Gamma-ray Burst 180618A

(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:     Mon 18 Jun 18 00:43:25 UT
NOTICE_TYPE:     Swift-BAT GRB Position 
TRIGGER_NUM:     842475,   Seg_Num: 0   
GRB_RA:          169.937d {+11h 19m 45s} (J2000),
                 170.234d {+11h 20m 56s} (current),
                 169.120d {+11h 16m 29s} (1950)
GRB_DEC:         +73.848d {+73d 50' 52"} (J2000),
                 +73.747d {+73d 44' 48"} (current),
                 +74.122d {+74d 07' 18"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       785 [cnts]    Image_Peak=96 [image_cnts]
TRIGGER_DUR:     0.064 [sec]   
TRIGGER_INDEX:   10427     E_range: 50-350 keV
BKG_INTEN:       21035 [cnts]
BKG_TIME:        2578.87 SOD {00:42:58.87} UT
BKG_DUR:         8 [sec]
GRB_DATE:        18287 TJD;   169 DOY;   18/06/18
GRB_TIME:        2592.95 SOD {00:43:12.95} UT
GRB_PHI:          20.64 [deg]
GRB_THETA:        29.80 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     43.84 [sigma]
IMAGE_SIGNIF:    9.55 [sigma]
MERIT_PARAMS:     +1  +0  +0  -4  +3  +0  +0  +0 -41  +0
SUN_POSTN:        86.48d {+05h 45m 55s}  +23.40d {+23d 23' 48"}
SUN_DIST:         65.85 [deg]   Sun_angle= -5.6 [hr] (East of Sun)
MOON_POSTN:      148.08d {+09h 52m 19s}  +14.54d {+14d 32' 06"}
MOON_DIST:        60.54 [deg]
MOON_ILLUM:      24 [%]
GAL_COORDS:      131.28, 41.76 [deg] galactic lon,lat of the burst (or transient)      
ECL_COORDS:      122.70, 59.53 [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 = 238.19,17.92 [deg].

GCN NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Mon 18 Jun 18 00:43:54 UT
NOTICE_TYPE:    INTEGRAL SPI ACS Trigger
TRIGGER_NUM:    8077,   Sub_Num: 0
GRB_INTEN:      11.41 [sigma]  
GRB_TIME:       2591.02 SOD {00:43:11.02} UT
GRB_DATE:       18287 TJD;   169 DOY;   18/06/18
COMMENTS:       INTEGRAL SPI_ACS GRB Trigger.
COMMENTS:       Time_Scale=2.0000 and Time_Error=1.0000.
COMMENTS:
COMMENTS:       NOTE: This SPIACS event is temporally(1.0<100sec) coincident with the SWIFT_BAT event (trignum=842475).
COMMENTS:
COMMENTS:       The SPIACS lightcurve can be found at:
COMMENTS:       ftp://isdcarc.unige.ch/arc/FTP/ibas/spiacs/2018-06/2018-06-18T00-43-10.8798-19754-19344-0.lc

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 18 Jun 18 00:45:05 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     842475,   Seg_Num: 0
GRB_RA:          169.9415d {+11h 19m 45.9s} (J2000),
                 170.2388d {+11h 20m 57.3s} (current),
                 169.1250d {+11h 16m 29.9s} (1950)
GRB_DEC:         +73.8358d {+73d 50' 08.8"} (J2000),
                 +73.7346d {+73d 44' 04.4"} (current),
                 +74.1096d {+74d 06' 34.4"} (1950)
GRB_ERROR:       5.4 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       51 [cnts]
IMG_START_DATE:  18287 TJD;   169 DOY;   18/06/18
IMG_START_TIME:  2670.57 SOD {00:44:30.57} UT,   77.6 [sec] since BAT Trigger Time
CENTROID_X:      357.73,  raw= 358  [pixels]
CENTROID_Y:      335.75,  raw= 336  [pixels]
ROLL:            270.54 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   88.05
GRB_POS_XRT_Z:   121.01
IMAGE_URL:       sw00842475000msxps_rw.img
SUN_POSTN:        86.48d {+05h 45m 55s}  +23.40d {+23d 23' 48"}
SUN_DIST:         65.85 [deg]   Sun_angle= -5.6 [hr] (East of Sun)
MOON_POSTN:      148.10d {+09h 52m 23s}  +14.53d {+14d 31' 51"}
MOON_DIST:        60.53 [deg]
MOON_ILLUM:      24 [%]
GAL_COORDS:      131.29, 41.77 [deg] galactic lon,lat of the burst
ECL_COORDS:      122.72, 59.53 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 18 Jun 18 00:44:55 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     842475,   Seg_Num: 0
