Gamma-ray Burst 160525B

(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 25 May 16 09:25:32 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     687522,   Seg_Num: 0
GRB_RA:          149.443d {+09h 57m 46s} (J2000),
                 149.710d {+09h 58m 50s} (current),
                 148.624d {+09h 54m 30s} (1950)
GRB_DEC:         +51.180d {+51d 10' 49"} (J2000),
                 +51.101d {+51d 06' 05"} (current),
                 +51.419d {+51d 25' 08"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       1596 [cnts]    Image_Peak=94 [image_cnts]
TRIGGER_DUR:     0.512 [sec] 
TRIGGER_INDEX:   470     E_range: 25-100 keV
BKG_INTEN:       18539 [cnts]
BKG_TIME:        33895.68 SOD {09:24:55.68} UT
BKG_DUR:         8 [sec]
GRB_DATE:        17533 TJD;   146 DOY;   16/05/25
GRB_TIME:        33907.64 SOD {09:25:07.64} UT
GRB_PHI:         172.64 [deg]
GRB_THETA:        27.85 [deg]
SOLN_STATUS:     0x83
RATE_SIGNIF:     11.35 [sigma]
IMAGE_SIGNIF:    6.55 [sigma]
MERIT_PARAMS:     +1  +0  +0  -1  +2  -4  +0  +0 -31  +0 
SUN_POSTN:        62.64d {+04h 10m 34s}  +21.06d {+21d 03' 25"}
SUN_DIST:         71.97 [deg]   Sun_angle= -5.8 [hr] (East of Sun)
MOON_POSTN:      285.28d {+19h 01m 08s}  -18.13d {-18d 07' 44"}
MOON_DIST:       131.94 [deg]
MOON_ILLUM:      88 [%]
GAL_COORDS:      164.50, 49.51 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      131.87, 36.02 [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 = 57.23,18.37 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 25 May 16 09:26:38 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     687522,   Seg_Num: 0
POINT_RA:        149.426d {+09h 57m 42s} (J2000)
POINT_DEC:       +51.185d {+51d 11' 08"} (J2000)
IMG_START_DATE:  17533 TJD;   146 DOY;   16/05/25
IMG_START_TIME:  33991.00 SOD {09:26:31.00} UT,   83.4 [sec] since BAT Trigger Time
COUNTS:          4    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:     Wed 25 May 16 09:28:44 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     687522,   Seg_Num: 0
GRB_RA:          149.443d {+09h 57m 46s} (J2000),
                 149.710d {+09h 58m 50s} (current),
                 148.624d {+09h 54m 30s} (1950)
GRB_DEC:         +51.180d {+51d 10' 49"} (J2000),
                 +51.101d {+51d 06' 05"} (current),
                 +51.419d {+51d 25' 08"} (1950)
GRB_DATE:        17533 TJD;   146 DOY;   16/05/25
GRB_TIME:        33907.64 SOD {09:25:07.64} UT
TRIGGER_INDEX:   470
GRB_PHI:         172.64 [deg]
GRB_THETA:        27.85 [deg]
DELTA_TIME:      -75.00 [sec]
TRIGGER_DUR:     0.512 [sec] 
SOLN_STATUS:     0x83
RATE_SIGNIF:     11.35 [sigma]
IMAGE_SIGNIF:    6.55 [sigma]
LC_URL:          sw00687522000msb.lc
SUN_POSTN:        62.64d {+04h 10m 34s}  +21.06d {+21d 03' 26"}
SUN_DIST:         71.96 [deg]   Sun_angle= -5.8 [hr] (East of Sun)
MOON_POSTN:      285.31d {+19h 01m 15s}  -18.13d {-18d 07' 37"}
MOON_DIST:       131.95 [deg]
MOON_ILLUM:      88 [%]
GAL_COORDS:      164.50, 49.51 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      131.87, 36.02 [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 = 57.23,18.37 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 25 May 16 09:29:57 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     687522,   Seg_Num: 0
POINT_RA:        149.426d {+09h 57m 42s} (J2000)
POINT_DEC:       +51.186d {+51d 11' 09"} (J2000)
POINT_ROLL:      281.201d
IMG_START_DATE:  17533 TJD;   146 DOY;   16/05/25
IMG_START_TIME:  33995.71 SOD {09:26:35.71} UT,   88.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.206
N_STARS:         24
X_OFFSET:        384 [pixels]
Y_OFFSET:        558 [pixels]
