Gamma-ray Burst 201024A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 24 Oct 20 02:49:11 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1001514,   Seg_Num: 0
GRB_RA:          125.948d {+08h 23m 47s} (J2000),
                 126.220d {+08h 24m 53s} (current),
                 125.293d {+08h 21m 10s} (1950)
GRB_DEC:          +3.377d {+03d 22' 38"} (J2000),
                  +3.309d {+03d 18' 32"} (current),
                  +3.539d {+03d 32' 21"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       1687 [cnts]    Image_Peak=105 [image_cnts]
TRIGGER_DUR:     0.512 [sec] 
TRIGGER_INDEX:   69     E_range: 15-50 keV
BKG_INTEN:       19521 [cnts]
BKG_TIME:        10126.14 SOD {02:48:46.14} UT
BKG_DUR:         8 [sec]
GRB_DATE:        19146 TJD;   298 DOY;   20/10/24
GRB_TIME:        10139.13 SOD {02:48:59.13} UT
GRB_PHI:         -99.77 [deg]
GRB_THETA:        35.57 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     15.62 [sigma]
IMAGE_SIGNIF:    9.01 [sigma]
MERIT_PARAMS:     +1  +0  +0  -1  +1  -1  +0  +0 -10  +0 
SUN_POSTN:       209.02d {+13h 56m 05s}  -11.88d {-11d 52' 31"}
SUN_DIST:         83.65 [deg]   Sun_angle= 5.5 [hr] (West of Sun)
MOON_POSTN:      311.38d {+20h 45m 30s}  -21.86d {-21d 51' 30"}
MOON_DIST:       160.79 [deg]
MOON_ILLUM:      56 [%]
GAL_COORDS:      220.75, 22.04 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      127.46,-15.51 [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 = 358.64,-16.03 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 24 Oct 20 02:50:52 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     1001514,   Seg_Num: 0
GRB_RA:          125.9507d {+08h 23m 48.1s} (J2000),
                 126.2228d {+08h 24m 53.4s} (current),
                 125.2966d {+08h 21m 11.1s} (1950)
GRB_DEC:          +3.3549d {+03d 21' 17.6"} (J2000),
                  +3.2867d {+03d 17' 11.9"} (current),
                  +3.5171d {+03d 31' 01.4"} (1950)
GRB_ERROR:       5.8 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       31 [cnts]
IMG_START_DATE:  19146 TJD;   298 DOY;   20/10/24
IMG_START_TIME:  10214.02 SOD {02:50:14.02} UT,   74.9 [sec] since BAT Trigger Time
CENTROID_X:      249.50,  raw= 250  [pixels]
CENTROID_Y:      271.93,  raw= 272  [pixels]
ROLL:            102.33 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -61.66
GRB_POS_XRT_Z:   -136.47
IMAGE_URL:       sw01001514000msxps_rw.img
SUN_POSTN:       209.02d {+13h 56m 05s}  -11.88d {-11d 52' 33"}
SUN_DIST:         83.65 [deg]   Sun_angle= 5.5 [hr] (West of Sun)
MOON_POSTN:      311.39d {+20h 45m 34s}  -21.86d {-21d 51' 19"}
MOON_DIST:       160.76 [deg]
MOON_ILLUM:      56 [%]
GAL_COORDS:      220.77, 22.03 [deg] galactic lon,lat of the burst
ECL_COORDS:      127.47,-15.53 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 24 Oct 20 02:50:42 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     1001514,   Seg_Num: 0
GRB_RA:          125.9507d {+08h 23m 48.16s} (J2000),
                 126.2228d {+08h 24m 53.47s} (current),
                 125.2966d {+08h 21m 11.18s} (1950)
