- GCN/BACODINE POSITION NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Fri 20 Jul 18 14:22:02 UT
NOTICE_TYPE: Swift-BAT GRB Position
TRIGGER_NUM: 848890, Seg_Num: 0
GRB_RA: 0.530d {+00h 02m 07s} (J2000),
0.767d {+00h 03m 04s} (current),
359.889d {+23h 59m 33s} (1950)
GRB_DEC: -2.933d {-02d 56' 00"} (J2000),
-2.830d {-02d 49' 47"} (current),
-3.212d {-03d 12' 41"} (1950)
GRB_ERROR: 3.00 [arcmin radius, statistical only]
GRB_INTEN: 9730 [cnts] Image_Peak=304 [image_cnts]
TRIGGER_DUR: 1.024 [sec]
TRIGGER_INDEX: 155 E_range: 50-350 keV
BKG_INTEN: 19469 [cnts]
BKG_TIME: 51690.70 SOD {14:21:30.70} UT
BKG_DUR: 8 [sec]
GRB_DATE: 18319 TJD; 201 DOY; 18/07/20
GRB_TIME: 51704.59 SOD {14:21:44.59} UT
GRB_PHI: 47.05 [deg]
GRB_THETA: 45.17 [deg]
SOLN_STATUS: 0x20000003
RATE_SIGNIF: 135.97 [sigma]
IMAGE_SIGNIF: 12.41 [sigma]
MERIT_PARAMS: +1 +0 +0 +0 +3 +2 +0 +0 +47 +0
SUN_POSTN: 119.92d {+07h 59m 40s} +20.59d {+20d 35' 34"}
SUN_DIST: 118.21 [deg] Sun_angle= 7.9 [hr] (West of Sun)
MOON_POSTN: 216.66d {+14h 26m 37s} -8.89d {-08d 53' 17"}
MOON_DIST: 142.36 [deg]
MOON_ILLUM: 58 [%]
GAL_COORDS: 94.83,-63.08 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 359.32, -2.90 [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 = 140.15,18.79 [deg].
COMMENTS:
COMMENTS: NOTE: This BAT event is temporally(5.0<100sec) coincident with the FERMI_GBM event (trignum=553789304).
- red DSS finding chart
ps-file
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Fri 20 Jul 18 14:22:06 UT
NOTICE_TYPE: Fermi-GBM Flight Position
RECORD_NUM: 47
TRIGGER_NUM: 553789304
GRB_RA: 25.483d {+01h 41m 56s} (J2000),
25.731d {+01h 42m 55s} (current),
24.816d {+01h 39m 16s} (1950)
GRB_DEC: +12.717d {+12d 43' 00"} (J2000),
+12.810d {+12d 48' 35"} (current),
+12.465d {+12d 27' 53"} (1950)
GRB_ERROR: 6.42 [deg radius, statistical plus systematic]
GRB_INTEN: 664 [cnts/sec]
DATA_SIGNIF: 16.70 [sigma]
INTEG_TIME: 0.256 [sec]
GRB_DATE: 18319 TJD; 201 DOY; 18/07/20
GRB_TIME: 51699.65 SOD {14:21:39.65} UT
GRB_PHI: 240.00 [deg]
GRB_THETA: 25.00 [deg]
DATA_TIME_SCALE: 0.2560 [sec]
HARD_RATIO: 0.70
LOC_ALGORITHM: 3 (version number of)
MOST_LIKELY: 95% GRB
2nd_MOST_LIKELY: 3% Generic Transient
DETECTORS: 0,0,0, 0,0,0, 0,1,0, 0,0,1, 0,0,
SUN_POSTN: 119.92d {+07h 59m 40s} +20.59d {+20d 35' 34"}
SUN_DIST: 89.35 [deg] Sun_angle= 6.3 [hr] (West of Sun)
MOON_POSTN: 216.66d {+14h 26m 37s} -8.89d {-08d 53' 18"}
MOON_DIST: 168.58 [deg]
MOON_ILLUM: 58 [%]
GAL_COORDS: 141.63,-48.31 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 28.22, 2.01 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2018/bn180720598/quicklook/glg_lc_medres34_bn180720598.gif
COMMENTS: Fermi-GBM Flight-calculated Coordinates.
COMMENTS: This trigger occurred at longitude,latitude = 213.97,-7.62 [deg].
COMMENTS: The LC_URL file will not be created until ~15 min after the trigger.
COMMENTS:
COMMENTS: NOTE: This GBM event is temporally(5.0<100sec) coincident with the SWIFT_BAT event (trignum=848890).
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Fri 20 Jul 18 14:22:13 UT
NOTICE_TYPE: Fermi-GBM Flight Position
RECORD_NUM: 58
TRIGGER_NUM: 553789304
GRB_RA: 25.750d {+01h 43m 00s} (J2000),
25.998d {+01h 43m 59s} (current),
25.083d {+01h 40m 20s} (1950)
GRB_DEC: +12.567d {+12d 34' 00"} (J2000),
+12.660d {+12d 39' 35"} (current),
+12.315d {+12d 18' 55"} (1950)
GRB_ERROR: 3.70 [deg radius, statistical plus systematic]
GRB_INTEN: 2295 [cnts/sec]
DATA_SIGNIF: 227.30 [sigma]
INTEG_TIME: 4.096 [sec]
GRB_DATE: 18319 TJD; 201 DOY; 18/07/20
GRB_TIME: 51699.65 SOD {14:21:39.65} UT
GRB_PHI: 240.00 [deg]
GRB_THETA: 25.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO: 0.65
LOC_ALGORITHM: 3 (version number of)
MOST_LIKELY: 96% GRB
2nd_MOST_LIKELY: 3% Generic Transient
DETECTORS: 0,0,0, 0,0,0, 0,1,0, 0,0,1, 0,0,
SUN_POSTN: 119.92d {+07h 59m 40s} +20.59d {+20d 35' 34"}
SUN_DIST: 89.16 [deg] Sun_angle= 6.3 [hr] (West of Sun)
MOON_POSTN: 216.66d {+14h 26m 38s} -8.89d {-08d 53' 19"}
MOON_DIST: 168.87 [deg]
MOON_ILLUM: 58 [%]
GAL_COORDS: 142.07,-48.38 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 28.41, 1.77 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2018/bn180720598/quicklook/glg_lc_medres34_bn180720598.gif
COMMENTS: Fermi-GBM Flight-calculated Coordinates.
COMMENTS: This trigger occurred at longitude,latitude = 213.97,-7.62 [deg].
COMMENTS: The LC_URL file will not be created until ~15 min after the trigger.
COMMENTS:
COMMENTS: NOTE: This GBM event is temporally(5.0<100sec) coincident with the SWIFT_BAT event (trignum=848890).
