In ground-based astronomical spectroscopic observations, there are many telluric absorption lines that are laid on the spectra of celestial objects. To study the physical properties of the celestial objects with these contaminated spectra, the telluric lines should be removed. A conventional method for removing the telluric lines is using the standard stellar spectrum as telluric line. In this paper, we introduce a technique to calculate synthetic telluric spectra and use them to remove telluric lines from a spectrum of a celestial object. We used Line-by-Line Radiative Transfer Model (LBLRTM) for calculating a synthetic spectrum and selected Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) model as atmospheric model. We apply our method to some spectra obtained by Bohyunsan Observatory Echelle Spectrograph (BOES) to show that the telluric lines are well removed from the observed spectra by our model within an accuracy of 2% which is close to the 1-sigma rms of the original spectra.

태양 복사의 지구 대기 산란광을 근 적외선 영역에서 분광 관측하여 H2O와 O2 흡수선을 측정하고 이것으로 태양 복사량에 따른 두 기체의 등가폭 변화를 계산하였다. O2는 태양 복사량이 증가할수록 등가폭이 줄어들고 복사량이 감소할수록 커지는 경향을 보였고, H2O는 그 반대의 경향을 보였다. 특히 두 기체가 만드는 흡수선 등가폭의 합은 하루 중에 대체로 일정한 경향을 보였다. 본 연구에서는 이것이 태양광에 의한 광해리와 재결합이 O2와 H2O에 있어서 상호 보완적으로 일어나기 때문으로 추측한다.

We present a method to improve the RV (radial velocity) measurements accuracy by using telluric lines. Telluric lines are used to estimate the wavelength scale drift over the detector of the spectrograph. In the case of BOES, the Echelle spectrograph at BOAO (Bohyunsan Optical Astronomical Observatory), the wavelength scale drift can be several hundreds m/s over 24 hours. Due to the wavelength scale drift, the RV measurements accuracy of BOES is limited to several hundreds m/s. By estimating the wavelength scale drift by telluric lines, we can remove its effect to improve the RV measurements accuracy to about 40 m/s.