Gamma-ray Burst 171027A

(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:     Fri 27 Oct 17 08:23:49 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     783479,   Seg_Num: 0
GRB_RA:           61.680d {+04h 06m 43s} (J2000),
                  61.905d {+04h 07m 37s} (current),
                  61.051d {+04h 04m 12s} (1950)
GRB_DEC:          -2.606d {-02d 36' 21"} (J2000),
                  -2.559d {-02d 33' 32"} (current),
                  -2.739d {-02d 44' 21"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       13272 [cnts]    Image_Peak=476 [image_cnts]
TRIGGER_DUR:     4.096 [sec] 
TRIGGER_INDEX:   307     E_range: 50-350 keV
BKG_INTEN:       104864 [cnts]
BKG_TIME:        30132.09 SOD {08:22:12.09} UT
BKG_DUR:         40 [sec]
GRB_DATE:        18053 TJD;   300 DOY;   17/10/27
GRB_TIME:        30186.62 SOD {08:23:06.62} UT
GRB_PHI:          37.48 [deg]
GRB_THETA:        17.72 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     19.41 [sigma]
IMAGE_SIGNIF:    10.64 [sigma]
MERIT_PARAMS:     +1  +0  +0  +2  +3  +0  +0  +0 +83  +0 
SUN_POSTN:       211.86d {+14h 07m 26s}  -12.89d {-12d 53' 14"}
SUN_DIST:        146.41 [deg]   Sun_angle= 10.0 [hr] (West of Sun)
MOON_POSTN:      299.44d {+19h 57m 46s}  -18.67d {-18d 40' 16"}
MOON_DIST:       119.58 [deg]
MOON_ILLUM:      44 [%]
GAL_COORDS:      193.89,-37.31 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       59.00,-23.05 [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 = 256.65,16.40 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 27 Oct 17 08:24:58 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     783479,   Seg_Num: 0
GRB_RA:           61.6900d {+04h 06m 45.59s} (J2000),
                  61.9144d {+04h 07m 39.44s} (current),
                  61.0610d {+04h 04m 14.62s} (1950)
GRB_DEC:          -2.6221d {-02d 37' 19.5"} (J2000),
                  -2.5752d {-02d 34' 30.7"} (current),
                  -2.7555d {-02d 45' 19.7"} (1950)
GRB_ERROR:       4.7 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.36e-08 [erg/cm2/sec]
GRB_SIGNIF:      17.02 [sigma]
IMG_START_DATE:  18053 TJD;   300 DOY;   17/10/27
IMG_START_TIME:  30274.18 SOD {08:24:34.18} UT,   87.6 [sec] since BAT Trigger Time
TAM[0-3]:        327.66 237.22 261.66 243.62
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       211.86d {+14h 07m 26s}  -12.89d {-12d 53' 15"}
SUN_DIST:        146.39 [deg]   Sun_angle= 10.0 [hr] (West of Sun)
MOON_POSTN:      299.45d {+19h 57m 49s}  -18.67d {-18d 40' 12"}
MOON_DIST:       119.58 [deg]
MOON_ILLUM:      44 [%]
GAL_COORDS:      193.92,-37.31 [deg] galactic lon,lat of the burst
ECL_COORDS:       59.01,-23.07 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 1.12 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:     Fri 27 Oct 17 08:25:12 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     783479,   Seg_Num: 0
GRB_RA:           61.6900d {+04h 06m 45.5s} (J2000),
                  61.9144d {+04h 07m 39.4s} (current),
                  61.0610d {+04h 04m 14.6s} (1950)
GRB_DEC:          -2.6221d {-02d 37' 19.5"} (J2000),
                  -2.5752d {-02d 34' 30.7"} (current),
                  -2.7555d {-02d 45' 19.7"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       290 [cnts]
IMG_START_DATE:  18053 TJD;   300 DOY;   17/10/27
IMG_START_TIME:  30274.18 SOD {08:24:34.18} UT,   87.6 [sec] since BAT Trigger Time
CENTROID_X:      304.88,  raw= 305  [pixels]
CENTROID_Y:      279.35,  raw= 279  [pixels]
ROLL:            118.32 [deg]
GAIN:            8
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -44.89
GRB_POS_XRT_Z:   -3.56
IMAGE_URL:       sw00783479000msxps_rw.img
SUN_POSTN:       211.86d {+14h 07m 26s}  -12.89d {-12d 53' 15"}
SUN_DIST:        146.39 [deg]   Sun_angle= 10.0 [hr] (West of Sun)
MOON_POSTN:      299.45d {+19h 57m 49s}  -18.67d {-18d 40' 11"}
MOON_DIST:       119.58 [deg]
MOON_ILLUM:      44 [%]
GAL_COORDS:      193.92,-37.31 [deg] galactic lon,lat of the burst
ECL_COORDS:       59.01,-23.07 [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:     Fri 27 Oct 17 08:25:11 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     783479,   Seg_Num: 0
GRB_RA:           61.6900d {+04h 06m 45.5s} (J2000),
                  61.9144d {+04h 07m 39.4s} (current),
                  61.0610d {+04h 04m 14.6s} (1950)
GRB_DEC:          -2.6221d {-02d 37' 19.5"} (J2000),
                  -2.5752d {-02d 34' 30.7"} (current),
                  -2.7555d {-02d 45' 19.7"} (1950)