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Fri 20 Jul 18 14:22:24 UT
NOTICE_TYPE: Fermi-GBM Flight Position
RECORD_NUM: 70
TRIGGER_NUM: 553789304
GRB_RA: 26.050d {+01h 44m 12s} (J2000),
26.298d {+01h 45m 11s} (current),
25.383d {+01h 41m 32s} (1950)
GRB_DEC: +12.400d {+12d 24' 00"} (J2000),
+12.493d {+12d 29' 34"} (current),
+12.149d {+12d 08' 57"} (1950)
GRB_ERROR: 3.45 [deg radius, statistical plus systematic]
GRB_INTEN: 4652 [cnts/sec]
DATA_SIGNIF: 453.30 [sigma]
INTEG_TIME: 4.096 [sec]
GRB_DATE: 18319 TJD; 201 DOY; 18/07/20
GRB_TIME: 51699.65 SOD {14:21:39.65} UT
GRB_PHI: 240.00 [deg]
GRB_THETA: 25.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO: 0.68
LOC_ALGORITHM: 3 (version number of)
MOST_LIKELY: 96% GRB
2nd_MOST_LIKELY: 3% Generic Transient
DETECTORS: 0,0,0, 0,0,0, 0,1,0, 0,0,1, 0,0,
SUN_POSTN: 119.92d {+07h 59m 40s} +20.59d {+20d 35' 34"}
SUN_DIST: 88.94 [deg] Sun_angle= 6.2 [hr] (West of Sun)
MOON_POSTN: 216.66d {+14h 26m 38s} -8.89d {-08d 53' 21"}
MOON_DIST: 169.20 [deg]
MOON_ILLUM: 58 [%]
GAL_COORDS: 142.57,-48.45 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 28.63, 1.51 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2018/bn180720598/quicklook/glg_lc_medres34_bn180720598.gif
COMMENTS: Fermi-GBM Flight-calculated Coordinates.
COMMENTS: This trigger occurred at longitude,latitude = 213.97,-7.62 [deg].
COMMENTS: The LC_URL file will not be created until ~15 min after the trigger.
COMMENTS:
COMMENTS: NOTE: This GBM event is temporally(5.0<100sec) coincident with the SWIFT_BAT event (trignum=848890).
- GCN NOTICE
TITLE: GCN/INTEGRAL NOTICE
NOTICE_DATE: Fri 20 Jul 18 14:22:52 UT
NOTICE_TYPE: INTEGRAL SPI ACS Trigger
TRIGGER_NUM: 8110, Sub_Num: 0
GRB_INTEN: 10.50 [sigma]
GRB_TIME: 51700.98 SOD {14:21:40.98} UT
GRB_DATE: 18319 TJD; 201 DOY; 18/07/20
COMMENTS: INTEGRAL SPI_ACS GRB Trigger.
COMMENTS: Time_Scale=0.0500 and Time_Error=0.0250.
COMMENTS:
COMMENTS: NOTE: This SPIACS event is temporally(1.0<100sec) coincident with the FERMI_GBM event (trignum=553789304).
COMMENTS:
COMMENTS: The SPIACS lightcurve can be found at:
COMMENTS: ftp://isdcarc.unige.ch/arc/FTP/ibas/spiacs/2018-07/2018-07-20T14-21-40.7981-09794-52112-0.lc
- GCN NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Fri 20 Jul 18 14:23:46 UT
NOTICE_TYPE: Swift-XRT Processed Image
TRIGGER_NUM: 848890, Seg_Num: 0
GRB_RA: 0.5279d {+00h 02m 06.6s} (J2000),
0.7655d {+00h 03m 03.7s} (current),
359.8874d {+23h 59m 32.9s} (1950)
GRB_DEC: -2.9170d {-02d 55' 01.1"} (J2000),
-2.8137d {-02d 48' 49.4"} (current),
-3.1954d {-03d 11' 43.4"} (1950)
GRB_ERROR: 4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN: 81 [cnts]
IMG_START_DATE: 18319 TJD; 201 DOY; 18/07/20
IMG_START_TIME: 51791.05 SOD {14:23:11.05} UT, 86.5 [sec] since BAT Trigger Time
CENTROID_X: 316.98, raw= 317 [pixels]
CENTROID_Y: 310.01, raw= 310 [pixels]
ROLL: 68.13 [deg]
GAIN: 1
MODE: 2, Short Image mode
WAVEFORM: 134
EXPO_TIME: 0.10 [sec]
GRB_POS_XRT_Y: 27.38
GRB_POS_XRT_Z: 24.95
IMAGE_URL: sw00848890000msxps_rw.img
SUN_POSTN: 119.92d {+07h 59m 40s} +20.59d {+20d 35' 34"}
SUN_DIST: 118.21 [deg] Sun_angle= 7.9 [hr] (West of Sun)
MOON_POSTN: 216.67d {+14h 26m 41s} -8.89d {-08d 53' 35"}
MOON_DIST: 142.35 [deg]
MOON_ILLUM: 58 [%]
GAL_COORDS: 94.84,-63.07 [deg] galactic lon,lat of the burst
ECL_COORDS: 359.32, -2.89 [deg] ecliptic lon,lat of the burst
COMMENTS: SWIFT-XRT Processed Image.
- GCN NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Fri 20 Jul 18 14:23:44 UT
NOTICE_TYPE: Swift-XRT Image
TRIGGER_NUM: 848890, Seg_Num: 0
GRB_RA: 0.5279d {+00h 02m 06.6s} (J2000),
0.7655d {+00h 03m 03.7s} (current),
359.8874d {+23h 59m 32.9s} (1950)
GRB_DEC: -2.9170d {-02d 55' 01.1"} (J2000),
-2.8137d {-02d 48' 49.4"} (current),
-3.1954d {-03d 11' 43.4"} (1950)
GRB_ERROR: 4.7 [arcsec, radius, statistical plus systematic]
GRB_INTEN: 81 [cnts]
IMG_START_DATE: 18319 TJD; 201 DOY; 18/07/20
IMG_START_TIME: 51791.05 SOD {14:23:11.05} UT, 86.5 [sec] since BAT Trigger Time
CENTROID_X: 316.98, raw= 317 [pixels]
CENTROID_Y: 310.01, raw= 310 [pixels]
ROLL: 68.13 [deg]
GAIN: 1
MODE: 2, Short Image mode
WAVEFORM: 134
EXPO_TIME: 0.10 [sec]
GRB_POS_XRT_Y: 27.38
GRB_POS_XRT_Z: 24.95
IMAGE_URL: sw00848890000msxps_rw.img
SUN_POSTN: 119.92d {+07h 59m 40s} +20.59d {+20d 35' 34"}
SUN_DIST: 118.21 [deg] Sun_angle= 7.9 [hr] (West of Sun)
MOON_POSTN: 216.67d {+14h 26m 41s} -8.89d {-08d 53' 35"}
MOON_DIST: 142.35 [deg]
MOON_ILLUM: 58 [%]
GAL_COORDS: 94.84,-63.07 [deg] galactic lon,lat of the burst
ECL_COORDS: 359.32, -2.89 [deg] ecliptic lon,lat of the burst
COMMENTS: SWIFT-XRT Image.
