Hi John, Just to be clear: - Epoch = the date used for the proper motion correction - Equinox = the date used for the precession correction - Nutation and aberration are corrected for apparent coordinates. - Refraction is always corrected for Alt/Az coordinates, but this as no meaning for equatorial coordinates.
The order of importance of the correction with a scale order is refraction 30', precession 10', nutation 10", proper motion 5" Sure there is exception, Polaris precession is much more important as is the proper motion of Barnard star. The setting is in Configuration/Chart,Coordinates/Type of coordinates. For the use during an observational session I recommend to keep the default "Apparent". The three other setting are mainly to allow coordinates comparison with atlas, catalogue or ephemeris data. Any setting you choose here the coordinates send to the telescope are mean J2000 RA,DEC, just the Epoch can make a difference if the object is a star. This mean Equinox=2000.0, no nutation correction, no refraction correction. It is the telescope driver or handpad responsibility to convert that to local apparent coordinates. Patrick
