Gamma-ray Burst 131004A

(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 04 Oct 13 21:41:19 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     573190,   Seg_Num: 0
GRB_RA:          296.151d {+19h 44m 36s} (J2000),
                 296.331d {+19h 45m 19s} (current),
                 295.498d {+19h 41m 59s} (1950)
GRB_DEC:          -2.960d {-02d 57' 35"} (J2000),
                  -2.926d {-02d 55' 33"} (current),
                  -3.081d {-03d 04' 52"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       609 [cnts]    Image_Peak=93 [image_cnts]
TRIGGER_DUR:     0.064 [sec] 
TRIGGER_INDEX:   10418     E_range: 25-100 keV
BKG_INTEN:       26591 [cnts]
BKG_TIME:        78052.88 SOD {21:40:52.88} UT
BKG_DUR:         8 [sec]
GRB_DATE:        16569 TJD;   277 DOY;   13/10/04
GRB_TIME:        78063.44 SOD {21:41:03.44} UT
GRB_PHI:         -74.29 [deg]
GRB_THETA:        20.88 [deg]
SOLN_STATUS:     0x20000003
RATE_SIGNIF:     25.72 [sigma]
IMAGE_SIGNIF:    10.17 [sigma]
MERIT_PARAMS:     +1  +0  +0  -4  +2  +0  +0  +0 +25  +0 
SUN_POSTN:       190.87d {+12h 43m 29s}   -4.67d {-04d 40' 24"}
SUN_DIST:        105.14 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      188.48d {+12h 33m 54s}   -6.39d {-06d 23' 22"}
MOON_DIST:       107.37 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:       36.39,-13.17 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      297.57, 18.01 [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 = 341.22,14.82 [deg].  
COMMENTS:           
COMMENTS:        NOTE: This BAT event is temporally(0.0<100sec) coincident with the FERMI_GBM event (trignum=402615666).

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Fri 04 Oct 13 21:41:44 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      57
TRIGGER_NUM:     402615666
GRB_RA:          319.690d {+21h 18m 46s} (J2000),
                 319.874d {+21h 19m 30s} (current),
                 319.021d {+21h 16m 05s} (1950)
GRB_DEC:          -8.950d {-08d 56' 59"} (J2000),
                  -8.892d {-08d 53' 28"} (current),
                  -9.161d {-09d 09' 39"} (1950)
GRB_ERROR:       15.52 [deg radius, statistical only]
DATA_SIGNIF:     10.90 [sigma]
DATA_INTERVAL:   0.512 [sec]
GRB_DATE:        16569 TJD;   277 DOY;   13/10/04
GRB_TIME:        78063.68 SOD {21:41:03.68} UT
GRB_PHI:         137.00 [deg]
GRB_THETA:        81.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4143 (Gnd S/W Version number)
SUN_POSTN:       190.87d {+12h 43m 29s}   -4.67d {-04d 40' 24"}
SUN_DIST:        127.38 [deg]   Sun_angle= -8.6 [hr] (East of Sun)
MOON_POSTN:      188.48d {+12h 33m 55s}   -6.39d {-06d 23' 26"}
MOON_DIST:       129.20 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:       42.38,-36.72 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      319.29,  6.40 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(0.0<100sec) coincident with the SWIFT_BAT event (trignum=573190).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Fri 04 Oct 13 21:41:29 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      47
TRIGGER_NUM:     402615666
GRB_RA:          327.633d {+21h 50m 32s} (J2000),
                 327.806d {+21h 51m 13s} (current),
                 327.007d {+21h 48m 02s} (1950)
GRB_DEC:          +5.450d {+05d 27' 00"} (J2000),
                  +5.515d {+05d 30' 53"} (current),
                  +5.216d {+05d 12' 56"} (1950)
GRB_ERROR:       21.60 [deg radius, statistical plus systematic]
GRB_INTEN:       253 [cnts/sec]
DATA_SIGNIF:     7.50 [sigma]
INTEG_TIME:      0.512 [sec]
GRB_DATE:        16569 TJD;   277 DOY;   13/10/04
GRB_TIME:        78063.68 SOD {21:41:03.68} UT
GRB_PHI:         132.98 [deg]
GRB_THETA:        65.00 [deg]
DATA_TIME_SCALE: 0.5120 [sec]
HARD_RATIO:      1.58
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      81%  GRB
2nd_MOST_LIKELY:  13%  Generic SGR
DETECTORS:       0,0,0, 0,0,0, 0,0,0, 1,1,0, 0,0,
SUN_POSTN:       190.87d {+12h 43m 29s}   -4.67d {-04d 40' 24"}
SUN_DIST:        137.11 [deg]   Sun_angle= -9.1 [hr] (East of Sun)
MOON_POSTN:      188.48d {+12h 33m 55s}   -6.39d {-06d 23' 23"}
MOON_DIST:       139.55 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:       62.70,-35.50 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      331.78, 17.40 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 20.58,1.03 [deg].  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(0.0<100sec) coincident with the SWIFT_BAT event (trignum=573190).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 04 Oct 13 21:42:25 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     573190,   Seg_Num: 0
POINT_RA:        296.173d {+19h 44m 42s} (J2000)
