Gamma-ray Burst 171004A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 04 Oct 17 08:08:47 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     776347,   Seg_Num: 0
GRB_RA:          139.162d {+09h 16m 39s} (J2000),
                 139.474d {+09h 17m 54s} (current),
                 138.279d {+09h 13m 07s} (1950)
GRB_DEC:         +52.680d {+52d 40' 48"} (J2000),
                 +52.605d {+52d 36' 18"} (current),
                 +52.889d {+52d 53' 21"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       0 [cnts]    Image_Peak=3009 [image_cnts]
TRIGGER_DUR:     88.000 [sec] 
TRIGGER_INDEX:   20000     E_range: 15-50 keV
BKG_INTEN:       0 [cnts]
BKG_TIME:        0.00 SOD {00:00:00.00} UT
BKG_DUR:         0 [sec]
GRB_DATE:        18030 TJD;   277 DOY;   17/10/04
GRB_TIME:        28532.21 SOD {07:55:32.21} UT
GRB_PHI:          -6.10 [deg]
GRB_THETA:        44.63 [deg]
SOLN_STATUS:     0x13
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    15.15 [sigma]
MERIT_PARAMS:     +1  +0  +0  +6  +1  +4  +0  +0 -31  +0 
SUN_POSTN:       190.39d {+12h 41m 33s}   -4.47d {-04d 28' 04"}
SUN_DIST:         71.35 [deg]   Sun_angle= 3.4 [hr] (West of Sun)
MOON_POSTN:      354.40d {+23h 37m 37s}   -5.10d {-05d 06' 16"}
MOON_DIST:       124.51 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:      164.86, 43.01 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      124.00, 34.89 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Coordinates.  
COMMENTS:        This Notice was delayed by more than 60 sec past the end of the trigger integration interval;  
COMMENTS:        probably due to it occurring during a Malindi downlink session.  
COMMENTS:        This is an image trigger.  (The RATE_SIGNIF & BKG_{INTEN, TIME, DUR} are undefined.)  
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 = 78.43,18.33 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 04 Oct 17 08:09:32 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     776347,   Seg_Num: 0
GRB_RA:          139.1713d {+09h 16m 41.1s} (J2000),
                 139.4833d {+09h 17m 55.9s} (current),
                 138.2889d {+09h 13m 09.3s} (1950)
GRB_DEC:         +52.6937d {+52d 41' 37.3"} (J2000),
                 +52.6187d {+52d 37' 07.3"} (current),
                 +52.9030d {+52d 54' 10.6"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       107 [cnts]
IMG_START_DATE:  18030 TJD;   277 DOY;   17/10/04
IMG_START_TIME:  28706.90 SOD {07:58:26.90} UT,   174.7 [sec] since BAT Trigger Time
CENTROID_X:      343.94,  raw= 344  [pixels]
CENTROID_Y:      343.87,  raw= 344  [pixels]
ROLL:            125.01 [deg]
GAIN:            2
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   107.20
GRB_POS_XRT_Z:   88.50
IMAGE_URL:       sw00776347000msxps_rw.img
SUN_POSTN:       190.39d {+12h 41m 33s}   -4.47d {-04d 28' 05"}
SUN_DIST:         71.35 [deg]   Sun_angle= 3.4 [hr] (West of Sun)
MOON_POSTN:      354.41d {+23h 37m 39s}   -5.10d {-05d 06' 08"}
MOON_DIST:       124.50 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:      164.84, 43.01 [deg] galactic lon,lat of the burst
ECL_COORDS:      124.00, 34.90 [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:     Wed 04 Oct 17 08:09:20 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     776347,   Seg_Num: 0
GRB_RA:          139.1713d {+09h 16m 41.11s} (J2000),
                 139.4833d {+09h 17m 55.98s} (current),
                 138.2889d {+09h 13m 09.32s} (1950)
GRB_DEC:         +52.6937d {+52d 41' 37.3"} (J2000),
                 +52.6187d {+52d 37' 07.3"} (current),
                 +52.9030d {+52d 54' 10.6"} (1950)
GRB_ERROR:       4.9 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       3.22e-09 [erg/cm2/sec]
GRB_SIGNIF:      10.34 [sigma]
IMG_START_DATE:  18030 TJD;   277 DOY;   17/10/04
