Gamma-ray Burst 201027A

(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 27 Oct 20 01:08:02 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1002158,   Seg_Num: 0
GRB_RA:          155.974d {+10h 23m 54s} (J2000),
                 156.236d {+10h 24m 57s} (current),
                 155.345d {+10h 21m 23s} (1950)
GRB_DEC:          -5.515d {-05d 30' 53"} (J2000),
                  -5.621d {-05d 37' 14"} (current),
                  -5.261d {-05d 15' 39"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       3249 [cnts]    Image_Peak=149 [image_cnts]
TRIGGER_DUR:     1.024 [sec] 
TRIGGER_INDEX:   148     E_range: 25-100 keV
BKG_INTEN:       19778 [cnts]
BKG_TIME:        4046.12 SOD {01:07:26.12} UT
BKG_DUR:         8 [sec]
GRB_DATE:        19149 TJD;   301 DOY;   20/10/27
GRB_TIME:        4064.17 SOD {01:07:44.17} UT
GRB_PHI:         -78.54 [deg]
GRB_THETA:        31.30 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     15.39 [sigma]
IMAGE_SIGNIF:    8.12 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +2  -2  +0  +0 -56  +0 
SUN_POSTN:       211.83d {+14h 07m 19s}  -12.88d {-12d 52' 37"}
SUN_DIST:         55.25 [deg]   Sun_angle= 3.7 [hr] (West of Sun)
MOON_POSTN:      347.48d {+23h 09m 56s}  -10.93d {-10d 55' 42"}
MOON_DIST:       160.02 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      249.83, 41.66 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      159.85,-14.44 [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 = 71.35,-17.78 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 27 Oct 20 01:09:17 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     1002158,   Seg_Num: 0
POINT_RA:        155.942d {+10h 23m 46s} (J2000)
POINT_DEC:        -5.519d {-05d 31' 07"} (J2000)
IMG_START_DATE:  19149 TJD;   301 DOY;   20/10/27
IMG_START_TIME:  4147.59 SOD {01:09:07.59} UT,   83.4 [sec] since BAT Trigger Time
COUNTS:          1    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        0    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:     Tue 27 Oct 20 01:11:46 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1002158,   Seg_Num: 0
GRB_RA:          155.974d {+10h 23m 54s} (J2000),
                 156.236d {+10h 24m 57s} (current),
                 155.345d {+10h 21m 23s} (1950)
GRB_DEC:          -5.515d {-05d 30' 53"} (J2000),
                  -5.621d {-05d 37' 14"} (current),
                  -5.261d {-05d 15' 39"} (1950)
GRB_DATE:        19149 TJD;   301 DOY;   20/10/27
GRB_TIME:        4064.17 SOD {01:07:44.17} UT
TRIGGER_INDEX:   148
GRB_PHI:         -78.54 [deg]
GRB_THETA:        31.30 [deg]
DELTA_TIME:      -44.00 [sec]
TRIGGER_DUR:     1.024 [sec] 
SOLN_STATUS:     0x3
RATE_SIGNIF:     15.39 [sigma]
IMAGE_SIGNIF:    8.12 [sigma]
LC_URL:          sw01002158000msb.lc
SUN_POSTN:       211.83d {+14h 07m 19s}  -12.88d {-12d 52' 40"}
SUN_DIST:         55.25 [deg]   Sun_angle= 3.7 [hr] (West of Sun)
MOON_POSTN:      347.51d {+23h 10m 03s}  -10.92d {-10d 55' 00"}
MOON_DIST:       160.01 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      249.83, 41.66 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      159.85,-14.44 [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 = 71.35,-17.78 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 26 Oct 20 22:52:05 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1002103,   Seg_Num: 0
POINT_RA:        196.693d {+13h 06m 46s} (J2000)
POINT_DEC:       +83.745d {+83d 44' 40"} (J2000)
ROLL:            165.267d
IMG_START_DATE:  19148 TJD;   300 DOY;   20/10/26
IMG_START_TIME:  81541.99 SOD {22:39:01.99} UT,   87.8 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     625444767
X_OFFSET:        507 [pixels]
Y_OFFSET:        922 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       667
Y_GRB_POS:       1082
BINNING_INDEX:   1
IM_URL:          sw01002103000msuni0113.fits
