Читать книгу The Doppler Method for the Detection of Exoplanets - Professor Artie Hatzes - Страница 41

The fundamental characteristics of a spectrograph that can influence the RV precision are

 the wavelength coverage,

 the resolving power of your spectrograph, and

 the S/N of your data.

An increased wavelength coverage usually results in more spectral lines to measure your Doppler shift. All other factors constant (i.e., the properties of the star), the spectral resolution determines the recorded width of your spectral line and how easy it is to measure its centroid. The S/N naturally depends on the brightness of the star, the exposure time, and the observing conditions. If all these factors are equal, then the S/N also depends on the efficiency of the spectrograph. We therefore include it among the instrumental characteristics.