Gamma-ray Burst 160504A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 04 May 16 19:31:20 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     685124,   Seg_Num: 0
GRB_RA:          170.043d {+11h 20m 10s} (J2000),
                 170.276d {+11h 21m 06s} (current),
                 169.329d {+11h 17m 19s} (1950)
GRB_DEC:         +55.997d {+55d 59' 48"} (J2000),
                 +55.907d {+55d 54' 25"} (current),
                 +56.271d {+56d 16' 14"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       12232 [cnts]    Image_Peak=286 [image_cnts]
TRIGGER_DUR:     4.096 [sec] 
TRIGGER_INDEX:   298     E_range: 25-100 keV
BKG_INTEN:       105330 [cnts]
BKG_TIME:        70183.77 SOD {19:29:43.77} UT
BKG_DUR:         40 [sec]
GRB_DATE:        17512 TJD;   125 DOY;   16/05/04
GRB_TIME:        70237.34 SOD {19:30:37.34} UT
GRB_PHI:          43.00 [deg]
GRB_THETA:        17.13 [deg]
SOLN_STATUS:     0x83
RATE_SIGNIF:     13.78 [sigma]
IMAGE_SIGNIF:    6.82 [sigma]
MERIT_PARAMS:     +1  +0  +0  +2  +2  -3  +0  +0  +9  +0 
SUN_POSTN:        42.29d {+02h 49m 10s}  +16.26d {+16d 15' 45"}
SUN_DIST:         95.70 [deg]   Sun_angle= -8.5 [hr] (East of Sun)
MOON_POSTN:       16.17d {+01h 04m 42s}   +4.36d {+04d 21' 22"}
MOON_DIST:       116.10 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:      146.26, 56.80 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      142.77, 46.23 [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:        Since the IMAGE_SIGNIF is less than 7 sigma, this is a questionable detection.  
COMMENTS:        This trigger occurred at longitude,latitude = 50.86,20.40 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 04 May 16 19:34:05 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     685124,   Seg_Num: 0
GRB_RA:          170.043d {+11h 20m 10s} (J2000),
                 170.276d {+11h 21m 06s} (current),
                 169.329d {+11h 17m 19s} (1950)
GRB_DEC:         +55.997d {+55d 59' 48"} (J2000),
                 +55.907d {+55d 54' 25"} (current),
                 +56.271d {+56d 16' 14"} (1950)
GRB_DATE:        17512 TJD;   125 DOY;   16/05/04
GRB_TIME:        70237.34 SOD {19:30:37.34} UT
TRIGGER_INDEX:   298
GRB_PHI:          43.00 [deg]
GRB_THETA:        17.13 [deg]
DELTA_TIME:      -76.00 [sec]
TRIGGER_DUR:     4.096 [sec] 
SOLN_STATUS:     0x83
RATE_SIGNIF:     13.78 [sigma]
IMAGE_SIGNIF:    6.82 [sigma]
LC_URL:          sw00685124000msb.lc
SUN_POSTN:        42.29d {+02h 49m 10s}  +16.26d {+16d 15' 47"}
SUN_DIST:         95.70 [deg]   Sun_angle= -8.5 [hr] (East of Sun)
MOON_POSTN:       16.20d {+01h 04m 49s}   +4.37d {+04d 21' 54"}
MOON_DIST:       116.08 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:      146.26, 56.80 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      142.77, 46.23 [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:        Since the IMAGE_SIGNIF is less than 7 sigma, this is a questionable detection.  
