Gamma-ray Burst 201020A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 20 Oct 20 05:48:41 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1000926,   Seg_Num: 0
GRB_RA:          261.246d {+17h 24m 59s} (J2000),
                 261.443d {+17h 25m 46s} (current),
                 260.774d {+17h 23m 06s} (1950)
GRB_DEC:         +31.425d {+31d 25' 30"} (J2000),
                 +31.407d {+31d 24' 27"} (current),
                 +31.468d {+31d 28' 06"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       0 [cnts]    Image_Peak=2371 [image_cnts]
TRIGGER_DUR:     64.000 [sec] 
TRIGGER_INDEX:   20000     E_range: 15-50 keV
BKG_INTEN:       0 [cnts]
BKG_TIME:        0.00 SOD {00:00:00.00} UT
BKG_DUR:         0 [sec]
GRB_DATE:        19142 TJD;   294 DOY;   20/10/20
GRB_TIME:        20846.16 SOD {05:47:26.16} UT
GRB_PHI:           1.48 [deg]
GRB_THETA:        26.26 [deg]
SOLN_STATUS:     0x20000013
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    12.20 [sigma]
MERIT_PARAMS:     +1  +0  +0  +6  +1  +1  +0  +0 -37  +0 
SUN_POSTN:       205.34d {+13h 41m 22s}  -10.51d {-10d 30' 40"}
SUN_DIST:         68.10 [deg]   Sun_angle= -3.7 [hr] (East of Sun)
MOON_POSTN:      253.90d {+16h 55m 35s}  -21.93d {-21d 55' 40"}
MOON_DIST:        53.82 [deg]
MOON_ILLUM:      16 [%]
GAL_COORDS:       54.94, 31.16 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      257.09, 54.47 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Coordinates.  
COMMENTS:        This is an image trigger.  (The RATE_SIGNIF & BKG_{INTEN, TIME, DUR} are undefined.)  
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 = 183.56,19.19 [deg].  
COMMENTS:           
COMMENTS:        NOTE: This BAT event is temporally(19.0<100sec) coincident with the FERMI_GBM event (trignum=624865670).

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Tue 20 Oct 20 05:48:09 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      45
TRIGGER_NUM:     624865670
GRB_RA:          250.067d {+16h 40m 16s} (J2000),
                 250.282d {+16h 41m 08s} (current),
                 249.550d {+16h 38m 12s} (1950)
GRB_DEC:         +25.350d {+25d 21' 00"} (J2000),
                 +25.311d {+25d 18' 39"} (current),
                 +25.446d {+25d 26' 46"} (1950)
GRB_ERROR:       29.07 [deg radius, statistical plus systematic]
GRB_INTEN:       45 [cnts/sec]
DATA_SIGNIF:     4.50 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        19142 TJD;   294 DOY;   20/10/20
GRB_TIME:        20865.18 SOD {05:47:45.18} UT
GRB_PHI:          37.00 [deg]
GRB_THETA:        75.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      0.00
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:     100%  Unreliable location
2nd_MOST_LIKELY:   0%  n/a
DETECTORS:       0,1,0, 0,0,1, 0,0,0, 0,0,0, 0,0,
SUN_POSTN:       205.34d {+13h 41m 22s}  -10.51d {-10d 30' 39"}
SUN_DIST:         56.55 [deg]   Sun_angle= -3.0 [hr] (East of Sun)
MOON_POSTN:      253.89d {+16h 55m 34s}  -21.93d {-21d 55' 36"}
MOON_DIST:        47.37 [deg]
MOON_ILLUM:      16 [%]
GAL_COORDS:       44.67, 39.11 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      243.17, 46.95 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn201020241/quicklook/glg_lc_medres34_bn201020241.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 279.45,23.40 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 20 Oct 20 05:49:53 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     1000926,   Seg_Num: 0
POINT_RA:        261.230d {+17h 24m 55s} (J2000)
POINT_DEC:       +31.415d {+31d 24' 53"} (J2000)
IMG_START_DATE:  19142 TJD;   294 DOY;   20/10/20
IMG_START_TIME:  20987.69 SOD {05:49:47.69} UT,   141.5 [sec] since BAT Trigger Time
COUNTS:          33    Min_needed= 20
STD_DEV:         3.96   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        1    Max_iter_allowed= 4
ERROR_CODE:      3
COMMENTS:        SWIFT-XRT Nack Position.  
COMMENTS:        Standard deviation too large.

