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Paper: High precision Doppler measurements via echelle spectroscopy
Volume: 8, CCDs in Astronomy
Page: 335
Authors: Brown, Timothy M.
Abstract: With modern echelle spectrographs and CCD detectors, photon noise permits one to measure the radial velocity of bright stars with precision as good as 1 m/s in 60 s of observing time. In order to achieve this precision in practice, measures must be taken to control several sources of instrumental noise. Two distinct methods have evolved to do this: (1) use of a molecular absorption cell to impress lines of constant wavelength on the incoming starlight, or (2) use of a fiber-optic feed for the starlight, in conjunction with a second fiber carrying light from a stable wavelength source. At the current state of development, the first method yields better long-term stability (useful, e.g., for planetary detection), while the second method provides better S/N per unit time in circumstances where low-frequency stability is not required (such as observation of stellar oscillations). For both methods, details of instrument setup, data acquisition, and data analysis are important for getting the best results.
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