COMMENTS:        This trigger occurred at longitude,latitude = 50.86,20.40 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 04 May 16 19:35:04 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     685124,   Seg_Num: 0
POINT_RA:        170.011d {+11h 20m 03s} (J2000)
POINT_DEC:       +56.004d {+56d 00' 15"} (J2000)
POINT_ROLL:      310.305d
IMG_START_DATE:  17512 TJD;   125 DOY;   16/05/04
IMG_START_TIME:  70336.23 SOD {19:32:16.23} UT,   98.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.551
N_STARS:         27
X_OFFSET:        368 [pixels]
Y_OFFSET:        688 [pixels]
X_MAX:           1327 [pixels]
Y_MAX:           1647 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00685124000msufc0098.fits
SUN_POSTN:        42.29d {+02h 49m 10s}  +16.26d {+16d 15' 47"}
SUN_DIST:         95.68 [deg]   Sun_angle= -8.5 [hr] (East of Sun)
MOON_POSTN:       16.21d {+01h 04m 51s}   +4.37d {+04d 22' 06"}
MOON_DIST:       116.06 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:      146.28, 56.78 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      142.75, 46.23 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 04 May 16 19:35:31 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     685124,   Seg_Num: 0
POINT_RA:        170.011d {+11h 20m 03s} (J2000)
POINT_DEC:       +56.004d {+56d 00' 15"} (J2000)
ROLL:            310.305d
IMG_START_DATE:  17512 TJD;   125 DOY;   16/05/04
IMG_START_TIME:  70336.23 SOD {19:32:16.23} UT,   98.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     484083152
X_OFFSET:        673 [pixels]
Y_OFFSET:        1111 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       833
Y_GRB_POS:       1271
BINNING_INDEX:   1
IM_URL:          sw00685124000msuni0115.fits
SUN_POSTN:        42.29d {+02h 49m 11s}  +16.26d {+16d 15' 48"}
SUN_DIST:         95.68 [deg]   Sun_angle= -8.5 [hr] (East of Sun)
MOON_POSTN:       16.22d {+01h 04m 52s}   +4.37d {+04d 22' 11"}
MOON_DIST:       116.06 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:      146.28, 56.78 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      142.75, 46.23 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 04 May 16 19:35:37 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     685124,   Seg_Num: 0
POINT_RA:        170.011d {+11h 20m 03s} (J2000)
POINT_DEC:       +56.004d {+56d 00' 15"} (J2000)
POINT_ROLL:      310.305d
IMG_START_DATE:  17512 TJD;   125 DOY;   16/05/04
IMG_START_TIME:  70336.23 SOD {19:32:16.23} UT,   98.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.551
N_STARS:         27
X_OFFSET:        368 [pixels]
Y_OFFSET:        688 [pixels]
X_MAX:           1327 [pixels]
Y_MAX:           1647 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00685124000msufc0098.fits
SUN_POSTN:        42.29d {+02h 49m 11s}  +16.26d {+16d 15' 48"}
SUN_DIST:         95.68 [deg]   Sun_angle= -8.5 [hr] (East of Sun)
MOON_POSTN:       16.22d {+01h 04m 52s}   +4.37d {+04d 22' 12"}
MOON_DIST:       116.06 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:      146.28, 56.78 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      142.75, 46.23 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 04 May 16 19:35:46 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     685124,   Seg_Num: 0
POINT_RA:        170.011d {+11h 20m 03s} (J2000)
POINT_DEC:       +56.004d {+56d 00' 15"} (J2000)
ROLL:            310.305d
IMG_START_DATE:  17512 TJD;   125 DOY;   16/05/04
IMG_START_TIME:  70336.23 SOD {19:32:16.23} UT,   98.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     484083152
X_OFFSET:        673 [pixels]
Y_OFFSET:        1111 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       833
Y_GRB_POS:       1271
BINNING_INDEX:   1
IM_URL:          sw00685124000msuni0115.fits
SUN_POSTN:        42.29d {+02h 49m 11s}  +16.26d {+16d 15' 48"}
SUN_DIST:         95.68 [deg]   Sun_angle= -8.5 [hr] (East of Sun)
MOON_POSTN:       16.22d {+01h 04m 53s}   +4.37d {+04d 22' 14"}
MOON_DIST:       116.06 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:      146.28, 56.78 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      142.75, 46.23 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        If you have elected to receive attachments:  
COMMENTS:        The uvot_catalog_image.fits.gz file does not exist; skipping the attachment.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 04 May 16 19:36:51 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     685124,   Seg_Num: 0
GRB_RA:          170.0732d {+11h 20m 17.56s} (J2000),
                 170.3055d {+11h 21m 13.32s} (current),
                 169.3586d {+11h 17m 26.06s} (1950)
GRB_DEC:         +55.9998d {+55d 59' 59.2"} (J2000),
                 +55.9102d {+55d 54' 36.5"} (current),
                 +56.2737d {+56d 16' 25.4"} (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:  17512 TJD;   125 DOY;   16/05/04
IMG_START_TIME:  70366.00 SOD {19:32:46.00} UT,   128.7 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:        42.29d {+02h 49m 11s}  +16.26d {+16d 15' 49"}
SUN_DIST:         95.71 [deg]   Sun_angle= -8.5 [hr] (East of Sun)
MOON_POSTN:       16.23d {+01h 04m 55s}   +4.37d {+04d 22' 26"}
MOON_DIST:       116.07 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:      146.24, 56.81 [deg] galactic lon,lat of the burst
ECL_COORDS:      142.79, 46.24 [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 Circular #19382
D. Malesani (DARK/NBI), J. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL), T. G. R. Roegiers (PSU), B. Sbarufatti (INAF-OAB/PSU) and T. N. Ukwatta (LANL) report on behalf of the Swift Team:
At 19:30:37 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 160504A (trigger=685124). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 170.043, +55.997 which is
```
   RA(J2000) = 11h 20m 10s
   Dec(J2000) = +55d 59' 48"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 10 sec. The peak count rate was ~1300 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 19:32:46.0 UT, 128.7 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 170.07309, 56.00016 which is equivalent to:
```
   RA(J2000)  = 11h 20m 17.54s
   Dec(J2000) = +56d 00' 00.6"
```
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This location is 61 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. We cannot determine whether the source is fading at the present time.
