Gamma-ray Burst 150728A

(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:     Tue 28 Jul 15 12:51:35 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     650617,   Seg_Num: 0
GRB_RA:          292.288d {+19h 29m 09s} (J2000),
                 292.433d {+19h 29m 44s} (current),
                 291.820d {+19h 27m 17s} (1950)
GRB_DEC:         +33.904d {+33d 54' 14"} (J2000),
                 +33.937d {+33d 56' 13"} (current),
                 +33.799d {+33d 47' 58"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       4136 [cnts]    Image_Peak=161 [image_cnts]
TRIGGER_DUR:     1.024 [sec] 
TRIGGER_INDEX:   438     E_range: 15-50 keV
BKG_INTEN:       28315 [cnts]
BKG_TIME:        46257.08 SOD {12:50:57.08} UT
BKG_DUR:         8 [sec]
GRB_DATE:        17231 TJD;   209 DOY;   15/07/28
GRB_TIME:        46271.03 SOD {12:51:11.03} UT
GRB_PHI:         -173.95 [deg]
GRB_THETA:        11.37 [deg]
SOLN_STATUS:     0x83
RATE_SIGNIF:     7.93 [sigma]
IMAGE_SIGNIF:    6.74 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +1  -3  +0  +1 +57  +0 
SUN_POSTN:       127.50d {+08h 30m 01s}  +18.98d {+18d 58' 43"}
SUN_DIST:        125.17 [deg]   Sun_angle= -11.0 [hr] (East of Sun)
MOON_POSTN:      266.35d {+17h 45m 24s}  -18.35d {-18d 20' 54"}
MOON_DIST:        57.89 [deg]
MOON_ILLUM:      89 [%]
GAL_COORDS:       67.23,  7.66 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      303.11, 54.81 [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 = 167.45,12.13 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 28 Jul 15 12:52:33 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     650617,   Seg_Num: 0
POINT_RA:        292.287d {+19h 29m 09s} (J2000)
POINT_DEC:       +33.909d {+33d 54' 31"} (J2000)
IMG_START_DATE:  17231 TJD;   209 DOY;   15/07/28
IMG_START_TIME:  46341.16 SOD {12:52:21.16} UT,   70.1 [sec] since BAT Trigger Time
COUNTS:          7    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        2    Max_iter_allowed= 4
ERROR_CODE:      1
COMMENTS:        SWIFT-XRT Nack Position.  
COMMENTS:        No source found in the image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 28 Jul 15 12:54:44 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     650617,   Seg_Num: 0
GRB_RA:          292.288d {+19h 29m 09s} (J2000),
                 292.433d {+19h 29m 44s} (current),
                 291.820d {+19h 27m 17s} (1950)
GRB_DEC:         +33.904d {+33d 54' 14"} (J2000),
                 +33.937d {+33d 56' 13"} (current),
                 +33.799d {+33d 47' 58"} (1950)
GRB_DATE:        17231 TJD;   209 DOY;   15/07/28
GRB_TIME:        46271.03 SOD {12:51:11.03} UT
TRIGGER_INDEX:   438
GRB_PHI:         -173.95 [deg]
GRB_THETA:        11.37 [deg]
DELTA_TIME:      45.00 [sec]
TRIGGER_DUR:     1.024 [sec] 
SOLN_STATUS:     0x83
RATE_SIGNIF:     7.93 [sigma]
IMAGE_SIGNIF:    6.74 [sigma]
LC_URL:          sw00650617000msb.lc
SUN_POSTN:       127.50d {+08h 30m 01s}  +18.98d {+18d 58' 41"}
SUN_DIST:        125.17 [deg]   Sun_angle= -11.0 [hr] (East of Sun)
MOON_POSTN:      266.38d {+17h 45m 32s}  -18.35d {-18d 20' 55"}
MOON_DIST:        57.88 [deg]
MOON_ILLUM:      89 [%]
GAL_COORDS:       67.23,  7.66 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      303.11, 54.81 [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 = 167.45,12.13 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 28 Jul 15 12:55:25 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     650617,   Seg_Num: 0
