Gamma-ray Burst 201021C

(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 21 Oct 20 20:30:50 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1001130,   Seg_Num: 0
GRB_RA:           12.550d {+00h 50m 12s} (J2000),
                  12.779d {+00h 51m 07s} (current),
                  11.997d {+00h 47m 59s} (1950)
GRB_DEC:         -55.839d {-55d 50' 20"} (J2000),
                 -55.726d {-55d 43' 33"} (current),
                 -56.111d {-56d 06' 39"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       9110 [cnts]    Image_Peak=414 [image_cnts]
TRIGGER_DUR:     4.096 [sec] 
TRIGGER_INDEX:   298     E_range: 25-100 keV
BKG_INTEN:       73726 [cnts]
BKG_TIME:        73582.15 SOD {20:26:22.15} UT
BKG_DUR:         40 [sec]
GRB_DATE:        19143 TJD;   295 DOY;   20/10/21
GRB_TIME:        73638.66 SOD {20:27:18.66} UT
GRB_PHI:          13.05 [deg]
GRB_THETA:        29.09 [deg]
SOLN_STATUS:     0x20000003
RATE_SIGNIF:     12.28 [sigma]
IMAGE_SIGNIF:    11.84 [sigma]
MERIT_PARAMS:     +1  +0  +0  +2  +2  +1  +0  +0 +37  +0 
SUN_POSTN:       206.87d {+13h 47m 28s}  -11.08d {-11d 05' 02"}
SUN_DIST:        112.16 [deg]   Sun_angle= -11.1 [hr] (East of Sun)
MOON_POSTN:      278.68d {+18h 34m 44s}  -24.54d {-24d 32' 32"}
MOON_DIST:        72.14 [deg]
MOON_ILLUM:      32 [%]
GAL_COORDS:      303.29,-61.29 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      338.38,-53.87 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Coordinates.  
COMMENTS:        This Notice was delayed by more than 60 sec past the end of the trigger integration interval;  
COMMENTS:        probably due to it occurring during a Malindi downlink session.  
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 = 18.02,15.21 [deg].  
COMMENTS:           
COMMENTS:        NOTE: This BAT event is temporally(3.0<100sec) coincident with the FERMI_GBM event (trignum=625004846).

red DSS finding chart ps-file
GCN NOTICE
TITLE: GCN/FERMI NOTICE NOTICE_DATE: Wed 21 Oct 20 20:27:46 UT NOTICE_TYPE: Fermi-GBM Flight Position RECORD_NUM: 47 TRIGGER_NUM: 625004846 GRB_RA: 47.050d {+03h 08m 12s} (J2000), 47.280d {+03h 09m 07s} (current), 46.499d {+03h 06m 00s} (1950) GRB_DEC: -23.600d {-23d 36' 00"} (J2000), -23.521d {-23d 31' 15"} (current), -23.791d {-23d 47' 25"} (1950) GRB_ERROR: 29.35 [deg radius, statistical plus systematic] GRB_INTEN: 61 [cnts/sec] DATA_SIGNIF: 5.30 [sigma] INTEG_TIME: 4.096 [sec] GRB_DATE: 19143 TJD; 295 DOY; 20/10/21 GRB_TIME: 73641.92 SOD {20:27:21.92} UT GRB_PHI: 183.00 [deg] GRB_THETA: 70.00 [deg] DATA_TIME_SCALE: 4.0960 [sec] HARD_RATIO: 0.67 LOC_ALGORITHM: 3 (version number of) MOST_LIKELY: 95% GRB 2nd_MOST_LIKELY: 3% Generic Transient DETECTORS: 0,0,0, 0,0,0, 0,1,0, 0,0,1, 0,0, SUN_POSTN: 206.87d {+13h 47m 28s} -11.08d {-11d 05' 00"} SUN_DIST: 140.05 [deg] Sun_angle= 10.6 [hr] (West of Sun) MOON_POSTN: 278.65d {+18h 34m 36s} -24.54d {-24d 32' 30"} MOON_DIST: 110.79 [deg] MOON_ILLUM: 32 [%] GAL_COORDS: 214.12,-59.00 [deg] galactic lon,lat of the burst (or transient) ECL_COORDS: 36.15,-39.35 [deg] ecliptic lon,lat of the burst (or transient) LC_URL: http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn201021852/quicklook/glg_lc_medres34_bn201021852.gif COMMENTS: Fermi-GBM Flight-calculated Coordinates. COMMENTS: This trigger occurred at longitude,latitude = 189.85,-12.60 [deg]. COMMENTS: The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

 
TITLE:           GCN/SWIFT NOTICE 
NOTICE_DATE:     Wed 21 Oct 20 20:31:19 UT 
NOTICE_TYPE:     Swift-XRT Nack-Position 
TRIGGER_NUM:     1001130,   Seg_Num: 0 
POINT_RA:         12.563d {+00h 50m 15s} (J2000) 
