High resolution spectroscopic measurements and modeling of the O2 (1,0) atmospheric system band

The rotational absorption lines from the P branch of the molecular oxygen atmospheric system (1,0) band (687 nm - 697 nm) have been used for the effective temperature evaluation. Ground based spectroscopic observations have been performed during June/July 2006 at the solar telescope of Belgrade Astronomical Observatory. A spectral resolution of about 105 has been achieved. The linear dispersion is 20.8 mm/nm at λ≈690 nm. 20 observational sets were performed consisting of the CCD spectrograms centered at the wavelengths of the chosen 13 line doublets with rotational quantum numbers from 1 to 25. The signal to noise ratio has been estimated about 400. A synthetic spectrum of the (1,0) band has been created based on line-by-line calculations. The theoretical and measured line profiles and their equivalent widths have been compared. A good agreement has been obtained in all cases taking into account the presence of water vapour lines. The dependence of the equivalent widths on the rotational quantum number has been worked out assuming strong absorption. It allows the evaluation of the effective atmosphere temperature. The possible contaminations in some cases are discussed. The theoretical estimates and the measurement results have been examined.