error circle. The estimated magnitude is 17.76 with a 1-sigma error of about 0.15. No correction has been made for the expected extinction corresponding to E(B-V) of 0.38.
This GRB resulted in two BAT triggers in the on-board processing (#887579 at 05:46:01 and #887580 at 05:46:06). We adopt the first trigger number and time as T0.
Burst Advocate for this burst is A. Y. Lien (amy.y.lien AT nasa.gov). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: /too.html.)

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 04 Feb 19 06:23:18 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     887579,   Seg_Num: 0
GRB_RA:          351.4777d {+23h 25m 54.64s} (J2000),
                 351.7002d {+23h 26m 48.04s} (current),
                 350.8975d {+23h 23m 35.40s} (1950)
GRB_DEC:         +54.8764d {+54d 52' 35.0"} (J2000),
                 +54.9816d {+54d 58' 53.5"} (current),
                 +54.6013d {+54d 36' 04.6"} (1950)
GRB_ERROR:       3.6 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  18518 TJD;    35 DOY;   19/02/04
IMG_START_TIME:  21770.00 SOD {06:02:50.00} UT,   1004.0 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       317.60d {+21h 10m 24s}  -16.29d {-16d 17' 39"}
SUN_DIST:         76.92 [deg]   Sun_angle= -2.3 [hr] (East of Sun)
MOON_POSTN:      311.18d {+20h 44m 44s}  -19.20d {-19d 12' 05"}
MOON_DIST:        81.80 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:      110.76, -5.96 [deg] galactic lon,lat of the burst
ECL_COORDS:       23.48, 51.66 [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 Circular #23854
T. Oeda (Tokyo Tech), M. Nakajima (Nihon U.), S. Nakahira (RIKEN), H. Negoro, A. Sakamaki, W. Maruyama, M. Aoki, K. Kobayashi (Nihon U.), T. Mihara, F. Yatabe, Y. Takao, M. Matsuoka (RIKEN), T. Sakamoto, M. Serino, S. Sugita, T. Hashimoto, A. Yoshida (AGU), N. Kawai, M. Sugizaki, Y. Tachibana, K. Morita (Tokyo Tech), S. Ueno, H. Tomida, M. Ishikawa, Y. Sugawara, N. Isobe, R. Shimomukai, T. Midooka (JAXA), Y. Ueda, A. Tanimoto, T. Morita, S. Yamada, S. Ogawa (Kyoto U.), Y. Tsuboi, W. Iwakiri, R. Sasaki, H. Kawai, T. Sato (Chuo U.), H. Tsunemi, T. Yoneyama, K. Asakura, S. Ide (Osaka U.), M. Yamauchi, K. Hidaka, S. Iwahori (Miyazaki U.), T. Kawamuro (NAOJ), K. Yamaoka (Nagoya U.), M. Shidatsu (Ehime U.), Y. Kawakubo (LSU) report on behalf of the MAXI team:
The MAXI/GSC nova alert system triggered a bright X-ray transient at 05:45:55 UT on February 4, 2019. Assuming that the source flux was constant over the transit, we obtain the source position at (R.A., Dec) = (351.341 deg, 54.761 deg) = (23 25 21, +54 45 38) (J2000) with a 90% C.L. statistical error of 0.10 deg and an additional systematic uncertainty of 0.1 deg (90% containment radius). The X-ray flux averaged over the scan was 2286 +- 126 mCrab (4.0-10.0keV, 1 sigma error). Without assumptions on the source constancy,we obtain a rectangular error box for the transient source with the following corners:
```
(R.A., Dec) = (350.693, 54.635) deg = (23 22 46, +54 38 05) (J2000)
(R.A., Dec) = (350.828, 54.512) deg = (23 23 18, +54 30 43) (J2000)
(R.A., Dec) = (352.146, 54.985) deg = (23 28 35, +54 59 05) (J2000)
(R.A., Dec) = (352.013, 55.110) deg = (23 28 03, +55 06 35) (J2000).
```
The trigger time and position was consistent with that of GRB 190204A detected by Swift (Lien et al. 2019, GCN 23852).
GCN Circular #23856
T. Khanam, V. Sharma, D. Bhattacharya and A. Vibhute (IUCAA), V. Bhalerao (IIT-B), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:
Analysis of AstroSat CZTI data showed the detection of a long GRB 190204A, which was also detected by Swift (Lien A. Y. et al., GCN Circ 23852) and MAXI/GSC (Oeda T. et al., GCN Circ 23854).
The source was clearly detected in the 20-200 keV energy range. The light curve shows multiple peaks of emission with the strongest peak at 05:46:06.5 UT. The measured peak count rate is 1455 cts/s above the background in the combined data of four quadrants, with a total of 5579 cts. The local mean background count rate was 569 cts/s. Using cumulative rates, we measure a T90 of 11.9 s. In preliminary analysis, we find that 578 Compton events are associated with this event.
It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range.
CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.