SUN_POSTN:       211.74d {+14h 06m 57s}  -12.85d {-12d 50' 43"}
SUN_DIST:         96.69 [deg]   Sun_angle= 1.0 [hr] (West of Sun)
MOON_POSTN:      346.41d {+23h 05m 39s}  -11.36d {-11d 21' 31"}
MOON_DIST:       106.84 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      122.43, 33.37 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      105.89, 67.59 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 27 Oct 20 01:13:11 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1002158,   Seg_Num: 0
POINT_RA:        155.941d {+10h 23m 46s} (J2000)
POINT_DEC:        -5.519d {-05d 31' 07"} (J2000)
POINT_ROLL:      101.867d
IMG_START_DATE:  19149 TJD;   301 DOY;   20/10/27
IMG_START_TIME:  4150.84 SOD {01:09:10.84} UT,   86.7 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.723
N_STARS:         27
X_OFFSET:        653 [pixels]
Y_OFFSET:        372 [pixels]
X_MAX:           1612 [pixels]
Y_MAX:           1331 [pixels]
DET_THRESH:      18
PHOTO_THRESH:    10
SL_URL:          sw01002158000msufc0086.fits
SUN_POSTN:       211.83d {+14h 07m 20s}  -12.88d {-12d 52' 42"}
SUN_DIST:         55.28 [deg]   Sun_angle= 3.7 [hr] (West of Sun)
MOON_POSTN:      347.52d {+23h 10m 06s}  -10.91d {-10d 54' 43"}
MOON_DIST:       159.99 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      249.80, 41.64 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      159.82,-14.46 [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:     Tue 27 Oct 20 01:14:57 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1002158,   Seg_Num: 0
POINT_RA:        155.941d {+10h 23m 46s} (J2000)
POINT_DEC:        -5.519d {-05d 31' 07"} (J2000)
ROLL:            101.867d
IMG_START_DATE:  19149 TJD;   301 DOY;   20/10/27
IMG_START_TIME:  4150.84 SOD {01:09:10.84} UT,   86.7 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     625453776
X_OFFSET:        972 [pixels]
Y_OFFSET:        691 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1132
Y_GRB_POS:       851
BINNING_INDEX:   1
IM_URL:          sw01002158000msuni0112.fits
SUN_POSTN:       211.83d {+14h 07m 20s}  -12.88d {-12d 52' 43"}
SUN_DIST:         55.28 [deg]   Sun_angle= 3.7 [hr] (West of Sun)
MOON_POSTN:      347.54d {+23h 10m 09s}  -10.91d {-10d 54' 23"}
MOON_DIST:       159.99 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      249.80, 41.64 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      159.82,-14.46 [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:     Mon 26 Oct 20 22:59:47 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1002103,   Seg_Num: 0
POINT_RA:        196.710d {+13h 06m 50s} (J2000)
POINT_DEC:       +83.745d {+83d 44' 41"} (J2000)
POINT_ROLL:      165.283d
IMG_START_DATE:  19148 TJD;   300 DOY;   20/10/26
IMG_START_TIME:  82333.43 SOD {22:52:13.43} UT,   879.2 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        0.262
N_STARS:         92
X_OFFSET:        0 [pixels]
Y_OFFSET:        362 [pixels]
X_MAX:           1439 [pixels]
Y_MAX:           1801 [pixels]
DET_THRESH:      5
PHOTO_THRESH:    2
SL_URL:          sw01002103000msufc0879.fits
SUN_POSTN:       211.74d {+14h 06m 58s}  -12.85d {-12d 50' 49"}
SUN_DIST:         96.70 [deg]   Sun_angle= 1.0 [hr] (West of Sun)
MOON_POSTN:      346.47d {+23h 05m 53s}  -11.33d {-11d 20' 04"}
MOON_DIST:       106.82 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      122.43, 33.37 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      105.89, 67.59 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 27 Oct 20 01:15:08 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     1002158,   Seg_Num: 0
GRB_RA:          155.9691d {+10h 23m 52.58s} (J2000),
                 156.2313d {+10h 24m 55.51s} (current),
                 155.3394d {+10h 21m 21.45s} (1950)
GRB_DEC:          -5.5087d {-05d 30' 31.3"} (J2000),