GRB_ERROR:       4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       290 [cnts]
IMG_START_DATE:  18053 TJD;   300 DOY;   17/10/27
IMG_START_TIME:  30274.18 SOD {08:24:34.18} UT,   87.6 [sec] since BAT Trigger Time
CENTROID_X:      304.88,  raw= 305  [pixels]
CENTROID_Y:      279.35,  raw= 279  [pixels]
ROLL:            118.32 [deg]
GAIN:            8
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -44.89
GRB_POS_XRT_Z:   -3.56
IMAGE_URL:       sw00783479000msxps_rw.img
SUN_POSTN:       211.86d {+14h 07m 26s}  -12.89d {-12d 53' 15"}
SUN_DIST:        146.39 [deg]   Sun_angle= 10.0 [hr] (West of Sun)
MOON_POSTN:      299.45d {+19h 57m 49s}  -18.67d {-18d 40' 11"}
MOON_DIST:       119.58 [deg]
MOON_ILLUM:      44 [%]
GAL_COORDS:      193.92,-37.31 [deg] galactic lon,lat of the burst
ECL_COORDS:       59.01,-23.07 [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:     Fri 27 Oct 17 08:26:46 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     783479,   Seg_Num: 0
GRB_RA:           61.680d {+04h 06m 43s} (J2000),
                  61.905d {+04h 07m 37s} (current),
                  61.051d {+04h 04m 12s} (1950)
GRB_DEC:          -2.606d {-02d 36' 21"} (J2000),
                  -2.559d {-02d 33' 32"} (current),
                  -2.739d {-02d 44' 21"} (1950)
GRB_DATE:        18053 TJD;   300 DOY;   17/10/27
GRB_TIME:        30186.62 SOD {08:23:06.62} UT
TRIGGER_INDEX:   307
GRB_PHI:          37.48 [deg]
GRB_THETA:        17.72 [deg]
DELTA_TIME:      -11.00 [sec]
TRIGGER_DUR:     4.096 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     19.41 [sigma]
IMAGE_SIGNIF:    10.64 [sigma]
LC_URL:          sw00783479000msb.lc
SUN_POSTN:       211.86d {+14h 07m 26s}  -12.89d {-12d 53' 17"}
SUN_DIST:        146.41 [deg]   Sun_angle= 10.0 [hr] (West of Sun)
MOON_POSTN:      299.47d {+19h 57m 52s}  -18.67d {-18d 40' 06"}
MOON_DIST:       119.56 [deg]
MOON_ILLUM:      45 [%]
GAL_COORDS:      193.89,-37.31 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       59.00,-23.05 [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 = 256.65,16.40 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 27 Oct 17 08:27:33 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     783479,   Seg_Num: 0
POINT_RA:         61.694d {+04h 06m 47s} (J2000)
POINT_DEC:        -2.611d {-02d 36' 38"} (J2000)
POINT_ROLL:      118.318d
IMG_START_DATE:  18053 TJD;   300 DOY;   17/10/27
IMG_START_TIME:  30282.50 SOD {08:24:42.50} UT,   95.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.149
N_STARS:         67
X_OFFSET:        392 [pixels]
Y_OFFSET:        640 [pixels]
X_MAX:           1351 [pixels]
Y_MAX:           1599 [pixels]
DET_THRESH:      12
PHOTO_THRESH:    6
SL_URL:          sw00783479000msufc0095.fits
SUN_POSTN:       211.86d {+14h 07m 26s}  -12.89d {-12d 53' 17"}
SUN_DIST:        146.40 [deg]   Sun_angle= 10.0 [hr] (West of Sun)
MOON_POSTN:      299.47d {+19h 57m 54s}  -18.67d {-18d 40' 03"}
MOON_DIST:       119.57 [deg]
MOON_ILLUM:      45 [%]
GAL_COORDS:      193.91,-37.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       59.02,-23.06 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 27 Oct 17 08:27:49 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     783479,   Seg_Num: 0
POINT_RA:         61.694d {+04h 06m 47s} (J2000)
POINT_DEC:        -2.611d {-02d 36' 38"} (J2000)
POINT_ROLL:      118.318d
IMG_START_DATE:  18053 TJD;   300 DOY;   17/10/27
IMG_START_TIME:  30282.50 SOD {08:24:42.50} UT,   95.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.149
N_STARS:         67
X_OFFSET:        392 [pixels]
Y_OFFSET:        640 [pixels]
X_MAX:           1351 [pixels]
Y_MAX:           1599 [pixels]
DET_THRESH:      12
PHOTO_THRESH:    6
SL_URL:          sw00783479000msufc0095.fits
SUN_POSTN:       211.86d {+14h 07m 26s}  -12.89d {-12d 53' 18"}
SUN_DIST:        146.40 [deg]   Sun_angle= 10.0 [hr] (West of Sun)
MOON_POSTN:      299.48d {+19h 57m 55s}  -18.67d {-18d 40' 02"}
MOON_DIST:       119.56 [deg]
MOON_ILLUM:      45 [%]
GAL_COORDS:      193.91,-37.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       59.02,-23.06 [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:     Fri 27 Oct 17 08:29:01 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     783479,   Seg_Num: 0
POINT_RA:         61.694d {+04h 06m 47s} (J2000)
POINT_DEC:        -2.611d {-02d 36' 38"} (J2000)
ROLL:            118.318d
IMG_START_DATE:  18053 TJD;   300 DOY;   17/10/27
