Gamma-ray Burst 191228A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN/BACODINE POSITION NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Sat 28 Dec 19 00:02:48 UT
  NOTICE_TYPE:     Swift-BAT GRB Position
  TRIGGER_NUM:     946476,   Seg_Num: 0
  GRB_RA:            5.339d {+00h 21m 21s} (J2000),
                     5.594d {+00h 22m 22s} (current),
                     4.702d {+00h 18m 49s} (1950)
  GRB_DEC:          -8.670d {-08d 40' 12"} (J2000),
                    -8.560d {-08d 33' 33"} (current),
                    -8.948d {-08d 56' 50"} (1950)
  GRB_ERROR:       3.00 [arcmin radius, statistical only]
  GRB_INTEN:       0 [cnts]    Image_Peak=2655 [image_cnts]
  TRIGGER_DUR:     72.000 [sec] 
  TRIGGER_INDEX:   20000     E_range: 15-50 keV
  BKG_INTEN:       0 [cnts]
  BKG_TIME:        0.00 SOD {00:00:00.00} UT
  BKG_DUR:         0 [sec]
  GRB_DATE:        18845 TJD;   362 DOY;   19/12/28
  GRB_TIME:        79.83 SOD {00:01:19.83} UT
  GRB_PHI:          76.52 [deg]
  GRB_THETA:        11.30 [deg]
  SOLN_STATUS:     0x13
  RATE_SIGNIF:     0.00 [sigma]
  IMAGE_SIGNIF:    12.82 [sigma]
  MERIT_PARAMS:     +1  +0  +0  +6  +1  +2  +0  +0  -7  +0 
  SUN_POSTN:       276.47d {+18h 25m 52s}  -23.30d {-23d 18' 09"}
  SUN_DIST:         85.83 [deg]   Sun_angle= -5.9 [hr] (East of Sun)
  MOON_POSTN:      299.62d {+19h 58m 30s}  -22.49d {-22d 29' 19"}
  MOON_DIST:        64.60 [deg]
  MOON_ILLUM:      3 [%]
  GAL_COORDS:      100.46,-70.22 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:        1.42,-10.07 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        SWIFT-BAT GRB Coordinates.  
  COMMENTS:        This is an image trigger.  (The RATE_SIGNIF & BKG_{INTEN, TIME, DUR} are undefined.)  
  COMMENTS:        A point_source was found.  
  COMMENTS:        This does not match any source in the on-board catalog.  
  COMMENTS:        This does not match any source in the ground catalog.  
  COMMENTS:        This is a GRB.  
  COMMENTS:        This trigger occurred at longitude,latitude = 222.50,4.53 [deg].  
  

• red DSS finding chart ps-file
  
  
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Sat 28 Dec 19 00:03:46 UT
  NOTICE_TYPE:     Swift-XRT Position
  TRIGGER_NUM:     946476,   Seg_Num: 0
  GRB_RA:            5.3469d {+00h 21m 23.25s} (J2000),
                     5.6014d {+00h 22m 24.33s} (current),
                     4.7102d {+00h 18m 50.44s} (1950)
  GRB_DEC:          -8.6861d {-08d 41' 09.9"} (J2000),
                    -8.5753d {-08d 34' 31.1"} (current),
                    -8.9634d {-08d 57' 48.3"} (1950)
  GRB_ERROR:       6.4 [arcsec radius, statistical plus systematic, 90% containment]
  GRB_INTEN:       1.26e-08 [erg/cm2/sec]
  GRB_SIGNIF:      4.89 [sigma]
  IMG_START_DATE:  18845 TJD;   362 DOY;   19/12/28
  IMG_START_TIME:  203.24 SOD {00:03:23.24} UT,   123.4 [sec] since BAT Trigger Time
  TAM[0-3]:        327.68 237.18 261.73 243.57
  AMPLIFIER:       2
  WAVEFORM:        134
  SUN_POSTN:       276.47d {+18h 25m 53s}  -23.30d {-23d 18' 09"}
  SUN_DIST:         85.83 [deg]   Sun_angle= -5.9 [hr] (East of Sun)
  MOON_POSTN:      299.63d {+19h 58m 32s}  -22.49d {-22d 29' 15"}
  MOON_DIST:        64.59 [deg]
  MOON_ILLUM:      3 [%]
  GAL_COORDS:      100.46,-70.24 [deg] galactic lon,lat of the burst
  ECL_COORDS:        1.42,-10.09 [deg] ecliptic lon,lat of the burst
  COMMENTS:        SWIFT-XRT Coordinates.  
  COMMENTS:        The XRT position is 1.05 arcmin from the BAT position.  
  

• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Sat 28 Dec 19 00:03:57 UT
  NOTICE_TYPE:     Swift-XRT Processed Image
  TRIGGER_NUM:     946476,   Seg_Num: 0
  GRB_RA:            5.3469d {+00h 21m 23.2s} (J2000),
                     5.6014d {+00h 22m 24.3s} (current),
                     4.7102d {+00h 18m 50.4s} (1950)
  GRB_DEC:          -8.6861d {-08d 41' 09.9"} (J2000),
                    -8.5753d {-08d 34' 31.1"} (current),
                    -8.9634d {-08d 57' 48.3"} (1950)
  GRB_ERROR:       6.1 [arcsec, radius, statistical plus systematic]
  GRB_INTEN:       24 [cnts]
  IMG_START_DATE:  18845 TJD;   362 DOY;   19/12/28
  IMG_START_TIME:  203.24 SOD {00:03:23.24} UT,   123.4 [sec] since BAT Trigger Time
  CENTROID_X:      344.43,  raw= 344  [pixels]
  CENTROID_Y:      321.49,  raw= 321  [pixels]
  ROLL:            247.08 [deg]
  GAIN:            1
  MODE:            2, Short Image mode
  WAVEFORM:        134
  EXPO_TIME:       0.10 [sec]
  GRB_POS_XRT_Y:   55.14
  GRB_POS_XRT_Z:   87.30
  IMAGE_URL:       sw00946476000msxps_rw.img
  SUN_POSTN:       276.47d {+18h 25m 53s}  -23.30d {-23d 18' 09"}
  SUN_DIST:         85.83 [deg]   Sun_angle= -5.9 [hr] (East of Sun)
  MOON_POSTN:      299.63d {+19h 58m 32s}  -22.49d {-22d 29' 15"}
  MOON_DIST:        64.59 [deg]
  MOON_ILLUM:      3 [%]
  GAL_COORDS:      100.46,-70.24 [deg] galactic lon,lat of the burst
  ECL_COORDS:        1.42,-10.09 [deg] ecliptic lon,lat of the burst
  COMMENTS:        SWIFT-XRT Processed Image.  
  

  
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Sat 28 Dec 19 00:03:56 UT
  NOTICE_TYPE:     Swift-XRT Image
  TRIGGER_NUM:     946476,   Seg_Num: 0
  GRB_RA:            5.3469d {+00h 21m 23.2s} (J2000),
                     5.6014d {+00h 22m 24.3s} (current),
                     4.7102d {+00h 18m 50.4s} (1950)
  GRB_DEC:          -8.6861d {-08d 41' 09.9"} (J2000),
                    -8.5753d {-08d 34' 31.1"} (current),
                    -8.9634d {-08d 57' 48.3"} (1950)
  GRB_ERROR:       6.1 [arcsec, radius, statistical plus systematic]
  GRB_INTEN:       24 [cnts]
  IMG_START_DATE:  18845 TJD;   362 DOY;   19/12/28
  IMG_START_TIME:  203.24 SOD {00:03:23.24} UT,   123.4 [sec] since BAT Trigger Time
  CENTROID_X:      344.43,  raw= 344  [pixels]
  CENTROID_Y:      321.49,  raw= 321  [pixels]
  ROLL:            247.08 [deg]
  GAIN:            1
  MODE:            2, Short Image mode
  WAVEFORM:        134
  EXPO_TIME:       0.10 [sec]
  GRB_POS_XRT_Y:   55.14
  GRB_POS_XRT_Z:   87.30
  IMAGE_URL:       sw00946476000msxps_rw.img
  SUN_POSTN:       276.47d {+18h 25m 53s}  -23.30d {-23d 18' 09"}
  SUN_DIST:         85.83 [deg]   Sun_angle= -5.9 [hr] (East of Sun)
  MOON_POSTN:      299.63d {+19h 58m 32s}  -22.49d {-22d 29' 15"}
  MOON_DIST:        64.59 [deg]
  MOON_ILLUM:      3 [%]
  GAL_COORDS:      100.46,-70.24 [deg] galactic lon,lat of the burst
  ECL_COORDS:        1.42,-10.09 [deg] ecliptic lon,lat of the burst
  COMMENTS:        SWIFT-XRT Image.  
  

  
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Sat 28 Dec 19 00:05:37 UT
  NOTICE_TYPE:     Swift-BAT GRB Lightcurve
  TRIGGER_NUM:     946476,   Seg_Num: 0
  GRB_RA:            5.339d {+00h 21m 21s} (J2000),
                     5.594d {+00h 22m 22s} (current),
                     4.702d {+00h 18m 49s} (1950)
  GRB_DEC:          -8.670d {-08d 40' 12"} (J2000),
                    -8.560d {-08d 33' 33"} (current),
                    -8.948d {-08d 56' 50"} (1950)
  GRB_DATE:        18845 TJD;   362 DOY;   19/12/28
  GRB_TIME:        79.83 SOD {00:01:19.83} UT
  TRIGGER_INDEX:   20000
  GRB_PHI:          76.52 [deg]
  GRB_THETA:        11.30 [deg]
  DELTA_TIME:      0.00 [sec]
  TRIGGER_DUR:     72.000 [sec] 
  SOLN_STATUS:     0x13
  RATE_SIGNIF:     0.00 [sigma]
  IMAGE_SIGNIF:    12.82 [sigma]
  LC_URL:          sw00946476000msb.lc
  SUN_POSTN:       276.47d {+18h 25m 53s}  -23.30d {-23d 18' 09"}
  SUN_DIST:         85.83 [deg]   Sun_angle= -5.9 [hr] (East of Sun)
  MOON_POSTN:      299.65d {+19h 58m 36s}  -22.49d {-22d 29' 09"}
  MOON_DIST:        64.57 [deg]
  MOON_ILLUM:      3 [%]
  GAL_COORDS:      100.46,-70.22 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:        1.42,-10.07 [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 an image trigger.  
  COMMENTS:        A point_source was found.  
  COMMENTS:        This does not match any source in the on-board catalog.  
  COMMENTS:        This does not match any source in the ground catalog.  
  COMMENTS:        This is a GRB.  
  COMMENTS:        This trigger occurred at longitude,latitude = 222.50,4.53 [deg].  
  

