Gamma-ray Burst 210725B

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN/BACODINE POSITION NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Sun 25 Jul 21 12:01:33 UT
  NOTICE_TYPE:     Swift-BAT GRB Position
  TRIGGER_NUM:     1061554,   Seg_Num: 0
  GRB_RA:          192.932d {+12h 51m 44s} (J2000),
                   193.200d {+12h 52m 48s} (current),
                   192.310d {+12h 49m 15s} (1950)
  GRB_DEC:         +17.125d {+17d 07' 30"} (J2000),
                   +17.008d {+17d 00' 29"} (current),
                   +17.397d {+17d 23' 48"} (1950)
  GRB_ERROR:       3.00 [arcmin radius, statistical only]
  GRB_INTEN:       6442 [cnts]    Image_Peak=227 [image_cnts]
  TRIGGER_DUR:     3.072 [sec] 
  TRIGGER_INDEX:   474     E_range: 25-100 keV
  BKG_INTEN:       58104 [cnts]
  BKG_TIME:        43204.56 SOD {12:00:04.56} UT
  BKG_DUR:         32 [sec]
  GRB_DATE:        19420 TJD;   206 DOY;   21/07/25
  GRB_TIME:        43248.02 SOD {12:00:48.02} UT
  GRB_PHI:         147.32 [deg]
  GRB_THETA:        11.43 [deg]
  SOLN_STATUS:     0x2003
  RATE_SIGNIF:     11.00 [sigma]
  IMAGE_SIGNIF:    7.81 [sigma]
  MERIT_PARAMS:     +1  +0  +0  +2  +2  -2  +0  +0 -44  +0 
  SUN_POSTN:       125.06d {+08h 20m 14s}  +19.54d {+19d 32' 12"}
  SUN_DIST:         64.32 [deg]   Sun_angle= -4.5 [hr] (East of Sun)
  MOON_POSTN:      325.11d {+21h 40m 27s}  -19.04d {-19d 02' 37"}
  MOON_DIST:       134.37 [deg]
  MOON_ILLUM:      97 [%]
  GAL_COORDS:      303.33, 80.00 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      184.85, 20.81 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        SWIFT-BAT GRB Coordinates.  
  COMMENTS:        This is a rate trigger.  
  COMMENTS:        A point_source was found.  
  COMMENTS:        This does not match any source in the on-board catalog.  
  COMMENTS:        This does not match any source in the ground catalog.  
  COMMENTS:        There is a bright star (mag=6.32) 7.49 arcmin from this position.  
  COMMENTS:        This is a GRB.  
  COMMENTS:        This trigger occurred at longitude,latitude = 126.64,4.44 [deg].  
  