GRB_RA:          169.9415d {+11h 19m 45.95s} (J2000),
                 170.2388d {+11h 20m 57.32s} (current),
                 169.1250d {+11h 16m 29.99s} (1950)
GRB_DEC:         +73.8358d {+73d 50' 08.8"} (J2000),
                 +73.7346d {+73d 44' 04.4"} (current),
                 +74.1096d {+74d 06' 34.4"} (1950)
GRB_ERROR:       5.4 [arcsec radius, statistical plus systematic, 90% containment]    
GRB_INTEN:       1.27e-09 [erg/cm2/sec]
GRB_SIGNIF:      7.14 [sigma]
IMG_START_DATE:  18287 TJD;   169 DOY;   18/06/18
IMG_START_TIME:  2670.57 SOD {00:44:30.57} UT,   77.6 [sec] since BAT Trigger Time
TAM[0-3]:        327.67 237.16 261.67 243.68
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:        86.48d {+05h 45m 55s}  +23.40d {+23d 23' 48"}
SUN_DIST:         65.85 [deg]   Sun_angle= -5.6 [hr] (East of Sun)
MOON_POSTN:      148.09d {+09h 52m 23s}  +14.53d {+14d 31' 53"}
MOON_DIST:        60.53 [deg] 
MOON_ILLUM:      24 [%] 
GAL_COORDS:      131.29, 41.77 [deg] galactic lon,lat of the burst
ECL_COORDS:      122.72, 59.53 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.
COMMENTS:        The XRT position is 0.73 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 18 Jun 18 00:45:08 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     842475,   Seg_Num: 0
GRB_RA:          169.9415d {+11h 19m 45.9s} (J2000),
                 170.2388d {+11h 20m 57.3s} (current),
                 169.1250d {+11h 16m 29.9s} (1950)
GRB_DEC:         +73.8358d {+73d 50' 08.8"} (J2000),
                 +73.7346d {+73d 44' 04.4"} (current),
                 +74.1096d {+74d 06' 34.4"} (1950)
GRB_ERROR:       5.4 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       51 [cnts]
IMG_START_DATE:  18287 TJD;   169 DOY;   18/06/18
IMG_START_TIME:  2670.57 SOD {00:44:30.57} UT,   77.6 [sec] since BAT Trigger Time
CENTROID_X:      357.73,  raw= 358  [pixels]
CENTROID_Y:      335.75,  raw= 336  [pixels]
ROLL:            270.54 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   88.05
GRB_POS_XRT_Z:   121.01
IMAGE_URL:       sw00842475000msxps_rw.img
SUN_POSTN:        86.48d {+05h 45m 55s}  +23.40d {+23d 23' 48"}
SUN_DIST:         65.85 [deg]   Sun_angle= -5.6 [hr] (East of Sun)
MOON_POSTN:      148.10d {+09h 52m 23s}  +14.53d {+14d 31' 51"}
MOON_DIST:        60.53 [deg]
MOON_ILLUM:      24 [%]
GAL_COORDS:      131.29, 41.77 [deg] galactic lon,lat of the burst
ECL_COORDS:      122.72, 59.53 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 18 Jun 18 00:47:15 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     842475,   Seg_Num: 0
GRB_RA:          169.937d {+11h 19m 45s} (J2000),
                 170.234d {+11h 20m 56s} (current),
                 169.120d {+11h 16m 29s} (1950)
GRB_DEC:         +73.848d {+73d 50' 52"} (J2000),
                 +73.747d {+73d 44' 48"} (current),
                 +74.122d {+74d 07' 18"} (1950)
GRB_DATE:        18287 TJD;   169 DOY;   18/06/18
GRB_TIME:        2593.10 SOD {00:43:13.10} UT
TRIGGER_INDEX:   10427
GRB_PHI:          20.64 [deg]
GRB_THETA:        29.80 [deg]
DELTA_TIME:      17.00 [sec]
TRIGGER_DUR:     0.064 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     43.84 [sigma]
IMAGE_SIGNIF:    9.55 [sigma]
LC_URL:          sw00842475000msb.lc
SUN_POSTN:        86.48d {+05h 45m 55s}  +23.40d {+23d 23' 49"}
SUN_DIST:         65.85 [deg]   Sun_angle= -5.6 [hr] (East of Sun)
MOON_POSTN:      148.12d {+09h 52m 28s}  +14.53d {+14d 31' 31"}
MOON_DIST:        60.54 [deg]
MOON_ILLUM:      24 [%]