IMG_START_TIME:  28706.90 SOD {07:58:26.90} UT,   174.7 [sec] since BAT Trigger Time
TAM[0-3]:        327.67 237.20 261.62 243.46
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       190.39d {+12h 41m 33s}   -4.47d {-04d 28' 05"}
SUN_DIST:         71.35 [deg]   Sun_angle= 3.4 [hr] (West of Sun)
MOON_POSTN:      354.41d {+23h 37m 38s}   -5.10d {-05d 06' 10"}
MOON_DIST:       124.50 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:      164.84, 43.01 [deg] galactic lon,lat of the burst
ECL_COORDS:      124.00, 34.90 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 0.89 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:     Wed 04 Oct 17 08:09:37 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     776347,   Seg_Num: 0
GRB_RA:          139.1713d {+09h 16m 41.1s} (J2000),
                 139.4833d {+09h 17m 55.9s} (current),
                 138.2889d {+09h 13m 09.3s} (1950)
GRB_DEC:         +52.6937d {+52d 41' 37.3"} (J2000),
                 +52.6187d {+52d 37' 07.3"} (current),
                 +52.9030d {+52d 54' 10.6"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       107 [cnts]
IMG_START_DATE:  18030 TJD;   277 DOY;   17/10/04
IMG_START_TIME:  28706.90 SOD {07:58:26.90} UT,   174.7 [sec] since BAT Trigger Time
CENTROID_X:      343.94,  raw= 344  [pixels]
CENTROID_Y:      343.87,  raw= 344  [pixels]
ROLL:            125.01 [deg]
GAIN:            2
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   107.20
GRB_POS_XRT_Z:   88.50
IMAGE_URL:       sw00776347000msxps_rw.img
SUN_POSTN:       190.39d {+12h 41m 33s}   -4.47d {-04d 28' 05"}
SUN_DIST:         71.35 [deg]   Sun_angle= 3.4 [hr] (West of Sun)
MOON_POSTN:      354.41d {+23h 37m 39s}   -5.10d {-05d 06' 07"}
MOON_DIST:       124.50 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:      164.84, 43.01 [deg] galactic lon,lat of the burst
ECL_COORDS:      124.00, 34.90 [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:     Wed 04 Oct 17 08:10:22 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     776347,   Seg_Num: 0
POINT_RA:        139.176d {+09h 16m 42s} (J2000)
POINT_DEC:       +52.655d {+52d 39' 18"} (J2000)
POINT_ROLL:      125.012d
IMG_START_DATE:  18030 TJD;   277 DOY;   17/10/04
IMG_START_TIME:  28716.59 SOD {07:58:36.59} UT,   184.4 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.222
N_STARS:         13
X_OFFSET:        288 [pixels]
Y_OFFSET:        544 [pixels]
X_MAX:           1247 [pixels]
Y_MAX:           1503 [pixels]
DET_THRESH:      15
PHOTO_THRESH:    8
SL_URL:          sw00776347000msufc0184.fits
SUN_POSTN:       190.39d {+12h 41m 33s}   -4.47d {-04d 28' 06"}
SUN_DIST:         71.33 [deg]   Sun_angle= 3.4 [hr] (West of Sun)
MOON_POSTN:      354.42d {+23h 37m 40s}   -5.10d {-05d 05' 59"}
MOON_DIST:       124.53 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:      164.89, 43.02 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      124.02, 34.87 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 04 Oct 17 08:10:40 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     776347,   Seg_Num: 0
POINT_RA:        139.176d {+09h 16m 42s} (J2000)
POINT_DEC:       +52.655d {+52d 39' 18"} (J2000)
POINT_ROLL:      125.012d
IMG_START_DATE:  18030 TJD;   277 DOY;   17/10/04
IMG_START_TIME:  28716.59 SOD {07:58:36.59} UT,   184.4 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.222
N_STARS:         13
X_OFFSET:        288 [pixels]
Y_OFFSET:        544 [pixels]
X_MAX:           1247 [pixels]
Y_MAX:           1503 [pixels]
DET_THRESH:      15
PHOTO_THRESH:    8
SL_URL:          sw00776347000msufc0184.fits
SUN_POSTN:       190.39d {+12h 41m 33s}   -4.47d {-04d 28' 06"}
SUN_DIST:         71.33 [deg]   Sun_angle= 3.4 [hr] (West of Sun)
MOON_POSTN:      354.42d {+23h 37m 41s}   -5.10d {-05d 05' 55"}