• red DSS finding chart ps-file
  
  
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Sun 25 Jul 21 12:02:25 UT
  NOTICE_TYPE:     Swift-XRT Nack-Position
  TRIGGER_NUM:     1061554,   Seg_Num: 0
  POINT_RA:        192.925d {+12h 51m 42s} (J2000)
  POINT_DEC:       +17.133d {+17d 07' 60"} (J2000)
  IMG_START_DATE:  19420 TJD;   206 DOY;   21/07/25
  IMG_START_TIME:  43338.87 SOD {12:02:18.87} UT,   90.9 [sec] since BAT Trigger Time
  COUNTS:          16    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:     Sun 25 Jul 21 12:18:03 UT
  NOTICE_TYPE:     Swift-BAT GRB Lightcurve
  TRIGGER_NUM:     1061554,   Seg_Num: 0
  GRB_RA:          192.932d {+12h 51m 44s} (J2000),
                   193.200d {+12h 52m 48s} (current),
                   192.310d {+12h 49m 15s} (1950)
  GRB_DEC:         +17.125d {+17d 07' 30"} (J2000),
                   +17.008d {+17d 00' 29"} (current),
                   +17.397d {+17d 23' 48"} (1950)
  GRB_DATE:        19420 TJD;   206 DOY;   21/07/25
  GRB_TIME:        43248.02 SOD {12:00:48.02} UT
  TRIGGER_INDEX:   474
  GRB_PHI:         147.32 [deg]
  GRB_THETA:        11.43 [deg]
  DELTA_TIME:      -27811.00 [sec]
  TRIGGER_DUR:     3.072 [sec] 
  SOLN_STATUS:     0x2003
  RATE_SIGNIF:     11.00 [sigma]
  IMAGE_SIGNIF:    7.81 [sigma]
  LC_URL:          sw01061554000msb.lc
  SUN_POSTN:       125.07d {+08h 20m 17s}  +19.53d {+19d 32' 03"}
  SUN_DIST:         64.31 [deg]   Sun_angle= -4.5 [hr] (East of Sun)
  MOON_POSTN:      325.27d {+21h 41m 05s}  -19.00d {-18d 59' 44"}
  MOON_DIST:       134.51 [deg]
  MOON_ILLUM:      97 [%]
  GAL_COORDS:      303.33, 80.00 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      184.85, 20.81 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        SWIFT-BAT GRB Lightcurve.  
  COMMENTS:           
  COMMENTS:        The next comments were copied from the BAT_POS Notice:  
  COMMENTS:        This is a rate trigger.  
  COMMENTS:        A point_source was found.  
  COMMENTS:        This does not match any source in the on-board catalog.  
  COMMENTS:        This does not match any source in the ground catalog.  
  COMMENTS:        There is a bright star (mag=6.32) 7.49 arcmin from this position.  
  COMMENTS:        This is a GRB.  
  COMMENTS:        This trigger occurred at longitude,latitude = 126.64,4.44 [deg].  
  COMMENTS:        The 3rd packet (of 3) was missing in the lightcurve data stream.  
  

  
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Sun 25 Jul 21 12:19:11 UT
  NOTICE_TYPE:     Swift-UVOT Source List
  TRIGGER_NUM:     1061554,   Seg_Num: 0
  POINT_RA:        192.925d {+12h 51m 42s} (J2000)
  POINT_DEC:       +17.133d {+17d 07' 60"} (J2000)
  POINT_ROLL:      283.822d
  IMG_START_DATE:  19420 TJD;   206 DOY;   21/07/25
  IMG_START_TIME:  43339.63 SOD {12:02:19.63} UT,   91.6 [sec] since BAT Trigger Time
  FILTER:          7, U
  BKG_MEAN:        0.798
  N_STARS:         16
  X_OFFSET:        143 [pixels]
  Y_OFFSET:        296 [pixels]
  X_MAX:           1582 [pixels]
  Y_MAX:           1735 [pixels]
  DET_THRESH:      8
  PHOTO_THRESH:    3
  SL_URL:          sw01061554000msufc0091.fits
  SUN_POSTN:       125.07d {+08h 20m 17s}  +19.53d {+19d 32' 02"}
  SUN_DIST:         64.30 [deg]   Sun_angle= -4.5 [hr] (East of Sun)
  MOON_POSTN:      325.28d {+21h 41m 08s}  -18.99d {-18d 59' 32"}
  MOON_DIST:       134.53 [deg]
  MOON_ILLUM:      97 [%]
  GAL_COORDS:      303.30, 80.00 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:      184.84, 20.81 [deg] ecliptic lon,lat of the pointing direction
  COMMENTS:        SWIFT-UVOT Source List.  
  

• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Sun 25 Jul 21 12:19:31 UT
  NOTICE_TYPE:     Swift-UVOT Image
  TRIGGER_NUM:     1061554,   Seg_Num: 0
  POINT_RA:        192.925d {+12h 51m 42s} (J2000)
  POINT_DEC:       +17.133d {+17d 07' 60"} (J2000)
  ROLL:            283.822d
  IMG_START_DATE:  19420 TJD;   206 DOY;   21/07/25
  IMG_START_TIME:  43339.63 SOD {12:02:19.63} UT,   91.6 [sec] since BAT Trigger Time
  FILTER:          7, U
  EXPOSURE_ID:     648907367
  X_OFFSET:        702 [pixels]
  Y_OFFSET:        855 [pixels]
  WIDTH:           160 [pixels]
  HEIGHT:          160 [pixels]
  X_GRB_POS:       862
  Y_GRB_POS:       1015
  BINNING_INDEX:   1
  IM_URL:          sw01061554000msuni0119.fits
  SUN_POSTN:       125.07d {+08h 20m 17s}  +19.53d {+19d 32' 02"}
  SUN_DIST:         64.30 [deg]   Sun_angle= -4.5 [hr] (East of Sun)
  MOON_POSTN:      325.29d {+21h 41m 09s}  -18.99d {-18d 59' 28"}
  MOON_DIST:       134.53 [deg]
  MOON_ILLUM:      97 [%]
  GAL_COORDS:      303.30, 80.00 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:      184.84, 20.81 [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:     Sun 25 Jul 21 12:20:13 UT
  NOTICE_TYPE:     Swift-UVOT Source List
  TRIGGER_NUM:     1061554,   Seg_Num: 0
  POINT_RA:        192.924d {+12h 51m 42s} (J2000)
  POINT_DEC:       +17.136d {+17d 08' 09"} (J2000)
  POINT_ROLL:      283.822d
  IMG_START_DATE:  19420 TJD;   206 DOY;   21/07/25
  IMG_START_TIME:  43594.81 SOD {12:06:34.81} UT,   346.8 [sec] since BAT Trigger Time
  FILTER:          9, B
  BKG_MEAN:        0.792
  N_STARS:         5
  X_OFFSET:        383 [pixels]
  Y_OFFSET:        536 [pixels]
  X_MAX:           1342 [pixels]
  Y_MAX:           1495 [pixels]
  DET_THRESH:      8
  PHOTO_THRESH:    3
  SL_URL:          sw01061554000msufc0346.fits
  SUN_POSTN:       125.07d {+08h 20m 17s}  +19.53d {+19d 32' 02"}
  SUN_DIST:         64.30 [deg]   Sun_angle= -4.5 [hr] (East of Sun)
  MOON_POSTN:      325.29d {+21h 41m 10s}  -18.99d {-18d 59' 21"}
  MOON_DIST:       134.54 [deg]
  MOON_ILLUM:      97 [%]
  GAL_COORDS:      303.29, 80.01 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:      184.84, 20.81 [deg] ecliptic lon,lat of the pointing direction
  COMMENTS:        SWIFT-UVOT Source List.  
  

• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Sun 25 Jul 21 12:19:39 UT
  NOTICE_TYPE:     Swift-UVOT Processed Image
  TRIGGER_NUM:     1061554,   Seg_Num: 0
  POINT_RA:        192.925d {+12h 51m 42s} (J2000)
  POINT_DEC:       +17.133d {+17d 07' 60"} (J2000)
  ROLL:            283.822d
  IMG_START_DATE:  19420 TJD;   206 DOY;   21/07/25
  IMG_START_TIME:  43339.63 SOD {12:02:19.63} UT,   91.6 [sec] since BAT Trigger Time
  FILTER:          7, U
  EXPOSURE_ID:     648907367
  X_OFFSET:        702 [pixels]
  Y_OFFSET:        855 [pixels]
  WIDTH:           160 [pixels]
  HEIGHT:          160 [pixels]
  X_GRB_POS:       862
  Y_GRB_POS:       1015
  BINNING_INDEX:   1
  IM_URL:          sw01061554000msuni0119.fits
  SUN_POSTN:       125.07d {+08h 20m 17s}  +19.53d {+19d 32' 02"}
  SUN_DIST:         64.30 [deg]   Sun_angle= -4.5 [hr] (East of Sun)
  MOON_POSTN:      325.29d {+21h 41m 09s}  -18.99d {-18d 59' 27"}
  MOON_DIST:       134.53 [deg]
  MOON_ILLUM:      97 [%]
  GAL_COORDS:      303.30, 80.00 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:      184.84, 20.81 [deg] ecliptic lon,lat of the pointing direction
  COMMENTS:        SWIFT-UVOT Processed Image.  
  COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
  COMMENTS:        The image has 2x2 binning (compression).  
  COMMENTS:        All 4 attachments are included.  
  