  
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Sat 28 Dec 19 00:06:43 UT
  NOTICE_TYPE:     Swift-UVOT Source List
  TRIGGER_NUM:     946476,   Seg_Num: 0
  POINT_RA:          5.318d {+00h 21m 16s} (J2000)
  POINT_DEC:        -8.680d {-08d 40' 48"} (J2000)
  POINT_ROLL:      247.083d
  IMG_START_DATE:  18845 TJD;   362 DOY;   19/12/28
  IMG_START_TIME:  210.88 SOD {00:03:30.88} UT,   131.1 [sec] since BAT Trigger Time
  FILTER:          10, White
  BKG_MEAN:        4.113
  N_STARS:         70
  X_OFFSET:        328 [pixels]
  Y_OFFSET:        648 [pixels]
  X_MAX:           1287 [pixels]
  Y_MAX:           1607 [pixels]
  DET_THRESH:      17
  PHOTO_THRESH:    9
  SL_URL:          sw00946476000msufc0131.fits
  SUN_POSTN:       276.47d {+18h 25m 53s}  -23.30d {-23d 18' 09"}
  SUN_DIST:         85.80 [deg]   Sun_angle= -5.9 [hr] (East of Sun)
  MOON_POSTN:      299.66d {+19h 58m 39s}  -22.48d {-22d 29' 05"}
  MOON_DIST:        64.54 [deg]
  MOON_ILLUM:      3 [%]
  GAL_COORDS:      100.39,-70.22 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:        1.40,-10.07 [deg] ecliptic lon,lat of the pointing direction
  COMMENTS:        SWIFT-UVOT Source List.  
  

• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Sat 28 Dec 19 00:07:04 UT
  NOTICE_TYPE:     Swift-UVOT Processed Source List
  TRIGGER_NUM:     946476,   Seg_Num: 0
  POINT_RA:          5.318d {+00h 21m 16s} (J2000)
  POINT_DEC:        -8.680d {-08d 40' 48"} (J2000)
  POINT_ROLL:      247.083d
  IMG_START_DATE:  18845 TJD;   362 DOY;   19/12/28
  IMG_START_TIME:  210.88 SOD {00:03:30.88} UT,   131.1 [sec] since BAT Trigger Time
  FILTER:          10, White
  BKG_MEAN:        4.113
  N_STARS:         70
  X_OFFSET:        328 [pixels]
  Y_OFFSET:        648 [pixels]
  X_MAX:           1287 [pixels]
  Y_MAX:           1607 [pixels]
  DET_THRESH:      17
  PHOTO_THRESH:    9
  SL_URL:          sw00946476000msufc0131.fits
  SUN_POSTN:       276.47d {+18h 25m 53s}  -23.30d {-23d 18' 09"}
  SUN_DIST:         85.80 [deg]   Sun_angle= -5.9 [hr] (East of Sun)
  MOON_POSTN:      299.66d {+19h 58m 39s}  -22.48d {-22d 29' 04"}
  MOON_DIST:        64.54 [deg]
  MOON_ILLUM:      3 [%]
  GAL_COORDS:      100.39,-70.22 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:        1.40,-10.07 [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 28 Dec 19 00:08:14 UT
  NOTICE_TYPE:     Swift-UVOT Image
  TRIGGER_NUM:     946476,   Seg_Num: 0
  POINT_RA:          5.318d {+00h 21m 16s} (J2000)
  POINT_DEC:        -8.680d {-08d 40' 48"} (J2000)
  ROLL:            247.083d
  IMG_START_DATE:  18845 TJD;   362 DOY;   19/12/28
  IMG_START_TIME:  210.88 SOD {00:03:30.88} UT,   131.1 [sec] since BAT Trigger Time
  FILTER:          10, White
  EXPOSURE_ID:     599184235
  X_OFFSET:        589 [pixels]
  Y_OFFSET:        862 [pixels]
  WIDTH:           160 [pixels]
  HEIGHT:          160 [pixels]
  X_GRB_POS:       749
  Y_GRB_POS:       1022
  BINNING_INDEX:   1
  IM_URL:          sw00946476000msuni0156.fits
  SUN_POSTN:       276.47d {+18h 25m 53s}  -23.30d {-23d 18' 08"}
  SUN_DIST:         85.80 [deg]   Sun_angle= -5.9 [hr] (East of Sun)
  MOON_POSTN:      299.68d {+19h 58m 42s}  -22.48d {-22d 29' 00"}
  MOON_DIST:        64.53 [deg]
  MOON_ILLUM:      3 [%]
  GAL_COORDS:      100.39,-70.22 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:        1.40,-10.07 [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:     Sat 28 Dec 19 00:08:19 UT
  NOTICE_TYPE:     Swift-UVOT Processed Image
  TRIGGER_NUM:     946476,   Seg_Num: 0
  POINT_RA:          5.318d {+00h 21m 16s} (J2000)
  POINT_DEC:        -8.680d {-08d 40' 48"} (J2000)
  ROLL:            247.083d
  IMG_START_DATE:  18845 TJD;   362 DOY;   19/12/28
  IMG_START_TIME:  210.88 SOD {00:03:30.88} UT,   131.1 [sec] since BAT Trigger Time
  FILTER:          10, White
  EXPOSURE_ID:     599184235
  X_OFFSET:        589 [pixels]
  Y_OFFSET:        862 [pixels]
  WIDTH:           160 [pixels]
  HEIGHT:          160 [pixels]
  X_GRB_POS:       749
  Y_GRB_POS:       1022
  BINNING_INDEX:   1
  IM_URL:          sw00946476000msuni0156.fits
  SUN_POSTN:       276.47d {+18h 25m 53s}  -23.30d {-23d 18' 08"}
  SUN_DIST:         85.80 [deg]   Sun_angle= -5.9 [hr] (East of Sun)
  MOON_POSTN:      299.68d {+19h 58m 42s}  -22.48d {-22d 29' 00"}
  MOON_DIST:        64.53 [deg]
  MOON_ILLUM:      3 [%]
  GAL_COORDS:      100.39,-70.22 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:        1.40,-10.07 [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.  
  