GRB_DEC:          +3.3549d {+03d 21' 17.6"} (J2000),
                  +3.2867d {+03d 17' 11.9"} (current),
                  +3.5171d {+03d 31' 01.4"} (1950)
GRB_ERROR:       6.1 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       6.41e-10 [erg/cm2/sec]
GRB_SIGNIF:      5.56 [sigma]
IMG_START_DATE:  19146 TJD;   298 DOY;   20/10/24
IMG_START_TIME:  10214.02 SOD {02:50:14.02} UT,   74.9 [sec] since BAT Trigger Time
TAM[0-3]:        327.64 237.17 261.60 243.73
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       209.02d {+13h 56m 05s}  -11.88d {-11d 52' 32"}
SUN_DIST:         83.65 [deg]   Sun_angle= 5.5 [hr] (West of Sun)
MOON_POSTN:      311.39d {+20h 45m 34s}  -21.86d {-21d 51' 20"}
MOON_DIST:       160.76 [deg]
MOON_ILLUM:      56 [%]
GAL_COORDS:      220.77, 22.03 [deg] galactic lon,lat of the burst
ECL_COORDS:      127.47,-15.53 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 1.34 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 21 Oct 20 20:33:25 UT
NOTICE_TYPE:     Swift-UVOT Processed 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 51s}  -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 Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 24 Oct 20 02:53:07 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve 
TRIGGER_NUM:     1001514,   Seg_Num: 0
GRB_RA:          125.948d {+08h 23m 47s} (J2000),
                 126.220d {+08h 24m 53s} (current),
                 125.293d {+08h 21m 10s} (1950)
GRB_DEC:          +3.377d {+03d 22' 38"} (J2000),
                  +3.309d {+03d 18' 32"} (current),
                  +3.539d {+03d 32' 21"} (1950)
GRB_DATE:        19146 TJD;   298 DOY;   20/10/24
GRB_TIME:        10139.13 SOD {02:48:59.13} UT
TRIGGER_INDEX:   69
GRB_PHI:         -99.77 [deg]
GRB_THETA:        35.57 [deg]
DELTA_TIME:      -18.00 [sec]
TRIGGER_DUR:     0.512 [sec]
SOLN_STATUS:     0x3
RATE_SIGNIF:     15.62 [sigma]
IMAGE_SIGNIF:    9.01 [sigma]
LC_URL:          sw01001514000msb.lc
SUN_POSTN:       209.02d {+13h 56m 05s}  -11.88d {-11d 52' 35"}
SUN_DIST:         83.65 [deg]   Sun_angle= 5.5 [hr] (West of Sun)
MOON_POSTN:      311.41d {+20h 45m 39s}  -21.85d {-21d 51' 04"}  
MOON_DIST:       160.78 [deg] 
MOON_ILLUM:      56 [%]
GAL_COORDS:      220.75, 22.04 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      127.46,-15.51 [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 = 358.64,-16.03 [deg].

GCN Circular #28759
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 GRB201024.12 (trigger No 1001514,08h 23m 47.52s , +03d 22m 37.2s, R=0.05) errorbox 28 sec after notice time and 43 sec after trigger time at 2020-10-24 02:49:43 UT, with upper limit up to 16.2 mag. Observations started at twilight. The observations began at zenith distance = 46 deg. The sun altitude is -12.7 deg.
MASTER-IAC robotic telescope located in Spain (IAC Teide Observatory) was pointed to the Swift GRB201024.12 errorbox 146 sec after notice time and 161 sec after trigger time at 2020-10-24 02:51:40 UT, with upper limit up to 16.9 mag. The observations began at zenith distance = 67 deg. The sun altitude is -56.7 deg.