- GCN NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Fri 20 Jul 18 14:23:35 UT
NOTICE_TYPE: Swift-XRT Position
TRIGGER_NUM: 848890, Seg_Num: 0
GRB_RA: 0.5279d {+00h 02m 06.69s} (J2000),
0.7655d {+00h 03m 03.72s} (current),
359.8874d {+23h 59m 32.98s} (1950)
GRB_DEC: -2.9170d {-02d 55' 01.1"} (J2000),
-2.8137d {-02d 48' 49.4"} (current),
-3.1954d {-03d 11' 43.4"} (1950)
GRB_ERROR: 5.0 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN: 6.59e-08 [erg/cm2/sec]
GRB_SIGNIF: 9.00 [sigma]
IMG_START_DATE: 18319 TJD; 201 DOY; 18/07/20
IMG_START_TIME: 51791.05 SOD {14:23:11.05} UT, 86.5 [sec] since BAT Trigger Time
TAM[0-3]: 327.67 237.20 261.71 243.48
AMPLIFIER: 2
WAVEFORM: 134
SUN_POSTN: 119.92d {+07h 59m 40s} +20.59d {+20d 35' 34"}
SUN_DIST: 118.21 [deg] Sun_angle= 7.9 [hr] (West of Sun)
MOON_POSTN: 216.67d {+14h 26m 40s} -8.89d {-08d 53' 33"}
MOON_DIST: 142.35 [deg]
MOON_ILLUM: 58 [%]
GAL_COORDS: 94.84,-63.07 [deg] galactic lon,lat of the burst
ECL_COORDS: 359.32, -2.89 [deg] ecliptic lon,lat of the burst
COMMENTS: SWIFT-XRT Coordinates.
COMMENTS: The XRT position is 0.98 arcmin from the BAT position.
- GCN NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Fri 20 Jul 18 14:25:34 UT
NOTICE_TYPE: Swift-BAT GRB Lightcurve
TRIGGER_NUM: 848890, Seg_Num: 0
GRB_RA: 0.530d {+00h 02m 07s} (J2000),
0.767d {+00h 03m 04s} (current),
359.889d {+23h 59m 33s} (1950)
GRB_DEC: -2.933d {-02d 56' 00"} (J2000),
-2.830d {-02d 49' 47"} (current),
-3.212d {-03d 12' 41"} (1950)
GRB_DATE: 18319 TJD; 201 DOY; 18/07/20
GRB_TIME: 51704.59 SOD {14:21:44.59} UT
TRIGGER_INDEX: 155
GRB_PHI: 47.05 [deg]
GRB_THETA: 45.17 [deg]
DELTA_TIME: 52.00 [sec]
TRIGGER_DUR: 1.024 [sec]
SOLN_STATUS: 0x3
RATE_SIGNIF: 135.97 [sigma]
IMAGE_SIGNIF: 12.41 [sigma]
LC_URL: sw00848890000msb.lc
SUN_POSTN: 119.92d {+07h 59m 40s} +20.59d {+20d 35' 33"}
SUN_DIST: 118.22 [deg] Sun_angle= 7.9 [hr] (West of Sun)
MOON_POSTN: 216.69d {+14h 26m 44s} -8.90d {-08d 53' 53"}
MOON_DIST: 142.33 [deg]
MOON_ILLUM: 58 [%]
GAL_COORDS: 94.83,-63.08 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 359.32, -2.90 [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 = 140.15,18.79 [deg].
- GCN Circular #22973
M. H. Siegel (PSU), D. N. Burrows (PSU), A. Deich (PSU),
J.D. Gropp (PSU), J. A. Kennea (PSU), S. J. LaPorte (PSU),
A. Y. Lien (GSFC/UMBC), M. J. Moss (George Washington University),
K. L. Page (U Leicester), D. M. Palmer (LANL), B. Sbarufatti (PSU) and
A. Tohuvavohu (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:
At 14:21:44 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180720B (trigger=848890). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 0.530, -2.933 which is
RA(J2000) = 00h 02m 07s
Dec(J2000) = -02d 56' 00"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a multi-peaked
structure with a duration of about 150 sec. The peak count rate
was ~50000 counts/sec (15-350 keV), at ~11 sec after the trigger.
The XRT began observing the field at 14:23:11.0 UT, 86.5 seconds after
the BAT trigger. XRT found a bright, flaring and fading uncatalogued
X-ray source located at RA, Dec 0.5279, -2.9170 which is equivalent to:
RA(J2000) = +00h 02m 6.70s
Dec(J2000) = -02d 55' 01.2"
with an uncertainty of 5.0 arcseconds (radius, 90% containment). This
location is 58 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 0.1 s image was 6.59e-08 erg cm^-2 s^-1 (0.2-10
keV).
No UVOT data is available yet.
Burst Advocate for this burst is M. H. Siegel (siegel AT swift.psu.edu).
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 Circular #22975
M. H. Siegel (PSU), D. N. Burrows (PSU), A. Deich (PSU),
J.D. Gropp (PSU), J. A. Kennea (PSU), S. J. LaPorte (PSU),
A. Y. Lien (GSFC/UMBC), M. J. Moss (George Washington University),
K. L. Page (U Leicester), D. M. Palmer (LANL), B. Sbarufatti (PSU) and
A. Tohuvavohu (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:
The GRB name in GCN Circ. #22973 should be GRB 180720B because of
an earlier detection of GRB 180720A from AGILE/MCAL (GCN Circ. #22970).
We apologize for the mistake and any confusion caused by this.
- GCN NOTICE
TITLE: GCN/MAXI NOTICE
NOTICE_DATE: Fri 20 Jul 18 14:56:17 UT
NOTICE_TYPE: MAXI Unknown Source Position
EVENT_ID_NUM: 319496378
EVENT_RA: 0.40d {+00h 01m 35s} (J2000),
0.63d {+00h 02m 32s} (current),
359.76d {+23h 59m 01s} (1950)
EVENT_DEC: -2.63d {-02d 37' 43"} (J2000),
-2.53d {-02d 31' 32"} (current),
-2.91d {-02d 54' 26"} (1950)
EVENT_ERROR: 1.0 [deg radius, stat+sys, 90% containment]
EVENT_FLUX: 406.0 +- 0.0 [mCrab]
EVENT_DATE: 18319 TJD; 201 DOY; 18/07/20
EVENT_TIME: 52109.00 SOD {14:28:29.00} UT
EVENT_TSCALE: 30s
EVENT_EBAND: Low, 2-4 keV
SUN_POSTN: 119.94d {+07h 59m 45s} +20.59d {+20d 35' 18"}
SUN_DIST: 118.25 [deg]
MOON_POSTN: 216.95d {+14h 27m 47s} -8.99d {-08d 59' 07"}
MOON_DIST: 142.02 [deg]
MOON_ILLUM: 59 [%]
GAL_COORDS: 94.84,-62.75 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 359.32, -2.57 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: MAXI Unknown Source Position. GRB or unknown X-ray Transient.
- GCN Circular #22976
R. Martone, C. Guidorzi (U. Ferrara), S. Kobayashi (LJMU), C.G. Mundell (U.
Bath), A. Gomboc (U. Nova Gorica), I.A. Steele (LJMU), A. Cucchiara, D. Morris
(U. of Virgin Islands) on behalf of a large collaboration report:
The LCO 2-m unit at Haleakala Observatory (Hawaii) began observing Swift
GRB180720B (Siegel et al. GCN 22973) on July 20, 14:33:34 UT (11.8 minutes
after the GRB trigger time) with the SDSS i' filter. On the border of the
Swift-XRT error circle, we detect a 13-mag uncatalogued object at the following
position:
RA(J2000)= +00:02:06.87
DEC(J2000)= -02:55:05.2
with an error radius of ~1�?? as calibrated against nearby SDSS stars.