X_MAX:           1343 [pixels]
Y_MAX:           1517 [pixels]
DET_THRESH:      17
PHOTO_THRESH:    10
SL_URL:          sw00687522000msufc0088.fits
SUN_POSTN:        62.64d {+04h 10m 35s}  +21.06d {+21d 03' 27"}
SUN_DIST:         71.95 [deg]   Sun_angle= -5.8 [hr] (East of Sun)
MOON_POSTN:      285.32d {+19h 01m 18s}  -18.13d {-18d 07' 34"}
MOON_DIST:       131.97 [deg]
MOON_ILLUM:      88 [%]
GAL_COORDS:      164.50, 49.50 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      131.85, 36.02 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 25 May 16 09:30:25 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     687522,   Seg_Num: 0
POINT_RA:        149.426d {+09h 57m 42s} (J2000)
POINT_DEC:       +51.186d {+51d 11' 09"} (J2000)
POINT_ROLL:      281.201d
IMG_START_DATE:  17533 TJD;   146 DOY;   16/05/25
IMG_START_TIME:  33995.71 SOD {09:26:35.71} UT,   88.1 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.206
N_STARS:         24
X_OFFSET:        384 [pixels]
Y_OFFSET:        558 [pixels]
X_MAX:           1343 [pixels]
Y_MAX:           1517 [pixels]
DET_THRESH:      17
PHOTO_THRESH:    10
SL_URL:          sw00687522000msufc0088.fits
SUN_POSTN:        62.64d {+04h 10m 35s}  +21.06d {+21d 03' 27"}
SUN_DIST:         71.95 [deg]   Sun_angle= -5.8 [hr] (East of Sun)
MOON_POSTN:      285.33d {+19h 01m 19s}  -18.13d {-18d 07' 33"}
MOON_DIST:       131.97 [deg]
MOON_ILLUM:      88 [%]
GAL_COORDS:      164.50, 49.50 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      131.85, 36.02 [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 25 May 16 09:30:27 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     687522,   Seg_Num: 0
GRB_RA:          149.3868d {+09h 57m 32.83s} (J2000),
                 149.6544d {+09h 58m 37.05s} (current),
                 148.5670d {+09h 54m 16.08s} (1950)
GRB_DEC:         +51.2065d {+51d 12' 23.3"} (J2000),
                 +51.1278d {+51d 07' 40.1"} (current),
                 +51.4451d {+51d 26' 42.3"} (1950)
GRB_ERROR:       3.7 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  17533 TJD;   146 DOY;   16/05/25
IMG_START_TIME:  33999.00 SOD {09:26:39.00} UT,   91.4 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:        62.64d {+04h 10m 35s}  +21.06d {+21d 03' 27"}
SUN_DIST:         71.92 [deg]   Sun_angle= -5.8 [hr] (East of Sun)
MOON_POSTN:      285.33d {+19h 01m 19s}  -18.13d {-18d 07' 33"}
MOON_DIST:       131.98 [deg]
MOON_ILLUM:      88 [%]
GAL_COORDS:      164.48, 49.47 [deg] galactic lon,lat of the burst
ECL_COORDS:      131.81, 36.03 [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:     Wed 25 May 16 09:31:48 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     687522,   Seg_Num: 0
POINT_RA:        149.426d {+09h 57m 42s} (J2000)
POINT_DEC:       +51.186d {+51d 11' 09"} (J2000)
ROLL:            281.201d
IMG_START_DATE:  17533 TJD;   146 DOY;   16/05/25
IMG_START_TIME:  33995.71 SOD {09:26:35.71} UT,   88.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     485861212
X_OFFSET:        703 [pixels]
Y_OFFSET:        877 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       863
Y_GRB_POS:       1037
BINNING_INDEX:   1
IM_URL:          sw00687522000msuni0105.fits
SUN_POSTN:        62.65d {+04h 10m 35s}  +21.06d {+21d 03' 28"}
SUN_DIST:         71.95 [deg]   Sun_angle= -5.8 [hr] (East of Sun)
MOON_POSTN:      285.34d {+19h 01m 22s}  -18.13d {-18d 07' 30"}
MOON_DIST:       131.98 [deg]
MOON_ILLUM:      88 [%]
GAL_COORDS:      164.50, 49.50 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      131.85, 36.02 [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).  