GAL_COORDS:      131.28, 41.76 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      122.70, 59.53 [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 = 238.19,17.92 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 18 Jun 18 00:47:31 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     842475,   Seg_Num: 0
POINT_RA:        169.822d {+11h 19m 17s} (J2000)
POINT_DEC:       +73.861d {+73d 51' 39"} (J2000)
POINT_ROLL:      270.539d
IMG_START_DATE:  18287 TJD;   169 DOY;   18/06/18
IMG_START_TIME:  2678.99 SOD {00:44:38.99} UT,   86.0 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.696
N_STARS:         21
X_OFFSET:        224 [pixels]
Y_OFFSET:        592 [pixels]
X_MAX:           1183 [pixels]
Y_MAX:           1551 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    7
SL_URL:          sw00842475000msufc0086.fits
SUN_POSTN:        86.48d {+05h 45m 55s}  +23.40d {+23d 23' 49"}
SUN_DIST:         65.82 [deg]   Sun_angle= -5.6 [hr] (East of Sun)
MOON_POSTN:      148.12d {+09h 52m 29s}  +14.52d {+14d 31' 29"}
MOON_DIST:        60.54 [deg]
MOON_ILLUM:      24 [%]
GAL_COORDS:      131.31, 41.73 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      122.64, 59.52 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 18 Jun 18 00:47:44 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     842475,   Seg_Num: 0
POINT_RA:        169.822d {+11h 19m 17s} (J2000)
POINT_DEC:       +73.861d {+73d 51' 39"} (J2000)
POINT_ROLL:      270.539d
IMG_START_DATE:  18287 TJD;   169 DOY;   18/06/18
IMG_START_TIME:  2678.99 SOD {00:44:38.99} UT,   86.0 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.696
N_STARS:         21
X_OFFSET:        224 [pixels]
Y_OFFSET:        592 [pixels]
X_MAX:           1183 [pixels]
Y_MAX:           1551 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    7
SL_URL:          sw00842475000msufc0086.fits
SUN_POSTN:        86.48d {+05h 45m 55s}  +23.40d {+23d 23' 49"}
SUN_DIST:         65.81 [deg]   Sun_angle= -5.6 [hr] (East of Sun)
MOON_POSTN:      148.12d {+09h 52m 29s}  +14.52d {+14d 31' 27"}
MOON_DIST:        60.54 [deg]
MOON_ILLUM:      24 [%]
GAL_COORDS:      131.31, 41.73 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      122.64, 59.52 [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:     Mon 18 Jun 18 00:48:17 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     842475,   Seg_Num: 0
POINT_RA:        169.822d {+11h 19m 17s} (J2000)
POINT_DEC:       +73.861d {+73d 51' 39"} (J2000)
ROLL:            270.539d
IMG_START_DATE:  18287 TJD;   169 DOY;   18/06/18
IMG_START_TIME:  2678.99 SOD {00:44:38.99} UT,   86.0 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     550975500
X_OFFSET:        495 [pixels]
Y_OFFSET:        846 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       655
Y_GRB_POS:       1006
BINNING_INDEX:   1
IM_URL:          sw00842475000msuni0108.fits
SUN_POSTN:        86.48d {+05h 45m 55s}  +23.40d {+23d 23' 49"}
SUN_DIST:         65.81 [deg]   Sun_angle= -5.6 [hr] (East of Sun)
MOON_POSTN:      148.13d {+09h 52m 31s}  +14.52d {+14d 31' 22"}
MOON_DIST:        60.54 [deg]
MOON_ILLUM:      24 [%]
GAL_COORDS:      131.31, 41.73 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      122.64, 59.52 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 18 Jun 18 00:48:27 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     842475,   Seg_Num: 0
POINT_RA:        169.822d {+11h 19m 17s} (J2000)
POINT_DEC:       +73.861d {+73d 51' 39"} (J2000)
ROLL:            270.539d
IMG_START_DATE:  18287 TJD;   169 DOY;   18/06/18