- GCN Circular #22977
M. Sasada, T. Nakaoka, M. Kawabata, N. Uchida, Y. Yamazaki,
K. S. Kawabata (Hiroshima Univ.) report on behalf of Kanata team:
We performed optical and NIR imaging polarimetry to the field of the
GRB 180720B (Siegel et al. GCN 22973; Martone et al. GCN 22976) from
2018-07-20 14:22:57 UT (73 seconds after the trigger) with HOWPol
and HONIR attached to the 1.5-m Kanata telescope at Higashi-Hiroshima
Observatory, Japan. We detected a bright optical counterpart of the
GRB within the the Swift-XRT error circle of the X-ray afterglow. The
magnitude of the optical counterpart was R~9.4 mag in our first frame
taken with 30 second exposure and then smoothly declined. Further
analysis is ongoing.
- GCN NOTICE
TITLE: GCN/FERMI NOTICE
NOTICE_DATE: Fri 20 Jul 18 21:55:40 UT
NOTICE_TYPE: Fermi-LAT Offline Position
TRIGGER_NUM: 553789309
GRB_RA: 0.580d {+00h 02m 19s} (J2000),
0.818d {+00h 03m 16s} (current),
359.939d {+23h 59m 45s} (1950)
GRB_DEC: -2.950d {-02d 57' 00"} (J2000),
-2.847d {-02d 50' 47"} (current),
-3.228d {-03d 13' 41"} (1950)
GRB_ERROR: 6.60 [arcmin radius, 90% containment, statistical only]
GRB_DATE: 18319 TJD; 201 DOY; 18/07/20
GRB_TIME: 51704.54 SOD {14:21:44.54} UT
TRIGGER_ID: 0x30000000
MISC: 0x40000000
SUN_POSTN: 120.23d {+08h 00m 55s} +20.53d {+20d 31' 59"}
SUN_DIST: 118.47 [deg] Sun_angle= 8.0 [hr] (West of Sun)
MOON_POSTN: 220.50d {+14h 42m 01s} -10.15d {-10d 09' 01"}
MOON_DIST: 138.40 [deg]
MOON_ILLUM: 61 [%]
GAL_COORDS: 94.91,-63.12 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 359.36, -2.94 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: Fermi LAT Offline position.
COMMENTS: This Notice was ground-generated -- not flight-generated.
COMMENTS: It is the result of human-in-the-loop processing.
COMMENTS: This is a human generated position of a LAT ground detection.
COMMENTS: This source corresponds to GBM trigger.
- GCN Circular #22979
I. Reva (FAPHI), A. Pozanenko (IKI), A. Volnova (IKI), E. Mazaeva (IKI),
A. Kusakin (FAPHI), M. Krugov (FAPHI) report on behalf of larger GRB
follow-up collaboration:
We observed the field of GRB 180720B (Siegel et al., GCN 22973) with
Zeiss-1000 telescope of Tien Shan Astronomical Observatory starting on July
20 (UT) 19:46:17. We obtained several images in R and B-filters. The
optical afterglow (Martone et al. GCN 22976; Sasadaet al., GCN 22977) is
clearly detected in both filters. Preliminary photometry of the afterglow
at (UT, mid time) 19:59 is R =17.1 +/- 0.1. The photometry is based on
nearby USNO-B1.0 (R2) stars.
- GCN Circular #22981
O.J. Roberts (USRA/NASA) and C. Meegan (UAH) report on behalf
of the Fermi GBM Team:
"At 14:21:39.65 UT on 20 July 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180720B (trigger 553789304 / 180720598),
which was also detected by Swift (Siegel et al. 2018, GCN 22973/22975)
and the LAT (Bissaldi et al., GCN 22980). The GBM on-ground location is
consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time using the
Swift-XRT position is 50 degrees.
The GBM light curve consists of a very bright, FRED-like peak with
numerous overlapping pulses with a duration (T90) of 49 s (50-300 keV).
The time-averaged spectrum from T0 to T0+55 s is best fit by a Band
function with Epeak = 631 +/- 10 keV, alpha = -1.11 +/- 0.01 and
beta = -2.30 +/- 0.03.
The event fluence (10-1000 keV) over the T90 interval is
(2.985 +/- 0.001)E-04 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+4.4 s in the 10-1000 keV band is 125 +/- 1 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
- GCN Circular #22983
R. Itoh, K. L. Murata, Y. Tachibana, S. Harita, K. Morita,
K. Shiraishi, K. Iida, M. Oeda, R. Adachi, S. Niwano,
Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:
We observed the optical counterpart of GRB 180720B
(Siegel et al., GCN 22973)
with the optical three color (g', Rc, and Ic) CCD cameras attached to
the MITSuME 50cm telescope of Akeno Observatory, Yamanashi, Japan.
The observation started on 2018-07-20 18:08:46 UT, (~3.8 hours after
the burst). We detected the previously reported afterglow
(Martone et al., GCN 22976, Sasada et al., GCN 22977, Reva et al., GCN 22979)
in the g', Rc and Ic band.
The photometric results of the OT are listed below.
We used UCAC-4 catalog for flux calibration.
#T0+[hour] MID-UT T-EXP[sec] g' Rc Ic
-------------------------------------------------------------------
3.8 18:14:30 540 16.53+/-0.06 16.67+/-0.06 16.25+/- 0.08
-------------------------------------------------------------------
T0+ : Elapsed time after the burst [hour]
T-EXP: Total Exposure time [sec]
- GCN Circular #22984
K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), V. D'Elia
(ASDC), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), A. Tohuvavohu
(PSU), S. J. LaPorte (PSU), J.A. Kennea (PSU), P.A. Evans (U.
Leicester) and M.H. Siegel report on behalf of the Swift-XRT team:
We have analysed 7.2 ks of XRT data for GRB 180720B (Siegel et al. GCN
Circ. 22973), from 90 s to 19.4 ks after the BAT trigger. The data
comprise 3.3 ks in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The refined XRT position is RA, Dec =
0.5286, -2.9189 which is equivalent to:
RA (J2000): 00 02 06.86
Dec(J2000): -02 55 08.1
with an uncertainty of 3.5 arcsec (radius, 90% confidence).
The late-time light curve (from T0+5.6 ks) can be modelled with an
initial power-law decay with an index of alpha=1.18 (+0.16, -0.28),
followed by a break at T+7030 s to an alpha of -0.17 (+0.26, -1.33).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.770 (+/-0.011). The
best-fitting absorption column is 1.42 (+/-0.04) x 10^21 cm^-2, in
excess of the Galactic value of 3.9 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.85 (+/-0.07) and a
best-fitting absorption column of 1.75 (+0.23, -0.22) x 10^21 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum is 3.8 x 10^-11 (4.9 x 10^-11) erg cm^-2
count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 1.75 (+0.23, -0.22) x 10^21 cm^-2
Galactic foreground: 3.9 x 10^20 cm^-2
Excess significance: 10.1 sigma
Photon index: 1.85 (+/-0.07)
If the light curve continues to decay with a power-law decay index of
-0.17, the count rate at T+24 hours will be 21 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.4 x
10^-10 (1.1 x 10^-9) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00848890.
This circular is an official product of the Swift-XRT team.
