Calling all PHD users (improving guiding times)

[Robfal]

Advice needed on how to extend guide times. I currently use a QHY5 camera with PHD and EQDir connected to a EQ6 Pro. I can consistently guide for 300sec subs however above about 420sec I get elongation of the stars. What might I try to extend the sub time?

Options I'm currently considering are

1)poor polar alignment (I have to set up each time)

2) extending guide pulse times (Currently at 1 sec). This gives me a good star image to guide on. However I did think about putting a delay in (up to 4 sec)

Any suggestions on what I might try would be gratefully accepted

Rob

[SteveL]

Polar Align is by far the number #1 thing to work on for longer subs. Everything else is secondary.

Ignore the guiding interval, it wont have any affect. Longer delays will give you a better star SNR to guide on, but also longer for the mount to stray from where its suppsoed to be. Also, shorter guiding intervals give you a worse SNR and you can also end up chasing the seeing, rather than any real movement in the mount itself.

If you are seeing elongated stars at 420 seconds but not at 300 seconds, guiding is doing the same job the whole time. Its not like PHD suddenly turns evil at 301 seconds Work on Polar Alignment, there are several free tools out there to help (PolarFinder for a quick cheat, PoleAlignMax for accuracy but requires Maxim), and some fairly cheap options too (WCS is a good one to look for).

[blinky]

Got to agree with Stevel I would get hold of WCS and get your alignment as good as you can. I have an HEQ5 and EQMod and have had no trailing over a 10min sub.

[Ant]

Polar aligning is the key (as Steve Said).

I used WCS - fantastic bit of software... I aligned roughly using the polar scope. Then two minor tweeks to the Alt / Az on the mount (told what to do by WCS).

It took about 12 minutes (5 minutes analysis time and a minute adjustment for each axis).

I managed to get 10 minute subs with perfectly round stars - But when I stacked the images there was hardly any movement in 3hrs of guiding.

HTH

Ant

[Wobbly Bob]

What is WCS, tried googling and ended up with troublesome kids :scratch:

[SteveL]

http://wcs.ruthner.at/index-en.php

[Robfal]

I'm trying to use Polealignmax but it crashes on launching, any suggestions?

I have a QHY5, has anyone had success with WCS with this cam

Rob

[glennbech]

I don't know what U guys think but I have used PHD with guiding intervals max out to 10 seconds from time to time. I do this because I don't have guide rings at the moment and sometimes need to find "something" to guide on that I cannot see in my finder.

My polar alignment is okay, and I can do maybe 120 second unguided shots with no trailing. I'm thinking that the mount would not stray too far away, and that only minor corrections would occur in the 10 second intervals.

[Reggie]

best thing to do is turn the guiding off and look at the logs for phd (something I plan to do next time I can see stars) then you can see how much drift you actually get, whether its PEC or w/e. I plan to use another program for this, Metaguide, it has just had an update, to allow use of ascom drivers, I'm going to investigate these issues further, although I expect my mount to have plenty of PEC and drift as my homemade wedge doesn't have a decent enough RA adjuster. IMHO at least for testing optics, collimation and data logging metaguide seems the better equipped program. Haven't tried it for guiding yet.....