GCN NOTICE

 
TITLE:           GCN/SWIFT NOTICE 
NOTICE_DATE:     Tue 20 Oct 20 05:51:36 UT 
NOTICE_TYPE:     Swift-BAT GRB Lightcurve 
TRIGGER_NUM:     1000926,   Seg_Num: 0 
GRB_RA:          261.246d {+17h 24m 59s} (J2000), 
                 261.443d {+17h 25m 46s} (current), 
                 260.774d {+17h 23m 06s} (1950) 
GRB_DEC:         +31.425d {+31d 25' 30"} (J2000), 
                 +31.407d {+31d 24' 27"} (current), 
                 +31.468d {+31d 28' 06"} (1950) 
GRB_DATE:        19142 TJD;   294 DOY;   20/10/20 
GRB_TIME:        20846.16 SOD {05:47:26.16} UT 
TRIGGER_INDEX:   20000 
GRB_PHI:           1.48 [deg] 
GRB_THETA:        26.26 [deg] 
DELTA_TIME:      0.00 [sec] 
TRIGGER_DUR:     64.000 [sec]  
SOLN_STATUS:     0x13 
RATE_SIGNIF:     0.00 [sigma] 
IMAGE_SIGNIF:    12.20 [sigma] 
LC_URL:          sw01000926000msb.lc 
SUN_POSTN:       205.34d {+13h 41m 23s}  -10.51d {-10d 30' 42"} 
SUN_DIST:         68.10 [deg]   Sun_angle= -3.7 [hr] (East of Sun) 
MOON_POSTN:      253.93d {+16h 55m 43s}  -21.93d {-21d 56' 00"} 
MOON_DIST:        53.83 [deg] 
MOON_ILLUM:      16 [%] 
GAL_COORDS:       54.94, 31.16 [deg] galactic lon,lat of the burst (or transient) 
ECL_COORDS:      257.09, 54.47 [deg] ecliptic lon,lat of the burst (or transient) 
COMMENTS:        SWIFT-BAT GRB Lightcurve.
COMMENTS:        SWIFT-BAT GRB Lightcurve.   
COMMENTS:            
COMMENTS:        The next comments were copied from the BAT_POS Notice:   
COMMENTS:        This is an image 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 = 183.56,19.19 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 15 Oct 20 23:48:22 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1000452,   Seg_Num: 0
POINT_RA:        354.270d {+23h 37m 05s} (J2000)
POINT_DEC:       +53.416d {+53d 24' 56"} (J2000)
ROLL:            323.810d
IMG_START_DATE:  19137 TJD;   289 DOY;   20/10/15
IMG_START_TIME:  85430.62 SOD {23:43:50.62} UT,   3217.4 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     624498256
X_OFFSET:        573 [pixels]
Y_OFFSET:        1162 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       733
Y_GRB_POS:       1322
BINNING_INDEX:   1
IM_URL:          sw01000452000msuni3243.fits
SUN_POSTN:       201.36d {+13h 25m 26s}   -8.97d {-08d 58' 13"}
SUN_DIST:        130.49 [deg]   Sun_angle= -10.2 [hr] (East of Sun)
MOON_POSTN:      192.10d {+12h 48m 24s}   -0.04d {-00d 02' 34"}
MOON_DIST:       124.56 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:      111.87, -7.85 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       24.06, 49.50 [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:     Sat 17 Oct 20 09:52:15 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1000613,   Seg_Num: 0
POINT_RA:         36.644d {+02h 26m 34s} (J2000)
POINT_DEC:       +66.683d {+66d 41' 01"} (J2000)
POINT_ROLL:      16.304d
IMG_START_DATE:  19139 TJD;   291 DOY;   20/10/17
IMG_START_TIME:  35297.54 SOD {09:48:17.54} UT,   106.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.067
N_STARS:         127
X_OFFSET:        394 [pixels]
Y_OFFSET:        572 [pixels]
X_MAX:           1353 [pixels]
Y_MAX:           1531 [pixels]
DET_THRESH:      12
PHOTO_THRESH:    6
SL_URL:          sw01000613000msufc0106.fits
SUN_POSTN:       202.68d {+13h 30m 44s}   -9.49d {-09d 29' 23"}
SUN_DIST:        121.89 [deg]   Sun_angle= 11.0 [hr] (West of Sun)
MOON_POSTN:      211.89d {+14h 07m 33s}   -8.84d {-08d 50' 32"}
MOON_DIST:       121.96 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:      132.16,  5.53 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       61.38, 48.47 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 17 Oct 20 09:59:40 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1000613,   Seg_Num: 0
POINT_RA:         36.649d {+02h 26m 36s} (J2000)
POINT_DEC:       +66.683d {+66d 40' 57"} (J2000)
POINT_ROLL:      16.309d
IMG_START_DATE:  19139 TJD;   291 DOY;   20/10/17
IMG_START_TIME:  35455.57 SOD {09:50:55.57} UT,   264.3 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.525
N_STARS:         93
X_OFFSET:        154 [pixels]
Y_OFFSET:        332 [pixels]
X_MAX:           1593 [pixels]
Y_MAX:           1771 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw01000613000msufc0264.fits
SUN_POSTN:       202.69d {+13h 30m 45s}   -9.49d {-09d 29' 29"}
SUN_DIST:        121.89 [deg]   Sun_angle= 11.0 [hr] (West of Sun)
MOON_POSTN:      211.96d {+14h 07m 51s}   -8.87d {-08d 52' 22"}
MOON_DIST:       121.99 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:      132.16,  5.53 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       61.38, 48.47 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 20 Oct 20 05:54:08 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1000926,   Seg_Num: 0
POINT_RA:        261.230d {+17h 24m 55s} (J2000)
POINT_DEC:       +31.415d {+31d 24' 53"} (J2000)
ROLL:            241.488d
IMG_START_DATE:  19142 TJD;   294 DOY;   20/10/20
IMG_START_TIME:  20990.37 SOD {05:49:50.37} UT,   144.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     624865816
X_OFFSET:        696 [pixels]
Y_OFFSET:        963 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       856
