Gamma-ray Burst 210605B

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN NOTICE
  

  TITLE:           GCN/FERMI NOTICE
  NOTICE_DATE:     Sat 05 Jun 21 14:56:22 UT
  NOTICE_TYPE:     Fermi-GBM Flight Position
  RECORD_NUM:      43
  TRIGGER_NUM:     644597763
  GRB_RA:           12.400d {+00h 49m 36s} (J2000),
                    12.668d {+00h 50m 40s} (current),
                    11.775d {+00h 47m 06s} (1950)
  GRB_DEC:         -14.700d {-14d 41' 59"} (J2000),
                   -14.584d {-14d 35' 00"} (current),
                   -14.972d {-14d 58' 19"} (1950)
  GRB_ERROR:       24.10 [deg radius, statistical plus systematic]
  GRB_INTEN:       51 [cnts/sec]
  DATA_SIGNIF:     6.00 [sigma]
  INTEG_TIME:      4.096 [sec]
  GRB_DATE:        19370 TJD;   156 DOY;   21/06/05
  GRB_TIME:        53758.08 SOD {14:55:58.08} UT
  GRB_PHI:         320.00 [deg]
  GRB_THETA:        15.00 [deg]
  DATA_TIME_SCALE: 4.0960 [sec]
  HARD_RATIO:      0.66
  LOC_ALGORITHM:   3 (version number of)
  MOST_LIKELY:      95%  GRB
  2nd_MOST_LIKELY:   3%  Generic Transient
  DETECTORS:       1,1,0, 0,0,0, 0,0,0, 0,0,0, 0,0,
  SUN_POSTN:        73.90d {+04h 55m 37s}  +22.61d {+22d 36' 40"}
  SUN_DIST:         70.54 [deg]   Sun_angle= 4.1 [hr] (West of Sun)
  MOON_POSTN:       22.40d {+01h 29m 37s}   +5.09d {+05d 05' 16"}
  MOON_DIST:        21.91 [deg]
  MOON_ILLUM:      20 [%]
  GAL_COORDS:      120.87,-77.56 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:        5.42,-18.39 [deg] ecliptic lon,lat of the burst (or transient)
  LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210605622/quicklook/glg_lc_medres34_bn210605622.gif
  COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
  COMMENTS:        This trigger occurred at longitude,latitude = 248.40,12.55 [deg].  
  COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
  

• GCN NOTICE
  

  TITLE:           GCN/FERMI NOTICE
  NOTICE_DATE:     Sat 05 Jun 21 14:56:38 UT
  NOTICE_TYPE:     Fermi-GBM Flight Position
  RECORD_NUM:      69
  TRIGGER_NUM:     644597763
  GRB_RA:           11.400d {+00h 45m 36s} (J2000),
                    11.672d {+00h 46m 41s} (current),
                    10.764d {+00h 43m 03s} (1950)
  GRB_DEC:          -5.217d {-05d 13' 00"} (J2000),
                    -5.100d {-05d 05' 58"} (current),
                    -5.490d {-05d 29' 23"} (1950)
  GRB_ERROR:       10.53 [deg radius, statistical plus systematic]
  GRB_INTEN:       127 [cnts/sec]
  DATA_SIGNIF:     13.20 [sigma]
  INTEG_TIME:      4.096 [sec]
  GRB_DATE:        19370 TJD;   156 DOY;   21/06/05
  GRB_TIME:        53758.08 SOD {14:55:58.08} UT
  GRB_PHI:           0.00 [deg]
  GRB_THETA:        15.00 [deg]
  DATA_TIME_SCALE: 4.0960 [sec]
  HARD_RATIO:      0.86
  LOC_ALGORITHM:   3 (version number of)
  MOST_LIKELY:      98%  GRB
  2nd_MOST_LIKELY:   1%  Generic Transient
  DETECTORS:       1,1,0, 0,0,0, 0,0,0, 0,0,0, 0,0,
  SUN_POSTN:        73.90d {+04h 55m 37s}  +22.61d {+22d 36' 40"}
  SUN_DIST:         66.78 [deg]   Sun_angle= 4.1 [hr] (West of Sun)
  MOON_POSTN:       22.41d {+01h 29m 37s}   +5.09d {+05d 05' 19"}
  MOON_DIST:        14.79 [deg]
  MOON_ILLUM:      20 [%]
  GAL_COORDS:      119.04,-68.04 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:        8.42, -9.31 [deg] ecliptic lon,lat of the burst (or transient)
  LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210605622/quicklook/glg_lc_medres34_bn210605622.gif
  COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
  COMMENTS:        This trigger occurred at longitude,latitude = 248.40,12.55 [deg].  
  COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
  