                  -5.6147d {-05d 36' 52.8"} (current),
                  -5.2551d {-05d 15' 18.1"} (1950)
GRB_ERROR:       4.9 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  19149 TJD;   301 DOY;   20/10/27
IMG_START_TIME:  4325.00 SOD {01:12:05.00} UT,   260.8 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       211.83d {+14h 07m 20s}  -12.88d {-12d 52' 43"}
SUN_DIST:         55.26 [deg]   Sun_angle= 3.7 [hr] (West of Sun)
MOON_POSTN:      347.54d {+23h 10m 09s}  -10.91d {-10d 54' 21"}
MOON_DIST:       160.01 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      249.82, 41.66 [deg] galactic lon,lat of the burst
ECL_COORDS:      159.84,-14.44 [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 Circular #28787
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 GRB201027.05 (trigger No 1002158,10h 23m 53.76s , -05d 30m 54.0s, R=0.05) errorbox 50 sec after trigger time at 2020-10-27 01:08:34 UT, with upper limit up to 15.6 mag. The observations began at zenith distance = 81 deg. The sun altitude is -30.2 deg.
The galactic latitude b = 42 deg., longitude l = 251 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1469802
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

      55 |         MASTER-SAAO |  P/ |    10 | 15.6 |        
```
The observation and reduction will continue. The message may be cited.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 26 Oct 20 23:00:55 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1002103,   Seg_Num: 0
POINT_RA:        196.710d {+13h 06m 50s} (J2000)
POINT_DEC:       +83.745d {+83d 44' 41"} (J2000)
ROLL:            165.283d
IMG_START_DATE:  19148 TJD;   300 DOY;   20/10/26
IMG_START_TIME:  82333.43 SOD {22:52:13.43} UT,   879.2 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     625445559
X_OFFSET:        559 [pixels]
Y_OFFSET:        921 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       719
Y_GRB_POS:       1081
BINNING_INDEX:   1
IM_URL:          sw01002103000msuni0905.fits
SUN_POSTN:       211.74d {+14h 06m 58s}  -12.85d {-12d 50' 50"}
SUN_DIST:         96.70 [deg]   Sun_angle= 1.0 [hr] (West of Sun)
MOON_POSTN:      346.48d {+23h 05m 55s}  -11.33d {-11d 19' 51"}
MOON_DIST:       106.81 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      122.43, 33.37 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      105.89, 67.59 [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 27 Oct 20 01:21:21 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1002158,   Seg_Num: 0
POINT_RA:        155.939d {+10h 23m 45s} (J2000)
POINT_DEC:        -5.518d {-05d 31' 04"} (J2000)
POINT_ROLL:      101.867d
IMG_START_DATE:  19149 TJD;   301 DOY;   20/10/27
IMG_START_TIME:  4362.71 SOD {01:12:42.71} UT,   298.5 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        1.413
N_STARS:         46
X_OFFSET:        413 [pixels]
Y_OFFSET:        132 [pixels]
X_MAX:           1852 [pixels]
Y_MAX:           1571 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw01002158000msufc0298.fits
SUN_POSTN:       211.84d {+14h 07m 21s}  -12.88d {-12d 52' 48"}
SUN_DIST:         55.29 [deg]   Sun_angle= 3.7 [hr] (West of Sun)
MOON_POSTN:      347.59d {+23h 10m 21s}  -10.89d {-10d 53' 10"}
MOON_DIST:       159.97 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      249.80, 41.63 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      159.82,-14.46 [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:     Tue 27 Oct 20 01:22:33 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1002158,   Seg_Num: 0
POINT_RA:        155.939d {+10h 23m 45s} (J2000)
POINT_DEC:        -5.518d {-05d 31' 04"} (J2000)
ROLL:            101.867d
IMG_START_DATE:  19149 TJD;   301 DOY;   20/10/27
IMG_START_TIME:  4362.71 SOD {01:12:42.71} UT,   298.5 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     625453988
X_OFFSET:        972 [pixels]