POINT_RA:        292.287d {+19h 29m 09s} (J2000)
POINT_DEC:       +33.909d {+33d 54' 31"} (J2000)
POINT_ROLL:      342.321d
IMG_START_DATE:  17231 TJD;   209 DOY;   15/07/28
IMG_START_TIME:  46346.32 SOD {12:52:26.32} UT,   75.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.518
N_STARS:         190
X_OFFSET:        439 [pixels]
Y_OFFSET:        549 [pixels]
X_MAX:           1398 [pixels]
Y_MAX:           1508 [pixels]
DET_THRESH:      13
PHOTO_THRESH:    7
SL_URL:          sw00650617000msufc0075.fits
SUN_POSTN:       127.50d {+08h 30m 01s}  +18.98d {+18d 58' 41"}
SUN_DIST:        125.17 [deg]   Sun_angle= -11.0 [hr] (East of Sun)
MOON_POSTN:      266.39d {+17h 45m 33s}  -18.35d {-18d 20' 56"}
MOON_DIST:        57.88 [deg]
MOON_ILLUM:      89 [%]
GAL_COORDS:       67.23,  7.67 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      303.11, 54.82 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 28 Jul 15 12:56:04 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     650617,   Seg_Num: 0
POINT_RA:        292.287d {+19h 29m 09s} (J2000)
POINT_DEC:       +33.909d {+33d 54' 31"} (J2000)
POINT_ROLL:      342.321d
IMG_START_DATE:  17231 TJD;   209 DOY;   15/07/28
IMG_START_TIME:  46346.32 SOD {12:52:26.32} UT,   75.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.518
N_STARS:         190
X_OFFSET:        439 [pixels]
Y_OFFSET:        549 [pixels]
X_MAX:           1398 [pixels]
Y_MAX:           1508 [pixels]
DET_THRESH:      13
PHOTO_THRESH:    7
SL_URL:          sw00650617000msufc0075.fits
SUN_POSTN:       127.51d {+08h 30m 01s}  +18.98d {+18d 58' 41"}
SUN_DIST:        125.17 [deg]   Sun_angle= -11.0 [hr] (East of Sun)
MOON_POSTN:      266.40d {+17h 45m 35s}  -18.35d {-18d 20' 56"}
MOON_DIST:        57.88 [deg]
MOON_ILLUM:      89 [%]
GAL_COORDS:       67.23,  7.67 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      303.11, 54.82 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 28 Jul 15 12:57:05 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     650617,   Seg_Num: 0
POINT_RA:        292.287d {+19h 29m 09s} (J2000)
POINT_DEC:       +33.909d {+33d 54' 31"} (J2000)
ROLL:            342.321d
IMG_START_DATE:  17231 TJD;   209 DOY;   15/07/28
IMG_START_TIME:  46346.32 SOD {12:52:26.32} UT,   75.3 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     459780761
X_OFFSET:        758 [pixels]
Y_OFFSET:        868 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       918
Y_GRB_POS:       1028
BINNING_INDEX:   1
IM_URL:          sw00650617000msuni0090.fits
SUN_POSTN:       127.51d {+08h 30m 01s}  +18.98d {+18d 58' 40"}
SUN_DIST:        125.17 [deg]   Sun_angle= -11.0 [hr] (East of Sun)
MOON_POSTN:      266.41d {+17h 45m 37s}  -18.35d {-18d 20' 57"}
MOON_DIST:        57.87 [deg]
MOON_ILLUM:      89 [%]
GAL_COORDS:       67.23,  7.67 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      303.11, 54.82 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 28 Jul 15 12:57:25 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     650617,   Seg_Num: 0
POINT_RA:        292.287d {+19h 29m 09s} (J2000)
POINT_DEC:       +33.909d {+33d 54' 31"} (J2000)
ROLL:            342.321d
IMG_START_DATE:  17231 TJD;   209 DOY;   15/07/28
IMG_START_TIME:  46346.32 SOD {12:52:26.32} UT,   75.3 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     459780761
X_OFFSET:        758 [pixels]
Y_OFFSET:        868 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       918
Y_GRB_POS:       1028
BINNING_INDEX:   1
IM_URL:          sw00650617000msuni0090.fits