Y_GRB_POS:       1123
BINNING_INDEX:   1
IM_URL:          sw01000926000msuni0170.fits
SUN_POSTN:       205.35d {+13h 41m 23s}  -10.51d {-10d 30' 45"}
SUN_DIST:         68.08 [deg]   Sun_angle= -3.7 [hr] (East of Sun)
MOON_POSTN:      253.95d {+16h 55m 49s}  -21.94d {-21d 56' 18"}
MOON_DIST:        53.81 [deg]
MOON_ILLUM:      16 [%]
GAL_COORDS:       54.93, 31.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      257.06, 54.46 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 20 Oct 20 05:53:54 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     1000926,   Seg_Num: 0
GRB_RA:          261.2294d {+17h 24m 55.05s} (J2000),
                 261.4260d {+17h 25m 42.23s} (current),
                 260.7571d {+17h 23m 01.69s} (1950)
GRB_DEC:         +31.4287d {+31d 25' 43.3"} (J2000),
                 +31.4112d {+31d 24' 40.4"} (current),
                 +31.4723d {+31d 28' 20.2"} (1950)
GRB_ERROR:       3.9 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  19142 TJD;   294 DOY;   20/10/20
IMG_START_TIME:  20995.00 SOD {05:49:55.00} UT,   148.8 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       205.35d {+13h 41m 23s}  -10.51d {-10d 30' 44"}
SUN_DIST:         68.09 [deg]   Sun_angle= -3.7 [hr] (East of Sun)
MOON_POSTN:      253.95d {+16h 55m 48s}  -21.94d {-21d 56' 17"}
MOON_DIST:        53.83 [deg]
MOON_ILLUM:      16 [%]
GAL_COORDS:       54.94, 31.18 [deg] galactic lon,lat of the burst
ECL_COORDS:      257.06, 54.47 [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 Circular #28696
E. Ambrosi (INAF-IASFPA), A. D'Ai (INAF-IASFPA), V. D'Elia (SSDC), N. J. Klingler (PSU), H. A. Krimm (NSF), A. Y. Lien (GSFC/UMBC), K. L. Page (U Leicester), T. Sakamoto (AGU), B. Sbarufatti (PSU) and A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift Observatory Team:
At 05:47:26 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 201020A (trigger=1000926). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 261.246, +31.425 which is
```
   RA(J2000) = 17h 24m 59s
   Dec(J2000) = +31d 25' 30"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single-peaked structure with a duration of about 20 sec. The peak count rate was ~1800 counts/sec (15-350 keV), at ~17 sec after the trigger.
The XRT began observing the field at 05:49:47.6 UT, 141.5 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source with an enhanced position: RA, Dec 261.2279, 31.4288 which is equivalent to:
```
   RA(J2000)  = 17h 24m 54.71s
   Dec(J2000) = +31d 25' 43.8"
```
with an uncertainty of 2.2 arcseconds (radius, 90% containment). This location is 57 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 https://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 3.70 x 10^20 cm^-2 (Willingale et al. 2013).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 144 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at
```
  RA(J2000)  =	17:24:54.67 = 261.22779
  DEC(J2000) = +31:25:42.0  =  31.42834
```
with a 90%-confidence error radius of about 0.62 arc sec. This position is 5.4 arc sec. from the center of the XRT error circle. The estimated magnitude is 18.14 with a 1-sigma error of about 0.15. No correction has been made for the expected extinction corresponding to E(B-V) of 0.04.
Burst Advocate for this burst is E. Ambrosi (elena.ambrosi AT inaf.it). 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/)

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 20 Oct 20 05:52:45 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1000926,   Seg_Num: 0
POINT_RA:        261.230d {+17h 24m 55s} (J2000)
POINT_DEC:       +31.415d {+31d 24' 53"} (J2000)
POINT_ROLL:      241.488d
IMG_START_DATE:  19142 TJD;   294 DOY;   20/10/20
IMG_START_TIME:  20990.37 SOD {05:49:50.37} UT,   144.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.647
N_STARS:         79
X_OFFSET:        377 [pixels]
Y_OFFSET:        644 [pixels]
X_MAX:           1336 [pixels]
Y_MAX:           1603 [pixels]
DET_THRESH:      11
PHOTO_THRESH:    5
SL_URL:          sw01000926000msufc0144.fits
SUN_POSTN:       205.35d {+13h 41m 23s}  -10.51d {-10d 30' 43"}
SUN_DIST:         68.08 [deg]   Sun_angle= -3.7 [hr] (East of Sun)
MOON_POSTN:      253.94d {+16h 55m 45s}  -21.94d {-21d 56' 09"}
MOON_DIST:        53.81 [deg]
MOON_ILLUM:      16 [%]
GAL_COORDS:       54.93, 31.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      257.06, 54.46 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 20 Oct 20 05:58:47 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1000926,   Seg_Num: 0
POINT_RA:        261.230d {+17h 24m 55s} (J2000)
POINT_DEC:       +31.413d {+31d 24' 46"} (J2000)
ROLL:            241.491d
IMG_START_DATE:  19142 TJD;   294 DOY;   20/10/20
IMG_START_TIME:  21148.36 SOD {05:52:28.36} UT,   302.2 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     624865974
X_OFFSET:        696 [pixels]
Y_OFFSET:        963 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       856
Y_GRB_POS:       1123
BINNING_INDEX:   1
IM_URL:          sw01000926000msuni0328.fits
SUN_POSTN:       205.35d {+13h 41m 24s}  -10.51d {-10d 30' 49"}
SUN_DIST:         68.08 [deg]   Sun_angle= -3.7 [hr] (East of Sun)