• GCN NOTICE
  

  TITLE:           GCN/FERMI NOTICE
  NOTICE_DATE:     Sat 05 Jun 21 14:56:31 UT
  NOTICE_TYPE:     Fermi-GBM Flight Position
  RECORD_NUM:      58
  TRIGGER_NUM:     644597763
  GRB_RA:           15.750d {+01h 03m 00s} (J2000),
                    16.023d {+01h 04m 06s} (current),
                    15.113d {+01h 00m 27s} (1950)
  GRB_DEC:          -2.767d {-02d 46' 00"} (J2000),
                    -2.652d {-02d 39' 06"} (current),
                    -3.035d {-03d 02' 05"} (1950)
  GRB_ERROR:       17.20 [deg radius, statistical plus systematic]
  GRB_INTEN:       111 [cnts/sec]
  DATA_SIGNIF:     8.40 [sigma]
  INTEG_TIME:      2.048 [sec]
  GRB_DATE:        19370 TJD;   156 DOY;   21/06/05
  GRB_TIME:        53758.08 SOD {14:55:58.08} UT
  GRB_PHI:           0.00 [deg]
  GRB_THETA:        20.00 [deg]
  DATA_TIME_SCALE: 2.0480 [sec]
  HARD_RATIO:      0.63
  LOC_ALGORITHM:   3 (version number of)
  MOST_LIKELY:      95%  GRB
  2nd_MOST_LIKELY:   3%  Generic Transient
  DETECTORS:       1,1,0, 0,0,0, 0,0,0, 0,0,0, 0,0,
  SUN_POSTN:        73.90d {+04h 55m 37s}  +22.61d {+22d 36' 40"}
  SUN_DIST:         61.80 [deg]   Sun_angle= 3.9 [hr] (West of Sun)
  MOON_POSTN:       22.40d {+01h 29m 37s}   +5.09d {+05d 05' 18"}
  MOON_DIST:        10.03 [deg]
  MOON_ILLUM:      20 [%]
  GAL_COORDS:      129.90,-65.48 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:       13.43, -8.75 [deg] ecliptic lon,lat of the burst (or transient)
  LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210605622/quicklook/glg_lc_medres34_bn210605622.gif
  COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
  COMMENTS:        This trigger occurred at longitude,latitude = 248.40,12.55 [deg].  
  COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
  