SUN_POSTN:       127.51d {+08h 30m 02s}  +18.98d {+18d 58' 40"}
SUN_DIST:        125.17 [deg]   Sun_angle= -11.0 [hr] (East of Sun)
MOON_POSTN:      266.41d {+17h 45m 38s}  -18.35d {-18d 20' 57"}
MOON_DIST:        57.87 [deg]
MOON_ILLUM:      89 [%]
GAL_COORDS:       67.23,  7.67 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      303.11, 54.82 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 28 Jul 15 13:02:49 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     650617,   Seg_Num: 0
POINT_RA:        292.290d {+19h 29m 10s} (J2000)
POINT_DEC:       +33.909d {+33d 54' 32"} (J2000)
POINT_ROLL:      342.325d
IMG_START_DATE:  17231 TJD;   209 DOY;   15/07/28
IMG_START_TIME:  46558.49 SOD {12:55:58.49} UT,   287.5 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.817
N_STARS:         190
X_OFFSET:        199 [pixels]
Y_OFFSET:        309 [pixels]
X_MAX:           1638 [pixels]
Y_MAX:           1748 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    3
SL_URL:          sw00650617000msufc0287.fits
SUN_POSTN:       127.51d {+08h 30m 02s}  +18.98d {+18d 58' 37"}
SUN_DIST:        125.17 [deg]   Sun_angle= -11.0 [hr] (East of Sun)
MOON_POSTN:      266.46d {+17h 45m 51s}  -18.35d {-18d 21' 00"}
MOON_DIST:        57.85 [deg]
MOON_ILLUM:      89 [%]
GAL_COORDS:       67.23,  7.66 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      303.11, 54.82 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 28 Jul 15 13:03:11 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     650617,   Seg_Num: 0
POINT_RA:        292.290d {+19h 29m 10s} (J2000)
POINT_DEC:       +33.909d {+33d 54' 32"} (J2000)
POINT_ROLL:      342.325d
IMG_START_DATE:  17231 TJD;   209 DOY;   15/07/28
IMG_START_TIME:  46558.49 SOD {12:55:58.49} UT,   287.5 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.817
N_STARS:         190
X_OFFSET:        199 [pixels]
Y_OFFSET:        309 [pixels]
X_MAX:           1638 [pixels]
Y_MAX:           1748 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    3
SL_URL:          sw00650617000msufc0287.fits
SUN_POSTN:       127.51d {+08h 30m 02s}  +18.98d {+18d 58' 37"}
SUN_DIST:        125.17 [deg]   Sun_angle= -11.0 [hr] (East of Sun)
MOON_POSTN:      266.47d {+17h 45m 52s}  -18.35d {-18d 21' 00"}
MOON_DIST:        57.85 [deg]
MOON_ILLUM:      89 [%]
GAL_COORDS:       67.23,  7.66 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      303.11, 54.82 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 28 Jul 15 13:04:26 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     650617,   Seg_Num: 0
POINT_RA:        292.290d {+19h 29m 10s} (J2000)
POINT_DEC:       +33.909d {+33d 54' 32"} (J2000)
ROLL:            342.325d
IMG_START_DATE:  17231 TJD;   209 DOY;   15/07/28
IMG_START_TIME:  46558.49 SOD {12:55:58.49} UT,   287.5 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     459780973
X_OFFSET:        758 [pixels]
Y_OFFSET:        868 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       918
Y_GRB_POS:       1028
BINNING_INDEX:   1
IM_URL:          sw00650617000msuni0302.fits
SUN_POSTN:       127.51d {+08h 30m 03s}  +18.98d {+18d 58' 36"}
SUN_DIST:        125.17 [deg]   Sun_angle= -11.0 [hr] (East of Sun)
MOON_POSTN:      266.48d {+17h 45m 55s}  -18.35d {-18d 21' 01"}
MOON_DIST:        57.85 [deg]
MOON_ILLUM:      89 [%]
GAL_COORDS:       67.23,  7.66 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      303.11, 54.82 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 28 Jul 15 13:04:37 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     650617,   Seg_Num: 0