IMG_START_TIME:  2678.99 SOD {00:44:38.99} UT,   86.0 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     550975500
X_OFFSET:        495 [pixels]
Y_OFFSET:        846 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       655
Y_GRB_POS:       1006
BINNING_INDEX:   1
IM_URL:          sw00842475000msuni0108.fits
SUN_POSTN:        86.48d {+05h 45m 55s}  +23.40d {+23d 23' 49"}
SUN_DIST:         65.81 [deg]   Sun_angle= -5.6 [hr] (East of Sun)
MOON_POSTN:      148.13d {+09h 52m 31s}  +14.52d {+14d 31' 20"}
MOON_DIST:        60.54 [deg]
MOON_ILLUM:      24 [%]
GAL_COORDS:      131.31, 41.73 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      122.64, 59.52 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 18 Jun 18 00:49:32 UT
NOTICE_TYPE:     Swift-UVOT Position
TRIGGER_NUM:     842475,   Seg_Num: 0
GRB_RA:          169.9407d {+11h 19m 45.76s} (J2000),
                 170.2381d {+11h 20m 57.13s} (current),
                 169.1242d {+11h 16m 29.79s} (1950)
GRB_DEC:         +73.8370d {+73d 50' 13.2"} (J2000),
                 +73.7358d {+73d 44' 08.7"} (current),
                 +74.1108d {+74d 06' 38.7"} (1950)
GRB_ERROR:       1.1 [arcsec radius, statistical only]
GRB_MAG:         17.80 +/- 0.40 [mag]
FILTER:          10, White
IMG_START_DATE:  18287 TJD;   169 DOY;   18/06/18
IMG_START_TIME:  2675.00 SOD {00:44:35.00} UT,   82.1 [sec] since BAT Trigger Time
SUN_POSTN:        86.48d {+05h 45m 56s}  +23.40d {+23d 23' 49"}
SUN_DIST:         65.85 [deg]   Sun_angle= -5.6 [hr] (East of Sun)
MOON_POSTN:      148.14d {+09h 52m 34s}  +14.52d {+14d 31' 10"}
MOON_DIST:        60.54 [deg]
MOON_ILLUM:      24 [%]
GAL_COORDS:      131.29, 41.77 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      122.72, 59.53 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT UVOT Position Notice.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The UVOT position is 4.3 arcsec from the XRT position.  
COMMENTS:        Result based on srclist data.  
COMMENTS:        Notice generated automatically.

GCN Circular #22790
S. J. LaPorte (PSU), S. D. Barthelmy (GSFC), J. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), M. H. Siegel (PSU) and A. Tohuvavohu (PSU) report on behalf of the Neil Gehrels Swift Observatory Team:
At 00:43:13 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 180618A (trigger=842475). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 169.937, +73.848 which is
```
   RA(J2000) = 11h 19m 45s
   Dec(J2000) = +73d 50' 52"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single FRED structure with a duration of about 20 sec. The peak count rate was ~10000 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 00:44:30.5 UT, 77.6 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 169.9415, 73.8358 which is equivalent to:
```
   RA(J2000)  = +11h 19m 45.96s
   Dec(J2000) = +73d 50' 08.9"
```
with an uncertainty of 5.4 arcseconds (radius, 90% containment). This location is 44 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy.
The initial flux in the 2.5 s image was 1.27e-09 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 86 seconds after the BAT trigger. There is a candidate afterglow in the list of sources generated on-board at
```
  RA(J2000)  =	11:19:45.78 = 169.94074
  DEC(J2000) = +73:50:13.3  =  73.83704
```
with a 90%-confidence error radius of about 1.10 arc sec. This position is 4.5 arc sec. from the center of the XRT error circle. The estimated magnitude is 17.81. No correction has been made for the expected extinction corresponding to E(B-V) of 0.07.
