Gamma-ray Burst 180620A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

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Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 20 Jun 18 08:35:17 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     843122,   Seg_Num: 0
GRB_RA:          279.883d {+18h 39m 32s} (J2000),
                 280.076d {+18h 40m 18s} (current),
                 279.360d {+18h 37m 26s} (1950)
GRB_DEC:         +23.265d {+23d 15' 55"} (J2000),
                 +23.283d {+23d 16' 59"} (current),
                 +23.219d {+23d 13' 08"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       4387 [cnts]    Image_Peak=214 [image_cnts]
TRIGGER_DUR:     1.024 [sec] 
TRIGGER_INDEX:   138     E_range: 15-50 keV
BKG_INTEN:       27892 [cnts]
BKG_TIME:        30882.86 SOD {08:34:42.86} UT
BKG_DUR:         8 [sec]
GRB_DATE:        18289 TJD;   171 DOY;   18/06/20
GRB_TIME:        30898.03 SOD {08:34:58.03} UT
GRB_PHI:          49.20 [deg]
GRB_THETA:        31.26 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     15.29 [sigma]
IMAGE_SIGNIF:    9.35 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +1  +0  +0  +0 +67  +0 
SUN_POSTN:        88.90d {+05h 55m 35s}  +23.43d {+23d 25' 57"}
SUN_DIST:        132.04 [deg]   Sun_angle= 11.3 [hr] (West of Sun)
MOON_POSTN:      179.65d {+11h 58m 37s}   +4.52d {+04d 31' 07"}
MOON_DIST:        97.73 [deg]
MOON_ILLUM:      49 [%]
GAL_COORDS:       52.70, 12.86 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      283.18, 46.25 [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 = 136.36,20.60 [deg].

GCN NOTICE

 
TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Wed 20 Jun 18 08:35:54 UT
NOTICE_TYPE:    INTEGRAL SPI ACS Trigger
TRIGGER_NUM:    8080,   Sub_Num: 0
GRB_INTEN:      9.14 [sigma]   
GRB_TIME:       30901.01 SOD {08:35:01.01} UT
GRB_DATE:       18289 TJD;   171 DOY;   18/06/20
COMMENTS:       INTEGRAL SPI_ACS GRB Trigger.
COMMENTS:       Time_Scale=2.0000 and Time_Error=1.0000.
COMMENTS:
COMMENTS:       NOTE: This SPIACS event is temporally(3.0<100sec) coincident with the SWIFT_BAT event (trignum=843122).
COMMENTS:
COMMENTS:       The SPIACS lightcurve can be found at:
COMMENTS:       ftp://isdcarc.unige.ch/arc/FTP/ibas/spiacs/2018-06/2018-06-20T08-35-00.9636-19+54-19344-0.lc

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 20 Jun 18 08:38:47 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     843122,   Seg_Num: 0
GRB_RA:          279.883d {+18h 39m 32s} (J2000),
                 280.076d {+18h 40m 18s} (current),
                 279.360d {+18h 37m 26s} (1950)
GRB_DEC:         +23.265d {+23d 15' 55"} (J2000),
                 +23.283d {+23d 16' 59"} (current),
                 +23.219d {+23d 13' 08"} (1950)
GRB_DATE:        18289 TJD;   171 DOY;   18/06/20
GRB_TIME:        30898.03 SOD {08:34:58.03} UT
TRIGGER_INDEX:   138
GRB_PHI:          49.20 [deg]
GRB_THETA:        31.26 [deg]
DELTA_TIME:      -76.00 [sec]
TRIGGER_DUR:     1.024 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     15.29 [sigma]
IMAGE_SIGNIF:    9.35 [sigma]
LC_URL:          sw00843122000msb.lc
SUN_POSTN:        88.90d {+05h 55m 36s}  +23.43d {+23d 25' 57"}
SUN_DIST:        132.04 [deg]   Sun_angle= 11.3 [hr] (West of Sun)
MOON_POSTN:      179.69d {+11h 58m 45s}   +4.51d {+04d 30' 26"}
MOON_DIST:        97.71 [deg]
MOON_ILLUM:      49 [%]
GAL_COORDS:       52.70, 12.86 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      283.18, 46.25 [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 = 136.36,20.60 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 20 Jun 18 08:39:31 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     843122,   Seg_Num: 0
POINT_RA:        279.889d {+18h 39m 33s} (J2000)
POINT_DEC:       +23.290d {+23d 17' 25"} (J2000)
IMG_START_DATE:  18289 TJD;   171 DOY;   18/06/20
IMG_START_TIME:  31165.14 SOD {08:39:25.14} UT,   267.1 [sec] since BAT Trigger Time
COUNTS:          4    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        1    Max_iter_allowed= 4
ERROR_CODE:      1
COMMENTS:        SWIFT-XRT Nack Position.  