COMMENTS:        This notice was forced out after watchdog timer expiring -- most likely due to missing packet(s);  
COMMENTS:        as a consequence some of the fields may be incoorect (eg TRIGGER_NUM,RA,DEC).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 25 May 16 09:32:06 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     687522,   Seg_Num: 0
POINT_RA:        149.426d {+09h 57m 42s} (J2000)
POINT_DEC:       +51.186d {+51d 11' 09"} (J2000)
ROLL:            281.201d
IMG_START_DATE:  17533 TJD;   146 DOY;   16/05/25
IMG_START_TIME:  33995.71 SOD {09:26:35.71} UT,   88.1 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     485861212
X_OFFSET:        703 [pixels]
Y_OFFSET:        877 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       863
Y_GRB_POS:       1037
BINNING_INDEX:   1
IM_URL:          sw00687522000msuni0105.fits
SUN_POSTN:        62.65d {+04h 10m 35s}  +21.06d {+21d 03' 28"}
SUN_DIST:         71.95 [deg]   Sun_angle= -5.8 [hr] (East of Sun)
MOON_POSTN:      285.34d {+19h 01m 23s}  -18.13d {-18d 07' 30"}
MOON_DIST:       131.98 [deg]
MOON_ILLUM:      88 [%]
GAL_COORDS:      164.50, 49.50 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      131.85, 36.02 [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.  
COMMENTS:        This notice was forced out after watchdog timer expiring -- most likely due to missing packet(s);  
COMMENTS:        as a consequence some of the fields may be incoorect (eg TRIGGER_NUM,RA,DEC).

GCN Circular #19459
H. A. Krimm (CRESST/GSFC/USRA), S. D. Barthelmy (GSFC), A. D'Ai (INAF-IASFPA), P.A. Evans (U Leicester), C. Gronwall (PSU), F. E. Marshall (NASA/GSFC), A. Maselli (INAF-IASFPA), K. L. Page (U Leicester) and D. M. Palmer (LANL) report on behalf of the Swift Team:
At 09:25:07 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 160525B (trigger=687522). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 149.443, +51.180 which is
```
   RA(J2000)  =  09h 57m 46s
   Dec(J2000) = +51d 10' 49"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a single peak structure with a duration of about 10 sec. The peak count rate was ~1500 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 09:26:31.0 UT, 83.4 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 149.38688, 51.20658 which is equivalent to:
```
   RA(J2000)  = 09h 57m 32.85s
   Dec(J2000) = +51d 12' 23.7"
```
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This location is 158 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. No spectrum from the promptly downlinked event data is yet available to determine the column density.
