Gamma-ray Burst 191004B

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN/BACODINE POSITION NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Fri 04 Oct 19 21:33:56 UT
  NOTICE_TYPE:     Swift-BAT GRB Position
  TRIGGER_NUM:     927839,   Seg_Num: 0
  GRB_RA:           49.177d {+03h 16m 42s} (J2000),
                    49.361d {+03h 17m 27s} (current),
                    48.710d {+03h 14m 51s} (1950)
  GRB_DEC:         -39.613d {-39d 36' 46"} (J2000),
                   -39.541d {-39d 32' 28"} (current),
                   -39.796d {-39d 47' 44"} (1950)
  GRB_ERROR:       3.00 [arcmin radius, statistical only]
  GRB_INTEN:       2163 [cnts]    Image_Peak=168 [image_cnts]
  TRIGGER_DUR:     0.512 [sec] 
  TRIGGER_INDEX:   124     E_range: 25-100 keV
  BKG_INTEN:       22435 [cnts]
  BKG_TIME:        77608.30 SOD {21:33:28.30} UT
  BKG_DUR:         8 [sec]
  GRB_DATE:        18760 TJD;   277 DOY;   19/10/04
  GRB_TIME:        77621.68 SOD {21:33:41.68} UT
  GRB_PHI:         -133.04 [deg]
  GRB_THETA:        13.94 [deg]
  SOLN_STATUS:     0x3
  RATE_SIGNIF:     18.52 [sigma]
  IMAGE_SIGNIF:    9.55 [sigma]
  MERIT_PARAMS:     +1  +0  +0  -1  +2  +0  +0  +0 +54  +0 
  SUN_POSTN:       190.45d {+12h 41m 49s}   -4.50d {-04d 29' 48"}
  SUN_DIST:        123.25 [deg]   Sun_angle= 9.4 [hr] (West of Sun)
  MOON_POSTN:      272.38d {+18h 09m 31s}  -22.38d {-22d 23' 00"}
  MOON_DIST:       106.20 [deg]
  MOON_ILLUM:      42 [%]
  GAL_COORDS:      244.87,-57.48 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:       29.18,-54.77 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        SWIFT-BAT GRB Coordinates.  
  COMMENTS:        This is a rate trigger.  
  COMMENTS:        A point_source was found.  
  COMMENTS:        This does not match any source in the on-board catalog.  
  COMMENTS:        This does not match any source in the ground catalog.  
  COMMENTS:        This is a GRB.  
  COMMENTS:        This trigger occurred at longitude,latitude = 109.82,18.90 [deg].  
  

• red DSS finding chart ps-file
  
  
• GCN NOTICE
  

   
  TITLE:          GCN/INTEGRAL NOTICE
  NOTICE_DATE:    Fri 04 Oct 19 21:34:35 UT
  NOTICE_TYPE:    INTEGRAL SPI ACS Trigger
  TRIGGER_NUM:    8384,   Sub_Num: 0
  GRB_INTEN:      9.29 [sigma]   
  GRB_TIME:       77625.57 SOD {21:33:45.57} UT
  GRB_DATE:       18760 TJD;   277 DOY;   19/10/04
  COMMENTS:       INTEGRAL SPI_ACS GRB Trigger.
  COMMENTS:       Time_Scale=0.8000 and Time_Error=0.4000.
  COMMENTS:
  COMMENTS:       NOTE: This SPIACS event is temporally(4.0<100sec) coincident with the SWIFT_BAT event (trignum=927839).
  COMMENTS:
  COMMENTS:       The SPIACS lightcurve can be found at:
  COMMENTS:       ftp://isdcarc.unige.ch/arc/FTP/ibas/spiacs/2019-10/2019-10-04T21-33-45.3749-02120-27536-0.lc
  

• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Fri 04 Oct 19 21:35:31 UT
  NOTICE_TYPE:     Swift-XRT Processed Image
  TRIGGER_NUM:     927839,   Seg_Num: 0
  GRB_RA:           49.2021d {+03h 16m 48.5s} (J2000),
                    49.3863d {+03h 17m 32.7s} (current),
                    48.7361d {+03h 14m 56.6s} (1950)
  GRB_DEC:         -39.6353d {-39d 38' 07.0"} (J2000),
                   -39.5636d {-39d 33' 48.8"} (current),
                   -39.8181d {-39d 49' 05.0"} (1950)
  GRB_ERROR:       5.0 [arcsec, radius, statistical plus systematic]
  GRB_INTEN:       74 [cnts]
  IMG_START_DATE:  18760 TJD;   277 DOY;   19/10/04
  IMG_START_TIME:  77679.36 SOD {21:34:39.36} UT,   57.7 [sec] since BAT Trigger Time
  CENTROID_X:      246.94,  raw= 247  [pixels]
  CENTROID_Y:      287.07,  raw= 287  [pixels]
  ROLL:            131.75 [deg]
  GAIN:            1
  MODE:            3, Long Image mode
  WAVEFORM:        134
  EXPO_TIME:       2.50 [sec]
  GRB_POS_XRT_Y:   -25.99
  GRB_POS_XRT_Z:   -142.51
  IMAGE_URL:       sw00927839000msxps_rw.img
  SUN_POSTN:       190.46d {+12h 41m 49s}   -4.50d {-04d 29' 49"}
  SUN_DIST:        123.22 [deg]   Sun_angle= 9.4 [hr] (West of Sun)
  MOON_POSTN:      272.39d {+18h 09m 35s}  -22.38d {-22d 23' 03"}
  MOON_DIST:       106.18 [deg]
  MOON_ILLUM:      42 [%]
  GAL_COORDS:      244.90,-57.45 [deg] galactic lon,lat of the burst
  ECL_COORDS:       29.19,-54.80 [deg] ecliptic lon,lat of the burst
  COMMENTS:        SWIFT-XRT Processed Image.  
  