MOON_POSTN:      254.00d {+16h 56m 01s}  -21.95d {-21d 56' 52"}
MOON_DIST:        53.82 [deg]
MOON_ILLUM:      16 [%]
GAL_COORDS:       54.92, 31.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      257.06, 54.46 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 20 Oct 20 05:58:53 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1000926,   Seg_Num: 0
POINT_RA:        261.230d {+17h 24m 55s} (J2000)
POINT_DEC:       +31.413d {+31d 24' 46"} (J2000)
ROLL:            241.491d
IMG_START_DATE:  19142 TJD;   294 DOY;   20/10/20
IMG_START_TIME:  21148.36 SOD {05:52:28.36} UT,   302.2 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     624865974
X_OFFSET:        696 [pixels]
Y_OFFSET:        963 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       856
Y_GRB_POS:       1123
BINNING_INDEX:   1
IM_URL:          sw01000926000msuni0328.fits
SUN_POSTN:       205.35d {+13h 41m 24s}  -10.51d {-10d 30' 49"}
SUN_DIST:         68.08 [deg]   Sun_angle= -3.7 [hr] (East of Sun)
MOON_POSTN:      254.00d {+16h 56m 01s}  -21.95d {-21d 56' 52"}
MOON_DIST:        53.82 [deg]
MOON_ILLUM:      16 [%]
GAL_COORDS:       54.92, 31.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      257.06, 54.46 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 20 Oct 20 05:56:06 UT
NOTICE_TYPE:     Swift-UVOT Position
TRIGGER_NUM:     1000926,   Seg_Num: 0
GRB_RA:          261.2277d {+17h 24m 54.64s} (J2000),
                 261.4243d {+17h 25m 41.83s} (current),
                 260.7554d {+17h 23m 01.28s} (1950)
GRB_DEC:         +31.4283d {+31d 25' 41.8"} (J2000),
                 +31.4108d {+31d 24' 39.0"} (current),
                 +31.4719d {+31d 28' 18.8"} (1950)
GRB_ERROR:       0.6 [arcsec radius, statistical only]
GRB_MAG:         18.13 +/- 0.14 [mag]
FILTER:          10, White
IMG_START_DATE:  19142 TJD;   294 DOY;   20/10/20
IMG_START_TIME:  20987.00 SOD {05:49:47.00} UT,   140.8 [sec] since BAT Trigger Time
SUN_POSTN:       205.35d {+13h 41m 23s}  -10.51d {-10d 30' 46"}
SUN_DIST:         68.09 [deg]   Sun_angle= -3.7 [hr] (East of Sun)
MOON_POSTN:      253.98d {+16h 55m 54s}  -21.94d {-21d 56' 32"}
MOON_DIST:        53.83 [deg]
MOON_ILLUM:      16 [%]
GAL_COORDS:       54.94, 31.18 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      257.06, 54.47 [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 Genie data.  
COMMENTS:        Notice generated automatically.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 20 Oct 20 05:58:08 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     1000926,   Seg_Num: 0
GRB_RA:          261.2278d {+17h 24m 54.67s} (J2000),
                 261.4244d {+17h 25m 41.85s} (current),
                 260.7555d {+17h 23m 01.30s} (1950)
GRB_DEC:         +31.4287d {+31d 25' 43.3"} (J2000),
                 +31.4112d {+31d 24' 40.4"} (current),
                 +31.4723d {+31d 28' 20.2"} (1950)
GRB_ERROR:       2.2 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  19142 TJD;   294 DOY;   20/10/20
IMG_START_TIME:  20995.00 SOD {05:49:55.00} UT,   148.8 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       205.35d {+13h 41m 24s}  -10.51d {-10d 30' 48"}
SUN_DIST:         68.09 [deg]   Sun_angle= -3.7 [hr] (East of Sun)
MOON_POSTN:      254.00d {+16h 55m 59s}  -21.95d {-21d 56' 47"}
MOON_DIST:        53.83 [deg]
MOON_ILLUM:      16 [%]
GAL_COORDS:       54.94, 31.18 [deg] galactic lon,lat of the burst
ECL_COORDS:      257.06, 54.47 [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:     Tue 20 Oct 20 05:57:58 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1000926,   Seg_Num: 0
POINT_RA:        261.230d {+17h 24m 55s} (J2000)
POINT_DEC:       +31.413d {+31d 24' 46"} (J2000)
POINT_ROLL:      241.491d
IMG_START_DATE:  19142 TJD;   294 DOY;   20/10/20
IMG_START_TIME:  21148.36 SOD {05:52:28.36} UT,   302.2 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.431
N_STARS:         172
X_OFFSET:        137 [pixels]
Y_OFFSET:        404 [pixels]
X_MAX:           1576 [pixels]
Y_MAX:           1843 [pixels]
DET_THRESH:      6
PHOTO_THRESH:    2
SL_URL:          sw01000926000msufc0302.fits
SUN_POSTN:       205.35d {+13h 41m 24s}  -10.51d {-10d 30' 48"}
SUN_DIST:         68.08 [deg]   Sun_angle= -3.7 [hr] (East of Sun)
MOON_POSTN:      254.00d {+16h 55m 59s}  -21.95d {-21d 56' 46"}
MOON_DIST:        53.82 [deg]
MOON_ILLUM:      16 [%]
GAL_COORDS:       54.92, 31.17 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      257.06, 54.46 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN Circular #28697
R. Adachi, R. Hosokawa, K. L. Murata, M. Niwano, F. Ogawa, N. Nakamura, N. Ito, S. Ogata, H. Takamatsu, H. Hara, Y. Yatsu, and N. Kawai (TokyoTech) report on behalf of the MITSuME collaboration:
We observed the field of GRB 201020A (E. Ambrosi et al.,GCN Circular #28696) with the optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan. The observation started at 2020-10-20 08:31:00 UT. The first 28 images were heavily affected by twilight at Akeno Observatory. We detected the point source at the position consistent with the afterglow detected previously (E. Ambrosi et al. GCN #28696). We measured the magnitudes as follows.
