| Abstract : | Abstract: With the advent of large optical monitoring surveys such as Zwicky Transient Facility (ZTF) it has become possible to carry out long-term variability of a statistical sample of various types of AGNs. In this context, we made a sample of 5374 NLSy galaxies for which r-band and g-band light curves in the ZTF survey are present for a duration of about 5 years (~62 months). We used the variance method where the variance of observed magnitudes is used to study the flux variability in ‘r’ and g-band. We found that 50% of NLSY1 sources show variability with variability amplitude of more than 3% magnitude. We use the quasi-simultaneous light curve of 2687 NLSy1 with an epoch difference of 1 day, to quantify their color variability. For this, we used the least square polynomial fit of the straight line on temporal variation of the color index in conjunction with the flux variability. We found that out of the total 470 NLSy1 sources, the bluer-when-brighter (BWB) and redder-when-brighter (RWB) trend is shown by 24.2% and 75.8% of sources respectively. To compare the temporal amplitude variability trend of RWB and BWB sources we have used the 2-dimensional Kolmogorov–Smirnov test (KS-Test) where we found that the variability amplitude distribution of BWB and RWB sources are significantly different. n a comparative examination involving Broad Line Seyfert Type 1 (BLSy1) galaxies, a notably different scenario emerged, with approximately 39.5% adhering to the RWB trend and 60.5% following the BWB trend.
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