A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 8.12 x 10^19 cm^-2 (Willingale et al. 2013).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 98 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 0.01.
Burst Advocate for this burst is D. Malesani (malesani AT dark-cosmology.dk). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.)

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 04 May 16 19:58:10 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     685124,   Seg_Num: 0
POINT_RA:        170.005d {+11h 20m 01s} (J2000)
POINT_DEC:       +56.004d {+56d 00' 15"} (J2000)
POINT_ROLL:      310.301d
IMG_START_DATE:  17512 TJD;   125 DOY;   16/05/04
IMG_START_TIME:  70494.42 SOD {19:34:54.42} UT,   257.1 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.469
N_STARS:         35
X_OFFSET:        353 [pixels]
Y_OFFSET:        791 [pixels]
X_MAX:           1312 [pixels]
Y_MAX:           1750 [pixels]
DET_THRESH:      6
PHOTO_THRESH:    3
SL_URL:          sw00685124000msufc0257.fits
SUN_POSTN:        42.31d {+02h 49m 14s}  +16.27d {+16d 16' 04"}
SUN_DIST:         95.66 [deg]   Sun_angle= -8.5 [hr] (East of Sun)
MOON_POSTN:       16.44d {+01h 05m 46s}   +4.44d {+04d 26' 36"}
MOON_DIST:       115.92 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:      146.29, 56.78 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      142.74, 46.23 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 04 May 16 19:58:27 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     685124,   Seg_Num: 0
POINT_RA:        170.005d {+11h 20m 01s} (J2000)
POINT_DEC:       +56.004d {+56d 00' 15"} (J2000)
POINT_ROLL:      310.301d
IMG_START_DATE:  17512 TJD;   125 DOY;   16/05/04
IMG_START_TIME:  70494.42 SOD {19:34:54.42} UT,   257.1 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.469
N_STARS:         35
X_OFFSET:        353 [pixels]
Y_OFFSET:        791 [pixels]
X_MAX:           1312 [pixels]
Y_MAX:           1750 [pixels]
DET_THRESH:      6
PHOTO_THRESH:    3
SL_URL:          sw00685124000msufc0257.fits
SUN_POSTN:        42.31d {+02h 49m 14s}  +16.27d {+16d 16' 04"}
SUN_DIST:         95.66 [deg]   Sun_angle= -8.5 [hr] (East of Sun)
MOON_POSTN:       16.45d {+01h 05m 47s}   +4.44d {+04d 26' 39"}
MOON_DIST:       115.92 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:      146.29, 56.78 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      142.74, 46.23 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 04 May 16 19:58:47 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     685124,   Seg_Num: 0
GRB_RA:          170.0724d {+11h 20m 17.37s} (J2000),
                 170.3047d {+11h 21m 13.13s} (current),
                 169.3578d {+11h 17m 25.87s} (1950)
GRB_DEC:         +56.0013d {+56d 00' 04.6"} (J2000),
                 +55.9117d {+55d 54' 41.9"} (current),
                 +56.2752d {+56d 16' 30.8"} (1950)
GRB_ERROR:       2.3 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  17512 TJD;   125 DOY;   16/05/04
IMG_START_TIME:  70366.00 SOD {19:32:46.00} UT,   128.7 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:        42.31d {+02h 49m 14s}  +16.27d {+16d 16' 04"}
SUN_DIST:         95.69 [deg]   Sun_angle= -8.5 [hr] (East of Sun)
MOON_POSTN:       16.45d {+01h 05m 48s}   +4.45d {+04d 26' 43"}
MOON_DIST:       115.94 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:      146.24, 56.81 [deg] galactic lon,lat of the burst
ECL_COORDS:      142.79, 46.24 [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:     Wed 04 May 16 19:59:19 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     685124,   Seg_Num: 0
POINT_RA:        170.005d {+11h 20m 01s} (J2000)
