Gamma-ray Burst 180904A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 04 Sep 18 21:29:32 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     859282,   Seg_Num: 0
GRB_RA:          274.250d {+18h 17m 00s} (J2000),
                 274.380d {+18h 17m 31s} (current),
                 273.904d {+18h 15m 37s} (1950)
GRB_DEC:         +46.623d {+46d 37' 24"} (J2000),
                 +46.631d {+46d 37' 52"} (current),
                 +46.603d {+46d 36' 12"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       19968 [cnts]    Image_Peak=382 [image_cnts]
TRIGGER_DUR:     5.504 [sec] 
TRIGGER_INDEX:   476     E_range: 25-100 keV
BKG_INTEN:       161428 [cnts]
BKG_TIME:        77242.45 SOD {21:27:22.45} UT
BKG_DUR:         48 [sec]
GRB_DATE:        18365 TJD;   247 DOY;   18/09/04
GRB_TIME:        77312.41 SOD {21:28:32.41} UT
GRB_PHI:         -48.40 [deg]
GRB_THETA:        30.31 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     10.00 [sigma]
IMAGE_SIGNIF:    8.12 [sigma]
MERIT_PARAMS:     +1  +0  +0  +2  +2  -2  +0  +0 +15  +0 
SUN_POSTN:       163.68d {+10h 54m 42s}   +6.95d {+06d 56' 46"}
SUN_DIST:         98.81 [deg]   Sun_angle= -7.4 [hr] (East of Sun)
MOON_POSTN:       95.95d {+06h 23m 47s}  +20.86d {+20d 51' 53"}
MOON_DIST:       112.49 [deg]
MOON_ILLUM:      30 [%]
GAL_COORDS:       74.40, 25.02 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      278.53, 69.94 [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 = 26.53,19.11 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 04 Sep 18 21:31:12 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     859282,   Seg_Num: 0
GRB_RA:          274.2506d {+18h 17m 00.1s} (J2000),
                 274.3801d {+18h 17m 31.2s} (current),
                 273.9039d {+18h 15m 36.9s} (1950)
GRB_DEC:         +46.6283d {+46d 37' 41.8"} (J2000),
                 +46.6361d {+46d 38' 10.0"} (current),
                 +46.6085d {+46d 36' 30.6"} (1950)
GRB_ERROR:       6.5 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       25 [cnts]
IMG_START_DATE:  18365 TJD;   247 DOY;   18/09/04
IMG_START_TIME:  77435.35 SOD {21:30:35.35} UT,   122.9 [sec] since BAT Trigger Time
CENTROID_X:      266.97,  raw= 267  [pixels]
CENTROID_Y:      292.99,  raw= 293  [pixels]
ROLL:            289.93 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -12.74
GRB_POS_XRT_Z:   -92.94
IMAGE_URL:       sw00859282000msxps_rw.img
SUN_POSTN:       163.68d {+10h 54m 42s}   +6.95d {+06d 56' 45"}
SUN_DIST:         98.80 [deg]   Sun_angle= -7.4 [hr] (East of Sun)
MOON_POSTN:       95.96d {+06h 23m 52s}  +20.87d {+20d 51' 56"}
MOON_DIST:       112.48 [deg]
MOON_ILLUM:      30 [%]
GAL_COORDS:       74.40, 25.02 [deg] galactic lon,lat of the burst
ECL_COORDS:      278.53, 69.94 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 04 Sep 18 21:31:00 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     859282,   Seg_Num: 0
GRB_RA:          274.2506d {+18h 17m 00.14s} (J2000),
                 274.3801d {+18h 17m 31.23s} (current),
                 273.9039d {+18h 15m 36.94s} (1950)
GRB_DEC:         +46.6283d {+46d 37' 41.8"} (J2000),
                 +46.6361d {+46d 38' 10.0"} (current),
                 +46.6085d {+46d 36' 30.6"} (1950)
GRB_ERROR:       6.6 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       4.47e-10 [erg/cm2/sec]