IMG_START_TIME:  30282.50 SOD {08:24:42.50} UT,   95.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     530785502
X_OFFSET:        845 [pixels]
Y_OFFSET:        964 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1005
Y_GRB_POS:       1124
BINNING_INDEX:   1
IM_URL:          sw00783479000msuni0115.fits
SUN_POSTN:       211.86d {+14h 07m 27s}  -12.89d {-12d 53' 19"}
SUN_DIST:        146.40 [deg]   Sun_angle= 10.0 [hr] (West of Sun)
MOON_POSTN:      299.49d {+19h 57m 57s}  -18.67d {-18d 39' 58"}
MOON_DIST:       119.55 [deg]
MOON_ILLUM:      45 [%]
GAL_COORDS:      193.91,-37.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       59.02,-23.06 [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:     Fri 27 Oct 17 08:29:07 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     783479,   Seg_Num: 0
POINT_RA:         61.694d {+04h 06m 47s} (J2000)
POINT_DEC:        -2.611d {-02d 36' 38"} (J2000)
ROLL:            118.318d
IMG_START_DATE:  18053 TJD;   300 DOY;   17/10/27
IMG_START_TIME:  30282.50 SOD {08:24:42.50} UT,   95.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     530785502
X_OFFSET:        845 [pixels]
Y_OFFSET:        964 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1005
Y_GRB_POS:       1124
BINNING_INDEX:   1
IM_URL:          sw00783479000msuni0115.fits
SUN_POSTN:       211.86d {+14h 07m 27s}  -12.89d {-12d 53' 19"}
SUN_DIST:        146.40 [deg]   Sun_angle= 10.0 [hr] (West of Sun)
MOON_POSTN:      299.49d {+19h 57m 57s}  -18.67d {-18d 39' 58"}
MOON_DIST:       119.55 [deg]
MOON_ILLUM:      45 [%]
GAL_COORDS:      193.91,-37.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       59.02,-23.06 [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:     Fri 27 Oct 17 08:36:07 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     783479,   Seg_Num: 0
POINT_RA:         61.697d {+04h 06m 47s} (J2000)
POINT_DEC:        -2.610d {-02d 36' 34"} (J2000)
POINT_ROLL:      118.316d
IMG_START_DATE:  18053 TJD;   300 DOY;   17/10/27
IMG_START_TIME:  30494.46 SOD {08:28:14.46} UT,   307.8 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.615
N_STARS:         7
X_OFFSET:        525 [pixels]
Y_OFFSET:        644 [pixels]
X_MAX:           1484 [pixels]
Y_MAX:           1603 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw00783479000msufc0307.fits
SUN_POSTN:       211.87d {+14h 07m 28s}  -12.89d {-12d 53' 25"}
SUN_DIST:        146.40 [deg]   Sun_angle= 10.0 [hr] (West of Sun)
MOON_POSTN:      299.55d {+19h 58m 12s}  -18.66d {-18d 39' 33"}
MOON_DIST:       119.50 [deg]
MOON_ILLUM:      45 [%]
GAL_COORDS:      193.91,-37.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       59.02,-23.06 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 27 Oct 17 08:36:16 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     783479,   Seg_Num: 0
POINT_RA:         61.697d {+04h 06m 47s} (J2000)
POINT_DEC:        -2.610d {-02d 36' 34"} (J2000)
POINT_ROLL:      118.316d
IMG_START_DATE:  18053 TJD;   300 DOY;   17/10/27
IMG_START_TIME:  30494.46 SOD {08:28:14.46} UT,   307.8 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.615
N_STARS:         7
X_OFFSET:        525 [pixels]
Y_OFFSET:        644 [pixels]
X_MAX:           1484 [pixels]
Y_MAX:           1603 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw00783479000msufc0307.fits
SUN_POSTN:       211.87d {+14h 07m 28s}  -12.89d {-12d 53' 25"}
SUN_DIST:        146.40 [deg]   Sun_angle= 10.0 [hr] (West of Sun)
MOON_POSTN:      299.55d {+19h 58m 12s}  -18.66d {-18d 39' 33"}
MOON_DIST:       119.50 [deg]
MOON_ILLUM:      45 [%]
GAL_COORDS:      193.91,-37.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       59.02,-23.06 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        If you have elected to receive attachments:  
COMMENTS:        The uvot_catalog_srclist.fits.gz file does not exist; skipping the attachment.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 27 Oct 17 08:37:29 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     783479,   Seg_Num: 0
POINT_RA:         61.697d {+04h 06m 47s} (J2000)
POINT_DEC:        -2.610d {-02d 36' 34"} (J2000)
ROLL:            118.316d
IMG_START_DATE:  18053 TJD;   300 DOY;   17/10/27
IMG_START_TIME:  30494.46 SOD {08:28:14.46} UT,   307.8 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     530785714
X_OFFSET:        845 [pixels]
Y_OFFSET:        964 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1005
Y_GRB_POS:       1124
BINNING_INDEX:   1
IM_URL:          sw00783479000msuni0327.fits