UVOT took a finding chart exposure of 150 seconds with the White filter starting 88 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 H. A. Krimm (hans.krimm AT nasa.gov). 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 25 May 16 09:53:40 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     687522,   Seg_Num: 0
POINT_RA:        149.427d {+09h 57m 42s} (J2000)
POINT_DEC:       +51.188d {+51d 11' 17"} (J2000)
POINT_ROLL:      281.200d
IMG_START_DATE:  17533 TJD;   146 DOY;   16/05/25
IMG_START_TIME:  34207.61 SOD {09:30:07.61} UT,   300.0 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.307
N_STARS:         25
X_OFFSET:        144 [pixels]
Y_OFFSET:        318 [pixels]
X_MAX:           1583 [pixels]
Y_MAX:           1757 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00687522000msufc0299.fits
SUN_POSTN:        62.66d {+04h 10m 39s}  +21.06d {+21d 03' 37"}
SUN_DIST:         71.94 [deg]   Sun_angle= -5.8 [hr] (East of Sun)
MOON_POSTN:      285.54d {+19h 02m 10s}  -18.11d {-18d 06' 44"}
MOON_DIST:       132.08 [deg]
MOON_ILLUM:      88 [%]
GAL_COORDS:      164.50, 49.50 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      131.85, 36.02 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 25 May 16 09:53:55 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     687522,   Seg_Num: 0
POINT_RA:        149.427d {+09h 57m 42s} (J2000)
POINT_DEC:       +51.188d {+51d 11' 17"} (J2000)
POINT_ROLL:      281.200d
IMG_START_DATE:  17533 TJD;   146 DOY;   16/05/25
IMG_START_TIME:  34207.61 SOD {09:30:07.61} UT,   300.0 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.307
N_STARS:         25
X_OFFSET:        144 [pixels]
Y_OFFSET:        318 [pixels]
X_MAX:           1583 [pixels]
Y_MAX:           1757 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00687522000msufc0299.fits
SUN_POSTN:        62.66d {+04h 10m 39s}  +21.06d {+21d 03' 38"}
SUN_DIST:         71.94 [deg]   Sun_angle= -5.8 [hr] (East of Sun)
MOON_POSTN:      285.54d {+19h 02m 11s}  -18.11d {-18d 06' 44"}
MOON_DIST:       132.08 [deg]
MOON_ILLUM:      88 [%]
GAL_COORDS:      164.50, 49.50 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      131.85, 36.02 [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 25 May 16 09:54:05 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     687522,   Seg_Num: 0
GRB_RA:          149.3845d {+09h 57m 32.28s} (J2000),
                 149.6521d {+09h 58m 36.50s} (current),
                 148.5647d {+09h 54m 15.53s} (1950)
GRB_DEC:         +51.2064d {+51d 12' 23.0"} (J2000),
                 +51.1277d {+51d 07' 39.8"} (current),
                 +51.4450d {+51d 26' 41.9"} (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:  17533 TJD;   146 DOY;   16/05/25
IMG_START_TIME:  33999.00 SOD {09:26:39.00} UT,   91.4 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:        62.66d {+04h 10m 39s}  +21.06d {+21d 03' 38"}
SUN_DIST:         71.91 [deg]   Sun_angle= -5.8 [hr] (East of Sun)
MOON_POSTN:      285.55d {+19h 02m 11s}  -18.11d {-18d 06' 43"}
MOON_DIST:       132.09 [deg]
MOON_ILLUM:      88 [%]
GAL_COORDS:      164.48, 49.47 [deg] galactic lon,lat of the burst
ECL_COORDS:      131.81, 36.03 [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 25 May 16 09:55:01 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     687522,   Seg_Num: 0
POINT_RA:        149.427d {+09h 57m 42s} (J2000)
POINT_DEC:       +51.188d {+51d 11' 17"} (J2000)
ROLL:            281.200d
IMG_START_DATE:  17533 TJD;   146 DOY;   16/05/25
IMG_START_TIME:  34207.61 SOD {09:30:07.61} UT,   300.0 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     485861423
X_OFFSET:        703 [pixels]
Y_OFFSET:        877 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       863
Y_GRB_POS:       1037
BINNING_INDEX:   1
IM_URL:          sw00687522000msuni0316.fits
SUN_POSTN:        62.66d {+04h 10m 39s}  +21.06d {+21d 03' 38"}
SUN_DIST:         71.94 [deg]   Sun_angle= -5.8 [hr] (East of Sun)
MOON_POSTN:      285.55d {+19h 02m 13s}  -18.11d {-18d 06' 41"}
MOON_DIST:       132.08 [deg]
MOON_ILLUM:      88 [%]
GAL_COORDS:      164.50, 49.50 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      131.85, 36.02 [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 25 May 16 09:55:22 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     687522,   Seg_Num: 0
POINT_RA:        149.427d {+09h 57m 42s} (J2000)
POINT_DEC:       +51.188d {+51d 11' 17"} (J2000)
ROLL:            281.200d
IMG_START_DATE:  17533 TJD;   146 DOY;   16/05/25
IMG_START_TIME:  34207.61 SOD {09:30:07.61} UT,   300.0 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     485861423
X_OFFSET:        703 [pixels]
Y_OFFSET:        877 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       863
Y_GRB_POS:       1037
BINNING_INDEX:   1
IM_URL:          sw00687522000msuni0316.fits
SUN_POSTN:        62.66d {+04h 10m 39s}  +21.06d {+21d 03' 38"}
SUN_DIST:         71.94 [deg]   Sun_angle= -5.8 [hr] (East of Sun)
MOON_POSTN:      285.56d {+19h 02m 14s}  -18.11d {-18d 06' 41"}
MOON_DIST:       132.08 [deg]
MOON_ILLUM:      88 [%]
GAL_COORDS:      164.50, 49.50 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      131.85, 36.02 [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 #19460
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Using 1.9 ks of promptly downlinked XRT event data for GRB 160525B, we find an enhanced XRT position of the afterglow: RA, Dec: 149.3845, 51.2064 which is equivalent to:
```
   RA (J2000)  = 09 57 32.28
   Dec (J2000) = +51 12 23.0
```
with an uncertainty of 2.1 arcseconds (radius, 90% confidence). Analysis of the promptly available data is online at http://www.swift.ac.uk/sper/687522.