The galactic latitude b = 23 deg., longitude l = 221 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1467863
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

      49 |         MASTER-SAAO |  P/ |    10 | 16.0 |        
      49 |         MASTER-SAAO | P\  |    10 | 16.2 |        
      78 |         MASTER-SAAO |  P/ |    10 | 15.9 |        
      78 |         MASTER-SAAO | P\  |    10 | 16.1 |        
     171 |          MASTER-IAC |   C |    20 | 16.7 |        
     206 |          MASTER-IAC |   C |    20 | 16.5 |        
     242 |          MASTER-IAC |   C |    30 | 16.9 |        
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 24 Oct 20 03:00:07 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1001514,   Seg_Num: 0
POINT_RA:        125.915d {+08h 23m 40s} (J2000)
POINT_DEC:        +3.380d {+03d 22' 48"} (J2000)
POINT_ROLL:      102.330d
IMG_START_DATE:  19146 TJD;   298 DOY;   20/10/24
IMG_START_TIME:  10634.40 SOD {02:57:14.40} UT,   495.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.963
N_STARS:         68
X_OFFSET:        667 [pixels]
Y_OFFSET:        416 [pixels]
X_MAX:           1626 [pixels]
Y_MAX:           1375 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    8
SL_URL:          sw01001514000msufc0495.fits
SUN_POSTN:       209.03d {+13h 56m 06s}  -11.88d {-11d 52' 41"}
SUN_DIST:         83.69 [deg]   Sun_angle= 5.5 [hr] (West of Sun)
MOON_POSTN:      311.48d {+20h 45m 55s}  -21.84d {-21d 50' 19"}
MOON_DIST:       160.77 [deg]
MOON_ILLUM:      56 [%]
GAL_COORDS:      220.73, 22.01 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      127.42,-15.52 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 24 Oct 20 03:00:25 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1001514,   Seg_Num: 0
POINT_RA:        125.915d {+08h 23m 40s} (J2000)
POINT_DEC:        +3.380d {+03d 22' 48"} (J2000)
POINT_ROLL:      102.330d
IMG_START_DATE:  19146 TJD;   298 DOY;   20/10/24
IMG_START_TIME:  10634.40 SOD {02:57:14.40} UT,   495.3 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        2.963
N_STARS:         68
X_OFFSET:        667 [pixels]
Y_OFFSET:        416 [pixels]
X_MAX:           1626 [pixels]
Y_MAX:           1375 [pixels]
DET_THRESH:      14
PHOTO_THRESH:    8
SL_URL:          sw01001514000msufc0495.fits
SUN_POSTN:       209.03d {+13h 56m 07s}  -11.88d {-11d 52' 41"}
SUN_DIST:         83.69 [deg]   Sun_angle= 5.5 [hr] (West of Sun)
MOON_POSTN:      311.48d {+20h 45m 56s}  -21.84d {-21d 50' 18"}
MOON_DIST:       160.77 [deg]
MOON_ILLUM:      56 [%]
GAL_COORDS:      220.73, 22.01 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      127.42,-15.52 [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:     Sat 24 Oct 20 03:00:34 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     1001514,   Seg_Num: 0
GRB_RA:          125.9521d {+08h 23m 48.50s} (J2000),
                 126.2242d {+08h 24m 53.80s} (current),
                 125.2980d {+08h 21m 11.51s} (1950)
GRB_DEC:          +3.3540d {+03d 21' 14.4"} (J2000),
                  +3.2858d {+03d 17' 08.7"} (current),
                  +3.5162d {+03d 30' 58.1"} (1950)
GRB_ERROR:       2.4 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  19146 TJD;   298 DOY;   20/10/24
IMG_START_TIME:  10589.00 SOD {02:56:29.00} UT,   449.9 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       209.03d {+13h 56m 07s}  -11.88d {-11d 52' 41"}
SUN_DIST:         83.65 [deg]   Sun_angle= 5.5 [hr] (West of Sun)
MOON_POSTN:      311.48d {+20h 45m 56s}  -21.84d {-21d 50' 17"}
MOON_DIST:       160.76 [deg]
MOON_ILLUM:      56 [%]
GAL_COORDS:      220.77, 22.03 [deg] galactic lon,lat of the burst
ECL_COORDS:      127.47,-15.53 [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:        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:     Sat 24 Oct 20 03:02:44 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1001514,   Seg_Num: 0
POINT_RA:        125.915d {+08h 23m 40s} (J2000)
POINT_DEC:        +3.380d {+03d 22' 48"} (J2000)
ROLL:            102.330d
IMG_START_DATE:  19146 TJD;   298 DOY;   20/10/24
IMG_START_TIME:  10634.40 SOD {02:57:14.40} UT,   495.3 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     625201060