SUN_POSTN:       211.87d {+14h 07m 28s}  -12.89d {-12d 53' 26"}
SUN_DIST:        146.40 [deg]   Sun_angle= 10.0 [hr] (West of Sun)
MOON_POSTN:      299.56d {+19h 58m 15s}  -18.66d {-18d 39' 29"}
MOON_DIST:       119.49 [deg]
MOON_ILLUM:      45 [%]
GAL_COORDS:      193.91,-37.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       59.02,-23.06 [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:     Fri 27 Oct 17 08:37:43 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     783479,   Seg_Num: 0
POINT_RA:         61.697d {+04h 06m 47s} (J2000)
POINT_DEC:        -2.610d {-02d 36' 34"} (J2000)
ROLL:            118.316d
IMG_START_DATE:  18053 TJD;   300 DOY;   17/10/27
IMG_START_TIME:  30494.46 SOD {08:28:14.46} UT,   307.8 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     530785714
X_OFFSET:        845 [pixels]
Y_OFFSET:        964 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1005
Y_GRB_POS:       1124
BINNING_INDEX:   1
IM_URL:          sw00783479000msuni0327.fits
SUN_POSTN:       211.87d {+14h 07m 28s}  -12.89d {-12d 53' 26"}
SUN_DIST:        146.40 [deg]   Sun_angle= 10.0 [hr] (West of Sun)
MOON_POSTN:      299.56d {+19h 58m 15s}  -18.66d {-18d 39' 28"}
MOON_DIST:       119.49 [deg]
MOON_ILLUM:      45 [%]
GAL_COORDS:      193.91,-37.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       59.02,-23.06 [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 #22053
P. D'Avanzo (INAF-OAB), P. A. Evans (U Leicester), N. P. M. Kuin (UCL-MSSL), K. L. Page (U Leicester), D. M. Palmer (LANL) and B. Sbarufatti (PSU) report on behalf of the Swift Team:
At 08:23:06 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 171027A (trigger=783479). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 61.680, -2.606 which is
```
   RA(J2000) = 04h 06m 43s
   Dec(J2000) = -02d 36' 21"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multiple-peaked structure with a duration of about 120 sec. The peak count rate was ~4000 counts/sec (15-350 keV), at ~60 sec after the trigger.
The XRT began observing the field at 08:24:34.1 UT, 87.6 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source located at RA, Dec 61.68989, -2.62100 which is equivalent to:
```
   RA(J2000)  = 04h 06m 45.57s
   Dec(J2000) = -02d 37' 15.6"
```
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This location is 64 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper.
A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (1.08 x 10^21 cm^-2, Willingale et al. 2013), with an excess column of 2.9 (+2.47/-2.17) x 10^21 cm^-2 (90% confidence).
The initial flux in the 2.5 s image was 1.36e-08 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 95 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 0.14.
Burst Advocate for this burst is P. D'Avanzo (paolo.davanzo AT brera.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 NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 27 Oct 17 08:42:03 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     783479,   Seg_Num: 0
POINT_RA:         61.697d {+04h 06m 47s} (J2000)
POINT_DEC:        -2.610d {-02d 36' 34"} (J2000)
POINT_ROLL:      118.317d
IMG_START_DATE:  18053 TJD;   300 DOY;   17/10/27
IMG_START_TIME:  31049.98 SOD {08:37:29.98} UT,   863.4 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        0.767
N_STARS:         51
X_OFFSET:        285 [pixels]
Y_OFFSET:        404 [pixels]
X_MAX:           1724 [pixels]
Y_MAX:           1843 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    3
SL_URL:          sw00783479000msufc0863.fits
SUN_POSTN:       211.87d {+14h 07m 29s}  -12.89d {-12d 53' 30"}
SUN_DIST:        146.40 [deg]   Sun_angle= 10.0 [hr] (West of Sun)
MOON_POSTN:      299.60d {+19h 58m 24s}  -18.65d {-18d 39' 13"}
MOON_DIST:       119.46 [deg]
MOON_ILLUM:      45 [%]
GAL_COORDS:      193.91,-37.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       59.02,-23.06 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 27 Oct 17 08:42:28 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     783479,   Seg_Num: 0
GRB_RA:           61.6908d {+04h 06m 45.79s} (J2000),
                  61.9152d {+04h 07m 39.63s} (current),
                  61.0618d {+04h 04m 14.82s} (1950)
GRB_DEC:          -2.6223d {-02d 37' 20.2"} (J2000),
                  -2.5754d {-02d 34' 31.5"} (current),
                  -2.7557d {-02d 45' 20.4"} (1950)
GRB_ERROR:       2.1 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  18053 TJD;   300 DOY;   17/10/27