GCN Circular #23857
J.A. Kennea (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), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU) and A.Y. Lien report on behalf of the Swift-XRT team:
We have analysed 6.4 ks of XRT data for GRB 190204A (Lien et al. GCN Circ. 23852), from 81 s to 13.0 ks after the BAT trigger. The data comprise 926 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The refined XRT position is RA, Dec = 351.4775, +54.8766 which is equivalent to:
```
RA (J2000): 23 25 54.59
Dec(J2000): +54 52 35.7
```
with an uncertainty of 3.6 arcsec (radius, 90% confidence).
The late-time light curve (from T0+4.8 ks) can be modelled with a power-law decay with a decay index of alpha=1.36 (+/-0.16).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.740 (+0.022, -0.018). The best-fitting absorption column is consistent with the Galactic value of 4.4 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.83 (+0.12, -0.11) and a best-fitting absorption column of 5.4 (+0.8, -0.7) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.6 x 10^-11 (6.8 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     5.4 (+0.8, -0.7) x 10^21 cm^-2
Galactic foreground: 4.4 x 10^21 cm^-2
Excess significance: 2.4 sigma
Photon index:	     1.83 (+0.12, -0.11)
```
If the light curve continues to decay with a power-law decay index of 1.36, the count rate at T+24 hours will be 9.9 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.5 x 10^-13 (6.8 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/00887579.
This circular is an official product of the Swift-XRT team.
GCN Circular #23861
Alan M. Watson (UNAM), Nat Butler (ASU), Rosa L. Becerra (UNAM), Diego Gonz�lez (UNAM), William H. Lee (UNAM), Margarita Pereyra (UNAM), Carlos Rom�n-Z��iga (UNAM), Alexander Kutyrev (GSFC), and Eleonora Troja (GSFC) report:
We observed the field of GRB 190204A (Lien et al., GCN Circ. 23852) with the COATLI 50-cm telescope and interim imager at the Observatorio Astron�mico Nacional on the Sierra de San Pedro M�rtir (http://coatli.astroscu.unam.mx) from 2019-02-04 05:46:35 to 2019-02-04 05:57:30 (from 34 to 689 seconds after the trigger), obtaining a total of 345 seconds of exposure in the w filter.
At the position of the UVOT afterglow candidate (Lien et al., GCN Circ. 23852), we detect a source that fades from w = 13.5 to w = 17.5 over the course of our observations. A power-law fit suggest a temporal index of -1.44 +/- 0.03.
Our w magnitudes are calibrated against the USNO-B1 catalog (adjusted to an approximate AB system) and are not corrected for Galactic extinction in the direction of the GRB.
We thank the COATLI technical team and the staff of the Observatorio Astron�mico Nacional.
GCN Circular #23862
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team.
Using 2532 s of XRT Photon Counting mode data and 6 UVOT images for GRB 190204A, 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 = 351.47820, +54.87637 which is equivalent to:
```
RA (J2000): 23h 25m 54.77s
Dec (J2000): +54d 52' 34.9"
```
with an uncertainty of 1.5 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 #23863
Paul Kuin (UCL/MSSL) and A. Y. Lien (GSFC/UMBC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 190204A 84 s after the BAT trigger (Lien et al., GCN Circ. 23852). The updated UVOT position is:
The preliminary UVOT position is: RA (J2000) = 23:25:54.58 = 351.47744 (deg.) Dec (J2000) = +54:52:35.1 = 54.87642 (deg.) with an estimated uncertainty of 0.4 arc sec. (radius, 90% confidence).
Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white               84          233          147         16.84 +/- 0.07
white              576          596           20         18.66 +/- 0.20
v                  626         1247           78         18.30 +/- 0.23
b                  551         1507           85         19.29 +/- 0.21
u                  296          546          246         17.85 +/- 0.10
w1                 676         1470           97        >18.3
m2                 651         1444           97        >19.5
w2                 602         1395           97        >18.7
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.38 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #23867
A. Volnova (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), R. Inasaridze (AbAO), E. Mazaeva (IKI), S. Belkin (IKI) report on behalf of IKI-GRB-FuN:
We observed the field of localization of GRB 190204A (Lien et al. GCN 23852) with AZT-33IK telescope of Sayan observatory (Mondy). We started observations on Feb. 04 (UT) 13:10:12 in R-filter. We do not detect the optical afterglow (Lien et al. GCN 23852; Watson et al., GCN 23861; Kuin et al., GCN 23863). Preliminary photometry of the field is following.
```
Date               UT start      t-T0          Filter Exp.   OT     Err.
  UL
                                         (mid, days)        (s)
                (3 sigma)

2019-02-04  13:10:12  0.32583     R      25*120      n/d     n/d   20.3
```
The photometry is based on nearby SDSS stars:
```
SDSS_id                         R_Lupton
J232549.70+545348.8 16.978 0.014
J232550.46+545253.5 17.052 0.014
J232544.33+545253.6 16.085 0.013
```
Our observation confirm rapid initial decay of the afterglow detected by UVOT (Kuin et al., GCN 23863).