GRB_SIGNIF:      5.00 [sigma]
IMG_START_DATE:  18365 TJD;   247 DOY;   18/09/04
IMG_START_TIME:  77435.35 SOD {21:30:35.35} UT,   122.9 [sec] since BAT Trigger Time
TAM[0-3]:        327.63 237.19 261.60 243.63
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       163.68d {+10h 54m 42s}   +6.95d {+06d 56' 45"}
SUN_DIST:         98.80 [deg]   Sun_angle= -7.4 [hr] (East of Sun)
MOON_POSTN:       95.96d {+06h 23m 51s}  +20.87d {+20d 51' 55"}
MOON_DIST:       112.48 [deg]
MOON_ILLUM:      30 [%]
GAL_COORDS:       74.40, 25.02 [deg] galactic lon,lat of the burst
ECL_COORDS:      278.53, 69.94 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 0.31 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 04 Sep 18 21:32:16 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     859282,   Seg_Num: 0
GRB_RA:          274.250d {+18h 17m 00s} (J2000),
                 274.380d {+18h 17m 31s} (current),
                 273.904d {+18h 15m 37s} (1950)
GRB_DEC:         +46.623d {+46d 37' 24"} (J2000),
                 +46.631d {+46d 37' 52"} (current),
                 +46.603d {+46d 36' 12"} (1950)
GRB_DATE:        18365 TJD;   247 DOY;   18/09/04
GRB_TIME:        77312.41 SOD {21:28:32.41} UT
TRIGGER_INDEX:   476
GRB_PHI:         -48.40 [deg]
GRB_THETA:        30.31 [deg]
DELTA_TIME:      45.00 [sec]
TRIGGER_DUR:     5.504 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     10.00 [sigma]
IMAGE_SIGNIF:    8.12 [sigma]
LC_URL:          sw00859282000msb.lc
SUN_POSTN:       163.68d {+10h 54m 43s}   +6.95d {+06d 56' 44"}
SUN_DIST:         98.80 [deg]   Sun_angle= -7.4 [hr] (East of Sun)
MOON_POSTN:       95.98d {+06h 23m 54s}  +20.87d {+20d 51' 57"}
MOON_DIST:       112.49 [deg]
MOON_ILLUM:      30 [%]
GAL_COORDS:       74.40, 25.02 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      278.53, 69.94 [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 = 26.53,19.11 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 04 Sep 18 21:31:10 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     859282,   Seg_Num: 0
GRB_RA:          274.2506d {+18h 17m 00.1s} (J2000),
                 274.3801d {+18h 17m 31.2s} (current),
                 273.9039d {+18h 15m 36.9s} (1950)
GRB_DEC:         +46.6283d {+46d 37' 41.8"} (J2000),
                 +46.6361d {+46d 38' 10.0"} (current),
                 +46.6085d {+46d 36' 30.6"} (1950)
GRB_ERROR:       6.5 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       25 [cnts]
IMG_START_DATE:  18365 TJD;   247 DOY;   18/09/04
IMG_START_TIME:  77435.35 SOD {21:30:35.35} UT,   122.9 [sec] since BAT Trigger Time
CENTROID_X:      266.97,  raw= 267  [pixels]
CENTROID_Y:      292.99,  raw= 293  [pixels]
ROLL:            289.93 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -12.74
GRB_POS_XRT_Z:   -92.94
IMAGE_URL:       sw00859282000msxps_rw.img
SUN_POSTN:       163.68d {+10h 54m 42s}   +6.95d {+06d 56' 45"}
SUN_DIST:         98.80 [deg]   Sun_angle= -7.4 [hr] (East of Sun)
MOON_POSTN:       95.96d {+06h 23m 51s}  +20.87d {+20d 51' 56"}
MOON_DIST:       112.48 [deg]
MOON_ILLUM:      30 [%]
GAL_COORDS:       74.40, 25.02 [deg] galactic lon,lat of the burst
ECL_COORDS:      278.53, 69.94 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 04 Sep 18 21:33:34 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     859282,   Seg_Num: 0