IMG_START_TIME:  30489.00 SOD {08:28:09.00} UT,   302.4 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       211.87d {+14h 07m 29s}  -12.89d {-12d 53' 30"}
SUN_DIST:        146.40 [deg]   Sun_angle= 10.0 [hr] (West of Sun)
MOON_POSTN:      299.60d {+19h 58m 25s}  -18.65d {-18d 39' 11"}
MOON_DIST:       119.44 [deg]
MOON_ILLUM:      45 [%]
GAL_COORDS:      193.92,-37.31 [deg] galactic lon,lat of the burst
ECL_COORDS:       59.01,-23.07 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        This is an Update Notice -- the RA,Dec values herein supersede the previous XRT_POS Notice.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        This position was enhanced using UVOT field astrometry.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.58% < P(seren) < 1.1%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 27 Oct 17 08:42:18 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     783479,   Seg_Num: 0
POINT_RA:         61.697d {+04h 06m 47s} (J2000)
POINT_DEC:        -2.610d {-02d 36' 34"} (J2000)
POINT_ROLL:      118.317d
IMG_START_DATE:  18053 TJD;   300 DOY;   17/10/27
IMG_START_TIME:  31049.98 SOD {08:37:29.98} UT,   863.4 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        0.767
N_STARS:         51
X_OFFSET:        285 [pixels]
Y_OFFSET:        404 [pixels]
X_MAX:           1724 [pixels]
Y_MAX:           1843 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    3
SL_URL:          sw00783479000msufc0863.fits
SUN_POSTN:       211.87d {+14h 07m 29s}  -12.89d {-12d 53' 30"}
SUN_DIST:        146.40 [deg]   Sun_angle= 10.0 [hr] (West of Sun)
MOON_POSTN:      299.60d {+19h 58m 25s}  -18.65d {-18d 39' 12"}
MOON_DIST:       119.45 [deg]
MOON_ILLUM:      45 [%]
GAL_COORDS:      193.91,-37.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       59.02,-23.06 [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:     Fri 27 Oct 17 08:43:10 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     783479,   Seg_Num: 0
POINT_RA:         61.697d {+04h 06m 47s} (J2000)
POINT_DEC:        -2.610d {-02d 36' 34"} (J2000)
ROLL:            118.317d
IMG_START_DATE:  18053 TJD;   300 DOY;   17/10/27
IMG_START_TIME:  31049.98 SOD {08:37:29.98} UT,   863.4 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     530786269
X_OFFSET:        844 [pixels]
Y_OFFSET:        963 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1004
Y_GRB_POS:       1123
BINNING_INDEX:   1
IM_URL:          sw00783479000msuni0883.fits
SUN_POSTN:       211.87d {+14h 07m 29s}  -12.89d {-12d 53' 31"}
SUN_DIST:        146.40 [deg]   Sun_angle= 10.0 [hr] (West of Sun)
MOON_POSTN:      299.61d {+19h 58m 26s}  -18.65d {-18d 39' 09"}
MOON_DIST:       119.45 [deg]
MOON_ILLUM:      45 [%]
GAL_COORDS:      193.91,-37.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       59.02,-23.06 [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:     Fri 27 Oct 17 08:43:25 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     783479,   Seg_Num: 0
POINT_RA:         61.697d {+04h 06m 47s} (J2000)
POINT_DEC:        -2.610d {-02d 36' 34"} (J2000)
ROLL:            118.317d
IMG_START_DATE:  18053 TJD;   300 DOY;   17/10/27
IMG_START_TIME:  31049.98 SOD {08:37:29.98} UT,   863.4 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     530786269
X_OFFSET:        844 [pixels]
Y_OFFSET:        963 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1004
Y_GRB_POS:       1123
BINNING_INDEX:   1
IM_URL:          sw00783479000msuni0883.fits
SUN_POSTN:       211.87d {+14h 07m 29s}  -12.89d {-12d 53' 31"}
SUN_DIST:        146.40 [deg]   Sun_angle= 10.0 [hr] (West of Sun)
MOON_POSTN:      299.61d {+19h 58m 27s}  -18.65d {-18d 39' 08"}
MOON_DIST:       119.45 [deg]
MOON_ILLUM:      45 [%]
GAL_COORDS:      193.91,-37.30 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       59.02,-23.06 [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 #22054
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Using promptly downlinked XRT event data for GRB 171027A, we find an enhanced XRT position of the afterglow: RA, Dec: 61.6907, -2.6223 which is equivalent to:
```
   RA (J2000)  = 04 06 45.78
   Dec (J2000) = -02 37 20.4
```
with an uncertainty of 2.1 arcseconds (radius, 90% confidence). Analysis of the promptly available data is online at http://www.swift.ac.uk/sper/783479.
Position enhancement is is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177).
This circular is an official product of the Swift-XRT team.