  
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Sat 28 Dec 19 00:14:19 UT
  NOTICE_TYPE:     Swift-UVOT Source List
  TRIGGER_NUM:     946476,   Seg_Num: 0
  POINT_RA:          5.318d {+00h 21m 16s} (J2000)
  POINT_DEC:        -8.681d {-08d 40' 52"} (J2000)
  POINT_ROLL:      247.082d
  IMG_START_DATE:  18845 TJD;   362 DOY;   19/12/28
  IMG_START_TIME:  368.85 SOD {00:06:08.85} UT,   289.0 [sec] since BAT Trigger Time
  FILTER:          7, U
  BKG_MEAN:        0.985
  N_STARS:         99
  X_OFFSET:        269 [pixels]
  Y_OFFSET:        542 [pixels]
  X_MAX:           1228 [pixels]
  Y_MAX:           1501 [pixels]
  DET_THRESH:      9
  PHOTO_THRESH:    4
  SL_URL:          sw00946476000msufc0289.fits
  SUN_POSTN:       276.48d {+18h 25m 55s}  -23.30d {-23d 18' 08"}
  SUN_DIST:         85.80 [deg]   Sun_angle= -5.9 [hr] (East of Sun)
  MOON_POSTN:      299.73d {+19h 58m 56s}  -22.48d {-22d 28' 38"}
  MOON_DIST:        64.47 [deg]
  MOON_ILLUM:      3 [%]
  GAL_COORDS:      100.39,-70.22 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:        1.40,-10.07 [deg] ecliptic lon,lat of the pointing direction
  COMMENTS:        SWIFT-UVOT Source List.  
  

• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Sat 28 Dec 19 00:14:35 UT
  NOTICE_TYPE:     Swift-UVOT Processed Source List
  TRIGGER_NUM:     946476,   Seg_Num: 0
  POINT_RA:          5.318d {+00h 21m 16s} (J2000)
  POINT_DEC:        -8.681d {-08d 40' 52"} (J2000)
  POINT_ROLL:      247.082d
  IMG_START_DATE:  18845 TJD;   362 DOY;   19/12/28
  IMG_START_TIME:  368.85 SOD {00:06:08.85} UT,   289.0 [sec] since BAT Trigger Time
  FILTER:          7, U
  BKG_MEAN:        0.985
  N_STARS:         99
  X_OFFSET:        269 [pixels]
  Y_OFFSET:        542 [pixels]
  X_MAX:           1228 [pixels]
  Y_MAX:           1501 [pixels]
  DET_THRESH:      9
  PHOTO_THRESH:    4
  SL_URL:          sw00946476000msufc0289.fits
  SUN_POSTN:       276.48d {+18h 25m 55s}  -23.30d {-23d 18' 08"}
  SUN_DIST:         85.80 [deg]   Sun_angle= -5.9 [hr] (East of Sun)
  MOON_POSTN:      299.74d {+19h 58m 57s}  -22.48d {-22d 28' 37"}
  MOON_DIST:        64.47 [deg]
  MOON_ILLUM:      3 [%]
  GAL_COORDS:      100.39,-70.22 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:        1.40,-10.07 [deg] ecliptic lon,lat of the pointing direction
  COMMENTS:        SWIFT-UVOT Processed Source List.  
  COMMENTS:        If you have elected to receive attachments:  
  COMMENTS:        The uvot_catalog_srclist.fits.gz file does not exist; skipping the attachment.  
  

