Gamma-ray Burst 200224A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN/BACODINE POSITION NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Mon 24 Feb 20 03:25:47 UT
  NOTICE_TYPE:     Swift-BAT GRB Position
  TRIGGER_NUM:     958141,   Seg_Num: 0
  GRB_RA:          248.794d {+16h 35m 11s} (J2000),
                   248.959d {+16h 35m 50s} (current),
                   248.385d {+16h 33m 32s} (1950)
  GRB_DEC:         +41.675d {+41d 40' 31"} (J2000),
                   +41.635d {+41d 38' 05"} (current),
                   +41.777d {+41d 46' 37"} (1950)
  GRB_ERROR:       3.00 [arcmin radius, statistical only]
  GRB_INTEN:       11878 [cnts]    Image_Peak=291 [image_cnts]
  TRIGGER_DUR:     4.096 [sec] 
  TRIGGER_INDEX:   475     E_range: 25-100 keV
  BKG_INTEN:       105869 [cnts]
  BKG_TIME:        12231.51 SOD {03:23:51.51} UT
  BKG_DUR:         40 [sec]
  GRB_DATE:        18903 TJD;    55 DOY;   20/02/24
  GRB_TIME:        12289.30 SOD {03:24:49.30} UT
  GRB_PHI:         156.50 [deg]
  GRB_THETA:         6.91 [deg]
  SOLN_STATUS:     0x83
  RATE_SIGNIF:     10.72 [sigma]
  IMAGE_SIGNIF:    6.80 [sigma]
  MERIT_PARAMS:     +1  +0  +0  +2  +2  -3  +0  +0  +8  +0 
  SUN_POSTN:       336.82d {+22h 27m 16s}   -9.68d {-09d 41' 03"}
  SUN_DIST:         94.83 [deg]   Sun_angle= 5.9 [hr] (West of Sun)
  MOON_POSTN:      343.59d {+22h 54m 23s}  -11.91d {-11d 54' 33"}
  MOON_DIST:       101.31 [deg]
  MOON_ILLUM:      0 [%]
  GAL_COORDS:       65.88, 42.50 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      234.18, 62.50 [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:        Since the IMAGE_SIGNIF is less than 7 sigma, this is a questionable detection.  
  COMMENTS:        This trigger occurred at longitude,latitude = 349.94,20.64 [deg].  
  

• red DSS finding chart ps-file
  
  
• GCN NOTICE
  

   
  TITLE:           GCN/SWIFT NOTICE 
  NOTICE_DATE:     Mon 24 Feb 20 03:26:42 UT 
  NOTICE_TYPE:     Swift-XRT Nack-Position 
  TRIGGER_NUM:     958141,   Seg_Num: 0 
  POINT_RA:        248.804d {+16h 35m 13s} (J2000) 
  POINT_DEC:       +41.676d {+41d 40' 32"} (J2000) 
  IMG_START_DATE:  18903 TJD;    55 DOY;   20/02/24 
  IMG_START_TIME:  12386.98 SOD {03:26:26.98} UT,   97.7 [sec] since BAT Trigger Time 
  COUNTS:          2    Min_needed= 20 
  STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec] 
  PH2_ITER:        1    Max_iter_allowed= 4 
  ERROR_CODE:      1 
  COMMENTS:        SWIFT-XRT Nack Position.   
  COMMENTS:        No source found in the image.   
  

• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Mon 24 Feb 20 03:28:40 UT
  NOTICE_TYPE:     Swift-BAT GRB Lightcurve
  TRIGGER_NUM:     958141,   Seg_Num: 0
  GRB_RA:          248.794d {+16h 35m 11s} (J2000),
                   248.959d {+16h 35m 50s} (current),
                   248.385d {+16h 33m 32s} (1950)
  GRB_DEC:         +41.675d {+41d 40' 31"} (J2000),
                   +41.635d {+41d 38' 05"} (current),
                   +41.777d {+41d 46' 37"} (1950)
  GRB_DATE:        18903 TJD;    55 DOY;   20/02/24
  GRB_TIME:        12289.30 SOD {03:24:49.30} UT
  TRIGGER_INDEX:   475
  GRB_PHI:         156.50 [deg]
  GRB_THETA:         6.91 [deg]
  DELTA_TIME:      -18.00 [sec]
  TRIGGER_DUR:     4.096 [sec] 
  SOLN_STATUS:     0x83
  RATE_SIGNIF:     10.72 [sigma]
  IMAGE_SIGNIF:    6.80 [sigma]
  LC_URL:          sw00958141000msb.lc
  SUN_POSTN:       336.82d {+22h 27m 16s}   -9.68d {-09d 41' 00"}
  SUN_DIST:         94.83 [deg]   Sun_angle= 5.9 [hr] (West of Sun)
  MOON_POSTN:      343.62d {+22h 54m 28s}  -11.90d {-11d 54' 03"}
  MOON_DIST:       101.33 [deg]
  MOON_ILLUM:      0 [%]
  GAL_COORDS:       65.88, 42.50 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      234.18, 62.50 [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:        Since the IMAGE_SIGNIF is less than 7 sigma, this is a questionable detection.  
  COMMENTS:        This trigger occurred at longitude,latitude = 349.94,20.64 [deg].  
  