Burst Advocate for this burst is S. J. LaPorte (extragsam AT gmail.com). 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:     Mon 18 Jun 18 01:07:28 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     842475,   Seg_Num: 0
POINT_RA:        169.819d {+11h 19m 16s} (J2000)
POINT_DEC:       +73.860d {+73d 51' 35"} (J2000)
POINT_ROLL:      270.536d
IMG_START_DATE:  18287 TJD;   169 DOY;   18/06/18
IMG_START_TIME:  2890.92 SOD {00:48:10.92} UT,   298.0 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.551
N_STARS:         11
X_OFFSET:        175 [pixels]
Y_OFFSET:        526 [pixels]
X_MAX:           1134 [pixels]
Y_MAX:           1485 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw00842475000msufc0297.fits
SUN_POSTN:        86.49d {+05h 45m 59s}  +23.40d {+23d 23' 50"}
SUN_DIST:         65.81 [deg]   Sun_angle= -5.6 [hr] (East of Sun)
MOON_POSTN:      148.32d {+09h 53m 17s}  +14.47d {+14d 28' 24"}
MOON_DIST:        60.57 [deg]
MOON_ILLUM:      24 [%]
GAL_COORDS:      131.32, 41.73 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      122.64, 59.52 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 18 Jun 18 01:07:43 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     842475,   Seg_Num: 0
POINT_RA:        169.819d {+11h 19m 16s} (J2000)
POINT_DEC:       +73.860d {+73d 51' 35"} (J2000)
POINT_ROLL:      270.536d
IMG_START_DATE:  18287 TJD;   169 DOY;   18/06/18
IMG_START_TIME:  2890.92 SOD {00:48:10.92} UT,   298.0 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.551
N_STARS:         11
X_OFFSET:        175 [pixels]
Y_OFFSET:        526 [pixels]
X_MAX:           1134 [pixels]
Y_MAX:           1485 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw00842475000msufc0297.fits
SUN_POSTN:        86.49d {+05h 45m 59s}  +23.40d {+23d 23' 50"}
SUN_DIST:         65.81 [deg]   Sun_angle= -5.6 [hr] (East of Sun)
MOON_POSTN:      148.32d {+09h 53m 18s}  +14.47d {+14d 28' 22"}
MOON_DIST:        60.57 [deg]
MOON_ILLUM:      24 [%]
GAL_COORDS:      131.32, 41.73 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      122.64, 59.52 [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:     Mon 18 Jun 18 01:08:34 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     842475,   Seg_Num: 0
POINT_RA:        169.819d {+11h 19m 16s} (J2000)
POINT_DEC:       +73.860d {+73d 51' 35"} (J2000)
ROLL:            270.536d
IMG_START_DATE:  18287 TJD;   169 DOY;   18/06/18
IMG_START_TIME:  2890.92 SOD {00:48:10.92} UT,   298.0 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     550975712
X_OFFSET:        495 [pixels]
Y_OFFSET:        846 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       655
Y_GRB_POS:       1006
BINNING_INDEX:   1
IM_URL:          sw00842475000msuni0319.fits
SUN_POSTN:        86.50d {+05h 45m 59s}  +23.40d {+23d 23' 50"}
SUN_DIST:         65.81 [deg]   Sun_angle= -5.6 [hr] (East of Sun)
MOON_POSTN:      148.33d {+09h 53m 20s}  +14.47d {+14d 28' 14"}
MOON_DIST:        60.57 [deg]
MOON_ILLUM:      24 [%]
GAL_COORDS:      131.32, 41.73 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      122.64, 59.52 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 18 Jun 18 01:08:49 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     842475,   Seg_Num: 0
POINT_RA:        169.819d {+11h 19m 16s} (J2000)
POINT_DEC:       +73.860d {+73d 51' 35"} (J2000)
ROLL:            270.536d
IMG_START_DATE:  18287 TJD;   169 DOY;   18/06/18
IMG_START_TIME:  2890.92 SOD {00:48:10.92} UT,   298.0 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     550975712
X_OFFSET:        495 [pixels]
Y_OFFSET:        846 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       655
Y_GRB_POS:       1006
BINNING_INDEX:   1
IM_URL:          sw00842475000msuni0319.fits
SUN_POSTN:        86.50d {+05h 45m 59s}  +23.40d {+23d 23' 50"}
SUN_DIST:         65.81 [deg]   Sun_angle= -5.6 [hr] (East of Sun)
MOON_POSTN:      148.33d {+09h 53m 20s}  +14.47d {+14d 28' 12"}
MOON_DIST:        60.57 [deg]
MOON_ILLUM:      24 [%]
GAL_COORDS:      131.32, 41.73 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      122.64, 59.52 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 18 Jun 18 01:26:45 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     842475,   Seg_Num: 0
GRB_RA:          169.9397d {+11h 19m 45.52s} (J2000),
                 170.2371d {+11h 20m 56.89s} (current),
                 169.1231d {+11h 16m 29.55s} (1950)
GRB_DEC:         +73.8365d {+73d 50' 11.4"} (J2000),
                 +73.7353d {+73d 44' 06.9"} (current),
                 +74.1103d {+74d 06' 36.9"} (1950)
GRB_ERROR:       3.6 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  18287 TJD;   169 DOY;   18/06/18
IMG_START_TIME:  2988.00 SOD {00:49:48.00} UT,   395.1 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:        86.51d {+05h 46m 02s}  +23.40d {+23d 23' 51"}
SUN_DIST:         65.84 [deg]   Sun_angle= -5.6 [hr] (East of Sun)
MOON_POSTN:      148.51d {+09h 54m 03s}  +14.42d {+14d 25' 25"}
MOON_DIST:        60.59 [deg]
MOON_ILLUM:      24 [%]
GAL_COORDS:      131.29, 41.77 [deg] galactic lon,lat of the burst
ECL_COORDS:      122.72, 59.53 [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:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.11% < P(seren) < 0.58%.