X_OFFSET:        986 [pixels]
Y_OFFSET:        735 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1146
Y_GRB_POS:       895
BINNING_INDEX:   1
IM_URL:          sw01001514000msuni0521.fits
SUN_POSTN:       209.03d {+13h 56m 07s}  -11.88d {-11d 52' 43"}
SUN_DIST:         83.69 [deg]   Sun_angle= 5.5 [hr] (West of Sun)
MOON_POSTN:      311.50d {+20h 46m 01s}  -21.83d {-21d 50' 03"}
MOON_DIST:       160.77 [deg]
MOON_ILLUM:      56 [%]
GAL_COORDS:      220.73, 22.01 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      127.42,-15.52 [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 24 Oct 20 03:02:51 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1001514,   Seg_Num: 0
POINT_RA:        125.915d {+08h 23m 40s} (J2000)
POINT_DEC:        +3.380d {+03d 22' 48"} (J2000)
ROLL:            102.330d
IMG_START_DATE:  19146 TJD;   298 DOY;   20/10/24
IMG_START_TIME:  10634.40 SOD {02:57:14.40} UT,   495.3 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     625201060
X_OFFSET:        986 [pixels]
Y_OFFSET:        735 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1146
Y_GRB_POS:       895
BINNING_INDEX:   1
IM_URL:          sw01001514000msuni0521.fits
SUN_POSTN:       209.03d {+13h 56m 07s}  -11.88d {-11d 52' 43"}
SUN_DIST:         83.69 [deg]   Sun_angle= 5.5 [hr] (West of Sun)
MOON_POSTN:      311.50d {+20h 46m 01s}  -21.83d {-21d 50' 02"}
MOON_DIST:       160.77 [deg]
MOON_ILLUM:      56 [%]
GAL_COORDS:      220.73, 22.01 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      127.42,-15.52 [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:     Sat 24 Oct 20 03:05:19 UT
NOTICE_TYPE:     Swift-UVOT Position
TRIGGER_NUM:     1001514,   Seg_Num: 0
GRB_RA:          125.9522d {+08h 23m 48.52s} (J2000),
                 126.2243d {+08h 24m 53.83s} (current),
                 125.2981d {+08h 21m 11.54s} (1950)
GRB_DEC:          +3.3540d {+03d 21' 14.4"} (J2000),
                  +3.2858d {+03d 17' 08.7"} (current),
                  +3.5162d {+03d 30' 58.1"} (1950)
GRB_ERROR:       0.6 [arcsec radius, statistical only]
GRB_MAG:         17.85 +/- 0.14 [mag]
FILTER:          10, White
IMG_START_DATE:  19146 TJD;   298 DOY;   20/10/24
IMG_START_TIME:  10631.00 SOD {02:57:11.00} UT,   491.9 [sec] since BAT Trigger Time
SUN_POSTN:       209.03d {+13h 56m 07s}  -11.88d {-11d 52' 45"}
SUN_DIST:         83.65 [deg]   Sun_angle= 5.5 [hr] (West of Sun)
MOON_POSTN:      311.53d {+20h 46m 07s}  -21.83d {-21d 49' 46"}
MOON_DIST:       160.75 [deg]
MOON_ILLUM:      56 [%]
GAL_COORDS:      220.77, 22.03 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      127.47,-15.53 [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 6.5 arcsec from the XRT position.  
COMMENTS:        Result based on Genie data.  
COMMENTS:        Notice generated automatically.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 24 Oct 20 03:07:08 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1001514,   Seg_Num: 0
POINT_RA:        125.915d {+08h 23m 40s} (J2000)
POINT_DEC:        +3.380d {+03d 22' 48"} (J2000)
POINT_ROLL:      102.329d
IMG_START_DATE:  19146 TJD;   298 DOY;   20/10/24
IMG_START_TIME:  11015.17 SOD {03:03:35.17} UT,   876.0 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.135
N_STARS:         161
X_OFFSET:        427 [pixels]
Y_OFFSET:        176 [pixels]
X_MAX:           1866 [pixels]
Y_MAX:           1615 [pixels]
DET_THRESH:      15
PHOTO_THRESH:    8
SL_URL:          sw01001514000msufc0876.fits
SUN_POSTN:       209.03d {+13h 56m 08s}  -11.88d {-11d 52' 47"}
SUN_DIST:         83.70 [deg]   Sun_angle= 5.5 [hr] (West of Sun)
MOON_POSTN:      311.55d {+20h 46m 11s}  -21.83d {-21d 49' 34"}
MOON_DIST:       160.77 [deg]
MOON_ILLUM:      56 [%]
GAL_COORDS:      220.73, 22.01 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      127.42,-15.52 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 24 Oct 20 03:07:27 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1001514,   Seg_Num: 0
POINT_RA:        125.915d {+08h 23m 40s} (J2000)
POINT_DEC:        +3.380d {+03d 22' 48"} (J2000)
POINT_ROLL:      102.329d
IMG_START_DATE:  19146 TJD;   298 DOY;   20/10/24