  
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Mon 24 Feb 20 03:29:28 UT
  NOTICE_TYPE:     Swift-UVOT Source List
  TRIGGER_NUM:     958141,   Seg_Num: 0
  POINT_RA:        248.803d {+16h 35m 13s} (J2000)
  POINT_DEC:       +41.675d {+41d 40' 32"} (J2000)
  POINT_ROLL:      98.571d
  IMG_START_DATE:  18903 TJD;    55 DOY;   20/02/24
  IMG_START_TIME:  12390.31 SOD {03:26:30.31} UT,   101.0 [sec] since BAT Trigger Time
  FILTER:          10, White
  BKG_MEAN:        1.364
  N_STARS:         37
  X_OFFSET:        426 [pixels]
  Y_OFFSET:        578 [pixels]
  X_MAX:           1385 [pixels]
  Y_MAX:           1537 [pixels]
  DET_THRESH:      10
  PHOTO_THRESH:    5
  SL_URL:          sw00958141000msufc0101.fits
  SUN_POSTN:       336.82d {+22h 27m 16s}   -9.68d {-09d 41' 00"}
  SUN_DIST:         94.82 [deg]   Sun_angle= 5.9 [hr] (West of Sun)
  MOON_POSTN:      343.62d {+22h 54m 30s}  -11.90d {-11d 53' 55"}
  MOON_DIST:       101.32 [deg]
  MOON_ILLUM:      0 [%]
  GAL_COORDS:       65.88, 42.49 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:      234.20, 62.51 [deg] ecliptic lon,lat of the pointing direction
  COMMENTS:        SWIFT-UVOT Source List.  
  

• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Mon 24 Feb 20 03:29:39 UT
  NOTICE_TYPE:     Swift-UVOT Processed Source List
  TRIGGER_NUM:     958141,   Seg_Num: 0
  POINT_RA:        248.803d {+16h 35m 13s} (J2000)
  POINT_DEC:       +41.675d {+41d 40' 32"} (J2000)
  POINT_ROLL:      98.571d
  IMG_START_DATE:  18903 TJD;    55 DOY;   20/02/24
  IMG_START_TIME:  12390.31 SOD {03:26:30.31} UT,   101.0 [sec] since BAT Trigger Time
  FILTER:          10, White
  BKG_MEAN:        1.364
  N_STARS:         37
  X_OFFSET:        426 [pixels]
  Y_OFFSET:        578 [pixels]
  X_MAX:           1385 [pixels]
  Y_MAX:           1537 [pixels]
  DET_THRESH:      10
  PHOTO_THRESH:    5
  SL_URL:          sw00958141000msufc0101.fits
  SUN_POSTN:       336.82d {+22h 27m 16s}   -9.68d {-09d 41' 00"}
  SUN_DIST:         94.82 [deg]   Sun_angle= 5.9 [hr] (West of Sun)
  MOON_POSTN:      343.62d {+22h 54m 30s}  -11.90d {-11d 53' 53"}
  MOON_DIST:       101.32 [deg]
  MOON_ILLUM:      0 [%]
  GAL_COORDS:       65.88, 42.49 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:      234.20, 62.51 [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:     Mon 24 Feb 20 03:30:42 UT
  NOTICE_TYPE:     Swift-XRT Position
  TRIGGER_NUM:     958141,   Seg_Num: 0
  GRB_RA:          248.7658d {+16h 35m 03.79s} (J2000),
                   248.9311d {+16h 35m 43.46s} (current),
                   248.3559d {+16h 33m 25.40s} (1950)
  GRB_DEC:         +41.6125d {+41d 36' 44.9"} (J2000),
                   +41.5720d {+41d 34' 19.2"} (current),
                   +41.7143d {+41d 42' 51.3"} (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:  18903 TJD;    55 DOY;   20/02/24
  IMG_START_TIME:  12394.00 SOD {03:26:34.00} UT,   104.7 [sec] since BAT Trigger Time
  TAM[0-3]:        100.00 100.00 100.00 100.00
  AMPLIFIER:       1
  WAVEFORM:        31
  SUN_POSTN:       336.82d {+22h 27m 17s}   -9.68d {-09d 40' 58"}
  SUN_DIST:         94.84 [deg]   Sun_angle= 5.9 [hr] (West of Sun)
  MOON_POSTN:      343.63d {+22h 54m 32s}  -11.90d {-11d 53' 42"}
  MOON_DIST:       101.35 [deg]
  MOON_ILLUM:      0 [%]
  GAL_COORDS:       65.79, 42.52 [deg] galactic lon,lat of the burst
  ECL_COORDS:      234.18, 62.44 [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 0.58% < P(seren) < 1.1%.  
  

• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Mon 24 Feb 20 03:30:52 UT
  NOTICE_TYPE:     Swift-UVOT Image
  TRIGGER_NUM:     958141,   Seg_Num: 0
  POINT_RA:        248.803d {+16h 35m 13s} (J2000)
  POINT_DEC:       +41.675d {+41d 40' 32"} (J2000)
  ROLL:            98.571d
  IMG_START_DATE:  18903 TJD;    55 DOY;   20/02/24
  IMG_START_TIME:  12390.31 SOD {03:26:30.31} UT,   101.0 [sec] since BAT Trigger Time
  FILTER:          10, White
  EXPOSURE_ID:     604207614
  X_OFFSET:        745 [pixels]
  Y_OFFSET:        897 [pixels]
  WIDTH:           160 [pixels]
  HEIGHT:          160 [pixels]
  X_GRB_POS:       905
  Y_GRB_POS:       1057
  BINNING_INDEX:   1
  IM_URL:          sw00958141000msuni0126.fits
  SUN_POSTN:       336.82d {+22h 27m 17s}   -9.68d {-09d 40' 58"}
  SUN_DIST:         94.83 [deg]   Sun_angle= 5.9 [hr] (West of Sun)
  MOON_POSTN:      343.63d {+22h 54m 32s}  -11.89d {-11d 53' 40"}
  MOON_DIST:       101.33 [deg]
  MOON_ILLUM:      0 [%]
  GAL_COORDS:       65.88, 42.49 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:      234.20, 62.51 [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).  
  

• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Mon 24 Feb 20 03:37:14 UT
  NOTICE_TYPE:     Swift-UVOT Source List
  TRIGGER_NUM:     958141,   Seg_Num: 0
  POINT_RA:        248.804d {+16h 35m 13s} (J2000)
  POINT_DEC:       +41.673d {+41d 40' 24"} (J2000)
  POINT_ROLL:      98.573d
  IMG_START_DATE:  18903 TJD;    55 DOY;   20/02/24
  IMG_START_TIME:  12548.35 SOD {03:29:08.35} UT,   259.1 [sec] since BAT Trigger Time
  FILTER:          7, U
  BKG_MEAN:        0.386
  N_STARS:         57
  X_OFFSET:        186 [pixels]
  Y_OFFSET:        338 [pixels]
  X_MAX:           1625 [pixels]
  Y_MAX:           1777 [pixels]
  DET_THRESH:      6
  PHOTO_THRESH:    2
  SL_URL:          sw00958141000msufc0259.fits
  SUN_POSTN:       336.82d {+22h 27m 18s}   -9.68d {-09d 40' 52"}
  SUN_DIST:         94.83 [deg]   Sun_angle= 5.9 [hr] (West of Sun)
  MOON_POSTN:      343.69d {+22h 54m 45s}  -11.88d {-11d 52' 34"}
  MOON_DIST:       101.35 [deg]
  MOON_ILLUM:      0 [%]
  GAL_COORDS:       65.87, 42.49 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:      234.20, 62.50 [deg] ecliptic lon,lat of the pointing direction
  COMMENTS:        SWIFT-UVOT Source List.  
  