MOON_DIST:       124.53 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:      164.89, 43.02 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      124.02, 34.87 [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:     Wed 04 Oct 17 08:11:44 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     776347,   Seg_Num: 0
POINT_RA:        139.176d {+09h 16m 42s} (J2000)
POINT_DEC:       +52.655d {+52d 39' 18"} (J2000)
ROLL:            125.012d
IMG_START_DATE:  18030 TJD;   277 DOY;   17/10/04
IMG_START_TIME:  28716.59 SOD {07:58:36.59} UT,   184.4 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     528796736
X_OFFSET:        538 [pixels]
Y_OFFSET:        784 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       698
Y_GRB_POS:       944
BINNING_INDEX:   1
IM_URL:          sw00776347000msuni0204.fits
SUN_POSTN:       190.39d {+12h 41m 33s}   -4.47d {-04d 28' 07"}
SUN_DIST:         71.33 [deg]   Sun_angle= 3.4 [hr] (West of Sun)
MOON_POSTN:      354.43d {+23h 37m 43s}   -5.10d {-05d 05' 44"}
MOON_DIST:       124.52 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:      164.89, 43.02 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      124.02, 34.87 [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:     Wed 04 Oct 17 08:11:58 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     776347,   Seg_Num: 0
POINT_RA:        139.176d {+09h 16m 42s} (J2000)
POINT_DEC:       +52.655d {+52d 39' 18"} (J2000)
ROLL:            125.012d
IMG_START_DATE:  18030 TJD;   277 DOY;   17/10/04
IMG_START_TIME:  28716.59 SOD {07:58:36.59} UT,   184.4 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     528796736
X_OFFSET:        538 [pixels]
Y_OFFSET:        784 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       698
Y_GRB_POS:       944
BINNING_INDEX:   1
IM_URL:          sw00776347000msuni0204.fits
SUN_POSTN:       190.39d {+12h 41m 33s}   -4.47d {-04d 28' 07"}
SUN_DIST:         71.33 [deg]   Sun_angle= 3.4 [hr] (West of Sun)
MOON_POSTN:      354.43d {+23h 37m 44s}   -5.10d {-05d 05' 41"}
MOON_DIST:       124.52 [deg]
MOON_ILLUM:      97 [%]
GAL_COORDS:      164.89, 43.02 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      124.02, 34.87 [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:        If you have elected to receive attachments:  
COMMENTS:        The uvot_catalog_image.fits.gz file does not exist; skipping the attachment.

GCN Circular #21966
S. B. Cenko (GSFC), S. D. Barthelmy (GSFC), A. P. Beardmore (U Leicester), A. A. Breeveld (UCL-MSSL), P. A. Evans (U Leicester), J.D. Gropp (PSU), K. L. Page (U Leicester) and M. H. Siegel (PSU) report on behalf of the Swift Team:
At 07:55:32 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 171004A (trigger=776347). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 139.162, +52.680, which is
```
   RA(J2000)  =  09h 16m 39s
   Dec(J2000) = +52d 40' 48"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). As is typical for image triggers, there is nothing significant in the real-time light curve.
The XRT began observing the field at 07:58:26.9 UT, 174.7 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 139.1713, 52.6937 which is equivalent to:
```
   RA(J2000)  = +09h 16m 41.11s
   Dec(J2000) = +52d 41' 37.3"
```
with an uncertainty of 4.9 arcseconds (radius, 90% containment). This location is 53 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy.
The initial flux in the 2.5 s image was 3.22e-09 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 52 seconds with the White filter starting 184 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 0.02.
Burst Advocate for this burst is S. B. Cenko (brad.cenko 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: http://www.swift.psu.edu/too.html.)