POINT_DEC:       -55.853d {-55d 51' 11"} (J2000) 
IMG_START_DATE:  19143 TJD;   295 DOY;   20/10/21 
IMG_START_TIME:  73740.63 SOD {20:29:00.63} UT,   102.0 [sec] since BAT Trigger Time 
COUNTS:          18    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 21 Oct 20 20:32:19 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1001130,   Seg_Num: 0
GRB_RA:           12.550d {+00h 50m 12s} (J2000),
                  12.779d {+00h 51m 07s} (current),
                  11.997d {+00h 47m 59s} (1950)
GRB_DEC:         -55.839d {-55d 50' 20"} (J2000),
                 -55.726d {-55d 43' 33"} (current),
                 -56.111d {-56d 06' 39"} (1950)
GRB_DATE:        19143 TJD;   295 DOY;   20/10/21
GRB_TIME:        73638.66 SOD {20:27:18.66} UT
TRIGGER_INDEX:   298
GRB_PHI:          13.05 [deg]
GRB_THETA:        29.09 [deg]
DELTA_TIME:      -50.00 [sec]
TRIGGER_DUR:     4.096 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     12.28 [sigma]
IMAGE_SIGNIF:    11.84 [sigma]
LC_URL:          sw01001130000msb.lc
SUN_POSTN:       206.87d {+13h 47m 28s}  -11.08d {-11d 05' 03"}
SUN_DIST:        112.16 [deg]   Sun_angle= -11.1 [hr] (East of Sun)
MOON_POSTN:      278.70d {+18h 34m 48s}  -24.54d {-24d 32' 34"}
MOON_DIST:        72.13 [deg]
MOON_ILLUM:      32 [%]
GAL_COORDS:      303.29,-61.29 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      338.38,-53.87 [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 = 18.02,15.21 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 21 Oct 20 20:35:09 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1001130,   Seg_Num: 0
POINT_RA:         12.563d {+00h 50m 15s} (J2000)
POINT_DEC:       -55.853d {-55d 51' 10"} (J2000)
ROLL:            195.190d
IMG_START_DATE:  19143 TJD;   295 DOY;   20/10/21
IMG_START_TIME:  73743.99 SOD {20:29:03.99} UT,   105.3 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     625004969
X_OFFSET:        767 [pixels]
Y_OFFSET:        1003 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       927
Y_GRB_POS:       1163
BINNING_INDEX:   1
IM_URL:          sw01001130000msuni0131.fits
SUN_POSTN:       206.87d {+13h 47m 29s}  -11.09d {-11d 05' 06"}
SUN_DIST:        112.14 [deg]   Sun_angle= -11.1 [hr] (East of Sun)
MOON_POSTN:      278.73d {+18h 34m 55s}  -24.54d {-24d 32' 36"}
MOON_DIST:        72.12 [deg]
MOON_ILLUM:      32 [%]
GAL_COORDS:      303.28,-61.27 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      338.38,-53.89 [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 21 Oct 20 20:42:08 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1001130,   Seg_Num: 0
POINT_RA:         12.568d {+00h 50m 16s} (J2000)
POINT_DEC:       -55.854d {-55d 51' 14"} (J2000)
POINT_ROLL:      195.187d
IMG_START_DATE:  19143 TJD;   295 DOY;   20/10/21
IMG_START_TIME:  73956.12 SOD {20:32:36.12} UT,   317.5 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.404
N_STARS:         41
X_OFFSET:        208 [pixels]
Y_OFFSET:        444 [pixels]
X_MAX:           1647 [pixels]
Y_MAX:           1883 [pixels]
DET_THRESH:      6
PHOTO_THRESH:    2
SL_URL:          sw01001130000msufc0317.fits
SUN_POSTN:       206.88d {+13h 47m 30s}  -11.09d {-11d 05' 12"}
SUN_DIST:        112.14 [deg]   Sun_angle= -11.1 [hr] (East of Sun)
MOON_POSTN:      278.80d {+18h 35m 13s}  -24.55d {-24d 32' 43"}
MOON_DIST:        72.08 [deg]
MOON_ILLUM:      32 [%]
GAL_COORDS:      303.27,-61.27 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      338.38,-53.89 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 21 Oct 20 20:43:19 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1001130,   Seg_Num: 0
