Method for retrieval of atmospheric water vapor using OH airglow for correction of astronomical observations

Abstract

Context. Water vapor in the atmosphere undergoes quick spatial and temporal variations. This has a serious impact on ground-based astronomical observations from the visible band to the infrared band resulting from water vapor attenuation and emission. Aims. We seek to show how the sky spectrum of an astronomical observation can be used to determine the amount of precipitable water vapor (PWV) along the line of sight toward the science target. Methods. In this work, we discuss a method to retrieve the PWV from the OH(8-3) band airglow spectrum. We analyzed the influences of the pressure and temperature of the atmosphere and the different water vapor vertical distributions on the PWV retrieval method in detail. Meanwhile, the accuracy of the method was analyzed via Monte Carlo simulations. To further verify the method of PWV retrieval, we carried out cross comparisons between the PWV retrieved from OH airglow and PWV from the standard star spectra of UVES using equivalent widths of telluric absorption lines observed from 2000 to 2016 at Cerro Paranal in Chile. Results. The Monte Carlo tests and the comparison between the two different methods prove the availability the PWV retrieval method from OH airglow. These results show that using OH airglow spectra in astronomical observations, PWVs along the same line of sight as the astronomical observations can be retrieved in real time. Conclusions. We provide a quick and economical method for retrieving the water vapor along the same line of sight of astronomical observation in the real time. This is especially helpful to correcting the effect of water vapor on astronomical observations.