Y_OFFSET:        691 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1132
Y_GRB_POS:       851
BINNING_INDEX:   1
IM_URL:          sw01002158000msuni0324.fits
SUN_POSTN:       211.84d {+14h 07m 21s}  -12.88d {-12d 52' 49"}
SUN_DIST:         55.29 [deg]   Sun_angle= 3.7 [hr] (West of Sun)
MOON_POSTN:      347.60d {+23h 10m 23s}  -10.88d {-10d 52' 56"}
MOON_DIST:       159.97 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      249.80, 41.63 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      159.82,-14.46 [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 27 Oct 20 01:21:30 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     1002158,   Seg_Num: 0
GRB_RA:          155.9699d {+10h 23m 52.77s} (J2000),
                 156.2321d {+10h 24m 55.70s} (current),
                 155.3402d {+10h 21m 21.64s} (1950)
GRB_DEC:          -5.5101d {-05d 30' 36.3"} (J2000),
                  -5.6161d {-05d 36' 57.8"} (current),
                  -5.2565d {-05d 15' 23.2"} (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:  19149 TJD;   301 DOY;   20/10/27
IMG_START_TIME:  4325.00 SOD {01:12:05.00} UT,   260.8 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       211.84d {+14h 07m 21s}  -12.88d {-12d 52' 49"}
SUN_DIST:         55.26 [deg]   Sun_angle= 3.7 [hr] (West of Sun)
MOON_POSTN:      347.59d {+23h 10m 21s}  -10.89d {-10d 53' 08"}
MOON_DIST:       160.00 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      249.82, 41.66 [deg] galactic lon,lat of the burst
ECL_COORDS:      159.84,-14.44 [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 NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 27 Oct 20 01:12:56 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1002158,   Seg_Num: 0
POINT_RA:        155.941d {+10h 23m 46s} (J2000)
POINT_DEC:        -5.519d {-05d 31' 07"} (J2000)
POINT_ROLL:      101.867d
IMG_START_DATE:  19149 TJD;   301 DOY;   20/10/27
IMG_START_TIME:  4150.84 SOD {01:09:10.84} UT,   86.7 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.723
N_STARS:         27
X_OFFSET:        653 [pixels]
Y_OFFSET:        372 [pixels]
X_MAX:           1612 [pixels]
Y_MAX:           1331 [pixels]
DET_THRESH:      18
PHOTO_THRESH:    10
SL_URL:          sw01002158000msufc0086.fits
SUN_POSTN:       211.83d {+14h 07m 20s}  -12.88d {-12d 52' 41"}
SUN_DIST:         55.28 [deg]   Sun_angle= 3.7 [hr] (West of Sun)
MOON_POSTN:      347.52d {+23h 10m 05s}  -10.91d {-10d 54' 46"}
MOON_DIST:       159.99 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      249.80, 41.64 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      159.82,-14.46 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN Circular #28788
S. B. Cenko (GSFC), S. D. Barthelmy (GSFC), M. G. Bernardini (INAF-OAB), P. D'Avanzo (INAF-OAB), N. J. Klingler (PSU), 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 01:07:44 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 201027A (trigger=1002158). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 155.974, -5.515 which is
```
   RA(J2000) = 10h 23m 54s
   Dec(J2000) = -05d 30' 53"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 20 sec. The peak count rate was ~1500 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 01:09:07.5 UT, 83.4 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source with an enhanced position: RA, Dec 155.9700, -5.5101 which is equivalent to:
```
   RA(J2000)  = 10h 23m 52.81s
   Dec(J2000) = -05d 30' 36.2"
```
with an uncertainty of 2.3 arcseconds (radius, 90% containment). This location is 22 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 in excess of the Galactic value (4.67 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 2.6 (+2.14/-1.93) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 86 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.04.