  
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Fri 04 Oct 19 21:35:22 UT
  NOTICE_TYPE:     Swift-XRT Image
  TRIGGER_NUM:     927839,   Seg_Num: 0
  GRB_RA:           49.2021d {+03h 16m 48.5s} (J2000),
                    49.3863d {+03h 17m 32.7s} (current),
                    48.7361d {+03h 14m 56.6s} (1950)
  GRB_DEC:         -39.6353d {-39d 38' 07.0"} (J2000),
                   -39.5636d {-39d 33' 48.8"} (current),
                   -39.8181d {-39d 49' 05.0"} (1950)
  GRB_ERROR:       5.0 [arcsec, radius, statistical plus systematic]
  GRB_INTEN:       74 [cnts]
  IMG_START_DATE:  18760 TJD;   277 DOY;   19/10/04
  IMG_START_TIME:  77679.36 SOD {21:34:39.36} UT,   57.7 [sec] since BAT Trigger Time
  CENTROID_X:      246.94,  raw= 247  [pixels]
  CENTROID_Y:      287.07,  raw= 287  [pixels]
  ROLL:            131.75 [deg]
  GAIN:            1
  MODE:            3, Long Image mode
  WAVEFORM:        134
  EXPO_TIME:       2.50 [sec]
  GRB_POS_XRT_Y:   -25.99
  GRB_POS_XRT_Z:   -142.51
  IMAGE_URL:       sw00927839000msxps_rw.img
  SUN_POSTN:       190.46d {+12h 41m 49s}   -4.50d {-04d 29' 49"}
  SUN_DIST:        123.22 [deg]   Sun_angle= 9.4 [hr] (West of Sun)
  MOON_POSTN:      272.39d {+18h 09m 34s}  -22.38d {-22d 23' 03"}
  MOON_DIST:       106.18 [deg]
  MOON_ILLUM:      42 [%]
  GAL_COORDS:      244.90,-57.45 [deg] galactic lon,lat of the burst
  ECL_COORDS:       29.19,-54.80 [deg] ecliptic lon,lat of the burst
  COMMENTS:        SWIFT-XRT Image.  
  

  
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Fri 04 Oct 19 21:35:12 UT
  NOTICE_TYPE:     Swift-XRT Position
  TRIGGER_NUM:     927839,   Seg_Num: 0
  GRB_RA:           49.2021d {+03h 16m 48.50s} (J2000),
                    49.3863d {+03h 17m 32.70s} (current),
                    48.7361d {+03h 14m 56.66s} (1950)
  GRB_DEC:         -39.6353d {-39d 38' 07.0"} (J2000),
                   -39.5636d {-39d 33' 48.8"} (current),
                   -39.8181d {-39d 49' 05.0"} (1950)
  GRB_ERROR:       5.2 [arcsec radius, statistical plus systematic, 90% containment]
  GRB_INTEN:       1.81e-09 [erg/cm2/sec]
  GRB_SIGNIF:      8.60 [sigma]
  IMG_START_DATE:  18760 TJD;   277 DOY;   19/10/04
  IMG_START_TIME:  77679.36 SOD {21:34:39.36} UT,   57.7 [sec] since BAT Trigger Time
  TAM[0-3]:        327.64 237.20 261.62 243.44
  AMPLIFIER:       2
  WAVEFORM:        134
  SUN_POSTN:       190.46d {+12h 41m 49s}   -4.50d {-04d 29' 49"}
  SUN_DIST:        123.22 [deg]   Sun_angle= 9.4 [hr] (West of Sun)
  MOON_POSTN:      272.39d {+18h 09m 34s}  -22.38d {-22d 23' 02"}
  MOON_DIST:       106.18 [deg]
  MOON_ILLUM:      42 [%]
  GAL_COORDS:      244.90,-57.45 [deg] galactic lon,lat of the burst
  ECL_COORDS:       29.19,-54.80 [deg] ecliptic lon,lat of the burst
  COMMENTS:        SWIFT-XRT Coordinates.  
  COMMENTS:        The XRT position is 1.77 arcmin from the BAT position.  
  

• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Fri 04 Oct 19 21:37:40 UT
  NOTICE_TYPE:     Swift-BAT GRB Lightcurve
  TRIGGER_NUM:     927839,   Seg_Num: 0
  GRB_RA:           49.177d {+03h 16m 42s} (J2000),
                    49.361d {+03h 17m 27s} (current),
                    48.710d {+03h 14m 51s} (1950)
  GRB_DEC:         -39.613d {-39d 36' 46"} (J2000),
                   -39.541d {-39d 32' 28"} (current),
                   -39.796d {-39d 47' 44"} (1950)
  GRB_DATE:        18760 TJD;   277 DOY;   19/10/04
  GRB_TIME:        77621.68 SOD {21:33:41.68} UT
  TRIGGER_INDEX:   124
  GRB_PHI:         -133.04 [deg]
  GRB_THETA:        13.94 [deg]
  DELTA_TIME:      -57.00 [sec]
  TRIGGER_DUR:     0.512 [sec] 
  SOLN_STATUS:     0x3
  RATE_SIGNIF:     18.52 [sigma]
  IMAGE_SIGNIF:    9.55 [sigma]
  LC_URL:          sw00927839000msb.lc
  SUN_POSTN:       190.46d {+12h 41m 50s}   -4.50d {-04d 29' 52"}
  SUN_DIST:        123.25 [deg]   Sun_angle= 9.4 [hr] (West of Sun)
  MOON_POSTN:      272.41d {+18h 09m 40s}  -22.39d {-22d 23' 08"}
  MOON_DIST:       106.18 [deg]
  MOON_ILLUM:      42 [%]
  GAL_COORDS:      244.87,-57.48 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:       29.18,-54.77 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        SWIFT-BAT GRB Lightcurve.  
  COMMENTS:           
  COMMENTS:        The next comments were copied from the BAT_POS Notice:  
  COMMENTS:        This is a rate trigger.  
  COMMENTS:        A point_source was found.  
  COMMENTS:        This does not match any source in the on-board catalog.  
  COMMENTS:        This does not match any source in the ground catalog.  
  COMMENTS:        This is a GRB.  
  COMMENTS:        This trigger occurred at longitude,latitude = 109.82,18.90 [deg].  
  

  
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Fri 04 Oct 19 21:37:54 UT
  NOTICE_TYPE:     Swift-UVOT Source List
  TRIGGER_NUM:     927839,   Seg_Num: 0
  POINT_RA:         49.170d {+03h 16m 41s} (J2000)
  POINT_DEC:       -39.603d {-39d 36' 11"} (J2000)
  POINT_ROLL:      131.749d
  IMG_START_DATE:  18760 TJD;   277 DOY;   19/10/04
  IMG_START_TIME:  77690.55 SOD {21:34:50.55} UT,   68.9 [sec] since BAT Trigger Time
  FILTER:          10, White
  BKG_MEAN:        1.491
  N_STARS:         22
  X_OFFSET:        760 [pixels]
  Y_OFFSET:        445 [pixels]
  X_MAX:           1719 [pixels]
  Y_MAX:           1404 [pixels]
  DET_THRESH:      10
  PHOTO_THRESH:    5
  SL_URL:          sw00927839000msufc0068.fits
  SUN_POSTN:       190.46d {+12h 41m 50s}   -4.50d {-04d 29' 52"}
  SUN_DIST:        123.26 [deg]   Sun_angle= 9.4 [hr] (West of Sun)
  MOON_POSTN:      272.42d {+18h 09m 40s}  -22.39d {-22d 23' 08"}
  MOON_DIST:       106.18 [deg]
  MOON_ILLUM:      42 [%]
  GAL_COORDS:      244.85,-57.48 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:       29.18,-54.76 [deg] ecliptic lon,lat of the pointing direction
  COMMENTS:        SWIFT-UVOT Source List.  
  

• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Fri 04 Oct 19 21:38:08 UT
  NOTICE_TYPE:     Swift-UVOT Processed Source List
  TRIGGER_NUM:     927839,   Seg_Num: 0
  POINT_RA:         49.170d {+03h 16m 41s} (J2000)
  POINT_DEC:       -39.603d {-39d 36' 11"} (J2000)
  POINT_ROLL:      131.749d
  IMG_START_DATE:  18760 TJD;   277 DOY;   19/10/04
  IMG_START_TIME:  77690.55 SOD {21:34:50.55} UT,   68.9 [sec] since BAT Trigger Time
  FILTER:          10, White
  BKG_MEAN:        1.491
  N_STARS:         22
  X_OFFSET:        760 [pixels]
  Y_OFFSET:        445 [pixels]
  X_MAX:           1719 [pixels]
  Y_MAX:           1404 [pixels]
  DET_THRESH:      10
  PHOTO_THRESH:    5
  SL_URL:          sw00927839000msufc0068.fits
  SUN_POSTN:       190.46d {+12h 41m 50s}   -4.50d {-04d 29' 52"}
  SUN_DIST:        123.26 [deg]   Sun_angle= 9.4 [hr] (West of Sun)
  MOON_POSTN:      272.42d {+18h 09m 41s}  -22.39d {-22d 23' 09"}
  MOON_DIST:       106.18 [deg]
  MOON_ILLUM:      42 [%]
  GAL_COORDS:      244.85,-57.48 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:       29.18,-54.76 [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:     Fri 04 Oct 19 21:39:12 UT
  NOTICE_TYPE:     Swift-UVOT Image
  TRIGGER_NUM:     927839,   Seg_Num: 0
  POINT_RA:         49.170d {+03h 16m 41s} (J2000)
  POINT_DEC:       -39.603d {-39d 36' 11"} (J2000)
  ROLL:            131.749d
  IMG_START_DATE:  18760 TJD;   277 DOY;   19/10/04
  IMG_START_TIME:  77690.55 SOD {21:34:50.55} UT,   68.9 [sec] since BAT Trigger Time
  FILTER:          10, White
  EXPOSURE_ID:     591917714
  X_OFFSET:        1080 [pixels]
  Y_OFFSET:        765 [pixels]
  WIDTH:           160 [pixels]
  HEIGHT:          160 [pixels]
  X_GRB_POS:       1240
  Y_GRB_POS:       925
  BINNING_INDEX:   1
  IM_URL:          sw00927839000msuni0092.fits
  SUN_POSTN:       190.46d {+12h 41m 50s}   -4.50d {-04d 29' 53"}
  SUN_DIST:        123.26 [deg]   Sun_angle= 9.4 [hr] (West of Sun)
  MOON_POSTN:      272.43d {+18h 09m 43s}  -22.39d {-22d 23' 11"}
  MOON_DIST:       106.17 [deg]
  MOON_ILLUM:      42 [%]
  GAL_COORDS:      244.85,-57.48 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:       29.18,-54.76 [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:     Fri 04 Oct 19 21:39:26 UT
  NOTICE_TYPE:     Swift-UVOT Processed Image
  TRIGGER_NUM:     927839,   Seg_Num: 0
  POINT_RA:         49.170d {+03h 16m 41s} (J2000)
  POINT_DEC:       -39.603d {-39d 36' 11"} (J2000)
  ROLL:            131.749d
  IMG_START_DATE:  18760 TJD;   277 DOY;   19/10/04
  IMG_START_TIME:  77690.55 SOD {21:34:50.55} UT,   68.9 [sec] since BAT Trigger Time
  FILTER:          10, White
  EXPOSURE_ID:     591917714
  X_OFFSET:        1080 [pixels]
  Y_OFFSET:        765 [pixels]
  WIDTH:           160 [pixels]
  HEIGHT:          160 [pixels]
  X_GRB_POS:       1240
  Y_GRB_POS:       925
  BINNING_INDEX:   1
  IM_URL:          sw00927839000msuni0092.fits
  SUN_POSTN:       190.46d {+12h 41m 50s}   -4.50d {-04d 29' 53"}
  SUN_DIST:        123.26 [deg]   Sun_angle= 9.4 [hr] (West of Sun)
  MOON_POSTN:      272.43d {+18h 09m 44s}  -22.39d {-22d 23' 12"}
  MOON_DIST:       106.17 [deg]
  MOON_ILLUM:      42 [%]
  GAL_COORDS:      244.85,-57.48 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:       29.18,-54.76 [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:     Fri 04 Oct 19 21:41:16 UT
  NOTICE_TYPE:     Swift-UVOT Source List
  TRIGGER_NUM:     927839,   Seg_Num: 0
  POINT_RA:         49.166d {+03h 16m 40s} (J2000)
  POINT_DEC:       -39.603d {-39d 36' 11"} (J2000)
  POINT_ROLL:      131.752d
  IMG_START_DATE:  18760 TJD;   277 DOY;   19/10/04
  IMG_START_TIME:  77902.51 SOD {21:38:22.51} UT,   280.8 [sec] since BAT Trigger Time
  FILTER:          7, U
  BKG_MEAN:        0.315
  N_STARS:         4
  X_OFFSET:        760 [pixels]
  Y_OFFSET:        445 [pixels]
  X_MAX:           1719 [pixels]
  Y_MAX:           1404 [pixels]
  DET_THRESH:      6
  PHOTO_THRESH:    2
  SL_URL:          sw00927839000msufc0280.fits
  SUN_POSTN:       190.46d {+12h 41m 50s}   -4.50d {-04d 29' 55"}
  SUN_DIST:        123.27 [deg]   Sun_angle= 9.4 [hr] (West of Sun)
  MOON_POSTN:      272.45d {+18h 09m 48s}  -22.39d {-22d 23' 16"}
  MOON_DIST:       106.16 [deg]
  MOON_ILLUM:      42 [%]
  GAL_COORDS:      244.86,-57.49 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:       29.18,-54.76 [deg] ecliptic lon,lat of the pointing direction
  COMMENTS:        SWIFT-UVOT Source List.  
  

• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Fri 04 Oct 19 21:41:51 UT
  NOTICE_TYPE:     Swift-UVOT Position
  TRIGGER_NUM:     927839,   Seg_Num: 0
  GRB_RA:           49.2045d {+03h 16m 49.08s} (J2000),
                    49.3887d {+03h 17m 33.28s} (current),
                    48.7385d {+03h 14m 57.24s} (1950)
  GRB_DEC:         -39.6342d {-39d 38' 03.1"} (J2000),
                   -39.5625d {-39d 33' 44.8"} (current),
                   -39.8170d {-39d 49' 01.0"} (1950)
  GRB_ERROR:       0.6 [arcsec radius, statistical only]
  GRB_MAG:         18.00 +/- 0.14 [mag]
  FILTER:          10, White
  IMG_START_DATE:  18760 TJD;   277 DOY;   19/10/04
  IMG_START_TIME:  77687.00 SOD {21:34:47.00} UT,   65.3 [sec] since BAT Trigger Time
  SUN_POSTN:       190.46d {+12h 41m 50s}   -4.50d {-04d 29' 56"}
  SUN_DIST:        123.22 [deg]   Sun_angle= 9.4 [hr] (West of Sun)
  MOON_POSTN:      272.46d {+18h 09m 49s}  -22.39d {-22d 23' 17"}
  MOON_DIST:       106.15 [deg]
  MOON_ILLUM:      42 [%]
  GAL_COORDS:      244.90,-57.45 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:       29.20,-54.80 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        SWIFT UVOT Position Notice.  
  COMMENTS:        This Notice was ground-generated -- not flight-generated.  
  COMMENTS:        The UVOT position is 7.9 arcsec from the XRT position.  
  COMMENTS:        Result based on Genie data.  
  COMMENTS:        Notice generated automatically.  
  

• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Fri 04 Oct 19 21:42:25 UT
  NOTICE_TYPE:     Swift-UVOT Image
  TRIGGER_NUM:     927839,   Seg_Num: 0
  POINT_RA:         49.166d {+03h 16m 40s} (J2000)
  POINT_DEC:       -39.603d {-39d 36' 11"} (J2000)
  ROLL:            131.752d
  IMG_START_DATE:  18760 TJD;   277 DOY;   19/10/04
  IMG_START_TIME:  77902.51 SOD {21:38:22.51} UT,   280.8 [sec] since BAT Trigger Time
  FILTER:          7, U
  EXPOSURE_ID:     591917926
  X_OFFSET:        1080 [pixels]
  Y_OFFSET:        765 [pixels]
  WIDTH:           160 [pixels]
  HEIGHT:          160 [pixels]
  X_GRB_POS:       1240
  Y_GRB_POS:       925
  BINNING_INDEX:   1
  IM_URL:          sw00927839000msuni0304.fits
  SUN_POSTN:       190.46d {+12h 41m 50s}   -4.50d {-04d 29' 56"}
  SUN_DIST:        123.27 [deg]   Sun_angle= 9.4 [hr] (West of Sun)
  MOON_POSTN:      272.46d {+18h 09m 51s}  -22.39d {-22d 23' 19"}
  MOON_DIST:       106.15 [deg]
  MOON_ILLUM:      42 [%]
  GAL_COORDS:      244.86,-57.49 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:       29.18,-54.76 [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:     Fri 04 Oct 19 21:42:32 UT
  NOTICE_TYPE:     Swift-UVOT Processed Image
  TRIGGER_NUM:     927839,   Seg_Num: 0
  POINT_RA:         49.166d {+03h 16m 40s} (J2000)
  POINT_DEC:       -39.603d {-39d 36' 11"} (J2000)
  ROLL:            131.752d
  IMG_START_DATE:  18760 TJD;   277 DOY;   19/10/04
  IMG_START_TIME:  77902.51 SOD {21:38:22.51} UT,   280.8 [sec] since BAT Trigger Time
  FILTER:          7, U
  EXPOSURE_ID:     591917926
  X_OFFSET:        1080 [pixels]
  Y_OFFSET:        765 [pixels]
  WIDTH:           160 [pixels]
  HEIGHT:          160 [pixels]
  X_GRB_POS:       1240
  Y_GRB_POS:       925
  BINNING_INDEX:   1
  IM_URL:          sw00927839000msuni0304.fits
  SUN_POSTN:       190.46d {+12h 41m 50s}   -4.50d {-04d 29' 56"}
  SUN_DIST:        123.27 [deg]   Sun_angle= 9.4 [hr] (West of Sun)
  MOON_POSTN:      272.46d {+18h 09m 51s}  -22.39d {-22d 23' 19"}
  MOON_DIST:       106.15 [deg]
  MOON_ILLUM:      42 [%]
  GAL_COORDS:      244.86,-57.49 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:       29.18,-54.76 [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 Circular #25947
  S. B. Cenko (GSFC), S. D. Barthelmy (GSFC), A. P. Beardmore (U Leicester), A. D'Ai (INAF-IASFPA), V. D'Elia (SSDC), J.D. Gropp (PSU), J. A. Kennea (PSU), N. J. Klingler (PSU), N. P. M. Kuin (UCL-MSSL), S Laha (CRESST/GSFC/UMD), A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC), M. J. Moss (GWU), D. M. Palmer (LANL) and A. Tohuvavohu (Toronto) report on behalf of the Neil Gehrels Swift Observatory Team:
  At 21:33:41 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 191004B (trigger=927839). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 49.177, -39.613, which is

     RA(J2000)  =  03h 16m 42s
     Dec(J2000) = -39d 36' 46"
  

  with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows multiple peaks with a total duration of about 40 sec. The peak count rate was ~9500 counts/sec (15-350 keV), at ~3 sec after the trigger.
  The XRT began observing the field at 21:34:39.3 UT, 57.7 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 49.20403, -39.63494 which is equivalent to:

     RA(J2000)  = 03h 16m 48.97s
     Dec(J2000) = -39d 38' 05.8"
  

  with an uncertainty of 3.9 arcseconds (radius, 90% containment). This location is 108 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 http://www.swift.ac.uk/sper. No spectrum from the promptly downlinked event data is yet available to determine the column density.
  The initial flux in the 2.5 s image was 1.81e-09 erg cm^-2 s^-1 (0.2-10 keV).
  UVOT took a finding chart exposure of 150 seconds with the White filter starting 68 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at

    RA(J2000)  =	03:16:49.10 =  49.20458
    DEC(J2000) = -39:38:03.3  = -39.63425
  

  with a 90%-confidence error radius of about 0.62 arc sec. This position is 2.9 arc sec. from the center of the XRT error circle. The estimated magnitude is 18.00 with a 1-sigma error of about 0.14. No correction has been made for the expected extinction corresponding to E(B-V) of 0.02.
  Burst Advocate for this burst is S. B. Cenko (brad.cenko AT nasa.gov). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/)
• GCN Circular #25948
  V. Lipunov, E. Gorbovskoy, V.Kornilov, D.Kuvshinov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, F. Balakin Lomonosov Moscow State University, Sternberg Astronomical Institute, Moscow State University
  D. Buckley, S. Potter, A. Kniazev, M. Kotze South African Astronomical Observatory
  K. Ivanov, O. Gres, N.M. Budnev, S. Yazev, O. Chuvalaev, V. Poleshchuk Irkutsk State University
  A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory
  V. Yurkov, A. Gabovich, Yu. Sergienko Blagoveschensk Educational State University, Blagoveschensk
  R. Podesta, Carlos Lopez and F. Podesta Observatorio Astronomico Felix Aguilar (OAFA)
  Hugo Levato Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)
  R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias
  MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the GRB191004.9 23 sec after notice time and 40 sec after trigger time at 2019-10-04 21:34:21 UT. On our first (10s exposure) set we found 1 optical transient within Swift error-box (ra=49.175 dec=-39.6125 r=0.05) brighter than 16.75.