POINT_DEC:        -2.966d {-02d 57' 57"} (J2000)
IMG_START_DATE:  16569 TJD;   277 DOY;   13/10/04
IMG_START_TIME:  78133.41 SOD {21:42:13.41} UT,   70.0 [sec] since BAT Trigger Time
COUNTS:          7    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:     Fri 04 Oct 13 21:44:59 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     573190,   Seg_Num: 0
GRB_RA:          296.151d {+19h 44m 36s} (J2000),
                 296.331d {+19h 45m 19s} (current),
                 295.498d {+19h 41m 59s} (1950)
GRB_DEC:          -2.960d {-02d 57' 35"} (J2000),
                  -2.926d {-02d 55' 33"} (current),
                  -3.081d {-03d 04' 52"} (1950)
GRB_DATE:        16569 TJD;   277 DOY;   13/10/04
GRB_TIME:        78063.68 SOD {21:41:03.68} UT
TRIGGER_INDEX:   10418
GRB_PHI:         -74.29 [deg]
GRB_THETA:        20.88 [deg]
DELTA_TIME:      40.00 [sec]
TRIGGER_DUR:     0.064 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     25.72 [sigma]
IMAGE_SIGNIF:    10.17 [sigma]
LC_URL:          sw00573190000msb.lc
SUN_POSTN:       190.87d {+12h 43m 30s}   -4.67d {-04d 40' 27"}
SUN_DIST:        105.14 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      188.51d {+12h 34m 02s}   -6.40d {-06d 24' 01"}
MOON_DIST:       107.34 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:       36.39,-13.17 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      297.57, 18.01 [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 = 341.22,14.82 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 04 Oct 13 21:45:37 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     573190,   Seg_Num: 0
POINT_RA:        296.174d {+19h 44m 42s} (J2000)
POINT_DEC:        -2.966d {-02d 57' 56"} (J2000)
POINT_ROLL:      264.339d
IMG_START_DATE:  16569 TJD;   277 DOY;   13/10/04
IMG_START_TIME:  78138.86 SOD {21:42:18.86} UT,   75.4 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.991
N_STARS:         190
X_OFFSET:        662 [pixels]
Y_OFFSET:        526 [pixels]
X_MAX:           1621 [pixels]
Y_MAX:           1485 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    8
SL_URL:          sw00573190000msufc0075.fits
SUN_POSTN:       190.87d {+12h 43m 30s}   -4.67d {-04d 40' 28"}
SUN_DIST:        105.16 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      188.52d {+12h 34m 04s}   -6.40d {-06d 24' 08"}
MOON_DIST:       107.36 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:       36.40,-13.20 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      297.59, 18.00 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 04 Oct 13 21:46:22 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     573190,   Seg_Num: 0
POINT_RA:        296.174d {+19h 44m 42s} (J2000)
POINT_DEC:        -2.966d {-02d 57' 56"} (J2000)
POINT_ROLL:      264.339d
IMG_START_DATE:  16569 TJD;   277 DOY;   13/10/04
IMG_START_TIME:  78138.86 SOD {21:42:18.86} UT,   75.4 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.991
N_STARS:         190
X_OFFSET:        662 [pixels]
Y_OFFSET:        526 [pixels]
X_MAX:           1621 [pixels]
Y_MAX:           1485 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    8
SL_URL:          sw00573190000msufc0075.fits
SUN_POSTN:       190.87d {+12h 43m 30s}   -4.67d {-04d 40' 28"}
SUN_DIST:        105.16 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      188.52d {+12h 34m 05s}   -6.40d {-06d 24' 16"}
MOON_DIST:       107.35 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:       36.40,-13.20 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      297.59, 18.00 [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 04 Oct 13 21:47:03 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     573190,   Seg_Num: 0
POINT_RA:        296.174d {+19h 44m 42s} (J2000)
POINT_DEC:        -2.966d {-02d 57' 56"} (J2000)
ROLL:            264.339d
IMG_START_DATE:  16569 TJD;   277 DOY;   13/10/04
IMG_START_TIME:  78138.86 SOD {21:42:18.86} UT,   75.4 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     402615749
X_OFFSET:        981 [pixels]
Y_OFFSET:        845 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1141
Y_GRB_POS:       1005
BINNING_INDEX:   1
IM_URL:          sw00573190000msuni0087.fits
SUN_POSTN:       190.87d {+12h 43m 30s}   -4.68d {-04d 40' 29"}
SUN_DIST:        105.16 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      188.53d {+12h 34m 07s}   -6.41d {-06d 24' 23"}
MOON_DIST:       107.34 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:       36.40,-13.20 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      297.59, 18.00 [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 04 Oct 13 21:47:08 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     573190,   Seg_Num: 0
