polar align with wedge

[ryanpaul]

hi all, i have a celestron nexstar 8se, and celestron wedge, i have had my scope for a few months now and am about to start entering the world of astrophotography. have spent the day reading all the info i can on polar alignment with the wedge i have a few questions.

my main on is, i mainly use my scope in my back garden, which faces south, and cannot see Polaris, how can i therefore polar align the scope?-

secondly, once i have actually managed to align, do i need to do this every time i use it, even if i put it back in the same spot?

thanks in advance all

Paul

[blinky]

I have an EQ mount but the principles as the same. If you cannot see Polaris I suggest you get hold of WCS, in fast even if you could see Polaris get WCS! Makes polar aligning easy!

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

You point it at a sat and it tells you the drift and how to adjust the mount to correct it.

If you are going to do long exposure astrophotography the you will really need to do a drift alignment each time for the best accuracy.

[ryanpaul]

thanks mate, just tried it, but does not seem to work with my windows vista- typical!

thanks anyway

[Ajohn]

I've outlined one way of doing it with any star in another thread asking about polar alignment. In your case after trying it you might decide you could do with an eyepiece with cross hairs. Also make sure the mount is level and set the lat as close as you can. It's a case of learning what the star drift seen through the eyepiece means in terms of the mounts alt az adjustments. It doesn't take long to learn and they drift really quickly in a high powered eyepiece.

Goto can also be used. With Vixen you set up as best as you can using a compass offsetting for true north and a spirit level to level the mount. Do the 1st alignment as normal but the 2nd one with the alt az adjustments. Vixen allows any currently viewed object to be used for alignment at any time but it seems to me if the goto is switched off and the process repeated the mount must be perfectly aligned eventually. Some goto's will use some alt az drive even when the mount is in aligned equatorial mode. That's why I suggest turning the thing off. That way when the 2nd alignment is spot on the mount must be spot on too. Haven't tried it yet but I'm sure it will work. Nice thing about it is that with Vixen at least it's possible to align on any 2 suitable stars.

It didn't occur to me until I read a slight variation in the Vixen hand book but that method may leave some alt az drive in.

John