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TITLE:   GCN CIRCULAR
NUMBER:  27379
SUBJECT: GRB 200313B: Fermi GBM Final Real-time Localization
DATE:    20/03/13 11:07:35 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 SHORT GRB

At 10:57:12 UT on 13 Mar 2020, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 200313B (trigger 605789837.130132 / 200313456).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 202.2, Dec = 40.5 (J2000 degrees, equivalent to J2000 13h 28m, 40d 30'), with a statistical uncertainty of 5.3 degrees.

The angle from the Fermi LAT boresight is 96.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200313456/quicklook/glg_skymap_all_bn200313456.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200313456/quicklook/glg_healpix_all_bn200313456.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200313456/quicklook/glg_lc_medres34_bn200313456.gif

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TITLE:   GCN CIRCULAR
NUMBER:  27386
SUBJECT: IPN triangulation of GRB 200313B (short)
DATE:    20/03/15 17:21:19 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Ridnaia,
and T. Cline on behalf of the Konus-Wind team,

K. Hurley, on behalf of the IPN, and

A. Goldstein, M. S. Briggs, and C. Wilson-Hodge
on behalf of the Fermi GBM team, report:

The short-duration GRB 200313B
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 27379)
has been detected by Fermi (GBM trigger 605789837) and Konus-Wind, so 
far, at about 39432 s UT (10:57:12).

We have triangulated it to a Konus-GBM annulus centered at
RA(2000)=154.610 deg (10h 18m 26s) Dec(2000)=+8.761 deg (+8d 45' 41"),
whose radius is 60.602 +/- 2.419 deg (3 sigma).

The IPN localization is consistent with, but reduces the area of, the
Fermi-GBM one.

This localization may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB200313_T39435/IPN/

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TITLE:   GCN CIRCULAR
NUMBER:  27407
SUBJECT: Konus-Wind observation of GRB 200313B
DATE:    20/03/18 13:30:13 GMT
FROM:    Anna Ridnaia at Ioffe Institute  <ridnaia@mail.ioffe.ru>

A. Ridnaia, S. Golenetskii, R. Aptekar, D. Frederiks,
M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline
on behalf of the Konus-Wind team, report:

The short-duration GRB 200313B
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 27379;
IPN triangulation: Svinkin et al., GCN Circ. 27386)
triggered Konus-Wind at T0=39435.021 s UT (10:57:15.021).

The burst light curve shows a single pulse
which starts at ~T0-0.5 s and has a total duration of ~1.4 s.
The emission is seen up to ~1 MeV.

As observed by Konus-Wind, the burst
had a fluence of 6.83(-2.07,+3.49)x10^-7 erg/cm2,
and a 16-ms peak flux, measured from T0-0.016 s,
of 1.90(-1.18,+1.53)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+0.256 s)
is best fit in the 20 keV - 1 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.71(-0.91,+1.65)
and Ep = 145(-55,+252) keV (chi2 = 31/26 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -1.8
(chi2 = 31/25 dof).

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB200313_T39435/

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.