GCN Circular #22791
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team.
Using 1241 s of XRT Photon Counting mode data and 1 UVOT images for GRB 180618A, 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 = 169.94141, +73.83731 which is equivalent to:
```
RA (J2000): 11h 19m 45.94s
Dec (J2000): +73d 50' 14.3"
```
with an uncertainty of 1.7 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 #22792
C. Guidorzi (U. Ferrara), S. Kobayashi (LJMU), C.G. Mundell (U. Bath), A. Gomboc (U. Nova Gorica), I.A. Steele (LJMU) on behalf of a large collaboration report:
The 2-m Liverpool Telescope automatically began observing Swift GRB 180618A (LaPorte et al. GCN 22790) on June 18, 00:46:30 UT (197 s since the GRB trigger time) with the RINGO3 polarimeter and the IO:O camera in the SDSS-R filter. The optical counterpart identified by Swift-UVOT is clearly detected with r'=19.36 +- 0.05 mag in a 6x10s exposure at a mid time of 36.3 minutes post GRB, as calibrated against nearby SDSS objects.
GCN Circular #22793
V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), D.N. Burrows (PSU), A. Tohuvavohu (PSU), S. J. LaPorte (PSU), P.A. Evans (U. Leicester), S.L. Gibson (U. Leicester), Z. Liu (NAOC / U. Leicester) and S.J. LaPorte report on behalf of the Swift-XRT team:
We have analysed 7.8 ks of XRT data for GRB 180618A (LaPorte et al. GCN Circ. 22790), from 83 s to 24.6 ks after the BAT trigger. The data comprise 293 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Goad et al. (GCN Circ. 22791).
The light curve can be modelled with an initial power-law decay with an index of alpha=0.66 (+0.19, -0.31), followed by a break at T+158 s to an alpha of 1.80 (+/-0.05).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.91 (+/-0.09). The best-fitting absorption column is 2.0 (+0.4, -0.3) x 10^21 cm^-2, in excess of the Galactic value of 4.4 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 2.23 (+0.22, -0.21) and a best-fitting absorption column of 2.9 (+0.8, -0.7) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.3 x 10^-11 (5.4 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     2.9 (+0.8, -0.7) x 10^21 cm^-2
Galactic foreground: 4.4 x 10^20 cm^-2
Excess significance: 5.3 sigma
Photon index:	     2.23 (+0.22, -0.21)
```
If the light curve continues to decay with a power-law decay index of 1.80, the count rate at T+24 hours will be 1.9 x 10^-4 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.4 x 10^-15 (1.1 x 10^-14) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00842475.
This circular is an official product of the Swift-XRT team.
GCN Circular #22794
R. Hamburg (UAH) and E. Bissaldi (Politecnico & INFN Bari) report on behalf of the Fermi GBM Team:
"At 00:43:13.11 UT on 18 June 2018, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 180618A (trigger 550975398 / 180618030), which was also detected by the Swift/BAT (LaPorte et al. 2018, GCN 22790). The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 103 degrees.
The GBM light curve shows one main peak with a duration (T90) of about 3.7 s (50-300 keV). LaPorte et al. 2018 report a longer duration of ~20 s in the Swift/BAT. Given the soft tail following the initial hard spike, we suggest the discrepancy may be due to extended emission of this short GRB.
The time-averaged spectrum from T0 to T0+1.8 s is adequately fit a power law function with an exponential high-energy cutoff. The power law index is 1.08 +/- 0.06 and the cutoff energy, parameterized as Epeak, is 2.8 +/- 0.8 MeV.
The event fluence (10-1000 keV) in this time interval is (2.12 +/- 0.12)E-06 erg/cm^2. The 64-ms peak photon flux measured starting from T0 in the 10-1000 keV band is 14.6 +/- 1.9 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN Circular #22796
T. Sakamoto (AGU), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF/USRA), S. J. LaPorte (PSU), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), J. P. Norris (BSU), D. M. Palmer (LANL), M. Stamatikos (OSU), 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 180618A (trigger #842475) (LaPorte et al., GCN Circ. 22790). The BAT ground-calculated position is RA, Dec = 169.948, 73.825 deg which is
```
  RA(J2000)  =  11h 19m 47.6s
  Dec(J2000) = +73d 49' 29.3"
```
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 70%.