GCN Circular #23868
A. S. Moskvitin (SAO RAS) report on behalf of larger GRB follow-up team.
We observed the field of the GRB 190204A (Lien et al., GCNC #23852) with the Zeiss-1000 telescope of SAO RAS (+ CCD photometer) on February, 4, 15:36:17--16:44:07 UT (mid. time 16:10:12). The observations were carried out in Rc band.
We detected the OT (Lien et al., GCNC #23852; Watson et al., GCNC #23861; Kuin & Lien, GCNC #23863) in the stacked 12 x 300 sec. image.
Preliminary brightness of OT is R = 21.9 +/- 0.1 (T-T0 = 0.4335 d). The calibrations is based on nearby SDSS stars (Volnova et al., GCNC #23867), magnitudes converted with the Lupton 2005 equations.
GCN Circular #23869
A. Kozlova, S. Golenetskii, R. Aptekar, D. Frederiks, M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline on behalf of the Konus-Wind team, report:
The long-duration GRB 190204A (Swift detection: Lien et al., GCN Circ. 23852; MAXI/GSC detection: Oeda et al., GCN Circ. 23854; AstroSat CZTI detection: Khanam et al., GCN Circ. 23856) triggered Konus-Wind at T0=20755.832 s UT (05:45:55.832).
The burst light curve shows a multipeaked structure started at ~T0-1 s with a total duration of ~49 s. The emission is seen up to ~10 MeV.
As observed by Konus-Wind, the burst had a fluence of 5.31(-0.51,+0.53)x10^-5 erg/cm2, and a 64-ms peak flux, measured from T0+8.288 s, of 2.17(-0.28,+0.29)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst (measured from T0 to T0+17.408 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.88(-0.07,+0.08), the high energy photon index beta = -2.43(-0.30,+0.18), the peak energy Ep = 308(-30,+33) keV (chi2 = 76/98 dof).
The spectrum near the maximum count rate (measured from T0+7.680 to T0+9.472 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.85(-0.07,+0.08), the high energy photon index beta = -2.70(-0.58,+0.25), the peak energy Ep = 387(-39,+46) keV (chi2 = 69/66 dof).
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB190204_T20755/
All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.
GCN Circular #23872
T. Sakamoto (AGU), 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), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-234 to T+968 sec from the recent telemetry downlink, we report further analysis of BAT GRB 190204A (trigger #887579 and #887580) (Lien et al., GCN Circ. 23852). In this circular, we adopted the trigger time from the first trigger (#887579), 2019-02-04 05:46:01 UT, to be consistent with the T0 quoted in other circulars. The BAT ground-calculated position is RA, Dec = 351.491, 54.884 deg which is
```
   RA(J2000)  =  23h 25m 57.8s
   Dec(J2000) = +54d 53' 02.4"
```
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 48%.
The mask-weighted light curve shows several overlapping pulses that starts at ~T-7 s and ends at ~T+55 s. The main peak occurs at ~T+5 s. T90 (15-350 keV) is 26.4 +- 7.5 sec (estimated error including systematics).
The time-averaged spectrum from T-6.93 to T+53.82 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.30 +- 0.04. The fluence in the 15-150 keV band is 1.3 +- 0.03 x 10^-5 erg/cm2. The 1-sec peak photon flux measured from T+4.55 sec in the 15-150 keV band is 30.5 +- 0.9 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/887580/BA/ (Please note that this page shows the automatic analysis from the 2nd trigger #887580, because BAT associated most of the data with this trigger ID. Thus, the T0 displayed in the webpage is 4.995 sec later than the trigger time referenced in this circular.)
GCN Circular #23877
T. Ito, A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita (AGU), Y. Kawakubo (LSU), A. Tezuka, S. Matsukawa, H. Onozawa, H. Morita, Y. Sone (AGU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), I. Takahashi (IPMU), Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), W. Ishizaki (ICRR), M. L. Cherry (LSU), S. Ricciarini (U of Florence), A. V. Penacchioni, P. S. Marrocchesi (U of Siena), and the CALET collaboration:
The long GRB 190204A (Swift-BAT triggers #887579 and #887580: Lien et al., GCN Circ. 23852, Sakamoto et al., GCN Circ.23872; MAXI/GSC detection: Oeda et al., GCN Circ. 23854; AstroSat CZTI detection: Khanam et al., GCN Circ. 23856; Konus-Wind observation: Kozlova et al., GCN Circ. 23869) triggered the CALET Gamma-ray Burst Monitor (CGBM) at 05:46:05.075 UTC on 4 February 2019. No real-time CGBM GCN notice was distributed about this trigger because the real-time communication from the ISS was off (loss of signal). The burst signal was seen by all CGBM detectors.
The burst light curve shows a single pulse which starts at T-7.7 sec, peaks at 1.1 sec and ends at T+5.8 sec. The T90 and T50 durations measured by the SGM data are 11.0 +- 2.0 sec and 2.2 +- 0.5 sec (40-1000 keV), respectively. The ground processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1233294225/
The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at the Waseda University.

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Jochen Greiner, last update: 06-Feb-2019 [Disclaimer]