Minimum imaging angle

[Imme (Jon)]

I'm setting up a pair in my observatory and was wondering what the general consensus is on minimum imaging angle as this will dictate how high my pier needs to be.

So how low on the horizon is too low to image?

[billdan (Bill)]

I find that 35° Elevation is about as low as I can go, any lower and the sub exposures are worthless and just get thrown out.

[Imme (Jon)]

Cheers bill, thanks for the advice

[glend (Glen)]

I never image below 40 degrees, but my observatory pier and walls allow going down to 30 degrees visually. Remember your south end needs to be low enough so you can polar align.

[Imme (Jon)]

That may be an issue Glenn....my ob is built, 9mx6mx4m high shed with top 1.5m of roof that rolls off......and it rolls to the south!!!
Should be ok though. Once alignment is done scope will stay in place and tracking/multiple star aligns will handle the rest.....I hope!

[luka]

spam reported

[billdan (Bill)]

Yuch Spam

I always polar align at DEC 0 at the meridian with the PHD2 drift align utility for azimuth, and a low star in the west to set the elevation. So you don't need a view of the south pole, in my case I have a big gum tree blocking the south pole.

[Imme (Jon)]

Just measured up and 35' shouldn't be an issue with the material I have to work with.

Thanks guys

[jenchris (Jennifer)]

Aligning with a pier is really not an issue.
The need to align is only there when the gear is removed then reinstalled.
In my case that's about twice a year.
Once done all I do is turn stuff on and start imaging.
Mark the pier when you get it spot on amd you can virually forget it.

[Imme (Jon)]

My thought exactly Jennifer.....not too stressed on aligning at all.

Once it's done, it's done.

[The_bluester (Paul)]

I plan to eventually build an ROR obs and was aiming to try for views down to the decent visual limit.

It would take a little longer but finessing the PA by drift alignment should not be a problem there or if the pole is not visible. It just means ensuring that the azimuth adjustment is done first so that you can do the alt on a star a bit further off the horizon knowing that the alt is right otherwise you would chase your tail. Try to do the alt with a star at 45 degrees up without having gotten the az right and you are trying to adjust for what is actually a result of both alt and az errors.

Once it is done it should only need checking now and again or if the mount is removed.