GCN Circular #22055
V. Lipunov, E. Gorbovskoy, N.Tyurina, V.Kornilov, D.Kuvshinov, P.Balanutsa, A.Kuznetsov, V.V.Chazov, D. Vlasenko, I.Gorbunov, A.V.Krylov Lomonosov Moscow State University, Sternberg Astronomical Institute, Moscow State University
R. Podesta, Carlos Lopez and F. Podesta Observatorio Astronomico Felix Aguilar (OAFA)
Hugo Levato and Carlos Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)
R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias
K. Ivanov, O. Gres, N.M. Budnev, S. Yazev, O. Chuvalaev, V. Poleshchuk Irkutsk State University
A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory
V. Yurkov, A. Gabovich, Yu. Sergienko Blagoveschensk Educational State University, Blagoveschensk
D. Buckley, S. Potter, A. Kniazev, M. Kotze South African Astronomical Observatory
MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in OAFA was pointed to the GRB171027A ( D'Avanzo et al., GCN Circ 22053 ) 26 sec after notice time and 71 sec after trigger time at 2017-10-27 08:24:17 UT. On our first (10s exposure) set we haven`t found optical transient within SWIFT error-box (ra=61.6708 dec=-2.60556 r=0.05). The 5-sigma upper limit has been about 17.5 mag . This and next 2 images are prompt optical limit because GRB duration is ~ 120 sec (D'Avanzo et al., GCN Circ 22053 )
The OT limit are:
```
   ID       UT     Exp          Type             Limit

103456  08:24:17   10      Alert (SWIFT)        17.5
103463  08:24:17   70   SumAlert (SWIFT)        19.0
103473  08:24:17  550   SumAlert (SWIFT)        20.0
103457  08:25:09   20      Alert (SWIFT)        18.1
103459  08:26:10   40	   Alert (SWIFT)	18.6
103467  08:27:34  210   SumAlert (SWIFT)        19.5
103460  08:27:34   50      Alert (SWIFT)        18.6
103461  08:29:07   70      Alert (SWIFT)        18.9
103462  08:31:00   90      Alert (SWIFT)        19.0
103472  08:33:15  450   SumAlert (SWIFT)        19.9
103464  08:33:15  120      Alert (SWIFT)        19.2
103466  08:36:00  150      Alert (SWIFT)        19.2
103468  08:39:15  180      Alert (SWIFT)        19.3
103476  08:43:00  540   SumAlert (SWIFT)        19.5
103470  08:43:00  180      Alert (SWIFT)        19.0
103471  08:46:43  180      Alert (SWIFT)        18.8
103474  08:50:25  180      Alert (SWIFT)        18.4
103477  08:54:08  180      Alert (SWIFT)        18.1
103478  08:57:53  180      Alert (SWIFT)        18.1
```
The observations made on zenit distance = 41 degrees, galaxy latitude b = -37 degree. The moon (45 % bright part) below the horizon (The altitude of the Moon is -33 degree ). Observations started at twilight. The sun altitude is -16.5 degree. The object can be observed till sunrise at 2017-10-27 09:44:50
The message may be cited.
GCN Circular #22056
P. Schady (MPE) reports:
Observations of the field of GRB 171027A (Swift trigger 783479; D'Avanzo et al., GCN #22053) were carried out simultaneously in g'r'i'z' with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla Observatory (Chile).
Observations started at 08:51 UT on 27-10-2017, 28.4 mins after the GRB trigger. They were performed during astronomical twilight, at an average seeing of 1.4" and at an average airmass of 1.4.
Using a total exposure of 4.4 min, no source is detected within the 2.1" enhanced Swift/XRT error circle (Evans et al., GCN 22054) down to the following 3 sigma upper limits (all in AB):
```
g' > 23.1
r' > 23.1
i' > 22.3
z' > 22.2
```
Given magnitudes are calibration against PanSTARRS and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.12 mag in the direction of the burst (Schlafly & Finkbeiner 2011).
I acknowledge the excellent support provided by Angela Hempel in obtaining these data.
GCN Circular #22057
Alan M. Watson (UNAM), Eleonora Troja (GSFC), 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), 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 171027A (D'Avanzo et al., GCN Circ. 22053) 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 27.35 to 2017/10 27.37 UTC (0.04 to 0.51 hours after the BAT trigger), obtaining a total of 0.36 hours exposure in the r and i bands and 0.15 hours exposure in the Z, Y, J, and H bands.
For a source within the Swift-XRT error circle, in comparison with the USNO-B1 and 2MASS catalogs, we obtain the following detections and upper limits (3-sigma):
```
  r	> 23.17
  i	> 23.12
  Z	> 20.66
  Y	> 21.09
  J	 20.95 +/- 0.26
  H	 19.12 +/- 0.06
```
These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. The source position is at RA, Dec (J2000) =3D 04:06:45.77 -02:37:18.9 (+/- 0.5 arcsec). We currently have no evidence for fading.
The very red colors suggest that this might be at high redshift or dusty.
Further observations are planned.
We thank the staff of the Observatorio Astron=F3mico Nacional in San Pedro M=E1rtir.
