Gamma-ray Burst 191220A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 20 Dec 19 13:30:50 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     945344,   Seg_Num: 0
GRB_RA:          281.391d {+18h 45m 34s} (J2000),
                 281.592d {+18h 46m 22s} (current),
                 280.887d {+18h 43m 33s} (1950)
GRB_DEC:         +26.667d {+26d 40' 02"} (J2000),
                 +26.689d {+26d 41' 22"} (current),
                 +26.613d {+26d 36' 48"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       44331 [cnts]    Image_Peak=505 [image_cnts]
TRIGGER_DUR:     16.384 [sec] 
TRIGGER_INDEX:   460     E_range: 15-50 keV
BKG_INTEN:       164739 [cnts]
BKG_TIME:        48479.87 SOD {13:27:59.87} UT
BKG_DUR:         64 [sec]
GRB_DATE:        18837 TJD;   354 DOY;   19/12/20
GRB_TIME:        48577.79 SOD {13:29:37.79} UT
GRB_PHI:         -105.28 [deg]
GRB_THETA:        37.61 [deg]
SOLN_STATUS:     0x2003
RATE_SIGNIF:     8.88 [sigma]
IMAGE_SIGNIF:    7.80 [sigma]
MERIT_PARAMS:     +1  +0  +0  +4  +1  -2  +0  +0 -61  +0 
SUN_POSTN:       268.22d {+17h 52m 52s}  -23.43d {-23d 25' 32"}
SUN_DIST:         51.76 [deg]   Sun_angle= -0.9 [hr] (East of Sun)
MOON_POSTN:      196.94d {+13h 07m 45s}   -1.53d {-01d 31' 56"}
MOON_DIST:        85.92 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:       56.46, 13.00 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      285.76, 49.49 [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:        There is a bright star (mag=4.83) 6.87 arcmin from this position.  
COMMENTS:        This is a GRB.  
COMMENTS:        This trigger occurred at longitude,latitude = 13.81,20.10 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 20 Dec 19 13:32:25 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     945344,   Seg_Num: 0
GRB_RA:          281.3798d {+18h 45m 31.1s} (J2000),
                 281.5809d {+18h 46m 19.4s} (current),
                 280.8763d {+18h 43m 30.3s} (1950)
GRB_DEC:         +26.6577d {+26d 39' 27.7"} (J2000),
                 +26.6798d {+26d 40' 47.3"} (current),
                 +26.6040d {+26d 36' 14.2"} (1950)
GRB_ERROR:       6.5 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       21 [cnts]
IMG_START_DATE:  18837 TJD;   354 DOY;   19/12/20
IMG_START_TIME:  48710.23 SOD {13:31:50.23} UT,   132.4 [sec] since BAT Trigger Time
CENTROID_X:      246.49,  raw= 246  [pixels]
CENTROID_Y:      282.89,  raw= 283  [pixels]
ROLL:            195.44 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -35.84
GRB_POS_XRT_Z:   -143.57
IMAGE_URL:       sw00945344000msxps_rw.img
SUN_POSTN:       268.22d {+17h 52m 52s}  -23.43d {-23d 25' 32"}
SUN_DIST:         51.74 [deg]   Sun_angle= -0.9 [hr] (East of Sun)
MOON_POSTN:      196.95d {+13h 07m 49s}   -1.54d {-01d 32' 18"}
MOON_DIST:        85.90 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:       56.45, 13.01 [deg] galactic lon,lat of the burst
ECL_COORDS:      285.75, 49.48 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.  
