Expected tracking with different alignment levels

Using SharpCap's Polar Alignment feature
Post Reply
DanInVa
Posts: 8
Joined: Wed Oct 25, 2017 8:48 pm

Expected tracking with different alignment levels

#1

Post by DanInVa »

I'm using phd for guiding. What should I expect from fair to good to excellent polar alignment? When I get on excellent, as soon as I tighten the mount down it goes from excellent to good. Is this ok for guiding or should I always work for excellent?
iOptron CEM25P mount
Orion 8" F/3.9 Astrograph
Zubenelgenubi
Posts: 18
Joined: Thu May 24, 2018 5:26 pm
Location: Texas USA

Re: Expected tracking with different alignment levels

#2

Post by Zubenelgenubi »

Up to about a week ago I used a iOptron phone app and polar telescope to align my CGEM for imaging. I could reliably get 3-4 arc minute alignment accuracy starting about one half hour after sunset. I recently started using the PA feature in SharpCap Pro to achieve alignment accuracies of 20-25 arc seconds! The only downside is that I need to wait until about an hour after sunset to get a high enough star count in my guide scope using a LodeStar camera.

I am seeing that the improvement in PA does not necessarily translate in significantly better PHD2 tracking in terms of rms tracking error. The better PA results in fewer guidance updates but it appears that that seeing conditions dominate the tracking errors.

BTW I am very impressed with the SharpCap PA and will continue to use it for my alignment.
User avatar
admin
Site Admin
Posts: 13173
Joined: Sat Feb 11, 2017 3:52 pm
Location: Vale of the White Horse, UK
Contact:

Re: Expected tracking with different alignment levels

#3

Post by admin »

Hi,

glad you are enjoying the polar alignment feature. Do remember to set your lat/long in the settings and enable the refraction correction feature which will improve alignment further. You could also try using the digital gain control for your Lodestar camera to see if that helps pull out enough stars during the earlier part of twilight.

cheers,

Robin
Pogo
Posts: 4
Joined: Sun Aug 19, 2018 8:13 pm

Re: Expected tracking with different alignment levels

#4

Post by Pogo »

I plan on using the Lodestar as well for my polaralignment routine, but noticed that the Lodestar has non-square pixels. Will that affect the result? Obviously you did get it to work.
Post Reply