Gamma-ray Burst 180728A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 28 Jul 18 17:29:15 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     850471,   Seg_Num: 0
GRB_RA:          253.569d {+16h 54m 17s} (J2000),
                 253.944d {+16h 55m 47s} (current),
                 252.562d {+16h 50m 15s} (1950)
GRB_DEC:         -54.031d {-54d 01' 50"} (J2000),
                 -54.060d {-54d 03' 34"} (current),
                 -53.950d {-53d 56' 58"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       2308 [cnts]    Image_Peak=184 [image_cnts]
TRIGGER_DUR:     0.512 [sec] 
TRIGGER_INDEX:   70     E_range: 15-50 keV
BKG_INTEN:       23003 [cnts]
BKG_TIME:        62930.66 SOD {17:28:50.66} UT
BKG_DUR:         8 [sec]
GRB_DATE:        18327 TJD;   209 DOY;   18/07/28
GRB_TIME:        62940.71 SOD {17:29:00.71} UT
GRB_PHI:          15.40 [deg]
GRB_THETA:        35.84 [deg]
SOLN_STATUS:     0x20000003
RATE_SIGNIF:     19.64 [sigma]
IMAGE_SIGNIF:    10.51 [sigma]
MERIT_PARAMS:     +1  +0  +0  -1  +1  +0  +0  +1 +58  +0 
SUN_POSTN:       127.96d {+08h 31m 51s}  +18.87d {+18d 52' 10"}
SUN_DIST:        126.03 [deg]   Sun_angle= -8.4 [hr] (East of Sun)
MOON_POSTN:      317.96d {+21h 11m 49s}  -17.07d {-17d 04' 19"}
MOON_DIST:        61.08 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      333.97, -6.51 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      258.80,-31.23 [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:        This trigger occurred at longitude,latitude = 236.54,-20.50 [deg].  
COMMENTS:           
COMMENTS:        NOTE: This BAT event is temporally(2.0<100sec) coincident with the FERMI_GBM event (trignum=554491747).

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 28 Jul 18 17:29:26 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      44
TRIGGER_NUM:     554491747
GRB_RA:          240.917d {+16h 03m 40s} (J2000),
                 241.233d {+16h 04m 56s} (current),
                 240.067d {+16h 00m 16s} (1950)
GRB_DEC:         -40.850d {-40d 51' 00"} (J2000),
                 -40.900d {-40d 54' 00"} (current),
                 -40.713d {-40d 42' 45"} (1950)
GRB_ERROR:       21.72 [deg radius, statistical plus systematic]
GRB_INTEN:       72 [cnts/sec]
DATA_SIGNIF:     6.20 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        18327 TJD;   209 DOY;   18/07/28
GRB_TIME:        62942.28 SOD {17:29:02.28} UT
GRB_PHI:         262.00 [deg]
GRB_THETA:        50.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      6.45
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      38%  SGR_1806n20
2nd_MOST_LIKELY:  30%  GRB
DETECTORS:       0,0,0, 1,0,0, 0,1,0, 0,0,0, 0,0,
SUN_POSTN:       127.96d {+08h 31m 51s}  +18.87d {+18d 52' 10"}
SUN_DIST:        119.63 [deg]   Sun_angle= -7.6 [hr] (East of Sun)
MOON_POSTN:      317.96d {+21h 11m 50s}  -17.07d {-17d 04' 17"}
MOON_DIST:        69.01 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      337.63,  8.73 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      247.01,-19.70 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2018/bn180728728/quicklook/glg_lc_medres34_bn180728728.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 144.48,-21.90 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(2.0<100sec) coincident with the SWIFT_BAT event (trignum=850471).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 28 Jul 18 17:29:39 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      66
TRIGGER_NUM:     554491747
GRB_RA:          251.250d {+16h 45m 00s} (J2000),
                 251.599d {+16h 46m 24s} (current),
                 250.313d {+16h 41m 15s} (1950)
GRB_DEC:         -48.500d {-48d 30' 00"} (J2000),
                 -48.533d {-48d 31' 58"} (current),
                 -48.408d {-48d 24' 29"} (1950)
GRB_ERROR:       3.60 [deg radius, statistical plus systematic]
GRB_INTEN:       2903 [cnts/sec]
DATA_SIGNIF:     66.20 [sigma]
INTEG_TIME:      0.256 [sec]
GRB_DATE:        18327 TJD;   209 DOY;   18/07/28
GRB_TIME:        62942.28 SOD {17:29:02.28} UT
GRB_PHI:         258.00 [deg]
GRB_THETA:        40.00 [deg]
DATA_TIME_SCALE: 0.2560 [sec]
HARD_RATIO:      2.85
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      61%  GRB
2nd_MOST_LIKELY:  25%  Generic SGR
DETECTORS:       0,0,0, 1,0,0, 0,1,0, 0,0,0, 0,0,
SUN_POSTN:       127.96d {+08h 31m 51s}  +18.87d {+18d 52' 10"}
SUN_DIST:        126.12 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      317.96d {+21h 11m 50s}  -17.07d {-17d 04' 16"}
MOON_DIST:        61.72 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      337.31, -1.86 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      256.30,-25.95 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2018/bn180728728/quicklook/glg_lc_medres34_bn180728728.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 144.48,-21.90 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(2.0<100sec) coincident with the SWIFT_BAT event (trignum=850471).