COMMENTS:        No source found in the image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 20 Jun 18 08:42:22 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     843122,   Seg_Num: 0
POINT_RA:        279.889d {+18h 39m 33s} (J2000)
POINT_DEC:       +23.291d {+23d 17' 26"} (J2000)
POINT_ROLL:      13.633d
IMG_START_DATE:  18289 TJD;   171 DOY;   18/06/20
IMG_START_TIME:  31168.32 SOD {08:39:28.32} UT,   270.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.328
N_STARS:         190
X_OFFSET:        312 [pixels]
Y_OFFSET:        670 [pixels]
X_MAX:           1271 [pixels]
Y_MAX:           1629 [pixels]
DET_THRESH:      13
PHOTO_THRESH:    6
SL_URL:          sw00843122000msufc0270.fits
SUN_POSTN:        88.90d {+05h 55m 37s}  +23.43d {+23d 25' 57"}
SUN_DIST:        132.01 [deg]   Sun_angle= 11.3 [hr] (West of Sun)
MOON_POSTN:      179.72d {+11h 58m 52s}   +4.50d {+04d 29' 44"}
MOON_DIST:        97.68 [deg]
MOON_ILLUM:      49 [%]
GAL_COORDS:       52.73, 12.87 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      283.19, 46.28 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 20 Jun 18 08:42:36 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     843122,   Seg_Num: 0
POINT_RA:        279.889d {+18h 39m 33s} (J2000)
POINT_DEC:       +23.291d {+23d 17' 26"} (J2000)
POINT_ROLL:      13.633d
IMG_START_DATE:  18289 TJD;   171 DOY;   18/06/20
IMG_START_TIME:  31168.32 SOD {08:39:28.32} UT,   270.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.328
N_STARS:         190
X_OFFSET:        312 [pixels]
Y_OFFSET:        670 [pixels]
X_MAX:           1271 [pixels]
Y_MAX:           1629 [pixels]
DET_THRESH:      13
PHOTO_THRESH:    6
SL_URL:          sw00843122000msufc0270.fits
SUN_POSTN:        88.90d {+05h 55m 37s}  +23.43d {+23d 25' 57"}
SUN_DIST:        132.01 [deg]   Sun_angle= 11.3 [hr] (West of Sun)
MOON_POSTN:      179.72d {+11h 58m 53s}   +4.49d {+04d 29' 42"}
MOON_DIST:        97.68 [deg]
MOON_ILLUM:      49 [%]
GAL_COORDS:       52.73, 12.87 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      283.19, 46.28 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 20 Jun 18 08:43:58 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     843122,   Seg_Num: 0
POINT_RA:        279.889d {+18h 39m 33s} (J2000)
POINT_DEC:       +23.291d {+23d 17' 26"} (J2000)
ROLL:            13.633d
IMG_START_DATE:  18289 TJD;   171 DOY;   18/06/20
IMG_START_TIME:  31168.32 SOD {08:39:28.32} UT,   270.3 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     551176789
X_OFFSET:        631 [pixels]
Y_OFFSET:        989 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       791
Y_GRB_POS:       1149
BINNING_INDEX:   1
IM_URL:          sw00843122000msuni0292.fits
SUN_POSTN:        88.90d {+05h 55m 37s}  +23.43d {+23d 25' 57"}
SUN_DIST:        132.01 [deg]   Sun_angle= 11.3 [hr] (West of Sun)
MOON_POSTN:      179.73d {+11h 58m 56s}   +4.49d {+04d 29' 26"}
MOON_DIST:        97.67 [deg]
MOON_ILLUM:      49 [%]
GAL_COORDS:       52.73, 12.87 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      283.19, 46.28 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 20 Jun 18 08:43:17 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     843122,   Seg_Num: 0
GRB_RA:          279.8957d {+18h 39m 34.96s} (J2000),
                 280.0888d {+18h 40m 21.31s} (current),
                 279.3729d {+18h 37m 29.50s} (1950)
GRB_DEC:         +23.2441d {+23d 14' 38.7"} (J2000),
                 +23.2619d {+23d 15' 42.9"} (current),
                 +23.1975d {+23d 11' 51.0"} (1950)
GRB_ERROR:       3.7 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  18289 TJD;   171 DOY;   18/06/20
IMG_START_TIME:  31188.00 SOD {08:39:48.00} UT,   290.0 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:        88.90d {+05h 55m 37s}  +23.43d {+23d 25' 57"}
SUN_DIST:        132.06 [deg]   Sun_angle= 11.3 [hr] (West of Sun)