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 04 Oct 17 08:57:18 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     776347,   Seg_Num: 0
POINT_RA:        139.119d {+09h 16m 28s} (J2000)
POINT_DEC:       +52.686d {+52d 41' 11"} (J2000)
POINT_ROLL:      124.962d
IMG_START_DATE:  18030 TJD;   277 DOY;   17/10/04
IMG_START_TIME:  32071.34 SOD {08:54:31.34} UT,   3539.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.059
N_STARS:         35
X_OFFSET:        536 [pixels]
Y_OFFSET:        328 [pixels]
X_MAX:           1495 [pixels]
Y_MAX:           1287 [pixels]
DET_THRESH:      12
PHOTO_THRESH:    6
SL_URL:          sw00776347000msufc3539.fits
SUN_POSTN:       190.42d {+12h 41m 40s}   -4.48d {-04d 28' 51"}
SUN_DIST:         71.40 [deg]   Sun_angle= 3.4 [hr] (West of Sun)
MOON_POSTN:      354.84d {+23h 39m 21s}   -4.96d {-04d 57' 23"}
MOON_DIST:       124.17 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      164.85, 42.98 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      123.97, 34.88 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 04 Oct 17 08:57:27 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     776347,   Seg_Num: 0
POINT_RA:        139.119d {+09h 16m 28s} (J2000)
POINT_DEC:       +52.686d {+52d 41' 11"} (J2000)
POINT_ROLL:      124.962d
IMG_START_DATE:  18030 TJD;   277 DOY;   17/10/04
IMG_START_TIME:  32071.34 SOD {08:54:31.34} UT,   3539.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.059
N_STARS:         35
X_OFFSET:        536 [pixels]
Y_OFFSET:        328 [pixels]
X_MAX:           1495 [pixels]
Y_MAX:           1287 [pixels]
DET_THRESH:      12
PHOTO_THRESH:    6
SL_URL:          sw00776347000msufc3539.fits
SUN_POSTN:       190.42d {+12h 41m 40s}   -4.48d {-04d 28' 51"}
SUN_DIST:         71.40 [deg]   Sun_angle= 3.4 [hr] (West of Sun)
MOON_POSTN:      354.84d {+23h 39m 21s}   -4.96d {-04d 57' 22"}
MOON_DIST:       124.17 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      164.85, 42.98 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      123.97, 34.88 [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:     Wed 04 Oct 17 08:58:55 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     776347,   Seg_Num: 0
POINT_RA:        139.119d {+09h 16m 28s} (J2000)
POINT_DEC:       +52.686d {+52d 41' 11"} (J2000)
ROLL:            124.962d
IMG_START_DATE:  18030 TJD;   277 DOY;   17/10/04
IMG_START_TIME:  32071.34 SOD {08:54:31.34} UT,   3539.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     528800091
X_OFFSET:        855 [pixels]
Y_OFFSET:        647 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1015
Y_GRB_POS:       807
BINNING_INDEX:   1
IM_URL:          sw00776347000msuni3559.fits
SUN_POSTN:       190.42d {+12h 41m 40s}   -4.48d {-04d 28' 53"}
SUN_DIST:         71.40 [deg]   Sun_angle= 3.4 [hr] (West of Sun)
MOON_POSTN:      354.85d {+23h 39m 24s}   -4.95d {-04d 57' 05"}
MOON_DIST:       124.16 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      164.85, 42.98 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      123.97, 34.88 [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:     Wed 04 Oct 17 08:59:05 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     776347,   Seg_Num: 0
POINT_RA:        139.119d {+09h 16m 28s} (J2000)
POINT_DEC:       +52.686d {+52d 41' 11"} (J2000)
ROLL:            124.962d
IMG_START_DATE:  18030 TJD;   277 DOY;   17/10/04
IMG_START_TIME:  32071.34 SOD {08:54:31.34} UT,   3539.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     528800091
X_OFFSET:        855 [pixels]
Y_OFFSET:        647 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1015
Y_GRB_POS:       807
BINNING_INDEX:   1
IM_URL:          sw00776347000msuni3559.fits
SUN_POSTN:       190.42d {+12h 41m 40s}   -4.48d {-04d 28' 53"}
SUN_DIST:         71.40 [deg]   Sun_angle= 3.4 [hr] (West of Sun)
MOON_POSTN:      354.85d {+23h 39m 25s}   -4.95d {-04d 57' 04"}
MOON_DIST:       124.16 [deg]
MOON_ILLUM:      98 [%]
GAL_COORDS:      164.85, 42.98 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      123.97, 34.88 [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 #21968
Alan M. Watson (UNAM), Nat Butler (ASU), 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=FAs Gonz=E1lez (UNAM), Carlos Rom=E1n-Z=FA=F1iga (UNAM), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.), and Vicki Toy (UMD) report:
We observed the field of GRB 171004A (Cenko et al., GCN Circ. 21966) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astron=F3mico Nacional on Sierra San Pedro M=E1rtir from 2017/10 4.45 to 2017/10 4.45 to 2017/10 4.52 UTC (2.97 to 4.45 hours after the BAT trigger), obtaining a total of 1.07 hours exposure in the r and i bands and 0.45 hours exposure in the Z, Y, J, and H bands.
We detect two sources within the Swift-XRT error circle. One is a cataloged SDSS source. The other is at 09:16:40.66 +52:41:30.4 (J2000 +/- 0.5 arcsec) and, in comparison with the SDSS DR9 and 2MASS catalogs, has
```
  r	=3D 21.91 +/- 0.11
  i	=3D 21.32 +/- 0.07
  Z	=3D 21.13 +/- 0.15
  Y	=3D 20.43 +/- 0.12
  J	=3D 20.45 +/- 0.15
  H	=3D 19.88 +/- 0.13
```
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=F3mico Nacional in San Pedro M=E1rtir.
GCN Circular #21970
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team.