POINT_RA:        274.284d {+18h 17m 08s} (J2000)
POINT_DEC:       +46.617d {+46d 36' 59"} (J2000)
POINT_ROLL:      289.930d
IMG_START_DATE:  18365 TJD;   247 DOY;   18/09/04
IMG_START_TIME:  77443.69 SOD {21:30:43.69} UT,   131.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.316
N_STARS:         71
X_OFFSET:        640 [pixels]
Y_OFFSET:        464 [pixels]
X_MAX:           1599 [pixels]
Y_MAX:           1423 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00859282000msufc0131.fits
SUN_POSTN:       163.68d {+10h 54m 43s}   +6.95d {+06d 56' 43"}
SUN_DIST:         98.83 [deg]   Sun_angle= -7.4 [hr] (East of Sun)
MOON_POSTN:       95.99d {+06h 23m 58s}  +20.87d {+20d 51' 59"}
MOON_DIST:       112.49 [deg]
MOON_ILLUM:      30 [%]
GAL_COORDS:       74.39, 25.00 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      278.60, 69.93 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 04 Sep 18 21:33:50 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     859282,   Seg_Num: 0
POINT_RA:        274.284d {+18h 17m 08s} (J2000)
POINT_DEC:       +46.617d {+46d 36' 59"} (J2000)
POINT_ROLL:      289.930d
IMG_START_DATE:  18365 TJD;   247 DOY;   18/09/04
IMG_START_TIME:  77443.69 SOD {21:30:43.69} UT,   131.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.316
N_STARS:         71
X_OFFSET:        640 [pixels]
Y_OFFSET:        464 [pixels]
X_MAX:           1599 [pixels]
Y_MAX:           1423 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00859282000msufc0131.fits
SUN_POSTN:       163.68d {+10h 54m 43s}   +6.95d {+06d 56' 42"}
SUN_DIST:         98.83 [deg]   Sun_angle= -7.4 [hr] (East of Sun)
MOON_POSTN:       95.99d {+06h 23m 58s}  +20.87d {+20d 51' 59"}
MOON_DIST:       112.49 [deg]
MOON_ILLUM:      30 [%]
GAL_COORDS:       74.39, 25.00 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      278.60, 69.93 [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:     Tue 04 Sep 18 21:34:49 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     859282,   Seg_Num: 0
POINT_RA:        274.284d {+18h 17m 08s} (J2000)
POINT_DEC:       +46.617d {+46d 36' 59"} (J2000)
ROLL:            289.930d
IMG_START_DATE:  18365 TJD;   247 DOY;   18/09/04
IMG_START_TIME:  77443.69 SOD {21:30:43.69} UT,   131.3 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     557789465
X_OFFSET:        984 [pixels]
Y_OFFSET:        809 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1144
Y_GRB_POS:       969
BINNING_INDEX:   1
IM_URL:          sw00859282000msuni0153.fits
SUN_POSTN:       163.68d {+10h 54m 43s}   +6.94d {+06d 56' 42"}
SUN_DIST:         98.83 [deg]   Sun_angle= -7.4 [hr] (East of Sun)
MOON_POSTN:       96.00d {+06h 24m 01s}  +20.87d {+20d 52' 01"}
MOON_DIST:       112.49 [deg]
MOON_ILLUM:      30 [%]
GAL_COORDS:       74.39, 25.00 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      278.60, 69.93 [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:     Tue 04 Sep 18 21:34:55 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     859282,   Seg_Num: 0
POINT_RA:        274.284d {+18h 17m 08s} (J2000)
POINT_DEC:       +46.617d {+46d 36' 59"} (J2000)
ROLL:            289.930d
IMG_START_DATE:  18365 TJD;   247 DOY;   18/09/04
IMG_START_TIME:  77443.69 SOD {21:30:43.69} UT,   131.3 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     557789465
