Gamma-ray Burst 140927A

(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:     Sat 27 Sep 14 05:16:06 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     613775,   Seg_Num: 0
GRB_RA:          291.845d {+19h 27m 23s} (J2000),
                 292.199d {+19h 28m 48s} (current),
                 290.636d {+19h 22m 33s} (1950)
GRB_DEC:         -65.388d {-65d 23' 14"} (J2000),
                 -65.357d {-65d 21' 23"} (current),
                 -65.488d {-65d 29' 17"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       27969 [cnts]    Image_Peak=413 [image_cnts]
TRIGGER_DUR:     8.192 [sec] 
TRIGGER_INDEX:   477     E_range: 25-100 keV
BKG_INTEN:       203399 [cnts]
BKG_TIME:        18819.42 SOD {05:13:39.42} UT
BKG_DUR:         64 [sec]
GRB_DATE:        16927 TJD;   270 DOY;   14/09/27
GRB_TIME:        18911.38 SOD {05:15:11.38} UT
GRB_PHI:         169.23 [deg]
GRB_THETA:        36.60 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     9.11 [sigma]
IMAGE_SIGNIF:    7.16 [sigma]
MERIT_PARAMS:     +1  +0  +0  +3  +2  -3  +0  +0 +10  +0 
SUN_POSTN:       183.70d {+12h 14m 48s}   -1.60d {-01d 36' 04"}
SUN_DIST:         96.13 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      216.09d {+14h 24m 22s}  -12.59d {-12d 35' 25"}
MOON_DIST:        72.79 [deg]
MOON_ILLUM:      9 [%]
GAL_COORDS:      330.75,-28.19 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      282.21,-42.87 [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 = 161.33,6.39 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 27 Sep 14 05:17:21 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     613775,   Seg_Num: 0
POINT_RA:        291.879d {+19h 27m 31s} (J2000)
POINT_DEC:       -65.377d {-65d 22' 35"} (J2000)
IMG_START_DATE:  16927 TJD;   270 DOY;   14/09/27
IMG_START_TIME:  19033.73 SOD {05:17:13.73} UT,   122.3 [sec] since BAT Trigger Time
COUNTS:          10    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        3    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:     Sat 27 Sep 14 05:18:50 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     613775,   Seg_Num: 0
GRB_RA:          291.845d {+19h 27m 23s} (J2000),
                 292.199d {+19h 28m 48s} (current),
                 290.636d {+19h 22m 33s} (1950)
GRB_DEC:         -65.388d {-65d 23' 14"} (J2000),
                 -65.357d {-65d 21' 23"} (current),
                 -65.488d {-65d 29' 17"} (1950)
GRB_DATE:        16927 TJD;   270 DOY;   14/09/27
GRB_TIME:        18911.38 SOD {05:15:11.38} UT
TRIGGER_INDEX:   477
GRB_PHI:         169.23 [deg]
GRB_THETA:        36.60 [deg]
DELTA_TIME:      -75.00 [sec]
TRIGGER_DUR:     8.192 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     9.11 [sigma]
IMAGE_SIGNIF:    7.16 [sigma]
LC_URL:          sw00613775000msb.lc
SUN_POSTN:       183.70d {+12h 14m 48s}   -1.60d {-01d 36' 06"}
SUN_DIST:         96.13 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      216.12d {+14h 24m 28s}  -12.60d {-12d 35' 46"}
MOON_DIST:        72.78 [deg]
MOON_ILLUM:      9 [%]
GAL_COORDS:      330.75,-28.19 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      282.21,-42.87 [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 = 161.33,6.39 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 27 Sep 14 05:21:27 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     613775,   Seg_Num: 0
GRB_RA:          291.7924d {+19h 27m 10.17s} (J2000),
                 292.1472d {+19h 28m 35.33s} (current),
                 290.5838d {+19h 22m 20.10s} (1950)
GRB_DEC:         -65.3926d {-65d 23' 33.3"} (J2000),
                 -65.3619d {-65d 21' 42.8"} (current),
                 -65.4932d {-65d 29' 35.6"} (1950)
GRB_ERROR:       3.8 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  16927 TJD;   270 DOY;   14/09/27
IMG_START_TIME:  19051.00 SOD {05:17:31.00} UT,   139.6 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       183.70d {+12h 14m 48s}   -1.60d {-01d 36' 09"}
SUN_DIST:         96.11 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      216.14d {+14h 24m 33s}  -12.60d {-12d 36' 05"}
MOON_DIST:        72.74 [deg]
MOON_ILLUM:      9 [%]
GAL_COORDS:      330.75,-28.17 [deg] galactic lon,lat of the burst
ECL_COORDS:      282.18,-42.87 [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:     Sat 27 Sep 14 05:22:06 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     613775,   Seg_Num: 0