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Sat 28 Jul 18 17:29:45 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      70
TRIGGER_NUM:     554491747
GRB_RA:          251.200d {+16h 44m 48s} (J2000),
                 251.549d {+16h 46m 12s} (current),
                 250.262d {+16h 41m 03s} (1950)
GRB_DEC:         -48.583d {-48d 34' 59"} (J2000),
                 -48.616d {-48d 36' 58"} (current),
                 -48.491d {-48d 29' 28"} (1950)
GRB_ERROR:       3.43 [deg radius, statistical plus systematic]
GRB_INTEN:       5261 [cnts/sec]
DATA_SIGNIF:     365.20 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        18327 TJD;   209 DOY;   18/07/28
GRB_TIME:        62942.28 SOD {17:29:02.28} UT
GRB_PHI:         258.00 [deg]
GRB_THETA:        40.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      2.20
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      67%  GRB
2nd_MOST_LIKELY:  20%  Generic SGR
DETECTORS:       0,0,0, 1,0,0, 0,1,0, 0,0,0, 0,0,
SUN_POSTN:       127.96d {+08h 31m 51s}  +18.87d {+18d 52' 10"}
SUN_DIST:        126.07 [deg]   Sun_angle= -8.2 [hr] (East of Sun)
MOON_POSTN:      317.96d {+21h 11m 50s}  -17.07d {-17d 04' 15"}
MOON_DIST:        61.76 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      337.22, -1.89 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      256.27,-26.04 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2018/bn180728728/quicklook/glg_lc_medres34_bn180728728.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 144.48,-21.90 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(2.0<100sec) coincident with the SWIFT_BAT event (trignum=850471).

GCN NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Sat 28 Jul 18 17:30:05 UT
NOTICE_TYPE:    INTEGRAL SPI ACS Trigger
TRIGGER_NUM:    8111,   Sub_Num: 0
GRB_INTEN:      9.40 [sigma]   
GRB_TIME:       62951.03 SOD {17:29:11.03} UT
GRB_DATE:       18327 TJD;   209 DOY;   18/07/28
COMMENTS:       INTEGRAL SPI_ACS GRB Trigger.
COMMENTS:       Time_Scale=2.0000 and Time_Error=1.0000. 
COMMENTS:
COMMENTS:       NOTE: This SPIACS event is temporally(9.0<100sec) coincident with the FERMI_GBM event (trignum=554491747).
COMMENTS:
COMMENTS:       The SPIACS lightcurve can be found at:
COMMENTS:       ftp://isdcarc.unige.ch/arc/FTP/ibas/spiacs/2018-07/2018-07-28T17-29-10.8592-08810-60304-0.lc

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 28 Jul 18 17:33:13 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     850471,   Seg_Num: 0
GRB_RA:          253.569d {+16h 54m 17s} (J2000),
                 253.944d {+16h 55m 47s} (current),
                 252.562d {+16h 50m 15s} (1950)
GRB_DEC:         -54.031d {-54d 01' 50"} (J2000),
                 -54.060d {-54d 03' 34"} (current),
                 -53.950d {-53d 56' 58"} (1950)
GRB_DATE:        18327 TJD;   209 DOY;   18/07/28
GRB_TIME:        62940.71 SOD {17:29:00.71} UT
TRIGGER_INDEX:   70
GRB_PHI:          15.40 [deg]
GRB_THETA:        35.84 [deg]
DELTA_TIME:      -44.00 [sec]
TRIGGER_DUR:     0.512 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     19.64 [sigma]
IMAGE_SIGNIF:    10.51 [sigma]
LC_URL:          sw00850471000msb.lc
SUN_POSTN:       127.96d {+08h 31m 51s}  +18.87d {+18d 52' 08"}
SUN_DIST:        126.03 [deg]   Sun_angle= -8.4 [hr] (East of Sun)
MOON_POSTN:      317.99d {+21h 11m 57s}  -17.07d {-17d 03' 54"}
MOON_DIST:        61.11 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      333.97, -6.51 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      258.80,-31.23 [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:        This trigger occurred at longitude,latitude = 236.54,-20.50 [deg].

GCN Circular #23046
R. L. C. Starling (U Leicester), S. D. Barthelmy (GSFC), A. Y. Lien (GSFC/UMBC), M. J. Moss (George Washington University), K. L. Page (U Leicester) and D. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift Observatory Team:
At 17:29:00 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 180728A (trigger=850471). Swift did not slew immediately due to the Earth limb constraint. The BAT on-board calculated location is RA, Dec 253.569, -54.031 which is
```
   RA(J2000) = 16h 54m 17s
   Dec(J2000) = -54d 01' 50"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a small precursor followed 10 seconds later by a bright FRED pulse of ~20 s duration. The peak count rate was ~100,000 counts/sec (15-350 keV), at ~13 sec after the trigger.
Due to an observing constraint, Swift will not slew until T0+23.6 minutes. There will be no XRT or UVOT data until this time.
Burst Advocate for this burst is R. L. C. Starling (rlcs1 AT star.le.ac.uk). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.)

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 28 Jul 18 17:58:31 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     850471,   Seg_Num: 0
GRB_RA:          253.5648d {+16h 54m 15.5s} (J2000),
                 253.9397d {+16h 55m 45.5s} (current),
                 252.5577d {+16h 50m 13.8s} (1950)
GRB_DEC:         -54.0437d {-54d 02' 37.3"} (J2000),
                 -54.0726d {-54d 04' 21.4"} (current),
                 -53.9626d {-53d 57' 45.3"} (1950)
GRB_ERROR:       5.8 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       37 [cnts]
IMG_START_DATE:  18327 TJD;   209 DOY;   18/07/28
IMG_START_TIME:  64671.51 SOD {17:57:51.51} UT,   1730.8 [sec] since BAT Trigger Time
CENTROID_X:      332.06,  raw= 332  [pixels]
CENTROID_Y:      387.86,  raw= 388  [pixels]
ROLL:            251.66 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   210.89
GRB_POS_XRT_Z:   60.50
IMAGE_URL:       sw00850471000msxps_rw.img
SUN_POSTN:       127.98d {+08h 31m 55s}  +18.86d {+18d 51' 53"}
SUN_DIST:        126.01 [deg]   Sun_angle= -8.4 [hr] (East of Sun)
MOON_POSTN:      318.20d {+21h 12m 49s}  -17.02d {-17d 01' 17"}
MOON_DIST:        61.27 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      333.96, -6.51 [deg] galactic lon,lat of the burst