MOON_POSTN:      179.73d {+11h 58m 54s}   +4.49d {+04d 29' 34"}
MOON_DIST:        97.69 [deg]
MOON_ILLUM:      49 [%]
GAL_COORDS:       52.69, 12.84 [deg] galactic lon,lat of the burst
ECL_COORDS:      283.20, 46.23 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.58% < P(seren) < 1.1%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 20 Jun 18 08:44:14 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     843122,   Seg_Num: 0
POINT_RA:        279.889d {+18h 39m 33s} (J2000)
POINT_DEC:       +23.291d {+23d 17' 26"} (J2000)
ROLL:            13.633d
IMG_START_DATE:  18289 TJD;   171 DOY;   18/06/20
IMG_START_TIME:  31168.32 SOD {08:39:28.32} UT,   270.3 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     551176789
X_OFFSET:        631 [pixels]
Y_OFFSET:        989 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       791
Y_GRB_POS:       1149
BINNING_INDEX:   1
IM_URL:          sw00843122000msuni0292.fits
SUN_POSTN:        88.90d {+05h 55m 37s}  +23.43d {+23d 25' 57"}
SUN_DIST:        132.01 [deg]   Sun_angle= 11.3 [hr] (West of Sun)
MOON_POSTN:      179.73d {+11h 58m 56s}   +4.49d {+04d 29' 23"}
MOON_DIST:        97.67 [deg]
MOON_ILLUM:      49 [%]
GAL_COORDS:       52.73, 12.87 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      283.19, 46.28 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 20 Jun 18 08:46:02 UT
NOTICE_TYPE:     Swift-UVOT Position
TRIGGER_NUM:     843122,   Seg_Num: 0
GRB_RA:          279.8961d {+18h 39m 35.06s} (J2000),
                 280.0892d {+18h 40m 21.40s} (current),
                 279.3733d {+18h 37m 29.60s} (1950)
GRB_DEC:         +23.2443d {+23d 14' 39.4"} (J2000),
                 +23.2621d {+23d 15' 43.7"} (current),
                 +23.1977d {+23d 11' 51.7"} (1950)
GRB_ERROR:       1.1 [arcsec radius, statistical only]
GRB_MAG:         18.23 +/- 0.40 [mag]
FILTER:          10, White
IMG_START_DATE:  18289 TJD;   171 DOY;   18/06/20
IMG_START_TIME:  31165.00 SOD {08:39:25.00} UT,   267.0 [sec] since BAT Trigger Time
SUN_POSTN:        88.91d {+05h 55m 37s}  +23.43d {+23d 25' 57"}
SUN_DIST:        132.06 [deg]   Sun_angle= 11.3 [hr] (West of Sun)
MOON_POSTN:      179.75d {+11h 59m 00s}   +4.48d {+04d 29' 02"}
MOON_DIST:        97.67 [deg]
MOON_ILLUM:      49 [%]
GAL_COORDS:       52.69, 12.84 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      283.20, 46.23 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT UVOT Position Notice.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        Result based on srclist data.  
COMMENTS:        Notice generated automatically.

GCN Circular #22798
P. A. Evans (U Leicester), S. D. Barthelmy (GSFC), A. P. Beardmore (U Leicester), A. A. Breeveld (UCL-MSSL), S. W. K Emery (UCL-MSSL), A. Y. Lien (GSFC/UMBC), K. L. Page (U Leicester), D. M. Palmer (LANL), R. L. C. Starling (U Leicester) and A. Tohuvavohu (PSU) report on behalf of the Neil Gehrels Swift Observatory Team:
At 08:34:58 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 180620A (trigger=843122). Swift slewed to the burst with a 3 min delay. The BAT on-board calculated location is RA, Dec 279.883, +23.265, which is
```
   RA(J2000)  =  18h 39m 32s
   Dec(J2000) = +23d 15' 55"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows several overlapping peaks with a total duration of about 25 sec. The peak count rate was ~8000 counts/sec (15-350 keV), at ~12 sec after the trigger.
The XRT began observing the field at 08:39:25.1 UT, 267.1 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 279.89575, 23.24373 which is equivalent to:
```
   RA(J2000)  = 18h 39m 34.98s
   Dec(J2000) = +23d 14' 37.4"
```
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This location is 87 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper.
A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 1.60 x 10^21 cm^-2 (Willingale et al. 2013).