X_OFFSET:        984 [pixels]
Y_OFFSET:        809 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1144
Y_GRB_POS:       969
BINNING_INDEX:   1
IM_URL:          sw00859282000msuni0153.fits
SUN_POSTN:       163.68d {+10h 54m 43s}   +6.94d {+06d 56' 41"}
SUN_DIST:         98.83 [deg]   Sun_angle= -7.4 [hr] (East of Sun)
MOON_POSTN:       96.00d {+06h 24m 01s}  +20.87d {+20d 52' 01"}
MOON_DIST:       112.49 [deg]
MOON_ILLUM:      30 [%]
GAL_COORDS:       74.39, 25.00 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      278.60, 69.93 [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:     Tue 04 Sep 18 21:40:48 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     859282,   Seg_Num: 0
POINT_RA:        274.286d {+18h 17m 09s} (J2000)
POINT_DEC:       +46.615d {+46d 36' 54"} (J2000)
POINT_ROLL:      289.930d
IMG_START_DATE:  18365 TJD;   247 DOY;   18/09/04
IMG_START_TIME:  77601.76 SOD {21:33:21.76} UT,   289.3 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.333
N_STARS:         54
X_OFFSET:        664 [pixels]
Y_OFFSET:        489 [pixels]
X_MAX:           1623 [pixels]
Y_MAX:           1448 [pixels]
DET_THRESH:      6
PHOTO_THRESH:    2
SL_URL:          sw00859282000msufc0289.fits
SUN_POSTN:       163.68d {+10h 54m 44s}   +6.94d {+06d 56' 36"}
SUN_DIST:         98.83 [deg]   Sun_angle= -7.4 [hr] (East of Sun)
MOON_POSTN:       96.07d {+06h 24m 16s}  +20.87d {+20d 52' 09"}
MOON_DIST:       112.49 [deg]
MOON_ILLUM:      30 [%]
GAL_COORDS:       74.39, 24.99 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      278.60, 69.93 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 04 Sep 18 21:41:02 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     859282,   Seg_Num: 0
POINT_RA:        274.286d {+18h 17m 09s} (J2000)
POINT_DEC:       +46.615d {+46d 36' 54"} (J2000)
POINT_ROLL:      289.930d
IMG_START_DATE:  18365 TJD;   247 DOY;   18/09/04
IMG_START_TIME:  77601.76 SOD {21:33:21.76} UT,   289.3 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.333
N_STARS:         54
X_OFFSET:        664 [pixels]
Y_OFFSET:        489 [pixels]
X_MAX:           1623 [pixels]
Y_MAX:           1448 [pixels]
DET_THRESH:      6
PHOTO_THRESH:    2
SL_URL:          sw00859282000msufc0289.fits
SUN_POSTN:       163.68d {+10h 54m 44s}   +6.94d {+06d 56' 36"}
SUN_DIST:         98.83 [deg]   Sun_angle= -7.4 [hr] (East of Sun)
MOON_POSTN:       96.07d {+06h 24m 17s}  +20.87d {+20d 52' 09"}
MOON_DIST:       112.49 [deg]
MOON_ILLUM:      30 [%]
GAL_COORDS:       74.39, 24.99 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      278.60, 69.93 [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:     Tue 04 Sep 18 21:41:56 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     859282,   Seg_Num: 0
POINT_RA:        274.286d {+18h 17m 09s} (J2000)
POINT_DEC:       +46.615d {+46d 36' 54"} (J2000)
ROLL:            289.930d
IMG_START_DATE:  18365 TJD;   247 DOY;   18/09/04
IMG_START_TIME:  77601.76 SOD {21:33:21.76} UT,   289.3 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     557789623
X_OFFSET:        984 [pixels]
Y_OFFSET:        809 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1144
Y_GRB_POS:       969
BINNING_INDEX:   1
IM_URL:          sw00859282000msuni0311.fits
SUN_POSTN:       163.68d {+10h 54m 44s}   +6.94d {+06d 56' 35"}