ECL_COORDS:      258.80,-31.24 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 28 Jul 18 17:58:39 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     850471,   Seg_Num: 0
GRB_RA:          253.5648d {+16h 54m 15.5s} (J2000),
                 253.9397d {+16h 55m 45.5s} (current),
                 252.5577d {+16h 50m 13.8s} (1950)
GRB_DEC:         -54.0437d {-54d 02' 37.3"} (J2000),
                 -54.0726d {-54d 04' 21.4"} (current),
                 -53.9626d {-53d 57' 45.3"} (1950)
GRB_ERROR:       5.8 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       37 [cnts]
IMG_START_DATE:  18327 TJD;   209 DOY;   18/07/28
IMG_START_TIME:  64671.51 SOD {17:57:51.51} UT,   1730.8 [sec] since BAT Trigger Time
CENTROID_X:      332.06,  raw= 332  [pixels]
CENTROID_Y:      387.86,  raw= 388  [pixels]
ROLL:            251.66 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   210.89
GRB_POS_XRT_Z:   60.50
IMAGE_URL:       sw00850471000msxps_rw.img
SUN_POSTN:       127.98d {+08h 31m 55s}  +18.86d {+18d 51' 53"}
SUN_DIST:        126.01 [deg]   Sun_angle= -8.4 [hr] (East of Sun)
MOON_POSTN:      318.20d {+21h 12m 49s}  -17.02d {-17d 01' 17"}
MOON_DIST:        61.27 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      333.96, -6.51 [deg] galactic lon,lat of the burst
ECL_COORDS:      258.80,-31.24 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 28 Jul 18 17:58:21 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     850471,   Seg_Num: 0
GRB_RA:          253.5648d {+16h 54m 15.55s} (J2000),
                 253.9397d {+16h 55m 45.52s} (current),
                 252.5577d {+16h 50m 13.84s} (1950)
GRB_DEC:         -54.0437d {-54d 02' 37.3"} (J2000),
                 -54.0726d {-54d 04' 21.4"} (current),
                 -53.9626d {-53d 57' 45.3"} (1950)
GRB_ERROR:       5.8 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       7.92e-10 [erg/cm2/sec]
GRB_SIGNIF:      6.08 [sigma]
IMG_START_DATE:  18327 TJD;   209 DOY;   18/07/28
IMG_START_TIME:  64671.51 SOD {17:57:51.51} UT,   1730.8 [sec] since BAT Trigger Time
TAM[0-3]:        327.63 237.15 261.64 243.55
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       127.98d {+08h 31m 55s}  +18.86d {+18d 51' 53"}
SUN_DIST:        126.01 [deg]   Sun_angle= -8.4 [hr] (East of Sun)
MOON_POSTN:      318.20d {+21h 12m 48s}  -17.02d {-17d 01' 19"}
MOON_DIST:        61.27 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      333.96, -6.51 [deg] galactic lon,lat of the burst
ECL_COORDS:      258.80,-31.24 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 0.79 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 28 Jul 18 18:03:23 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     850471,   Seg_Num: 0
POINT_RA:        253.506d {+16h 54m 01s} (J2000)
POINT_DEC:       -53.994d {-53d 59' 37"} (J2000)
POINT_ROLL:      251.660d
IMG_START_DATE:  18327 TJD;   209 DOY;   18/07/28
IMG_START_TIME:  64681.12 SOD {17:58:01.12} UT,   1740.4 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        6.827
N_STARS:         190
X_OFFSET:        164 [pixels]
Y_OFFSET:        320 [pixels]
X_MAX:           1123 [pixels]
Y_MAX:           1279 [pixels]
DET_THRESH:      22
PHOTO_THRESH:    14
SL_URL:          sw00850471000msufc1740.fits
SUN_POSTN:       127.98d {+08h 31m 56s}  +18.86d {+18d 51' 50"}
SUN_DIST:        125.99 [deg]   Sun_angle= -8.4 [hr] (East of Sun)
MOON_POSTN:      318.24d {+21h 12m 59s}  -17.01d {-17d 00' 47"}
MOON_DIST:        61.33 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      333.97, -6.45 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      258.75,-31.20 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 28 Jul 18 18:03:44 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     850471,   Seg_Num: 0
POINT_RA:        253.506d {+16h 54m 01s} (J2000)
POINT_DEC:       -53.994d {-53d 59' 37"} (J2000)
POINT_ROLL:      251.660d
IMG_START_DATE:  18327 TJD;   209 DOY;   18/07/28
IMG_START_TIME:  64681.12 SOD {17:58:01.12} UT,   1740.4 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        6.827
N_STARS:         190
X_OFFSET:        164 [pixels]
Y_OFFSET:        320 [pixels]
X_MAX:           1123 [pixels]
Y_MAX:           1279 [pixels]
DET_THRESH:      22
PHOTO_THRESH:    14
SL_URL:          sw00850471000msufc1740.fits
SUN_POSTN:       127.98d {+08h 31m 56s}  +18.86d {+18d 51' 50"}
SUN_DIST:        125.99 [deg]   Sun_angle= -8.4 [hr] (East of Sun)
MOON_POSTN:      318.25d {+21h 12m 59s}  -17.01d {-17d 00' 45"}
MOON_DIST:        61.33 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      333.97, -6.45 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      258.75,-31.20 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 28 Jul 18 18:05:57 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     850471,   Seg_Num: 0
POINT_RA:        253.506d {+16h 54m 01s} (J2000)
POINT_DEC:       -53.994d {-53d 59' 37"} (J2000)
ROLL:            251.660d
IMG_START_DATE:  18327 TJD;   209 DOY;   18/07/28
IMG_START_TIME:  64681.12 SOD {17:58:01.12} UT,   1740.4 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     554493502
X_OFFSET:        484 [pixels]
Y_OFFSET:        546 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       644
Y_GRB_POS:       706
BINNING_INDEX:   1
IM_URL:          sw00850471000msuni1762.fits
SUN_POSTN:       127.99d {+08h 31m 57s}  +18.86d {+18d 51' 49"}
SUN_DIST:        125.98 [deg]   Sun_angle= -8.4 [hr] (East of Sun)
MOON_POSTN:      318.27d {+21h 13m 04s}  -17.01d {-17d 00' 31"}
MOON_DIST:        61.34 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      333.97, -6.45 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      258.75,-31.20 [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:     Sat 28 Jul 18 18:06:07 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     850471,   Seg_Num: 0
POINT_RA:        253.506d {+16h 54m 01s} (J2000)
POINT_DEC:       -53.994d {-53d 59' 37"} (J2000)
ROLL:            251.660d
IMG_START_DATE:  18327 TJD;   209 DOY;   18/07/28
IMG_START_TIME:  64681.12 SOD {17:58:01.12} UT,   1740.4 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     554493502
