Gamma-ray Burst 210323B

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN NOTICE
  

  TITLE:           GCN/FERMI NOTICE
  NOTICE_DATE:     Tue 23 Mar 21 12:03:57 UT
  NOTICE_TYPE:     Fermi-GBM Flight Position
  RECORD_NUM:      45
  TRIGGER_NUM:     638193818
  GRB_RA:           82.767d {+05h 31m 04s} (J2000),
                    82.959d {+05h 31m 50s} (current),
                    82.315d {+05h 29m 16s} (1950)
  GRB_DEC:         -34.317d {-34d 19' 00"} (J2000),
                   -34.302d {-34d 18' 06"} (current),
                   -34.353d {-34d 21' 09"} (1950)
  GRB_ERROR:       50.00 [deg radius, statistical plus systematic]
  GRB_INTEN:       0 [cnts/sec]
  DATA_SIGNIF:     5.50 [sigma]
  INTEG_TIME:      4.096 [sec]
  GRB_DATE:        19296 TJD;    82 DOY;   21/03/23
  GRB_TIME:        43413.09 SOD {12:03:33.09} UT
  GRB_PHI:         240.00 [deg]
  GRB_THETA:       170.00 [deg]
  DATA_TIME_SCALE: 4.0960 [sec]
  HARD_RATIO:      0.00
  LOC_ALGORITHM:   3 (version number of)
  MOST_LIKELY:     100%  Below horizon
  2nd_MOST_LIKELY:   0%  n/a
  DETECTORS:       0,0,0, 1,0,0, 1,0,0, 1,0,0, 0,0,
  SUN_POSTN:         2.83d {+00h 11m 19s}   +1.23d {+01d 13' 31"}
  SUN_DIST:         82.56 [deg]   Sun_angle= -5.3 [hr] (East of Sun)
  MOON_POSTN:      117.23d {+07h 48m 54s}  +24.50d {+24d 30' 04"}
  MOON_DIST:        67.20 [deg]
  MOON_ILLUM:      69 [%]
  GAL_COORDS:      238.58,-30.64 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:       78.85,-57.48 [deg] ecliptic lon,lat of the burst (or transient)
  LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210323502/quicklook/glg_lc_medres34_bn210323502.gif
  COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
  COMMENTS:        This trigger occurred at longitude,latitude = 249.07,-24.38 [deg].  
  COMMENTS:        WARNING: This Notice was received with a negative intensity field -- INTEN was set to 0.  
  COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.  
  

• GCN NOTICE
  

  TITLE:           GCN/FERMI NOTICE
  NOTICE_DATE:     Tue 23 Mar 21 13:55:34 UT
  NOTICE_TYPE:     Fermi-GBM Final Position
  RECORD_NUM:      0
  TRIGGER_NUM:     638193818
  GRB_RA:          253.080d {+16h 52m 19s} (J2000),
                   253.336d {+16h 53m 21s} (current),
                   252.476d {+16h 49m 54s} (1950)
  GRB_DEC:          +7.820d {+07d 49' 12"} (J2000),
                    +7.786d {+07d 47' 09"} (current),
                    +7.902d {+07d 54' 09"} (1950)
  GRB_ERROR:       3.84 [deg radius, statistical only]
  GRB_DATE:        19296 TJD;    82 DOY;   21/03/23
  GRB_TIME:        43413.09 SOD {12:03:33.09} UT
  GRB_PHI:         245.87 [deg]
  GRB_THETA:        18.01 [deg]
  E_RANGE:         50.000 - 300.000 [keV]
  LOC_ALGORITHM:   415 (Gnd S/W Version number)
  SUN_POSTN:         2.90d {+00h 11m 36s}   +1.26d {+01d 15' 21"}
  SUN_DIST:        109.19 [deg]   Sun_angle= 7.3 [hr] (West of Sun)
  MOON_POSTN:      118.31d {+07h 53m 15s}  +24.38d {+24d 22' 48"}
  MOON_DIST:       125.62 [deg]
  MOON_ILLUM:      69 [%]
  GAL_COORDS:       26.08, 30.00 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      250.53, 30.12 [deg] ecliptic lon,lat of the burst (or transient)
  LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210323502/quicklook/glg_lc_medres34_bn210323502.gif
  LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210323502/quicklook/glg_locplot_all_bn210323502.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 has human-in-the-loop processing.  
  