POINT_RA:         12.568d {+00h 50m 16s} (J2000)
POINT_DEC:       -55.854d {-55d 51' 14"} (J2000)
ROLL:            195.187d
IMG_START_DATE:  19143 TJD;   295 DOY;   20/10/21
IMG_START_TIME:  73956.12 SOD {20:32:36.12} UT,   317.5 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     625005181
X_OFFSET:        767 [pixels]
Y_OFFSET:        1003 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       927
Y_GRB_POS:       1163
BINNING_INDEX:   1
IM_URL:          sw01001130000msuni0343.fits
SUN_POSTN:       206.88d {+13h 47m 30s}  -11.09d {-11d 05' 13"}
SUN_DIST:        112.14 [deg]   Sun_angle= -11.1 [hr] (East of Sun)
MOON_POSTN:      278.82d {+18h 35m 16s}  -24.55d {-24d 32' 44"}
MOON_DIST:        72.07 [deg]
MOON_ILLUM:      32 [%]
GAL_COORDS:      303.27,-61.27 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      338.38,-53.89 [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 21 Oct 20 20:42:25 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1001130,   Seg_Num: 0
POINT_RA:         12.568d {+00h 50m 16s} (J2000)
POINT_DEC:       -55.854d {-55d 51' 14"} (J2000)
POINT_ROLL:      195.187d
IMG_START_DATE:  19143 TJD;   295 DOY;   20/10/21
IMG_START_TIME:  73956.12 SOD {20:32:36.12} UT,   317.5 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.404
N_STARS:         41
X_OFFSET:        208 [pixels]
Y_OFFSET:        444 [pixels]
X_MAX:           1647 [pixels]
Y_MAX:           1883 [pixels]
DET_THRESH:      6
PHOTO_THRESH:    2
SL_URL:          sw01001130000msufc0317.fits
SUN_POSTN:       206.88d {+13h 47m 30s}  -11.09d {-11d 05' 12"}
SUN_DIST:        112.14 [deg]   Sun_angle= -11.1 [hr] (East of Sun)
MOON_POSTN:      278.81d {+18h 35m 13s}  -24.55d {-24d 32' 43"}
MOON_DIST:        72.08 [deg]
MOON_ILLUM:      32 [%]
GAL_COORDS:      303.27,-61.27 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      338.38,-53.89 [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 21 Oct 20 20:47:50 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1001130,   Seg_Num: 0
POINT_RA:         12.568d {+00h 50m 16s} (J2000)
POINT_DEC:       -55.855d {-55d 51' 15"} (J2000)
POINT_ROLL:      195.187d
IMG_START_DATE:  19143 TJD;   295 DOY;   20/10/21
IMG_START_TIME:  74512.37 SOD {20:41:52.37} UT,   873.7 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        0.409
N_STARS:         43
X_OFFSET:        208 [pixels]
Y_OFFSET:        444 [pixels]
X_MAX:           1647 [pixels]
Y_MAX:           1883 [pixels]
DET_THRESH:      6
PHOTO_THRESH:    2
SL_URL:          sw01001130000msufc0873.fits
SUN_POSTN:       206.88d {+13h 47m 31s}  -11.09d {-11d 05' 17"}
SUN_DIST:        112.14 [deg]   Sun_angle= -11.1 [hr] (East of Sun)
MOON_POSTN:      278.86d {+18h 35m 27s}  -24.55d {-24d 32' 48"}
MOON_DIST:        72.05 [deg]
MOON_ILLUM:      32 [%]
GAL_COORDS:      303.27,-61.27 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      338.38,-53.89 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 21 Oct 20 20:35:27 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1001130,   Seg_Num: 0
POINT_RA:         12.563d {+00h 50m 15s} (J2000)
POINT_DEC:       -55.853d {-55d 51' 10"} (J2000)
ROLL:            195.190d
IMG_START_DATE:  19143 TJD;   295 DOY;   20/10/21
IMG_START_TIME:  73743.99 SOD {20:29:03.99} UT,   105.3 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     625004969
X_OFFSET:        767 [pixels]
Y_OFFSET:        1003 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       927
Y_GRB_POS:       1163
BINNING_INDEX:   1
IM_URL:          sw01001130000msuni0131.fits
SUN_POSTN:       206.87d {+13h 47m 29s}  -11.09d {-11d 05' 06"}
