We present results from spectral analysis of ASCA data on the strong Fe ii narrow-line Seyfert 1 galaxy Mrk 507 .
This galaxy was found to have an exceptionally flat ROSAT spectrum among the narrow-line Seyfert 1 galaxies ( NLS1s ) studied by Boller , Brandt & Fink ( 1996 ) .
The ASCA spectrum however shows a clear absorption feature in the energy band below 2 keV , which partly accounts for the flat spectrum observed with the ROSAT PSPC .
Such absorption is rarely observed in other NLS1s .
The absorption is mainly due to cold ( neutral or slightly ionized ) gas with a column density of ( 2–3 ) \times 10 ^ { 21 } cm ^ { -2 } .
A reanalysis of the PSPC data shows that an extrapolation of the best-fit model for the ASCA spectrum underpredicts the X-ray emission observed with the PSPC below 0.4 keV if the absorber is neutral , which indicates that the absorber is slightly ionized , covers only part of the central source , or there is extra soft thermal emission from an extended region .
There is also evidence that the X-ray absorption is complex ; an additional edge feature marginally detected at 0.84 keV suggests the presence of an additional high ionization absorber which imposes a strong O viii edge on the spectrum .
After correction for the absorption , the photon index of the intrinsic continuum , \Gamma \simeq 1.8 , obtained from the ASCA data is quite similar to that of ordinary Seyfert 1 galaxies .
Mrk 507 still has one of the flattest continuum slopes among NLS1 , but is no longer exceptional .
The strong optical Fe ii emission remains unusual in the light of the correlation between Fe ii strengths and steepness of soft X-ray slope .