Gamma-ray Burst 170912A

(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 12 Sep 17 01:34:58 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     772006,   Seg_Num: 0
GRB_RA:          167.372d {+11h 09m 29s} (J2000),
                 167.569d {+11h 10m 17s} (current),
                 166.818d {+11h 07m 16s} (1950)
GRB_DEC:         -54.360d {-54d 21' 34"} (J2000),
                 -54.456d {-54d 27' 20"} (current),
                 -54.088d {-54d 05' 17"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       17620 [cnts]    Image_Peak=440 [image_cnts]
TRIGGER_DUR:     4.096 [sec] 
TRIGGER_INDEX:   291     E_range: 15-50 keV
BKG_INTEN:       155521 [cnts]
BKG_TIME:        5596.32 SOD {01:33:16.32} UT
BKG_DUR:         40 [sec]
GRB_DATE:        18008 TJD;   255 DOY;   17/09/12
GRB_TIME:        5656.93 SOD {01:34:16.93} UT
GRB_PHI:         -139.72 [deg]
GRB_THETA:        40.64 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     13.74 [sigma]
IMAGE_SIGNIF:    10.13 [sigma]
MERIT_PARAMS:     +1  +0  +0  +2  +1  +0  +0  +1 -52  +0 
SUN_POSTN:       170.34d {+11h 21m 22s}   +4.16d {+04d 09' 31"}
SUN_DIST:         58.66 [deg]   Sun_angle= 0.2 [hr] (West of Sun)
MOON_POSTN:       62.58d {+04h 10m 19s}  +15.79d {+15d 47' 13"}
MOON_DIST:       111.47 [deg]
MOON_ILLUM:      64 [%]
GAL_COORDS:      288.34,  5.60 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      199.95,-52.78 [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 = 142.18,-20.45 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 12 Sep 17 01:36:25 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     772006,   Seg_Num: 0
POINT_RA:        167.384d {+11h 09m 32s} (J2000)
POINT_DEC:       -54.377d {-54d 22' 38"} (J2000)
IMG_START_DATE:  18008 TJD;   255 DOY;   17/09/12
IMG_START_TIME:  5775.64 SOD {01:36:15.64} UT,   118.7 [sec] since BAT Trigger Time
COUNTS:          17    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        1    Max_iter_allowed= 4
ERROR_CODE:      1
COMMENTS:        SWIFT-XRT Nack Position.  
COMMENTS:        No source found in the image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 12 Sep 17 01:37:50 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     772006,   Seg_Num: 0
GRB_RA:          167.372d {+11h 09m 29s} (J2000),
                 167.569d {+11h 10m 17s} (current),
                 166.818d {+11h 07m 16s} (1950)
GRB_DEC:         -54.360d {-54d 21' 34"} (J2000),
                 -54.456d {-54d 27' 20"} (current),
                 -54.088d {-54d 05' 17"} (1950)
GRB_DATE:        18008 TJD;   255 DOY;   17/09/12
GRB_TIME:        5656.93 SOD {01:34:16.93} UT
TRIGGER_INDEX:   291
GRB_PHI:         -139.72 [deg]
GRB_THETA:        40.64 [deg]
DELTA_TIME:      19.00 [sec]
TRIGGER_DUR:     4.096 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     13.74 [sigma]
IMAGE_SIGNIF:    10.13 [sigma]
LC_URL:          sw00772006000msb.lc
SUN_POSTN:       170.35d {+11h 21m 23s}   +4.16d {+04d 09' 28"}
SUN_DIST:         58.66 [deg]   Sun_angle= 0.2 [hr] (West of Sun)
MOON_POSTN:       62.61d {+04h 10m 26s}  +15.79d {+15d 47' 33"}
MOON_DIST:       111.46 [deg]
MOON_ILLUM:      64 [%]
GAL_COORDS:      288.34,  5.60 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      199.95,-52.78 [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 = 142.18,-20.45 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 12 Sep 17 01:40:09 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     772006,   Seg_Num: 0
POINT_RA:        167.384d {+11h 09m 32s} (J2000)
POINT_DEC:       -54.377d {-54d 22' 38"} (J2000)
POINT_ROLL:      3.467d
IMG_START_DATE:  18008 TJD;   255 DOY;   17/09/12
IMG_START_TIME:  5779.10 SOD {01:36:19.10} UT,   122.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.194
N_STARS:         190
X_OFFSET:        560 [pixels]
Y_OFFSET:        426 [pixels]
X_MAX:           1519 [pixels]
Y_MAX:           1385 [pixels]