POINT_RA:        292.290d {+19h 29m 10s} (J2000)
POINT_DEC:       +33.909d {+33d 54' 32"} (J2000)
ROLL:            342.325d
IMG_START_DATE:  17231 TJD;   209 DOY;   15/07/28
IMG_START_TIME:  46558.49 SOD {12:55:58.49} UT,   287.5 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     459780973
X_OFFSET:        758 [pixels]
Y_OFFSET:        868 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       918
Y_GRB_POS:       1028
BINNING_INDEX:   1
IM_URL:          sw00650617000msuni0302.fits
SUN_POSTN:       127.51d {+08h 30m 03s}  +18.98d {+18d 58' 36"}
SUN_DIST:        125.17 [deg]   Sun_angle= -11.0 [hr] (East of Sun)
MOON_POSTN:      266.48d {+17h 45m 55s}  -18.35d {-18d 21' 01"}
MOON_DIST:        57.84 [deg]
MOON_ILLUM:      89 [%]
GAL_COORDS:       67.23,  7.66 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      303.11, 54.82 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 28 Jul 15 13:07:20 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     650617,   Seg_Num: 0
GRB_RA:          292.2269d {+19h 28m 54.45s} (J2000),
                 292.3724d {+19h 29m 29.38s} (current),
                 291.7596d {+19h 27m 02.30s} (1950)
GRB_DEC:         +33.9164d {+33d 54' 59.0"} (J2000),
                 +33.9493d {+33d 56' 57.4"} (current),
                 +33.8121d {+33d 48' 43.6"} (1950)
GRB_ERROR:       3.8 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  17231 TJD;   209 DOY;   15/07/28
IMG_START_TIME:  46355.00 SOD {12:52:35.00} UT,   84.0 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       127.51d {+08h 30m 03s}  +18.98d {+18d 58' 34"}
SUN_DIST:        125.14 [deg]   Sun_angle= -11.0 [hr] (East of Sun)
MOON_POSTN:      266.51d {+17h 46m 02s}  -18.35d {-18d 21' 02"}
MOON_DIST:        57.82 [deg]
MOON_ILLUM:      89 [%]
GAL_COORDS:       67.22,  7.71 [deg] galactic lon,lat of the burst
ECL_COORDS:      303.03, 54.84 [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:        This position was enhanced using UVOT field astrometry.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 2.8% < P(seren) < 6.6%.

GCN Circular #18087
H. A. Krimm (CRESST/GSFC/USRA), S. D. Barthelmy (GSFC), A. A. Breeveld (UCL-MSSL), D. N. Burrows (PSU), S. B. Cenko (GSFC), P. A. Evans (U Leicester), C. Gronwall (PSU), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester), P. Romano (INAF-IASFPA), T. Sakamoto (AGU), B. Sbarufatti (INAF-OAB/PSU) and M. H. Siegel (PSU) report on behalf of the Swift Team:
At 12:51:11 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 150728A (trigger=650617). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 292.288, +33.904 which is
```
   RA(J2000)  =  19h 29m 09s
   Dec(J2000) = +33d 54' 14"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows two weak peaks with a total duration of about 20 sec. The peak count rate was ~1000 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 12:52:21.1 UT, 70.2 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 292.2269, 33.9165 which is equivalent to:
```
   RA(J2000)  = 19h 28m 54.46s
   Dec(J2000) = +33d 54' 59.4"
```
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This location is 188 arcseconds from the BAT onboard position, outside 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 2.59 x 10^21 cm^-2 (Willingale et al. 2013).
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 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 0.20.