GRB_RA:          296.1154d {+19h 44m 27.69s} (J2000),
                 296.2952d {+19h 45m 10.85s} (current),
                 295.4617d {+19h 41m 50.79s} (1950)
GRB_DEC:          -2.9575d {-02d 57' 27.0"} (J2000),
                  -2.9237d {-02d 55' 25.2"} (current),
                  -3.0786d {-03d 04' 43.0"} (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:  16569 TJD;   277 DOY;   13/10/04
IMG_START_TIME:  78151.00 SOD {21:42:31.00} UT,   87.6 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       190.87d {+12h 43m 30s}   -4.68d {-04d 40' 29"}
SUN_DIST:        105.10 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      188.53d {+12h 34m 07s}   -6.41d {-06d 24' 24"}
MOON_DIST:       107.29 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:       36.38,-13.14 [deg] galactic lon,lat of the burst
ECL_COORDS:      297.53, 18.02 [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:     Fri 04 Oct 13 21:47:21 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     573190,   Seg_Num: 0
POINT_RA:        296.174d {+19h 44m 42s} (J2000)
POINT_DEC:        -2.966d {-02d 57' 56"} (J2000)
ROLL:            264.339d
IMG_START_DATE:  16569 TJD;   277 DOY;   13/10/04
IMG_START_TIME:  78138.86 SOD {21:42:18.86} UT,   75.4 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     402615749
X_OFFSET:        981 [pixels]
Y_OFFSET:        845 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1141
Y_GRB_POS:       1005
BINNING_INDEX:   1
IM_URL:          sw00573190000msuni0087.fits
SUN_POSTN:       190.87d {+12h 43m 30s}   -4.68d {-04d 40' 29"}
SUN_DIST:        105.16 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      188.53d {+12h 34m 07s}   -6.41d {-06d 24' 26"}
MOON_DIST:       107.34 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:       36.40,-13.20 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      297.59, 18.00 [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 #15303
L. M. Z. Hagen (PSU), D. N. Burrows (PSU), V. D'Elia (ASDC), N. Gehrels (NASA/GSFC), J. A. Kennea (PSU), V. Mangano (PSU), F. E. Marshall (NASA/GSFC) and B. Sbarufatti (INAF-OAB/PSU) report on behalf of the Swift Team:
At 21:41:03 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 131004A (trigger=573190). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 296.151, -2.960 which is
```
   RA(J2000) = 19h 44m 36s
   Dec(J2000) = -02d 57' 35"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single-peaked structure with a duration of about 2 sec. The peak count rate was ~8500 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 21:42:13.4 UT, 70.0 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 296.11549, -2.95806 which is equivalent to:
```
   RA(J2000)  = 19h 44m 27.72s
   Dec(J2000) = -02d 57' 29.0"
```
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This location is 127 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 (6.97 x 10^20 cm^-2, Kalberla et al. 2005), with an excess column of 4.5 (+2.61/-2.22) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 75 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 BAT 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 0.28.
Burst Advocate for this burst is L. M. Z. Hagen (lea.zernow.hagen AT gmail.com). 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 04 Oct 13 21:54:54 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     573190,   Seg_Num: 0
POINT_RA:        296.176d {+19h 44m 42s} (J2000)
POINT_DEC:        -2.966d {-02d 57' 57"} (J2000)
POINT_ROLL:      264.339d
IMG_START_DATE:  16569 TJD;   277 DOY;   13/10/04
IMG_START_TIME:  78351.02 SOD {21:45:51.02} UT,   287.6 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.855
N_STARS:         190
X_OFFSET:        422 [pixels]
Y_OFFSET:        286 [pixels]
X_MAX:           1861 [pixels]
Y_MAX:           1725 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    4
SL_URL:          sw00573190000msufc0287.fits
SUN_POSTN:       190.88d {+12h 43m 31s}   -4.68d {-04d 40' 37"}
SUN_DIST:        105.16 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      188.60d {+12h 34m 23s}   -6.43d {-06d 25' 47"}
MOON_DIST:       107.28 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:       36.40,-13.20 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      297.60, 18.00 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 04 Oct 13 21:55:21 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     573190,   Seg_Num: 0
POINT_RA:        296.176d {+19h 44m 42s} (J2000)
POINT_DEC:        -2.966d {-02d 57' 57"} (J2000)
POINT_ROLL:      264.339d
IMG_START_DATE:  16569 TJD;   277 DOY;   13/10/04