  
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Mon 24 Feb 20 03:38:22 UT
  NOTICE_TYPE:     Swift-UVOT Image
  TRIGGER_NUM:     958141,   Seg_Num: 0
  POINT_RA:        248.804d {+16h 35m 13s} (J2000)
  POINT_DEC:       +41.673d {+41d 40' 24"} (J2000)
  ROLL:            98.573d
  IMG_START_DATE:  18903 TJD;    55 DOY;   20/02/24
  IMG_START_TIME:  12548.35 SOD {03:29:08.35} UT,   259.1 [sec] since BAT Trigger Time
  FILTER:          7, U
  EXPOSURE_ID:     604207772
  X_OFFSET:        745 [pixels]
  Y_OFFSET:        897 [pixels]
  WIDTH:           160 [pixels]
  HEIGHT:          160 [pixels]
  X_GRB_POS:       905
  Y_GRB_POS:       1057
  BINNING_INDEX:   1
  IM_URL:          sw00958141000msuni0284.fits
  SUN_POSTN:       336.82d {+22h 27m 18s}   -9.68d {-09d 40' 51"}
  SUN_DIST:         94.83 [deg]   Sun_angle= 5.9 [hr] (West of Sun)
  MOON_POSTN:      343.69d {+22h 54m 47s}  -11.87d {-11d 52' 22"}
  MOON_DIST:       101.36 [deg]
  MOON_ILLUM:      0 [%]
  GAL_COORDS:       65.87, 42.49 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:      234.20, 62.50 [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 24 Feb 20 03:37:31 UT
  NOTICE_TYPE:     Swift-UVOT Processed Source List
  TRIGGER_NUM:     958141,   Seg_Num: 0
  POINT_RA:        248.804d {+16h 35m 13s} (J2000)
  POINT_DEC:       +41.673d {+41d 40' 24"} (J2000)
  POINT_ROLL:      98.573d
  IMG_START_DATE:  18903 TJD;    55 DOY;   20/02/24
  IMG_START_TIME:  12548.35 SOD {03:29:08.35} UT,   259.1 [sec] since BAT Trigger Time
  FILTER:          7, U
  BKG_MEAN:        0.386
  N_STARS:         57
  X_OFFSET:        186 [pixels]
  Y_OFFSET:        338 [pixels]
  X_MAX:           1625 [pixels]
  Y_MAX:           1777 [pixels]
  DET_THRESH:      6
  PHOTO_THRESH:    2
  SL_URL:          sw00958141000msufc0259.fits
  SUN_POSTN:       336.82d {+22h 27m 18s}   -9.68d {-09d 40' 52"}
  SUN_DIST:         94.83 [deg]   Sun_angle= 5.9 [hr] (West of Sun)
  MOON_POSTN:      343.69d {+22h 54m 45s}  -11.88d {-11d 52' 31"}
  MOON_DIST:       101.35 [deg]
  MOON_ILLUM:      0 [%]
  GAL_COORDS:       65.87, 42.49 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:      234.20, 62.50 [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:     Mon 24 Feb 20 03:37:51 UT
  NOTICE_TYPE:     Swift-XRT Position UPDATE
  TRIGGER_NUM:     958141,   Seg_Num: 0
  GRB_RA:          248.7667d {+16h 35m 04.00s} (J2000),
                   248.9320d {+16h 35m 43.67s} (current),
                   248.3568d {+16h 33m 25.62s} (1950)
  GRB_DEC:         +41.6122d {+41d 36' 43.9"} (J2000),
                   +41.5717d {+41d 34' 18.2"} (current),
                   +41.7140d {+41d 42' 50.2"} (1950)
  GRB_ERROR:       2.9 [arcsec radius, statistical plus systematic, 90% containment]
  GRB_INTEN:       1.00e-10 [erg/cm2/sec]
  GRB_SIGNIF:      10.00 [sigma]
  IMG_START_DATE:  18903 TJD;    55 DOY;   20/02/24
  IMG_START_TIME:  12394.00 SOD {03:26:34.00} UT,   104.7 [sec] since BAT Trigger Time
  TAM[0-3]:        100.00 100.00 100.00 100.00
  AMPLIFIER:       1
  WAVEFORM:        31
  SUN_POSTN:       336.82d {+22h 27m 18s}   -9.68d {-09d 40' 52"}
  SUN_DIST:         94.84 [deg]   Sun_angle= 5.9 [hr] (West of Sun)
  MOON_POSTN:      343.69d {+22h 54m 46s}  -11.87d {-11d 52' 27"}
  MOON_DIST:       101.38 [deg]
  MOON_ILLUM:      0 [%]
  GAL_COORDS:       65.79, 42.52 [deg] galactic lon,lat of the burst
  ECL_COORDS:      234.19, 62.44 [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 0.58% < P(seren) < 1.1%.  
  

• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Mon 24 Feb 20 03:38:38 UT
  NOTICE_TYPE:     Swift-UVOT Processed Image
  TRIGGER_NUM:     958141,   Seg_Num: 0
  POINT_RA:        248.804d {+16h 35m 13s} (J2000)
  POINT_DEC:       +41.673d {+41d 40' 24"} (J2000)
  ROLL:            98.573d
  IMG_START_DATE:  18903 TJD;    55 DOY;   20/02/24
  IMG_START_TIME:  12548.35 SOD {03:29:08.35} UT,   259.1 [sec] since BAT Trigger Time
  FILTER:          7, U
  EXPOSURE_ID:     604207772
  X_OFFSET:        745 [pixels]
  Y_OFFSET:        897 [pixels]
  WIDTH:           160 [pixels]
  HEIGHT:          160 [pixels]
  X_GRB_POS:       905
  Y_GRB_POS:       1057
  BINNING_INDEX:   1
  IM_URL:          sw00958141000msuni0284.fits
  SUN_POSTN:       336.82d {+22h 27m 18s}   -9.68d {-09d 40' 51"}
  SUN_DIST:         94.83 [deg]   Sun_angle= 5.9 [hr] (West of Sun)
  MOON_POSTN:      343.70d {+22h 54m 47s}  -11.87d {-11d 52' 19"}
  MOON_DIST:       101.36 [deg]
  MOON_ILLUM:      0 [%]
  GAL_COORDS:       65.87, 42.49 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:      234.20, 62.50 [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 #27172
  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-Kislovodsk robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the Swift GRB200224.14 (trigger No 958141,16h 35m 10.56s , +41d 40m 30.0s, R=0.05) errorbox 17 sec after notice time and 90 sec after trigger time at 2020-02-24 03:26:19 UT, with upper limit up to 13.8 mag. Observations started at twilight. The observations began at zenith distance = 2 deg. The sun altitude is -6.3 deg.
  The galactic latitude b = 42 deg., longitude l = 66 deg.
  Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1295946
  We obtain a following upper limits.

