The task noao.rvcorr can be used to compute values for heliocentric corrections by hand (rather than hidden inside another task).

The task noao.rv.rvcorr can be used to compute values for heliocentric corrections by hand (rather than hidden inside another task). Compute the various components of the heliocentric corrections, for the StarA spectra, and put them in a table. Then, plot the components of the correction as a function of Heliocentric Julian Date: vdiurnal , vlunar , and vannual . Also, plot the total correction vHelio . Calculate roughly how much difference you might expect between a barycentric correction (correction to the centre of mass of the solar system) and the heliocentric correction. How does this compare to the accuracy of IRAF"s heliocentric corrections? Would you need to do a full barycentric correction if you were doing a radial velocity search for extrasolar planets? Choose a high signal-to-noise spectrum of StarA as a template spectrum. Use noao.rv.fxcor to measure the radial velocities of all the StarA spectra relative to this template, but define the spectrum sample regions so th