  We report the discovery of a narrow-line QSO (NLQSO) RX J1334.2+3759 with a
steep soft X-ray spectrum. Soft X-ray emission from the NLQSO is highly
variable. Changes in the intensity by a factor of about 2 have been detected in
the ROSAT PSPC observations of RX J1334.2+3759 on time scales of 20000-40000s.
Rapid variability events have also been observed from RX J1334.2+3759. The most
extreme variable event has Delta L/Delta t = (1.95+/-1.02)E42 erg/s/s
corresponding to a change in intensity by a factor of about 4 within 400s. The
PSPC spectra of the NLQSO can be well represented by a power-law of photon
index 3.8, modified by an absorbing column local to the source over and above
that due to our own Galaxy. The intrinsic soft X-ray luminosity of RX
J1334.2+3759 is estimated to be 2.2E44 erg/s in the energy band of 0.1-2.0 keV.
The optical spectrum of RX J1334.2+3759 is typical of the NLS1 galaxies showing
strong Balmer Hbeta, Halpha, and forbidden line [O III]5007. Fe II multiplets,
usually present in the optical spectra of NLS1 galaxies, are also detected from
RX J1334.2+3759. Decomposition of the Hbeta and Halpha line profiles shows the
presence of narrow (FWHM = 880 km/s) and broad (FWHM = 2850 km/s) components in
the spectrum of RX J1334.2+3759. The narrow-line region of RX J1334.2+3759
appears to be significantly different from those of normal Seyfert galaxies. A
possible explanation for the observed properties of the narrow line region and
the broad line region is suggested in terms of density enhancements.
