Hi Robert,

I've heard from one gent with 8192 count/revolution encoders and a
Dob mount who, after a bit of playing with MEC, got pointing
accuracy of a few arcminutes. I dunno how well that represents
"general" accuracy, but I'd expect it to be about right. He _did_
have to acquire a couple of dozen stars, as I recall.

I suffer from a lack of data, because not many people have
actually used MEC. Give it a shot, and you'll see why: it's
ugly to use. Something I will be remedying...

As Jeff Medkeff mentioned, use of GSC-ACT doesn't help here.
The only improvement you get with GSC-ACT is that the positions
are adjusted slightly, to remove systematic errors. For details:

http://www.projectpluto.com/gsc_act.htm

No stars were added or removed, and no magnitudes were
adjusted. (I started a project to recalibrate the magnitudes, but
didn't have a great deal of success.)

"... I really don't want to haul USNO A2 outside." In theory, one
way around that would be to filter out the fainter A2 stars, and store
a subset of A2 on your hard drive. I did some of the math for this,
long ago, computing how many bytes would be needed to get to
a certain magnitude:

http://www.projectpluto.com/a2.htm#filtered

However, I don't have software to perform the necessary step of
creating a "filtered" A2.

A correction to my previous post: I suggested that Alan Cahill
(and anyone else so inclined) could copy RealSky, in part or
in whole, to a subdirectory on a hard drive, but would then need
to use the SUBST command or equivalent to make that subdirectory
"look" like a drive. I was wrong. All you need do is to edit the
file ENVIRON.DAT, in the Guide directory on the hard drive,
and look for a line resembling this one:

DSS_DIR=d:\

Change it to point to the directory on the hard drive where RealSky
(or DSS) data is installed, so it looks something like this:

DSS_DIR=c:\realsky\

No playing around with drive letters via SUBST is then required.

-- Bill