COMMENTS:        There is a bright star (mag=4.83) 6.87 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 20 Dec 19 13:32:30 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     945344,   Seg_Num: 0
GRB_RA:          281.3798d {+18h 45m 31.1s} (J2000),
                 281.5809d {+18h 46m 19.4s} (current),
                 280.8763d {+18h 43m 30.3s} (1950)
GRB_DEC:         +26.6577d {+26d 39' 27.7"} (J2000),
                 +26.6798d {+26d 40' 47.3"} (current),
                 +26.6040d {+26d 36' 14.2"} (1950)
GRB_ERROR:       6.5 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       21 [cnts]
IMG_START_DATE:  18837 TJD;   354 DOY;   19/12/20
IMG_START_TIME:  48710.23 SOD {13:31:50.23} UT,   132.4 [sec] since BAT Trigger Time
CENTROID_X:      246.49,  raw= 246  [pixels]
CENTROID_Y:      282.89,  raw= 283  [pixels]
ROLL:            195.44 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -35.84
GRB_POS_XRT_Z:   -143.57
IMAGE_URL:       sw00945344000msxps_rw.img
SUN_POSTN:       268.22d {+17h 52m 52s}  -23.43d {-23d 25' 32"}
SUN_DIST:         51.74 [deg]   Sun_angle= -0.9 [hr] (East of Sun)
MOON_POSTN:      196.95d {+13h 07m 49s}   -1.54d {-01d 32' 19"}
MOON_DIST:        85.90 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:       56.45, 13.01 [deg] galactic lon,lat of the burst
ECL_COORDS:      285.75, 49.48 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.  
COMMENTS:        There is a bright star (mag=4.83) 6.87 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 20 Dec 19 13:32:16 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     945344,   Seg_Num: 0
GRB_RA:          281.3798d {+18h 45m 31.15s} (J2000),
                 281.5809d {+18h 46m 19.42s} (current),
                 280.8763d {+18h 43m 30.30s} (1950)
GRB_DEC:         +26.6577d {+26d 39' 27.7"} (J2000),
                 +26.6798d {+26d 40' 47.3"} (current),
                 +26.6040d {+26d 36' 14.2"} (1950)
GRB_ERROR:       6.8 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       4.03e-10 [erg/cm2/sec]
GRB_SIGNIF:      4.58 [sigma]
IMG_START_DATE:  18837 TJD;   354 DOY;   19/12/20
IMG_START_TIME:  48710.23 SOD {13:31:50.23} UT,   132.4 [sec] since BAT Trigger Time
TAM[0-3]:        327.67 237.19 261.61 243.52
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       268.22d {+17h 52m 52s}  -23.43d {-23d 25' 32"}
SUN_DIST:         51.74 [deg]   Sun_angle= -0.9 [hr] (East of Sun)
MOON_POSTN:      196.95d {+13h 07m 48s}   -1.54d {-01d 32' 16"}
MOON_DIST:        85.90 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:       56.45, 13.01 [deg] galactic lon,lat of the burst
ECL_COORDS:      285.75, 49.48 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 0.82 arcmin from the BAT position.  
COMMENTS:        There is a bright star (mag=4.83) 7.46 arcmin from the XRT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 20 Dec 19 13:33:41 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     945344,   Seg_Num: 0
GRB_RA:          281.391d {+18h 45m 34s} (J2000),
                 281.592d {+18h 46m 22s} (current),
                 280.887d {+18h 43m 33s} (1950)
GRB_DEC:         +26.667d {+26d 40' 02"} (J2000),
                 +26.689d {+26d 41' 22"} (current),
                 +26.613d {+26d 36' 48"} (1950)
GRB_DATE:        18837 TJD;   354 DOY;   19/12/20
GRB_TIME:        48577.79 SOD {13:29:37.79} UT
TRIGGER_INDEX:   460
GRB_PHI:         -105.28 [deg]
GRB_THETA:        37.61 [deg]
DELTA_TIME:      -31.00 [sec]
TRIGGER_DUR:     16.384 [sec] 
SOLN_STATUS:     0x2003
RATE_SIGNIF:     8.88 [sigma]
IMAGE_SIGNIF:    7.80 [sigma]
LC_URL:          sw00945344000msb.lc
SUN_POSTN:       268.22d {+17h 52m 52s}  -23.43d {-23d 25' 32"}
SUN_DIST:         51.76 [deg]   Sun_angle= -0.9 [hr] (East of Sun)
MOON_POSTN:      196.96d {+13h 07m 51s}   -1.54d {-01d 32' 36"}
MOON_DIST:        85.90 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:       56.46, 13.00 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      285.76, 49.49 [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:        There is a bright star (mag=4.83) 6.87 arcmin from this position.  