IMG_START_TIME:  78351.02 SOD {21:45:51.02} UT,   287.6 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.855
N_STARS:         190
X_OFFSET:        422 [pixels]
Y_OFFSET:        286 [pixels]
X_MAX:           1861 [pixels]
Y_MAX:           1725 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    4
SL_URL:          sw00573190000msufc0287.fits
SUN_POSTN:       190.88d {+12h 43m 31s}   -4.68d {-04d 40' 37"}
SUN_DIST:        105.16 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      188.60d {+12h 34m 24s}   -6.43d {-06d 25' 52"}
MOON_DIST:       107.27 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:       36.40,-13.20 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      297.60, 18.00 [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 04 Oct 13 21:55:52 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     573190,   Seg_Num: 0
POINT_RA:        296.176d {+19h 44m 42s} (J2000)
POINT_DEC:        -2.966d {-02d 57' 57"} (J2000)
ROLL:            264.339d
IMG_START_DATE:  16569 TJD;   277 DOY;   13/10/04
IMG_START_TIME:  78351.02 SOD {21:45:51.02} UT,   287.6 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     402615962
X_OFFSET:        981 [pixels]
Y_OFFSET:        845 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1141
Y_GRB_POS:       1005
BINNING_INDEX:   1
IM_URL:          sw00573190000msuni0299.fits
SUN_POSTN:       190.88d {+12h 43m 31s}   -4.68d {-04d 40' 38"}
SUN_DIST:        105.15 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      188.61d {+12h 34m 25s}   -6.43d {-06d 25' 57"}
MOON_DIST:       107.27 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:       36.40,-13.20 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      297.60, 18.00 [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 04 Oct 13 21:56:03 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     573190,   Seg_Num: 0
POINT_RA:        296.176d {+19h 44m 42s} (J2000)
POINT_DEC:        -2.966d {-02d 57' 57"} (J2000)
ROLL:            264.339d
IMG_START_DATE:  16569 TJD;   277 DOY;   13/10/04
IMG_START_TIME:  78351.02 SOD {21:45:51.02} UT,   287.6 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     402615962
X_OFFSET:        981 [pixels]
Y_OFFSET:        845 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1141
Y_GRB_POS:       1005
BINNING_INDEX:   1
IM_URL:          sw00573190000msuni0299.fits
SUN_POSTN:       190.88d {+12h 43m 31s}   -4.68d {-04d 40' 38"}
SUN_DIST:        105.15 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      188.61d {+12h 34m 26s}   -6.43d {-06d 26' 00"}
MOON_DIST:       107.27 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:       36.40,-13.20 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      297.60, 18.00 [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:     Fri 04 Oct 13 21:56:35 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     573190,   Seg_Num: 0
GRB_RA:          296.1132d {+19h 44m 27.16s} (J2000),
                 296.2930d {+19h 45m 10.32s} (current),
                 295.4595d {+19h 41m 50.26s} (1950)
GRB_DEC:          -2.9588d {-02d 57' 31.6"} (J2000),
                  -2.9250d {-02d 55' 29.9"} (current),
                  -3.0799d {-03d 04' 47.6"} (1950)
GRB_ERROR:       2.2 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  16569 TJD;   277 DOY;   13/10/04
IMG_START_TIME:  78151.00 SOD {21:42:31.00} UT,   87.6 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       190.88d {+12h 43m 31s}   -4.68d {-04d 40' 38"}
SUN_DIST:        105.09 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      188.61d {+12h 34m 27s}   -6.44d {-06d 26' 05"}
MOON_DIST:       107.20 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:       36.37,-13.14 [deg] galactic lon,lat of the burst
ECL_COORDS:      297.53, 18.02 [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 04 Oct 13 22:02:15 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     573190,   Seg_Num: 0
POINT_RA:        296.176d {+19h 44m 42s} (J2000)
POINT_DEC:        -2.966d {-02d 57' 58"} (J2000)
POINT_ROLL:      264.339d
IMG_START_DATE:  16569 TJD;   277 DOY;   13/10/04
IMG_START_TIME:  78928.58 SOD {21:55:28.58} UT,   865.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.774
N_STARS:         190
X_OFFSET:        422 [pixels]
Y_OFFSET:        286 [pixels]
X_MAX:           1861 [pixels]
Y_MAX:           1725 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    7
SL_URL:          sw00573190000msufc0865.fits
SUN_POSTN:       190.88d {+12h 43m 32s}   -4.68d {-04d 40' 44"}
SUN_DIST:        105.15 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      188.66d {+12h 34m 39s}   -6.45d {-06d 27' 06"}