Burst Advocate for this burst is S. B. Cenko (brad.cenko 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 NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Tue 27 Oct 20 01:27:57 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1002158,   Seg_Num: 0
POINT_RA:        155.939d {+10h 23m 45s} (J2000)
POINT_DEC:        -5.518d {-05d 31' 04"} (J2000)
POINT_ROLL:      101.866d
IMG_START_DATE:  19149 TJD;   301 DOY;   20/10/27
IMG_START_TIME:  4943.19 SOD {01:22:23.19} UT,   879.0 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        4.970
N_STARS:         72
X_OFFSET:        413 [pixels]
Y_OFFSET:        132 [pixels]
X_MAX:           1852 [pixels]
Y_MAX:           1571 [pixels]
DET_THRESH:      19
PHOTO_THRESH:    11
SL_URL:          sw01002158000msufc0879.fits
SUN_POSTN:       211.84d {+14h 07m 22s}  -12.88d {-12d 52' 54"}
SUN_DIST:         55.29 [deg]   Sun_angle= 3.7 [hr] (West of Sun)
MOON_POSTN:      347.64d {+23h 10m 33s}  -10.87d {-10d 51' 54"}
MOON_DIST:       159.96 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      249.80, 41.63 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      159.82,-14.46 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

 
TITLE:           GCN/SWIFT NOTICE 
NOTICE_DATE:     Tue 27 Oct 20 01:28:14 UT 
NOTICE_TYPE:     Swift-UVOT Processed Source List 
TRIGGER_NUM:     1002158,   Seg_Num: 0 
POINT_RA:        155.939d {+10h 23m 45s} (J2000) 
POINT_DEC:        -5.518d {-05d 31' 04"} (J2000) 
POINT_ROLL:      101.866d 
IMG_START_DATE:  19149 TJD;   301 DOY;   20/10/27 
IMG_START_TIME:  4943.19 SOD {01:22:23.19} UT,   879.0 [sec] since BAT Trigger Time 
FILTER:          10, White 
BKG_MEAN:        4.970 
N_STARS:         72 
X_OFFSET:        413 [pixels] 
Y_OFFSET:        132 [pixels] 
X_MAX:           1852 [pixels] 
Y_MAX:           1571 [pixels] 
DET_THRESH:      19 
PHOTO_THRESH:    11 
SL_URL:          sw01002158000msufc0879.fits 
SUN_POSTN:       211.84d {+14h 07m 22s}  -12.88d {-12d 52' 54"} 
SUN_DIST:         55.29 [deg]   Sun_angle= 3.7 [hr] (West of Sun) 
MOON_POSTN:      347.64d {+23h 10m 34s}  -10.86d {-10d 51' 51"} 
MOON_DIST:       159.96 [deg] 
MOON_ILLUM:      82 [%] 
GAL_COORDS:      249.80, 41.63 [deg] galactic lon,lat of the pointing direction 
ECL_COORDS:      159.82,-14.46 [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:     Tue 27 Oct 20 01:15:07 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1002158,   Seg_Num: 0
POINT_RA:        155.941d {+10h 23m 46s} (J2000)
POINT_DEC:        -5.519d {-05d 31' 07"} (J2000)
ROLL:            101.867d
IMG_START_DATE:  19149 TJD;   301 DOY;   20/10/27
IMG_START_TIME:  4150.84 SOD {01:09:10.84} UT,   86.7 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     625453776
X_OFFSET:        972 [pixels]
Y_OFFSET:        691 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1132
Y_GRB_POS:       851
BINNING_INDEX:   1
IM_URL:          sw01002158000msuni0112.fits
SUN_POSTN:       211.83d {+14h 07m 20s}  -12.88d {-12d 52' 43"}
SUN_DIST:         55.28 [deg]   Sun_angle= 3.7 [hr] (West of Sun)
MOON_POSTN:      347.54d {+23h 10m 09s}  -10.91d {-10d 54' 21"}