```
T0+[min] MID-UT T-EXP[sec] measured magnitudes
------------------------------------------------------------------------------------------------
196 09:15:39 1260 g'=19.4+/-0.2, Rc=18.4+/-0.1, Ic=18.4+/-0.2
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
```
We used GSC2.3 and PS1 catalog for flux calibration. The magnitudes are expressed in the AB system. The images were processed in real-time through the MITSuME GPU reduction pipeline (Niwano et al., accepted for publication in PASJ, https://arxiv.org/abs/2008.11486; https://github.com/MNiwano/Eclaire).
GCN Circular #28698
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team.
Using 729 s of XRT Photon Counting mode data and 1 UVOT images for GRB 201020A, 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 = 261.22827, +31.42804 which is equivalent to:
```
RA (J2000): 17h 24m 54.78s
Dec (J2000): +31d 25' 40.9"
```
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 #28700
V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D.Kuvshinov, D. Cheryasov (Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA),
R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias),
D. Buckley (South African Astronomical Observatory),
O.A. Gres, N.M. Budnev, O.Ershova (Irkutsk State University, API),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
V. Yurkov, A. Gabovich, Yu. Sergienko (Blagoveschensk Educational State University)
MASTER-Tavrida robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, SAI Crimea astronomical station) was pointed to the Swift GRB 201020A ( E. Ambrosi et al., GCN 28696) errorbox 35426 sec after notice time and 35521 sec after trigger time at 2020-10-20 15:39:27 UT, with upper limit up to 17.6 mag. Observations started at twilight. The observations began at zenith distance = 32 deg. The sun altitude is -9.4 deg.
The galactic latitude b = 31 deg., longitude l = 55 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1464820
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

   35612 |      MASTER-Tavrida |   C |   180 | 16.4 |        
   36013 |      MASTER-Tavrida |   C |   180 | 17.6 |        
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
GCN Circular #28701
S.Y. Fu (NAOC), Z.P. Zhu (NAOC, HUST), X. Liu, D. Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:
We observed the field of GRB 201020A (Ambrosi et al., GCN 28696) using the NEXT-0.6m telescope located at Nanshan, Xinjiang, China. We obtained 15x120s frames in the Sloan r-band, starting at 13:48:25 UT on 2020-10-20, i.e., 8.02 hr after the BAT trigger.
The optical afterglow (Ambrosi et al., GCN 28696; Adachi et al., GCN 28697) of the burst is clearly detected in our stacked image, with r = 19.69 +/- 0.06 mag at T_mid = 0.3461 day post-burst, calibrated with nearby PS1 stars.
GCN Circular #28703
S. Belkin (IKI), A. Pozanenko (IKI), V. Kim (AFIF, Pulkovo Observatory), M. Krugov (AFIF), N. Pankov (HSE), A. Volnova (IKI) report on behalf of IKI GRB FuN:
We observed the filed of GRB 201020A (Ambrosi et al., GCN 28696) with AZT-20 telescope of Assy-Turgen observatory starting on (UT) Oct. 20 (Ut) 14:00:44 (UT) in r'-filter. We clearly detect optical afterglow (Ambrosi et al., GCN 28696; Adachi et al., GCN 28697; Fu et al., GCN 28701).
Preliminary photometry of the afterglow is following
```
Date       UT start  t-T0     Filter  Exp.    OT    Err.   UL (3sigma)
                      (mid, days)        (s)

2020-10-20 14:00:44  0.36688  r'(AB) 70*60    19.70 0.03   23.8
```
The photometry is based on the nearby stars of PanSTARRS-PS1 catalog.
```
SDSS-DR12_id        r
J172452.73+312623.9 18.459
J172455.96+312344.8 18.057
J172452.57+312302.1 17.618
J172456.76+312315.5 16.876
```
GCN Circular #28705
T. Sakamoto (AGU), E. Ambrosi (INAF-IASFPA), S. D. Barthelmy (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-60 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 201020A (trigger #1000926) (Ambrosi et al., GCN Circ.28696). The BAT ground-calculated position is RA, Dec = 261.239, 31.428 deg which is
```
  RA(J2000)  =  17h 24m 57.4s 
  Dec(J2000) = +31d 25' 41.8" 
```
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 90%.
The mask-weighted light curve shows a single symmetrical peak starting at ~T+8 sec, peaking at T+17 sec, and decaying to background by T+26 sec. T90 (15-350 keV) is 14.17 +- 4.68 sec (estimated error including systematics).