- GCN Circular #22985
D. A. Kann, L. Izzo (both HETH/IAA-CSIC) and V. Casanova (IAA-CSIC)
report on behalf of HETH:
We observed the position of the extremely bright GRB 180720B (Swift-BAT
detection: Siegel et al., GCN #22973, GCN #22975; Fermi-LAT detection:
Bissaldi and Racusin, GCN #22980; Fermi-GBM detection: Roberts et al.,
GCN #22981) with the T90 telescope of the Observatorio Sierra Nevada
(OSN) near Granada, Spain.
The optical afterglow (Martone et al., GCN #22976; Sasada et al., GCN
#22977; Reva et al., GCN #22979; Itoh et al., GCN #22983) is clearly
detected in single 180 s images. For an Rc image at mid-time 0.455188
days after the INTEGRAL SPI/ACS trigger (14:21:40 UT), we derive Rc =
17.53 +/- 0.03 mag.
We note that this is only ~0.4 mag fainter than the value found by Reva
et al. at 0.23 days after the GRB, indicating the decay may have slowed
down. This feature also seems to be seen in the XRT light curve (Page et
al., GCN #22984).
Further observations, even with smaller telescopes, are strongly
encouraged.
Magnitudes were obtained against SDSS standard stars transformed
following the equations of Lupton (2005).
- GCN Circular #22986
P. A. Evans (U Leicester) reports on behalf of the Swift-XRT team :
The XRT refined analysis reported in GCN Circ. 22984 was the analysis of GRB 180720B, not A as reported in the circular. Apologies for the confusion.
- GCN Circular #22988
Nicolas Crouzet (IAC) and Daniele B. Malesani (DAWN/NBI and DARK/NBI)
report:
We observed the optical afterglow of GRB 180720B (Siegel et al., GCN
22973; Martone et al., GCN 22976) using the 0.4-m telescope located at
the Teide Observatory, part of the Las Cumbres Observatory (LCO)
telescope network.
A single 600-s exposure in the SDSS r band was obtained with mean time
July 21.094 UT (0.495 days after the GRB). The PSF of the image is not
optimal, being double-peaked.
Aperture photometry, compared to nearby stars from the Pan-STARRS
catalog, provides for the afterglow a preliminary magnitude r = 17.85 +-
0.10 AB.
- GCN Circular #22993
H. Negoro (Nihon U.), A. Tanimoto (Kyoto U.),
M. Nakajima, W. Maruyama, A. Sakamaki (Nihon U.),
T. Mihara, S. Nakahira, F. Yatabe, Y. Takao, M. Matsuoka (RIKEN),
N. Kawai, M. Sugizaki, Y. Tachibana, K. Morita (Tokyo Tech),
T. Sakamoto, M. Serino, S. Sugita, Y. Kawakubo, T. Hashimoto, A. Yoshida (AGU),
S. Ueno, H. Tomida, M. Ishikawa, Y. Sugawara, N. Isobe, R. Shimomukai (JAXA),
Y. Ueda, T. Morita, S. Yamada (Kyoto U.), Y. Tsuboi, W. Iwakiri, R. Sasaki,
H. Kawai, T. Sato (Chuo U.), H. Tsunemi, T. Yoneyama (Osaka U.),
M. Yamauchi, K. Hidaka, S. Iwahori (Miyazaki U.), T. Kawamuro (NAOJ),
K. Yamaoka (Nagoya U.), M. Shidatsu (Ehime U.)
report on behalf of the MAXI team:
The MAXI/GSC nova alert system triggered on GRB 180720B (Siegel et al., GCN 22973/20975;
Bissaldi et al., GCN 22980; Roberts et al., GCN 22981) at 14:28:15 UT on 2018 July 20,
396 sec after the Fermi/GRB trigger.
Assuming that the source flux was constant over the transit, we obtain the source position at
(R.A., Dec) = (0.467 deg, -2.846 deg) = (00 01 52, -02 50 45) (J2000)
with a statistical 90% C.L. elliptical error region
with long and short radii of 0.21 deg and 0.16 deg, respectively.
The roll angle of the long axis from the north direction is 166.0 deg counterclockwise.
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).
The above position is 5.6 arcminutes from the Swift/XRT
position of GRB 180720B (Siegel et al. GCN 22973).
The X-ray flux averaged over the scan was 191 +- 27 mCrab (4.0-10.0keV, 1 sigma error).
MAXI/GSC also detected the source at 25 +/- 12 mCrab in the next scan transit at 16:01.
The 2-20 keV GSC spectrum obtained in the scan transit at 14:28 is well described by
an absorbed power-law with a photon index of 2.11 +/- 0.25 with n_H fixed at the total
Galactic column density to the direction of 3.5e20 atoms/cm2.
- GCN Circular #22996
P. M. Vreeswijk (Radboud Univ. Nijmegen), D. A. Kann (HETH/IAA-CSIC), K.
E. Heintz (Univ. Iceland and DAWN/NBI), A. de Ugarte Postigo
(HETH-IAA/CSIC and DARK/NBI), B. Milvang-Jensen (DAWN/NBI), D. B.
Malesani (DARK/NBI and DAWN/NBI), S. Covino (INAF/Brera), A. J. Levan
(Univ. Warwick), G. Pugliese (Amsterdam), report on behalf of the
Stargate collaboration:
We observed the optical counterpart of GRB 180720B (Siegel et al., GCN
22973; Martone et al., GCN 22976) with the ESO VLT UT2 equipped with the
X-shooter spectrograph. Two spectra of 600 s each were secured starting
on 2018 July 21.384 UT (0.786 days after the GRB), covering the
wavelength range 3000-25000 AA.
A bright continuum is detected across the entire observed range. Several
absorption features are detected, which can be identified as due to Fe
II, Mg II, Mg I, and Ca II, all at z = 0.654. We also identify
fine-structure transitions due to both Fe II* and Ni II**, thus making
the redshift association with the GRB secure.
We acknowledge the ESO observing staff at Paranal, in particular Juan
Carlos Munoz, Emanuela Pompei, and Luca Sbordone.
- GCN Circular #22998
S. D. Barthelmy (GSFC), J. R. Cummings (CPI),
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. H. Siegel (PSU),
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 180720B (trigger #848890)
(Siegel et al., GCN Circ. 22973). The BAT ground-calculated position is
RA, Dec = 0.528, -2.925 deg which is
RA(J2000) = 00h 02m 06.8s
Dec(J2000) = -02d 55' 31.3"
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 8%.
The mask-weighted light curve shows a multi-peaked structure, with the main peak
occurs around ~T+11 s. The burst emission starts around ~T-20 s, although there might
be additional emission before the GRB came into the BAT FOV at ~T-57 s. The burst lasts
beyond the available event data range (until T+962 s). Analysis using the BAT survey data
shows that the burst emission extends at least till ~ T+2000 s, when Swift went into SAA
and no more data were collected. The burst came back into the BAT FOV at ~ T0+5626 s, and
the burst was no longer detected (signal-to-noise ratio < 3 sigma).
The time-averaged spectrum from T-20.0 to T+961.1 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.36 +- 0.03. The fluence in the 15-150 keV band is 8.6 +- 0.1 x 10^-05 erg/cm2.