X_OFFSET:        484 [pixels]
Y_OFFSET:        546 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       644
Y_GRB_POS:       706
BINNING_INDEX:   1
IM_URL:          sw00850471000msuni1762.fits
SUN_POSTN:       127.99d {+08h 31m 57s}  +18.86d {+18d 51' 49"}
SUN_DIST:        125.98 [deg]   Sun_angle= -8.4 [hr] (East of Sun)
MOON_POSTN:      318.27d {+21h 13m 04s}  -17.01d {-17d 00' 30"}
MOON_DIST:        61.34 [deg]
MOON_ILLUM:      99 [%]
GAL_COORDS:      333.97, -6.45 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      258.75,-31.20 [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 Circular #23048
V. Lipunov, E. Gorbovskoy, N.Tiurina, D.Vlasenko, V.Kornilov, A.Kuznetsov, V.Chazov, I. Gorbunov, D.Zimnukhov, D.Kuvshinov, P.Balanutsa, V.Vladimirov, Lomonosov Moscow State University,SAI
D. Buckley, South African Astronomical Observatory (SAAO)
R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias (IAC)
A. Tlatov, V.Senik, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory
R. Podesta, F. Podesta, C. Lopez, C.Francile Observatorio Astronomico Felix Aguilar (OAFA)
H.Levato, Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)
O. Gres, N.M.Budnev , Yu.Ishmuhametova Irkutsk State University (ISU)
A. Gabovich, V. Yurkov, Yu. Sergienko Blagoveschensk Educational State University (BSPU)
MASTER-SAAO robotic telescope (MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the GRB180728A 22 sec after notice time and 38 sec after trigger time at 2018-07-28 17:29:38 UT in two polarizations. On our first (10s exposure) set we found new optical object (transient) within SWIFT error-box (ra=253.567 dec=-54.0308 r=0.05) :
MASTER OT J165415.75 -540239.27 RA, DEC = 16h 54m 15.75s , -54d 02m 39.27s m ~ 14.5
We see a surprising automatic light curve when the source has risen to constant magnitude during first ~30 minutes!
The observations made on zenit distance = 28 degrees, galaxy latitude b = -7 degree. The moon (99 % bright part) is 11 degrees above the horizon. The distance between moon and object is 61 The sun altitude is -19.8 degree. The object can be observed till 2018-07-29 05:17:09
The message may be cited.
GCN Circular #23049
M. Perri (ASDC), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), D.N. Burrows (PSU), J.A. Kennea (PSU) and G. Cusumano (INAF-IASF PA) report on behalf of the Swift-XRT team:
The XRT began observing the field of GRB 180728A at 17:57:51.5 UT, 1730.8 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 253.5648, -54.0437 which is equivalent to:
```
   RA(J2000)  = +16h 54m 15.55s
   Dec(J2000) = -54d 02' 37.3"
```
with an uncertainty of 5.8 arcseconds (radius, 90% containment). This location is 46 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy.
The initial flux in the 2.5 s image was 7.92e-10 erg cm^-2 s^-1 (0.2-10 keV).
GCN Circular #23050
V. Lipunov, E. Gorbovskoy, N.Tiurina, D.Vlasenko, V.Kornilov, A.Kuznetsov, V.Chazov, I. Gorbunov, D.Zimnukhov, D.Kuvshinov, P.Balanutsa, V.Vladimirov, Lomonosov Moscow State University,SAI
D. Buckley, South African Astronomical Observatory (SAAO)
R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias (IAC)
A. Tlatov, V.Senik, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory
R. Podesta, F. Podesta, C. Lopez, C.Francile Observatorio Astronomico Felix Aguilar (OAFA)
H.Levato, Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)
O. Gres, N.M.Budnev , Yu.Ishmuhametova Irkutsk State University (ISU)
A. Gabovich, V. Yurkov, Yu. Sergienko Blagoveschensk Educational State University (BSPU)
MASTER-SAAO robotic telescope (MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was detected new optical object (Lipunov et al., GCN Circ #23048) MASTER OT J165415.75-540239.27 at Swift XRT position (Starling et al., GCN #23046; Perri et al., GCN #23049;):
RA, DEC = 16h 54m 15.75s , -54d 02m 39.27s Error ~1 arcsec
We see a gradual attenuation of the OT on an automatic light curve. Thus, the transient is an optical counterpart of the gamma-ray burst GRB 180728A.
The automatic light curve is available at http://observ.pereplet.ru/images/MASTER_OT_J165415.75-540239.27.jpg
The message may be cited.
GCN Circular #23051
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team.
Using 1791 s of XRT Photon Counting mode data and 2 UVOT images for GRB 180728A, 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 = 253.56514, -54.04454 which is equivalent to:
```
RA (J2000): 16h 54m 15.63s
Dec (J2000): -54d 02' 40.3"
```
with an uncertainty of 1.5 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 #23052
A. Tohuvavohu (PSU), S. J. LaPorte (PSU), J.A. Kennea (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB) and R.L.C. Starling report on behalf of the Swift-XRT team:
We have analysed 7.2 ks of XRT data for GRB 180728A (Starling et al. GCN Circ. 23046), from 1.7 ks to 26.6 ks after the BAT trigger. The data comprise 1.9 ks in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN Circ. 23051).
The light curve can be modelled with a series of power-law decays. The initial decay index is alpha=0.56 (+/-0.05). At T+5559 s the decay steepens to an alpha of 1.49 (+0.29, -0.14) before breaking again at T+14.6 ks to a final decay with index alpha=0.58 (+0.23, -2.08).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.886 (+0.020, -0.017). The best-fitting absorption column is consistent with the Galactic value of 3.2 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.75 (+/-0.09) and a best-fitting absorption column of 3.8 (+/-0.5) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.5 x 10^-11 (6.2 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     3.8 (+/-0.5) x 10^21 cm^-2
Galactic foreground: 3.2 x 10^21 cm^-2
Excess significance: 2.2 sigma
Photon index:	     1.75 (+/-0.09)
```
If the light curve continues to decay with a power-law decay index of 0.58, the count rate at T+24 hours will be 0.65 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.0 x 10^-11 (4.0 x 10^-11) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00850471.