POINT_DEC:       +56.004d {+56d 00' 15"} (J2000)
ROLL:            310.301d
IMG_START_DATE:  17512 TJD;   125 DOY;   16/05/04
IMG_START_TIME:  70494.42 SOD {19:34:54.42} UT,   257.1 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     484083310
X_OFFSET:        673 [pixels]
Y_OFFSET:        1111 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       833
Y_GRB_POS:       1271
BINNING_INDEX:   1
IM_URL:          sw00685124000msuni0274.fits
SUN_POSTN:        42.31d {+02h 49m 14s}  +16.27d {+16d 16' 05"}
SUN_DIST:         95.66 [deg]   Sun_angle= -8.5 [hr] (East of Sun)
MOON_POSTN:       16.45d {+01h 05m 49s}   +4.45d {+04d 26' 49"}
MOON_DIST:       115.92 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:      146.29, 56.78 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      142.74, 46.23 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 04 May 16 19:59:36 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     685124,   Seg_Num: 0
POINT_RA:        170.005d {+11h 20m 01s} (J2000)
POINT_DEC:       +56.004d {+56d 00' 15"} (J2000)
ROLL:            310.301d
IMG_START_DATE:  17512 TJD;   125 DOY;   16/05/04
IMG_START_TIME:  70494.42 SOD {19:34:54.42} UT,   257.1 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     484083310
X_OFFSET:        673 [pixels]
Y_OFFSET:        1111 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       833
Y_GRB_POS:       1271
BINNING_INDEX:   1
IM_URL:          sw00685124000msuni0274.fits
SUN_POSTN:        42.31d {+02h 49m 14s}  +16.27d {+16d 16' 05"}
SUN_DIST:         95.66 [deg]   Sun_angle= -8.5 [hr] (East of Sun)
MOON_POSTN:       16.46d {+01h 05m 50s}   +4.45d {+04d 26' 53"}
MOON_DIST:       115.91 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:      146.29, 56.78 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      142.74, 46.23 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 04 May 16 20:00:24 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     685124,   Seg_Num: 0
POINT_RA:        170.005d {+11h 20m 01s} (J2000)
POINT_DEC:       +56.004d {+56d 00' 16"} (J2000)
POINT_ROLL:      310.301d
IMG_START_DATE:  17512 TJD;   125 DOY;   16/05/04
IMG_START_TIME:  71095.89 SOD {19:44:55.89} UT,   858.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        0.557
N_STARS:         25
X_OFFSET:        113 [pixels]
Y_OFFSET:        551 [pixels]
X_MAX:           1552 [pixels]
Y_MAX:           1990 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw00685124000msufc0858.fits
SUN_POSTN:        42.31d {+02h 49m 15s}  +16.27d {+16d 16' 05"}
SUN_DIST:         95.66 [deg]   Sun_angle= -8.5 [hr] (East of Sun)
MOON_POSTN:       16.46d {+01h 05m 52s}   +4.45d {+04d 27' 02"}
MOON_DIST:       115.91 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:      146.29, 56.78 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      142.74, 46.23 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 04 May 16 20:00:48 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     685124,   Seg_Num: 0
POINT_RA:        170.005d {+11h 20m 01s} (J2000)
POINT_DEC:       +56.004d {+56d 00' 16"} (J2000)
POINT_ROLL:      310.301d
IMG_START_DATE:  17512 TJD;   125 DOY;   16/05/04
IMG_START_TIME:  71095.89 SOD {19:44:55.89} UT,   858.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        0.557
N_STARS:         25
X_OFFSET:        113 [pixels]
Y_OFFSET:        551 [pixels]
X_MAX:           1552 [pixels]
Y_MAX:           1990 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw00685124000msufc0858.fits
SUN_POSTN:        42.31d {+02h 49m 15s}  +16.27d {+16d 16' 06"}
SUN_DIST:         95.66 [deg]   Sun_angle= -8.5 [hr] (East of Sun)
