At 08:52 AM 2/28/2007, Bryan Henry wrote:

I do visual work and find a pointing model to be very useful for
improving accuracy with a less than perfectly aligned AP900. It has
nothing to do with bragging rights and everything to do with locating
an object at the edge of detection. I understand the mount is
mechanically capable of incredible pointing accuracy when the RA axis
is nearly perfectly polar aligned and the telescope OTA is
orthogonal. But when you have 2 hours and must set up from scratch
there is not much time for achieving this alignment perfection. In
this case having a model to continually improve accuracy while you
observe makes sense.

Bryan: I certainly wasn't trying to belittle anyone's effort to improve their pointing.
I have an older AP800 mount but usually use my Paramount ME when I go portable
(although it is usually in my observatory) ... I use TPoint to polar align and THEN I do
a small pointing model later (I also have TheSKY PE with TPoint).

It had been my experience though that the polar alignment scope got me pretty close for visual
observing so that pointing was not too bad. But, it of course depends on the FL of the OTA and
whether you are sure of what you saw - i.e. if you are trying to see things at the limits of detection,
I understand one feels more honest if they were more sure that the object WAS actual in a place
to be seen, rather than using averted imagination. I usually don't try to find real faint things visually
with the 7" f/7, but maybe the time has come to push the envelope a bit!

I use the PDA version of The Sky with TPoint and it improves the
pointing enough to ensure the object is very near the center of the
field with a casual setup of my AP900. Having this capability in the
hand control would be more useful because there is one less device
and fewer things to go wrong. TPoint also provides the ability to
tweak various model parameters for even greater accuracy but I just
use the default parameters and find it works fine. Hopefully the AP
implementation will make it simple and easy to use.

Well, Rolando et al have been pretty innovative in the past, so nothing would surprise me. Since you
have TPoint, you'd have the best of both worlds.

Enjoy,
Dave