  
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Sat 28 Dec 19 00:15:41 UT
  NOTICE_TYPE:     Swift-UVOT Image
  TRIGGER_NUM:     946476,   Seg_Num: 0
  POINT_RA:          5.318d {+00h 21m 16s} (J2000)
  POINT_DEC:        -8.681d {-08d 40' 52"} (J2000)
  ROLL:            247.082d
  IMG_START_DATE:  18845 TJD;   362 DOY;   19/12/28
  IMG_START_TIME:  368.85 SOD {00:06:08.85} UT,   289.0 [sec] since BAT Trigger Time
  FILTER:          7, U
  EXPOSURE_ID:     599184393
  X_OFFSET:        589 [pixels]
  Y_OFFSET:        862 [pixels]
  WIDTH:           160 [pixels]
  HEIGHT:          160 [pixels]
  X_GRB_POS:       749
  Y_GRB_POS:       1022
  BINNING_INDEX:   1
  IM_URL:          sw00946476000msuni0314.fits
  SUN_POSTN:       276.48d {+18h 25m 55s}  -23.30d {-23d 18' 08"}
  SUN_DIST:         85.80 [deg]   Sun_angle= -5.9 [hr] (East of Sun)
  MOON_POSTN:      299.75d {+19h 58m 59s}  -22.48d {-22d 28' 33"}
  MOON_DIST:        64.46 [deg]
  MOON_ILLUM:      3 [%]
  GAL_COORDS:      100.39,-70.22 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:        1.40,-10.07 [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 Circular #26600
  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-IAC robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Spain (IAC Teide Observatory) was pointed to the Swift GRB191228.00 (trigger No 946476,00h 21m 21.36s , -08d 40m 12.0s, R=0.05) errorbox 146 sec after trigger time at 2019-12-28 00:03:46 UT, with upper limit up to 17.3 mag. The observations began at zenith distance = 82 deg. The sun altitude is -75.7 deg.
  The galactic latitude b = -70 deg., longitude l = 102 deg.
  Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1241866
  We obtain a following upper limits.

  Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
  _________|_____________________|_____|_______|______|________
  
       157 |          MASTER-IAC |  P| |    20 | 16.9 |        
       208 |          MASTER-IAC |  P| |    40 | 17.3 |        
       265 |          MASTER-IAC |  P| |    50 | 17.3 |        
  

  The observation and reduction will continue. The message may be cited.
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Sat 28 Dec 19 00:15:49 UT
  NOTICE_TYPE:     Swift-UVOT Processed Image
  TRIGGER_NUM:     946476,   Seg_Num: 0
  POINT_RA:          5.318d {+00h 21m 16s} (J2000)
  POINT_DEC:        -8.681d {-08d 40' 52"} (J2000)
  ROLL:            247.082d
  IMG_START_DATE:  18845 TJD;   362 DOY;   19/12/28
  IMG_START_TIME:  368.85 SOD {00:06:08.85} UT,   289.0 [sec] since BAT Trigger Time
  FILTER:          7, U
  EXPOSURE_ID:     599184393
  X_OFFSET:        589 [pixels]
  Y_OFFSET:        862 [pixels]
  WIDTH:           160 [pixels]
  HEIGHT:          160 [pixels]
  X_GRB_POS:       749
  Y_GRB_POS:       1022
  BINNING_INDEX:   1
  IM_URL:          sw00946476000msuni0314.fits
  SUN_POSTN:       276.48d {+18h 25m 55s}  -23.30d {-23d 18' 08"}
  SUN_DIST:         85.80 [deg]   Sun_angle= -5.9 [hr] (East of Sun)
  MOON_POSTN:      299.75d {+19h 58m 59s}  -22.48d {-22d 28' 32"}
  MOON_DIST:        64.46 [deg]
  MOON_ILLUM:      3 [%]
  GAL_COORDS:      100.39,-70.22 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:        1.40,-10.07 [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:        If you have elected to receive attachments:  
  COMMENTS:        The uvot_catalog_image.fits.gz file does not exist; skipping the attachment.  
  

  
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Sat 28 Dec 19 00:18:37 UT
  NOTICE_TYPE:     Swift-UVOT Source List
  TRIGGER_NUM:     946476,   Seg_Num: 0
  POINT_RA:          5.318d {+00h 21m 16s} (J2000)
  POINT_DEC:        -8.681d {-08d 40' 52"} (J2000)
  POINT_ROLL:      247.083d
  IMG_START_DATE:  18845 TJD;   362 DOY;   19/12/28
  IMG_START_TIME:  945.92 SOD {00:15:45.92} UT,   866.1 [sec] since BAT Trigger Time
  FILTER:          10, White
  BKG_MEAN:        3.273
  N_STARS:         178
  X_OFFSET:        29 [pixels]
  Y_OFFSET:        302 [pixels]
  X_MAX:           1468 [pixels]
  Y_MAX:           1741 [pixels]
  DET_THRESH:      15
  PHOTO_THRESH:    8
  SL_URL:          sw00946476000msufc0866.fits
  SUN_POSTN:       276.48d {+18h 25m 55s}  -23.30d {-23d 18' 07"}
  SUN_DIST:         85.79 [deg]   Sun_angle= -5.9 [hr] (East of Sun)
  MOON_POSTN:      299.77d {+19h 59m 06s}  -22.47d {-22d 28' 22"}
  MOON_DIST:        64.43 [deg]
  MOON_ILLUM:      3 [%]
  GAL_COORDS:      100.39,-70.22 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:        1.40,-10.07 [deg] ecliptic lon,lat of the pointing direction
  COMMENTS:        SWIFT-UVOT Source List.  
  

• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Sat 28 Dec 19 00:19:00 UT
  NOTICE_TYPE:     Swift-UVOT Processed Source List
  TRIGGER_NUM:     946476,   Seg_Num: 0
  POINT_RA:          5.318d {+00h 21m 16s} (J2000)
  POINT_DEC:        -8.681d {-08d 40' 52"} (J2000)
  POINT_ROLL:      247.083d
  IMG_START_DATE:  18845 TJD;   362 DOY;   19/12/28
  IMG_START_TIME:  945.92 SOD {00:15:45.92} UT,   866.1 [sec] since BAT Trigger Time
  FILTER:          10, White
  BKG_MEAN:        3.273
  N_STARS:         178
  X_OFFSET:        29 [pixels]
  Y_OFFSET:        302 [pixels]
  X_MAX:           1468 [pixels]
  Y_MAX:           1741 [pixels]
  DET_THRESH:      15
  PHOTO_THRESH:    8
  SL_URL:          sw00946476000msufc0866.fits
  SUN_POSTN:       276.48d {+18h 25m 55s}  -23.30d {-23d 18' 07"}
  SUN_DIST:         85.79 [deg]   Sun_angle= -5.9 [hr] (East of Sun)
  MOON_POSTN:      299.78d {+19h 59m 07s}  -22.47d {-22d 28' 21"}
  MOON_DIST:        64.43 [deg]
  MOON_ILLUM:      3 [%]
  GAL_COORDS:      100.39,-70.22 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:        1.40,-10.07 [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 28 Dec 19 00:19:05 UT
  NOTICE_TYPE:     Swift-XRT Position UPDATE
  TRIGGER_NUM:     946476,   Seg_Num: 0
  GRB_RA:            5.3467d {+00h 21m 23.20s} (J2000),
                     5.6012d {+00h 22m 24.28s} (current),
                     4.7100d {+00h 18m 50.39s} (1950)
  GRB_DEC:          -8.6826d {-08d 40' 57.3"} (J2000),
                    -8.5718d {-08d 34' 18.5"} (current),
                    -8.9599d {-08d 57' 35.7"} (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:  18845 TJD;   362 DOY;   19/12/28
  IMG_START_TIME:  425.00 SOD {00:07:05.00} UT,   345.2 [sec] since BAT Trigger Time
  TAM[0-3]:        100.00 100.00 100.00 100.00
  AMPLIFIER:       1
  WAVEFORM:        31
  SUN_POSTN:       276.48d {+18h 25m 55s}  -23.30d {-23d 18' 07"}
  SUN_DIST:         85.82 [deg]   Sun_angle= -5.9 [hr] (East of Sun)
  MOON_POSTN:      299.78d {+19h 59m 07s}  -22.47d {-22d 28' 21"}
  MOON_DIST:        64.46 [deg]
  MOON_ILLUM:      3 [%]
  GAL_COORDS:      100.46,-70.23 [deg] galactic lon,lat of the burst
  ECL_COORDS:        1.42,-10.09 [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 28 Dec 19 00:20:00 UT
  NOTICE_TYPE:     Swift-UVOT Image
  TRIGGER_NUM:     946476,   Seg_Num: 0
  POINT_RA:          5.318d {+00h 21m 16s} (J2000)
  POINT_DEC:        -8.681d {-08d 40' 52"} (J2000)
  ROLL:            247.083d
  IMG_START_DATE:  18845 TJD;   362 DOY;   19/12/28
  IMG_START_TIME:  945.92 SOD {00:15:45.92} UT,   866.1 [sec] since BAT Trigger Time
  FILTER:          10, White
  EXPOSURE_ID:     599184970
  X_OFFSET:        588 [pixels]
  Y_OFFSET:        861 [pixels]
  WIDTH:           160 [pixels]
  HEIGHT:          160 [pixels]
  X_GRB_POS:       748
  Y_GRB_POS:       1021
  BINNING_INDEX:   1
  IM_URL:          sw00946476000msuni0891.fits
  SUN_POSTN:       276.48d {+18h 25m 56s}  -23.30d {-23d 18' 07"}
  SUN_DIST:         85.79 [deg]   Sun_angle= -5.9 [hr] (East of Sun)
  MOON_POSTN:      299.79d {+19h 59m 09s}  -22.47d {-22d 28' 17"}
  MOON_DIST:        64.42 [deg]
  MOON_ILLUM:      3 [%]
  GAL_COORDS:      100.39,-70.22 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:        1.40,-10.07 [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 28 Dec 19 00:20:14 UT
  NOTICE_TYPE:     Swift-UVOT Processed Image
  TRIGGER_NUM:     946476,   Seg_Num: 0
  POINT_RA:          5.318d {+00h 21m 16s} (J2000)
  POINT_DEC:        -8.681d {-08d 40' 52"} (J2000)
  ROLL:            247.083d
  IMG_START_DATE:  18845 TJD;   362 DOY;   19/12/28
  IMG_START_TIME:  945.92 SOD {00:15:45.92} UT,   866.1 [sec] since BAT Trigger Time
  FILTER:          10, White
  EXPOSURE_ID:     599184970
  X_OFFSET:        588 [pixels]
  Y_OFFSET:        861 [pixels]
  WIDTH:           160 [pixels]
  HEIGHT:          160 [pixels]
  X_GRB_POS:       748
  Y_GRB_POS:       1021
  BINNING_INDEX:   1
  IM_URL:          sw00946476000msuni0891.fits
  SUN_POSTN:       276.48d {+18h 25m 56s}  -23.30d {-23d 18' 07"}
  SUN_DIST:         85.79 [deg]   Sun_angle= -5.9 [hr] (East of Sun)
  MOON_POSTN:      299.79d {+19h 59m 09s}  -22.47d {-22d 28' 16"}
  MOON_DIST:        64.42 [deg]
  MOON_ILLUM:      3 [%]
  GAL_COORDS:      100.39,-70.22 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:        1.40,-10.07 [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 #26601
  M. G. Bernardini (INAF-OAB), S. D. Barthelmy (GSFC), P. D'Avanzo (INAF-OAB), J.D. Gropp (PSU), J. A. Kennea (PSU), N. J. Klingler (PSU), S Laha (GSFC/UMBC/CRESST), A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), M. J. Moss (GWU) and A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift Observatory Team:
  At 00:01:19 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 191228A (trigger=946476). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 5.339, -8.670, which is