  
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Sun 25 Jul 21 12:20:30 UT
  NOTICE_TYPE:     Swift-UVOT Image
  TRIGGER_NUM:     1061554,   Seg_Num: 0
  POINT_RA:        192.924d {+12h 51m 42s} (J2000)
  POINT_DEC:       +17.136d {+17d 08' 09"} (J2000)
  ROLL:            283.822d
  IMG_START_DATE:  19420 TJD;   206 DOY;   21/07/25
  IMG_START_TIME:  43594.81 SOD {12:06:34.81} UT,   346.8 [sec] since BAT Trigger Time
  FILTER:          9, B
  EXPOSURE_ID:     648907622
  X_OFFSET:        702 [pixels]
  Y_OFFSET:        855 [pixels]
  WIDTH:           160 [pixels]
  HEIGHT:          160 [pixels]
  X_GRB_POS:       862
  Y_GRB_POS:       1015
  BINNING_INDEX:   1
  IM_URL:          sw01061554000msuni0374.fits
  SUN_POSTN:       125.07d {+08h 20m 17s}  +19.53d {+19d 32' 02"}
  SUN_DIST:         64.30 [deg]   Sun_angle= -4.5 [hr] (East of Sun)
  MOON_POSTN:      325.30d {+21h 41m 11s}  -18.99d {-18d 59' 18"}
  MOON_DIST:       134.54 [deg]
  MOON_ILLUM:      97 [%]
  GAL_COORDS:      303.29, 80.01 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:      184.84, 20.81 [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:     Sun 25 Jul 21 12:19:28 UT
  NOTICE_TYPE:     Swift-UVOT Processed Source List
  TRIGGER_NUM:     1061554,   Seg_Num: 0
  POINT_RA:        192.925d {+12h 51m 42s} (J2000)
  POINT_DEC:       +17.133d {+17d 07' 60"} (J2000)
  POINT_ROLL:      283.822d
  IMG_START_DATE:  19420 TJD;   206 DOY;   21/07/25
  IMG_START_TIME:  43339.63 SOD {12:02:19.63} UT,   91.6 [sec] since BAT Trigger Time
  FILTER:          7, U
  BKG_MEAN:        0.798
  N_STARS:         16
  X_OFFSET:        143 [pixels]
  Y_OFFSET:        296 [pixels]
  X_MAX:           1582 [pixels]
  Y_MAX:           1735 [pixels]
  DET_THRESH:      8
  PHOTO_THRESH:    3
  SL_URL:          sw01061554000msufc0091.fits
  SUN_POSTN:       125.07d {+08h 20m 17s}  +19.53d {+19d 32' 02"}
  SUN_DIST:         64.30 [deg]   Sun_angle= -4.5 [hr] (East of Sun)
  MOON_POSTN:      325.29d {+21h 41m 08s}  -18.99d {-18d 59' 29"}
  MOON_DIST:       134.53 [deg]
  MOON_ILLUM:      97 [%]
  GAL_COORDS:      303.30, 80.00 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:      184.84, 20.81 [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:     Sun 25 Jul 21 12:20:23 UT
  NOTICE_TYPE:     Swift-UVOT Processed Source List
  TRIGGER_NUM:     1061554,   Seg_Num: 0
  POINT_RA:        192.924d {+12h 51m 42s} (J2000)
  POINT_DEC:       +17.136d {+17d 08' 09"} (J2000)
  POINT_ROLL:      283.822d
  IMG_START_DATE:  19420 TJD;   206 DOY;   21/07/25
  IMG_START_TIME:  43594.81 SOD {12:06:34.81} UT,   346.8 [sec] since BAT Trigger Time
  FILTER:          9, B
  BKG_MEAN:        0.792
  N_STARS:         5
  X_OFFSET:        383 [pixels]
  Y_OFFSET:        536 [pixels]
  X_MAX:           1342 [pixels]
  Y_MAX:           1495 [pixels]
  DET_THRESH:      8
  PHOTO_THRESH:    3
  SL_URL:          sw01061554000msufc0346.fits
  SUN_POSTN:       125.07d {+08h 20m 17s}  +19.53d {+19d 32' 02"}
  SUN_DIST:         64.30 [deg]   Sun_angle= -4.5 [hr] (East of Sun)
  MOON_POSTN:      325.29d {+21h 41m 11s}  -18.99d {-18d 59' 19"}
  MOON_DIST:       134.54 [deg]
  MOON_ILLUM:      97 [%]
  GAL_COORDS:      303.29, 80.01 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:      184.84, 20.81 [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:     Sun 25 Jul 21 12:20:45 UT
  NOTICE_TYPE:     Swift-UVOT Processed Image
  TRIGGER_NUM:     1061554,   Seg_Num: 0
  POINT_RA:        192.924d {+12h 51m 42s} (J2000)
  POINT_DEC:       +17.136d {+17d 08' 09"} (J2000)
  ROLL:            283.822d
  IMG_START_DATE:  19420 TJD;   206 DOY;   21/07/25
  IMG_START_TIME:  43594.81 SOD {12:06:34.81} UT,   346.8 [sec] since BAT Trigger Time
  FILTER:          9, B
  EXPOSURE_ID:     648907622
  X_OFFSET:        702 [pixels]
  Y_OFFSET:        855 [pixels]
  WIDTH:           160 [pixels]
  HEIGHT:          160 [pixels]
  X_GRB_POS:       862
  Y_GRB_POS:       1015
  BINNING_INDEX:   1
  IM_URL:          sw01061554000msuni0374.fits
  SUN_POSTN:       125.07d {+08h 20m 17s}  +19.53d {+19d 32' 01"}
  SUN_DIST:         64.30 [deg]   Sun_angle= -4.5 [hr] (East of Sun)
  MOON_POSTN:      325.30d {+21h 41m 11s}  -18.99d {-18d 59' 15"}
  MOON_DIST:       134.55 [deg]
  MOON_ILLUM:      97 [%]
  GAL_COORDS:      303.29, 80.01 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:      184.84, 20.81 [deg] ecliptic lon,lat of the pointing direction
  COMMENTS:        SWIFT-UVOT Processed Image.  
  COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
  COMMENTS:        The image has 2x2 binning (compression).  
  COMMENTS:        All 4 attachments are included.  
  