This circular is an official product of the Swift-XRT team.
GCN Circular #23053
P. Veres, C. Meegan, and B. Mailyan (all UAH) report on behalf of the Fermi GBM Team:
"At 17:29:02.28 UT on 28 July 2018, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 180728A (trigger 554491747 / 180728728) which was also detected by the Swift/BAT (Starling et al., GCN 23046). The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 35 degrees.
The GBM light curve consists of a precursor and a very bright peak with a duration (T90) of about 6.4 s (50-300 keV). The time-averaged spectrum from T0+9.2s to T0+23.6 s is best fit by a Band function with Epeak = 79.2 +/- 1.4 keV, alpha = -1.54 +/- 0.01, and beta = -2.46 +/- 0.02.
The event fluence (10-1000 keV) in this time interval is (5.65 +/- 0.02)E-5 erg/cm^2. The 1-sec peak photon flux measured starting from T0+11.1 s in the 10-1000 keV band is 231.0 +/- 1.2 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN Circular #23054
C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), R. L. C. Starling (U Leicester), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+667 sec from the recent telemetry downlink, we report further analysis of BAT GRB 180728A (trigger #850471) (Starling, et al., GCN Circ. 23046). The BAT ground-calculated position is RA, Dec = 253.574, -54.037 deg which is
```
    RA(J2000)  =  16h 54m 17.7s
    Dec(J2000) = -54d 02' 13.7"
```
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 57%.
The mask-weighted light curve shows a relatively faint, soft precursor near the trigger time, lasting about 3 seconds. This was followed by a single, much brighter pulse, which consisted of two overlapping peaks. This pulse began at T+11 sec, peaked at T+13 sec, and faded to background by T+40 sec. T90 (15-350 keV) is 8.68 +- 0.30 sec (estimated error including systematics).
The time-averaged spectrum from T-0.24 to T+36.51 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.97 +- 0.03. The fluence in the 15-150 keV band is 2.96 +- 0.06 x 10^-5 erg/cm2. The 1-sec peak photon flux measured from T+12.61 sec in the 15-150 keV band is 132.0 +- 2.9 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/850471/BA/
GCN Circular #23055
A. Rossi (INAF-OAS), L. Izzo (HETH/IAA-CSIC), B. Milvang-Jensen (DAWN/NBI), D. A. Perley (LJMU), A. de Ugarte Postigo (HETH/IAA-CSIC and DARK/NBI), D. A. Kann (HETH/IAA-CSIC), A. J. Levan (U. Warwick), N. R. Tanvir (U. Leicester), S. Covino (INAF/Brera), and D. B. Malesani (DAWN/NBI and DARK/NBI) report on behalf of the Stargate collaboration:
We observed the optical counterpart of GRB 180728A (Starling et al., GCN 23046; Lipunov et al., GCN 23048) with the ESO VLT UT2 equipped with the X-shooter spectrograph. One 600 s spectrum was taken during evening twilight on 2018 July 28 beginning at 23:13 UT, plus two additional 600 s spectra on 2018 July 29 beginning at 05:10 UT. The spectra cover a wavelength range from 3000-25000 AA.
A red continuum is detected across the spectral range. We detect absorption features due to Mg II (3124,3132), Mg I (3187), and Ca II (4395,4434) at a consistent redshift of z=0.117, which we propose as the redshift of the GRB. Galactic ISM absorption features of Ca II and Na I are also detected.
This GRB resembles the famous GRB 030329, but slightly less energetic (E_iso = 2e+51 erg given the fluence value provided by Veres et al., GCN 23053). It is the closest energetic (E_iso > 1e+51 erg) GRB with a measured redshift to date.
We note that although Galactic extinction in this direction is significant (A_V = 0.763; Schlafly et al. 2011, ApJ 737:103) a campaign to study the anticipated associated supernova should still be practical with moderate-aperture telescopes at this redshift.
We acknowledge the ESO observing staff at Paranal, in particular Pascale Hibon and R. Thomas.
GCN Circular #23061
D. Frederiks, S. Golenetskii, R.Aptekar, A. Kozlova, A.Lysenko, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report:
The long, very bright GRB 180728A (Swift-BAT detection: Starling et al., GCN 23046; Fermi-GBM detection: Veres et al., GCN 23053) triggered Konus-Wind (KW) at T0=62954.093 s UT (17:29:14.093).
The burst light curve shows a smooth pulse with a total duration (T100) of ~17 s. The emission is seen up to ~10 MeV.
As observed by Konus-Wind, the burst had a fluence of (5.14 � 0.29)x10^-5 erg/cm2 and a 64-ms peak energy flux, measured from T0+15.168, of (1.94 � 0.15)x10^-5 erg/cm2 (both in the 20 keV - 10 MeV energy range).
The time-integrated spectrum (measured from T0 to T0+19.2 s) is best fit in the 30 keV - 15 MeV range by the GRB (Band) function with the following model parameters: the low-energy photon index alpha = -1.48 (-0.10,+0.12), the high energy photon index beta = -2.57 (-0.18,+0.12), the peak energy Ep = 97 (-6,+7) keV, chi2 = 94/96 dof.
The spectrum near the peak count rate (measured from T0+1.280 s to T0+1.792 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) function with the following model parameters: the low-energy photon index alpha = -1.44 (-0.15,+0.15), the high energy photon index beta = -2.81 (-1.44,+0.24), the peak energy Ep = 127 (-13,+18) keV, chi2 = 54/56 dof.
