Re: Custom Tracking Rate woes

Ray Gralak

@Ray: I've read the help guide and the link, but I still don't understand what the "seconds" (numerator) refers to:
I assume you mean right ascension "seconds"? That's the distance in RA a star would travel in a sidereal second. A sidereal second is 1/(24*60*60) of a sidereal day, which is about 23 hours and 56 minutes.

You can see that if you enter a 1.000 in both RA and Dec that the RA and Dec coordinates update about 1 unit per second. This makes a Dec=1.000 about 1/15x of the RA=1.000 rate, as per the ASCOM specification.

One reason an application may not work is that the Dec direction is not defined in ASCOM, so what one mount manufacturer defines as a positive Dec move might be a negative Dec move for another manufacturer. Thus, an application may need to discover the Dec direction if not pre-configured with the correct Dec directions for a particular mount (btw, the Dec direction can change sign after a German equatorial mount pier flips).


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