The time-averaged spectrum from T+8.23 to T+30.17 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.25 +- 0.14. The fluence in the 15-150 keV band is 9.2 +- 0.7 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+17.17 sec in the 15-150 keV band is 2.1 +- 0.2 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/1000926/BA/
GCN Circular #28706
E. Bissaldi (Politecnico and INFN Bari), C. Malacaria (NASA-MSFC/USRA) and C. Meegan (UAH) report on behalf of the Fermi GBM Team:
"At 05:47:45.18 UT on 20 October 2020, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 201020A (trigger 624865670 / 201020241), which was also detected by the Swift/BAT (Ambrosi et al. 2020, GCN 28696). The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 66 degrees.
The GBM light curve shows a single emission episode with a duration (T90) of about 22 s (50-300 keV). The time-averaged spectrum from T0-10.2s to T0+10.2 s is best fit by a simple power law function with index -1.83 +/- 0.04.
The event fluence (10-1000 keV) in this time interval is (2.47 +/- 0.17)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0-3.6 s in the 10-1000 keV band is 3.48 +/- 0.14 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html
For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"
GCN Circular #28707
A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), D.N. Burrows (PSU), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A. Melandri (INAF-OAB), T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB) and E. Ambrosi report on behalf of the Swift-XRT team:
We have analysed 6.9 ks of XRT data for GRB 201020A (Ambrosi et al. GCN Circ. 28696), from 148 s to 35.3 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. 28698).
The light curve can be modelled with a power-law decay with a decay index of alpha=0.71 (+/-0.04).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.06 (+0.18, -0.17). The best-fitting absorption column is 8.6 (+4.4, -3.9) x 10^20 cm^-2, in excess of the Galactic value of 3.7 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.2 x 10^-11 (3.9 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     8.6 (+4.4, -3.9) x 10^20 cm^-2
Galactic foreground: 3.7 x 10^20 cm^-2
Excess significance: 2.1 sigma
Photon index:	     2.06 (+0.18, -0.17)
```
If the light curve continues to decay with a power-law decay index of 0.71, the count rate at T+24 hours will be 0.015 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.7 x 10^-13 (5.7 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/01000926.
This circular is an official product of the Swift-XRT team.
GCN Circular #28708
N. Pankov (HSE), A. Pozanenko (IKI), V. Rumyantsev (CrAO), S. Belkin (IKI), A. Volnova (IKI) report on behalf of IKI GRB FuN:
We observed the GRB 201020A (Ambrosi et al., GCN 28696) with ZTSH 2.6m telescope of CrAO observatory starting on Oct. 20 (UT) 16:06:30. The optical afterglow (Ambrosi et al., GCN 28696; Adachi et al., GCN 28697; Fu et al., GCN 28701; Belkin et al., GCN 28703) is clearly detected in R filter. Preliminary photometry of the afterglow in a combined image is following
```
Date       UT start   t-T0    Filter Exp.     OT      err    UL(3sigma)
                      (mid, days)       (s)

2018-10-20 16:06:30   0.42991 R      30*120   20.00   0.10   21.5
```
The photometry is based on several nearby USNO-B1.0 (R2) stars.
GCN Circular #28711
H. Kumar(IITB), J. Stanzin (IIA), V. Bhalerao(IITB), G. C. Anupama(IIA), S. Barway(IIA), report on behalf of the GROWTH-India collaboration:
We followed up GRB 2010210A (E. Ambrosi et al., GCN #28696; also see:- R. Adachi et al., GCN #28697; J.P. Osborne et al., GCN #28698; V. Lipunov et al., GCN #27800, S.Y. Fu et al., GCN #28701; S. Belkin et al., GCN #28703 and T. Pankov et al., GCN #28708) with 0.7m GROWTH-India telescope. We obtained 300-sec exposures in the SDSS r’ filter starting at 2020-10-20T13:00:50.42 UT (~7.22 hrs after the burst). We clearly detected uncataloged sources at a position consistent with E. Ambrosi et al., GCN #28696. Here are the photometric results from GIT observations:-
```
------------------------------------------------------------------
 JD (END) | T_end-T0(hrs) | Filter | Mag |
------------------------------------------------------------------
2459143.04576 | 7.31 |  r  |  19.43 +/- 0.06
2459143.04943 | 7.39 |  r  |  19.49 +/- 0.05
2459143.05670 | 7.57 |  r  |  19.52 +/- 0.04
2459143.06046 | 7.66 |  r  |  19.59 +/- 0.04
2459143.06406 | 7.75 |  r  |  19.63 +/- 0.04
2459143.06764 | 7.83 |  r  |  19.65 +/- 0.04
-----------------------------------------------------------------
```
Combining our photometric results with r’ measurements of S.Y. Fu et al., (GCN #28701), S. Belkin et al., (GCN #28703), and T. Pankov et al., (GCN #28708) we conclude that the source is fading with a power-law index of 1.6 +/- 0.2. Given the fast fading, we encourage the follow-up of the source. The magnitudes are not corrected for galactic extinction.
The GROWTH India Telescope (GIT) is a 70-cm telescope with a 0.7 degree field of view, set up by the Indian Institute of Astrophysics and the Indian Institute of Technology Bombay with support from the Indo-US Science and Technology Forum (IUSSTF) and the Science and Engineering Research Board (SERB) of the Department of Science and Technology (DST), Government of India (https://sites.google.com/view/growthindia/). It is located at the Indian Astronomical Observatory (Hanle), operated by the Indian Institute of Astrophysics (IIA).