   
  Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
  _________|_____________________|_____|_______|______|________
  
        95 |   MASTER-Kislovodsk |  P- |    10 | 13.8 |        
        95 |   MASTER-Kislovodsk |  P| |    10 | 13.0 |        
  

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

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Mon 24 Feb 20 03:43:21 UT
  NOTICE_TYPE:     Swift-UVOT Processed Source List
  TRIGGER_NUM:     958141,   Seg_Num: 0
  POINT_RA:        248.804d {+16h 35m 13s} (J2000)
  POINT_DEC:       +41.674d {+41d 40' 25"} (J2000)
  POINT_ROLL:      98.573d
  IMG_START_DATE:  18903 TJD;    55 DOY;   20/02/24
  IMG_START_TIME:  13150.35 SOD {03:39:10.35} UT,   861.1 [sec] since BAT Trigger Time
  FILTER:          10, White
  BKG_MEAN:        1.621
  N_STARS:         102
  X_OFFSET:        186 [pixels]
  Y_OFFSET:        338 [pixels]
  X_MAX:           1625 [pixels]
  Y_MAX:           1777 [pixels]
  DET_THRESH:      11
  PHOTO_THRESH:    5
  SL_URL:          sw00958141000msufc0861.fits
  SUN_POSTN:       336.83d {+22h 27m 19s}   -9.68d {-09d 40' 47"}
  SUN_DIST:         94.83 [deg]   Sun_angle= 5.9 [hr] (West of Sun)
  MOON_POSTN:      343.73d {+22h 54m 56s}  -11.86d {-11d 51' 30"}
  MOON_DIST:       101.38 [deg]
  MOON_ILLUM:      0 [%]
  GAL_COORDS:       65.88, 42.49 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:      234.20, 62.50 [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:     Mon 24 Feb 20 03:45:08 UT
  NOTICE_TYPE:     Swift-UVOT Image
  TRIGGER_NUM:     958141,   Seg_Num: 0
  POINT_RA:        248.804d {+16h 35m 13s} (J2000)
  POINT_DEC:       +41.674d {+41d 40' 25"} (J2000)
  ROLL:            98.573d
  IMG_START_DATE:  18903 TJD;    55 DOY;   20/02/24
  IMG_START_TIME:  13150.35 SOD {03:39:10.35} UT,   861.1 [sec] since BAT Trigger Time
  FILTER:          10, White
  EXPOSURE_ID:     604208374
  X_OFFSET:        745 [pixels]
  Y_OFFSET:        897 [pixels]
  WIDTH:           160 [pixels]
  HEIGHT:          160 [pixels]
  X_GRB_POS:       905
  Y_GRB_POS:       1057
  BINNING_INDEX:   1
  IM_URL:          sw00958141000msuni0886.fits
  SUN_POSTN:       336.83d {+22h 27m 19s}   -9.68d {-09d 40' 45"}
  SUN_DIST:         94.83 [deg]   Sun_angle= 5.9 [hr] (West of Sun)
  MOON_POSTN:      343.75d {+22h 55m 00s}  -11.85d {-11d 51' 11"}
  MOON_DIST:       101.39 [deg]
  MOON_ILLUM:      0 [%]
  GAL_COORDS:       65.88, 42.49 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:      234.20, 62.50 [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 24 Feb 20 03:45:17 UT
  NOTICE_TYPE:     Swift-UVOT Processed Image
  TRIGGER_NUM:     958141,   Seg_Num: 0
  POINT_RA:        248.804d {+16h 35m 13s} (J2000)
  POINT_DEC:       +41.674d {+41d 40' 25"} (J2000)
  ROLL:            98.573d
  IMG_START_DATE:  18903 TJD;    55 DOY;   20/02/24
  IMG_START_TIME:  13150.35 SOD {03:39:10.35} UT,   861.1 [sec] since BAT Trigger Time
  FILTER:          10, White
  EXPOSURE_ID:     604208374
  X_OFFSET:        745 [pixels]
  Y_OFFSET:        897 [pixels]
  WIDTH:           160 [pixels]
  HEIGHT:          160 [pixels]
  X_GRB_POS:       905
  Y_GRB_POS:       1057
  BINNING_INDEX:   1
  IM_URL:          sw00958141000msuni0886.fits
  SUN_POSTN:       336.83d {+22h 27m 19s}   -9.68d {-09d 40' 45"}
  SUN_DIST:         94.83 [deg]   Sun_angle= 5.9 [hr] (West of Sun)
  MOON_POSTN:      343.75d {+22h 55m 00s}  -11.85d {-11d 51' 09"}
  MOON_DIST:       101.39 [deg]
  MOON_ILLUM:      0 [%]
  GAL_COORDS:       65.88, 42.49 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:      234.20, 62.50 [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 #27173
  T. N. Ukwatta (LANL), E. Ambrosi (INAF-IASFPA), A. D'Ai (INAF-IASFPA), V. D'Elia (SSDC), J. A. Kennea (PSU), N. J. Klingler (PSU), S. Laha (GSFC/UMBC/CRESST), A. Y. Lien (GSFC/UMBC) and D. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift Observatory Team:
  At 03:24:49 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 200224A (trigger=958141). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 248.794, +41.675 which is