SUN_DIST:         98.83 [deg]   Sun_angle= -7.4 [hr] (East of Sun)
MOON_POSTN:       96.08d {+06h 24m 19s}  +20.87d {+20d 52' 11"}
MOON_DIST:       112.49 [deg]
MOON_ILLUM:      30 [%]
GAL_COORDS:       74.39, 24.99 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      278.60, 69.93 [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:     Tue 04 Sep 18 21:42:11 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     859282,   Seg_Num: 0
POINT_RA:        274.286d {+18h 17m 09s} (J2000)
POINT_DEC:       +46.615d {+46d 36' 54"} (J2000)
ROLL:            289.930d
IMG_START_DATE:  18365 TJD;   247 DOY;   18/09/04
IMG_START_TIME:  77601.76 SOD {21:33:21.76} UT,   289.3 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     557789623
X_OFFSET:        984 [pixels]
Y_OFFSET:        809 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1144
Y_GRB_POS:       969
BINNING_INDEX:   1
IM_URL:          sw00859282000msuni0311.fits
SUN_POSTN:       163.68d {+10h 54m 44s}   +6.94d {+06d 56' 35"}
SUN_DIST:         98.83 [deg]   Sun_angle= -7.4 [hr] (East of Sun)
MOON_POSTN:       96.08d {+06h 24m 20s}  +20.87d {+20d 52' 11"}
MOON_DIST:       112.49 [deg]
MOON_ILLUM:      30 [%]
GAL_COORDS:       74.39, 24.99 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      278.60, 69.93 [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:     Tue 04 Sep 18 21:41:25 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     859282,   Seg_Num: 0
GRB_RA:          274.2495d {+18h 17m 00.11s} (J2000),
                 274.3790d {+18h 17m 30.96s} (current),
                 273.9028d {+18h 15m 36.68s} (1950)
GRB_DEC:         +46.6298d {+46d 37' 47.2"} (J2000),
                 +46.6376d {+46d 38' 15.4"} (current),
                 +46.6100d {+46d 36' 36.0"} (1950)
GRB_ERROR:       2.3 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  18365 TJD;   247 DOY;   18/09/04
IMG_START_TIME:  77534.00 SOD {21:32:14.00} UT,   221.6 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       163.68d {+10h 54m 44s}   +6.94d {+06d 56' 35"}
SUN_DIST:         98.80 [deg]   Sun_angle= -7.4 [hr] (East of Sun)
MOON_POSTN:       96.07d {+06h 24m 18s}  +20.87d {+20d 52' 10"}
MOON_DIST:       112.48 [deg]
MOON_ILLUM:      30 [%]
GAL_COORDS:       74.40, 25.02 [deg] galactic lon,lat of the burst
ECL_COORDS:      278.53, 69.94 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        This is an Update Notice -- the RA,Dec values herein supersede the previous XRT_POS Notice.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        This position was enhanced using UVOT field astrometry.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.11% < P(seren) < 0.58%.

GCN Circular #23194
A. D'Ai (INAF-IASFPA), J.D. Gropp (PSU), J. A. Kennea (PSU), S. J. LaPorte (PSU), A. Y. Lien (GSFC/UMBC), M. J. Moss (George Washington University), D. M. Palmer (LANL), B. Sbarufatti (PSU) and A. Tohuvavohu (PSU) report on behalf of the Neil Gehrels Swift Observatory Team:
At 21:28:32 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 180904A (trigger=859282). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 274.250, +46.623 which is
```
   RA(J2000) = 18h 17m 00s
   Dec(J2000) = +46d 37' 24"
```
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 ~5 sec after the trigger.