GCN Circular #22058
P. Schady (MPE) reports:
The upper limits reported in GCN #22056 were in fact calibrated against GROND zeropoints. The 3-sigma upper limits (AB) calibrated against PanSTARRS are in fact:
```
g' > 22.2
r' > 22.2
i' > 21.2
z' > 21.0
```
The reported magnitudes are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.12 mag in the direction of the burst (Schlafly & Finkbeiner 2011).
GCN Circular #22059
C. Guidorzi (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:
We began observing Swift GRB171027A (D'Avanzo et al. GCN 22053) on October 27, from 08:39:29 to 09:06:37 UT (16 minutes since the GRB trigger time) with one of the 1-m LCO McDonald telescopes in the SDSS gri filters. Within the enhanced Swift-XRT error circle (Evans et al. 22054) and in particular at the position of the NIR afterglow candidate (Watson et al. GCN 22057) we do not see any optical source down to the following limits in agreement with previous reports (Lipunov et al. GCN 22055; Schady et al. GCN 22056):
```
Mid Time=A0=A0=A0=A0 Exposure=A0=A0=A0=A0=A0=A0 Filter=A0=A0=A0=A0=A0=A0 =
Magnitude (AB)
(hrs)=A0=A0=A0=A0=A0=A0=A0=A0 (s)
-------------------------------------------------------
0.5=A0=A0=A0=A0=A0=A0=A0=A0=A0 5x60=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 SDSS-G=A0=
=A0=A0=A0=A0=A0=A0=A0=A0 > 19.5
0.5=A0=A0=A0=A0=A0=A0=A0=A0=A0 5x60=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 SDSS-R=A0=
=A0=A0=A0=A0=A0=A0=A0=A0 > 19.3
0.5=A0=A0=A0=A0=A0=A0=A0=A0=A0 5x60=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 SDSS-I=A0=
=A0=A0=A0=A0=A0=A0=A0=A0 > 18.8
-------------------------------------------------------
```
as calibrated against nearby USNO URAT1 objects.
GCN Circular #22060
D. Malesani (DARK/NBI), N. R. Tanvir (Univ. Leicester), P. Schady (MPE), A. de Ugarte Postigo (IAA/CSIC and DARK/NBI), K. E. Heintz (Univ. Iceland and DARK/NBI), G. Pugliese (API, Univ. Amsterdam), report on behalf of the Stargate collaboration:
We observed the field of GRB 171027A (D'Avanzo et al., GCN 22053) with the ESO Very Large Telescope (VLT) UT2 equipped with X-shooter. Observations started on 2017 Oct 27.379 UT (42.8 min after the trigger) using the acquisition camera, entirely during twilight. For this reason, only short exposures could be secured (45 s in r, 60 s in z).
Within the prompt-enhanced XRT position (Evans, GCN 22054) we find no new sources down to r > 23, z > 22.7 mag (all AB, calibrated against the Pan-STARRS catalog). Our results are consistent with the lack of optical detection by GROND (Schady, GCNs 22056, 22058), RATIR (Watson et al., GCN 22057), and LCO (Guidorzi, GCN 22059). In particular, we confirm that no object is visible at the position of the NIR candidate reported by Watson et al. (GCN 22057).
We acknowledge excellent support from the ESO staff, in particular Michael Hilker and Francisco Labrana.
GCN Circular #22061
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=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 continued to observe the field of GRB 171027A (D'Avanzo et al., et al. , GCN 22053) 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 27.35 to 2017/10 27.53 UTC (0.04 to 4.24 hours after the BAT trigger), obtaining a total of 2.82 hours exposure in the r and i bands and 1.18 hours exposure in the Z, Y, J, and H bands.
At late time, the source is only detected in the H-band, with H =3D 19.12 +/- 0.06. This magnitude is calibrated relative to 2MASS and is in the AB system, not corrected for Galactic extinction in the direction of the GRB. We measure a fade in the H-band flux in time as t^(-1.0+/-0.1).
Using all bands (see, Watson et al., GCN 22057), we find high A_V photo-z solutions nearby (z<3.85, 90% conf.) and a high-z solution which assumes A_V=3D0 (z=3D9+/-1). We note that the XRT N_H constraints (D'Avanzo et al., et al., GCN 22053) point toward the high A_V solution, although with low statistical significance.
We thank the staff of the Observatorio Astron=F3mico Nacional in San Pedro M=E1rtir.
GCN Circular #22062
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team.
Using 3587 s of XRT Photon Counting mode data and 3 UVOT images for GRB 171027A, 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 = 61.69071, -2.62207 which is equivalent to:
```
RA (J2000): 04h 06m 45.77s
Dec (J2000): -02d 37' 19.5"
```
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 #22063
S. J. LaPorte (PSU), J.A. Kennea (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), S.L. Gibson (U. Leicester), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU) and P. D'Avanzo report on behalf of the Swift-XRT team:
We have analysed 6.8 ks of XRT data for GRB 171027A (D'Avanzo et al. GCN Circ. 22053), from 81 s to 18.6 ks after the BAT trigger. The data comprise 191 s in Windowed Timing (WT) mode (the first 5 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 Goad et al. (GCN Circ. 22054).