Assuming the redshift z=0.117 (Rossi et al., GCN 23055) and a standard cosmology with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315, and Omega_Lambda = 0.685 (Planck Collaboration, 2014), we estimate the following rest-frame parameters: the isotropic energy release E_iso is (2.33 � 0.10)x10^51 erg, the peak luminosity L_iso is (9.51 � 0.58)x10^50 erg/s (both in the 1-10000 keV rest-frame band). The rest-frame peak energy of the time-integrated spectrum, Epi,z, is 108(-7, 8) keV, and the rest-frame peak energy of the 'peak' spectrum, Epp,z, is 142(-15, 20) keV. With these energetics, the burst lies on the upper edges of 68% prediction bands for both 'Amati' and 'Yonetoku' relations built for the sample of 138 long KW GRBs with known redshifts (Tsvetkova et al., ApJ 850 161, 2017).
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB180728_T62954/
All the quoted errors are estimated at the 90% confidence level. All the presented results are preliminary.
GCN Circular #23064
GRB 180728A: Swift/UVOT Detection
S. J. LaPorte (PSU) and R. L. C. Starling (U. Leicester) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 180728A 1740 s after the BAT trigger (Starling et al., GCN Circ. 23046). A source consistent with the enhanced XRT position (Osborne et al. GCN Circ. 23051) is detected in the initial UVOT exposures.
The preliminary UVOT position is:
```
    RA  (J2000) =  16:54:15.53 =  253.56472 (deg.)
    Dec (J2000) = -54:02:40.2 =  -54.04451 (deg.)
```
with an estimated uncertainty of 0.43 arc sec. (radius, 90% confidence), consistent with MASTER OT J165415.75-540239.27 (Lipunov et al., GCN #23050).
Preliminary detections 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             1740         1890          147         16.25 +/- 0.03
white             7713         15148         465         17.28 +/- 0.03 
v                 1897         1917           20         16.07 +/- 0.14
b                 1995         2013           18         16.58 +/- 0.10
u                 1970         1990           20         15.93 +/- 0.10
w1                1946         1966           20         16.20 +/- 0.17
m2                1921         2114           39         16.60 +/- 0.18
w2                2045         2065           19         16.37 +/- 0.19
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.29 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #23066
FROM: Remo Rufinni at ICRA
R. Ruffini, Y. Aimuratov, C. L. Bianco, Y. C. Chen, D. M. Fuksman, M. Karlica, R. Moradi, D. Primorac, J.A. Rueda, N. Sahakyan, Y. Wang, on behalf of the ICRANet team, report:
GRB 180728A has T90=3D6.4s (P. Veres et al., GCN 23053), peak energy 142 (-15.+20) keV, and isotropic energy (2.33 +/- 0.10)x10^51 erg (D. Frederiks, et al., GCN 23061). It presents the typical characteristic of a subclass of long GRBs called X-ray flashes (XRFs, see Ruffini et al., ApJ 832 (2016) 136), originating from a tight binary of a FeCO Core undergoing a supernova explosion in presence of a companion neutron star (NS) which undergoes hypercritical accretion. The outcome (see Fig. [1]) is a new binary composed by a more massive NS (MNS) and a newly born NS (vNS). Using the averaged observed value (Cano et al., 2016), and considering the redshift z=3D0.117 (A. Rossi et al., GCN 23055), a bright optical signal will peak at 14.7 +/- 2.9 days after the trigger (12 August 2018, uncertainty from August 9th to August 15th) at the location of RA 253.56472 and DEC -54.04451, with an uncertainty 0.43 arc sec (S. J. LaPorte et al., GCN 23064). The follow-up observations, especially the optical bands for the SN, as well as attention to binary NS pulsar behaviors in the X-ray afterglow emission, are recommended.
[1] Link: http://www.icranet.org/documents/180728A_f1.png
Figure Caption: Snapshot of the binary system formed by the MNS and by the vNS together with the SN ejecta density. See for details Fig. 7 of Ruffini et al., ApJ 832 (2016) 136.
GCN Circular #23067
K. E. Heintz (Univ. Iceland and DAWN/NBI), L. Izzo (HETH/IAA-CSIC), A. Rossi (INAF-OAS), A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), D. B. Malesani (DAWN/NBI, DARK/NBI), D. A. Perley (LJMU), C. C. Thoene (HETH/IAA-CSIC), J. P. U. Fynbo (DAWN/NBI), B. Milvang-Jensen (DAWN/NBI), D. A. Kann (HETH/IAA-CSIC), N. R. Tanvir (U. Leicester), A. J. Levan (U. Warwick), S. Schulze (Weizmann), and G. Pugliese (API/U. Amsterdam) report on behalf of the Stargate collaboration;
We observed again the optical afterglow of the bright, low-redshift GRB 180728A (Starling et al., GCN 23046; Lipunov et al., GCB 23048; Rossi et al., GCB 23055) with the ESO VLT UT2 equipped with the X-shooter spectrograph. Observations were carried out around July 30.21 UT (35.5 hr after the GRB).
In our observations, the afterglow has faded significantly compared to our previous observation (Rossi et al., GCN 23055), reaching a magnitude of R ~ 20 (Vega). Continuum is detected across the whole observed range 3000-25000 AA, despite at lower S/N. Weak emission lines from a faint host are now visible, corresponding to Halpha, Hbeta, [N II], [O III] 5008 at the GRB redshift. The small Balmer decrement is consistent with negligible dust extinction in the host galaxy.
After excluding the host emission lines and correcting for Galactic extinction, the observed continuum can be fit with a single power-law with spectral index ~ 0.6 (F_nu~nu^-beta). In particular, we do not see evidence in any of our spectra for broad undulations or deviations from a power-law behavior as reported by Buckley et al. (ATel 11897). A figure showing our spectrum can be seen at: https://www.astro.ku.dk/~malesani/GRB/180728A/GRB180728A_spec.png
We acknowledge expert support from the ESO observing staff in Paranal, in particular Pascale Hibon, Bin Yang, and Romain Thomas.
GCN Circular #23102
V. Sharma and D. Bhattacharya (IUCAA), V. Bhalerao (IIT-B), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the Astrosat CZTI collaboration:
Analysis of Astrosat CZTI data showed the detection of a long GRB 180728A, which was also detected by Swift (Starling R. L. C. et al., GCN 23046), Fermi-GBM (Veres P. et al., GCN 23053) and Konus-Wind (Frederiks D. et al., GCN 23061).