COMMENTS:        This is a GRB.  
COMMENTS:        This trigger occurred at longitude,latitude = 13.81,20.10 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 20 Dec 19 13:36:28 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     945344,   Seg_Num: 0
POINT_RA:        281.402d {+18h 45m 37s} (J2000)
POINT_DEC:       +26.693d {+26d 41' 36"} (J2000)
POINT_ROLL:      195.440d
IMG_START_DATE:  18837 TJD;   354 DOY;   19/12/20
IMG_START_TIME:  48715.51 SOD {13:31:55.51} UT,   137.7 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.968
N_STARS:         190
X_OFFSET:        440 [pixels]
Y_OFFSET:        216 [pixels]
X_MAX:           1879 [pixels]
Y_MAX:           1655 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    4
SL_URL:          sw00945344000msufc0137.fits
SUN_POSTN:       268.22d {+17h 52m 53s}  -23.43d {-23d 25' 33"}
SUN_DIST:         51.78 [deg]   Sun_angle= -0.9 [hr] (East of Sun)
MOON_POSTN:      196.99d {+13h 07m 57s}   -1.55d {-01d 33' 15"}
MOON_DIST:        85.89 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:       56.49, 13.01 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      285.78, 49.51 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.  
COMMENTS:        There is a bright star (mag=4.83) 6.87 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 20 Dec 19 13:36:42 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     945344,   Seg_Num: 0
POINT_RA:        281.402d {+18h 45m 37s} (J2000)
POINT_DEC:       +26.693d {+26d 41' 36"} (J2000)
POINT_ROLL:      195.440d
IMG_START_DATE:  18837 TJD;   354 DOY;   19/12/20
IMG_START_TIME:  48715.51 SOD {13:31:55.51} UT,   137.7 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.968
N_STARS:         190
X_OFFSET:        440 [pixels]
Y_OFFSET:        216 [pixels]
X_MAX:           1879 [pixels]
Y_MAX:           1655 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    4
SL_URL:          sw00945344000msufc0137.fits
SUN_POSTN:       268.22d {+17h 52m 53s}  -23.43d {-23d 25' 33"}
SUN_DIST:         51.78 [deg]   Sun_angle= -0.9 [hr] (East of Sun)
MOON_POSTN:      196.99d {+13h 07m 58s}   -1.56d {-01d 33' 18"}
MOON_DIST:        85.89 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:       56.49, 13.01 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      285.78, 49.51 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.  
COMMENTS:        There is a bright star (mag=4.83) 6.87 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 20 Dec 19 13:37:41 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     945344,   Seg_Num: 0
POINT_RA:        281.402d {+18h 45m 37s} (J2000)
POINT_DEC:       +26.693d {+26d 41' 36"} (J2000)
ROLL:            195.440d
IMG_START_DATE:  18837 TJD;   354 DOY;   19/12/20
IMG_START_TIME:  48715.51 SOD {13:31:55.51} UT,   137.7 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     598541539
X_OFFSET:        1097 [pixels]
Y_OFFSET:        779 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1257
Y_GRB_POS:       939
BINNING_INDEX:   1
IM_URL:          sw00945344000msuni0162.fits
SUN_POSTN:       268.22d {+17h 52m 53s}  -23.43d {-23d 25' 33"}
SUN_DIST:         51.78 [deg]   Sun_angle= -0.9 [hr] (East of Sun)
MOON_POSTN:      197.00d {+13h 08m 00s}   -1.56d {-01d 33' 31"}
MOON_DIST:        85.89 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:       56.49, 13.01 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      285.78, 49.51 [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).  