The 1-sec peak photon flux measured from T+10.94 sec in the 15-150 keV band
is 67.9 +- 2.6 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/848890/BA/
- GCN Circular #23004
T. Horiuchi, H. Hanayama, M. Honma (IAO, NAOJ),
R. Itoh, K. L. Murata, Y. Tachibana, S. Harita, K. Morita
K. Shiraishi, K. Iida, M. Oeda, R. Adachi, S. Niwano,
Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:
We observed the optical counterpart of GRB 180720B
(Siegel et al., GCN 22973)
with the optical three color (g', Rc, and Ic) CCD cameras attached to
the Murikabushi 1m telescope of Ishigakijima Astronomical Observatory, Japan.
The observation started on 2018-07-20 17:11:26 UT, (~2.8 hours after
the burst). We detected the previously reported afterglow
(Martone et al., GCN 22976, Sasada et al., GCN 22977, Reva et al., GCN 22979)
in the Rc and Ic band.
The photometric results of the OT are listed below.
We used UCAC-4 catalog for flux calibration.
#T0+[hour] MID-UT T-EXP[sec] Rc Ic
-------------------------------------------------------------------
2.8 17:14:58 240 16.23+/-0.03 16.24+/-0.05
-------------------------------------------------------------------
T0+ : Elapsed time after the burst [hour]
T-EXP: Total Exposure time [sec]
- GCN Circular #23011
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, extremely bright GRB 180720B
(Swift-BAT detection: Siegel et al., GCN 22973, GCN 22975;
Fermi-LAT detection: Bissaldi and Racusin, GCN 22980;
Fermi-GBM detection: Roberts et al., GCN 22981)
triggered Konus-Wind at T0=51705.261 s UT (14:21:45.261).
The burst light curve shows a multi-peaked structure
with a total duration (T100) of ~125 s.
The emission is seen up to ~15 MeV.
As observed by Konus-Wind, the burst had a fluence of
(5.43 ± 0.26)x10^-4 erg/cm2 and a 64-ms peak energy flux,
measured from T0+15.168, of (9.70 ± 0.52)x10^-5 erg/cm2
(both in the 20 keV - 10 MeV energy range).
The time-integrated spectrum (measured from T0 to T0+119.808 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 = -1.01 (-0.06,+0.06),
the high energy photon index beta = -2.07 (-0.08,+0.07),
the peak energy Ep = 451 (-45,+52) keV,
chi2 = 102/97 dof.
The spectrum near the peak count rate (measured from T0+14.592 s
to T0+15.360 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 = -0.82 (-0.09,+0.10),
the high energy photon index beta = -2.27 (-0.22,+0.13),
the peak energy Ep = 779 (-127,+169) keV,
chi2 = 92/76 dof.
Assuming the redshift z=0.654 (Vreeswijk et al., GCN 22996)
and a standard cosmology model with H_0 = 70 km/s/Mpc,
Omega_M = 0.30, and Omega_Lambda = 0.70,
we estimate the following rest-frame parameters:
the isotropic energy release E_iso is ~6.0x10^53 erg,
the peak luminosity L_iso is ~1.8x10^53 erg/s,
and the rest-frame peak energy of the time-integrated spectrum,
Ep,z, is ~746 keV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB180720_T51705/
All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.
- GCN Circular #23017
Alan M. Watson (UNAM), Nat Butler (ASU), Rosa L. Becerra (UNAM), William
H. Lee (UNAM), Carlos Román-Zúñiga (UNAM), Alexander Kutyrev (GSFC), and
Eleonora Troja (GSFC) report:
We observed the field of GRB 180720B (Siegel et al., GCN Circ. 22973)
with the COATLI 50-cm telescope and interim imager at the Observatorio
Astronómico Nacional on the Sierra de San Pedro Mártir
(http://coatli.astroscu.unam.mx) from 2018-07-22 06:25 to 11:23 UTC
(from 40.07 to 45.03 hours after the trigger), obtaining a total of 4.06
hours of exposure in the w filter.
We detect the optical counterpart (Martone et al., GCN Circ. 22976) with
w = 20.07 +/- 0.02
These magnitudes are calibrated against the USNO-B1 catalog (adjusted to
an approximate AB system) and are not corrected for Galactic extinction
in the direction of the GRB.
We thank the COATLI technical team (Fernando Ángeles, Oscar Chapa,
Salvador Cuevas, Alejandro Farah, Jorge Fuentes, Rosalía Langarica,
Fernando Quirós, and Carlos Tejada) and the staff of the Observatorio
Astronómico Nacional.
- GCN Circular #23019
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 180720B (Siegel et al., GCN 22973) is a long GRB with isotropic energy
~6.0e53 erg (Frederiks et al., GCN 23011). It belongs to the long GRB
subclass of Binary Driven Hypernovae (BdHNe) (Ruffini et al., 2016, ApJ, 832, 136), with energies larger than 1e52 erg and GeV radiation, which allows the
determination of the black hole mass (Ruffini et al., arXiv:1803.05476). It
includes GRB 130427A associated to SN 2013cq (Ruffini et al., GCN 14526, Xu et al., GCN 14646), as well as GRB 160625B (Troja et al., 2017). The comparison of X-ray light-curves is attached [1], plotted in the rest frame of
the sources. These sources are polar views from the normal to the plane of
the binary progenitor (Ruffini et al., arXiv:1803.05476). In GRB 180720B, which has redshift z =3D 0.654 (GCN 22996), being a BdHN, a supernova is expected to peak, using the averaged observed value (Cano et al., 2016), at 21=2E8 +/ 4.3 day after the trigger (11 August 2018, uncertainty from August
7th to August 15th): the prolonged observations of the afterglow in all bands, especially the optical band, is recommended to further probe the nature of the supernova and of the newly born neutron star, strikingly constant in all BdHNe (see also Becerra et al., arXiv:1803.04356).
[1] Link: http://www.icranet.org/documents/20180721.jpg
Caption of figure: Three BdHNe with polar views from the normal to the plane of the binary progenitor, pointing to the similarities. GRB 130427A with
redshift z=3D0.34 is associated to the companion supernova SN 2013cq. GRB 160625B has redshift z=3D1.406, which is too far for the optical observation
of the associated supernova (Woosley & Bloom, 2006). GRB 180720B with redshift z=3D0.654 is expected to have the observation of an associated supernova.
- GCN Circular #23020
S. Schmalz (KIAM), F. Graziani (GAUSS). A. Pozanenko (IKI), A. Volnova
(IKI), E. Mazaeva (IKI), I. Molotov (KIAM) report on behalf of larger GRB
follow-up collaboration:
We observed the field of GRB 180720B (Swift-BAT detection: Siegel et al.,
GCN 22973, GCN 22975; Fermi-LAT detection: Bissaldi and Racusin, GCN 22980;
Fermi-GBM detection: Roberts et al., GCN 22981; MAXI/GSC detection: Negoro
et al., GCN 22993; Konus-Wind detection: Frederiks et al., GCN 23011)
with ORI-22 (22 cm) telescope of ISON-Castelgrande observatory starting on
July 20 (UT) 23:04:30. We obtained 150 images of 60 s exposure in Clear
filter. The optical afterglow (e.g. Martone et al. GCN 22976; Sasada et
al., GCN 22977; Reva et al., GCN 22979; Itoh et al., GCN 22983; Kann et
al., GCN 22985) is detected in separate images up to the end of series.
