  We observed an extended X-ray source designated as Suzaku J1759-3450 with the
Suzaku and Chandra observations towards 1RXS J175911.0-344921, which is an
unidentified X-ray source listed in the ROSAT Bright Source Catalogue. A
conspicuous emission line at 6 keV was also found in the Suzaku J1759-3450
spectrum. Assuming the emission line to be K emission from He-like Fe ions, we
inferred Suzaku J1759-3450 to be an extragalactic object located at z = 0.13.
The radial profile of the surface brightness in the 0.5-10 keV band was
explained well with an isothermal beta-model of r_c = 1.61' and beta = 0.78.
The X-ray spectrum was well reproduced by an optically-thin thermal plasma with
the electron temperature of kT_e = 5.3 keV attenuated by the photoelectric
absorption of N_H = 2.3 x 10^21 cm^-2. The bolometric X-ray luminosity of L_X
(r < r_500) = 4.3 x 10^44 erg s^-1 is consistent with that expected from the
L_X-T relation of clusters of galaxies. In terms of the spatial extent, the
X-ray spectrum, and the bolometric luminosity of the X-ray emitting gas, we
concluded that Suzaku J1759-3450 is a new cluster of galaxies.