Using 2218 s of XRT Photon Counting mode data and 2 UVOT images for GRB 171004A, 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 = 139.16941, +52.69319 which is equivalent to:
```
RA (J2000): 09h 16m 40.66s
Dec (J2000): +52d 41' 35.5"
```
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 #21971
A.P. Beardmore (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), S. J. LaPorte (PSU), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), P.A. Evans (U. Leicester), S.L. Gibson (U. Leicester) and S.B. Cenko report on behalf of the Swift-XRT team:
We have analysed 7.5 ks of XRT data for GRB 171004A (Cenko et al. GCN Circ. 21966), from 164 s to 17.4 ks after the BAT trigger. The data comprise 296 s in Windowed Timing (WT) mode (the first 9 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN Circ. 21970).
The light curve can be modelled with a series of power-law decays. The initial decay index is alpha=1.1 (+/-0.4). At T+205 s the decay steepens to an alpha of 4.1 (+0.9, -0.8). The light curve breaks again at T+524 s to a decay with alpha=0.3 (+0.5, -1.3), before a final break at T+5520 s s after which the decay index is 2.25 (+0.26, -0.16).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.25 (+/-0.08). The best-fitting absorption column is 2.41 (+0.28, -0.27) x 10^21 cm^-2, in excess of the Galactic value of 1.5 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.98 (+/-0.11) and a best-fitting absorption column of 8.8 (+2.8, -2.7) x 10^20 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.3 x 10^-11 (4.0 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     8.8 (+2.8, -2.7) x 10^20 cm^-2
Galactic foreground: 1.5 x 10^20 cm^-2
Excess significance: 4.5 sigma
Photon index:	     1.98 (+/-0.11)
```
If the light curve continues to decay with a power-law decay index of 2.25, the count rate at T+24 hours will be 2.1 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.9 x 10^-14 (8.3 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/00776347.
This circular is an official product of the Swift-XRT team.
GCN Circular #21972
Alan M. Watson (UNAM), Nat Butler (ASU), 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=FAs Gonz=E1lez (UNAM), Carlos Rom=E1n-Z=FA=F1iga (UNAM), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.), and Vicki Toy (UMD) report:
The position and magnitudes of the uncataloged source reported by Watson et al. (GCN Circ. 21968) are incorrect. We thank David Alexander Kann for drawing our attention to this error.
The correct position is RA, Dec =3D 139.169462 52.693080 (J2000) or 09:16:40.67 +52:41:35.1. This position lies 0.4 arcsec from the enhanced XRT position (Osborne et al., GCN Circ. 21970).
The correct magnitudes are
```
 r	=3D 21.17 +/- 0.06
 i	=3D 20.87 +/- 0.05
 Z	=3D 20.72 +/- 0.10
 Y	=3D 20.59 +/- 0.13
 J	=3D 20.36 +/- 0.14
 H	=3D 20.17 +/- 0.17
```
A fit to the i-band light curve of the source shows that the flux behaves as t^(-0.9+/-0.4). That is, it is fading at the 2-sigma level.
The positional coincidence combined with the weak evidence for fading suggest that this source might well be the afterglow of the GRB.
GCN Circular #21973
T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC), S. B. Cenko (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 171004A (trigger #776347) (Cenko et al., GCN Circ. 21966). The BAT ground-calculated position is RA, Dec = 139.150, 52.684 deg which is
```
   RA(J2000)  =  09h 16m 35.9s 
   Dec(J2000) = +52d 41' 01.5" 
```
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment). The partial coding was 42%.
The mask-weighted light curve shows several overlapping peaks that starts at ~ T+9 and ends at ~ T+160 s. The burst location went out of the BAT FOV at ~ T+580 s, and thus we only have information of the burst emission before then. T90 (15-350 keV) is 107.1 +- 14.5 sec (estimated error including systematics).
The time-averaged spectrum from T+9.08 to T+138.31 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.67 +- 0.12. The fluence in the 15-150 keV band is 3.0 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+48.34 sec in the 15-150 keV band is 0.9 +- 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/776347/BA/
GCN Circular #21974
J. D. Gropp (PSU) and S. B. Cenko (GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 171004A 184 s after the BAT trigger (Cenko et al., GCN Circ. 21966). No optical afterglow consistent with the refined XRT position (Osborne et al. GCN Circ. 21970) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the initial exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white              184         4143          233         >20.3
b                 3903         4103          197         >19.8
u                 3698         3898          197         >19.7
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.02 in the direction of the burst (Schlegel et al. 1998).

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Jochen Greiner, last update: 05-Oct-2017 [Disclaimer]