Position enhancement is is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177).
This circular is an official product of the Swift-XRT team.
GCN Circular #19463
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team.
Using 1923 s of XRT Photon Counting mode data and 2 UVOT images for GRB 160525B, 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 = 149.38464, +51.20657 which is equivalent to:
```
RA (J2000): 09h 57m 32.31s
Dec (J2000): +51d 12' 23.7"
```
with an uncertainty of 1.6 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 #19465
M. De Pasquale, N.P. Kuin (UCL-MSSL) and H. A. Krimm (CRESST/GSFC/USRA) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 160525B 88 s after the BAT trigger (Krimm et al., GCN Circ. 19459). A source consistent with the XRT position (Evans GCN Circ. 19460) is detected in the initial UVOT white filter exposure.
Preliminary detections and 3-sigma upper limits using the UVOT photometric 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               88          238          147         19.8 +/- 0.3
white              581         1894          284        >20.9
v                  631         1945          156        >18.9
b                  556         1870          136        >19.8
u                  300         2018          379        >20.0
w1                 680         1996          156        >19.5
m2                1603         1795           39        >18.2
w2                 606         1573           58        >18.9
```
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 #19466
D. Xu, Y.-H. Han (both NAOC/CAS), S.-G. Ma, A. Esamdin, J.-Z. Liu, L. Ma (all XAO) report:
We observed the field of GRB 160525B (Krimm et al., GCN 19459) using the 1m telescope located at Nanshan, Xinjiang, China. We obtained 5x300s R-band frames, starting at 15:26:24 UT on 2016-05-25, i.e., 6.02 hr after the burst.
No optical source is detected at the XRT position (Beardmore et al., GCN 19463) in the stacked image, down to a limiting magnitude of m(R)>21.5, calibrated with the nearby SDSS field.
GCN Circular #19467
V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), A. Maselli (INAF-IASFPA), L.M. McCauley (PSU), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), C. Pagani (U. Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester) and H.A. Krimm report on behalf of the Swift-XRT team:
We have analysed 6.3 ks of XRT data for GRB 160525B (Krimm et al. GCN Circ. 19459), from 91 s to 18.0 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN Circ. 19460).
The light curve can be modelled with a power-law decay with a decay index of alpha=1.27 (+/-0.10).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.91 (+0.26, -0.24). The best-fitting absorption column is 6.0 (+6.5, -5.1) x 10^20 cm^-2, consistent with the Galactic value of 8.3 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 (3.9 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     6.0 (+6.5, -5.1) x 10^20 cm^-2
Galactic foreground: 8.3 x 10^19 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.91 (+0.26, -0.24)
```
If the light curve continues to decay with a power-law decay index of 1.27, the count rate at T+24 hours will be 2.6 x 10^-4 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.8 x 10^-15 (10.0 x 10^-15) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00687522.
This circular is an official product of the Swift-XRT team.
GCN Circular #19468
S. D. Barthelmy (GSFC), 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), 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 160525B (trigger #687522) (Krimm, et al., GCN Circ. 19459). The BAT ground-calculated position is RA, Dec = 149.438, 51.197 deg, which is
```
   RA(J2000)  =  09h 57m 45.2s 
   Dec(J2000) = +51d 11' 48.9" 
```
with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 81%.