IMG_START_TIME:  11015.17 SOD {03:03:35.17} UT,   876.0 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        3.135
N_STARS:         161
X_OFFSET:        427 [pixels]
Y_OFFSET:        176 [pixels]
X_MAX:           1866 [pixels]
Y_MAX:           1615 [pixels]
DET_THRESH:      15
PHOTO_THRESH:    8
SL_URL:          sw01001514000msufc0876.fits
SUN_POSTN:       209.03d {+13h 56m 08s}  -11.88d {-11d 52' 47"}
SUN_DIST:         83.70 [deg]   Sun_angle= 5.5 [hr] (West of Sun)
MOON_POSTN:      311.55d {+20h 46m 12s}  -21.83d {-21d 49' 32"}
MOON_DIST:       160.77 [deg]
MOON_ILLUM:      56 [%]
GAL_COORDS:      220.73, 22.01 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      127.42,-15.52 [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:     Wed 21 Oct 20 20:43:35 UT
NOTICE_TYPE:     Swift-UVOT Processed 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 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:     Sat 24 Oct 20 02:51:00 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     1001514,   Seg_Num: 0
GRB_RA:          125.9507d {+08h 23m 48.1s} (J2000),
                 126.2228d {+08h 24m 53.4s} (current),
                 125.2966d {+08h 21m 11.1s} (1950)
GRB_DEC:          +3.3549d {+03d 21' 17.6"} (J2000),
                  +3.2867d {+03d 17' 11.9"} (current),
                  +3.5171d {+03d 31' 01.4"} (1950)
GRB_ERROR:       5.8 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       31 [cnts]
IMG_START_DATE:  19146 TJD;   298 DOY;   20/10/24
IMG_START_TIME:  10214.02 SOD {02:50:14.02} UT,   74.9 [sec] since BAT Trigger Time
CENTROID_X:      249.50,  raw= 250  [pixels]
CENTROID_Y:      271.93,  raw= 272  [pixels]
ROLL:            102.33 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -61.66
GRB_POS_XRT_Z:   -136.47
IMAGE_URL:       sw01001514000msxps_rw.img
SUN_POSTN:       209.02d {+13h 56m 05s}  -11.88d {-11d 52' 33"}
SUN_DIST:         83.65 [deg]   Sun_angle= 5.5 [hr] (West of Sun)
MOON_POSTN:      311.39d {+20h 45m 34s}  -21.86d {-21d 51' 18"}
MOON_DIST:       160.76 [deg]
MOON_ILLUM:      56 [%]
GAL_COORDS:      220.77, 22.03 [deg] galactic lon,lat of the burst
ECL_COORDS:      127.47,-15.53 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN Circular #28760
V. Lipunov, N.Tyurina, E. Gorbovskoy, V.Kornilov, 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. 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),
R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA),
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 GRB201024A (trigger 1001514) 36 sec after notice time and 66 sec after trigger time at 2020-10-24 02:51:20 UT. On our first (10s exposure) set we found 1 optical transient within Swift error-box (ra=125.95 dec=3.35444 r=0.05) brighter than 16.5.
```
  T-Tmid      Date      Time       Expt.        Ra                Dec         Mag
---------|---------------------|-------|-----------------|-----------------|-----
      229   2020-09-25 21:54:16     40   (08h 23m 48.58s,   +03d 21m 13.8s) 14.9
```
The 5-sigma upper limit has been about 17mag The message may be cited.
GCN Circular #28761
F. E. Marshall (NASA/GSFC), M. G. Bernardini (INAF-OAB), P. D'Avanzo (INAF-OAB), J.D. Gropp (PSU), N. J. Klingler (PSU), N. P. M. Kuin (UCL-MSSL), S. Laha (GSFC/UMBC/CRESST), A. Melandri (INAF-OAB), D. M. Palmer (LANL), T. Sbarrato (INAF-OAB) and A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift Observatory Team:
At 02:48:59 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 201024A (trigger=1001514). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 125.948, +3.377 which is
```
   RA(J2000) = 08h 23m 47s
   Dec(J2000) = +03d 22' 38"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single peak structure with a duration of about 5 sec. The peak count rate was ~1200 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 02:50:14.0 UT, 74.9 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source with an enhanced position: RA, Dec 125.9521, 3.3537 which is equivalent to:
```
   RA(J2000)  = 08h 23m 48.50s
   Dec(J2000) = +03d 21' 13.4"
```
with an uncertainty of 2.1 arcseconds (radius, 90% containment). This location is 85 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 3.64 x 10^20 cm^-2 (Willingale et al. 2013).