     RA(J2000) = 16h 35m 11s
     Dec(J2000) = +41d 40' 31"
  

  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 30 sec. The peak count rate was ~1000 counts/sec (15-350 keV), at ~3 sec after the trigger.
  The XRT began observing the field at 03:26:26.9 UT, 97.7 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 248.7668, 41.6123 which is equivalent to:

     RA(J2000)  = 16h 35m 04.04s
     Dec(J2000) = +41d 36' 44.1"
  

  with an uncertainty of 2.9 arcseconds (radius, 90% containment). This location is 237 arcseconds from the BAT onboard position. 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 consistent with the Galactic value of 8.91 x 10^19 cm^-2 (Willingale et al. 2013).
  UVOT results will be reported later.
  Burst Advocate for this burst is T. N. Ukwatta (tilan.ukwatta 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 #27174
  The Fermi GBM team reports the detection of a likely LONG GRB
  At 05:05:49 UT on 24 Feb 2020, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 200224A (trigger 604213554.278888 / 200224212).
  The on-ground calculated location, using the Fermi GBM trigger data, is RA = 177.9, Dec = -28.9 (J2000 degrees, equivalent to J2000 11h 51m, -28d 53'), with a statistical uncertainty of 3.1 degrees.
  The angle from the Fermi LAT boresight is 23.0 degrees.
  The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200224212/quicklook/glg_skymap_all_bn200224212.png
  The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200224212/quicklook/glg_healpix_all_bn200224212.fit
  The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200224212/quicklook/glg_lc_medres34_bn200224212.gif
  
• GCN Circular #27176
  A. Sota, E. Fernandez-Garcia, Y.-D. Hu and A. J. Castro-Tirado (IAA-CSIC), A. Castellon, I. Carrasco-Garcia and C. Perez del Pulgar (UMA), on behalf of a larger collaboration, report:
  Following the detection of GRB 200224A by Swift (Ukwatta  et al., GCNC 27173), the 0.3cm robotic telescope at the BOOTES-1 astronomical station at INTA-CEDEA in Huelva (Spain) started gathering images at 03:26:27 UT, 40s after the alert and 118s after the onset of the burst. No optical transient is detected in the single images with a limiting magnitude of 14 (consistent with the MASTER upper limit, Lipunov et al., GCNC 27172). Further data reduction is ongoing.
  Deeper exposures were obtained with the 1.5m telescope at Observatorio de Sierra Nevada starting at 05:35 UT (i.e. 2.1 h post burst).  We find an optical source consistent with the Swift/XRT position,  at coordinates (RA & Dec, J2000)  = 16:35:04.11 +41:36:42 (+/- 1”). The preliminary magnitude is R = 22. Further observations are planned to confirm whether this is the optical afterglow to GRB 200224A.
  This message can be quoted.
• GCN Circular #27177
  B. Stecklum, S. Klose, A. Nicuesa Guelbenzu, and S. Melnikov (all Tautenburg) report:
  We observed the field of GRB 200224A (T0=03:24:49 UT; Ukwatta et al., GCN 27173) with the Tautenburg 1.34m Schmidt telescope equipped with the TAUKAM 6k x 6k CCD camera and the wide V-band filter (VB). The transmission curve of this filter closely follows the Gaia GBP filter. Observations started at 04:09:53 UT and consisted of 5x3 min exposures.
  Based on several Gaia DR2 stars in the field within 1 arcmin radius about the afterglow position, we measure for the optical transient (Sota et al., GCN 27176) at RA, DEC (J2000) = 16:35:04.11, +41:36:42.4 (+/- 0.5 arcsec) the following preliminary Vega magnitude:
  mean time t = Feb 24, 04:18:01 UT; t-T0 = 53m 12s; VB = 21.83 +/- 0.10.
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Mon 24 Feb 20 14:53:25 UT
  NOTICE_TYPE:     Swift-UVOT Position
  TRIGGER_NUM:     958141,   Seg_Num: 0
  GRB_RA:          248.7674d {+16h 35m 04.17s} (J2000),
                   248.9327d {+16h 35m 43.84s} (current),
                   248.3575d {+16h 33m 25.79s} (1950)
  GRB_DEC:         +41.6118d {+41d 36' 42.4"} (J2000),
                   +41.5713d {+41d 34' 16.7"} (current),
                   +41.7136d {+41d 42' 48.7"} (1950)
  GRB_ERROR:       1.1 [arcsec radius, statistical only]
  GRB_MAG:         18.45 +/- 0.40 [mag]
  FILTER:          10, White
  IMG_START_DATE:  18903 TJD;    55 DOY;   20/02/24
  IMG_START_TIME:  12387.00 SOD {03:26:27.00} UT,   97.7 [sec] since BAT Trigger Time
  SUN_POSTN:       337.27d {+22h 29m 05s}   -9.51d {-09d 30' 29"}
  SUN_DIST:         95.06 [deg]   Sun_angle= 5.9 [hr] (West of Sun)
  MOON_POSTN:      349.04d {+23h 16m 09s}   -9.87d {-09d 52' 10"}
  MOON_DIST:       104.07 [deg]
  MOON_ILLUM:      1 [%]
  GAL_COORDS:       65.79, 42.52 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      234.19, 62.44 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        SWIFT UVOT Position Notice.  
  COMMENTS:        This Notice was ground-generated -- not flight-generated.  
  COMMENTS:        Result based on srclist data.  
  COMMENTS:        Notice generated automatically.  
  

