  We report on Konus-Wind (KW) and Mikhail Pavlinsky ART-XC telescope
observations and analysis of a nearby GRB 221009A, the brightest $\gamma$-ray
burst (GRB) detected by KW for $>$28 years of observations. The prompt, pulsed
phase of the burst emission lasts for $\sim 600$ s and is followed by a steady
power-law decay lasting for more than 25 ks. From the analysis of the KW and
ART-XC light curves and the KW spectral data we derive time-averaged spectral
peak energy of the burst $E_p\approx 2.6$ MeV, $E_p$ at the brightest emission
peak $\approx 3.0$ MeV, the total 20 keV--10 MeV energy fluence of
$\approx0.22$ erg cm$^{-2}$, and the peak energy flux in the same band of
$\approx 0.03$ erg cm$^{-2}$ s$^{-1}$. The enormous observed fluence and peak
flux imply, at redshift $z=0.151$, huge values of isotropic energy release
$E_{\mathrm{iso}}\approx1.2\times10^{55}$ erg (or $\gtrsim 6.5$ solar rest
mass) and isotropic peak luminosity $L_{\mathrm{iso}}\approx3.4\times10^{54}$
erg s$^{-1}$ (64 ms scale), making GRB 221009A the most energetic and one the
most luminous bursts observed since the beginning of the GRB cosmological era
in 1997. The isotropic energetics of the burst fit nicely both "Amati" and
"Yonetoku" hardness-intensity correlations for $>$300 KW long GRBs, implying
that GRB~221009A is most likely a very hard, super-energetic version of a
"normal" long GRB.