POINT_RA:        291.879d {+19h 27m 31s} (J2000)
POINT_DEC:       -65.377d {-65d 22' 35"} (J2000)
POINT_ROLL:      252.714d
IMG_START_DATE:  16927 TJD;   270 DOY;   14/09/27
IMG_START_TIME:  19034.43 SOD {05:17:14.43} UT,   123.0 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.619
N_STARS:         190
X_OFFSET:        310 [pixels]
Y_OFFSET:        207 [pixels]
X_MAX:           1749 [pixels]
Y_MAX:           1646 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw00613775000msufc0123.fits
SUN_POSTN:       183.70d {+12h 14m 48s}   -1.60d {-01d 36' 10"}
SUN_DIST:         96.15 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      216.14d {+14h 24m 35s}  -12.60d {-12d 36' 10"}
MOON_DIST:        72.77 [deg]
MOON_ILLUM:      9 [%]
GAL_COORDS:      330.77,-28.21 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      282.23,-42.86 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 27 Sep 14 05:22:42 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     613775,   Seg_Num: 0
POINT_RA:        291.879d {+19h 27m 31s} (J2000)
POINT_DEC:       -65.377d {-65d 22' 35"} (J2000)
POINT_ROLL:      252.714d
IMG_START_DATE:  16927 TJD;   270 DOY;   14/09/27
IMG_START_TIME:  19034.43 SOD {05:17:14.43} UT,   123.0 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.619
N_STARS:         190
X_OFFSET:        310 [pixels]
Y_OFFSET:        207 [pixels]
X_MAX:           1749 [pixels]
Y_MAX:           1646 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw00613775000msufc0123.fits
SUN_POSTN:       183.70d {+12h 14m 49s}   -1.60d {-01d 36' 10"}
SUN_DIST:         96.15 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      216.15d {+14h 24m 36s}  -12.60d {-12d 36' 15"}
MOON_DIST:        72.77 [deg]
MOON_ILLUM:      9 [%]
GAL_COORDS:      330.77,-28.21 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      282.23,-42.86 [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:     Sat 27 Sep 14 05:23:27 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     613775,   Seg_Num: 0
POINT_RA:        291.879d {+19h 27m 31s} (J2000)
POINT_DEC:       -65.377d {-65d 22' 35"} (J2000)
ROLL:            252.714d
IMG_START_DATE:  16927 TJD;   270 DOY;   14/09/27
IMG_START_TIME:  19034.43 SOD {05:17:14.43} UT,   123.0 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     433487847
X_OFFSET:        869 [pixels]
Y_OFFSET:        766 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1029
Y_GRB_POS:       926
BINNING_INDEX:   1
IM_URL:          sw00613775000msuni0136.fits
SUN_POSTN:       183.70d {+12h 14m 49s}   -1.60d {-01d 36' 11"}
SUN_DIST:         96.15 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      216.16d {+14h 24m 38s}  -12.61d {-12d 36' 20"}
MOON_DIST:        72.76 [deg]
MOON_ILLUM:      9 [%]
GAL_COORDS:      330.77,-28.21 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      282.23,-42.86 [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:     Sat 27 Sep 14 05:23:46 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     613775,   Seg_Num: 0
POINT_RA:        291.879d {+19h 27m 31s} (J2000)
POINT_DEC:       -65.377d {-65d 22' 35"} (J2000)
ROLL:            252.714d
IMG_START_DATE:  16927 TJD;   270 DOY;   14/09/27
IMG_START_TIME:  19034.43 SOD {05:17:14.43} UT,   123.0 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     433487847
X_OFFSET:        869 [pixels]
Y_OFFSET:        766 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1029
Y_GRB_POS:       926
BINNING_INDEX:   1
IM_URL:          sw00613775000msuni0136.fits
SUN_POSTN:       183.70d {+12h 14m 49s}   -1.60d {-01d 36' 11"}
SUN_DIST:         96.15 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      216.16d {+14h 24m 38s}  -12.61d {-12d 36' 22"}
MOON_DIST:        72.76 [deg]
MOON_ILLUM:      9 [%]
GAL_COORDS:      330.77,-28.21 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      282.23,-42.86 [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:     Sat 27 Sep 14 05:30:41 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     613775,   Seg_Num: 0
POINT_RA:        291.876d {+19h 27m 30s} (J2000)
POINT_DEC:       -65.375d {-65d 22' 28"} (J2000)
POINT_ROLL:      252.717d
IMG_START_DATE:  16927 TJD;   270 DOY;   14/09/27
IMG_START_TIME:  19790.02 SOD {05:29:50.02} UT,   878.6 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.087