• GCN NOTICE
  

  TITLE:           GCN/FERMI NOTICE
  NOTICE_DATE:     Sat 05 Jun 21 14:56:41 UT
  NOTICE_TYPE:     Fermi-GBM Ground Position
  RECORD_NUM:      57
  TRIGGER_NUM:     644597763
  GRB_RA:           22.930d {+01h 31m 43s} (J2000),
                    23.195d {+01h 32m 47s} (current),
                    22.311d {+01h 29m 15s} (1950)
  GRB_DEC:         -11.450d {-11d 26' 59"} (J2000),
                   -11.340d {-11d 20' 24"} (current),
                   -11.707d {-11d 42' 24"} (1950)
  GRB_ERROR:       8.16 [deg radius, statistical only]
  DATA_SIGNIF:     6.30 [sigma]
  DATA_INTERVAL:   4.096 [sec]
  GRB_DATE:        19370 TJD;   156 DOY;   21/06/05
  GRB_TIME:        53758.08 SOD {14:55:58.08} UT
  GRB_PHI:         332.00 [deg]
  GRB_THETA:        25.00 [deg]
  E_RANGE:         44.032 - 279.965 [keV]
  LOC_ALGORITHM:   4173 (Gnd S/W Version number)
  SUN_POSTN:        73.90d {+04h 55m 37s}  +22.61d {+22d 36' 40"}
  SUN_DIST:         60.16 [deg]   Sun_angle= 3.4 [hr] (West of Sun)
  MOON_POSTN:       22.41d {+01h 29m 37s}   +5.09d {+05d 05' 20"}
  MOON_DIST:        16.45 [deg]
  MOON_ILLUM:      20 [%]
  GAL_COORDS:      155.99,-71.69 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:       16.73,-19.51 [deg] ecliptic lon,lat of the burst (or transient)
  LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210605622/quicklook/glg_lc_medres34_bn210605622.gif
  POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_644597763.fits
  COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
  COMMENTS:        In the LAT Field-of-view.  
  COMMENTS:        This Notice was ground-generated -- not flight-generated.  
  COMMENTS:        The LC_URL file will not be created/available until ~15 min after the trigger.  
  COMMENTS:        The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.  
  

• GCN NOTICE
  

  TITLE:           GCN/FERMI NOTICE
  NOTICE_DATE:     Sat 05 Jun 21 14:57:28 UT
  NOTICE_TYPE:     Fermi-GBM Ground Position
  RECORD_NUM:      0
  TRIGGER_NUM:     644597763
  GRB_RA:           22.140d {+01h 28m 34s} (J2000),
                    22.410d {+01h 29m 38s} (current),
                    21.510d {+01h 26m 02s} (1950)
  GRB_DEC:          -5.710d {-05d 42' 35"} (J2000),
                    -5.600d {-05d 35' 58"} (current),
                    -5.968d {-05d 58' 05"} (1950)
  GRB_ERROR:       5.64 [deg radius, statistical only]
  DATA_SIGNIF:     12.80 [sigma]
  DATA_INTERVAL:   11.264 [sec]
  GRB_DATE:        19370 TJD;   156 DOY;   21/06/05
  GRB_TIME:        53758.08 SOD {14:55:58.08} UT
  GRB_PHI:         346.00 [deg]
  GRB_THETA:        25.00 [deg]
  E_RANGE:         44.032 - 279.965 [keV]
  LOC_ALGORITHM:   41731 (Gnd S/W Version number)
  SUN_POSTN:        73.91d {+04h 55m 37s}  +22.61d {+22d 36' 40"}
  SUN_DIST:         57.69 [deg]   Sun_angle= 3.4 [hr] (West of Sun)
  MOON_POSTN:       22.41d {+01h 29m 39s}   +5.09d {+05d 05' 30"}
  MOON_DIST:        10.69 [deg]
  MOON_ILLUM:      20 [%]
  GAL_COORDS:      147.00,-66.83 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:       18.28,-13.91 [deg] ecliptic lon,lat of the burst (or transient)
  LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210605622/quicklook/glg_lc_medres34_bn210605622.gif
  POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_644597763.fits
  COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
  COMMENTS:        In the LAT Field-of-view.  
  COMMENTS:        This is likely a Long GRB.  
  COMMENTS:        This Notice was ground-generated -- not flight-generated.  
  COMMENTS:        The LC_URL file will not be created/available until ~15 min after the trigger.  
  COMMENTS:        The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.  
  