The initial flux in the 2.5 s image was 6.41e-10 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 495 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at
```
  RA(J2000)  =	08:23:48.55 = 125.95229
  DEC(J2000) = +03:21:14.5  =	3.35403
```
with a 90%-confidence error radius of about 0.62 arc sec. This position is 0.7 arc sec. from the center of the XRT error circle. The estimated magnitude is 17.85 with a 1-sigma error of about 0.14. No correction has been made for the expected extinction corresponding to E(B-V) of 0.03.
Burst Advocate for this burst is F. E. Marshall (marshall AT milkyway.gsfc.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 #28762
GRB 201024A: MASTER correction to GCN 28760
Due to a typo, the OT datetime data in the table (GCN 28760) was wrong Here are the correct values
```
  T-Tmid      Date      Time       Expt.        Ra                Dec         Mag
---------|---------------------|-------|-----------------|-----------------|-----
       66   2020-10-24 02:51:20     10   (08h 23m 48.58s,   +03d 21m 13.8s) 14.9
```
The OT position is coincident with UVOT and XRT position. The afterglow appears to be fading rapidly.
GCN Circular #28763
E. Fernandez-Garcia, Y.-D. Hu, A. J. Castro-Tirado, A. Sota (IAA-CSIC), C. Perez del Pulgar, A. Castellon, I. Carrasco (Univ. de Malaga), R. Fernandez-Munoz (IHSM/UMA-CSIC), M.D. Caballero-Garcia and M. Jelinek (ASU-CAS), on behalf of a larger collaboration, report:
The 0.6m BOOTES-2/TELMA robotic telescope at IHSM La Mayora (UMA-CSIC) in Algarrobo Costa (Malaga, Spain) automatically responded to the Swift trigger of GRB 201024A (Marshall et al. GCNC 28761). A series of images were taken starting on Oct 24 at Oct 02:50:07 UT (~68 s after trigger). A bright optical source is detected on the first image (10s, clear filter) with r= 14.1 mag, at a position consistent with the optical afterglow reported by UVOT/Swift (Marshall et al. GCNC 28761) and MASTER (Lipunov et al. GCNC 28760).
Furthermore, from a deeper image gathered at the 1.5m OSN telescope in Observatorio de Sierra Nevada at 03:16 UT we measure R = 18.9, thus confirming the rapid fading of the optical afterglow brightness as pointed out on GCNC 28762.
Additional observations are ongoing. We thank the staff at La Mayora and OSN for their excellent support.
GCN Circular #28764
A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), D. A. Kann, M. Blazek, J. F. Agui Fernandez, C. C. Thoene (all HETH/IAA-CSIC), S. Geier, and M. Rivero (both GRANTECAN) report:
We observed the afterglow (Lipunov et al., GCN#28760, Marshall et al., GCN#28761, Fernandez-Garcia et al., GCN#28763) of GRB 201024A (Marshall et al., GCN#28761) with the 10.4m GTC telescope, at Roque de los Muchachos Observatory (La Palma, Spain) equipped with OSIRIS. The observation started on 24 October 2020 at 03:28:47 UT (0.663 hrs after the GRB onset) and consisted of 3 x 900 s with the R1000B grism, covering the wavelength range between 3700 and 7800 AA. Observations were taken under good conditions but high airmass.
At the afterglow position, a clear source is detected. We measure r' ~ 19.3 mag (AB) vs. nearby PanSTARRS field stars. This indicates the source has faded rapidly vs. the early MASTER/BOOTES detection, as Lipunov et al., GCN#28760 and Fernandez-Garcia et al., GCN#28763 stated.