UVOT took a finding chart exposure of nominal 150.000 seconds with the White filter starting 270 seconds after the BAT trigger. There is a candidate afterglow in the list of sources generated on-board at
```
  RA(J2000)  =	18:39:35.08 = 279.89618
  DEC(J2000) = +23:14:39.7  =  23.24437
```
with a 90%-confidence error radius of about 1.10 arc sec. This position is 1.7 arc sec. from the center of the XRT error circle. The estimated magnitude is 18.24. No correction has been made for the expected extinction corresponding to E(B-V) of 0.13.
Burst Advocate for this burst is P. A. Evans (pae9 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:     Wed 20 Jun 18 08:54:16 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     843122,   Seg_Num: 0
POINT_RA:        279.887d {+18h 39m 33s} (J2000)
POINT_DEC:       +23.293d {+23d 17' 34"} (J2000)
POINT_ROLL:      13.631d
IMG_START_DATE:  18289 TJD;   171 DOY;   18/06/20
IMG_START_TIME:  31770.40 SOD {08:49:30.40} UT,   872.4 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.881
N_STARS:         190
X_OFFSET:        72 [pixels]
Y_OFFSET:        430 [pixels]
X_MAX:           1511 [pixels]
Y_MAX:           1869 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    6
SL_URL:          sw00843122000msufc0872.fits
SUN_POSTN:        88.91d {+05h 55m 39s}  +23.43d {+23d 25' 57"}
SUN_DIST:        132.01 [deg]   Sun_angle= 11.3 [hr] (West of Sun)
MOON_POSTN:      179.82d {+11h 59m 18s}   +4.46d {+04d 27' 26"}
MOON_DIST:        97.60 [deg]
MOON_ILLUM:      49 [%]
GAL_COORDS:       52.73, 12.87 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      283.19, 46.28 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 20 Jun 18 08:54:31 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     843122,   Seg_Num: 0
POINT_RA:        279.887d {+18h 39m 33s} (J2000)
POINT_DEC:       +23.293d {+23d 17' 34"} (J2000)
POINT_ROLL:      13.631d
IMG_START_DATE:  18289 TJD;   171 DOY;   18/06/20
IMG_START_TIME:  31770.40 SOD {08:49:30.40} UT,   872.4 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.881
N_STARS:         190
X_OFFSET:        72 [pixels]
Y_OFFSET:        430 [pixels]
X_MAX:           1511 [pixels]
Y_MAX:           1869 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    6
SL_URL:          sw00843122000msufc0872.fits
SUN_POSTN:        88.91d {+05h 55m 39s}  +23.43d {+23d 25' 57"}
SUN_DIST:        132.01 [deg]   Sun_angle= 11.3 [hr] (West of Sun)
MOON_POSTN:      179.83d {+11h 59m 18s}   +4.46d {+04d 27' 23"}
MOON_DIST:        97.60 [deg]
MOON_ILLUM:      49 [%]
GAL_COORDS:       52.73, 12.87 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      283.19, 46.28 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 20 Jun 18 08:55:47 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     843122,   Seg_Num: 0
POINT_RA:        279.887d {+18h 39m 33s} (J2000)
POINT_DEC:       +23.293d {+23d 17' 34"} (J2000)
ROLL:            13.631d
IMG_START_DATE:  18289 TJD;   171 DOY;   18/06/20
IMG_START_TIME:  31770.40 SOD {08:49:30.40} UT,   872.4 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     551177391
X_OFFSET:        631 [pixels]
Y_OFFSET:        989 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       791
Y_GRB_POS:       1149
BINNING_INDEX:   1
IM_URL:          sw00843122000msuni0894.fits
SUN_POSTN:        88.91d {+05h 55m 39s}  +23.43d {+23d 25' 57"}
SUN_DIST:        132.01 [deg]   Sun_angle= 11.3 [hr] (West of Sun)
MOON_POSTN:      179.84d {+11h 59m 21s}   +4.45d {+04d 27' 08"}
MOON_DIST:        97.59 [deg]
MOON_ILLUM:      49 [%]
GAL_COORDS:       52.73, 12.87 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      283.19, 46.28 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 20 Jun 18 08:54:51 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     843122,   Seg_Num: 0
GRB_RA:          279.8958d {+18h 39m 34.99s} (J2000),
                 280.0889d {+18h 40m 21.33s} (current),
                 279.3730d {+18h 37m 29.52s} (1950)
GRB_DEC:         +23.2439d {+23d 14' 38.0"} (J2000),
                 +23.2617d {+23d 15' 42.2"} (current),
                 +23.1973d {+23d 11' 50.3"} (1950)
GRB_ERROR:       2.0 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  18289 TJD;   171 DOY;   18/06/20
IMG_START_TIME:  31188.00 SOD {08:39:48.00} UT,   290.0 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:        88.91d {+05h 55m 39s}  +23.43d {+23d 25' 57"}