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:     Tue 28 Jul 15 13:19:52 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     650617,   Seg_Num: 0
POINT_RA:        292.290d {+19h 29m 10s} (J2000)
POINT_DEC:       +33.909d {+33d 54' 31"} (J2000)
POINT_ROLL:      342.325d
IMG_START_DATE:  17231 TJD;   209 DOY;   15/07/28
IMG_START_TIME:  47138.51 SOD {13:05:38.51} UT,   867.5 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.518
N_STARS:         190
X_OFFSET:        199 [pixels]
Y_OFFSET:        309 [pixels]
X_MAX:           1638 [pixels]
Y_MAX:           1748 [pixels]
DET_THRESH:      13
PHOTO_THRESH:    7
SL_URL:          sw00650617000msufc0867.fits
SUN_POSTN:       127.52d {+08h 30m 05s}  +18.97d {+18d 58' 27"}
SUN_DIST:        125.17 [deg]   Sun_angle= -11.0 [hr] (East of Sun)
MOON_POSTN:      266.63d {+17h 46m 32s}  -18.35d {-18d 21' 09"}
MOON_DIST:        57.79 [deg]
MOON_ILLUM:      89 [%]
GAL_COORDS:       67.23,  7.66 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      303.11, 54.81 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 28 Jul 15 13:20:10 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     650617,   Seg_Num: 0
POINT_RA:        292.290d {+19h 29m 10s} (J2000)
POINT_DEC:       +33.909d {+33d 54' 31"} (J2000)
POINT_ROLL:      342.325d
IMG_START_DATE:  17231 TJD;   209 DOY;   15/07/28
IMG_START_TIME:  47138.51 SOD {13:05:38.51} UT,   867.5 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.518
N_STARS:         190
X_OFFSET:        199 [pixels]
Y_OFFSET:        309 [pixels]
X_MAX:           1638 [pixels]
Y_MAX:           1748 [pixels]
DET_THRESH:      13
PHOTO_THRESH:    7
SL_URL:          sw00650617000msufc0867.fits
SUN_POSTN:       127.52d {+08h 30m 05s}  +18.97d {+18d 58' 27"}
SUN_DIST:        125.17 [deg]   Sun_angle= -11.0 [hr] (East of Sun)
MOON_POSTN:      266.63d {+17h 46m 32s}  -18.35d {-18d 21' 09"}
MOON_DIST:        57.78 [deg]
MOON_ILLUM:      89 [%]
GAL_COORDS:       67.23,  7.66 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      303.11, 54.81 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 28 Jul 15 13:21:35 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     650617,   Seg_Num: 0
POINT_RA:        292.290d {+19h 29m 10s} (J2000)
POINT_DEC:       +33.909d {+33d 54' 31"} (J2000)
ROLL:            342.325d
IMG_START_DATE:  17231 TJD;   209 DOY;   15/07/28
IMG_START_TIME:  47138.51 SOD {13:05:38.51} UT,   867.5 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     459781553
X_OFFSET:        758 [pixels]
Y_OFFSET:        868 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       918
Y_GRB_POS:       1028
BINNING_INDEX:   1
IM_URL:          sw00650617000msuni0882.fits
SUN_POSTN:       127.52d {+08h 30m 05s}  +18.97d {+18d 58' 26"}
SUN_DIST:        125.17 [deg]   Sun_angle= -11.0 [hr] (East of Sun)
MOON_POSTN:      266.65d {+17h 46m 36s}  -18.35d {-18d 21' 10"}
MOON_DIST:        57.78 [deg]
MOON_ILLUM:      89 [%]
GAL_COORDS:       67.23,  7.66 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      303.11, 54.81 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 28 Jul 15 13:21:50 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     650617,   Seg_Num: 0
POINT_RA:        292.290d {+19h 29m 10s} (J2000)
POINT_DEC:       +33.909d {+33d 54' 31"} (J2000)
ROLL:            342.325d
IMG_START_DATE:  17231 TJD;   209 DOY;   15/07/28
IMG_START_TIME:  47138.51 SOD {13:05:38.51} UT,   867.5 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     459781553
X_OFFSET:        758 [pixels]
Y_OFFSET:        868 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       918
Y_GRB_POS:       1028
BINNING_INDEX:   1
IM_URL:          sw00650617000msuni0882.fits
SUN_POSTN:       127.52d {+08h 30m 05s}  +18.97d {+18d 58' 26"}
SUN_DIST:        125.17 [deg]   Sun_angle= -11.0 [hr] (East of Sun)
MOON_POSTN:      266.65d {+17h 46m 36s}  -18.35d {-18d 21' 10"}
MOON_DIST:        57.78 [deg]
MOON_ILLUM:      89 [%]
GAL_COORDS:       67.23,  7.66 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      303.11, 54.81 [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 #18088
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team.