MOON_DIST:       107.21 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:       36.40,-13.20 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      297.59, 18.00 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 04 Oct 13 22:02:46 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     573190,   Seg_Num: 0
POINT_RA:        296.176d {+19h 44m 42s} (J2000)
POINT_DEC:        -2.966d {-02d 57' 58"} (J2000)
POINT_ROLL:      264.339d
IMG_START_DATE:  16569 TJD;   277 DOY;   13/10/04
IMG_START_TIME:  78928.58 SOD {21:55:28.58} UT,   865.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.774
N_STARS:         190
X_OFFSET:        422 [pixels]
Y_OFFSET:        286 [pixels]
X_MAX:           1861 [pixels]
Y_MAX:           1725 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    7
SL_URL:          sw00573190000msufc0865.fits
SUN_POSTN:       190.88d {+12h 43m 32s}   -4.68d {-04d 40' 44"}
SUN_DIST:        105.15 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      188.67d {+12h 34m 40s}   -6.45d {-06d 27' 11"}
MOON_DIST:       107.20 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:       36.40,-13.20 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      297.59, 18.00 [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 04 Oct 13 22:04:05 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     573190,   Seg_Num: 0
POINT_RA:        296.176d {+19h 44m 42s} (J2000)
POINT_DEC:        -2.966d {-02d 57' 58"} (J2000)
ROLL:            264.339d
IMG_START_DATE:  16569 TJD;   277 DOY;   13/10/04
IMG_START_TIME:  78928.58 SOD {21:55:28.58} UT,   865.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     402616539
X_OFFSET:        981 [pixels]
Y_OFFSET:        845 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1141
Y_GRB_POS:       1005
BINNING_INDEX:   1
IM_URL:          sw00573190000msuni0877.fits
SUN_POSTN:       190.89d {+12h 43m 33s}   -4.68d {-04d 40' 45"}
SUN_DIST:        105.15 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      188.68d {+12h 34m 43s}   -6.46d {-06d 27' 25"}
MOON_DIST:       107.19 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:       36.40,-13.20 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      297.59, 18.00 [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 04 Oct 13 22:04:22 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     573190,   Seg_Num: 0
POINT_RA:        296.176d {+19h 44m 42s} (J2000)
POINT_DEC:        -2.966d {-02d 57' 58"} (J2000)
ROLL:            264.339d
IMG_START_DATE:  16569 TJD;   277 DOY;   13/10/04
IMG_START_TIME:  78928.58 SOD {21:55:28.58} UT,   865.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     402616539
X_OFFSET:        981 [pixels]
Y_OFFSET:        845 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1141
Y_GRB_POS:       1005
BINNING_INDEX:   1
IM_URL:          sw00573190000msuni0877.fits
SUN_POSTN:       190.89d {+12h 43m 33s}   -4.68d {-04d 40' 46"}
SUN_DIST:        105.15 [deg]   Sun_angle= -7.0 [hr] (East of Sun)
MOON_POSTN:      188.68d {+12h 34m 44s}   -6.46d {-06d 27' 28"}
MOON_DIST:       107.19 [deg]
MOON_ILLUM:      0 [%]
GAL_COORDS:       36.40,-13.20 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      297.59, 18.00 [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 #15304
D. Xu, D. Malesani, J. Hjorth (DARK/NBI), P. Jakobsson (Univ. Iceland), T. Kruehler (ESO Santiago), Nicolaas Groeneboom, and Anders Hafreager (Univ. Oslo), report:
We observed the field of GRB 131004A (Hagen et al., GCN 15303) using the NOT equipped with AlFOSC. Consistent with the XRT position, we detect a new source at coordinates:
```
RA = 19:44:27.08
Dec = -02:57:30.2
```
The source is not visible in the DSS, and brighter than its limiting magnitude, hence it is very likely the afterglow of GRB 131004A. At a time of 0.43 hr after the GRB, we measure R = 20.2 +- 0.1 mag compared to nearby USNO-B1 R2 magnitudes, where the error is mostly due to calibration.
GCN Circular #15305
D. Malesani (DARK/NBI), P. D'Avanzo (INAF-OAB), L. di Fabrizio, G. Tessicini (INAF-TNG) report on behalf of the CIBO collaboration:
We observed the field of the possible short GRB 131004A (Hagen et al. GCN 15303) with the Italian 3.6m TNG telescope located in Canary Islands, equipped with the DOLoRes imager.
The optical candidate reported by Xu et al (GCN 15304) is clearly seen in a 60 s R-band image taken at a mid t-t0=1.1 hours. From a preliminary photometry we estimate for this source a magnitude of R = 20.8 +/- 0.1 (calibrated against the USNOB1 catalogue).
Given the evidence of fading with respect to the report of Xu et al. (GCN 15304) we confirm this source as the optical afterglow of GRB 131004A. The inferred power-law decay index is alpha=0.59 +/- 0.15.