SUN_DIST:        132.06 [deg]   Sun_angle= 11.3 [hr] (West of Sun)
MOON_POSTN:      179.83d {+11h 59m 19s}   +4.46d {+04d 27' 19"}
MOON_DIST:        97.61 [deg]
MOON_ILLUM:      49 [%]
GAL_COORDS:       52.69, 12.84 [deg] galactic lon,lat of the burst
ECL_COORDS:      283.20, 46.23 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        This is an Update Notice -- the RA,Dec values herein supersede the previous XRT_POS Notice.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        This position was enhanced using UVOT field astrometry.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.58% < P(seren) < 1.1%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 20 Jun 18 08:56:00 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     843122,   Seg_Num: 0
POINT_RA:        279.887d {+18h 39m 33s} (J2000)
POINT_DEC:       +23.293d {+23d 17' 34"} (J2000)
ROLL:            13.631d
IMG_START_DATE:  18289 TJD;   171 DOY;   18/06/20
IMG_START_TIME:  31770.40 SOD {08:49:30.40} UT,   872.4 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     551177391
X_OFFSET:        631 [pixels]
Y_OFFSET:        989 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       791
Y_GRB_POS:       1149
BINNING_INDEX:   1
IM_URL:          sw00843122000msuni0894.fits
SUN_POSTN:        88.91d {+05h 55m 39s}  +23.43d {+23d 25' 57"}
SUN_DIST:        132.01 [deg]   Sun_angle= 11.3 [hr] (West of Sun)
MOON_POSTN:      179.84d {+11h 59m 21s}   +4.45d {+04d 27' 06"}
MOON_DIST:        97.59 [deg]
MOON_ILLUM:      49 [%]
GAL_COORDS:       52.73, 12.87 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      283.19, 46.28 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN Circular #22799
Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), Jes=FAs Gonz=E1lez (UNAM), Carlos Rom=E1n-Z=FA=F1iga= (UNAM), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.), and Vicki Toy (UMD) report:
We observed the field of GRB 180620A (Evans, et al., GCN 22798) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astron=F3mico Nacional on Sierra San Pedro M=E1rtir from 2018/06 20.36 to 2018/06 20.38 UTC (0.03 to 0.47 hours after the BAT trigger), obtaining a total of 0.36 hours exposure in the r and i bands.
For a source within the Swift-XRT error circle, in comparison with the USNO-B1 and 2MASS catalogs, we obtain the following detections:
```
  r	=3D 18.01 +/- 0.01
  i	=3D 17.71 +/- 0.01
```
These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. We observe the rise and initial decline of the afterglow.
We thank the staff of the Observatorio Astron=F3mico Nacional in San Pedro M=E1rtir. Further observations are planned.
GCN Circular #22800
L. Elenin (KIAM), A. Pozanenko (IKI), A. Volnova (IKI), E. Mazaeva, I. Molotov (KIAM) report on behalf of larger GRB follow-up collaboration:
We observed the field of the Swift GRB 180620A (Evans et al., GCN 22798) with ISON-NM observatory. Observation started 84 s after burst trigger. We find fading object in coordinates (J2000) 18:39:35.09 +23:14:39.0 which correspond to the OT candidate (Evans et al., GCN 22798). Preliminary photometry of the OT in the first image started on 2018-06-20T08:36:21.666 is 17.1m in clear filter. Observation is ongoing.
GCN Circular #22801
N.Tyurina, V. Lipunov, E. Gorbovskoy, V.Kornilov, A.Kuznetsov, I. Gorbunov, D. Vlasenko, D.Zimnukhov, D.Kuvshinov, P.Balanutsa, V.Vladimirov Lomonosov Moscow State University, Sternberg Astronomical Institute, Moscow State University
R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias
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, C. Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)
D. Buckley South African Astronomical Observatory
O. Gres, N.M.Budnev , Yu.Ishmuhametova Irkutsk State University
A. Gabovich, V. Yurkov, Yu. Sergienko Blagoveschensk Educational State University, Blagoveschensk
MASTER-OAFA robotic telescope (MASTER-Net: http://observ.pereplet.ru Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) , located in Argentina (OAFA observatory of San Juan National University), was pointed to the Swift GRB180620A ( Evans et al. GCN #22798) 20 sec after Notice and 41 sec after trigger time at 2018-06-20 08:35:39 UT.
We see OT at Swift UVOT coordinates ~17 mag (Evans et al. GCN #22798).