MOON_POSTN:       16.47d {+01h 05m 53s}   +4.45d {+04d 27' 07"}
MOON_DIST:       115.91 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:      146.29, 56.78 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      142.74, 46.23 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 04 May 16 20:01:57 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     685124,   Seg_Num: 0
POINT_RA:        170.005d {+11h 20m 01s} (J2000)
POINT_DEC:       +56.004d {+56d 00' 16"} (J2000)
ROLL:            310.301d
IMG_START_DATE:  17512 TJD;   125 DOY;   16/05/04
IMG_START_TIME:  71095.89 SOD {19:44:55.89} UT,   858.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     484083912
X_OFFSET:        672 [pixels]
Y_OFFSET:        1110 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       832
Y_GRB_POS:       1270
BINNING_INDEX:   1
IM_URL:          sw00685124000msuni0875.fits
SUN_POSTN:        42.31d {+02h 49m 15s}  +16.27d {+16d 16' 06"}
SUN_DIST:         95.66 [deg]   Sun_angle= -8.5 [hr] (East of Sun)
MOON_POSTN:       16.48d {+01h 05m 55s}   +4.46d {+04d 27' 20"}
MOON_DIST:       115.90 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:      146.29, 56.78 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      142.74, 46.23 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 04 May 16 20:02:06 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     685124,   Seg_Num: 0
POINT_RA:        170.005d {+11h 20m 01s} (J2000)
POINT_DEC:       +56.004d {+56d 00' 16"} (J2000)
ROLL:            310.301d
IMG_START_DATE:  17512 TJD;   125 DOY;   16/05/04
IMG_START_TIME:  71095.89 SOD {19:44:55.89} UT,   858.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     484083912
X_OFFSET:        672 [pixels]
Y_OFFSET:        1110 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       832
Y_GRB_POS:       1270
BINNING_INDEX:   1
IM_URL:          sw00685124000msuni0875.fits
SUN_POSTN:        42.31d {+02h 49m 15s}  +16.27d {+16d 16' 07"}
SUN_DIST:         95.66 [deg]   Sun_angle= -8.5 [hr] (East of Sun)
MOON_POSTN:       16.48d {+01h 05m 56s}   +4.46d {+04d 27' 22"}
MOON_DIST:       115.90 [deg]
MOON_ILLUM:      6 [%]
GAL_COORDS:      146.29, 56.78 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      142.74, 46.23 [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 #19383
Klotz A., Turpin D., Atteia J.L. (CNRS-OMP-IRAP), Boer, M., Laugier, R. (CNRS-ARTEMIS), Gendre B. (UVI - Etelman Obs.) report:
We imaged the field of GRB 160504A detected by SWIFT (trigger 685124) with the TAROT robotic telescope (D=25cm) located at the Calern observatory, France.
The observations started 57.1s after the GRB trigger (16.5s after the notice). The elevation of the field increased from 77 degrees above horizon and weather conditions were good but during twilight.
The first image is trailed with a duration of 60.0s (see the description in Klotz et al., 2006, A&A 451, L39). We do not detect any OT with a limiting magnitude of: t0+57.1s to t0+117.1s : R > 15.3
The second image is 30.0s exposure in tracking mode: t0+132.5s to t0+162.5s : R > 15.7
We co-added a series of exposures: t0+132.5s to t0+426.0s : R > 17.2
Magnitudes were estimated with the nearby USNO-B1 stars and are not corrected for galactic dust extinction.
GCN Circular #19385
T. Kruehler (MPE Garching), A. de Ugarte Postigo (IAA-CSIC and DARK/NBI), and T. Kuutma (NOT) report on behalf of a larger collaboration:
We observed the field of GRB 160504A (Malesani et al., GCN #19382) with the NOT equipped with ALFOSC. Imaging in the r, i and z-band filter started at 20:54:10 UT on 2016-05-04, 1.4 hr after the GRB trigger.