The XRT began observing the field at 21:30:35.3 UT, 123.0 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source with an enhanced position: RA, Dec 274.2495, 46.6298 which is equivalent to:
```
   RA(J2000)  = 18h 16m 59.87s
   Dec(J2000) = +46d 37' 47.4"
```
with an uncertainty of 2.3 arcseconds (radius, 90% containment). This location is 24 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.
A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (3.37 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 3.3 (+3.26/-2.80) x 10^21 cm^-2 (90% confidence).
The initial flux in the 2.5 s image was 4.47e-10 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 131 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 0.04.
Burst Advocate for this burst is A. D'Ai (antonino.dai AT ifc.inaf.it). 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 Circular #23195
Daniele Malesani (DAWN/NBI and DARK/NBI), Kasper Elm Heintz (Univ. Iceland and DAWN/NBI), Sune Dyrbye (NOT), report on behalf of a largert collaboration:
We observed the field of GRB 180904A (D'Ai' et al., GCN 23194) with the Nordic Optical Telescope (NOT) equipped with the AlFOSC camera.
In an image of 300 s exposure taken with the SDSS r filter and commencing on Sep 4.9057 UT (15.6 min after the GRB), we detect a single object consistent with the currently available XRT position (http://www.swift.ac.uk/xrt_positions/). Its coordinates are (J2000):
```
RA = 18:16:59.74
Dec = +46:37:47.1
```
Compared to nearby stars from the Pan-STARRS survey, we measure for this object a magnitude r = 22.56 +- 0.08 AB.
We note that the same object is visible in the archival Pan-STARRS image of this field, with a measured magnitude r = 22.84 +- 0.15 AB. There is thus only marginal indication of excess flux in the NOT image. If this object is related to GRB 180904A, as suggested by the spatial coincidence with the X-ray position, it is largely or entirely dominated by the host galaxy.
Further observations are planned.
GCN Circular #23196
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team.
Using 468 s of XRT Photon Counting mode data and 1 UVOT images for GRB 180904A, 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 = 274.24978, +46.62971 which is equivalent to:
```
RA (J2000): 18h 16m 59.95s
Dec (J2000): +46d 37' 46.9"
```
with an uncertainty of 1.8 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177).
This circular was automatically generated, and is an official product of the Swift-XRT team.
GCN Circular #23197
L. Izzo, D. A. Kann, A. de Ugarte Postigo, C.C. Thoene (all HETH/IAA-CSIC), and F. Aceituno (IAA-CSIC) report:
We observed the field of GRB 180904A (D’Ai et al., GCN #23194) with the 1.5-m OSN telescope in Granada, Spain. We obtained 12 x 300 s images in the Ic band centered at 1.23 hours after the GRB.
At the enhanced XRT position of the GRB (Osborne et al., GCN #23196), we find no source inside the Swift-XRT error circle down to a limit of Ic (AB) > 22.4. We note, however, that the object reported in Malesani et al., GCN #23195, lies just outside the XRT position reported by Osborne et al., and may therefore be unrelated to the GRB.
The calibration was performed using i-band magnitudes of nearby stars in the Pan-STARRS catalog, transformed into Ic magnitudes according to the Lupton (2005) transformations.
GCN Circular #23198
Moskvitin, A. S., Spiridonova O. I., Maslennikova O. A. (SAO RAS), report on behalf of larger GRB follow-up team.
We observed the field of the GRB 180904A (D'Ai et al., GCNC 23194) with the Zeiss-1000 telescope of SAO RAS (+ CCD UBVRcIc photometer) on the 2018 September, 4.926 (mid. time).
The observations started since 7.2 minutes after the Swift trigger (21:35:44--22:46:03 UT). 12 x 300 sec. exposures in Rc band were obtained. We can not see any object inside the XRT enhanced 1".8 error circle (Osborne et al., GCNC 23196) down to the limiting magnitude of R_lim = 22.7, but at the edge of the circle we detected the object mentioned by Malesani et al. (GCNC 23195). The preliminary magnitude of the object is R = 21.9 +/- 0.2 (Vega system) compared to nearby USNO-B1 stars.