SUN_DIST:        112.14 [deg]   Sun_angle= -11.1 [hr] (East of Sun)
MOON_POSTN:      278.73d {+18h 34m 56s}  -24.54d {-24d 32' 37"}
MOON_DIST:        72.12 [deg]
MOON_ILLUM:      32 [%]
GAL_COORDS:      303.28,-61.27 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      338.38,-53.89 [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 21 Oct 20 20:36:28 UT
NOTICE_TYPE:     Swift-UVOT Position
TRIGGER_NUM:     1001130,   Seg_Num: 0
GRB_RA:           12.5285d {+00h 50m 06.83s} (J2000),
                  12.7578d {+00h 51m 01.86s} (current),
                  11.9756d {+00h 47m 54.13s} (1950)
GRB_DEC:         -55.8657d {-55d 51' 56.5"} (J2000),
                 -55.7527d {-55d 45' 09.6"} (current),
                 -56.1378d {-56d 08' 15.9"} (1950)
GRB_ERROR:       1.1 [arcsec radius, statistical only]
GRB_MAG:         17.19 +/- 0.40 [mag]
FILTER:          10, White
IMG_START_DATE:  19143 TJD;   295 DOY;   20/10/21
IMG_START_TIME:  73740.00 SOD {20:29:00.00} UT,   101.3 [sec] since BAT Trigger Time
SUN_POSTN:       206.87d {+13h 47m 29s}  -11.09d {-11d 05' 07"}
SUN_DIST:        112.13 [deg]   Sun_angle= -11.1 [hr] (East of Sun)
MOON_POSTN:      278.74d {+18h 34m 58s}  -24.54d {-24d 32' 38"}
MOON_DIST:        72.09 [deg]
MOON_ILLUM:      32 [%]
GAL_COORDS:      303.32,-61.26 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      338.34,-53.89 [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 NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 21 Oct 20 20:33:07 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1001130,   Seg_Num: 0
POINT_RA:         12.563d {+00h 50m 15s} (J2000)
POINT_DEC:       -55.853d {-55d 51' 10"} (J2000)
POINT_ROLL:      195.190d
IMG_START_DATE:  19143 TJD;   295 DOY;   20/10/21
IMG_START_TIME:  73743.99 SOD {20:29:03.99} UT,   105.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.482
N_STARS:         28
X_OFFSET:        448 [pixels]
Y_OFFSET:        684 [pixels]
X_MAX:           1407 [pixels]
Y_MAX:           1643 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw01001130000msufc0105.fits
SUN_POSTN:       206.87d {+13h 47m 29s}  -11.08d {-11d 05' 04"}
SUN_DIST:        112.15 [deg]   Sun_angle= -11.1 [hr] (East of Sun)
MOON_POSTN:      278.71d {+18h 34m 50s}  -24.54d {-24d 32' 35"}
MOON_DIST:        72.13 [deg]
MOON_ILLUM:      32 [%]
GAL_COORDS:      303.28,-61.27 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      338.38,-53.89 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 21 Oct 20 20:34:49 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     1001130,   Seg_Num: 0
GRB_RA:           12.5274d {+00h 50m 06.57s} (J2000),
                  12.7567d {+00h 51m 01.60s} (current),
                  11.9745d {+00h 47m 53.87s} (1950)
GRB_DEC:         -55.8662d {-55d 51' 58.3"} (J2000),
                 -55.7532d {-55d 45' 11.4"} (current),
                 -56.1383d {-56d 08' 17.7"} (1950)
GRB_ERROR:       3.5 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  19143 TJD;   295 DOY;   20/10/21
IMG_START_TIME:  73808.00 SOD {20:30:08.00} UT,   169.3 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       206.87d {+13h 47m 29s}  -11.09d {-11d 05' 05"}
SUN_DIST:        112.13 [deg]   Sun_angle= -11.1 [hr] (East of Sun)
MOON_POSTN:      278.73d {+18h 34m 54s}  -24.54d {-24d 32' 36"}
MOON_DIST:        72.10 [deg]
MOON_ILLUM:      32 [%]
GAL_COORDS:      303.32,-61.26 [deg] galactic lon,lat of the burst
ECL_COORDS:      338.34,-53.89 [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 0.11% < P(seren) < 0.58%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 21 Oct 20 20:42:40 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     1001130,   Seg_Num: 0