The source was clearly detected in the 40-200 keV energy range. The light curve shows a single peak of emission with peak at 17:29:13.50 UT. The measured peak count rate is 1849.2 cts/s above the background in combined data of four quadrants, with a total of 6236 cts. The local mean background count rate was 650.8 cts/s. Using cumulative rates, we measure a T90 of 13.4 s.
It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range.
CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.
GCN Circular #23142
L. Izzo (HETH/IAA-CSIC), A. Rossi (INAF/OAS), D. B. Malesani (DAWN/NBI and DARK/NBI), K. E. Heintz (Univ. Iceland and DAWN/NBI), J. Selsing (DAWN/NBI), P. Schady (Univ. Bath), R. L. C. Starling (Univ. Leicester), J. Sollerman (OKC Stockholm), G. Leloudas (DTU space), Z. Cano (BCA), J. P. U. Fynbo (DAWN/NBI), M. Della Valle (INAF-Naples), E. Pian (INAF/OAS), D. A. Kann (HETH/IAA-CSIC), D. A. Perley (LJMU), E. Palazzi (INAF/OAS), S. Klose (TLS Tautenburg), J. Hjorth (DARK/NBI), S. Covino (INAF-OAB), V. D’Elia (SSDC), N. R. Tanvir (Univ. Leicester), A. J. Levan (Univ. Warwick), D. Hartmann (Clemson U.), C. Kouveliotou (GWU) report:
We report the results of continued photometric and spectroscopic follow-up of GRB 180728A at z = 0.117 (Starling et al., GCN 23046; Lipunov et al., GCN 23048; Rossi et al., GCN 23055; Heintz et al., GCN 23067) obtained with the X-shooter instrument on the ESO/VLT UT2, Chile.
Up to now, we have observed at three epochs, specifically at 6.27, 9.32 and 12.28 days after the GRB trigger. The optical counterpart is visible in all epochs using the X-shooter acquisition camera in the g, r and z filters. We report a rebrightening of 0.5 +- 0.1 mag in the r band between 6.27 and 12.28 days. This is consistent with what is observed in many other low-redshift GRBs, which in those cases is indicative of an emerging type Ic SN.
The spectra cover the wavelength range 3,000 - 21,000 AA. All the spectra have been corrected for the Galactic extinction (A_V = 0.92), while the host extinction is likely to be small, as indicated by our early-time spectra of the afterglow (Rossi et al., GCN 23055; Heintz et al., GCN 23067). The continuum shows a strong peak around 4500 AA (rest frame; 12.28 days after the GRB), but a black body is not a good fit, as the observed peak is too narrow. The peak shifts to longer wavelengths with time. Over the three epochs, significant features develop, including a broad absorption at ~7600 AA and a deep trough around 4900 AA (all rest frame), visible in our latest spectrum. However, over the covered epochs there is not much resemblance with other broad-lined SNe seen in previous low-redshift GRBs.
For the last spectrum, we attempted the identification of a few features. In particular, we identify the broad dip at 7600 AA as due to the blend O I 8446 AA and Ca II 8492 AA, at the expansion velocity of ~30,000 km s^-1. At this velocity, we also identify the Si II 6355 doublet, as well as C II 6580. The width of the lines spans several thousands km s^-1. Independent of the interpretation of the lines, the overall shape of the continuum, together with the presence of several absorption features a few thousands km s^-1 wide, strongly indicate that this is a SN. The lack of identified H and He in the spectra suggests a classification of type Ic.
A plot of the spectrum obtained at Day 12.28 compared with GRB 980425/SN 1998bw and XRF 100316D/SN 2010bh can be found at the following link :
http://www.astro.ku.dk/~malesani/GRB/180728A/Day12_vs_98bw_2010bh_flux.png
Further observations are planned for this event, which are possible thanks to ESO director's discretionary time allocated to our project (program 2101.D-5044, PI Rossi). Further observations of this GRB/SN, particularly at different wavelengths, are strongly encouraged.
We thank the ESO staff for their kind availability in executing our series of observations, in particular we want to thank Boris Haeussler, Emanuela Pompei, John Pritchard, Luca Sbordone, Marcela Espinoza, Nestor Jimenez, Rodrigo Palomino, Steffen Mieske, Stephane Brillant. We also thank Dilyar Barat (ANU) and Francesco D’Eugenio (Univ. Ghent) for kindly providing their telescope time to observe the GRB/SN during their visitor run at ESO/VLT.

GCN Circular #23143
V. Lipunov, E. Gorbovskoy, N.Tiurina, D.Vlasenko, V.Kornilov, A.Kuznetsov, V.Chazov, I. Gorbunov, D.Zimnukhov, D.Kuvshinov, P.Balanutsa,V.Vladimirov, Lomonosov Moscow State University,SAI
D. Buckley, South African Astronomical Observatory (SAAO)
R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias (IAC)
A. Tlatov, V.Senik, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory
R. Podesta, F. Podesta, C. Lopez, C.Francile Observatorio Astronomico Felix Aguilar (OAFA)
H.Levato, Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)
O. Gres, N.M.Budnev , Yu.Ishmuhametova Irkutsk State University (ISU)
A. Gabovich, V. Yurkov, Yu. Sergienko Blagoveschensk Educational State University (BSPU)
MASTER Global Robotic Net ( Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) inspected GRB 180728A (SwiftBAT GRB discovery : Starling et al. GCN 23046; MASTER optical counterpart discovery: Lipunov et al. GCN 23048;GCN23050; SwiftXRT: Perri et al. GCN 23049; Redshift, VLT: Rossi et al. GCN 23055; SN discovery,VLT: Izzo et al. GCN 23142). every night since the discovery.