The finding chart can be found at ftp://ftp.sao.ru/pub/grb/GRB/GRB180904A_SAORAS.png
GCN Circular #23199
C. Guidorzi, R. Martone (U. Ferrara), S. Kobayashi (LJMU), C.G. Mundell (U. Bath), A. Gomboc (U. Nova Gorica), I.A. Steele (LJMU) on behalf of a large collaboration report:
The 2-m robotic Liverpool Telescope automatically began observing Swift GRB 180904A (D'Ai et al. GCN 23194) with the polarimeter RINGO3 and the IO:O camera on September 04, 21:32:12 UT (219 seconds from the GRB trigger time). Within the enhanced Swift-XRT error circle (Osborne et al. GCN 23196) we do not detect any object down to a limit of r' > 21.2 mag in a 6x10s exposure at a mid time of 37 minutes post burst, as calibrated against nearby Pan-STARRS objects, in agreement with previous reports (Malesani et al. GCN 23195; Izzo et al. GCN 23197; Moskvitin et al. GCN 23198).
GCN Circular #23200
K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), A. Tohuvavohu (PSU), P.A. Evans (U. Leicester) and A. D'Ai report on behalf of the Swift-XRT team:
We have analysed 6.5 ks of XRT data for GRB 180904A (D'Ai et al. GCN Circ. 23194), from 129 s to 45.0 ks after the BAT trigger. The data comprise 91 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. 23196).
The light curve can be modelled with a series of power-law decays. The initial decay index is alpha=0.9 (+0.4, -0.6). At T+179 s the decay steepens to an alpha of 7.84 (+0.16, -1.21) before breaking again at T+247 s to a final decay with index alpha=1.19 (+/-0.15).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.61 (+0.24, -0.22). The best-fitting absorption column is 4.6 (+1.0, -0.9) x 10^21 cm^-2, in excess of the Galactic value of 3.4 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 2.19 (+0.26, -0.24) and a best-fitting absorption column of 4.3 (+1.2, -1.1) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.6 x 10^-11 (6.4 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     4.3 (+1.2, -1.1) x 10^21 cm^-2
Galactic foreground: 3.4 x 10^20 cm^-2
Excess significance: 6.0 sigma
Photon index:	     2.19 (+0.26, -0.24)
```
If the light curve continues to decay with a power-law decay index of 1.19, the count rate at T+24 hours will be 7.3 x 10^-4 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.6 x 10^-14 (4.6 x 10^-14) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00859282.
This circular is an official product of the Swift-XRT team.
GCN Circular #23203
D. M. Palmer (LANL), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), A. D'Ai (INAF-IASFPA), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 180904A (trigger #859282) (D'Ai et al., GCN Circ. 23194). The BAT ground-calculated position is RA, Dec = 274.260, 46.640 deg which is
```
  RA(J2000)  =  18h 17m 02.4s
  Dec(J2000) = +46d 38' 23.3"
```
with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 56%.
The mask-weighted light curve shows a weak structure that starts at ~T0 and ends at ~T+6 s. T90 (15-350 keV) is 5.40 +- 0.89 sec (estimated error including systematics).
The time-averaged spectrum from T+0.28 to T+6.18 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.02 +- 0.30. The fluence in the 15-150 keV band is 2.4 +- 0.4 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+5.14 sec in the 15-150 keV band is 0.5 +- 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/859282/BA/
GCN Circular #23204
Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), Jes�s Gonz�lez (UNAM), Carlos Rom�n-Z��iga (UNAM), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.), and Vicki Toy (UMD) report:
We observed the field of GRB 180904A (D'Ai, et al., GCN 23194) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astron�mico Nacional on Sierra San Pedro M�rtir from 2018/09 5.13 to 2018/09 5.32 UTC (5.66 to 10.26 hours after the BAT trigger), obtaining a total of 2.91 hours exposure in the r and i bands and 1.33 hours exposure in the Z, Y, J, and H bands.