DET_THRESH:      17
PHOTO_THRESH:    10
SL_URL:          sw00772006000msufc0122.fits
SUN_POSTN:       170.35d {+11h 21m 23s}   +4.16d {+04d 09' 26"}
SUN_DIST:         58.68 [deg]   Sun_angle= 0.2 [hr] (West of Sun)
MOON_POSTN:       62.63d {+04h 10m 32s}  +15.80d {+15d 47' 49"}
MOON_DIST:       111.46 [deg]
MOON_ILLUM:      64 [%]
GAL_COORDS:      288.35,  5.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      199.98,-52.79 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 12 Sep 17 01:40:15 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     772006,   Seg_Num: 0
GRB_RA:          167.3734d {+11h 09m 29.61s} (J2000),
                 167.5703d {+11h 10m 16.87s} (current),
                 166.8191d {+11h 07m 16.57s} (1950)
GRB_DEC:         -54.3269d {-54d 19' 36.8"} (J2000),
                 -54.4231d {-54d 25' 23.0"} (current),
                 -54.0555d {-54d 03' 19.8"} (1950)
GRB_ERROR:       3.9 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  18008 TJD;   255 DOY;   17/09/12
IMG_START_TIME:  5813.00 SOD {01:36:53.00} UT,   156.1 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       170.35d {+11h 21m 23s}   +4.16d {+04d 09' 25"}
SUN_DIST:         58.63 [deg]   Sun_angle= 0.2 [hr] (West of Sun)
MOON_POSTN:       62.63d {+04h 10m 32s}  +15.80d {+15d 47' 50"}
MOON_DIST:       111.45 [deg]
MOON_ILLUM:      64 [%]
GAL_COORDS:      288.33,  5.63 [deg] galactic lon,lat of the burst
ECL_COORDS:      199.92,-52.75 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.58% < P(seren) < 1.1%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 12 Sep 17 01:40:36 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     772006,   Seg_Num: 0
POINT_RA:        167.384d {+11h 09m 32s} (J2000)
POINT_DEC:       -54.377d {-54d 22' 38"} (J2000)
POINT_ROLL:      3.467d
IMG_START_DATE:  18008 TJD;   255 DOY;   17/09/12
IMG_START_TIME:  5779.10 SOD {01:36:19.10} UT,   122.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.194
N_STARS:         190
X_OFFSET:        560 [pixels]
Y_OFFSET:        426 [pixels]
X_MAX:           1519 [pixels]
Y_MAX:           1385 [pixels]
DET_THRESH:      17
PHOTO_THRESH:    10
SL_URL:          sw00772006000msufc0122.fits
SUN_POSTN:       170.35d {+11h 21m 23s}   +4.16d {+04d 09' 25"}
SUN_DIST:         58.68 [deg]   Sun_angle= 0.2 [hr] (West of Sun)
MOON_POSTN:       62.64d {+04h 10m 33s}  +15.80d {+15d 47' 52"}
MOON_DIST:       111.45 [deg]
MOON_ILLUM:      64 [%]
GAL_COORDS:      288.35,  5.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      199.98,-52.79 [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 12 Sep 17 01:42:11 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     772006,   Seg_Num: 0
POINT_RA:        167.384d {+11h 09m 32s} (J2000)
POINT_DEC:       -54.377d {-54d 22' 38"} (J2000)
ROLL:            3.467d
IMG_START_DATE:  18008 TJD;   255 DOY;   17/09/12
IMG_START_TIME:  5779.10 SOD {01:36:19.10} UT,   122.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     526872998
X_OFFSET:        879 [pixels]
Y_OFFSET:        745 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1039
Y_GRB_POS:       905
BINNING_INDEX:   1
IM_URL:          sw00772006000msuni0142.fits
SUN_POSTN:       170.35d {+11h 21m 23s}   +4.16d {+04d 09' 24"}
SUN_DIST:         58.68 [deg]   Sun_angle= 0.2 [hr] (West of Sun)
MOON_POSTN:       62.65d {+04h 10m 37s}  +15.80d {+15d 48' 03"}
MOON_DIST:       111.45 [deg]
MOON_ILLUM:      64 [%]
GAL_COORDS:      288.35,  5.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      199.98,-52.79 [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:     Tue 12 Sep 17 01:42:18 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     772006,   Seg_Num: 0
POINT_RA:        167.384d {+11h 09m 32s} (J2000)
POINT_DEC:       -54.377d {-54d 22' 38"} (J2000)
ROLL:            3.467d
IMG_START_DATE:  18008 TJD;   255 DOY;   17/09/12