N_STARS:         107
X_OFFSET:        310 [pixels]
Y_OFFSET:        207 [pixels]
X_MAX:           1749 [pixels]
Y_MAX:           1646 [pixels]
DET_THRESH:      4
PHOTO_THRESH:    2
SL_URL:          sw00613775000msufc0878.fits
SUN_POSTN:       183.71d {+12h 14m 50s}   -1.61d {-01d 36' 18"}
SUN_DIST:         96.14 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      216.22d {+14h 24m 53s}  -12.62d {-12d 37' 14"}
MOON_DIST:        72.72 [deg]
MOON_ILLUM:      9 [%]
GAL_COORDS:      330.77,-28.21 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      282.23,-42.86 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 27 Sep 14 05:31:10 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     613775,   Seg_Num: 0
POINT_RA:        291.876d {+19h 27m 30s} (J2000)
POINT_DEC:       -65.375d {-65d 22' 28"} (J2000)
POINT_ROLL:      252.717d
IMG_START_DATE:  16927 TJD;   270 DOY;   14/09/27
IMG_START_TIME:  19790.02 SOD {05:29:50.02} UT,   878.6 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.087
N_STARS:         107
X_OFFSET:        310 [pixels]
Y_OFFSET:        207 [pixels]
X_MAX:           1749 [pixels]
Y_MAX:           1646 [pixels]
DET_THRESH:      4
PHOTO_THRESH:    2
SL_URL:          sw00613775000msufc0878.fits
SUN_POSTN:       183.71d {+12h 14m 50s}   -1.61d {-01d 36' 18"}
SUN_DIST:         96.14 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      216.22d {+14h 24m 54s}  -12.62d {-12d 37' 18"}
MOON_DIST:        72.72 [deg]
MOON_ILLUM:      9 [%]
GAL_COORDS:      330.77,-28.21 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      282.23,-42.86 [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:     Sat 27 Sep 14 05:31:55 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     613775,   Seg_Num: 0
POINT_RA:        291.876d {+19h 27m 30s} (J2000)
POINT_DEC:       -65.375d {-65d 22' 28"} (J2000)
ROLL:            252.717d
IMG_START_DATE:  16927 TJD;   270 DOY;   14/09/27
IMG_START_TIME:  19790.02 SOD {05:29:50.02} UT,   878.6 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     433488602
X_OFFSET:        869 [pixels]
Y_OFFSET:        766 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1029
Y_GRB_POS:       926
BINNING_INDEX:   1
IM_URL:          sw00613775000msuni0891.fits
SUN_POSTN:       183.71d {+12h 14m 50s}   -1.61d {-01d 36' 19"}
SUN_DIST:         96.14 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      216.23d {+14h 24m 55s}  -12.62d {-12d 37' 23"}
MOON_DIST:        72.72 [deg]
MOON_ILLUM:      9 [%]
GAL_COORDS:      330.77,-28.21 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      282.23,-42.86 [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:     Sat 27 Sep 14 05:32:11 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     613775,   Seg_Num: 0
POINT_RA:        291.876d {+19h 27m 30s} (J2000)
POINT_DEC:       -65.375d {-65d 22' 28"} (J2000)
ROLL:            252.717d
IMG_START_DATE:  16927 TJD;   270 DOY;   14/09/27
IMG_START_TIME:  19790.02 SOD {05:29:50.02} UT,   878.6 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     433488602
X_OFFSET:        869 [pixels]
Y_OFFSET:        766 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1029
Y_GRB_POS:       926
BINNING_INDEX:   1
IM_URL:          sw00613775000msuni0891.fits
SUN_POSTN:       183.71d {+12h 14m 50s}   -1.61d {-01d 36' 19"}
SUN_DIST:         96.14 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      216.23d {+14h 24m 56s}  -12.62d {-12d 37' 25"}
MOON_DIST:        72.71 [deg]
MOON_ILLUM:      9 [%]
GAL_COORDS:      330.77,-28.21 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      282.23,-42.86 [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 #16842
R. L. C. Starling (U Leicester), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (NASA/GSFC), C. J. Mountford (U Leicester), K. L. Page (U Leicester), D. M. Palmer (LANL), M. H. Siegel (PSU) and T. N. Ukwatta (LANL) report on behalf of the Swift Team:
At 05:15:11 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 140927A (trigger=613775). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 291.845, -65.388 which is
```
   RA(J2000) = 19h 27m 23s
   Dec(J2000) = -65d 23' 14"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a spiky structure with a duration of about 30 sec. The peak count rate was ~1500 counts/sec (15-350 keV), at ~6 sec after the trigger.