  
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Sun 25 Jul 21 12:22:03 UT
  NOTICE_TYPE:     Swift-XRT Position
  TRIGGER_NUM:     1061554,   Seg_Num: 0
  GRB_RA:          192.9218d {+12h 51m 41.23s} (J2000),
                   193.1898d {+12h 52m 45.54s} (current),
                   192.3001d {+12h 49m 12.03s} (1950)
  GRB_DEC:         +17.1080d {+17d 06' 28.8"} (J2000),
                   +16.9911d {+16d 59' 27.7"} (current),
                   +17.3797d {+17d 22' 46.8"} (1950)
  GRB_ERROR:       1.9 [arcsec radius, statistical plus systematic, 90% containment]
  GRB_INTEN:       1.00e-10 [erg/cm2/sec]
  GRB_SIGNIF:      10.00 [sigma]
  IMG_START_DATE:  19420 TJD;   206 DOY;   21/07/25
  IMG_START_TIME:  43412.00 SOD {12:03:32.00} UT,   164.0 [sec] since BAT Trigger Time
  TAM[0-3]:        100.00 100.00 100.00 100.00
  AMPLIFIER:       1
  WAVEFORM:        31
  SUN_POSTN:       125.07d {+08h 20m 17s}  +19.53d {+19d 32' 01"}
  SUN_DIST:         64.30 [deg]   Sun_angle= -4.5 [hr] (East of Sun)
  MOON_POSTN:      325.31d {+21h 41m 14s}  -18.98d {-18d 59' 02"}
  MOON_DIST:       134.55 [deg]
  MOON_ILLUM:      97 [%]
  GAL_COORDS:      303.28, 79.98 [deg] galactic lon,lat of the burst
  ECL_COORDS:      184.85, 20.79 [deg] ecliptic lon,lat of the burst
  COMMENTS:        SWIFT-XRT Coordinates.  
  COMMENTS:        There is a bright star (mag=6.32) 7.70 arcmin from the XRT position.  
  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:        This position was enhanced using UVOT field astrometry.  
  COMMENTS:        The probability that this is a serendipitous source in the  
  COMMENTS:        SPER window is 1.1% < P(seren) < 2.8%.  
  