There are unfiltered limits at MASTER images and absolute magnitude of SN ( Izzo et al. GCN 23142) for Omega_Vac = 0.7 and H_0 = 70 km/s/Mpc and Galactic extinction 0.1 for our red ccd:

Date_Time,UT            |   Exp,s | MASTER-Site |  m_lim| M

2018-07-29 21:18:37.092 |    2340 | MASTER-SAAO |  21.8 | -16.3
2018-07-30 21:07:24.839 |    1440 | MASTER-SAAO |  20.8 | -17.3
2018-07-30 21:07:24.912 |    1440 | MASTER-SAAO |  21.4 | -16.7
2018-08-01 19:11:32.906 |    1620 | MASTER-SAAO |  20.9 | -17.2
2018-08-01 19:15:07.977 |    1620 | MASTER-SAAO |  20.9 | -17.2
2018-08-02 17:03:40.025 |    3780 | MASTER-SAAO |  20.8 | -17.2
2018-08-02 18:12:49.446 |    3960 | MASTER-SAAO |  20.9 | -17.2
2018-08-03 17:53:21.097 |    4140 | MASTER-SAAO |  20.8 | -17.3
2018-08-03 17:53:21.347 |    4140 | MASTER-SAAO |  21.1 | -17.0
2018-08-03 23:21:10.842 |    3420 | MASTER-OAFA |  20.6 | -17.5
2018-08-04 17:05:35.120 |    2700 | MASTER-SAAO |  20.9 | -17.2
2018-08-04 17:12:46.879 |    2880 | MASTER-SAAO |  20.8 | -17.3
2018-08-04 23:07:09.154 |     720 | MASTER-OAFA |  20.5 | -17.6
2018-08-05 22:18:29.225 |    3240 | MASTER-SAAO |  20.8 | -17.3
2018-08-05 22:22:04.704 |    3240 | MASTER-SAAO |  21.1 | -17.0
2018-08-05 23:08:46.934 |    1260 | MASTER-OAFA |  21.5 | -16.5
2018-08-06 18:46:19.565 |    3600 | MASTER-SAAO |  20.8 | -17.3
2018-08-06 18:46:19.605 |    3600 | MASTER-SAAO |  20.8 | -17.3
2018-08-07 00:26:41.653 |     900 | MASTER-OAFA |  20.4 | -17.7
2018-08-07 03:30:36.096 |    2520 | MASTER-OAFA |  20.6 | -17.5
2018-08-07 17:15:34.447 |    3780 | MASTER-SAAO |  20.9 | -17.2
2018-08-07 18:23:07.857 |    3780 | MASTER-SAAO |  21.7 | -16.4
2018-08-08 17:59:05.042 |    4140 | MASTER-SAAO |  20.8 | -17.3
2018-08-08 18:02:42.597 |    4140 | MASTER-SAAO |  20.9 | -17.2
2018-08-08 23:11:34.904 |    3240 | MASTER-OAFA |  21.9 | -16.2
2018-08-09 18:55:17.807 |     540 | MASTER-SAAO |  20.8 | -17.2
2018-08-09 18:58:54.517 |     540 | MASTER-SAAO |  20.8 | -17.2
2018-08-09 23:04:26.723 |    3240 | MASTER-OAFA |  20.5 | -17.5
2018-08-10 17:00:41.943 |    2520 | MASTER-SAAO |  20.9 | -17.1
2018-08-11 00:08:05.570 |    4500 | MASTER-OAFA |  20.7 | -17.3
2018-08-11 18:43:29.720 |    7020 | MASTER-SAAO |  20.9 | -17.1
2018-08-11 23:12:32.140 |    3240 | MASTER-OAFA |  20.6 | -17.4
2018-08-12 19:46:57.192 |    7560 | MASTER-SAAO |  22.1 | -15.9
2018-08-12 19:46:57.246 |    7560 | MASTER-SAAO |  20.9 | -17.1
2018-08-12 23:18:02.053 |    3240 | MASTER-OAFA |  19.8 | -18.2
2018-08-13 07:43:55.504 |    3420 | MASTER-OAFA |  21.2 | -16.8

We have carried out preliminary photometry of MASTER early observations (Lipunov et al. GCN 23048; GCN23050;) also we report about considerable polarization of optical radiation of gamma burst the first minute after its beginning.
This message can be cited.

GCN Circular #23181
J. Selsing (DAWN/NBI), L. Izzo (HETH/IAA-CSIC), A. Rossi (INAF/OAS), D. B. Malesani (DAWN/NBI and DARK/NBI), K. E. Heintz (Univ. Iceland and DAWN/NBI), P. Schady (Univ. Bath), R. L. C. Starling (Univ. Leicester), J. Sollerman (OKC Stockholm), G. Leloudas (DTU space), Z. Cano (BCA), J. P. U. Fynbo (DAWN/NBI), M. Della Valle (INAF-Naples), E. Pian (INAF/OAS), D. A. Kann (HETH/IAA-CSIC), D. A. Perley (LJMU), E. Palazzi (INAF/OAS), S. Klose (TLS Tautenburg), J. Hjorth (DARK/NBI), S. Covino (INAF-OAB), V. D'Elia (SSDC), N. R. Tanvir (Univ. Leicester), A. J. Levan (Univ. Warwick), D. Hartmann (Clemson U.), and C. Kouveliotou (GWU) report on behalf of a larger collaboration:
We observed again the SN associated with GRB 180728A (Starling et al., GCN 23046; Izzo et al., GCN 23142) with the ESO VLT UT2 equipped with X-shooter. Observations had a mean epoch of 2018 August 21.078 UT (23.3 days after the GRB) and spanned the wavelength range 3200-20,900 AA.
The features previously observed in our spectroscopic sequence (Izzo et al., GCN 23142) have evolved and become more prominent. Using the Superfit tool (Howell et al. 2005, ApJ, 634, 1190; http://www.dahowell.com/superfit.html) we find a convincing match with the type-Ic SN 2002ap at a phase of 8 days after maximum. The timing is consistent with the epoch of our observation (21 days after the GRB after correcting for cosmic time dilation). We thus conclusively classify the SN as a broad-lined type-Ic SN. We note however that the velocity measured at this epoch (~10,000 km/s) is at the low end of what measured for GRB-associated SNe (e.g. Modjaz et al. 2016, 832, 108).
The SN associated to GRB 180728A has been dubbed SN 2018fip via the Transient Name Server: https://wis-tns.weizmann.ac.il/object/2018fip

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Jochen Greiner, last update: 28-Aug-2018 [Disclaimer]