GCN Circular #28713
Gregory S.H. Paek (CEOU/SNU), Myungshin Im (CEOU/SNU), Taewoo Kim, and Wonseok Kang (DOAO) on behalf of a larger collaboration
We observed the optical counterpart of GRB 201020A (E. Ambrosi et al., GCN #28696; R. Adachi et al., GCN #28697; J.P. Osborne et al., GCN #28698; V. Lipunov et al., GCN #27800, S.Y. Fu et al., GCN #28701; S. Belkin et al., GCN #28703, T. Pankov et al., GCN #28708, and H. Kumar et al., GCN #28711) with the 1-m class telescope in Deokheung Optical Astronomy Observatory (DOAO). We calibrated flux with PS1 catalog and use AB magnitude system.
```
---------------------------------------------------------------------
Mid Date[UT] Mid t-t0[days] Filter Exp.time[s] Mag Error
---------------------------------------------------------------------
2020-10-20 10:28:07 0.195 V 300*3 19.361 0.059
2020-10-20 10:33:21 0.199 R 300*3 19.006 0.042
2020-10-20 10:38:35 0.202 I 300*3 18.767 0.039
```
t0 : 2020-10-20 05:47:26 UT (E. Ambrosi et al., GCN #28696)
The magnitudes are not corrected for galactic extinction.
GCN Circular #28717
D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), M. Blazek, J. F. Agui Fernandez, C. C. Thoene (all HETH/IAA-CSIC), G. Lombardi (GRANTECAN, IAC) and A. Tejero (GRANTECAN) report:
We observed the afterglow (Ambrosi et al., GCN#28696; Adachi et al., GCN#28697; Fu et al., GCN#28701; Belkin et al., GCN#28703; Pankov et al., GCN#28708; Kumar et al., GCN#28711; Paek et al., GCN#28713) of GRB 201020A (Ambrosi et al., GCN#28696; Sakamoto et al., GCN#28705; Bissaldi et al., GCN#28706) with the 10.4m GTC telescope, at Roque de los Muchachos Observatory (La Palma, Spain) equipped with OSIRIS. The observation started on 20 October 2020 at 20:08 UT (14.34 hrs after the GRB onset) and consisted of 4 x 900s with the R1000B grism, covering the wavelength range between 3700 and 7800 AA. Observations were taken under inclement conditions, with bad seeing and thick clouds passing through.
The spectrum shows a clear continuum, consistent with the Lyman forest, Ly-alpha, SiII, OI, CII, SiIV, CIV, FeII, FeII*, and AlII, all at a common redshift of z = 2.903, which we identify as the redshift of the GRB.
GCN Circular #28737
P. Gokuldass (UVI), R. Strausbaugh (UVI), N. Orange (OrangeWave Innovative Science, LLC), D. Morris (UVI), A. Cucchiara (UVI/College of Marin) report:
We observed the field of GRB201020A (Ambrosi et al., GCN 28696) with the 0.5m Virgin Island Robotic Telescope (VIRT) at the University of the Virgin Islands' Etelman Observatory on 10-20-2020 starting at 23:11:52.3 UT (T+17.2 hrs). We performed a series of exposures in R filter with a total exposure of 3140 s. The weather conditions were clear during the hours of observation with an average airmass of 2.1.
We find no new source within the enhanced XRT position error circle (Osborne et al., 28698) and report the following 3-sigma upper limit:
```
T_mid       ||Exposure     ||Filter      ||Limit
T+18 hrs   ||3140s          ||R            ||>20.6
```
The limit is estimated from comparison to nearby USNO B1 stars and is not corrected for Galactic extinction. The VIRT is still in the commissioning phase.
This work is supported by NASA-MUREP-MIRO grant NNX15AP95A, NSF EiR AST Award 1901296, and NSF HBCU-UP AST Award 1831682. This message can be cited.

GCN Circular #28742
M. H. Siegel (PSU) and E. Ambrosi (INAF-IASFPA) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 201020A 144 s after the BAT trigger (Ambrosi et al., GCN Circ. 28696). We confirm the fading source initially reported by Ambrosi et al. and since confirmed by numerous observations (Adachi et al., GCN Circ. 28697; Fu et al., GCN Circ. 28701; Belkin et al., GCN Circ. 28703, Pankow et al. GCN Circ. 28708, Kumar et al. GCN Circ. 28711, Paek et al. GCN Circ. 28713). The afterglow is not detected in UVOT's NUV filters, which would be consistent with the redshift of 2.9 reported by Kann et al. (GCN Circ. 28717).
The preliminary UVOT position is:

   RA  (J2000) =  17:24:54.66 = 261.22773 (deg.)
   Dec (J2000) = +31:25:42.1  =  31.42837 (deg.)