We acknowledge the TNG visitor astronomer X. Dumesque for support.
GCN Circular #15306
D. Kopac (U. Ljubljana), R. J. Smith (LJMU), C. G. Mundell (LJMU), N. R. Tanvir (U. Leicester) and A. Gomboc (U. Ljubljana), on behalf of a large collaboration report:
The 2-m Liverpool Telescope automatically began observing the field of GRB 131004A (Hagen et al., GCN 15303). We detect the optical afterglow in the position consistent with the NOT (Xu et al., GCN 15304) and TNG (Malesani et al., GCN 15305). Our preliminary photometry yields:
```
Mid time from   Exp    Filter   Magnitude
trigger (min)   (sec)
-------------------------------------------
85.1            300    i'       20.2 +- 0.1
111.3           300    i'       20.6 +- 0.1
-------------------------------------------
```
The magnitudes are calibrated agains I magnitudes of nearby USNO-B1.0 stars and are not corrected for the Galactic extinction.
GCN Circular #15307
R. Chornock, R. Lunnan, and E. Berger (Harvard) report:
We observed the optical afterglow (Xu et al., GCN 15304; Malesani et al., GCN 15305; Kopac et al., GCN 15306) of the possible short GRB 131004A (Hagen et al., GCN 15303) using LDSS-3 on the 6.5-m Magellan Clay Telescope. A sequence of 3x1200s spectroscopic exposures of the afterglow began at 23:44 on 4 October UT. A preliminary reduction reveals a flat continuum with superposed weak emission lines from [O II], H-beta, and [O III] at a common redshift of 0.717. Possible weak features consistent with Ca II H+K absorption at this same redshift are also present.
GCN Circular #15308
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team.
Using 465 s of XRT Photon Counting mode data and 1 UVOT images for GRB 131004A, 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 = 296.11332, -2.95861 which is equivalent to:
```
RA (J2000): 19h 44m 27.20s
Dec (J2000): -02d 57' 31.0"
```
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 #15309
S. Schmidl, A. Nicuesa Guelbenzu, S. Klose (all TLS Tautenburg), and J. Greiner (MPE Garching) report on behalf of the GROND team:
We observed the field of GRB 131004A (Swift trigger 573190; Hagen et al., GCN 15303) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2m MPG telescope at ESO La Silla Observatory (Chile).
Observations started on October 4, 2013, at 23:41 UT, 2 hrs after the GRB trigger. They were performed at an average seeing of 0".9 and at an average airmass of 1.1.
The optical afterglow, discovered by Xu et al. (GCN 15304), is clearly detected.
Based on a total exposure time of 460 s in g'r'i'z' and 480 s in JHK, at a midtime of 2.75 hrs after the burst, we measure the following preliminary AB magnitudes:
```
g' = 22.9 +/- 0.1,
r' = 22.1 +/- 0.1,
i' = 21.6 +/- 0.1,
z' = 21.4 +/- 0.1,
J = 20.2 +/- 0.2,
H = 20.2 +/- 0.2, and
K > 19.8 .
```
Given magnitudes are calibrated against GROND zeropoints as well as 2MASS field stars and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.29 mag in the direction of the burst (Schlegel et al. 1998).
GCN Circular #15310
V. D'Elia (INAF-OAR/ASDC), P. D'Avanzo (INAF-OAB), D. Malesani (DARK/NBI), L. di Fabrizio, G. Tessicini (INAF-TNG) report on behalf of the CIBO collaboration:
We observed the optical afterglow (Xu et al., GCN 15304; Malesani et al., GCN 15305; Kopac et al., GCN 15306) of the possible short GRB 131004A (Hagen et al., GCN 15303) using DOLORES/LR-B (wavelength range: 3000-8000 AA) on the 4-m TNG Telescope at Canary islands. We obtain a 1800 s spectrum starting at 2013-10-04 23:00:38 UT, i.e., 1.33 hr from the burst.
A preliminary reduction reveals weak emission lines from [O II], H-gamma and H-delta at a common redshift of 0.71.
We thus confirm the redshift reported by Chornock et al. (GCN 15307).
GCN Circular #15311
C. Pagani (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. Maselli (INAF-IASFPA), D.N. Burrows (PSU), J.A. Kennea (PSU), V. Mangano (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester) and report on behalf of the Swift-XRT team: report on behalf of the Swift-XRT team:
We have analysed 9.1 ks of XRT data for GRB 131004A, from 79 s to 34.7 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. the light curve is consistent with a constant source of mean count rate 7.4e-02 ct/sec. A power-law fit gives an index of 0.1 (+2.0, -1.6).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.16 (+0.27, -0.26). The best-fitting absorption column is 3.1 (+1.0, -0.9) x 10^21 cm^-2, in excess of the Galactic value of 7.0 x 10^20 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.9 x 10^-11 (6.8 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     3.1 (+1.0, -0.9) x 10^21 cm^-2
Galactic foreground: 7.0 x 10^20 cm^-2
Excess significance: 4.7 sigma
Photon index:	     2.16 (+0.27, -0.26)
```
If the light curve continues to decay with a power-law decay index of 0.1, the count rate at T+24 hours will be 0.029 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.1 x 10^-12 (1.9 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/00573190.