IMG_START_TIME:  5779.10 SOD {01:36:19.10} UT,   122.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     526872998
X_OFFSET:        879 [pixels]
Y_OFFSET:        745 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1039
Y_GRB_POS:       905
BINNING_INDEX:   1
IM_URL:          sw00772006000msuni0142.fits
SUN_POSTN:       170.35d {+11h 21m 23s}   +4.16d {+04d 09' 24"}
SUN_DIST:         58.68 [deg]   Sun_angle= 0.2 [hr] (West of Sun)
MOON_POSTN:       62.65d {+04h 10m 37s}  +15.80d {+15d 48' 04"}
MOON_DIST:       111.45 [deg]
MOON_ILLUM:      64 [%]
GAL_COORDS:      288.35,  5.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      199.98,-52.79 [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 #21861
A. Tohuvavohu (PSU), D. N. Burrows (PSU), C. Gronwall (PSU), A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL), B. Sbarufatti (PSU) and M. H. Siegel (PSU) report on behalf of the Swift Team:
At 01:34:16 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 170912A (trigger=772006). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 167.372, -54.360 which is
```
   RA(J2000) = 11h 09m 29s
   Dec(J2000) = -54d 21' 34"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single-peak structure with a duration of about 20 sec. The peak count rate was ~1200 counts/sec (15-350 keV), at ~1 sec after the trigger.
The XRT began observing the field at 01:36:15.6 UT, 118.7 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source located at RA, Dec 167.37341, -54.32690 which is equivalent to:
```
   RA(J2000)  = 11h 09m 29.62s
   Dec(J2000) = -54d 19' 36.8"
```
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This location is 119 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper.
A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 3.14 x 10^21 cm^-2 (Willingale et al. 2013).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 122 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 none of the XRT error circle. 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 0.46.
Burst Advocate for this burst is A. Tohuvavohu (aaronb AT swift.psu.edu). 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:     Tue 12 Sep 17 01:49:15 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     772006,   Seg_Num: 0
POINT_RA:        167.387d {+11h 09m 33s} (J2000)
POINT_DEC:       -54.379d {-54d 22' 43"} (J2000)
POINT_ROLL:      3.463d
IMG_START_DATE:  18008 TJD;   255 DOY;   17/09/12
IMG_START_TIME:  5992.35 SOD {01:39:52.35} UT,   335.4 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.521
N_STARS:         190
X_OFFSET:        320 [pixels]
Y_OFFSET:        186 [pixels]
X_MAX:           1759 [pixels]
Y_MAX:           1625 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00772006000msufc0335.fits
SUN_POSTN:       170.35d {+11h 21m 25s}   +4.15d {+04d 09' 17"}
SUN_DIST:         58.68 [deg]   Sun_angle= 0.2 [hr] (West of Sun)
MOON_POSTN:       62.72d {+04h 10m 54s}  +15.81d {+15d 48' 53"}
MOON_DIST:       111.42 [deg]
MOON_ILLUM:      64 [%]
GAL_COORDS:      288.36,  5.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      199.98,-52.79 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 12 Sep 17 01:49:29 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     772006,   Seg_Num: 0
POINT_RA:        167.387d {+11h 09m 33s} (J2000)
POINT_DEC:       -54.379d {-54d 22' 43"} (J2000)
POINT_ROLL:      3.463d
IMG_START_DATE:  18008 TJD;   255 DOY;   17/09/12
IMG_START_TIME:  5992.35 SOD {01:39:52.35} UT,   335.4 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.521
N_STARS:         190
X_OFFSET:        320 [pixels]
Y_OFFSET:        186 [pixels]
X_MAX:           1759 [pixels]
Y_MAX:           1625 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00772006000msufc0335.fits
SUN_POSTN:       170.35d {+11h 21m 25s}   +4.15d {+04d 09' 17"}
SUN_DIST:         58.68 [deg]   Sun_angle= 0.2 [hr] (West of Sun)