• GCN Circular #27179
  J. D. Gropp (PSU), J.A. Kennea (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), A. Tohuvavohu (U. Toronto), and report on behalf of the Swift-XRT team: report on behalf of the Swift-XRT team:
  We have analysed 12 ks of XRT data for the Swift-detected burst GRB 200224A, from 105 s to 34.0 ks after the Swift trigger. The data are entirely in Photon Counting (PC) mode. Using 4055 s of PC mode data and 4 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 248.76655, +41.61133 which is equivalent to:

  RA (J2000): 16h 35m 03.97s
  Dec(J2000): +41d 36' 40.8"
  

  with an uncertainty of 1.7 arcsec (radius, 90% confidence). This position is 4.0 arcmin from the Swift position.
  The light curve can be modelled with a power-law decay with a decay index of alpha=0.86 (+0.10, -0.09).
  A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.09 (+0.39, -0.29). The best-fitting absorption column is 3.2 (+7.4, -2.3) x 10^20 cm^-2, consistent with the Galactic value of 8.9 x 10^19 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.0 x 10^-11 (3.3 x 10^-11) erg cm^-2 count^-1.
  A summary of the PC-mode spectrum is thus:

  Total column:	     3.2 (+7.4, -2.3) x 10^20 cm^-2
  Galactic foreground: 8.9 x 10^19 cm^-2
  Excess significance: <1.6 sigma
  Photon index:	     2.09 (+0.39, -0.29)
  

  If the light curve continues to decay with a power-law decay index of 0.86, the count rate at T+24 hours will be 9.9 x 10^-4 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.0 x 10^-14 (3.3 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/00958141.
  This circular is an official product of the Swift-XRT team.
• GCN Circular #27182
  F. E. Marshall (NASA/GSFC) and T. N. Ukwatta (LANL) report on behalf of the Swift/UVOT team:
  The Swift/UVOT began settled observations of the field of GRB 200224A 101 s after the BAT trigger (Ukwatta et al., GCN Circ. 27173). A source consistent with the enhanced XRT position (Gropp et al., GCNC 27179) and the optical positions reported by Sota et al. (GCNC 27176) and Stecklum et al. (GCNC 27177) is detected in the initial UVOT exposures. The source is very close to the edge of the image in the first exposure at 101 s after the BAT trigger, and further analysis is required to determine an accurate intensity for that exposure.
  The preliminary UVOT position is:

      RA  (J2000) =  16:35:04.14 = 248.76727 (deg.)
      Dec (J2000) = +41:36:42.3  =  41.61174 (deg.)
  

  with an estimated uncertainty of 0.43 arc sec. (radius, 90% confidence).
  Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:

  Filter         T_start(s)   T_stop(s)      Exp(s)           Mag
  
  u                  259          509          246         18.75 +/- 0.10
  white              861         1011          147         20.57 +/- 0.20
  w1                5978        19265         1098        >20.7
  m2                5772        18542         1279        >21.4
  w2                5363        30092         1953        >21.9
  