Using 1020 s of XRT Photon Counting mode data and 1 UVOT images for GRB 150728A, 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 = 292.22873, +33.91604 which is equivalent to:
```
RA (J2000): 19h 28m 54.89s
Dec (J2000): +33d 54' 57.7"
```
with an uncertainty of 4.0 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 #18090
S. Dichiara, C. Guidorzi (U. Ferrara), C.G. Mundell (U. Bath), S. Kobayashi (LJMU), A. Gomboc (U. Ljubljana) on behalf of a large collaboration report:
The 2-m Faulkes Telescope North began observing Swift GRB 150728A (Krimm et al. GCN 18087) on July 28, 13:48:25 UT (~57 minutes after the BAT trigger) with SDSS r and i filters.
we identify an uncatalogued object within XRT error circle (Beardmore et al. GCN 18088), at the following position:
```
RA(J2000) = 19:28:54.81
Dec(J2000)= +33:54:58.0
```
with an uncertainty of 1". The counterpart has the following magnitudes:
```
Mid time from  Total Exp   Filter    Magnitude
trigger (min)   (s)
-------------------------------------------------
61.8            120x5        r'     21.8 +- 0.3
73.3            120x5        i'     20.7 +- 0.3
-------------------------------------------------
```
Magnitudes are calibrated against nearby USNOB-1 stars (R2 and I). Presently we cannot state anything about possible variability in the source flux. However, we note that field is quite crowded.
GCN Circular #18091
T. N. Ukwatta (LANL), 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) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+946 sec from the recent telemetry downlinks, we report further analysis of BAT GRB 150728A (trigger #650617) (Krimm, et al., GCN Circ. 18087). The BAT ground-calculated position is RA, Dec = 292.271, 33.906 deg, which is
```
   RA(J2000)  =  19h 29m 05.1s 
   Dec(J2000) = +33d 54' 20.8" 
```
with an uncertainty of 2.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%.
The mask-weighted light curve shows a single spike starting at ~T_zero and ending at ~T+1.5 sec. T90 (15-350 keV) is 0.83 +- 0.23 sec (estimated error including systematics).
The time-averaged spectrum from T+0.24 to T+1.20 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.02 +- 0.48. The fluence in the 15-150 keV band is 3.3 +- 1.0 x 10^-8 erg/cm2. The 1-sec peak photon flux measured from T+0.22 sec in the 15-150 keV band is 0.5 +- 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/650617/BA/
GCN Circular #18092
A. A. Breeveld (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 150728A 75 s after the BAT trigger (Krimm et al., GCN Circ. 18087). No optical afterglow consistent with the XRT position (Beardmore et al. GCN Circ. 18088) or the Faulkes position (Dichiara et al. GCN Circ. 18090) 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            75          225          147         >21.3
u_FC               288          537          246         >20.4
white               75         6991          730         >22.0
v                  617         5982          275         >19.8
b                  543         6803          452         >21.1
u                  288         6597          678         >21.0
w1                 668         6392          452         >20.4
m2                 643         6187          452         >20.2
w2                 593         5777          255         >20.1
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.20 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #18093
C. Pagani (U. Leicester), A. Maselli (INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), T.G.R. Roegiers (PSU), 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 6.7 ks of XRT data for GRB 150728A (Krimm et al. GCN Circ. 18087), from 79 s to 30.0 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. 18088). The source is fading with alpha >0.4.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00650617.