    T-Tmid      Date      Time       Expt.        Ra                Dec 
  Mag
  ---------|---------------------|-------|-----------------|-----------------|-------
         45   2019-10-04 21:34:21      10   (03h 16m 49.143s , -39d 38m 03.93s)    15.63
  

  The 5-sigma upper limit has been about 16.75mag The message may be cited.
  ====================================================================
  The galactic latitude b = -57 deg., longitude l = 244 deg. The observations made on zenit distance = 42 deg.The moon (42 % bright part) is 15 deg. above the horizon. The distance between moon and object is 106 The sun altitude is -51.4 deg. The object can be observed till sunrise at 2019-10-05 04:09:28
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Fri 04 Oct 19 21:53:20 UT
  NOTICE_TYPE:     Swift-XRT Position UPDATE
  TRIGGER_NUM:     927839,   Seg_Num: 0
  GRB_RA:           49.2038d {+03h 16m 48.91s} (J2000),
                    49.3880d {+03h 17m 33.11s} (current),
                    48.7378d {+03h 14m 57.07s} (1950)
  GRB_DEC:         -39.6348d {-39d 38' 05.2"} (J2000),
                   -39.5631d {-39d 33' 47.0"} (current),
                   -39.8176d {-39d 49' 03.2"} (1950)
  GRB_ERROR:       3.7 [arcsec radius, statistical plus systematic, 90% containment]
  GRB_INTEN:       1.00e-10 [erg/cm2/sec]
  GRB_SIGNIF:      10.00 [sigma]
  IMG_START_DATE:  18760 TJD;   277 DOY;   19/10/04
  IMG_START_TIME:  77830.00 SOD {21:37:10.00} UT,   208.3 [sec] since BAT Trigger Time
  TAM[0-3]:        100.00 100.00 100.00 100.00
  AMPLIFIER:       1
  WAVEFORM:        31
  SUN_POSTN:       190.47d {+12h 41m 52s}   -4.50d {-04d 30' 07"}
  SUN_DIST:        123.23 [deg]   Sun_angle= 9.4 [hr] (West of Sun)
  MOON_POSTN:      272.57d {+18h 10m 16s}  -22.40d {-22d 23' 43"}
  MOON_DIST:       106.09 [deg]
  MOON_ILLUM:      42 [%]
  GAL_COORDS:      244.90,-57.45 [deg] galactic lon,lat of the burst
  ECL_COORDS:       29.20,-54.80 [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:        The probability that this is a serendipitous source in the  
  COMMENTS:        SPER window is 0.11% < P(seren) < 0.58%.  
  

• GCN Circular #25949
  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 191004B (Palmer et al., GCN 25947) with the LCO 1-m Sinistro instrument on September 4, from 21:50 to 22:07 UT (corresponding to 0.11 to 0.4 hours from the GRB trigger time) with the Bessel R filter.
  We performed a series of 5x180s exposures, and we detect a source not present in either USNO-B1.0 or 2MASS surveys consistent with the optical afterglow location (Palmer et al., GCN 25947 ) with the following magnitude:
  R = 18.07 +/- 0.02
  This flux is calibrated against several USNO-B1.0 objects near the GRB location but is not corrected for Galactic Extinction.
  These observations were possible thanks to the USVI NASA-EPSCoR Research Infrastructure Development (RID) grant NNX16AL44A.
• GCN Circular #25951
  A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team.
  Using 162 s of XRT Photon Counting mode data and 1 UVOT images for GRB 191004B, 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 = 49.20398, -39.63502 which is equivalent to:

  RA (J2000): 03h 16m 48.96s
  Dec (J2000): -39d 38' 06.1"
  

  with an uncertainty of 2.0 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 #25954
  K. E. Heintz (Univ. of Iceland), D. B. Malesani (DTU space), and S. Moran (NOT), report on behalf of a larger collaboration:
  We observed the field of the Swift-detected GRB 191004B (Cenko et al., GCN 25947) with the Nordic Optical Telescope (NOT) equipped with StanCAM. We obtained 3x300s exposures with the Bessel R filter starting at 02:30:07 UT on October 5 (i.e. 4.94 hr post-burst). We clearly detect the optical afterglow (Cenko et al., GCN 25947; Lipunov et al., GCN 25948; Strausbaugh & Cucchiara, GCN 25949) and measure a magnitude of R = 20.87 +/- 0.05 mag in the stacked image. We calibrated the photometry assuming for the USNO star at (RA, Dec) = (03:16:54.39, -39:37:41.5) a magnitude of R = 16.97 mag. The derived magnitude for the GRB afterglow is not corrected for the Galactic extinction.
• GCN Circular #25955
  M. Stamatikos (OSU), S. D. Barthelmy (GSFC), S. B. Cenko (GSFC), 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), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
  Using the data set from T-60 to T+243 sec from recent telemetry downlinks, we report further analysis of BAT GRB 191004B (trigger #927839) (Cenko, et al., GCN Circ. 25947). The BAT ground-calculated position is RA, Dec = 49.200, -39.637 deg, which is