MOON_DIST:       159.99 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      249.80, 41.64 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      159.82,-14.46 [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 27 Oct 20 01:30:00 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1002158,   Seg_Num: 0
POINT_RA:        155.939d {+10h 23m 45s} (J2000)
POINT_DEC:        -5.518d {-05d 31' 04"} (J2000)
ROLL:            101.866d
IMG_START_DATE:  19149 TJD;   301 DOY;   20/10/27
IMG_START_TIME:  4943.19 SOD {01:22:23.19} UT,   879.0 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     625454569
X_OFFSET:        972 [pixels]
Y_OFFSET:        691 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1132
Y_GRB_POS:       851
BINNING_INDEX:   1
IM_URL:          sw01002158000msuni0905.fits
SUN_POSTN:       211.84d {+14h 07m 22s}  -12.88d {-12d 52' 56"}
SUN_DIST:         55.29 [deg]   Sun_angle= 3.7 [hr] (West of Sun)
MOON_POSTN:      347.66d {+23h 10m 37s}  -10.86d {-10d 51' 31"}
MOON_DIST:       159.96 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      249.80, 41.63 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      159.82,-14.46 [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 27 Oct 20 01:30:15 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1002158,   Seg_Num: 0
POINT_RA:        155.939d {+10h 23m 45s} (J2000)
POINT_DEC:        -5.518d {-05d 31' 04"} (J2000)
ROLL:            101.866d
IMG_START_DATE:  19149 TJD;   301 DOY;   20/10/27
IMG_START_TIME:  4943.19 SOD {01:22:23.19} UT,   879.0 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     625454569
X_OFFSET:        972 [pixels]
Y_OFFSET:        691 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1132
Y_GRB_POS:       851
BINNING_INDEX:   1
IM_URL:          sw01002158000msuni0905.fits
SUN_POSTN:       211.84d {+14h 07m 22s}  -12.88d {-12d 52' 56"}
SUN_DIST:         55.29 [deg]   Sun_angle= 3.7 [hr] (West of Sun)
MOON_POSTN:      347.66d {+23h 10m 38s}  -10.86d {-10d 51' 28"}
MOON_DIST:       159.96 [deg]
MOON_ILLUM:      82 [%]
GAL_COORDS:      249.80, 41.63 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      159.82,-14.46 [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 Circular #28792
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team.
Using 1722 s of XRT Photon Counting mode data and 2 UVOT images for GRB 201027A, 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 = 155.96975, -5.51002 which is equivalent to:
```
RA (J2000): 10h 23m 52.74s
Dec (J2000): -05d 30' 36.1"
```
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 #28794
Y.-D. Hu, F. J. Aceituno, A. J. Castro-Tirado, E. Fernandez-Garcia (IAA-CSIC) on behalf of a larger collaboration, report:
Following the detection of GRB201027A by Swift (Cenko et al. GCNC 28788), optical images in the I-band were obtained at the 1.5m OSN telescope in Granada (Spain) starting at 04:29 (Oct 27), i.e. ~3.4 h post burst. No optical afterglow is detected in the co-added image within the enhanced Swift/XRT error box (Osborne et al. GCNC 28792) down to I=21.9, which is consistent with the non-detection reported by Swift/UVOT (GCNC 28788).
We thank the staff at OSN for their excellent support.
