[net.astro.expert] Question: Errors in R.A. and Dec.

tdxsys@dartvax.UUCP (TDX sys Mark Mullen) (07/14/84)

        To what degree of accuracy can astronomical observatories measure
the RA and DEC of celestial objects?
        Errors in measurement dure to rotation amay account for ten seconds
of arc.
        Neglecting,perhaps, transits used by U.S. Naval observatories, can
observatory telescopes measure true RA and DEC to, say, one second ofr arc
with just one sighting?