To provide a familiar interface, and since the functions are so similar, the task rvidlines works much like identify. A dispersion calibrated spectrum is read and the user marks lines and provides the rest or reference wavelength. One enhancement over identify is that the line centering algorithm includes Gaussian fitting and deblending in addition to the standard centering algorithm. With one or more lines a radial velocity is computed, and both rest and observed wavelength scales are shown. Line identifications can come from a coordinate list. The list is in rest wavelength so if there is a significant velocity shift one can mark one line to get a first estimate of the velocity, and then the rest of the lines in the coordinate list can be automatically found. When there are multiple lines the measurement produces a mean velocity and error estimate based on the scatter of the individual lines.
The state of the identifications can be saved in a database file and a log of the identified lines and measured velocities (including heliocentric corrections) and errors will be written.
The rvreidlines task is, naturally, modeled after reidentify. It takes the lines identified first with rvidlines and automatically finds, recenters, and recomputes velocities for other spectra. This is useful when there are many observations of the same object or objects of similar velocity and spectral features.
Frank Valdes
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