Generalized function to load one or more orbit files.
obs_name (str) – Observatory name. (Fermi, NICER, RXTE, and NuSTAR are valid.)
orb_filename (str) – An FT2-like file tabulating orbit position. If the first character is @, interpreted as a metafile listing multiple orbit files.
orb_table – A table containing entries MJD_TT, X, Y, Z, Vx, Vy, Vz
astropy.table.Table