The light curve can be modelled with an initial power-law decay with an index of alpha=3.53 (+/-0.12), followed by a break at T+274 s to an alpha of 0.96 (+/-0.03).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.43 (+/-0.07). The best-fitting absorption column is 2.8 (+/-0.4) x 10^21 cm^-2, in excess of the Galactic value of 1.1 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 2.02 (+0.13, -0.12) and a best-fitting absorption column of 3.6 (+0.6, -0.5) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.8 x 10^-11 (5.8 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     3.6 (+0.6, -0.5) x 10^21 cm^-2
Galactic foreground: 1.1 x 10^21 cm^-2
Excess significance: 7.7 sigma
Photon index:	     2.02 (+0.13, -0.12)
```
If the light curve continues to decay with a power-law decay index of 0.96, the count rate at T+24 hours will be 0.026 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 9.7 x 10^-13 (1.5 x 10^-12) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00783479.
This circular is an official product of the Swift-XRT team.
GCN Circular #22064
S. R. Oates (U. Warwick) and P. D'Avanzo (INAF-OAB) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 171027A 96 s after the BAT trigger (D'Avanzo et al., GCN Circ. 22053). No optical afterglow consistent with the optical position (Watson et al. GCN Circ. 22057) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC            96          246          147         >20.6
u_FC               308          558          246         >20.0
white               96         6148          428         >21.2
v                  639         6558          432         >19.7
b                  564         5943          236         >20.3
u                  308         5737          462         >20.3
w1                 688         6835          282         >19.8
m2                5126         6763          393         >19.8
w2                4716         6354          393         >20.1
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.14 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #22066
A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), P. D'Avanzo (INAF-OAB), H. A. Krimm (NSF/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-61 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 171027A (trigger #783479) (D'Avanzo et al., GCN Circ. 22053). The BAT ground-calculated position is RA, Dec = 61.683, -2.601 deg which is
```
  RA(J2000)  =  04h 06m 43.8s
  Dec(J2000) = -02d 36' 02.0"
```
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 91%.
The mask-weighted light curve shows a multi-peaked structure that starts at ~T-2 s and ends at ~T+150 s. The main peak occurs at ~ T+63 s. T90 (15-350 keV) is 96.6 +- 4.8 sec (estimated error including systematics).
The time-averaged spectrum from T-2.0 to T+132.0 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 1.25 +- 0.18, and Epeak of 150.4 +- 95.1 keV (chi squared 33.21 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 7.5 +- 0.2 x 10^-6 erg/cm2 and the 1-sec peak flux measured from T+62.29 sec in the 15-150 keV band is 3.0 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.53 +- 0.04 (chi squared 40.62 for 57 d.o.f.). 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/783479/BA/
GCN Circular #22070
D. Frederiks, S. Golenetskii, R.Aptekar, P. Oleynik, M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko, A. Kozlova, and T. Cline, on behalf of the Konus-Wind team, report:
The long GRB 171027A (Swift-BAT trigger #783479: (D'Avanzo et al., GCN 22053; Lien et al., GCN 22066; T0(BAT)=3D08:23:06.623 UT) was detected by Konus-Wind (KW) in the waiting mode.
The light curve shows a muli-peaked structure with a duration of ~103 s. Modeling the KW 3-channel time-integrated spectrum (from T0(BAT)-1.661 s to T0(BAT)+101.379 s) by a power law with exponential cutoff (CPL) model dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) yields alpha =3D -1.21(-0.35,+0.20) and Ep =3D 176(-35,+47) keV. The energy fluence for this time interval is (1.78 =B1 0.21)x10^-5 erg/cm2, and the peak energy flux, measured on a 2.944 s scale from T0(BAT)+63.107 s is (6.6 =B1 0.12)x10^-7 erg/cm2/s, both in the 20 keV-10 MeV range.
Assuming the GRB photo-z < 3.85 (90%, Butler et al., GCN 22061) and a standard cosmology model with H_0 =3D 70 km/s/Mpc, Omega_M =3D 0.30, and Omega_Lambda =3D 0.70, our analysis sets the following upper limits on the burst isotropic energy release and rest-frame peak energy: E_iso < 5.2x10^53 erg and Ep,z < 854 keV.
The K-W light curve of this burst is available at http://www.ioffe.rssi.ru/LEA/GRBs/GRB171027A/
All the quoted errors are estimated at the 1 sigma confidence level. All the presented results are preliminary.
GCN Circular #22073
WeiKang Zheng and Alexei V. Filippenko (UC Berkeley) report on behalf of the KAIT GRB team:
The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at Lick Observatory, responded to Swift GRB 171027A (D'Avanzo et al., GCN 22053) starting at 08:26:07 UT, 181 s after the burst. Observations were performed with an automatic sequence in the clear (roughly R), V, and I filters, and the exposure time was 20 s per image. We do not detect the optical source (Watson et al., GCN 22057; Butler et al., GCN 22061) in our images. The typical limiting magnitude of our single clear image is about 19.0 calibrated to USNO B1.0.

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Jochen Greiner, last update: 31-Oct-2017 [Disclaimer]