Narrow Line Sy 1s

NLS1 NLS1 (Narrow-Line Seyfert 1, S1n) – Seyfert 1 with narrow lines. Defined by Osterbrock & Pogge (1985) as soft X-ray sources, having relatively narrow (∼2000 km/s) permitted lines only slightly broader than the forbidden ones. Various FeI, FeII, and FeIII emission lines are present, as well as often strong [FeVII] and [FeX] lines with higher ionization, unlike what is seen in Seyfert 2s. The ratio [OIII]5007/Hβ < 3, but exceptions are allowed if there are also strong [FeVII] and [FeX] emission lines present. FWHM(Hβ) < 2000km/s (Goodrich, 1989, 1995).	NLS1.0 NLS1.0 (Narrow-Line Seyfert 1.0) – Seyfert 1.0 with narrow lines. Defined by Osterbrock & Pogge (1985) as soft X-ray sources, having relatively narrow (∼2000 km/s) permitted lines only slightly broader than the forbidden ones. Various FeI, FeII, and FeIII emission lines are present, as well as often strong [FeVII] and [FeX] lines with higher ionization, unlike what is seen in Seyfert 2s. The ratio [OIII]5007/Hβ < 3, but exceptions are allowed if there are also strong [FeVII] and [FeX] emission lines present. FWHM(Hβ) < 2000km/s (Goodrich, 1989).
NLS1.2 NLS1.2 (Narrow-Line Seyfert 1.2) – Seyfert 1.2 with narrow lines. They are defined as soft X-ray sources; the resolved lines are relatively narrow (∼2000 km/s) and they have widths that are only slightly broader than the forbidden lines. FeI, FeII, and FeIII appear and often strong lines with higher ionization [FeVII] and [FeX] often, along with various emission lines (Osterbrock & Pogge, 1985).	NLS1.5 NLS1.5 (Narrow-Line Seyfert 1.5) – Seyfert 1.5 with narrow lines. They are defined as soft X-ray sources and the permitted broad lines are relatively narrow (∼2000 km/s) with widths only slightly exceeding those of the forbidden lines. FeI, FeII, FeIII appear and often strong lines with higher ionization [FeVII] and [FeX] often, along with various emission lines (Osterbrock & Pogge, 1985).
NLS1.8 NLS1.8 (Narrow-line Seyfert 1.8) – these are soft X-ray sources having narrow permitted lines only slightly broader than the forbidden ones; many FeI, FeII, FeIII, and often strong [FeVII] and [FeX] emission lines present. Only Hα and Hβ permitted broad components are observed, the same criterion as for S1.8 subtype (Osterbrock, 1981).	NLS1.9 NLS1.9 (Narrow-line Seyfert 1.9) – these are soft X-ray sources having narrow permitted lines only slightly broader than the forbidden ones; many FeI, FeII, FeIII, and often strong [FeVII] and [FeX] emission lines present. Only Hα permitted broad components is observed, the same criterion as for S1.9 subtype (Osterbrock, 1981).