COMMENTS:        There is a bright star (mag=4.83) 6.87 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 20 Dec 19 13:37:52 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     945344,   Seg_Num: 0
POINT_RA:        281.402d {+18h 45m 37s} (J2000)
POINT_DEC:       +26.693d {+26d 41' 36"} (J2000)
ROLL:            195.440d
IMG_START_DATE:  18837 TJD;   354 DOY;   19/12/20
IMG_START_TIME:  48715.51 SOD {13:31:55.51} UT,   137.7 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     598541539
X_OFFSET:        1097 [pixels]
Y_OFFSET:        779 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1257
Y_GRB_POS:       939
BINNING_INDEX:   1
IM_URL:          sw00945344000msuni0162.fits
SUN_POSTN:       268.22d {+17h 52m 53s}  -23.43d {-23d 25' 33"}
SUN_DIST:         51.78 [deg]   Sun_angle= -0.9 [hr] (East of Sun)
MOON_POSTN:      197.00d {+13h 08m 00s}   -1.56d {-01d 33' 34"}
MOON_DIST:        85.88 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:       56.49, 13.01 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      285.78, 49.51 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.  
COMMENTS:        There is a bright star (mag=4.83) 6.87 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 20 Dec 19 13:49:01 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     945344,   Seg_Num: 0
POINT_RA:        281.401d {+18h 45m 36s} (J2000)
POINT_DEC:       +26.697d {+26d 41' 48"} (J2000)
POINT_ROLL:      195.440d
IMG_START_DATE:  18837 TJD;   354 DOY;   19/12/20
IMG_START_TIME:  49450.69 SOD {13:44:10.69} UT,   872.9 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.687
N_STARS:         190
X_OFFSET:        537 [pixels]
Y_OFFSET:        219 [pixels]
X_MAX:           1976 [pixels]
Y_MAX:           1658 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw00945344000msufc0872.fits
SUN_POSTN:       268.23d {+17h 52m 55s}  -23.43d {-23d 25' 33"}
SUN_DIST:         51.78 [deg]   Sun_angle= -0.9 [hr] (East of Sun)
MOON_POSTN:      197.10d {+13h 08m 24s}   -1.60d {-01d 36' 09"}
MOON_DIST:        85.81 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:       56.49, 13.01 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      285.78, 49.51 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.  
COMMENTS:        There is a bright star (mag=4.83) 6.87 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 20 Dec 19 13:49:19 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     945344,   Seg_Num: 0
POINT_RA:        281.401d {+18h 45m 36s} (J2000)
POINT_DEC:       +26.697d {+26d 41' 48"} (J2000)
POINT_ROLL:      195.440d
IMG_START_DATE:  18837 TJD;   354 DOY;   19/12/20
IMG_START_TIME:  49450.69 SOD {13:44:10.69} UT,   872.9 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.687
N_STARS:         190
X_OFFSET:        537 [pixels]
Y_OFFSET:        219 [pixels]
X_MAX:           1976 [pixels]
Y_MAX:           1658 [pixels]
DET_THRESH:      7
PHOTO_THRESH:    3
SL_URL:          sw00945344000msufc0872.fits
SUN_POSTN:       268.23d {+17h 52m 55s}  -23.43d {-23d 25' 33"}
SUN_DIST:         51.78 [deg]   Sun_angle= -0.9 [hr] (East of Sun)
MOON_POSTN:      197.10d {+13h 08m 25s}   -1.60d {-01d 36' 13"}
MOON_DIST:        85.81 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:       56.49, 13.01 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      285.78, 49.51 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.  