GRB_RA:           12.5298d {+00h 50m 07.15s} (J2000),
                  12.7591d {+00h 51m 02.17s} (current),
                  11.9769d {+00h 47m 54.45s} (1950)
GRB_DEC:         -55.8663d {-55d 51' 58.6"} (J2000),
                 -55.7533d {-55d 45' 11.7"} (current),
                 -56.1384d {-56d 08' 18.1"} (1950)
GRB_ERROR:       2.3 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  19143 TJD;   295 DOY;   20/10/21
IMG_START_TIME:  73808.00 SOD {20:30:08.00} UT,   169.3 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       206.88d {+13h 47m 30s}  -11.09d {-11d 05' 12"}
SUN_DIST:        112.12 [deg]   Sun_angle= -11.1 [hr] (East of Sun)
MOON_POSTN:      278.81d {+18h 35m 14s}  -24.55d {-24d 32' 43"}
MOON_DIST:        72.05 [deg]
MOON_ILLUM:      32 [%]
GAL_COORDS:      303.32,-61.26 [deg] galactic lon,lat of the burst
ECL_COORDS:      338.34,-53.89 [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 0.11% < P(seren) < 0.58%.

GCN Circular #28730
A. Y. Lien (GSFC/UMBC), M. G. Bernardini (INAF-OAB), D. N. Burrows (PSU), P. D'Avanzo (INAF-OAB), J.D. Gropp (PSU), J. A. Kennea (PSU), N. J. Klingler (PSU), H. A. Krimm (NSF), S. Laha (GSFC/UMBC/CRESST), F. E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), M. J. Moss (GWU), T. Sakamoto (AGU), T. Sbarrato (INAF-OAB) and B. Sbarufatti (PSU) report on behalf of the Neil Gehrels Swift Observatory Team:
At 20:27:18 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 201021C (trigger=1001130). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 12.550, -55.839 which is
```
   RA(J2000) = 00h 50m 12s
   Dec(J2000) = -55d 50' 20"
```
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 25 sec. The peak count rate was ~1200 counts/sec (15-350 keV), at ~2 sec after the trigger.
The XRT began observing the field at 20:29:00.6 UT, 102.0 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source located at RA, Dec 12.53057, -55.86729 which is equivalent to:
```
   RA(J2000)  = 00h 50m 07.34s
   Dec(J2000) = -55d 52' 02.2"
```
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This location is 109 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 2.05 x 10^20 cm^-2 (Willingale et al. 2013).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 105 seconds after the BAT trigger. There is a candidate afterglow in the list of sources generated on-board at
```
  RA(J2000)  =	00:50:06.85 =  12.52855
  DEC(J2000) = -55:51:56.7  = -55.86576
```
with a 90%-confidence error radius of about 1.10 arc sec. This position is 2.8 arc sec. from the center of the XRT error circle. The estimated magnitude is 17.19. No correction has been made for the expected extinction corresponding to E(B-V) of 0.02.
Burst Advocate for this burst is A. Y. Lien (amy.y.lien AT nasa.gov). 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 Circular #28731
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-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB201021.85 (trigger No 1001130,00h 50m 12.00s , -55d 50m 20.4s, R=0.05) errorbox 73 sec after notice time and 295 sec after trigger time at 2020-10-21 20:32:14 UT, with upper limit up to 17.8 mag. The observations began at zenith distance = 26 deg. The sun altitude is -39.5 deg.
The galactic latitude b = -62 deg., longitude l = 303 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1466597
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

     325 |         MASTER-SAAO |  P/ |    60 | 17.7 |        
     325 |         MASTER-SAAO | P\  |    60 | 17.8 |        
```
The observation and reduction will continue. The message may be cited.