The coordinates of the optical afterglow are (J2000)
:02:06.792 -02:55:04:99 with uncertainties of about 0.5 arcsec in both
coordinates. Preliminary photometry of the afterglow at (UT, mid time)
23:22:21 is R =17.40 +/- 0.15. The photometry is based on nearby USNO-B1.0
(R2) stars.
- GCN Circular #23021
S.Covino, D. Fugazza (INAF/OAB), on behalf of the REM team, report:
We observed the field of GRB180720B (Siegel et al. GCN 22973) with the REM 60cm robotic telescope located at the ESO premise of La Silla (Chile).
The observations were performed starting from about 13.5 hours after the event and were carried in the g, r, i, z, J, H and K bands.
The optical counterpart (Martone et al. GCN 22976) is still detected in the optical and in the NIR bands. A preliminary photometry on the first H band set of frame gives:
H = 15.65 +- 0.22 at 13.7 hours from the GRB time.
Magnitudes are calibrated against the 2MASS catalogue.
- GCN Circular #23023
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-Amur robotic telescope (MASTER-Net: http://observ.pereplet.ru,
Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in
Russia (Blagoveschensk State Pedagogical University) was pointed to the
Swift GRB180720B (Siegel et al., GCN Circ #22973) 113 sec after trigger
time at 2018-07-20 14:23:37 UT.
So as the GRB was 4.6 degrees above the horizont, the good observations
started on 2018-07-20 15:21:50UT.
Galaxy latitude b = -63.07 degree.
The moon (58 % bright part) is 9 degrees above the horizon. The distance
between moon and object was 143.
The sun altitude was -17.19 degree.
The object observed till 2018-07-20 15:47:58
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
GRB180720B 27260 sec after trigger time at 2018-07-19 20:56:09 UT as
MASTER's LAT (Bissaldi et al GCN22980)alert inspection with polarization
filters.
MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic
Net", Advances in Astronomy, 2010, 30L )
discovered bright OT source at (RA, Dec) = 00h 02m 06.92s -02d 55m 05.6s
on 2018-07-19 20:56:09 UT.
The OT magnitude is ~16.8m .
There is no minor planet at this place.
We have reference image on 2016-05-04.12293 UT with unfiltered mlim = 18.1m.
The observations made on zenit distance = 16.7 degrees, galaxy latitude b
= -74.37 degree. The moon (61 % bright part) was 24 degrees above the
horizon.The sun altitude was -63.7 degree.
MASTER-SAAO reobserved this area on 2018-07-21 22:28:10-22:54:51UT as
MASTER's MAXI (Negoro et al GCN 22993) alert inspection with mlim=20.2
and unfiltered m_OT~19.1
The discovery and reference images are
http://master.sai.msu.ru/static/OT/MASTERGRB180720B.jpg
MASTER-Kislovodsk robotic telescope (MASTER-Net:
http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy,
vol. 2010, 30L) located in Russia (Pulkovo Solar Station) was pointed to
the GRB180720B (Siegel et al., GCN Circ #22973) 27457 sec after trigger
time at 2018-07-20 21:59:21 UT .
On our first (180s exposure) set MASTER-Kislovodsk auto-detection system
discovered OT with m_OT~17.0, automatical mlim~17.6.
The observations made on zenit distance = 25.66 degrees, galaxy latitude b
= -63.07 degree.
The moon (61 % bright part) is below the horizon(The altitude of Moon is
-8). The distance between moon and object is 138
The sun altitude is -24.87 degree.
The object observed till 2018-07-20 22:19:52
MASTER-IAC robotic telescope (MASTER-Net: http://observ.pereplet.ru,
Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in
Spain (IAC Teide Observatory) was pointed to the GRB180720B (Siegel et
al., GCN Circ #22973) 44691 sec after trigger time at 2018-07-21 02:46:35
UT . On our first (60s exposure) MASTER-IAC auto-detection system
discovered optical transient within Swift error-box with automatical
magnitude ~18.0.
The observations made on zenit distance = 43.01 degrees, galaxy latitude b
= -63.07 degree.
The moon (63 % bright part) is below the horizon(The altitude of Moon is
-15). The distance between moon and object is 136
The sun altitude is -36.01 degree.
The object observed till 2018-07-21 03:03:36
The visibility GRB error box (coord:0.5279, -2.9170 error_box: 0.05)
at trigger time at different MASTER sites:
obj: -47.70 sun: 29.73 - Tavrida (Crimea, Russia)
obj: -41.62 sun: 72.28 - IAC, Teide, (Tenerife, Spain)
obj: -54.25 sun: 15.39 - SAAO (Sutherland, SA)
obj: -46.85 sun: 23.59 - Kislovodsk (Russia)
obj: -29.98 sun: 15.28 - Ural(Kourovka, Russia)
obj: -10.74 sun: -8.46 - Tunka (near Baykal Lake, Russia)
obj: 4.55 sun: -17.19 - Amur(Blagoveschensk)
obj: 6.72 sun: 27.64 - OAFA (Argentina)
The message may be cited.
- GCN Circular #23024
M. Jelinek, J. Strobl, R. Hudec, C. Polasek (ASU CAS Ondrejov)
report:
We observed the position of the bright GRB 180720B (Siegel et al., GCN
22973 & GCN 22975) with the D50 telescope of the Astronomical Institute
Ondrejov, near Prague, Czech Republic. We performed a series of ~300x 20s
unfiltered exposures as soon as the position became accessible above local
horizon, between 9.8 and 12h after the trigger.
The optical afterglow (Martone et al., GCN 22976; Sasada et al., GCN
22977; Reva et al., GCN 22979; Itoh et al., GCN 22983) is clearly detected
in single 20 s images.
We confirm the stationary behaviour during our observations as reported by
Kann et al. (GCN 22985) - the afterglow might have faded as few as 0.04
mag between 10 and 11h after the GRB trigger.
- GCN Circular #23033
WeiKang Zheng and Alexei V. Filippenko (UC Berkeley) report on
behalf of the KAIT GRB team:
The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at
Lick Observatory, observed the field of Swift GRB 180720B
(Siegel et al., GCN 22973) each night from 21 to 24 UT, at a mean time
of 0.855, 1.886, 2.883 and 3.874 days, respectively, after the burst.
Observations were performed with a sequence in the B, V, R, I and
clear (roughly R) filters, and the exposure time was 60 s per image.
The optical afterglow (Martone et al., GCN 22976) was clearly detected
and we measure its clear band mag to be 18.5, 19.6, 20.5 and 20.9,
respectively, calibrated to the SDSS catalog.
- GCN Circular #23036
TITLE: GCN CIRCULAR
NUMBER: 23036
SUBJECT: GRB 18020B long follow up requested
DATE: 18/07/25 08:52:55 GMT
FROM: Arnon Dar at Technion-Israel Inst. of Tech
Long follow up of the afterglow of the extremely bright GRB
180720B (Swift-BAT detection: Siegel et al., GCN #22973, GCN
#22975; Fermi-LAT detection: Bissaldi and Racusin, GCN #22980;
Fermi-GBM detection: Roberts et al., GCN #22981; Konus Wind
detection: Frederiks et al. GCN 230110) is urged. It will provide
another critical test of GRB theories. Its current late-time X-ray
afterglow, measured with Swift XRT, decays like a single power-law
with a temporal index alpha=1.34+/-0.01 and an unabsorbed spectral
index beta=0.82+/-0.04 (Evans et al. Swift-XRT GRB lightcurve
repository). It satisfies well the Cannonball model closure relation
alpha=beta+1/2 (e.g., Dado and Dar, PhRvD, 94, 3007 (2016)) for
the late time unabsorbed afterglows of SN-GRBs (while those of
SN-less GRBs satisfy alpha=2, e.g., Dado and Dar arXiv:1807.08726).
