The atmospheric water vapor retrieved by OH(8-3) band airglow from astronomical observations

Abstract

<p>Water vapor in the atmosphere is an important trace gas, and seriously affects the ground-based astronomical observations due to water vapor attenuation and emission. It is significant to correct the effects of water vapor along the line-of-sight of astronomical target in real time. Here, we discuss a method to retrieve the precipitable water vapor (PWV) from the OH(8-3) band airglow spectrum. The pressure, temperature and water vapor profiles determine the effective absorption cross-section in PWV retrieval, so a simple and effective method of the effective absorption cross-sections using profiles from a standard atmosphere model is discussed. The Monte Carlo simulations are used to estimate the PWV retrieval. Besides, the PWV is calculated using the sky nightglows from UVES and is compared to that from the standard star spectra of UVES observed from 2000 to 2016. The results indicate that The PWV derived from OH(8-3) spectra is in good agreement with that retrieved from UVES standard star equivalent width and the averaged difference between the two is 0.66 mm. The regression result indicates that the slope α=1.06 +/-0.03 and the correlation coefficient is r=0.87. Because the sky emission spectra and the astronomical target are observed at the same time and along the same line-of-sight, the method of PWV retrieved by OH(8-3) band spectra provides a quick and economical means of correcting the effects if water vapor on ground-based astronomical observations locally, in real-time, and along the line-of-sight of astronomical observations.</p>