We detect no sources in the enhanced XRT error circle given at http://www.swift.ac.uk/sper/685124/.
Calibrating our images against magnitudes from field stars of the SDSS catalog, we measure preliminary upper limits of
```
r > 23.3 mag
i > 22.8 mag
z > 22.0 mag
```
These limits are not corrected for the expected foreground extinction corresponding to a reddening of E(B-V) = 0.01 mag (Schlafly & Finkbeiner 2011).
GCN Circular #19386
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team.
Using 559 s of XRT Photon Counting mode data and 1 UVOT images for GRB 160504A, 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 = 170.07224, +56.00158 which is equivalent to:
```
RA (J2000): 11h 20m 17.34s
Dec (J2000): +56d 00' 05.7"
```
with an uncertainty of 1.9 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 #19387
L.M. McCauley (PSU), J.A. Kennea (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), S.L. Gibson (U. Leicester), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), A. Maselli (INAF-IASFPA), B. Sbarufatti (INAF-OAB/PSU) and D. Malesani report on behalf of the Swift-XRT team:
We have analysed 7.8 ks of XRT data for GRB 160504A (Malesani et al. GCN Circ. 19382), from 80 s to 18.1 ks after the BAT trigger. The data comprise 31 s in Windowed Timing (WT) mode (the first 7 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. 19386).
The light curve can be modelled with a series of power-law decays. The initial decay index is alpha=2.4 (+1.2, -3.4). At T+100 s the decay steepens to an alpha of 5.5 (+0.9, -0.7). The light curve breaks again at T+209 s to a decay with alpha=0.15 (+0.08, -0.65), before a final break at T+4742 s s after which the decay index is 0.68 (+0.15, -0.14).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.97 (+/-0.15). The best-fitting absorption column is 1.1 (+/-0.4) x 10^21 cm^-2, in excess of the Galactic value of 8.1 x 10^19 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.4 x 10^-11 (4.2 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     1.1 (+/-0.4) x 10^21 cm^-2
Galactic foreground: 8.1 x 10^19 cm^-2
Excess significance: 4.4 sigma
Photon index:	     1.97 (+/-0.15)
```
If the light curve continues to decay with a power-law decay index of 0.68, the count rate at T+24 hours will be 0.022 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 7.5 x 10^-13 (9.3 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/00685124.
This circular is an official product of the Swift-XRT team.
GCN Circular #19388
U.Quadri, L.Strabla and R.Girelli report:
We imaged the field of GRB 160504A detected by SWIFT(trigger 685124) with the robotic telescope of (IAU station 565) Bassano Bresciano Observatory, Italy. Member of: AAVSO - American Association of Variable Star Observers. ISSP - Italian Supernovae Search Project. UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili.
The observations started 22.45 min after the GRB trigger, with our Schmidt telescope D=320/400 mm F/D=3.1.
Weather conditions were good.
We co-added 2 series of 20 exposures of 120 sec each.
```
Start T0+      End T0+      Vlim
22.45 min    111.33 min     20
```
We did not found any optical counterpart in the error box of the XRTcandidate. (D. Malesani (DARK/NBI), J. A. Kennea (PSU)et al)
Magnitudes were estimated with the UCAC4 cat. and are not corrected for galactic dust extinction.
Reference: http://www.osservatoriobassano.org/GRB.asp
The message may be cited.
GCN Circular #19389
S. B. Cenko (NASA/GSFC), A. J. Levan (U. Warwick), N. R. Tanvir (U. Leicester), A. Cucchiara (STScI), and A. Fruchter (STScI) report on behalf of a larger collaboration:
We imaged the location of GRB160504A (Malesani et al., GCN 19382) with the Near Infrared Imager and Spectrometer (NIRI) on the 8 m Gemini North telescope beginning at 5:24 UT on 5 May 2016 (~ 9.9 hr after the Swift trigger). A total of 10 min of integration was obtained in each of the J, H, and K filters. Within the enhanced XRT localization (Goad et al., GCN 19386) we identify a single faint source at J2000.0 coordinates:
```
  RA: 11:20:17.18
  Dec: +56:00:04.7
```
Using a nearby point source from 2MASS for calibration, we calculate the following AB magnitudes for this object:
```
J = 23.6 +/- 0.4
H = 23.8 +/- 0.4
K = 23.3 +/- 0.2
```
Given the faintness of the object, we cannot determine at this time if it associated with GRB160504A.
