Spectral observations of the California nebula (NGC1499, Sh2-220) and determination of its some physical parameters

In this thesis study, Hα (6563Å) emission line spectra selected from thirty-six regions of the California Nebula (NGC1499, Sh2-220 LBN756; α=04sa03dk18.0s, δ= +36˚25'18.0"; J2000) located in the constellation Perseus have been investigated using DEFPOS spectrometer with a 4 arcmin circular field of view over a 200 km/s (4.4Å) spectral window at the coude exit of the 150 cm RTT150 telescope at TUBITAK National Observatory (TUG, Antalya, Turkey). The California nebula with a very large emission nebula (145'×40') is a nearby HII region called as Sh2-220 in Sharpless Cataloque. In observations on November 1-3, 2017 were carried out with different exposure times ranging from 600 to 2400 seconds to obtain enouhg signal form the source. These spectra provide detail information about the intensities line widths, and radial velocitiesof the ionized hydrogen gas in the California Nebula. The line width, the radial velocity and the intensitiy values obtained from thirty-six Hα emission line spectra were found varying from 31.05 km/s to 40.26 km/s (mean 35.10 km/s), and from −13.83 km/s to -8.84 km/s (mean -10.77 km/s), and from 235.17 R to 825.967 R (mean 462.03 R), respectively. The mean emission measures (EM) were also calculated using the IHαvalues and were found ranging from 529.057 cm−6pc to 1858.133 cm−6pc (mean 1039.41 cm−6pc). The mean LSR velocities and line widths of the NGC1499 nebula were compared with some previous works from literature. The intensity data been also compared with the data obtained from VTSS and SkyView maps using APER and SKY codes. We found that our results were approximately the similar variation with VTSS (mean 430.91 R) and SkyView (mean 530.53 R) maps. We believe that these new results may have significant contribution to the literature. In future, we will continue to measure the other coordinates of the NGC1499 nebula.