MOON_POSTN:       62.73d {+04h 10m 54s}  +15.82d {+15d 48' 54"}
MOON_DIST:       111.42 [deg]
MOON_ILLUM:      64 [%]
GAL_COORDS:      288.36,  5.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      199.98,-52.79 [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 12 Sep 17 01:49:49 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     772006,   Seg_Num: 0
GRB_RA:          167.3730d {+11h 09m 29.51s} (J2000),
                 167.5699d {+11h 10m 16.78s} (current),
                 166.8187d {+11h 07m 16.47s} (1950)
GRB_DEC:         -54.3265d {-54d 19' 35.4"} (J2000),
                 -54.4227d {-54d 25' 21.6"} (current),
                 -54.0551d {-54d 03' 18.4"} (1950)
GRB_ERROR:       2.4 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  18008 TJD;   255 DOY;   17/09/12
IMG_START_TIME:  5813.00 SOD {01:36:53.00} UT,   156.1 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       170.35d {+11h 21m 25s}   +4.15d {+04d 09' 16"}
SUN_DIST:         58.62 [deg]   Sun_angle= 0.2 [hr] (West of Sun)
MOON_POSTN:       62.73d {+04h 10m 55s}  +15.82d {+15d 48' 57"}
MOON_DIST:       111.41 [deg]
MOON_ILLUM:      64 [%]
GAL_COORDS:      288.33,  5.63 [deg] galactic lon,lat of the burst
ECL_COORDS:      199.92,-52.75 [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:     Tue 12 Sep 17 01:50:44 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     772006,   Seg_Num: 0
POINT_RA:        167.387d {+11h 09m 33s} (J2000)
POINT_DEC:       -54.379d {-54d 22' 43"} (J2000)
ROLL:            3.463d
IMG_START_DATE:  18008 TJD;   255 DOY;   17/09/12
IMG_START_TIME:  5992.35 SOD {01:39:52.35} UT,   335.4 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     526873212
X_OFFSET:        879 [pixels]
Y_OFFSET:        745 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1039
Y_GRB_POS:       905
BINNING_INDEX:   1
IM_URL:          sw00772006000msuni0355.fits
SUN_POSTN:       170.35d {+11h 21m 25s}   +4.15d {+04d 09' 15"}
SUN_DIST:         58.67 [deg]   Sun_angle= 0.2 [hr] (West of Sun)
MOON_POSTN:       62.74d {+04h 10m 57s}  +15.82d {+15d 49' 03"}
MOON_DIST:       111.41 [deg]
MOON_ILLUM:      64 [%]
GAL_COORDS:      288.36,  5.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      199.98,-52.79 [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:     Tue 12 Sep 17 01:50:58 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     772006,   Seg_Num: 0
POINT_RA:        167.387d {+11h 09m 33s} (J2000)
POINT_DEC:       -54.379d {-54d 22' 43"} (J2000)
ROLL:            3.463d
IMG_START_DATE:  18008 TJD;   255 DOY;   17/09/12
IMG_START_TIME:  5992.35 SOD {01:39:52.35} UT,   335.4 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     526873212
X_OFFSET:        879 [pixels]
Y_OFFSET:        745 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1039
Y_GRB_POS:       905
BINNING_INDEX:   1
IM_URL:          sw00772006000msuni0355.fits
SUN_POSTN:       170.35d {+11h 21m 25s}   +4.15d {+04d 09' 15"}
SUN_DIST:         58.67 [deg]   Sun_angle= 0.2 [hr] (West of Sun)
MOON_POSTN:       62.74d {+04h 10m 58s}  +15.82d {+15d 49' 05"}
MOON_DIST:       111.41 [deg]
MOON_ILLUM:      64 [%]
GAL_COORDS:      288.36,  5.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      199.98,-52.79 [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 NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 12 Sep 17 01:56:15 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     772006,   Seg_Num: 0
POINT_RA:        167.387d {+11h 09m 33s} (J2000)
POINT_DEC:       -54.379d {-54d 22' 43"} (J2000)
POINT_ROLL:      3.463d
IMG_START_DATE:  18008 TJD;   255 DOY;   17/09/12
IMG_START_TIME:  6522.55 SOD {01:48:42.55} UT,   865.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        5.574
N_STARS:         190
X_OFFSET:        320 [pixels]
Y_OFFSET:        186 [pixels]
X_MAX:           1759 [pixels]
Y_MAX:           1625 [pixels]
DET_THRESH:      20
PHOTO_THRESH:    12
