Revisiting Emission-line Measurement Methods for Narrow-line Active Galactic Nuclei

Measuring broad emission-line widths in active galactic nuclei (AGN) is not straightforward owing to the complex nature of flux variability these systems. Line-width measurements become especially challenging when signal-to-noise low, profiles are narrower, or spectral resolution low. We conducted an extensive correlation analysis between from optical spectra Markarian 142 (Mrk 142; a narrow-line Seyfert galaxy) taken with Gemini North Telescope (Gemini) at 185.6+\-10.2 km/s and Lijiang (LJT) 695.2+\-3.9 investigate disparities measured broad-line both telescope data. Mrk~142 posed challenge due its narrow profiles, which were severely affected by instrumental broadening lower-resolution LJT spectra. discovered that allowing permitted lines having components vary during fitting caused leak component, resulting broader Fixing ratios constrained yielded Hydrogen-beta $\sim$54\% closer than flexible ratios. The availability different resolutions presented this unique opportunity inspect how our data adopt method accurately measure widths. Reconsidering line-measurement methods while studying diverse AGN populations critical for success future reverberation-mapping studies. Based on technique used work, we offer recommendations measuring line AGN.