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TITLE:   GCN CIRCULAR
NUMBER:  29795
SUBJECT: GRB 210411D: Fermi GBM Final Real-time Localization
DATE:    21/04/11 16:41:35 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM  <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 16:31:10 UT on 11 Apr 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210411D (trigger 639851475.876502 / 210411688).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 358.5, Dec = 24.3 (J2000 degrees, equivalent to J2000 23h 53m, 24d 18'), with a statistical uncertainty of 3.6 degrees.

The angle from the Fermi LAT boresight is 55.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210411688/quicklook/glg_skymap_all_bn210411688.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/bn210411688/quicklook/glg_healpix_all_bn210411688.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210411688/quicklook/glg_lc_medres34_bn210411688.gif

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TITLE:   GCN CIRCULAR
NUMBER:  29796
SUBJECT: GRB 210411D: BALROG localization (Fermi Trigger 639851475 / GRB 210411688)
DATE:    21/04/11 16:59:18 GMT
FROM:    Jochen Greiner at MPI  <jcg@mpe.mpg.de>

F. Kunzweiler, B. Biltzinger, F. Berlato, J. Burgess & J. Greiner (all MPE Garching) report:

The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger
 at 16:31:10 on 11 Apr. 2021 were automatically fitted for spectrum
and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427;
Berlato et al. 2019, ApJ 873, 60).

The best-fit position (1 sigma statistical errors) is:
RA(2000.0) = 340.7+/-4.8 deg
Decl.(2000.0) = 36.6+/-3.2 deg
We estimate an additional systematic error of 2 deg.

Further details are available at:
https://grb.mpe.mpg.de/grb/GRB210411688/

The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB210411688/healpix

The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB210411688/json