     RA(J2000)  =  00h 21m 21s
     Dec(J2000) = -08d 40' 12"
  

  with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve is typically plain for an image trigger.
  The XRT began observing the field at 00:03:23.2 UT, 123.4 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 5.34755, -8.68313 which is equivalent to:

     RA(J2000)  = 00h 21m 23.41s
     Dec(J2000) = -08d 40' 59.3"
  

  with an uncertainty of 3.7 arcseconds (radius, 90% containment). This location is 56 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. We cannot determine whether the source is fading at the present time.
  A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (3.80 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 4.4 (+5.17/-3.93) x 10^21 cm^-2 (90% confidence).
  The initial flux in the 0.1 s image was 1.26e-08 erg cm^-2 s^-1 (0.2-10 keV).
  UVOT took a finding chart exposure of 150 seconds with the White filter starting 131 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 M. G. Bernardini (grazia.bernardini AT brera.inaf.it). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/)
• GCN Circular #26603
  D. Xu, Z.P. Zhu, B.Y. Yu, H.J. Wang, L. Ge (NAOC) report:
  We observed the field of GRB 191228A (Bernardini et al., GCN 26601) using the 3.8-m United Kingdom Infra-Red Telescope (UKIRT). Observations started at 04:38:02 UT on 2019-12-28 (i.e., 4.612 hr after the BAT trigger), and 3600 s H-band imagining was obtained in a seeing of ~1.0".
  No NIR afterglow is detected in the stacked image at the XRT position (Bernardini et al., GCN 26601), down to a limiting magnitude of H ~ 20.1, calibrated with nearby 2MASS stars.
  We thank the great support of the UKIRT staff/observer, in particular Michael Pohlen and Watson Varricatt.
• GCN Circular #26604
  Tomas Mueller (Southampton), Juanita Antilen (Universidad de Chile), Daniele B. Malesani (DTU Space), Paolo D'Avanzo (INAF/Brera), Joe Anderson (ESO), Mariusz Gromadzki (Warsaw), Cosimo Inserra (Cardiff), Erkki Kankare (Turku), Matt Nicholl (Birmingham), Ofer Yaron (Weizmann), David Young (QUB), Roberta Carini (INAF/Roma), Regis Cartier (CTIO), Ting-Wan Chen (Stockholm), Matt Grayling, Mat Smith, Phil Wiseman (Southampton), Chris Frohmaier (ICG Portsmouth), report:
  We observed GRB 191228A (Bernardini et al., GCN 26601) under the the extended Public ESO Spectroscopic Survey for Transient Objects (ePESSTO+; see Smartt et al. 2015, A&A, 579, 40 http://www.pessto.org ). The observations were performed on the ESO New Technology Telescope at La Silla with the EFOSC2 instrument in imaging mode, starting on 2019 Dec 28 at 01:22:23 UT (i.e. 1.35 hr after the burst).
  In a 2-minute image taken using the r filter, we detect no objects consistent with the XRT position, down to a 3-sigma limiting magnitude of r = 22.6 AB (calibrated against stars from the Pan-STARRS catalog).
• GCN Circular #26606
  P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team.
  Using 2775 s of XRT Photon Counting mode data and 5 UVOT images for GRB 191228A, 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 = 5.34686, -8.68275 which is equivalent to:

  RA (J2000): 00h 21m 23.25s
  Dec (J2000): -08d 40' 57.9"
  

  with an uncertainty of 1.4 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 #26607
  T. N. Ukwatta (LANL) S. D. Barthelmy (GSFC), M. G. Bernardini (INAF-OAB), J. R. Cummings (CPI), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), (i.e. the Swift-BAT team):
  Using the data set from T-60 to T+243 sec from the recent telemetry downlinks, we report further analysis of BAT GRB 191228A (trigger #946476) (Bernardini, et al., GCN Circ. 26601). The BAT ground-calculated position is RA, Dec = 5.341, -8.650 deg, which is