• GCN NOTICE
  

  TITLE:           GCN/FERMI NOTICE
  NOTICE_DATE:     Sat 05 Jun 21 14:57:38 UT
  NOTICE_TYPE:     Fermi-GBM Ground Position
  RECORD_NUM:      1
  TRIGGER_NUM:     644597763
  GRB_RA:           17.650d {+01h 10m 36s} (J2000),
                    17.919d {+01h 11m 41s} (current),
                    17.022d {+01h 08m 05s} (1950)
  GRB_DEC:          -8.410d {-08d 24' 35"} (J2000),
                    -8.296d {-08d 17' 46"} (current),
                    -8.676d {-08d 40' 32"} (1950)
  GRB_ERROR:       4.66 [deg radius, statistical only]
  DATA_SIGNIF:     16.60 [sigma]
  DATA_INTERVAL:   15.360 [sec]
  GRB_DATE:        19370 TJD;   156 DOY;   21/06/05
  GRB_TIME:        53758.08 SOD {14:55:58.08} UT
  GRB_PHI:         342.00 [deg]
  GRB_THETA:        20.00 [deg]
  E_RANGE:         44.032 - 279.965 [keV]
  LOC_ALGORITHM:   41731 (Gnd S/W Version number)
  SUN_POSTN:        73.91d {+04h 55m 37s}  +22.61d {+22d 36' 40"}
  SUN_DIST:         62.90 [deg]   Sun_angle= 3.7 [hr] (West of Sun)
  MOON_POSTN:       22.41d {+01h 29m 39s}   +5.09d {+05d 05' 32"}
  MOON_DIST:        14.12 [deg]
  MOON_ILLUM:      20 [%]
  GAL_COORDS:      137.44,-70.74 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:       12.96,-14.68 [deg] ecliptic lon,lat of the burst (or transient)
  LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210605622/quicklook/glg_lc_medres34_bn210605622.gif
  POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_644597763.fits
  COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
  COMMENTS:        In the LAT Field-of-view.  
  COMMENTS:        This is likely a Long GRB.  
  COMMENTS:        This Notice was ground-generated -- not flight-generated.  
  COMMENTS:        The LC_URL file will not be created/available until ~15 min after the trigger.  
  COMMENTS:        The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.  
  

• GCN NOTICE
  

  TITLE:           GCN/FERMI NOTICE
  NOTICE_DATE:     Sat 05 Jun 21 14:57:52 UT
  NOTICE_TYPE:     Fermi-GBM Ground Position
  RECORD_NUM:      2
  TRIGGER_NUM:     644597763
  GRB_RA:           16.520d {+01h 06m 05s} (J2000),
                    16.790d {+01h 07m 10s} (current),
                    15.890d {+01h 03m 34s} (1950)
  GRB_DEC:          -7.730d {-07d 43' 47"} (J2000),
                    -7.616d {-07d 36' 56"} (current),
                    -7.997d {-07d 59' 49"} (1950)
  GRB_ERROR:       3.50 [deg radius, statistical only]
  DATA_SIGNIF:     18.10 [sigma]
  DATA_INTERVAL:   19.456 [sec]
  GRB_DATE:        19370 TJD;   156 DOY;   21/06/05
  GRB_TIME:        53758.08 SOD {14:55:58.08} UT
  GRB_PHI:         345.00 [deg]
  GRB_THETA:        19.00 [deg]
  E_RANGE:         44.032 - 279.965 [keV]
  LOC_ALGORITHM:   41731 (Gnd S/W Version number)
  SUN_POSTN:        73.91d {+04h 55m 37s}  +22.61d {+22d 36' 40"}
  SUN_DIST:         63.52 [deg]   Sun_angle= 3.8 [hr] (West of Sun)
  MOON_POSTN:       22.41d {+01h 29m 39s}   +5.09d {+05d 05' 35"}
  MOON_DIST:        13.89 [deg]
  MOON_ILLUM:      20 [%]
  GAL_COORDS:      133.75,-70.29 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:       12.18,-13.62 [deg] ecliptic lon,lat of the burst (or transient)
  LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210605622/quicklook/glg_lc_medres34_bn210605622.gif
  POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_644597763.fits
  COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
  COMMENTS:        In the LAT Field-of-view.  
  COMMENTS:        This is likely a Long GRB.  
  COMMENTS:        This Notice was ground-generated -- not flight-generated.  
  COMMENTS:        The LC_URL file will not be created/available until ~15 min after the trigger.  
  COMMENTS:        The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.  
  