with an estimated uncertainty of 0.44 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)         145          294          147      18.19+/-0.05
white              583          775           38      19.39+/-0.23
white             9805        10713          885      19.71+/-0.09
white           131168       131712          531            >21.48
v                  632          826           38      17.91+/-0.28
v                21653        22150          485      19.26+/-0.28
v                34473        35292          798      19.86+/-0.29
v               125782       126429          629            >19.99
b                  558          750           38            >19.30
b                22822        23469          630      20.35+/-0.21
b                39219        39998          759      21.05+/-0.36
b               130256       131163          885            >20.60
u (fc)             303          552          245      19.76+/-0.27
u                  706          726           19            >18.42
u                29427        29557          128            >19.69
uvw1               681          876           38            >18.16
uvw1             28521        29420          885            >20.42
uvm2               656          676           19            >17.06
uvm2             27614        28514          885            >20.29
uvw2               608          800           38            >18.04
uvw2             10719        34466         1329            >20.71

The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.04 in the direction of the burst (Schlegel et al. 1998).

GCN Circular #28744
A. Ridnaia, S. Golenetskii, R. Aptekar, D. Frederiks, M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline on behalf of the Konus-Wind team, report:
The long-duration GRB 201020A (Swift-BAT trigger #1000926: Ambrosi et al., GCN 28696; Sakamoto et al., GCN 28705; T0(BAT)=05:47:26.16 UT; Fermi-GBM observation: Bissaldi et al., GCN 28706) was detected by Konus-Wind (KW) in the waiting mode.
The burst light curve shows a single emission episode with a duration of ~ 15 s.
The K-W light curve of this burst is available at http://www.ioffe.rssi.ru/LEA/GRBs/GRB201020A/
As observed by Konus-Wind, the burst had a fluence of 1.38(-0.23,0.45)x10^-6 erg/cm2 and a 2.944-s peak flux, measured from ~T0(BAT)+16.5 s, of 1.34(-0.28,+0.47)x10^-7 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
The K-W 3-channel time-integrated spectrum (from ~T0(BAT)+10.6 s to ~T0(BAT)+25.3 s) is best described by simple power-law model with photon index of -2.41(-0.12,+0.17), chi2=0.06/1 dof.
Assuming the redshift z=2.903 (Kann et al., GCN 28717) and a standard cosmology model with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315, and Omega_Lambda = 0.685 (Planck Collaboration, 2014), we estimate the following rest-frame parameters: the isotropic energy release E_iso is ~2.6x10^52 erg, and the peak luminosity L_iso is ~1.0x10^52 erg/s.
All the quoted errors are estimated at the 1 sigma confidence level. All the presented results are preliminary.
GCN Circular #28747
H. Kumar (IITB), J. Stanzin (IAO), V. Bhalerao(IITB), G. C. Anupama (IIA), S. Barway (IIA), report on behalf of the GROWTH-India collaboration:
We observed GRB 201020A reported by Swift-BAT (E. Ambrosi et al., GCN #28696) with 0.7m GROWTH-India telescope. The field was observed in the SDSS r’ filter with multiple 300-sec exposures. We obtained the following late time upper limit:
```
----------------------------------------------------------------------

 JD (mean)| T-T0(hrs) | Filter | Exposure (sec) | Lim_mag (5-sigma) |

----------------------------------------------------------------------

2459144.094375 | 32.47 | r’ | 14 * 300 (stacked) | > 21.47 |

----------------------------------------------------------------------
```
This upper limit is consistent with our best-fit power-law decay from H. Kumar et al., GCN #28711. Magnitudes are in the AB system and calibrated against PanSTARRs PS1 data release, (Flewelling et al., 2018).
The GROWTH India Telescope (GIT) is a 70-cm telescope with a 0.7-degree field of view, set up by the Indian Institute of Astrophysics and the Indian Institute of Technology Bombay with support from the Indo-US Science and Technology Forum (IUSSTF) and the Science and Engineering Research Board (SERB) of the Department of Science and Technology (DST), Government of India (https://sites.google.com/view/growthindia/). It is located at the Indian Astronomical Observatory (Hanle), operated by the Indian Institute of Astrophysics (IIA).
GCN Circular #28789
Amit Kumar (ARIES), Rahul Gupta (ARIES), Ankur Ghosh (ARIES), Dimple (ARIES), Kaushal Sharma (ARIES), Amar Aryan (ARIES), Shashi B. Pandey (ARIES), and Kuntal Misra (ARIES) report:
We observed the field of GRB 201020A (E. Ambrosi et al., GCN 28696) with the 1.3m Devasthal Fast Optical Telescope (DFOT) at Devasthal observatory of Aryabhatta Research Institute of observational sciencES (ARIES), India.
Multiple frames of the GRB field were obtained in the Bessel R and I-bands (15*120sec in each filter). Preliminary photometry on stacked images were performed and calibrated against nearby USNO-B1 stars. We do not detect any OT candidate (see Adachi et al. GCN 28697; Lipunov et al. GCN 28700; Fu et al. GCN 28701; Belkin et al. 28703; Pankov et al. GCN 28708; Kumar et al. GCN 28711; Paek et al. 28713; Kann et al. 28717; Gokuldass et al. 28737; Siegel et al. 28742 and Kumar et al. GCN 28747) within the enhanced XRT position (Osborne et al., GCN 28698).
The 3-sigma upper limits at the location of the afterglow are as follows:
```
DATE       Start UT   Filter  Exposure(sec)    Lim_mag (3-sigma)
2020-10-24 12:51:08    I        15*120            >22.1
2020-10-24 13:23:45    R        15*120            >22.5
```
The estimated magnitudes have not been corrected for the Galactic extinction in the direction of the GRB. This massage may be cited.

Back to JG's homepage

Jochen Greiner, last update: 27-Oct-2020 [Disclaimer]