====================================================================
The observations made on zenit distance = 72 degrees, galaxy latitude b = 12 degree. The moon (49 % bright part) below the horizon (The altitude of the Moon is -50 degree ). The sun altitude is -37.3 degree. The object can be observed till 2018-06-20 10:23:39.
GCN Circular #22802
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team.
Using 1128 s of XRT Photon Counting mode data and 1 UVOT images for GRB 180620A, 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 = 279.89648, +23.24418 which is equivalent to:
```
RA (J2000): 18h 39m 35.15s
Dec (J2000): +23d 14' 39.0"
```
with an uncertainty of 1.8 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 #22803
C. Guidorzi (U. Ferrara), S. Kobayashi (LJMU), C.G. Mundell (U. Bath), A. Gomboc (U. Nova Gorica), I.A. Steele (LJMU), A. Cucchiara (U. of Virgin Islands) on behalf of a large collaboration report:
The LCO 1-m unit at McDonald Observatory began observing Swift GRB 180620A (Evans et al. GCN 22798) on June 20, 08:55 UT (20 min since the GRB trigger time) with the SDSS griz filters. The optical counterpart (Evans et al.; Butler et al. GCN 22799; Elenin et al. GCN 22800; Tyurina et al. GCN 22801) is clearly detected in each individual frame with the following magnitudes:
```
Mid Time since GRB=A0=A0=A0 Exposure=A0=A0=A0=A0=A0=A0=A0=A0 Filter=A0=A0=
=A0=A0=A0=A0=A0 Magnitude
(hrs)=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 (s)
------------------------------------------------------------------
0.349=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 1x120=A0=A0=A0=A0=A0=
=A0=A0=A0=A0=A0=A0 SDSS-R=A0=A0=A0=A0=A0=A0=A0 18.63 +- 0.04
0.583=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 1x120=A0=A0=A0=A0=A0=
=A0=A0=A0=A0=A0=A0 SDSS-I=A0=A0=A0=A0=A0=A0=A0 18.27 +- 0.04
------------------------------------------------------------------
```
as calibrated against nearby PanSTARRS objects.
GCN Circular #22805
A. A. Breeveld (UCL-MSSL) and P. A. Evans (U. Leicester) report on=20 behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 180620A=20 270 s after the BAT trigger (Evans et al., GCN Circ. 22798). A fading source consistent with the XRT position (Osborne et al. GCN=20 Circ. 22802), and also detected by Butler et al. (GCN Circ. 22799),=20 Elenin et al. (GCN Circ. 22800), Tyurina et al. (GCN Circ. 22801) and=20 Guidorzi et al. (GCN Circ. 22803), is detected in the initial UVOT=20 exposures. The detection in the UVOT uvw2 filter implies a redshift=20 limit of 1.2.
The preliminary UVOT position is:
```
     RA  (J2000) =3D  18:39:35.09 =3D 279.89619 (deg.)
     Dec (J2000) =3D +23:14:39.1  =3D  23.24419 (deg.)
```
with an estimated uncertainty of 0.43 arc sec. (radius, 90% confidence).
Preliminary detections using the UVOT photometric system (Breeveld et=20 al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white              270          420          147         17.68 =B1 0.04
v                  427         1420          117         18.43 =B1 0.19
b                  525          717           39         18.77 =B1 0.20
u                  500          692           39         17.92 =B1 0.17
w1                 476         2158          194         18.86 =B1 0.20
m2                 623         7111          391         19.65 =B1 0.27
w2                 574         8136          588         20.00 =B1 0.23
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) =3D 0.13 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #22806
Alan M. Watson (UNAM), Nat Butler (ASU), Rosa L. Becerra (UNAM), William H. Lee (UNAM), Carlos Rom=E1n-Z=FA=F1iga (UNAM), Alexander Kutyrev (GSFC)= , and Eleonora Troja (GSFC) report:
We observed the field of GRB 180620A (Evans et al., GCN 22798) with the COATLI 50-cm telescope and interim imager at the Observatorio Astron=F3mico Nacional on the Sierra de San Pedro M=E1rtir (http://coatli.astroscu.unam.mx) from 2018-06-20 08:35:37 to 11:17:31 (from 39.2 seconds after the trigger or 21.1 seconds after the alert to 2.7 hours after the trigger), obtaining a total of 6250 seconds of exposure in the w filter.
We detect the source reported by Butler et al. (GCN Circ. 22799) with
w =3D 18.00 +/- 0.02
This magnitude is in the USNO system and is not corrected for Galactic extinction in the direction of the GRB.
Our light curve shows a sharp initial fall from 16.5 mag to 17.3 mag, followed by a slower rise to 16.7 mag (also seen by Butler et al.), followed by a monotonic fall to 19.0 mag.