COMMENTS:        There is a bright star (mag=4.83) 6.87 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 20 Dec 19 13:50:25 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     945344,   Seg_Num: 0
POINT_RA:        281.401d {+18h 45m 36s} (J2000)
POINT_DEC:       +26.697d {+26d 41' 48"} (J2000)
ROLL:            195.440d
IMG_START_DATE:  18837 TJD;   354 DOY;   19/12/20
IMG_START_TIME:  49450.69 SOD {13:44:10.69} UT,   872.9 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     598542274
X_OFFSET:        1096 [pixels]
Y_OFFSET:        778 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1256
Y_GRB_POS:       938
BINNING_INDEX:   1
IM_URL:          sw00945344000msuni0897.fits
SUN_POSTN:       268.23d {+17h 52m 55s}  -23.43d {-23d 25' 33"}
SUN_DIST:         51.78 [deg]   Sun_angle= -0.9 [hr] (East of Sun)
MOON_POSTN:      197.11d {+13h 08m 28s}   -1.61d {-01d 36' 29"}
MOON_DIST:        85.81 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:       56.49, 13.01 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      285.78, 49.51 [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).  
COMMENTS:        There is a bright star (mag=4.83) 6.87 arcmin from the BAT position.

GCN Circular #26514
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),
H.Levato (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE),
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-Tunka robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Applied Physics Institute, Irkutsk State University) was pointed to the Swift GRB191220.56 (trigger No 945344,18h 45m 33.79s , +26d 40m 01.9s, R=0.05) errorbox 13 sec after notice time and 90 sec after trigger time at 2019-12-20 13:31:08 UT, with upper limit up to 16.0 mag. The observations began at zenith distance = 82 deg. The sun altitude is -40.9 deg.
The galactic latitude b = 13 deg., longitude l = 57 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1233370
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

     101 |        MASTER-Tunka |  P| |    20 | 14.9 |        
     140 |        MASTER-Tunka |  P| |    20 | 15.0 |        
     185 |        MASTER-Tunka |  P| |    30 | 15.5 |        
     239 |        MASTER-Tunka |  P| |    40 | 15.4 |        
     304 |        MASTER-Tunka |  P| |    50 | 15.8 |        
     383 |        MASTER-Tunka |  P| |    70 | 15.9 |        
     477 |        MASTER-Tunka |  P| |    80 | 16.0 |        
```
The observation and reduction will continue. The message may be cited.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 20 Dec 19 13:49:38 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     945344,   Seg_Num: 0
GRB_RA:          281.3799d {+18h 45m 31.17s} (J2000),
                 281.5810d {+18h 46m 19.44s} (current),
                 280.8763d {+18h 43m 30.32s} (1950)
GRB_DEC:         +26.6557d {+26d 39' 20.5"} (J2000),
                 +26.6778d {+26d 40' 40.1"} (current),
                 +26.6020d {+26d 36' 07.0"} (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:  18837 TJD;   354 DOY;   19/12/20
IMG_START_TIME:  48756.00 SOD {13:32:36.00} UT,   178.2 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       268.23d {+17h 52m 55s}  -23.43d {-23d 25' 33"}
SUN_DIST:         51.74 [deg]   Sun_angle= -0.9 [hr] (East of Sun)
MOON_POSTN:      197.11d {+13h 08m 26s}   -1.61d {-01d 36' 18"}
MOON_DIST:        85.79 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:       56.45, 13.01 [deg] galactic lon,lat of the burst
ECL_COORDS:      285.75, 49.47 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        There is a bright star (mag=4.83) 7.46 arcmin from the XRT position.  