GCN Circular #28733
V. Lipunov, V.Kornilov, E.Gorbovskoy, N.Tiurina, P.Balanutsa, A.Kuznetsov,K.Zhirkov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, A.Chasovnikov, A.Pozdnyakov, V.Topolev, D.Cheryasov(Lomonosov Moscow State University, SAI, Physics Department), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico FelixAguilar OAFA), R. Rebolo, M. Serra(The Instituto de Astrofisica de Canarias), D. Buckley (South African Astronomical Observatory), O.A. Gres, N.M. Budnev (Irkutsk State University, API), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov, Yu. Sergienko (Blagoveschensk Educational State University)
MASTER-SAAO started GRB 201021C (Lien et al. GCN 28730) observation by MASTER-II (2x4sq.deg.) in 2020-10-21 20:31:04UT and also detected OT at Swift-UVOT position (Lien et al. GCN 28730) in 2 polarization filters. MASTER very wide field cameras (Lipunov et al. 2010, Advances in Astronomy, vol.2010, 30L) observed this GRB _synchronously_ . Observation and reduction will continue.
GCN Circular #28736
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team.
Using 742 s of XRT Photon Counting mode data and 2 UVOT images for GRB 201021C, 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 = 12.52888, -55.86549 which is equivalent to:
```
RA (J2000): 00h 50m 6.93s
Dec (J2000): -55d 51' 55.8"
```
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 #28739
J.-B. Vielfaure (GEPI - Paris Observatory), D. Xu (NAO/CAS), J. Palmerio (GEPI - Paris Observatory), P. D'Avanzo (INAF-OAB), D. B. Malesani (DTU Space), J. P. U. Fynbo (DAWN/NBI), V. D'Elia (ASI/SSDC), D. A. Kann (HETH/IAA-CSIC) and N. R. Tanvir (Univ. Leicester) report on behalf of the Stargate collaboration:
We observed the optical afterglow of GRB 201021C (Lien et al., GCN 28730; Lipunov et al., GCN 28733) using the ESO VLT UT3 (Melipal) equipped with the X-shooter spectrograph. Our spectra cover the wavelength range 3000-21000 AA, and consist of 4 exposures by 600 s each. The observation started at 03:29:00 UT on 2020 Oct 22 (7.02 hr after the GRB).
In a 30 s image taken with the acquisition camera on Oct 22.14 UT, we detect the optical afterglow, for which we measure a magnitude r = 19.97 +/- 0.02 (AB, calibrated against nearby stars from the SkyMapper catalog; Wolf et al. 2018, PASA, 35, 010).
We clearly detect continuum over the whole X-shooter spectrum. From detection of multiple absorption features, which we interpret as due to Si II, Al II, Al III, Fe II and Mg II, we infer a redshift z = 1.070. In particular, weak fine structure lines from Fe II* are visible, which confirm the association of the absorption system with the GRB. We also detect Mg II and Mg I absorption features from an intervening system at z = 0.805.
We acknowledge excellent support from the ESO observing staff in Paranal, in particular Bin Yang and Fernando Selman.
GCN Circular #28745
S. R. Oates (U.Birmingham) and A. Y. Lien (GSFC/UMBC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 201021C 105 s after the BAT trigger (Lien et al., GCN Circ. 28730). A source consistent with the XRT position (Beardmore et al. GCN Circ. 28736) is detected in the initial UVOT exposures.
The preliminary UVOT position is:
```
 RA  (J2000) =  00:50:06.93 =  12.52886 (deg.)
 Dec (J2000) = -55:51:56.8  = -55.86577 (deg.)
```
with an estimated uncertainty of 0.42 arc sec. (radius, 90% confidence).
Preliminary detections using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)           Mag
white (FC)      105          255         147         16.66 +/- 0.03
white              598          617           19         16.22 +/- 0.05
v                    647          667           19         16.49 +/- 0.16
b                    573          593           20         16.80 +/- 0.10 
u  (FC)           317          567         246         15.76 +/- 0.03 
u                    722          742           19         16.06 +/- 0.10
uvm2             672          692           19         16.43 +/- 0.24       
uvw2             623          643           19         16.68 +/- 0.22
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.02 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #28748
S. Lesage (UAH) and C. Meegan (UAH) report on behalf of the Fermi GBM Team:
"At 20:27:21.92 UT on 21 October 2020, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 201021C (trigger 625004846 / 201021852) which was also detected by the Swift/BAT (A. Y. Lien et al. 2020, GCN 28730). The Fermi GBM on-ground localization is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is ~59 degrees.