We thank the COATLI technical team (Fernando =C1ngeles, Oscar Chapa, Salvador Cuevas, Alejandro Farah, Jorge Fuentes, Rosal=EDa Langarica, Fernando Quir=F3s, and Carlos Tejada) and the staff of the Observatorio Astron=F3mico Nacional.
GCN Circular #22808
A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), A. Tohuvavohu (PSU), S. J. LaPorte (PSU), J.A. Kennea (PSU), S.L. Gibson (U. Leicester), Z. Liu (NAOC / U. Leicester), J.P. Osborne (U. Leicester), P. D'Avanzo (INAF-OAB) and P.A. Evans report on behalf of the Swift-XRT team:
We have analysed 9.6 ks of XRT data for GRB 180620A (Evans et al. GCN Circ. 22798), from 274 s to 23.4 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN Circ. 22802).
The late-time light curve (from T0+6.1 ks) can be modelled with a power-law decay with a decay index of alpha=2.16 (+/-0.13).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.46 (+0.10, -0.08). The best-fitting absorption column is 1.76 (+0.43, -0.16) x 10^21 cm^-2, consistent with the Galactic value of 1.6 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.9 x 10^-11 (5.6 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     1.76 (+0.43, -0.16) x 10^21 cm^-2
Galactic foreground: 1.6 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.46 (+0.10, -0.08)
```
If the light curve continues to decay with a power-law decay index of 2.16, the count rate at T+24 hours will be 2.3 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.1 x 10^-13 (1.3 x 10^-13) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00843122.
This circular is an official product of the Swift-XRT team.
GCN Circular #22811
Z.P. Zhu, D. Xu, J.B. Zhang (NAOC), X. Zhang, J.H. Liu (XAO) report
We observed the field of GRB 180620A (Evans et al., GCN 22790) using the 2.16-m telescope located at Xinglong, Hebei, China, equipped with the BFOSC camera. We obtained 3x600s R-band frames, starting at 12:39:01 UT on 2018-06-20, i.e., 4.068 hrs after the BAT trigger.
The GRB's optical afterglow (Evans et al., GCN 22790; Butler et al., GCN 22799; Elenin et al., GCN 22800; Tyurina et al., GCN 22801; Guidorzi et al., GCN 22803) is clearly detected in each frame. Preliminary photometry shows the afterglow has decayed to m(R)~20.0, calibrated with nearby USNO B1 stars.
We acknowledge the excellent support from the Xinglong staff, particularly Xiao Feng and Huijuan Wang, in obtaining these observations.
GCN Circular #22812
WeiKang Zheng and Alex Filippenko (UC Berkeley) report on behalf of the KAIT GRB team:
The 0.76-m Katzman Automatic Imaging Telescope (KAIT) at Lick Observatory responded to Swift GRB 180620A (Evans et al., GCN 22798) starting at 08:37:19 UT, 141s after the burst. Observations were performed with an automatic sequence in the V, I, and clear (roughly R) filters, and the exposure time was 20 s per image, observations lasted about 3 hours. The optical afterglow (Evans et al., GCN 22790; Butler et al., GCN 22799; Elenin et al., GCN 22800; Tyurina et al., GCN 22801; Guidorzi et al., GCN 22803; Breeveld et al., GCN 22805; Watson et al., GCN 22806; Zhu et al., GCN 22811) was well detected in our V, I and clear filter images. A preliminary analysis shows that the afterglow rises at early time and peaked around 300s (also seen by Butler et al. GCN 22799; Watson et al., GCN 22806). After that the light curve shows monotonic decay, followed by a flat phase between ~1ks to ~3ks. A preliminary light curve is posted at: http://astro.berkeley.edu/~zwk/grb/GRB180620A/GRB180620A_kait.png
GCN Circular #22815
M. Stamatikos (OSU), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), P. A. Evans (U Leicester), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 180620A (trigger #843122) (Evans et al., GCN Circ. 22798). The BAT ground-calculated position is RA, Dec = 279.890, 23.239 deg which is
```
  RA(J2000)  =  18h 39m 33.5s 
  Dec(J2000) = +23d 14' 18.6" 
```
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 42%.
The mask-weighted light curve shows a multi-peaked structure that starts at ~T-7 s and ends at ~T+37 s. The two main peaks occur at ~T+5 s and ~T+12 s, respectively. T90 (15-350 keV) is 23.16 +- 4.82 sec (estimated error including systematics).