The XRT began observing the field at 05:17:13.7 UT, 122.3 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 291.79216, -65.39285 which is equivalent to:
```
   RA(J2000)  = 19h 27m 10.12s
   Dec(J2000) = -65d 23' 34.3"
```
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This location is 81 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 (7.56 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 4 (+3.21/-2.72) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 250 seconds with the U filter starting 123 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 19.2 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 18.0 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.08.
Burst Advocate for this burst is R. L. C. Starling (rlcs1 AT star.le.ac.uk). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.)
GCN Circular #16843
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team.
Using 2980 s of XRT Photon Counting mode data and 5 UVOT images for GRB 140927A, 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 = 291.79158, -65.39357 which is equivalent to:
```
RA (J2000): 19h 27m 9.98s
Dec (J2000): -65d 23' 36.9"
```
with an uncertainty of 1.8 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177).
This circular was automatically generated, and is an official product of the Swift-XRT team.
GCN Circular #16844
J.A. Kennea (PSU), V. Mangano (PSU), M.C. Stroh (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), B.P. Gompertz (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), M. de Pasquale (INAF-IASFPA) and R.L.C. Starling report on behalf of the Swift-XRT team:
We have analysed 7.1 ks of XRT data for GRB 140927A (Starling et al. GCN Circ. 16842), from 108 s to 29.7 ks after the BAT trigger. The data comprise 7 s in Windowed Timing (WT) mode (taken while Swift was slewing), with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN Circ. 16843).
The light curve can be modelled with a power-law decay with a decay index of alpha=0.76 (+/-0.05).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.79 (+0.25, -0.23). The best-fitting absorption column is 1.6 (+1.0, -0.8) x 10^21 cm^-2, in excess of the Galactic value of 7.6 x 10^20 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 (4.8 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     1.6 (+1.0, -0.8) x 10^21 cm^-2
Galactic foreground: 7.6 x 10^20 cm^-2
Excess significance: 1.7 sigma
Photon index:	     1.79 (+0.25, -0.23)
```
If the light curve continues to decay with a power-law decay index of 0.76, the count rate at T+24 hours will be 4.7 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.8 x 10^-13 (2.3 x 10^-13) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00613775.
This circular is an official product of the Swift-XRT team.
GCN Circular #16845
S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), R. L. C. Starling (U Leicester) J. Tueller (GSFC), 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 140927A (trigger #613775) (Starling, et al., GCN Circ. 16842). The BAT ground-calculated position is RA, Dec = 291.802, -65.400 deg which is
```
  RA(J2000)  =  19h 27m 12.5s
  Dec(J2000) = -65d 23' 58.4"
```
with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 54%.
The mask-weighted light curve shows a multi-peaked structure starts at ~ T0 and ends at ~ T+9 s. The structure has roughly two main peaks, at ~ T+3.8 s and ~ T+7.7 s, respectively. T90 (15-350 keV) is 6.26 +- 1.43 sec (estimated error including systematics).
The time-averaged spectrum from T+0.43 to T+8.70 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.82 +- 0.30. The fluence in the 15-150 keV band is 2.7 +- 0.5 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+7.70 sec in the 15-150 keV band is 0.9 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/613775/BA/
GCN Circular #16846
C. Swenson (PSU) and R. L. C. Starling (U Leicester) report on behalf of the Swift UVOT team:
Analysis of the field of GRB 140927A shows a bright DSS source located at RA, DEC= 291.79237,-65.39323, which is 1.7" from the enhanced XRT position (Evans et al., GCN Circ. 16843). No elongation or fading of the known source is observed in the first 10e4 seconds of UVOT observations, meaning that any potential afterglow contribution is being overpowered by the known source.

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Jochen Greiner, last update: 28-Sep-2014 [Disclaimer]