An SN akin to SN1998bw may be resolved from the optical afterglows
around day ~15. An achromatic break in the late time afterglow
is expected only if the host galaxy is aligned near face on.
- GCN Circular #23037
Itai Sfaradi (HUJI), Joe Bright (Oxford), Assaf Horesh (HUJI), Rob Fender
(Oxford) ,
Sara Motta (Oxford), David Titterington, Yvette Perrott (MRAO, Cambridge)
report:
We observed the position of GRB180720B (GCN CIRCULAR #22973) with the
Arcminute Microkelvin Imager Large Array (AMI-LA; Zwart et al. 2008; Hickish
et al. 2018) at 15.5 GHz on 2018-07-22.21 for 3.9 hours.
We clearly detect a source at the phase center, fitting the source with the
CASA task IMFIT
provides an integrated flux density of ~ 1 mJy and a position of RA:
00:02:07.02,
Dec: -02 55 02.224 with a synthesized beam major and minor FWHM of 93’’ and
27’’ respectively
(consistent with the position reported in GCN CIRCULAR #22973).
The custom pipeline REDUCE_DC (e.g. Perrott et al. 2015) was used to
calibrate
and flag the data, with 3C286 as the absolute flux calibrator and J2357-0152
as the interleaved phase calibrator.
We plan to continue monitoring this source, and would like to thank the
MRAO staff for carrying out these observations.
- GCN Circular #23040
L. Izzo, D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), C. C. Thoene, K. Bensch, M. Blazek (HETH/IAA-CSIC), M. C. Diaz-Martin, and S. Rodriguez-Llano (OAJ) report:
We observed the field of the Swift-BAT GRB 180720B (Siegel et al. GCN 22973), detected also by Fermi-LAT (Bissaldi et al. GCN 22980), with the 0.8m telescope of the Observatorio Astrofisico de Javalambre (Teruel, Spain). Observations consisted of a series of 3x300 s griz exposures, starting at 01:12:55 UT (10.85 hr after the GRB trigger). The afterglow is clearly detected at a position consistent with the one reported by Martone et al. (GCN 22976).
We measure a magnitude of r(AB) = 17.77+/- 0.05 mag at an average time of 01:37:14 UT (11.26 hr after the GRB trigger), as compared to nearby SDSS stars.
- GCN Circular #23041
E. C. Bellm (UW) and S. B. Cenko (GSFC) report:
We have analyzed 38 ksec of NuSTAR data for GRB 180720B (M. H. Siegel et
al., GCN Circ. 22973), from 243 ksec to 318 ksec after the BAT trigger.
NuSTAR detects emission from the X-ray afterglow to approximately 30 keV.
The NuSTAR spectrum can be well-modeled from 3-30 keV by an absorbed power
law with spectral index 1.80+/-0.06, consistent with the value reported
by XRT (K. L. Page et al., GCN Circ. 22984). The 3-30 keV flux was
4.8+/-0.2 x 10^-12 erg cm^-2 s^-1.
We thank Karl Forster and the NuSTAR operations team for their assistance
executing these TOO observations.
- GCN Circular #23042
M. L. Cherry (LSU), A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita, Y. Kawakubo,
A. Tezuka, S. Matsukawa, H. Onozawa, T. Ito, H. Morita, Y. Sone (AGU),
K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), I. Takahashi (IPMU),
Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U),
W. Ishizaki (ICRR), S. Ricciarini (U of Florence),
A. V. Penacchioni, P. S. Marrocchesi (U of Siena)
and the CALET collaboration:
The extremely bright, long GRB 180720B (Swift-BAT trigger #848890:
Siegel et al., GCN Circ. 22973, Barthelmy et al. GCN Circ. 22998;
Fermi-LAT detection: Bissaldi and Racusin, GCN Circ. 22980;
Fermi-GBM observation: Roberts and Meegan, GCN Circ. 22981;
MAXI/GGS detection: Negoro et al., GCN Circ. 22993;
Konus-Wind observation: Frederiks et al., GCN Circ. 23011)
triggered the CALET Gamma-ray Burst Monitor (CGBM)
at 14:21:40.948 UTC on 20 July 2018. Because of a problem in
one of the ground alert processing script, the GCN notice was not
distributed automatically for this event. The burst signal was seen
by all CGBM detectors.
The CGBM data cover the time interval from T-243 sec to T+1449 sec
(when the HV was on and the source was in the CGBM FoV).
The burst light curve shows the main emission episode comprised
of several bright overlapped pulses which starts
at T-2.9 sec, peaks at 15.3 sec, and ends at T+54.0 sec,
followed by the weak tail seen at least up to T+120.1 sec.
The T90 and the T50 durations measured by the SGM data are
51.1 +- 3.0 sec and 15.4 +- 1.4 sec (40-1000 keV), respectively.
No any precursor is seen in the time interval from T-243 sec to T-2.9 sec.
The time-averaged spectrum of the main episode (measured by the SGM
from T+0.8 sec to T+52.8 sec) is best fit in the 30 keV - 20 MeV range
by a GRB (Band) model with alpha = -1.29 +- 0.04,
Epeak = 686(-77, +88) keV, and beta = -2.23(-0.12, +0.09)
(chi2 = 254.4/236 dof). The emission is seen up to ~20 MeV.
The resulting fluence in the 30 keV - 10 MeV range is
5.79(-0.19, +0.20)x10^-4 erg/cm2 .
Assuming a redshift of z=0.654 (Vreeswijk et al., GCN 22996)
and a FlatLambdaCDM cosmology with H0=68 km/s/Mpc and Omega_M=0.308
(Planck Collaboration 2016, A&A, 594, A13 (Paper XIII)),
the isotropic energy release, Eiso, is 6.82(-0.22, 0.24)x10^53 erg.
The quoted errors are at the 90% CL.
The ground processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1216131585/
All the quoted values are preliminary.
The CALET data used in this analysis are provided by the Waseda CALET
Operation Center located at the Waseda University.
- GCN Circular #23073
Poonam Chandra (NCRA-TIFR), A. J. Nayana (NCRA-TIFR), Dipankar Bhattacharya (IUCAA), S. Bradley Cenko (NASA) and Alessandra Corsi (Texas-Tech) report:
We observed GRB 180720B (Siegel et al. GCN 22973) with the Giant Metrewave Radio Telescope at the 1.4 GHz band on 2018 Jul 29.99 UT. We detect a radio afterglow with the flux density of ~370+/-59 uJy at the optical position (Martone et al. GCN 22976).
We thank the staff of the GMRT that made these observations possible. GMRT is run by the National Centre for Radio Astrophysics of the Tata Institute of Fundamental Research. More observations are planned.
Previous IAU Circulars 
