[gary]

Originally Posted by rider

The accuracy of the Argo is only comparable (at best) with the synscan unless you use the advanced pointing software - this is pretty useless on a portable mount, because you spend half your night training the mount. Its easier and quicker to just recalibrate it for the part of the sky you are looking at with a one star alignment.

Hi Rider,

Thanks for the post.

You may not be using the pointing analysis system as is intended.
Specifically there is no need to spend that amount of time to re-synchronize
the pointing model. The following tip might be helpful.

What we recommend is a two-stage process.

On one night, say on some unfavorable observing night like on Full Moon,
we recommend you perform a long sampling run where you sample star
positions across the whole sky and fit a model. Any terms in the model
that are significant and whose nature is such that they are likely to be
persistent from session to session you should make the selection to
save into the non-volatile memory. Persistent terms are terms such as
non-perpendicularity between RA and Dec (NP), any flexure terms (TF & DAF)
and any eccentric bearing error terms (DCEC, DCES, HCEC, HCES).

Now - and this is the really neat part - on a subsequent night's observing you
simply need to re-synchronize the model by sampling four or five stars.
You would then fit the two non-persistent Index Error terms (ID & IH) and the
polar misalignment terms (MA & ME) and possibly the collimation in
hour angle term (CH), which comes about if there is any non-perpendicularity
between the declination and optical axis. This later short sampling run
should take you less than five minutes to perform but the beautiful part is that
your pointing performance will return to the same levels as it did as on the
night when you performed the long sampling run.

Whenever I use an equatorial mount, I use this same approach myself at the
beginning of the night as it is just getting dark and I wholeheartedly recommend it.

(also, be aware of the significant extra drag the argo senders place on the motors)

Sorry, but that is not correct. The encoders produce negligible and insignificant
drag to the motors and gear train. The encoder shafts can be rotated with the
fingers and have as much torque as a volume control on a car radio. Compare
that to the huge moment of inertia of the OTA and the counterweight which the
motors and gear train are also driving and you can appreciate that the encoders
provide a minuscule loading. For example, If one were to measure the current
draw of the motors with and without the encoders in place, which is one way to
measure the loading, rest assured the difference would be incredibly tiny.

Thanks again for the post and I hope the tip on using TPAS is helpful
as well as the clarification on the tiny moment that the encoders present to
the motors.

Best Regards

Gary Kopff
Wildcard Innovations Pty Ltd