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:     Fri 20 Dec 19 13:50:41 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     945344,   Seg_Num: 0
POINT_RA:        281.401d {+18h 45m 36s} (J2000)
POINT_DEC:       +26.697d {+26d 41' 48"} (J2000)
ROLL:            195.440d
IMG_START_DATE:  18837 TJD;   354 DOY;   19/12/20
IMG_START_TIME:  49450.69 SOD {13:44:10.69} UT,   872.9 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     598542274
X_OFFSET:        1096 [pixels]
Y_OFFSET:        778 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1256
Y_GRB_POS:       938
BINNING_INDEX:   1
IM_URL:          sw00945344000msuni0897.fits
SUN_POSTN:       268.23d {+17h 52m 55s}  -23.43d {-23d 25' 33"}
SUN_DIST:         51.78 [deg]   Sun_angle= -0.9 [hr] (East of Sun)
MOON_POSTN:      197.12d {+13h 08m 28s}   -1.61d {-01d 36' 32"}
MOON_DIST:        85.80 [deg]
MOON_ILLUM:      35 [%]
GAL_COORDS:       56.49, 13.01 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      285.78, 49.51 [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.  
COMMENTS:        There is a bright star (mag=4.83) 6.87 arcmin from the BAT position.

GCN Circular #26515
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Using promptly downlinked XRT event data for GRB 191220A, we find an enhanced XRT position of the afterglow: RA, Dec: 281.3800, 26.6558 which is equivalent to:
```
   RA (J2000)  = 18 45 31.19
   Dec (J2000) = +26 39 20.9
```
with an uncertainty of 2.3 arcseconds (radius, 90% confidence). Analysis of the promptly available data is online at http://www.swift.ac.uk/sper/945344.
Position enhancement is is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177).
This circular is an official product of the Swift-XRT team.
GCN Circular #26516
S. Laha (GSFC/UMBC/CRESST), D. N. Burrows (PSU), J.D. Gropp (PSU), N. P. M. Kuin (UCL-MSSL), A. Y. Lien (GSFC/UMBC), K. L. Page (U Leicester), D. M. Palmer (LANL) and A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift Observatory Team:
At 13:29:37 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 191220A (trigger=945344). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 281.391, +26.667 which is
```
   RA(J2000) = 18h 45m 34s
   Dec(J2000) = +26d 40' 02"
```
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 ~200 counts/sec (15-350 keV), at ~1 sec after the trigger.
The XRT began observing the field at 13:31:50.2 UT, 132.4 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source located at RA, Dec 281.37924, 26.65599 which is equivalent to:
```
   RA(J2000)  = 18h 45m 31.02s
   Dec(J2000) = +26d 39' 21.6"
```
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This location is 54 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 1.53 x 10^21 cm^-2 (Willingale et al. 2013).
The initial flux in the 2.5 s image was 4.03e-10 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 250 seconds with the U filter starting 137 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 19.2 mag. The 8'x8' region for the list of sources generated on-board covers 0.00% of the XRT error circle. No correction has been made for the expected extinction corresponding to E(B-V) of 0.14.
Burst Advocate for this burst is S Laha (sib.laha AT gmail.com). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/)
GCN Circular #26519
A. Moskvitin on behalf of larger GRB follow-up team report.
We observed the field of the GRB 191220A with the SAO RAS Zeiss-1000 telescope equipped with the MMPP (Multi-Mode Photometer-Polarimeter). The observations were started since 1.419 hours after the trigger (Laha et al., GCNC #26516). We obtained 8 x 300 sec. frames in Rc band (14:54:44 -- 15:39:44 UT).
Within the enhanced XRT error circle (Evans, GCNC #26515) we detect single object, possible OT, with the coordinates R. A. = 18:45:31.10, Decl. = +26:39:20.8, +/- 0".3, Epoch = 2000. ftp://ftp.sao.ru/pub/grb/GRB191220A/GRB_possibleOT.jpg
Preliminary brightness of the object is R = 20.46 +/- 0.08 (T_mid - T0 = 1.794 h). Photometry were made against the R2 magnitudes of nearby USNO-B1 stars.
GCN Circular #26522
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team.