• GCN Circular #30508
  M. G. Bernardini (INAF-OAB), P. D'Avanzo (INAF-OAB), J. A. Kennea (PSU), N. J. Klingler (GSFC/UMBC/CRESSTII), F. E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), D. M. Palmer (LANL), T. Sakamoto (AGU) and T. Sbarrato (INAF-OAB) report on behalf of the Neil Gehrels Swift Observatory Team:
  At 12:00:48 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 210725B (trigger=1061554). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 192.932, +17.125 which is

     RA(J2000) = 12h 51m 44s
     Dec(J2000) = +17d 07' 30"
  

  with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The immediately-available BAT light curve (extending to T+8 seconds) shows a complex peak of at least 5 seconds duration. The peak count rate was ~1000 counts/sec (15-350 keV), at ~2 sec after the trigger.
  The XRT began observing the field at 12:02:18.8 UT, 90.9 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source with an enhanced position: RA, Dec 192.9219, 17.1080 which is equivalent to:

     RA(J2000)  = 12h 51m 41.26s
     Dec(J2000) = +17d 06' 28.9"
  

  with an uncertainty of 1.9 arcseconds (radius, 90% containment). This location is 70 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. No spectrum from the promptly downlinked event data is yet available to determine the column density.
  UVOT took a finding chart exposure of 250 seconds with the U filter starting 91 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.2 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18.0 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.023.
  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 #30510
  M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team.
  Using 273 s of XRT Photon Counting mode data and 1 UVOT images for GRB 210725B, 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 = 192.92217, +17.10809 which is equivalent to:

  RA (J2000): 12h 51m 41.32s
  Dec (J2000): +17d 06' 29.1"
  

  with an uncertainty of 2.5 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 #30512
  V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D.Kuvshinov, D. Cheryasov (Lomonosov Moscow State University, SAI, Physics Department),
  R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA),
  R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias),
  D. Buckley (South African Astronomical Observatory),
  O.A. Gres, N.M. Budnev, O.Ershova (Irkutsk State University, API),
  A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
  V. Yurkov, A. Gabovich, Yu. Sergienko (Blagoveschensk Educational State University)
  MASTER-Tavrida robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, SAI Crimea astronomical station) was pointed to the Swift GRB 210725B ( M. G. Bernardini et al., GCN 30508) errorbox 22581 sec after notice time and 22657 sec after trigger time at 2021-07-25 18:18:25 UT, with upper limit up to 16.5 mag. Observations started at twilight. The observations began at zenith distance = 56 deg. The sun altitude is -10.3 deg.
  The galactic latitude b = 80 deg., longitude l = 307 deg.
  Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1669944
  We obtain a following upper limits.

  Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
  _________|_____________________|_____|_______|______|________
  
     22747 |      MASTER-Tavrida |   C |   180 | 16.5 |        
  

  Filter C is a clear (unfiltred) band.
  The observation and reduction will continue. The message may be cited.
• GCN Circular #30516
  C. B. Markwardt (GSFC), 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), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
  Using the data set from T-239 to T+400 sec from the recent telemetry downlink, we report further analysis of BAT GRB 210725B (trigger #1061554) (Bernardini et al., GCN Circ. 30508). The BAT ground-calculated position is RA, Dec = 192.914, 17.130 deg which is

     RA(J2000)  =  12h 51m 39.3s
     Dec(J2000) = +17d 07' 48.5"
  

  with an uncertainty of 2.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 98%.
  The mask-weighted light curve shows a main pulse that starts at ~T0, peaks at ~T+1 s, and ends at ~T+5 s. In addition, there are some weak emission that starts at ~T-30 s and ends at ~T+15 s. T90 (15-350 keV) is 48.00 +- 22.63 sec (estimated error including systematics).
  The time-averaged spectrum from T-31.46 to T+16.54 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.16 +- 0.43. The fluence in the 15-150 keV band is 4.9 +- 1.1 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+0.97 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/1061554/BA/
• GCN Circular #30520
  V. D'Elia (SSDC & INAF-OAR), A. D'Ai (INAF-IASFPA), D.N. Burrows (PSU), J. D. Gropp (PSU), J.A. Kennea (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), A. Melandri (INAF-OAB) and M.G. Bernardini report on behalf of the Swift-XRT team:
  We have analysed 4.9 ks of XRT data for GRB 210725B (Bernardini et al. GCN Circ. 30508), from 94 s to 107.1 ks after the BAT trigger. The data comprise 68 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Goad et al. (GCN Circ. 30510).
  The light curve can be modelled with a power-law decay with a decay index of alpha=3.43 (+0.20, -0.18).
  A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.77 (+0.29, -0.27). The best-fitting absorption column is 6.6 (+2.7, -2.1) x 10^21 cm^-2, in excess of the Galactic value of 2.0 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.5 x 10^-11 (6.7 x 10^-11) erg cm^-2 count^-1.
  A summary of the WT-mode spectrum is thus:

  Total column:	     6.6 (+2.7, -2.1) x 10^21 cm^-2
  Galactic foreground: 2.0 x 10^20 cm^-2
  Excess significance: 5.2 sigma
  Photon index:	     1.77 (+0.29, -0.27)
  

  The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01061554.
  This circular is an official product of the Swift-XRT team.
• GCN Circular #30526
  M. H. Siegel (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 210725B 92 s after the BAT trigger (Bernardini et al., GCN Circ. 30508). No optical afterglow consistent with the XRT position (Goad et al. GCN Circ. 30510) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are:

  Filter         T_start(s)   T_stop(s)      Exp(s)         Mag
  
  u (fc)               92          341          246         >20.5
  b                  347          439           91         >20.0
  u                   92          341          246         >20.5
  w2                3722         3905          180         >19.4
  

  The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.023 in the direction of the burst (Schlegel et al. 1998).
• GCN Circular #30546
  C. Fletcher (USRA) reports on behalf of the Fermi-GBM Team:
  Swift-BAT detected GRB 210725B at 12:00:48 UT (GCN 30508). There was no Fermi-GBM onboard trigger around the event.
  An automated, blind search for short gamma-ray bursts below the onboard triggering threshold in Fermi-GBM identified a transient source at this time.
  The GBM targeted search [1], the most sensitive, coherent search for GRB-like signals identified a transient most significantly on the 8.192 s timescale, with a false alarm rate of 2.6e-05 Hz and a location consistent with the Swift-BAT event, using the standard search protocol with a S/N of 9. The GBM targeted search event was found with the highest significance with a "normal" spectrum (Band function with Epeak = 230 keV, alpha = -1.0, beta = -2.3) for a GRB.
  [1] Goldstein et al. 2019 arXiv:1903.12597