A preliminary reduction of the spectrum shows a clear continuum, with MnII, FeII, FeII*, MgII, and MgI absorption lines, as well as the [OII] doublet in emission, all at a common redshift of z = 0.999, which we identify as the redshift of the GRB.
We furthermore note that there is an underlying galaxy at the OT position visible in SDSS and PanSTARRS, at r ~ 21.15 mag. We also see a second galaxy offset by a few arcsec in our finding chart.
We thank P. D'Avanzo and L. Izzo for pointing out the galaxy.
GCN Circular #28766
Martin Jelinek and Jan Strobl (ASU CAS Ondrejov, CZ), Sergey Karpov, Martin Masek, Petr Janecek, Jakub Jurysek, Jan Ebr, Ronan Cunniffe, Petr Travnicek and Michael Prouza (Institute of Physics, Prague, CZ)
report:
The 25cm robotic telescope FRAM-ORM at La Palma (Spain) reacted robotically to the alert of GRB201024A (Marshall et al GCNC 28761), obtaining a series of 20 s unfiltered images starting at 02:49:34.4 UT, i.e. 35.3s post trigger.
We clearly detect the source reported by other telescopes (Lipunov et al. GCN 28760, Fernandez-Garcia et al. GCN 28763, de Ugarte Postigo et al GCN 28764 and others). As reported before, the brightness of the object reaches a maximum of about R(Vega) = 14.0 and then decays relatively steeply with a power law index alpha = ~1.5.
GCN Circular #28770
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team.
Using 890 s of XRT Photon Counting mode data and 3 UVOT images for GRB 201024A, 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 = 125.95224, +3.35444 which is equivalent to:
```
RA (J2000): 08h 23m 48.54s
Dec (J2000): +03d 21' 16.0"
```
with an uncertainty of 2.7 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 #28771
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 GRB201024A (F. E. Marchall et al., GCN 28761) with the 0.5m Virgin Island Robotic Telescope (VIRT) at the University of the Virgin Islands' Etelman Observatory on 10-24-2020 starting at 06:39:34.2 UT (T+3.3 hrs). We performed a series of exposures in R filter with a total exposure of 1430 s. The weather conditions were partly cloudy during the hours of
observation with an average arimass of 1.5.
We find no new source within the enhanced XRT position error circle (P. A. Evans et al., 28770) and report the following 3-sigma upper limit:
```
T_mid       ||Exposure     ||Filter      ||Limit
T+ 5 hrs    ||1430s          ||R            ||>18.9
```
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 #28774
N. P. M. Kuin (UCL-MSSL) and F. E. Marshall (NASA/GSFC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 201024A 495 s after the BAT trigger (Marshall et al., GCN Circ. 28761). A source consistent with the XRT position (Evans et al. GCN Circ. 28770) is detected in the initial UVOT exposures.
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              495          645          148         17.94 +/- 0.05
v                  653          845           39         17.39 +/- 0.30
b                  750         1348           58         18.65 +/- 0.32
u                  726         1151           39         17.86 +/- 0.29
w1                 702         1471           78         17.46 +/- 0.30
m2                 677         2140          117        >18.4
w2                 801         2091          117        >17.7
```
The observations show a rapid decay as reported by MASTER (Lipunov et al, GCN Circ. No. 28762). The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.03 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #28775
A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-IASFPA), J. D. Gropp (PSU), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto) and F.E. Marshall report on behalf of the Swift-XRT team:
We have analysed 6.0 ks of XRT data for GRB 201024A (Marshall et al. GCN Circ. 28761), from 450 s to 48.0 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN Circ. 28770).
The light curve can be modelled with a power-law decay with a decay index of alpha=0.98 (+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 2.08 (+0.19, -0.18). The best-fitting absorption column is 1.7 (+0.6, -0.5) x 10^21 cm^-2, in excess of the Galactic value of 3.6 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 3.3 x 10^-11 (4.6 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     1.7 (+0.6, -0.5) x 10^21 cm^-2
Galactic foreground: 3.6 x 10^20 cm^-2
Excess significance: 4.1 sigma
Photon index:	     2.08 (+0.19, -0.18)
```
If the light curve continues to decay with a power-law decay index of 0.98, the count rate at T+24 hours will be 5.7 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.9 x 10^-13 (2.6 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/01001514.
This circular is an official product of the Swift-XRT team.