• GCN NOTICE
  

  TITLE:           GCN/FERMI NOTICE
  NOTICE_DATE:     Sat 05 Jun 21 15:05:21 UT
  NOTICE_TYPE:     Fermi-GBM Final Position
  RECORD_NUM:      0
  TRIGGER_NUM:     644597763
  GRB_RA:           15.120d {+01h 00m 29s} (J2000),
                    15.391d {+01h 01m 34s} (current),
                    14.488d {+00h 57m 57s} (1950)
  GRB_DEC:          -6.470d {-06d 28' 11"} (J2000),
                    -6.355d {-06d 21' 17"} (current),
                    -6.739d {-06d 44' 20"} (1950)
  GRB_ERROR:       3.82 [deg radius, statistical only]
  GRB_DATE:        19370 TJD;   156 DOY;   21/06/05
  GRB_TIME:        53758.08 SOD {14:55:58.08} UT
  GRB_PHI:         350.00 [deg]
  GRB_THETA:        18.00 [deg]
  E_RANGE:         44.032 - 279.965 [keV]
  LOC_ALGORITHM:   41731 (Gnd S/W Version number)
  SUN_POSTN:        73.91d {+04h 55m 39s}  +22.61d {+22d 36' 42"}
  SUN_DIST:         64.12 [deg]   Sun_angle= 3.9 [hr] (West of Sun)
  MOON_POSTN:       22.47d {+01h 29m 53s}   +5.12d {+05d 07' 10"}
  MOON_DIST:        13.48 [deg]
  MOON_ILLUM:      20 [%]
  GAL_COORDS:      129.28,-69.23 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:       11.37,-11.92 [deg] ecliptic lon,lat of the burst (or transient)
  LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210605622/quicklook/glg_lc_medres34_bn210605622.gif
  LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210605622/quicklook/glg_locplot_all_bn210605622.png
  COMMENTS:        Fermi-GBM Final Position.  
  COMMENTS:        This Notice was ground-generated -- not flight-generated.  
  COMMENTS:        The LC_URL file should be available by the time this FINAL notice is produced.  
  COMMENTS:        This notice was generated completely by automated pipeline processing.  
  COMMENTS:        In the LAT Field-of-view.  
  COMMENTS:        This is likely a Long GRB.  
  

• GCN Circular #30129
  The Fermi GBM team reports the detection of a likely LONG GRB
  At 14:55:58 UT on 5 Jun 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210605B (trigger 644597763.075646 / 210605622).
  The on-ground calculated location, using the Fermi GBM trigger data, is RA = 15.1, Dec = -6.5 (J2000 degrees, equivalent to J2000 01h 00m, -6d 30'), with a statistical uncertainty of 3.8 degrees.
  The angle from the Fermi LAT boresight is 18.0 degrees.
  The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210605622/quicklook/glg_skymap_all_bn210605622.png
  The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210605622/quicklook/glg_healpix_all_bn210605622.fit
  The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210605622/quicklook/glg_lc_medres34_bn210605622.gif
  
• GCN Circular #30130
  James DeLaunay (PSU), Aaron Tohuvavohu (U Toronto), Jamie A. Kennea (PSU), Gayathri Raman (PSU) report:
  Swift/BAT did not trigger on GRB 210605B (T0: 2021-06-06 14:55:58 UTC, Fermi/GBM GCN 31029).
  The Fermi/GBM notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1).
  Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground.
  The burst is detected in BAT with a duration of at least 20 seconds. The burst occurred during a Swift slew. The position of the burst was found with SNR of 8.4 using a novel slew image mosaicing procedure (DeLaunay et al. 2021, in prep.), and so the positional uncertainty is not yet well characterized.
  The BAT position is RA, Dec = 15.732, -6.467 deg which is