This circular is an official product of the Swift-XRT team.
GCN Circular #18094
E. Mazaeva (IKI), R. Inasaridze (AAO), Sh. Makandarashvili (AAO), A. Volnova (IKI), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:
We observed the field of the Swift GRB 150728A (Krimm et al. GCN 18087) with AS-32 (0.7m) telescope of Abastumani Observatory starting on Jul. 28 (UT) 19:32:14. Within the enhanced XRT error circle (Beardmore et al. GCN 18088) we detected the object coinciding with the object found by FTN (Dichiara et al. GCN 18090). A photometry of the object is following
```
Date       UT start    t-T0     Filter  Exp.     OT
                        (mid, days)      (s)

2015-07-28 19:32:14    0.30491  None    28*120   20.6+/-0.25
```
The photometry is based on nearby USNO-B1.0 stars
```
USNO-B.1_id  R2
1239-0338943 17.06
1239-0338998 16.69
```
The photometry could be biased by nearby star. Presently we cannot say nothing about variability of the object and more observation is necessary to confirm/reject the object as afterglow of GRB 150728A.
GCN Circular #18096
Alan M. Watson (UNAM), Nat Butler (ASU), 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 (ORAU/GSFC), 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), and Harvey Moseley (GSFC) report:
We observed the field of GRB 150728A (Krimm et al., GCN 18087) with the=20 Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the= =20 1.5m Harold Johnson Telescope at the Observatorio Astron=F3mico Nacional = on=20 Sierra San Pedro M=E1rtir from 2015/07 29.19 to 2015/07 29.48 UTC (15.73 = to=20 22.75 hours after the BAT trigger), obtaining a total of 5.29 hours=20 exposure in the r, i, and z bands.
The brightest source within the enhanced Swift/XRT error circle (Beardmore et al., GCN 18088) is the cataloged source 2MASS 19285425+3354576, for=20 which we determine a position of 19:28:54.26 +33:54:57.6 (J2000, =B10.5") and magnitudes:
```
   r	16.71 =B1 0.02
   i	16.49 =B1 0.01
   z	16.14 =B1 0.04
```
We detect two other uncataloged sources on the edge of the error circle.=20 For source A we determine a position of 19:28:54.80 +33:54:58.2 (J2000,=20 =B10.5") and magnitudes:
```
   r     21.37 =B1 0.04
   i     20.89 =B1 0.04
   z     19.54 =B1 0.13
```
and for source B we determine 19:28:54.25 +33:55:2.6 (J2000, =B10.5") and:
```
   r     21.11 =B1 0.04
   i     20.73 =B1 0.03
   z     20.21 =B1 0.21
```
These magnitudes are in comparison with the USNO-B1 and 2MASS catalogs, are in the AB system, and are not corrected for Galactic extinction in the direction of the GRB.
Our source A appears to correspond to the source reported by Dichiara et=20 al. (GCN 18090). If this association is correct, then there is little=20 evidence for fading between about 1 hour and 16-23 hours.
We thank the staff of the Observatorio Astron=F3mico Nacional in San Pedro M=E1rtir.
GCN Circular #18097
E. Mazaeva (IKI), I. Reva (Fesenkov Astrophysical Institute), A. Volnova (IKI), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:
We observed the field of the Swift GRB 150728A (Krimm et al. GCN 18087) with Zeiss-1000 (East) 1-m telescope of Tien Shan Astronomical Observatory starting on Jul. 29 (UT) 18:34:50. We obtained several images in R-filter. In a combined image we do not detect the FTN object (Dichiara et al. GCN 18090) also visible in AAO observations (Mazaeva et al., GCN 18094) and source A in RATIR observations (Watson et al., GCN 18096). A photometry of the field is following
```
Date       UT start    t-T0     Filter  Exp.     ULimit (3sigma)
                        (mid, days)      (s)

2015-07-29 18:34:50    1.26425  R       15*300   21.2
```
The photometry is based on nearby USNO-B1.0 stars
```
USNO-B.1_id  R2
1239-0338943 17.06
1239-0338998 16.69
```
Also we marginally detect object B of the RATIR observations (Watson et al., GCN 18096) in our current and previous observation of the field (Mazaeva et al., GCN 18094).