The mask-weighted light curve shows weak emission starting at ~T-1 sec, the main emission from ~T0 to ~T+0.3 sec, and weak emission out to ~T+0.6 sec. T90 (15-350 keV) is 0.29 +- 0.05 sec (estimated error including systematics).
The time-averaged spectrum from T+0.02 to T+0.33 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.89 +- 0.35. The fluence in the 15-150 keV band is 3.2 +- 0.8 x 10^-8 erg/cm2. The 1-sec peak photon flux measured from T-0.32 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/687522/BA/
GCN Circular #19469
E. Mazaeva (IKI), S. Schmalz (ISON), A. Volnova (IKI), N. Tungalag (Research Center of Astronomy and Geophysics MAS), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:
We observed the field of the GRB 160525B (Krimm et al., GCN 19459) with ORI-40 telescope of Khureltogot observatory starting on May, 25 (UT) 15:51:26. We do not detect any source within enhanced Swift-XRT position (Beardmore et al., GCN 19463). Preliminary photometry of the combined image is following
```
Date        UT start   t-T0    Filter  Exp.    UpperLimit (3 sigma)
                       (mid, days)      (s)

2016-05-25  15:51:26   0.29070  clear  60*60  21.0
```
Photometry is based on nearby SDSS-DR9 stars, Lupton transformations into R:
```
SDSS-DR9_id            R(Lupton)
J095742.79+511301.4    16.17
J095737.78+511402.4    16.43
J095736.76+511019.5    14.87
J095730.61+510914.1    17.74
J095737.35+510856.0    15.01
```
GCN Circular #19470
E. Mazaeva (IKI), E. Klunko (ISTP), A. Volnova (IKI), I. Korobtsev (ISTP), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:
We observed the field of the GRB 160525B (Krimm et al., GCN 19459) with AZT-33IK telescope of Sayan observatory (Mondy) starting on May, 25 (UT) 15:54:47. We do not detect any source within enhanced Swift-XRT position (Beardmore et al., GCN 19463). Preliminary photometry of the combined image is following
```
Date        UT start   t-T0    Filter  Exp.    UpperLimit (3 sigma)
                       (mid, days)      (s)

2016-05-25  15:54:47   0.29111  R       30*120  22.6
```
Photometry is based on nearby SDSS-DR9 stars, Lupton transformations into R:
```
SDSS-DR9_id            R(Lupton)
J095742.79+511301.4    16.17
J095737.78+511402.4    16.43
J095736.76+511019.5    14.87
J095730.61+510914.1    17.74
J095737.35+510856.0    15.01
```
GCN Circular #19475
K. Saisho, Y. Muraki, Y. Ono, T. Fujiwara, T. Yoshii, Y. Saito, Y. Tachibana, H. Ohuchi, Y. Yano, S. Harita, Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration:
We searched for the optical counterpart of GRB 160525B (H. A. Krimm et al., GCN Circular #19459) with the optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan.
The observation started on 2016-05-25 10:03:51 UT (~0.65 h after the burst). We did not find any new point source within XRT circle in all three bands.
We obtained following limits for the magnitudes.
```
T0+[hour]    MID-UT     T-EXP[sec]      g'         Rc          Ic
----------------------------------------------------------------------------
   0.65        15:58:53         1140       >18.6     >18.2    >17.6
----------------------------------------------------------------------------
T0+ : Elapsed time after the burst 
T-EXP: Total Exposure time 
```
We used GSC2.3 catalog for flux calibration.
GCN Circular #19564
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 160525B (Krimm et al., GCN 19459) 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 25.55, May 26.66, May 28.66, and May 31.68 (UT) do not reveal any radio source at the XRT location (Beardmore et al., GCN 19463), with 3sigma upper limits of 99 uJy, 63 uJy, 66 uJy, and 96 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/.
photometric redshift z = 0.64 +2.03 -0.14
of host-galaxy: A. E. Nugent et al. 2022, ApJ, 940, 57

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