GCN Circular #28798
J.P. Osborne (U. Leicester), M. Capalbi (INAF-IASFPA), M. Perri (ASDC), V. D'Elia (ASDC), A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), D.N. Burrows (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester) and S.B. Cenko report on behalf of the Swift-XRT team:
We have analysed 4.2 ks of XRT data for GRB 201027A (Cenko et al. GCN Circ. 28788), from 93 s to 52.6 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. 28792).
The light curve can be modelled with an initial power-law decay with an index of alpha=0.54 (+0.15, -0.21), followed by a break at T+1066 s to an alpha of 1.36 (+0.38, -0.21).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.81 (+0.23, -0.21). The best-fitting absorption column is 1.3 (+0.7, -0.6) x 10^21 cm^-2, in excess of the Galactic value of 4.7 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 3.8 x 10^-11 (4.6 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     1.3 (+0.7, -0.6) x 10^21 cm^-2
Galactic foreground: 4.7 x 10^20 cm^-2
Excess significance: 2.2 sigma
Photon index:	     1.81 (+0.23, -0.21)
```
If the light curve continues to decay with a power-law decay index of 1.36, the count rate at T+24 hours will be 1.0 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.9 x 10^-14 (4.7 x 10^-14) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01002158.
This circular is an official product of the Swift-XRT team.
GCN Circular #28799
A. A. Breeveld (UCL-MSSL) and S. B. Cenko (GSFC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 201027A 87 s after the BAT trigger (Cenko et al., GCN Circ. 28788). No optical afterglow consistent with the XRT position (Cenko et al. GCN Circ. 28788) is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC            87          236          147         >20.2
u_FC               299          548          246         >19.5
white               87         1721          411         >21.2
v                  629         1771          136         >18.3
b                  554         1696          117         >19.3
u                  299         1671          343         >20.1
w1                 678         1818          135         >19.1
m2                 653         1795           78         >20.4
w2                 604         1574          117         >20.2
```
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 #28801
H. A. Krimm (NSF), S. D. Barthelmy (GSFC), S. B. Cenko (GSFC), J. R. Cummings (CPI), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 201027A (trigger #1002158) (S. B. Cenko, et al., GCN Circ. 28788). The BAT ground-calculated position is RA, Dec = 155.954, -5.499 deg which is
```
   RA(J2000)  =  10h 23m 49.0s
   Dec(J2000) = -05d 29' 56.8"
```
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment). The partial coding was 44%.
The BAT light curve showed a complex structure with a duration of about 20 sec. T90 (15-350 keV) is 546.73 +- 420.95 sec (estimated error including systematics).
The time-averaged spectrum from T-3.86 to T+960 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.50 +- 0.00. The fluence in the 15-150 keV band is 0.0 +- 0.0 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T-0.29 sec in the 15-150 keV band is 1.4 +- 0.3 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/1002158/BA/
GCN Circular #28802
R. Hosokawa, H. Hara, R. Adachi, M. Niwano, F. Ogawa, K. L. Murata, N. Nakamura, N. Ito, S. Ogata, H. Takamatsu, Y. Yatsu, and N. Kawai (TokyoTech) report on behalf of the MITSuME collaboration:
We observed the field of GRB 201027A (V. Lipunov et al., GCN #28787, S. B. Cenko et al., GCN #28788, Y.-D. Hu et al., GCN #28794 ) 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 with a series of 60 sec exposures started at 2020-10-27 18:43:12 UT(17.2 hour after trigger). Since the first 18 images were taken under high airmass conditions, we stacked the images with good conditions. We did not find any new point sources within the enhanced Swift/XRT circle (J.P. Osborne et al., GCN #28792) in all three bands. We obtained the 5-sigma limits of the stacked images as follows.
```
T0+[hour] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
17.6 19:19:32 3180 g'>19.5,Rc>20.0,Ic>19.1
------------------------------------------------------------------------------------------------
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., https://doi.org/10.1093/pasj/psaa091, https://arxiv.org/abs/2008.11486; https://github.com/MNiwano/Eclaire).

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