     RA(J2000)  = 01h 02m 55.68s
     Dec(J2000) =  -6d 28′ 1.2″
  

  with an estimated uncertainty of 5 arcmin.
  This position is consistent with the Ferm/GBM localization (GCN 31029).
  GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches.
  A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/
• GCN Circular #30133
  P. A. Evans (U. Leicester) reports on behalf of the Swift team:
  Swift has initiated a ToO observation of the Swift/BAT GRB 210605B. Automated analysis of the XRT data will be presented online at https://www.swift.ac.uk/ToO_GRBs/00021450
  Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. These are not necessarily related to the Swift/BAT event. Any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration.
  Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).
  This circular is an official product of the Swift-XRT team.
• GCN Circular #30146
  A. D'Ai (INAF-IASFPA), A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), D.N. Burrows (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A. Melandri (INAF-OAB), T. Sbarrato (INAF-OAB) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:
  Swift-XRT has performed follow-up observations of the Swift/BAT-detected burst GRB 210605B (James DeLaunay et al. GCN Circ. 30130), collecting 5.0 ks of Photon Counting (PC) mode data between T0+74.2 ks and T0+96.6 ks.
  One uncatalogued X-ray sources has been detected, however it is not above the RASS limit or shows definitive signs of fading. Therefore, at the present time we cannot confirm if this source is the afterglow. Details of the source are given below:
  Source 1:

    RA (J2000.0):  15.7456  =  01:02:58.95
    Dec (J2000.0): -6.4290  =  -06:25:44.3
    Error: 5.7 arcsec (radius, 90% conf.)
    Count-rate: (2.94 [+1.05, -0.86])e-3 ct s^-1	 
    Distance: 145 arcsec from Swift/BAT position.
    Flux: (9.3 [+3.3, -2.7])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)
  

  The field has been previously observed by XRT for the Swift Gravitational Wave Galaxy Survey (https://www.swift.ac.uk/SGWGS/). No source was detected at this position on a 5.3 ks integrated exposure, down to a 3-σ upper limit of 2.7 e-3 ct s^-1.
  A catalogued source and a spurious source caused by Earth limb contamination were also detected.
  The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/ToO_GRBs/00021450.
  This circular is an official product of the Swift-XRT team.
• GCN Circular #30209
  S. Poolakkil (UAH) and C. Meegan (UAH) report on behalf of the Fermi GBM Team:
  "At 14:55:58.08 UT on 5 June 2021, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 210605B (trigger 644597763 / 210605622) which was also detected by the Swift/BAT-GUANO (DeLaunay et al. 2021, GCN 30130) The Fermi GBM Final Real-time Localization (GCN 30129) is consistent with the Swift position.
  The angle from the Fermi LAT boresight at the GBM trigger time is 19 degrees.
  The GBM light curve consists of multiple peaks followed by some extended emission with a duration (T90) of about 110 s (50-300 keV). The time-averaged spectrum from T0-3.07 s to T0+113.66 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.78 +/- 0.08 and the cutoff energy, parameterized as Epeak, is 150 +/- 11 keV.
  The event fluence (10-1000 keV) in this time interval is (10.12 +/- 0.44)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+26.36 s in the 10-1000 keV band is 3.3 +/- 0.2 ph/s/cm^2.
  The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html
  For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"
• GCN Circular #30234
  A. D'Ai (INAF-IASFPA), A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), D.N. Burrows (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A. Melandri (INAF-OAB), T. Sbarrato (INAF-OAB) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:
  Swift-XRT has conducted further observations of the field of the Swift/BAT-GUANO detected burst GRB 210605B (James DeLaunay et al. GCN Circ. 30130). The observations now extend from T0+74.3 ks to T0+734.1 ks.
  Of the sources reported by D'Ai et al. (GCN Circ. 30146), "Source 1" is fading with 2.5 sigma significance and thus is believed to be the GRB afterglow. The position of this source is RA, Dec=15.7456, -6.4290 which is equivalent to:

  RA (J2000): 01:02:58.95
  Dec(J2000): -06:25:44.3
  

  with an uncertainty of 5.7 arcsec (radius, 90% confidence). This position is 2.4 arcmin from the Swift/BAT position.
  The light curve can be modelled with a power-law decay with a decay index of alpha=0.8 (+0.7, -0.4).
  The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00021450. The results of the full analysis of the XRT observations are available at https://www.swift.ac.uk/ToO_GRBs/00021450.
  This circular is an official product of the Swift-XRT team.