GCN Circular #19390
M. H. Siegel (PSU) and D. Malesani (DARK/NBI) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 160504A 99 s after the BAT trigger (Malesani et al., GCN Circ. 19382). No optical afterglow consistent with the XRT position (Goad et al. GCN Circ. 19386) 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)             99          249          147         >20.8
white               99        11822         1316         >21.7
v                  587        16542         1317         >20.2
b                  513        10910         1145         >21.5
u (fc)                257          507          246         >20.4
u                  257         6616          678         >21.2
w1                 636         6411          432         >20.4
m2                4571        17443         1275         >21.0
w2                 735        12387          963         >21.7
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.01 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #19391
Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (GSFC/STScI), Eleonora Troja (GSFC), Owen Littlejohns (ASU), 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), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy (UMD) report:
We observed the field of GRB 160504A (Malesani, et al., GCN 19382) 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 2016/05 5.21 to 2016/05 5.36 UTC (19.64 to 23.11 hours after the BAT trigger), obtaining a total of 2.49 hours exposure in the r and i bands and 1.04 hours exposure in the Z, Y, J, and H bands.
For a source within the Swift-XRT error circle (Goad, et al., GCN 19386), in comparison with the SDSS DR9 and 2MASS catalogs, we obtain the following detection and upper limits (3-sigma):
```
 r > 23.70
 i = 23.62 +/- 0.36
 Z > 22.38
 Y > 22.08
 J > 21.73
 H > 21.35
```
These magnitudes, which appear to be consistent with those reported by Cenko et al., (GCN 19389), are in the AB system and are not corrected for Galactic extinction in the direction of the GRB.
We thank the staff of the Observatorio Astron=F3mico Nacional in San Pedro M=E1rtir.
GCN Circular #19393
D. M. Palmer (LANL), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), D. Malesani (DARK/NBI), C. B. Markwardt (GSFC), T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 160504A (trigger #685124) (Malesani, et al., GCN Circ. 19382). The BAT ground-calculated position is RA, Dec = 170.073, 56.002 deg which is
```
RA(J2000) = 11h 20m 17.5s
Dec(J2000) = +56d 00' 05.7"
```
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 88%.
The mask-weighted light curve shows that the main emission starts at T-40 sec, has a very broad profile, peaks near T+0 sec and ends by T+30 sec. T90 (15-350 keV) is 53.9 +- 6.0 sec (estimated error including systematics). We have concluded that a soft spike in the light curve of ~10 msec duration at T-135.5 sec is of instrumental and not astrophysical origin. Our analysis therefore excludes the time before T-135 sec.
The time-averaged spectrum from T-42.3 to T+16.2 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.88 +- 0.20. The fluence in the 15-150 keV band is 7.3 +- 0.9 x 10^-7erg/cm2. The 1-sec peak photon flux measured from T+0.51 sec in the 15-150 keV band is 0.7 +- 0.1 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/685124/BA/
GCN Circular #19510
K. P. Mooley, T. D. Staley, R. P. Fender (Oxford), G. E. Anderson (Curtin), T. Cantwell (Manchester), C. Rumsey, D. Titterington, S. Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, P. Scott (Cambridge), K. Grainge, A. Scaife (Manchester)
The AMI Large Array robotically triggered on the Swift alert for GRB 160504A (Malesani et al., GCN 19382) as part of the 4pisky program, and subsequent follow up observations were obtained up to 10 days post-burst. Our observations at 15 GHz on 2016 May 04.85, May 05.88, May 07.82, May 11.90, and May 14.90 (UT) do not reveal any radio source at the XRT location (Goad et al., GCN 19386), with 3sigma upper limits of 93 uJy, 72 uJy, 129 uJy, 123 uJy, and 120 uJy respectively.
We thank the AMI staff for scheduling these observations. The AMI-GRB database is a log of all GRB follow up observations with the AMI, and is available at http://4pisky.org/ami-grb/.

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Jochen Greiner, last update: 08-Jun-2016 [Disclaimer]