SL_URL:          sw00772006000msufc0865.fits
SUN_POSTN:       170.36d {+11h 21m 26s}   +4.15d {+04d 09' 10"}
SUN_DIST:         58.67 [deg]   Sun_angle= 0.2 [hr] (West of Sun)
MOON_POSTN:       62.79d {+04h 11m 10s}  +15.83d {+15d 49' 42"}
MOON_DIST:       111.39 [deg]
MOON_ILLUM:      64 [%]
GAL_COORDS:      288.36,  5.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      199.98,-52.79 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 12 Sep 17 01:56:35 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     772006,   Seg_Num: 0
POINT_RA:        167.387d {+11h 09m 33s} (J2000)
POINT_DEC:       -54.379d {-54d 22' 43"} (J2000)
POINT_ROLL:      3.463d
IMG_START_DATE:  18008 TJD;   255 DOY;   17/09/12
IMG_START_TIME:  6522.55 SOD {01:48:42.55} UT,   865.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        5.574
N_STARS:         190
X_OFFSET:        320 [pixels]
Y_OFFSET:        186 [pixels]
X_MAX:           1759 [pixels]
Y_MAX:           1625 [pixels]
DET_THRESH:      20
PHOTO_THRESH:    12
SL_URL:          sw00772006000msufc0865.fits
SUN_POSTN:       170.36d {+11h 21m 26s}   +4.15d {+04d 09' 10"}
SUN_DIST:         58.67 [deg]   Sun_angle= 0.2 [hr] (West of Sun)
MOON_POSTN:       62.80d {+04h 11m 11s}  +15.83d {+15d 49' 44"}
MOON_DIST:       111.39 [deg]
MOON_ILLUM:      64 [%]
GAL_COORDS:      288.36,  5.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      199.98,-52.79 [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 12 Sep 17 01:58:59 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     772006,   Seg_Num: 0
POINT_RA:        167.387d {+11h 09m 33s} (J2000)
POINT_DEC:       -54.379d {-54d 22' 43"} (J2000)
ROLL:            3.463d
IMG_START_DATE:  18008 TJD;   255 DOY;   17/09/12
IMG_START_TIME:  6522.55 SOD {01:48:42.55} UT,   865.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     526873742
X_OFFSET:        879 [pixels]
Y_OFFSET:        745 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1039
Y_GRB_POS:       905
BINNING_INDEX:   1
IM_URL:          sw00772006000msuni0885.fits
SUN_POSTN:       170.36d {+11h 21m 26s}   +4.15d {+04d 09' 08"}
SUN_DIST:         58.67 [deg]   Sun_angle= 0.2 [hr] (West of Sun)
MOON_POSTN:       62.82d {+04h 11m 17s}  +15.83d {+15d 50' 01"}
MOON_DIST:       111.38 [deg]
MOON_ILLUM:      64 [%]
GAL_COORDS:      288.36,  5.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      199.98,-52.79 [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:     Tue 12 Sep 17 01:59:07 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     772006,   Seg_Num: 0
POINT_RA:        167.387d {+11h 09m 33s} (J2000)
POINT_DEC:       -54.379d {-54d 22' 43"} (J2000)
ROLL:            3.463d
IMG_START_DATE:  18008 TJD;   255 DOY;   17/09/12
IMG_START_TIME:  6522.55 SOD {01:48:42.55} UT,   865.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     526873742
X_OFFSET:        879 [pixels]
Y_OFFSET:        745 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1039
Y_GRB_POS:       905
BINNING_INDEX:   1
IM_URL:          sw00772006000msuni0885.fits
SUN_POSTN:       170.36d {+11h 21m 26s}   +4.15d {+04d 09' 07"}
SUN_DIST:         58.67 [deg]   Sun_angle= 0.2 [hr] (West of Sun)
MOON_POSTN:       62.82d {+04h 11m 17s}  +15.83d {+15d 50' 02"}
MOON_DIST:       111.38 [deg]
MOON_ILLUM:      64 [%]
GAL_COORDS:      288.36,  5.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      199.98,-52.79 [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 #21862
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Using promptly downlinked XRT event data for GRB 170912A, we find an enhanced XRT position of the afterglow: RA, Dec: 167.3734, -54.3262 which is equivalent to:
```
   RA (J2000)  = 11 09 29.61
   Dec (J2000) = -54 19 34.4
```
with an uncertainty of 2.2 arcseconds (radius, 90% confidence). Analysis of the promptly available data is online at http://www.swift.ac.uk/sper/772006.