     RA(J2000)  =  00h 21m 21.9s 
     Dec(J2000) = -08d 38' 58.3" 
  

  with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 90%.
  The mask-weighted light curve] shows 3 broad peaks starting at T-50 sec with peaks at ~T+5, ~T+55, and ~T+130 sec, and ending at T+190 sec. T90 (15-350 keV) is 166.9 +- 10.2 sec (estimated error including systematics).
  The time-averaged spectrum from T-39.2 to T+138.9 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.06 +- 0.14. The fluence in the 15-150 keV band is 2.0 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+54.59 sec in the 15-150 keV band is 0.6 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
  The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/946476/BA/
• GCN Circular #26609
  J. D. Gropp (PSU), A. Tohuvavohu (U. Toronto), J.A. Kennea (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-IASFPA) and M.G. Bernardini report on behalf of the Swift-XRT team:
  We have analysed 7.7 ks of XRT data for GRB 191228A (Bernardini et al. GCN Circ. 26601), from 127 s to 48.0 ks after the BAT trigger. The data comprise 216 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN Circ. 26606).
  The late-time light curve (from T0+5.4 ks) can be modelled with a power-law decay with a decay index of alpha=1.58 (+0.13, -0.12).
  A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.96 (+/-0.05). The best-fitting absorption column is 3.09 (+0.24, -0.23) x 10^21 cm^-2, in excess of the Galactic value of 3.8 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 2.14 (+0.16, -0.15) and a best-fitting absorption column of 4.0 (+/-0.7) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.6 x 10^-11 (6.1 x 10^-11) erg cm^-2 count^-1.
  A summary of the PC-mode spectrum is thus:

  Total column:	     4.0 (+/-0.7) x 10^21 cm^-2
  Galactic foreground: 3.8 x 10^20 cm^-2
  Excess significance: 8.7 sigma
  Photon index:	     2.14 (+0.16, -0.15)
  

  If the light curve continues to decay with a power-law decay index of 1.58, the count rate at T+24 hours will be 8.1 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.9 x 10^-13 (5.0 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/00946476.
  This circular is an official product of the Swift-XRT team.
• GCN Circular #26611
  GRB 191228A: Swift/UVOT Upper Limits
  J. D. Gropp (PSU) and M. G. Bernardini (INAF-OAB) report on behalf of the Swift/UVOT team:
  The Swift/UVOT began settled observations of the field of GRB 191228A 131 s after the BAT trigger (Bernardini et al., GCN Circ. 26601). No optical afterglow consistent with the XRT position (Bernardini et al. GCN Circ. 26601) 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           131          281          147         >20.3
  u_FC               289          539          246         >19.6
  white              131         1009          327         >20.6
  v                  619          811           39         >18.2
  b                  545          737           39         >19.2
  u                  289          712          265         >19.6
  w1                 668          860           39         >18.4
  

  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 #26615
  A. Pozanenko (IKI), E. Klunko (ISTP), N. Pankov (HSE), K. Kamyshnikov (HSE), E. Mazaeva (IKI), A. Volnova (IKI) report on behalf of IKI-GRB-FuN:
  We observed the field of GRB 191228A (Bernardini et al. GCN 26601) with AZT-33IK telescope of Sayan observatory (Mondy) starting on Dec. 28 (UT) 11:15:09. We do not detect any optical object in the Enhanced Swift-XRT position (Evans et al. GCN 26606). Preliminary photometry of the field is following.

  Date       UT start   t-T0       Filter Exp.    OT       UL(3sigma)
                         (mid, days)        (s)
  
  2019-12-28 11:15:09    0.48923    R     30*120  n/d      20.1
  

  Photometry is based on the USNO-B2.0 nearby stars.
• GCN Circular #26630
  R. Strausbaugh (U. of the Virgin Islands), A. Cucchiara (U. of the Virgin Islands/College of Marin) report on behalf of a larger collaboration:
  We observed Swift GRB 191228A (Barthelmy et al., GCN 26601) with the LCO 1-m Sinistro instrument at the McDonald Observatory, Texas, USA site, on December 28, from 00:59 to 01:31 UT (corresponding to 0.66 to 1.22 hours from the GRB trigger time) with Bessel R and I filters.
  We performed a series of 5x180s exposures in both bands. We do not detect any sources in the individual frames (nor in 5 stacked images in each band) in the enhanced Swift error region (Barthelmy et al., GCN 26607). Using the USNO-B.1 catalog as reference, we obtain the following 3-sigma upper limits:

  R > 14.69
  I > 14.79
  

  The low limiting magnitudes are most likely due to high sky background in the images in both bands.
• GCN Circular #26653
  Martin Jelinek (ASU CAS Ondrejov, CZ), Sergey Karpov, Martin Masek, Petr Janecek, Jakub Jurysek, Jan Ebr, Ronan Cunniffe, Petr Travnicek, Michael Prouza (Institute of Physics, Prague, CZ) and Jan Strobl (ASU CAS Ondrejov, CZ)
  report:
  The 25cm robotic telescope FRAM-CTA at La Palma (Spain) reacted robotically under inferior weather conditions to the alert of GRB 191228A (Bernardini et al., GCN Circular 26601) and obtained a set of 20s unfiltered images starting at 00:03:11.1 UT, i.e. 112s after the initial BAT trigger.
  We do not detect any new source in comparison to USNO-B1.0 catalog neither in single images nor in a combined 20x20s frame (mean exp time 363s post trigger, 3-sigma limit R>~17.7).