This circular is an official product of the Swift-XRT team.
GCN Circular #15312
Owen Littlejohns (ASU), Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC), Eleonora Troja (GSFC), Enrico Ramirez-Ruiz (UCSC), Jos=E9 A. de Diego (UNAM), Leonid Georgiev (UNAM), Jes=FAs Gonz=E1lez (UNAM), Carlos Rom=E1n-Z=FA=F1iga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC) report:
We observed the field of GRB 131004A (Hagen, et al., GCN 15303) 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 2013/10 5.12 to 2013/10 5.30 UTC (5.12 to 9.44 hours after the BAT trigger), obtaining a total of 2.17 hours exposure in the r and i bands and 0.94 hours exposure in the Z, Y, J, and H bands.
For a source within the Swift-XRT error circle, in comparison with 2MASS,= we obtain the following upper limits (3-sigma):
```
  r     > 23.91
  i     > 23.33
  Z     > 22.56
  Y     > 21.86
  J     > 21.81
  H     > 21.26
```
These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. We did not detect the source reported in Xu et al. (GCN 15304). In comparison with earlier GROND observations (Schmidl, et al., GCN 15309) the source has faded by a minimum of 1.7 magnitudes in the r band. This implies a power-law decay steeper than t^-1.7.
We thank the staff of the Observatorio Astron=F3mico Nacional in San Pedro M=E1rtir.
GCN Circular #15313
M. De Pasquale (UCL-MSSL) and L. M. Z. Hagen (PSU) report on behalf of th= e Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 131004A 75 s after the BAT trigger (Hagen et al., GCN Circ. 15303). A source consistent with the XRT position (Evans et al. GCN Circ. 15308) and the position of the source given in Xu et al. (GCN Circ. 15304) is detected in the initial and summed UVOT exposures.
The preliminary coordinates of this source are:
```
    RA  (J2000) =3D  19:44:27.09 =3D 296.11287 (deg.)
    Dec (J2000) =3D -02:57:30.4  =3D  -2.95844 (deg.)
```
with an estimated uncertainty of 0.55 arc sec. (radius, 90% confidence).
Preliminary detections and 3-sigma upper limits using the UVOT photometri= c system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white_FC            75          225          147         19.23 =C2=B1 0.1=
1
white               75         5688          520         20.18 =C2=B1 0.1=
2

u_FC               288          537          246         19.96 =C2=B1 0.3=
4
u                  288         6715          659         20.72 =C2=B1 0.4=
0

v                  617         6100          432         >20.24
b                  543         6770          285         >21.0

w1                 666         6510          432         >20.9
m2                 814         6305          413         >20.8
w2                 593         5895          432         >21.0
```
The magnitudes in the table are not corrected for substantial Galactic extinction due to the reddening of E(B-V) =3D 0.28 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #15314
B. A. Zauderer, E. Berger, W. Fong (Harvard) report on behalf of a larger collaboration and the CARMA Key Project "A Millimeter View of the Transient Universe":
"We observed the position of GRB 131004A (Hagen et al., GCN 15303) with CARMA at a mean frequency of 93 GHz beginning 2013 October 5.04 (dt=3.4 hours). We do not find significant radio emission at the position of the enhanced Swift-XRT and UVOT localizations (Evans et al., GCN 15308; De Pasquale et al., GCN 15313), or the optical afterglow detection (Xu et al., GCN 15304), to a 3-sigma upper limit of ~0.3 mJy. No further radio observations are planned.
We thank the CARMA staff for prompt execution of these observations."
GCN Circular #15315
Shaolin Xiong (UAH) reports on behalf of the Fermi GBM Team:
"At 21:41:03.68 UT on 04 October 2013, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 131004A (trigger 402615666 / 131004904), which was also detected by the Swift/BAT (Hagen et al. 2013, GCN 15303). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 93 degrees.
The GBM light curve consists of multiple pulses with a duration (T90) of about 1.4 s (50-300 keV). The time-averaged spectrum from T0-0.19 s to T0+0.58 s is well fit by a simple power law function with index -1.75 +/- 0.06.