Using 2496 s of XRT Photon Counting mode data and 10 UVOT images for GRB 191220A, 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 = 281.37980, +26.65588 which is equivalent to:
```
RA (J2000): 18h 45m 31.15s
Dec (J2000): +26d 39' 21.2"
```
with an uncertainty of 2.3 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 #26524
A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), B. Sbarufatti (PSU), D.N. Burrows (PSU), J. D. Gropp (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), M.G. Bernardini (INAF-OAB) and S. Laha report on behalf of the Swift-XRT team:
We have analysed 8.0 ks of XRT data for GRB 191220A (Laha et al. GCN Circ. 26516), from 138 s to 23.9 ks after the BAT trigger. The data comprise 38 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN Circ. 26515).
The light curve can be modelled with an initial power-law decay with an index of alpha=4.2 (+0.7, -1.5), followed by a break at T+349 s to an alpha of 0.51 (+0.14, -0.30).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.01 (+0.18, -0.14). The best-fitting absorption column is consistent with the Galactic value of 1.5 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.4 x 10^-11 (4.1 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     1.53 (+/-0.25) x 10^21 cm^-2
Galactic foreground: 1.5 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:	     2.01 (+0.18, -0.14)
```
If the light curve continues to decay with a power-law decay index of 0.51, the count rate at T+24 hours will be 9.8 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.3 x 10^-13 (4.0 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/00945344.
This circular is an official product of the Swift-XRT team.
GCN Circular #26525
S. Belkin (IKI), A. Pozanenko (IKI), R. Ya. Inasaridze (AbAO), V.R. Ayvazian (AbAO), G. V. Kapanadze (AbAO), E. Mazaeva (IKI), A. Volnova (IKI), I. Molotov (KIAM) report on behalf of GRB IKI FuN:
We observed the field of GRB 191220A (Evans et al., GCN 26515; Laha et al., GCN 26516) with AS-32 (0.7m) telescope of Abastumani Observatory starting on Dec. 20 (UT) 14:40:39. We do no detect any source within enhanced Swift-XRT position (Osborne et al., GCN 26522). In particular we do not detect the candidate in the OT (Moskvitin, GCN 26519). Preliminary photometry of the field is following.
```
Date       UT start  t-T0    Filter Exp.  OT    Err. UL
                     (mid, days)     (s)
2019-12-20 14:40:39  0.05037 R      23*60 n/d   n/d  19.8
```
The photometry is based on nearby USNO-B1.0 stars
```
UUSNO-B1.0_id R2
1166-0338499  14.74
1166-0338587  15.40
1166-0338614  15.08
```
GCN Circular #26526
N. P. M. Kuin (UCL-MSSL) and S. L. Laha (GSFC/UMBC/CRESST) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 191220A 138 s after the BAT trigger (Laha et al., GCN Circ. 26516). No optical afterglow consistent with the XRT position (Laha et al. GCN Circ. 26516) 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

u_FC               138          387          246         >19.8
u                  138         6726         1061         >20.0
w1                 446         6521          687         >19.6
m2                 420         6316          687         >19.9
w2                 396         6766          719         >21.1
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.14 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #26535
D. M. Palmer (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), T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (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 191220A (trigger #945344) (Laha et al., GCN Circ. 26516). The BAT ground-calculated position is RA, Dec = 281.335, 26.679 deg which is
```
   RA(J2000)  =  18h 45m 20.3s
   Dec(J2000) = +26d 40' 43.1"
```
with an uncertainty of 3.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 19%.
The mask weighted light curve shows complex structures with a duration of ~50 sec, with a hint of some weak emission lasting till ~ T+ 240 s. The overall structure starts at ~ T-2 sec and lasts till ~ T+60 sec. T90 (15-350 keV) is 175.55 +- 125.93 sec (estimated error including systematics).
The time-averaged spectrum from T-2.46 to T+248.42 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.12 +- 0.40. The fluence in the 15-150 keV band is 1.1 +- 0.3 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+6.69 sec in the 15-150 keV band is 1.1 +- 0.4 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/945344/BA/

Back to JG's homepage

Jochen Greiner, last update: 21-Dec-2019 [Disclaimer]