The GBM light curve shows a single bright peak with a duration (T90) of about 35.3 s (50-300 keV). The time-averaged spectrum from T0-5.9 s to T0+29.4 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.1 +/- 0.2 and the cutoff energy, parameterized as Epeak, is 131.1 +/- 28.2 keV.
The event fluence (10-1000 keV) in this time interval is (1.7 +/- 0.2)E-06 erg/cm^2. The 1.024-sec peak photon flux measured starting from T0-1.9 s in the 10-1000 keV band is 1.82 +/- 0.2 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 #28754
D.N. Burrows (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , J. D. Gropp (PSU), J.A. Kennea (PSU) and A.Y. Lien report on behalf of the Swift-XRT team:
We have analysed 4.3 ks of XRT data for GRB 201021C (Lien et al. GCN Circ. 28730), from 105 s to 58.8 ks after the BAT trigger. The data comprise 62 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN Circ. 28736).
The light curve can be modelled with a power-law decay with a decay index of alpha=1.22 (+0.07, -0.06).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.62 (+0.19, -0.16). The best-fitting absorption column is 5 (+21, -5) x 10^20 cm^-2, at a redshift of 1.07, in addition to the Galactic value of 2.0 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 4.0 x 10^-11 (4.2 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Galactic foreground: 2.0 x 10^20 cm^-2
Intrinsic column:    5 (+21, -5) x 10^20 cm^-2 at z=1.07
Photon index:	     1.62 (+0.19, -0.16)
```
If the light curve continues to decay with a power-law decay index of 1.22, the count rate at T+24 hours will be 2.7 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.1 x 10^-13 (1.1 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/01001130.
This circular is an official product of the Swift-XRT team.
GCN Circular #28755
M. Stamatikos (OSU), 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), T. Sakamoto (AGU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-240 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 201021C (trigger #1001130) (Lien, et al., GCN Circ. 28730). The BAT ground-calculated position is RA, Dec = 12.503, -55.862 deg which is
```
   RA(J2000)  =  00h 50m 00.6s 
   Dec(J2000) = -55d 51' 44.0" 
```
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment). The partial coding was 80%.
The mask-weighted light curve shows a single peak running from ~T-5 sec to T+20 sec, with a broad peak around T+3 sec. T90 (15-350 keV) is 24.38 +- 6.76 sec (estimated error including systematics).
The time-averaged spectrum from T-4.19 to T+27.95 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.63 +- 0.15. The fluence in the 15-150 keV band is 1.0 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T-3.62 sec in the 15-150 keV band is 1.0 +- 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/1001130/BA/
GCN Circular #31752
A. Klotz (CNRS-OMP-IRAP), M. Fortune, R. Augerai (Universite de la Renuion), P. Thierry� (AGORA), L. Eymar, S. Antier, M. Boer, A. de Ugarte Postigo (CNRS-OCA-ARTEMIS),
We analyzed archive images of the SWIFT trigger 1001130 (GRB 201021C, BAT detection by� Lien et al. GCN Circ. 28730, early optical ground observations by Lipunov et al. GCN Circ. 28733, redshift by Vielfaure et al. GCN Circ. 28739) with the TAROT robotic telescope (D=18cm) located at Les Makes Observatory, Reunion Island, France.
Images were acquired without any filter, camera FLI PL16803 and Takahashi Epsilon 180ED.
According the reference star NOMAD-1 0340-0006028 R=13.85 we give the photometry of the GRB optical transient:
```
 �t1(s) t2(s)���� R� dmag
 �� 813�� 993 15.92� 0.04
 � 1003� 1183 16.02� 0.03
 � 1190� 1370 16.24� 0.05
 � 1388� 1568 16.28� 0.04
 � 1575� 1755 16.52� 0.06
 � 1762� 1942 16.62� 0.06
 � 2048� 2228 16.80� 0.08
 � 2236� 2416 16.92� 0.09
 � 2425� 3178 17.12� 0.06
 � 3198� 4132 17.54� 0.09
 � 4139� 9462 17.82� 0.10
```
t1 and t2 are start and stop acquisition since the trigger.
Magnitudes are not corrected for Galactic dust extinction.

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Jochen Greiner, last update: 13-Mar-2022 [Disclaimer]