The event fluence (10-1000 keV) in this time interval is (6.2 +/- 0.6)E-7 erg/cm^2. The 64 ms peak photon flux measured starting from T0+0.192 s in the 10-1000 keV band is 10.4 +/- 1.6 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN Circular #15316
M. Stamatikos (OSU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), L. M. Z. Hagen (PSU), H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/GSFC/ORAU), C. B. Markwardt (GSFC), J. Norris (BSU), D. M. Palmer (LANL), T. Sakamoto (AGU), G. Sato (ISAS), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team):
Using the data set from T30 to T+62 sec from the recent telemetry downlink, we report further analysis of BAT GRB 131004A (trigger #573190) (Hagen, et al., GCN Circ. 15303). The BAT ground-calculated position is RA, Dec = 296.108, -2.952 deg which is
```
  RA(J2000)  =  19h 44m 26.0s
  Dec(J2000) = -02d 57' 05.6"
```
with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 73%.
The mask-weighted light curve shows a single short spike starts at ~T-0.18, peaks at ~T0, and ends at ~T+1.35. T90 (15-350 keV) is 1.54 +- 0.33 sec (estimated error including systematics).
The time-averaged spectrum from T-0.25 to T+1.80 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.81 +- 0.11. The fluence in the 15-150 keV band is 2.8 +- 0.2 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T-0.27 sec in the 15-150 keV band is 3.4 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
The burst spectrum appears at the softer end of short bursts, which have an average spectral index of 1.2 when fitting with a simple power-law model (Sakamoto et al. 2011). The spectral lag for this burst is 0.130 s +- 0.020 s (for the 50-100 keV and 15-25 keV bands), which is significantly longer than those of regular short bursts.
The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/573190/BA/
GCN Circular #15317
N. Frank, A. Trotter, D. Reichart, J. Haislip, A. LaCluyze, A. Smith, D. Caton, L. Hawkins, T. Berger, H. T. Cromartie, R. Egger, A. Foster, K. Ivarsen, M. Maples, J. Moore, M. Nysewander, E. Speckhard, and J. A. Crain report:
Skynet observed the Swift/XRT localization of the field of GRB 131004A (Hagen et al., GCN 15303, Swift trigger # 573190) with four 16" telescopes of the PROMPT array at CTIO, Chile and with the 14" telescope at the Appalachian State University Dark Sky Observatory (DSO), North Carolina, starting at 2013-10-04, 23:39:35 UT and continuing until 2013-10-05, 02:21:12 UT (t=1.9-4.7h post-trigger).
Skynet took a total of 220 160s exposures simultaneously in each of the BVRI bands. In stacked images, we do not detect any uncatalogued optical source in any band at or near the reported position. The 3-sigma limiting magnitudes of our images are:
```
========================================================================
t(mean)   telescope        band      exposures           3-sig lim mag
-------------------------------------------------------------------------
2.5h       Prompt3             B          25x160s                18.98
2.7h       Prompt1             V          32x160s                21.56
3.4h       Prompt4             R          55x160s                21.85
3.5h       Prompt5             I          50x160s                21.12
2.9h       DSO-14              I          7x160s                 18.46
=========================================================================
```
Magnitudes are in the Vega system, calibrated to five APASS stars in the field. Magnitudes have not been corrected for line-of-sight Milky Way dust extinction, with expected E(B-V)=0.28 (Schlegel et al. 1998).
No further Skynet observations are scheduled.
GCN Circular #15318
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team,
There was a mistake in the "Swift-XRT refined analysis" circular (GCN Circ. 15311) in which it was erroneously stated that the light curve was consistent with a constant source. In fact, the light curve is decaying as a power-law with an index of 1.01 (+/- 0.07). We apologise for any confusion caused. As ever, the full light curve and related GRB products are online at http://www.swift.ac.uk/xrt_products/00573190
This circular is an official product of the Swift-XRT team.
GCN Circular #15319
D. A. Perley (Caltech) reports:
I imaged the location of GRB 131004A (GCN 15303) in Ks-band with MOSFIRE on the Keck I telescope on the night of 2013-10-07 for a total integration time of 291 seconds under good seeing conditions but some cloud cover. The midpoint of the integration was 07:21 UT, 2.40 days after the GRB.
At the location of the optical transient reported by Xu et al. (GCN 15304), no source is detected to a limiting magnitude of Ks > 20.6. The nearest detected object to this location is a faint (Ks = 19.7), compact source approximately 1.4 arcsec to the west, at RA=19:44:26.99, dec=-02:57:30.15.
Given the moderate redshift of z=0.717 (Chornock et al., GCN 15307), these results suggest either that the host of this event is a relatively low-mass galaxy or that the GRB exploded outside the bulk of the stellar light of its host. The >1.5 sec duration and significant lag reported in the BAT refined analysis (Lien et al., GCN 15316) may suggest the former interpretation is more likely.
I thank D. Malesani for providing the NOT image to verity the location of the optical transient.

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Jochen Greiner, last update: 08-Oct-2013 [Disclaimer]