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 #21863
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team.
Using 426 s of XRT Photon Counting mode data and 1 UVOT images for GRB 170912A, 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 = 167.37343, -54.32638 which is equivalent to:
```
RA (J2000): 11h 09m 29.62s
Dec (J2000): -54d 19' 35.0"
```
with an uncertainty of 2.1 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 #21874
GRB 170912A: Swift/UVOT Upper Limits
S. J. LaPorte (PSU) and Tohuvavohu (PSU) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 170912A 122 s after the BAT trigger (Tohuvavohu et al., GCN Circ. 21861). No optical afterglow consistent with the XRT position (Goad et al. GCN Circ. 21863) 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           122          272          147         >20.9
u_FC               335          585          246         >19.4
white              122         1362          373         >21.6
v                  666         1412           97         >18.8
b                  591         1338           78         >19.6
u                  335         1313          304         >19.2
w1                 715         1461           78         >18.7
m2                 690         1436           78         >20.0
w2                 641         1387           97         >19.7
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.46 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #21876
J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), P.A. Evans (U. Leicester), S.L. Gibson (U. Leicester), J.P. Osborne (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), D.N. Burrows (PSU) and A. Tohuvavohu report on behalf of the Swift-XRT team:
We have analysed 6.5 ks of XRT data for GRB 170912A (Tohuvavohu et al. GCN Circ. 21861), from 104 s to 62.2 ks after the BAT trigger. The data comprise 17 s in Windowed Timing (WT) mode (the first 8 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. 21862).
The light curve can be modelled with a power-law decay with a decay index of alpha=4.8 (+nan, -nan).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.85 (+0.54, -0.22). The best-fitting absorption column is consistent with the Galactic value of 3.1 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.9 x 10^-11 (5.4 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     3.1 (+/-2.3) x 10^21 cm^-2
Galactic foreground: 3.1 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.85 (+0.54, -0.22)
```
If the light curve continues to decay with a power-law decay index of 4.8, the count rate at T+24 hours will be 1.4 x 10^-13 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.4 x 10^-24 (7.4 x 10^-24) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00772006.
This circular is an official product of the Swift-XRT team.
GCN Circular #21877
C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), A. Tohuvavohu (PSU), 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 170912A (trigger #772006) (Tohuvavohu et al., GCN Circ. 21861). The BAT ground-calculated position is RA, Dec = 167.386, -54.343 deg which is
```
  RA(J2000)  =  11h 09m 32.6s
  Dec(J2000) = -54d 20' 35.4"
```
with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 34%.
The mask-weighted light curve shows a single-peaked structure that starts at ~T0, peaks at ~T+3, and ends at ~T+25 s. T90 (15-350 keV) is 21.9 +- 5.6 sec (estimated error including systematics).
The time-averaged spectrum from T-0.42 to T+25.64 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.04 +- 0.21. The fluence in the 15-150 keV band is 1.1 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+2.38 sec in the 15-150 keV band is 2.0 +- 0.4 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/772006/BA/

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Jochen Greiner, last update: 12-Sep-2017 [Disclaimer]