  The study of NLS1s using ASCA has many advantages. A representative sample
can be studied; to date, observations of more than 30 NLS1s have been made.
ASCA observations are conducted contiguously, so their X-ray variability
properties can be studied systematically. ASCA detectors have a broad band pass
and moderate energy resolution, properties which allow their complex X-ray
spectrum to be deconvolved. ASCA observations have revealed that a soft excess
extending up to 1 keV is frequently found in the X-ray spectra from NLS1s. The
hard X-ray photon index has been shown to be systematically steeper than in
Seyfert 1 galaxies with broad optical lines. NLS1s also exhibit larger
amplitude variability than broad-line Seyferts of similar hard X-ray
luminosity. On occasion, features in the soft X-ray band have been detected
that appear to be specific to NLS1s; ionized iron lines have also been
observed. These results have been fundamental for building our current picture
of the X-ray emission from NLS1s. Many of the properties can be explained if
the specific accretion rate is larger in NLS1s than in Seyfert 1 galaxies with
broad optical lines. NLS1s may exemplify an extreme state of an intrinsic
physical parameter and therefore their study may lead to an enhanced
understanding of AGN in general. This proceedings contribution has two parts.
First I describe and discuss some of the results obtained from a study of the
X-ray variability in NLS1s using ASCA data (Leighly 1999ab). Then, I discuss
the results from our HST observations of NLS1s that were first presented during
this meeting (Leighly & Halpern 2000).

Astrophysics