A New Narrow - Line Seyfert 1 galaxy : RX J 1236 . 9 + 2656

We report identification of a narrow-line Seyfert 1 galaxy RX J1236.9+2656. X-ray emission from the NLS1 galaxy undergoes long-term variability with 0.1– 2.0 keV flux changing by a factor of ∼ 2 within ∼ 3 yr. The ROSAT PSPC spectrum of RX J1236.9+2656 is well represented by a power-law of ΓX = 3.7 +0.5 −0.3 absorbed by matter in our own Galaxy (NH = 1.33 × 10 20 cm). Intrinsic soft X-ray luminosity of the NLS1 galaxy is estimated to be ∼ 1.5 × 10 erg s in the energy band of 0.1− 2.0 keV. The optical spectrum of RX J1236.9+2656 is typical of NLS1 galaxies and shows narrow Balmer emission lines (1100 km s < FWHM < 1700 km s) of Hβ, Hα, and forbidden lines of [O III] and [N II]. Fe II multiplets, usually present in optical spectra of NLS1 galaxies, are also detected in RX J1236.9+2656.