  The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.005 in the direction of the burst (Schlegel et al. 1998).
• GCN Circular #27189
  Rosa L. Becerra (UNAM), Margarita Pereyra (UNAM), Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), Jes�s Gonz�lez (UNAM), Carlos Rom�n-Z��iga (UNAM), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.), and Vicki Toy (UMD) report:
  We observed the field of GRB 200224A (Palmer D., et al., GCN 27173) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astron�mico Nacional on Sierra San Pedro M�rtir from 2020/02 24.36 to 2020/02 24.54 UTC (5.33 to 9.66 hours after the BAT trigger), obtaining a total of 3.44 hours exposure in the r and i bands.
  For a source within the Swift-XRT error circle, in comparison with the SDSS DR9 and 2MASS catalogs, we obtain the following upper limits (3-sigma):

    r > 23.88
    i > 23.84
  

  These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB.
  Castro-Tirado et al. (GCN 27176) and Stecklum et al. (GCN 27177) report an afterglow candidate at roughly magnitude 22 at about 1 and 2 hours after the burst. Our observations show subsequent fading of this source and confirm that it is the afterglow.
  We thank the staff of the Observatorio Astron�mico Nacional in San Pedro M�rtir.
• GCN Circular #27191
  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 200224A (Ukwatta et al., GCN 27173) with the LCO 1-m Sinistro instrument at the McDonald Observatory, Texas, USA site, on February 24, from 12:01 to 12:18 UT (corresponding to 8.62 to 8.90 hours from the GRB trigger time) with the Bessel I and R filters.
  We performed a series of 5x120s exposures in I and 3x120s in R. We do not detect any sources in the individual frames (nor in stacked images) in the Swift error region. Using the USNO-B.1 catalog as reference, we obtain the following 3-sigma upper limits:

  R > 19.85
  
  I > 19.05
  

  R.S. is funded by NSF AST grant #1831682
• GCN Circular #27194
  A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF), S. Laha (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-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 200224A (trigger #958141) (Ukwatta et al., GCN Circ. 27173). The BAT ground-calculated position is RA, Dec = 248.743, 41.666 deg which is

     RA(J2000)  =  16h 34m 58.4s
     Dec(J2000) = +41d 39' 57.2"
  

  with an uncertainty of 3.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%.
  The mask-weighted light curve shows a weak pulse from ~T0 to ~T+5 s, followed by some weaker emission that lasts till ~T+50 s. T90 (15-350 keV) is 45.0 +- 9.2 sec (estimated error including systematics).
  The time-averaged spectrum from T-0.79 to T+49.21 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.69 +- 0.51. The fluence in the 15-150 keV band is 2.9 +- 0.9 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+2.21 sec in the 15-150 keV band is 0.4 +- 0.1 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/958141/BA/
• GCN Circular #27222
  J. F. Agui Fernandez, M. Blazek, D. A. Kann (all HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), C. C. Thoene (HETH/IAA-CSIC), E. Gallego-Cano, and A. Guijarro (both CAHA) report:
  We observed the field of the Swift-detected GRB 200224A (Ukwatta et al., GCN #21173) with the 2.2m telescope at CAHA, Almeria, Spain. We obtained 5 x 120 s each in Rc and Ic.
  At the position of the optical afterglow reported by Sota et al. (GCN #27176), Stecklum et al. (GCN #21177), and Marshall & Ukwatta (GCN #27182), we clearly detect a source in each stack image.
  We measure Rc = 21.60 +/- 0.06 mag at 0.03702 days after the GRB, and Ic = 21.31 +/- 0.09 mag at 0.05794 days after the GRB (Vega magnitudes), in good agreement with the measurements of Tautenburg at an earlier time (GCN #27177) and OSN at a later time (GCN #27176).
  We note the optical afterglow is very faint (see also Becerra et al., GCN #27189), but the clear detection in u by Swift/UVOT (GCN #27182) as well as the blue Rc-Ic color we find indicates this GRB is neither at high redshift nor particularly extinguished (see also the XRT results, Gropp et al., GCN #27179), it is likely just intrinsically faint.
• GCN Circular #27240
  S. Belkin (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), E. Mazaeva (IKI), A. Volnova (IKI) report on behalf of IKI-GRB-FuN:
  We observed the field of GRB 200224A (Ukwatta et al., GCN 27173; Fermi GBM team GCN 27174) with AZT-33IK telescope of Sayan observatory (Mondy) starting on Feb. 26 (UT) 17:24:49. We did not detect the optical afterglow (Sota et al., GCN 27176; Stecklum et al., GCN 27177; Marshall et al., GCN 27182; Becerra et al., GCN 27182; Fernandez et al., GCN 27222). Preliminary photometry of the field is following.

  Date UT start,      t-T0    Filter Exp.   OT UL(3sigma)
                       (mid, days)    (s)
  2020-02-26 17:24:49 2.60348 R      29*120 n/d 22.6
  

  Photometry is based on the USNO-B1.0 nearby stars.