The mask-weighted light curve shows a short multi-peaked structure from ~ T0 to ~T+0.3, followed by some extended emission that lasts till ~T+50 s. T90 (15-350 keV) is 47.4 +- 11.1 sec (estimated error including systematics).
The time-averaged spectrum from T-0.06 to T+56.33 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.39 +- 0.27. The fluence in the 15-150 keV band is 6.7 +- 1.0 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T-0.08 sec in the 15-150 keV band is 2.2 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
The structure of the burst shows similarity to those of short GRBs with extended emission, as mentioned in Hamburg et al., GCN Circ. 22794. We thus perform further analysis on the short spike and the extended emission.
The spectrum of the short multi-peaked structure from T-0.056 to T+0.264 sec is best fit by a simple power-law model, with power-law index of 0.60 +- 0.24 and fluence (15-150 keV) of 1.3 +- 0.2 x 10^-7 erg/cm2. The spectrum of the extended emission from T+0.264 to T+56.328 sec is best fit by a simple power-law model, with power-law index of 1.53 +- 0.31 and fluence (15-150 keV) of 5.5 +- 1.0 x 10^-7 erg/cm2. These values are consistent with those of short GRBs with extended emission (Lien & Sakamoto et al. 2016).
Using a 4-ms binned light curve, the lag analysis of the first two tallest pulses (from ~T0 to ~T+0.1 s) finds a lag of 0.7 +/- 0.9 ms for the 100-350 keV to 25-50 keV band, and 1.5 (+1.8, -1.2) ms for the 50-100 keV to 15-25 keV band. Therefore, the lag values of these short pulses are consistent with those of short GRBs.
The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/842475/BA/
GCN Circular #22797
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-Kislovodsk robotic telescope (MASTER-Net: http://observ.pereplet.ru Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) , located in Kislovodsk Solar Station of Pulkovo observatory, was pointed to the Swift GRB180618A (LaPorte et al. GCN #22790; Sakamoto et al., GCN #22796) 25 sec after notice time and 41 sec after trigger time at 2018-06-18 00:43:53 UT. On our first (10s exposure) polarization set we haven`t found optical transient within SWIFT error-box (ra=169.933 dec=73.8478 r=0.05). The 5-sigma upper limit has been about 15.2 mag
The observations made on zenit distance = 61 degrees, galaxy latitude b = 42 degree. The moon (24 % bright part) below the horizon (The altitude of the Moon is -31 degree ). Observations started at twilight and bad transparency. The sun altitude is -6.8 degree.
MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in IAC was pointed to the GRB180618A 1734 sec after trigger time at 2018-06-18 01:12:07 UT. On our first (180s exposure) set we found ~19 mag optical transient within SWIFT UVOT error-box (LaPorte et al. GCN #22790; Guidorzi et al., GCN #22792;). The 5-sigma upper limit has been about 19.0 mag on single (180 s) and 20.5 on coadd (1800 s) exposures.
====================================================================
The observations made on zenit distance = 64 degrees, galaxy latitude b = 42 degree. The moon (24 % bright part) below the horizon (The altitude of the Moon is -15 degree ). The sun altitude is -38.3 degree. The object can be observed till sunrise at 2018-06-18 06:08:21 The message may be cited.
GCN Circular #22804
Z.P. Zhu, D. Xu, J.B. Zhang (NAOC), X. Zhang, J.H. Liu (XAO), Z.B. Dai (YNAO) report:
We observed the field of GRB 180618A (LaPorte et al., GCN 22790) using the 2.16-m telescope located at Xinglong, Hebei, China, equipped with the BFOSC camera. We obtained 6x600s R-band frames, starting at 12:43:22 UT on 2018-06-19, i.e., 1.50 days after the BAT trigger.
The previously detected optical afterglow of the GRB (e.g., LaPorte et al., GCN 22790; Guidorzi et al., GCN 22792; Tyurina et al., GCN 22797) was not present in our stacked image, down to a limiting magnitude of R~21.4 mag, calibrated with the SDSS field.
GCN Circular #22809
E. Mazaeva (IKI), A. Kusakin (FAPHI), A. Pozanenko (IKI), I. Reva (FAPHI), A. Volnova (IKI), M. Krugov (FAPHI) report on behalf of larger GRB follow-up collaboration:
We observed the field of GRB GRB 180618A (LaPorte et al., GCN 22790) with Zeiss-1000 1-m telescope of Tien Shan Astronomical Observatory starting on June 18 (UT) 15:39:19. We obtained several images in R-filter. The optical afterglow (LaPorte et al., GCN 22790; Guidorzi et al., GCN 22792; Tyurina et al., GCN 22797) is not detected in a stacked image. Preliminary photometry of the field is following.