• GCN Circular #29701
  James DeLaunay (PSU), Aaron Tohuvavohu (U Toronto), Jamie Kennea (PSU) report:
  Swift/BAT did not trigger on GRB 210323B (T0: 2021-03-23 12:03:33 UTC, Fermi/GBM TRIGGER 638193818).
  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 best fit duration of ~8 seconds. With a maximum likelihood analysis (DeLaunay et al. 2021, in prep.) on the event-mode data we detect a location for the burst with a square root of the test statistic, sqrt(TS), of 11.77. The sqrt(TS) behaves similarly to SNR.
  This is a low significance detection and it could not be recovered using the normal BAT imaging technique, so there is a chance that this localization may be incorrect.
  The BAT position is RA, Dec = 259.664, +15.677 deg which is

    RA(J2000)  = 17h 18m 39.36s
    Dec(J2000) =  +15d 40' 37.20"
  

  with an estimated uncertainty of 6 arcmin.
  The partial coding was 10.6%
  This position is consistent with the Fermi GBM localization.
  XRT and UVOT follow-up has been requested. Results of follow-up observations will be reported in future circulars.
  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 #29714
  P. A. Evans (U. Leicester) reports on behalf of the Swift team:
  Swift has initiated a ToO observation of the Swift/BAT GRB 210323B. Automated analysis of the XRT data will be presented online at https://www.swift.ac.uk/ToO_GRBs/00021426
  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 #29908
  M. Perri (SSDC & INAF-OAR), V. D'Elia (SSDC & INAF-OAR), 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) 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-GUANO-detected burst GRB 210323B (James DeLaunay et al. GCN Circ. 29701), collecting 10.2 ks of Photon Counting (PC) mode data between T0+100.8 ks and T0+1300 ks.
  One uncatalogued X-ray source has been detected consistent with being within the Swift/BAT localization, it is below the RASS limit and shows no definitive signs of fading. Therefore, at the present time we cannot confirm this as the afterglow. Details of this source are given below:
  Source 1:

    RA (J2000.0):  259.6867  =  17:18:44.80
    Dec (J2000.0): +15.6339  =  +15:38:02.2
    Error: 4.6 arcsec (radius, 90% conf.)
    Count-rate: (1.18 [+0.71, -0.52])e-3 ct s^-1	 
    Distance: 173 arcsec from Swift/BAT position.
  

  Seven uncatalogued sources were also detected too far from the GRB position to be likely afterglow candidates.
  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/00021426.
  This circular is an official product of the Swift-XRT team.
• GCN Circular #30241
  E. Bissaldi (Politecnico and INFN Bari) and C. Meegan (UAH) report on behalf of the Fermi GBM Team:
  "At 12:03:33.09 UT on 23 March 2021, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 210323B (trigger 638193818/ 210323502), which was also detected by the Swift/BAT-GUANO (DeLaunay et al. 2021, GCN 29701). The Fermi GBM Final Real-time Localization is consistent with the Swift position.
  The angle from the Fermi LAT boresight at the GBM trigger time is 10 degrees.
  The GBM light curve consists of a weak emission episode with a duration (T90) of about 14 s (50-300 keV). The time-averaged spectrum from T0-4.9 s to T0+5.9 s is adequately fit by a power law function with an exponential high-energy cutoff. The power law index is -0.94 +/- 0.26 and the cutoff energy, parameterized as Epeak, is 740 +/- 540 keV.
  The event fluence (10-1000 keV) in this time interval is (2.1 +/- 0.3)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0-4.5 s in the 10-1000 keV band is 1.1 +/- 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/"