Power Spectrum Analysis of Time Series in Positions and Intensities of Solar EUV Lines Observed with 0S0-8

Extract

Several hundred hours of observing time with the University of Colorado spectrometer on 0S0-8 was devoted to rapidly repeated scans of one or two spectral lines while the instrument was pointed at a fixed location on the solar disk. These repeated line scans provide time series of line profiles at a given location on the sun from which we extract information on the line intensity, central wavelength and width. The data reported here are for the λ1816.93 and λ1817.45 lines of SiII. These lines are members of the same multiplet and have a gf ratio of 10:1. The lines were scanned with a slit or 1 x 20 arc second size projected on the sun. About half of the experiments were conducted by scanning only the 1816.93 line with a repeat time of about 15 seconds and about half included alternate scans of line λ1816.93 then λ1817.45 with a repeat time for each line of about 28 seconds.