The time-averaged spectrum from T-6.92 to T+37.07 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.72 +- 0.05. The fluence in the 15-150 keV band is 5.8 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+4.47 sec in the 15-150 keV band is 7.7 +- 0.4 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/843122/BA/
GCN Circular #22818
Tassilo Schweyer and Patricia Schady (MPE Garching) report:
We observed the field of GRB 180620A (Swift trigger 843211; Evans et al., GCN #22807) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla Observatory (Chile).
Observations started at 04:35 UT on 2018-06-21, 20 hours after the GRB trigger. They were performed at an average seeing of 1.4" and at an average airmass of 1.7.
We detect a faint point source consistent with the position of the reported X-ray and optical afterglow (Elenin et al., GCN #22800; Osborne et al., GCN #22802; Breeveld et al., GCN #22805). Based on a total exposures time of around 30mins we estimate the following AB magnitudes:
```
g' = 23.9 +/- 0.1 mag
r' = 23.4 +/- 0.1 mag
i' = 23.1 +/- 0.1 mag
z' > 23.2 mag
J > 21.2 mag
H > 20.5 mag
K > 19.3 mag
```
Given magnitudes are calibrated against PanSTARRS and 2MASS field stars and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.11 in the direction of the burst (Schlafly & Finkbeiner 2011).
We thank Markus Rabus for the excellent support from La Silla.
GCN Circular #22824
D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, M. Ulanov, A. Tsvetkova, A. Lysenko, A. Kozlova, and T. Cline on behalf of the Konus-Wind team, report:
The long-duration GRB 180620A (Swift-BAT detection: Evans et al., GCN Cric. 22798) triggered Konus-Wind at T0=30906.173 s UT (08:35:06.173).
The burst light curve shows a multi-peaked structure which starts at ~T0-6.6 s and has a total duration of ~16 s. The emission is seen up to ~2 MeV.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB180620_T30906/
As observed by Konus-Wind, the burst had a fluence of 9.80(-1.02,+1.74)x10^-6 erg/cm2, and a 64-ms peak flux, measured from T0+7.504 s, of 2.69(-0.82,+0.94)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst (measured from T0 to T0+8.448 s) is best fit in the 20 keV - 4 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -1.19(-0.14,+0.16), the high energy photon index beta = -3.09(-6.91,+0.63), the peak energy Ep = 164(-24,+29) keV (chi2 = 70/75 dof).
All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.
GCN Circular #22826
M. Nakamura, T. Sakamoto (AGU)
We observed the field of GRB 180620A detected by Swift (Evans et al., GCN Circ. 22798) with the iTelescope.Net (http://www.itelescope.net) T11 (Planewave 20") telescope located at the New Mexico Skies Observatory (NM, USA). 20 images of 60 sec exposures were taken in the R filter starting from June 20 on 10:11:01 (UT) about 1.6 hours after the trigger and stopped on 10:44:55 (UT). Due to the tracking issue of the telescope, we only obtained nine good quality images.
We do not detect the optical afterglow both in the individual images and the stacked image at the UVOT position (Evans et al., GCN Circ. 22798). The estimated five sigma upper limit of the combined image (total exposure of 540 sec) is ~18.1 using the USNO-B1 catalog.
GCN Circular #22843
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 180620A, which was also detected by Swift (Evans P. A. et al., GCN 22798) and Konus-Wind (D. Svinkin D. et al., GCN 22824).
The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks of emission with strongest peak at 08:35:08.5 UT. The measured peak count rate is 287.9 cts/s above the background in combined data of four quadrants, with a total of 2046 cts. The local mean background count rate was 503 cts/s. Using cumulative rates, we measure a T90 of 14.8 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 #25671
V. Cunningham (U of Maryland), J. D. Neill (Caltech), S. B. Cenko (NASA GSFC), and R. Walters (Caltech) report on behalf of the SEDM team:
We observed the optical counterpart to GRB 180620A (Evans, et al., GCN 22798) with the Spectral Energy Distribution Machine (SEDM) on the 60 inch telescope at Palomar Observatory. The SEDM is a low resolution (R ~ 100) integral field unit spectrometer with a multi- band (ugri) rainbow camera imager (see Blagorodnova et al. 2018, PASP, 130, 035003, and Rigault et al. 2019, A&A, 627, A115).
The SEDM began observing the optical counterpart at 9:37:37 UTC (63 minutes after the burst trigger time). We performed 2 x 1200 s exposures over the wavelength range 3800-9200 A. The continuum emission is well-fit by a power law spectrum with index alpha = 1.4 (f_nu ~ nu^-alpha). We do not confidently identify any obvious emission or absorption features in the spectrum.

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Jochen Greiner, last update: 06-Sep-2019 [Disclaimer]