GCN Circular #28777
Paul Kuin (UCL/MSSL) reports on behalf of the Swift UVOT Team:
We now have the light curve of GRB 201024A in the seven UVOT filters from the start of our observations T0+495s until T0+100ks. After a steep decline a rebrightening is seen starting around T0+1400s which then peaks between 20 and 70 ks.
GCN Circular #28778
T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), F. E. Marshall (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), (i.e. the Swift-BAT team):
Using the data set from T-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 201024A (trigger #1001514) (F. E. Marshall et al., GCN Circ. 28761). The BAT ground-calculated position is RA, Dec = 125.959, 3.357 deg which is
```
   RA(J2000)  =  08h 23m 50.3s
   Dec(J2000) = +03d 21' 24.6"
```
with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 22%.
The BAT light curve showed a single peak structure with a duration of about 6 sec. T90 (15-350 keV) is 5.00 +- 2.24 sec (estimated error including systematics).
The time-averaged spectrum from T+0.01 to T+6.01 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.10 +- 0.18. The fluence in the 15-150 keV band is 8.1 +- 0.9 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T+1.01 sec in the 15-150 keV band is 3.7 +- 0.6 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/1001514/BA/
GCN Circular #28779
M. Niwano, K. L. Murata, R. Hosokawa, R. Adachi, 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 201024A (F. E. Marshall et al.,GCN Circular #28761) with the optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan.
We observed for two nights. The observation with a series of 60 sec exposures started at 2020-10-24 16:04:04UT for the first night and 2020-10-25 15:56:17UT for the second night. We stacked the images with good conditions each night. We did not detect the point source reported by other telescopes (Lipunov et al. GCN Circular #28760, Fernandez-Garcia et al. #28763, de Ugarte Postigo et al. #28764, Martin Jelinek et al. #28766). We obtained the 5-sigma limits of the stacked images as follows.
```
T0+[hour] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
13.78 2020-10-24T18:27:11 11520 g'>20.2, Rc>20.4, Ic>19.7
38.48 2020-10-25T17:17:59 1980 g'>19.4, Rc>19.6, Ic>18.8
------------------------------------------------------------------------------------------------
T0+: Elapsed time after the burst
T-EXP: Total Exposure time
```
We used the 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 #28780
Paul Kuin (UCL/MSSLL) reports:
Due to an incorrect background subtraction in the later exposures of GRB201024A, an incorrect 'rebrightening' was found in the Swift-UVOT photometry. In actuality the source had faded away.
My sincere apologies if this has caused any problems.
GCN Circular #28782
Rahul Gupta (ARIES), Amit Kumar (ARIES), Dimple (ARIES), Ankur Ghosh (ARIES), Amar Aryan (ARIES), Shashi B. Pandey (ARIES), and Kuntal Misra (ARIES) report:
We observed the optical afterglow ( Lipunov et al., GCN 28760; Marshall et al., GCN 28761; Fernandez-Garcia et al., GCN 28763; de Ugarte Postigo et al., GCN 28764; Jelinek et al., GCN 28766; and Kuin et al., GCN 28774 ) of Swift triggered GRB 201024A (Marshall et al., GCN 28761) using the 1.3m Devasthal Fast Optical Telescope (DFOT) at Devasthal observatory of Aryabhatta Research Institute of Observational Sciences (ARIES), India. The observations were started on 2020-10-24 at 21:03:09 UT . Multiple frames having an exposure time of 120 s were taken in R and I filters. We clearly detected the optical counterpart in the stacked images.
The preliminary photometric estimate of the afterglow in the stacked images is the following :
```
Date Start_UT T_start-T0 (hrs) Filter Exp time (s) Magnitude Mag_err 
------------------------------ ------------------------------ ------------------------------ ------------------------------ ------------------------------------------------ 

2020-10-24 21:03:09 18.24 I 30*120 20.12 0.07 

------------------------------ ------------------------------ ------------------------------ ------------------------------ ------------------------------------------------ 
```
The magnitude is not corrected for the Galactic and Host extinction in the direction of the burst. Photometric calibration is performed using the standard stars from the USNO-B1.0 catalog.
This circular may be cited.

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Jochen Greiner, last update: 26-Oct-2020 [Disclaimer]