Within the XRT error circle (Osborne, et al., GCN 23196), we detect the source reported by Malesani, et al. (GCN 23195) at a consistent brightness level. In comparison with the USNO-B1 and 2MASS catalogs, we obtain the following detections and upper limit (3-sigma):
```
 r = 22.61 +/- 0.08
 i = 22.06 +/- 0.05
 Z = 22.13 +/- 0.16
 Y = 21.64 +/- 0.18
 J = 21.72 +/- 0.21
 H > 21.86
```
These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB.
We thank the staff of the Observatorio Astron�mico Nacional in San Pedro M�rtir.
GCN Circular #23205
M. H. Siegel (PSU) and A. D'Ai (INAF-IASFPA) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 180904A 131 s after the BAT trigger (D'Ai et al., GCN Circ. 23194). No optical afterglow consistent with the XRT position (Osborne et al. GCN Circ. 23196) is detected in the initial UVOT exposures, consistent with the non-detections of Malesani et al. (GCN Circ. 23195), Izzy et al. (GCN Circ 23197), Moskvitin et al. (GCN Circ. 23198) and Guidorzi et al. (GCN Circ. 23199). 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           131          281          147         >21.1
u_FC               289          539          246         >20.1
white              131          589          167         >21.1
v                  620          640           19         >20.1
b                  545          565           19         >19.4
u                  289          539          246         >20.1
w1                 670          690           19         >18.1
w2                 595          615           19         >18.6
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.04 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #23206
A. Volnova (IKI), A. Pozanenko (IKI), R. Inasaridze (AbAO), E. Mazaeva (IKI), V. Ayvazian (AbAO), O. Kvaratskhelia (AbAO), G. Kapanadze (AbAO), I. Molotov (KIAM) report on behalf of larger GRB follow-up collaboration:
We observed the field of the Swift GRB 180904A (D'Ai et al., GCN 23194) with AS-32 (0.7m) telescope of Abastumani Observatory starting on September 04 (UT) 21:52:23. We do not detect any object within enhanced XRT position (Osborne et al., GCN 23196). Preliminary photometry of the field is following:
```
Date        UT start   t-T0      Filter Exp.   OT    Err. UL
                      (mid, days)        (s)

2018-09-04  21:52:23   0.05731   CR     70*60  n/d   n/d  21.5
```
The photometry is based on nearby USNO-B1.0 stars (R2 magnitude)
```
USNO-B.1_id    R2
1366-0296056   14.72
1366-0296068   15.43
1365-0287325   15.62
1366-0296106   15.21
1366-0296088   14.95
1366-0296093   14.37
```
GCN Circular #23209
C. Perez del Pulgar, A. Castellon, I. Carrasco (Univ. de Malaga), Y.-D. Hu, E. Fernandez-Garcia, J. C. Tello, A. Ayala, A. J. Castro-Tirado (IAA-CSIC), and M. Jelinek (ASU-CAS), on behalf of a larger collaboration, report:
The 60cm BOOTES-2/TELMA robotic telescope at IHSM La Mayora (UMA-CSIC) in Algarrobo Costa (Spain) automatically responded in 56s (and 116s after the GRB onset) to the Swift trigger of GRB 180904A (D'Ai et al. GCNC 23194). The first image (11s exposure, unfiltered) was obtained at 21:30:28 UT. At the position of the enhanced Swift X-ray afterglow (Osborne et al. GCNC 23196), no optical afterglow is detected down to 19 mag at a mid time of 6 minutes post burst. This is consistent with the limits reported by Malesani et al. (GCNC 23195), Izzo et al. (GCNC 23197), Moskvitin et al. (GCNC 23198, Guidorzi et al. (GCNC 23199), Butler et al. (GCNC 23204), Siegel et al. (GCNC 23205), Volnova et al. (GCNC 23206).

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Jochen Greiner, last update: 06-Sep-2018 [Disclaimer]