```
Date        UT start t-T0     Filter Exp.    OT   Err.   UL
                      (mid, days)     (s)

2018-06-18  15:39:19 0.65209  R      36*120  n/d  n/d    22.2
```
The photometry is based on several nearby SDSS-DR10 stars.
Ref.stars
```
SDSS_id             R(Lupton)
J112037.79+735136.8 17.37
J111905.28+734733.2 17.54
J111907.19+734657.8 17.04
```

GCN Circular #22810
M. H. Siegel (PSU) and S. J. LaPorte (PSU) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 180618A 86 s after the BAT trigger (LaPorte et al., GCN Circ. 22790). We confirm the previously reported fading optical afterglow, also detected by LT (Guidorzi et al., GCN Circ. 22792) and MASTER (Tyurina et al., GCN Circ. 22797). We find that the source had faded away completely by the second orbit. The detection of the afterglow in six of UVOT's filters places an upper limit on the redshift of z < 1.2.
The preliminary UVOT position is:

    RA  (J2000) =  11:19:45.84 = 169.94102 (deg.)
    Dec (J2000) = +73:50:13.5  =  73.83707 (deg.)

with an estimated uncertainty of 0.43 arc sec. (radius, 90% confidence).
Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white (fc)          86          236          147         17.46 +/- 0.04
white               86         1544          390         17.95 +/- 0.03
white             5680         7315          393        >21.09
v                  628         1596          117         18.71 +/- 0.22
v                 6090         6290          196        >19.25
b                  553         1175           58         18.84 +/- 0.16
b                 5475         7110          393        >20.39
u (fc)             298          548          246         17.50 +/- 0.06
u                  298         1497          313         17.62 +/- 0.06
u                 5270         6905          393        >19.94
w1                 676         1472           97         18.59 +/- 0.24
w1                5065         6700          393        >19.63
m2                1254         1621           58        >17.6
w2                 604         1398           97         18.85 +/- 0.28

The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.07 in the direction of the burst (Schlegel et al. 1998).

GCN Circular #22822
Konus-Wind observation of GRB 180618A (a short GRB with extended emission)
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 bright, short-duration, hard GRB 180618A (Swift-BAT detection: LaPorte et al., GCN Circ 22790; Fermi-GBM detection: Hamburg et al., GCN Circ 22794) triggered Konus-Wind at T0=2591.201 s UT (00:43:11.201).
The burst light curve shows a bright multi-peaked initial pulse with a total duration of ~0.250 s, followed by an extended emission seen up to ~T0+10 s. The emission of the initial pulse is seen up to ~10 MeV.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB180618_T02591/
As observed by Konus-Wind, the burst had a fluence of 6.24(-1.13,+1.20)x10^-6 erg/cm2, and a 16-ms peak flux, measured from T0-0.010 s, of 5.60(-1.83,+1.88)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the initial pulse (measured from T0 to T0+0.192 s) is best fit in the 20 keV - 10 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.36(-0.24,+0.30) and Ep = 2461(-565,+788) keV (chi2 = 47/38 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.4 (chi2 = 47/37 dof).
The time-averaged spectrum of the extended emission (measured from T0+0.256 to T0+8.448 s) is best fit in the 20 keV - 2 MeV range by the CPL model with alpha = -0.68(-0.79,+1.59), Ep = 170(-66,+203) keV (chi2 = 102/98 dof).
Among ~300 bursts from the Konus catalog of short GRBs (Svinkin et al., 2016, ApJS 224, 10), GRB 180618A is within top 1% in the terms of 16-ms peak energy flux and within top 15% in the terms of the total energy fluence, both in the 20 keV - 10 MeV range. In the terms of Epeak, the burst is within 1% hardest GRBs in the sample.
All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.
GCN Circular #22842
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 short GRB 180618A, which was also detected by Swift (LaPorte S. J. et al., GCN 22790), Fermi-GBM (Hamburg R. et al., GCN 22794), Konus-Wind (Svinkin D. et al., GCN 22822).
The source was clearly detected in the 40-200 keV energy range. The light curve shows a single peak of emission with peak at 00:43:13.5 UT. The measured peak count rate is 217.1 cts/s above the background in combined data of four quadrants, with a total of 140.9 cts. The local mean background count rate was 456.9 cts/s. Using cumulative rates, we measure a T90 of 2.1 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.
Redshift z=0.554+-0.001
from host-galaxy spectroscopy: Jordana-Mitjans et al. 2022, ApJ, 939, 106

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