The finding chart can be found in http://grb.rssi.ru/GRB150728A/GRB150728A_AAO_left_TSHAO_right.png
Would the source A be a non-variable point like object with magnitudes of r=21.37+/-0.04 and i=20.89+/-0.04 (Watson et al., GCN 18096) in our observation the object A might be detected as the object with a magnitude less than R=21.3 (3 sigma). So we tentatively suggest the object A as an afterglow candidate.
GCN Circular #18098
Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB)= ,=20 J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara=20 (ORAU/GSFC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico=20 Ramirez-Ruiz (UCSC), Jos=E9 A. de Diego (UNAM), Leonid Georgiev (UNAM),=20 Jes=FAs Gonz=E1lez (UNAM), Carlos Rom=E1n-Z=FA=F1iga (UNAM), Neil Gehrels= (GSFC),=20 and Harvey Moseley (GSFC) report:
We observed the field of GRB 150728A (Krimm et al., GCN 18087) with the=20 Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the= =20 1.5m Harold Johnson Telescope at the Observatorio Astron=F3mico Nacional = on=20 Sierra San Pedro M=E1rtir from 2015/07 31.22 to 2015/07 31.46 UTC (64.53 = to=20 70.24 hours after the BAT trigger), obtaining a total of 3.60 hours=20 exposure in the r, i, and z bands.
For source A of Watson et al. (GCN 18096), we determine:
```
   r	21.26 =B1 0.04
   i	20.90 =B1 0.04
   z	19.43 =B1 0.13
```
For source B of Watson et al. (GCN 18096), we determine:
```
   r	20.91 =B1 0.04
   i	20.70 =B1 0.04
   z	20.48 =B1 0.31
```
These magnitudes are in comparison with the USNO-B1 and 2MASS catalogs,=20 are in the AB system, and are not corrected for Galactic extinction in th= e=20 direction of the GRB.
Our source A appears to correspond to the source reported by Dichiara et=20 al. (GCN 18090). If this association is correct, then there is little=20 evidence for fading between observations at about 1 hour, 16-23 hours, an= d=20 65-70 hours. This is in contrast to the suggestion of Mazaeva et al. (GCN= =20 18097), who suggested that source A might indeed be the fading afterglow=20 on the basis of a 3-sigma non-detection at 30 hours.
Similarly, there is little evidence for fading of source B between 16-23=20 hours and 65-70 hours.
We thank the staff of the Observatorio Astron=F3mico Nacional in San Pedro M=E1rtir.
GCN Circular #18115
P. D'Avanzo, D. Fugazza (INAF/OABr), V. D'Elia (INAF/OAR and ASI/ASDC), V. Lorenzi, H. Stoev (INAF/TNG) report on behalf of the CIBO collaboration: We observed the field of the short GRB 150728A (Krimm et al., GCN 18087; Ukwatta et al. GCN 18091) with the 3.6m TNG telescope equipped with the DOLoRes camera. Observations consisted of 12 images in the r-sdss band for a total of 48 min exposure. The seeing was ~1.2".
No object is detected within the enhanced XRT position (Beardmore et al., GCN 18088), down to a limiting magnitude r > 24.5 (calibrated against nearby USNO-B1 stars). The mean time of the observation was 2015 Jul 30.9439 UT (2.41 days after the GRB). In particular, we find no evidence for fading for the object reported by Dichiara et al. in GCN 18090 (which appears to be point-like in our images), by measuring in our dataset a magnitute of r = 21.4 +/- 0.1 for this source (calibrated against nearby USNO-B1 stars).
Redshift z= 0.461 +- 0.0005 from host galaxy emission (Hbeta, [OIII], [OII])
W.-F. Fong et al. 2022, ApJ 940, 56

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