     RA(J2000)  =  03h 16m 47.9s
     Dec(J2000) = -39d 38' 15.0"
  

  with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 97%.
  The mask-weighted light curve shows multiple overlapping peaks starting at T-1 sec, peaking at ~T+7 sec, and ending at ~T+45 sec. T90 (15-350 keV) is 37.7 +- 14.9 sec (estimated error including systematics).
  The time-averaged spectrum from T-1.45 to T+56.17 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.10 +- 0.08. The fluence in the 15-150 keV band is 2.5 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+2.75 sec in the 15-150 keV band is 5.0 +- 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/927839/BA/
• GCN Circular #25956
  V. D'Elia (SSDC), J. P. U. Fynbo (DAWN/NBI), L. Izzo (DARK/NBI), D. B. Malesani (DTU Space), K. E. Heintz (Univ. of Iceland), N. R. Tanvir (Univ. Leicester), A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), S. D. Vergani (CNRS -GEPI/Observatorie de Paris) report on behalf of the Stargate collabaration:
  We observed the optical afterglow (Lipunov et al., GCN 25948, Strausbaugh et al., GCN 25949) of the Swift/BAT GRB 191004B (Cenko et al., GCN 25947) using the ESO VLT UT2 (Kueyen) equipped with the X-shooter spectrograph. Our spectra cover the wavelength range 3000-21000 AA, and consist of 6 exposures by 600 s each. The observation mid time was 2019 Oct 05 at about 5:30 UT (8 hr after the GRB). In a 30 s image taken with the acquisition camera on Oct 05.1989 UT, we detect the optical afterglow, for which we measure a magnitude r = 21.23 +- 0.03 AB (calibrated against nearby stars from the SkyMapper catalog; Wolf et al. 2018, PASA, 35, 010; https:doi.org/10.4225/41/593620ad5b574).
  We clearly detect continuum over the full covered wavelength range. A strong absorption is visible around 5474 AA, and an emission feature at 5479 AA, which we identify as due to H I. This is confirmed by the presence of the Ly alpha forest blueward of this wavelength. We also detect other narrower absorption features which we interpret as due to e.g. C IV and Si IV at a common redshift z = 3.503. The continuum is well detected down to ~800 AA rest frame, i.e, below the Lyman limit. We also detect an intervening absorber (Mg II, Fe II) at z=2.137 We acknowledge excellent support from the ESO observing staff in Paranal, in particular Camila Navarrete and Bin Yang.
• GCN Circular #25958
  Alan M. Watson (UNAM), Nat Butler (ASU), Rosa L. Becerra (UNAM), Diego González (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Margarita Pereyra (UNAM), and Eleonora Troja (GSFC) report:
  We observed the field of GRB 191004B (Cenko et al., GCN Circ. 25947) with the COATLI 50-cm telescope and interim imager at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir (http://coatli.astroscu.unam.mx) from 2019-10-05 06:54 to 12:11, obtaining a total of 1.65 hours of exposure in the w filter.
  At the position of the bright afterglow detected by Swift/UVOT (Cenko et al., GCN Circ. 25947), we detect a source with w = 21.47 +/- 0.17.
  Our w magnitudes are calibrated against the Pan-STARRS1 catalog, are on an approximate AB system (Becerra et al., 2019, ApJ, 872, 118), and are not corrected for Galactic extinction in the direction of the GRB.
  We thank the COATLI technical team and the staff of the Observatorio Astronómico Nacional.
• GCN Circular #25960
  P. Schady (Univ. of Bath), J. Balmer (MPE Garching), and A. Nicuesa Guelbenzu (TLS Tautenburg) report:
  We observed the field of GRB 191004B (Swift trigger 927839; Cenko et al., GCN #25947) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla Observatory (Chile).
  Observations started at 02:25 UT on 5th October, 4.9 hours after the GRB trigger. They were performed at an average seeing of 1.5" and at an average airmass of 1.8.
  We detect a single point source consistent with the position of the Swift-XRT and MASTER afterglow (Beardmore et al., GCN # 25951; Lipunov et al., GCN # 25948) in all optical and NIR bands apart from K. In an 8 min exposure, we measure an AB magnitude in the r’ band filter of r' = 20.86 +/- 0.04 mag.
  The optical and NIR afterglow is still clearly detected in a second epoch of observations taken on the night of 6th October, with an AB magnitude r' = 22.10 +/- 0.03 mag.
  The above magnitudes are calibrated again sky-mapper, and not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.01 in the direction of the burst (Schlafly & Finkbeiner 2011).
  We acknowledge the excellent support from Regis Lachaume in La Silla in acquiring these observations.
• GCN Circular #25961
  A. Tohuvavohu (U. Toronto), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-IASFPA), M. Perri (ASDC), J.A. Kennea (PSU), B. Sbarufatti (PSU), and S.B. Cenko report on behalf of the Swift-XRT team:
  We have analysed 8.6 ks of XRT data for GRB 191004B (Cenko et al. GCN Circ. 25947), from 63 s to 102.9 ks after the BAT trigger. The data comprise 142 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN Circ. 25951).
  The light curve can be modelled with an initial power-law decay with an index of alpha=2.9 (+0.6, -0.7), followed by a break at T+94.6 s to an alpha of 1.073 (+0.031, -0.027).
  A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.75 (+0.09, -0.07). The best-fitting absorption column is 1.4 (+6.8, -1.4) x 10^21 cm^-2, at a redshift of 3.503, in addition to the Galactic value of 1.9 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.54 (+0.21, -0.14) and a best-fitting absorption column of 2 (+178, -2) x 10^20 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.2 x 10^-11 (4.3 x 10^-11) erg cm^-2 count^-1.
  A summary of the PC-mode spectrum is thus:

  Galactic foreground: 1.9 x 10^20 cm^-2
  Intrinsic column:    2 (+178, -2) x 10^20 cm^-2 at z=3.503
  Photon index:	     1.54 (+0.21, -0.14)
  

  The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00927839.
  This circular is an official product of the Swift-XRT team.
• GCN Circular #25974
  D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, M. Ulanov, A. Tsvetkova, A. Lysenko, A. Kozlova, and T. Cline on behalf of the Konus-Wind team, report:
  The long-duration GRB 191004B (Swift-BAT detection: Cenko et al., GCN circ. 25947; Stamatikos et al., GCN circ. 25955) triggered Konus-Wind at T0=77626.99 s UT (21:33:46.990).
  The burst light curve shows a multi-peaked structure which starts at ~T0-0.5 s and has a total duration of ~5.5 s. The emission is seen up to ~1 MeV.
  The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB191004_T77626/
  As observed by Konus-Wind, the burst had a fluence of 4.13(-0.40,+0.45)x10^-6 erg/cm2, and a 64-ms peak flux, measured from T0+3.504 s, of 2.56(-0.73,+0.74)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
  The time-averaged spectrum of the burst (measured from T0 to T0+8.448 s) is best fit in the 20 keV - 10 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.51(-0.30,+0.34) and Ep = 172(-21,+27) keV (chi2 = 59/57 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -3.0 (chi2 = 59/56 dof).
  Assuming the redshift z=1.260 (D'Elia et al., GCN circ. 25956) and a standard cosmology model with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315, and Omega_Lambda = 0.685 (Planck Collaboration, 2014), we estimate the following rest-frame parameters: the isotropic energy release E_iso is 1.79(-0.17,+0.20)x10^52 erg, the peak luminosity L_iso is 2.51(-0.72,+0.73)x10^52 erg/s, and the rest-frame peak energy of the time-integrated spectrum, Ep,i, is 389(-47,+61) keV. With these energetics, the burst lies within the 90% prediction bands for both 'Amati' and 'Yonetoku' relations built for the sample of 138 long KW GRBs with known redshifts (Tsvetkova et al., ApJ 850 161, 2017).
  All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.
• GCN Circular #25976
  D. Svinkin reports on behalf of the Konus-Wind team:
  The redshift of GRB 191004B mentioned in GCN 25974 was incorrect, the correct one is z = 3.503 (D'Elia et al., GCN circ. 25956).
  Thus, assuming the redshift z=3.503 and a standard cosmology model with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315, and Omega_Lambda = 0.685 (Planck Collaboration, 2014), we estimate the following rest-frame parameters: the isotropic energy release E_iso is 1.08(-0.10,+0.12)x10^53 erg, the peak luminosity L_iso is 3.01(-0.86,+0.87)x10^53 erg/s, and the rest-frame peak energy of the time-integrated spectrum, Ep,i, is 775(-95,+122) keV. With these energetics, the burst lies within the 68% prediction bands for both 'Amati' and 'Yonetoku' relations built for the sample of 138 long KW GRBs with known redshifts (Tsvetkova et al., ApJ 850 161, 2017).
  I apologize for possible inconvenience.
• GCN Circular #25977
  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 obtained a second epoch (first epoch, GCN 25949) of Swift GRB 191004B (Palmer et al., GCN 25947) data with the LCO 1-m Sinistro instrument at the Sutherland Site (SAAO) on September 5, from 2:40 to 3:03 UT (corresponding to 4.95 to 5.3 hours from the GRB trigger time) with the Bessel R and I filters.
  We performed a series of 5x240s exposures, and we detect the afterglow with the following magnitudes:

  R = 21.01 +/- 0.08
  I = 19.91 +/- 0.08
  

  This flux is calibrated against several USNO-B1.0 objects near the GRB location but is not corrected for Galactic Extinction.
  These observations were possible thanks to the USVI NASA-EPSCoR Research Infrastructure Development (RID) grant NNX16AL44A.
• GCN Circular #25978
  GRB 191004B: Swift/UVOT Detection
  S. J. LaPorte (PSU) and S. B. Cenko (GSFC) report on behalf of the Swift/UVOT team:
  The Swift/UVOT began settled observations of the field of GRB 191004B 69 s after the BAT trigger (Cenko et al., GCN Circ. 25947). A fading source consistent with the XRT position (Beardmore et al. GCN Circ. 25951) is detected in the initial UVOT exposures.
  The preliminary UVOT position is:

      RA  (J2000) =  03:16:49.10 =  49.20459 (deg.)
      Dec (J2000) = -39:38:03.9  = -39.63441 (deg.)
  

  with an estimated uncertainty of 0.43 arc sec. (radius, 90% confidence), consistent with the positions reported by LCO (Strausbaugh et al. GCN Circ. 25949), NOT (Heintz et al. GCN Circ. 25954), VLT/X-Shooter (D'Elia et al. GCN Circ. 25956), COATLI (Watson et al. GCN Circ. 25958), and GROND (Schady et al. GCN Circ. 25960).
  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
  
  b                    38697         38997          295           >20.42
  uvm2             44827         45727          885           >20.25
  u                       294              387            91           >19.04
  
  v                    43916         44822          885           >20.07
  uvw1             45734         46281          538            >19.96
  uvw2             39915         40544          618            >20.09
  white                   82             232          147
  18.01+-0.05
  white             39003         39909          885              20.51+-0.13
  

  The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.02 in the direction of the burst (Schlegel et al. 1998).