Polar Aligning and Imaging Misery

[gfletcher]

Hi Guys

I need help!

I have a C8N newt on a motorised CG5 mount.

Polar Aligning:

1) I use the software "Polarfinder" to find the position of polaris at the time of polar aligning and religiously try to position the pole star on the circle of the polarscope in what i think is the correct position.

I assume the view shown on the software at the specific time of polar aligning means i just have to turn the RA axis so as the cross lines in the middle of the circle are truly vertical and horizontal as i look through the polarscope and align polaris in the position shown on the software by means of adjusting the altitude and azimuth on the mount ?

2) The view from the software shows 2 circles (an outer and an inner), do i assume that the position of polaris (as shown on the inner circle)is effectively the circle i see throgh the polarscopeor is the outer circle on the software the same as the circle seen through my polarscope ?

3) I assume by using this method,i dont have to bother with calibrating the position of the small polaris circle,i.e by using the date circle,time circle and time meridian indicator as mentioned on the polarscope instructions.

Am i right in thinking this ?

4) Using the method i describe above, when imaging, if i try to image at anything over about 30 seconds (sometimes less), i get star trailing !!

I am obviously doing something wrong or have assumed something i should not have.

Please can someone offer some advice as it is very frustrating.

thanks Guys

Graham

[Astro_Baby]

Two things spring to mind if your having problems.

1/ Is the polarscope aligned to the mount. ie does it track reliably with the RA axis. I dont know the CG5 mount but I gather the polarscope is held in with some adjusters that 'target' it - these are like the adjusters on a finderscope.

2/ Polarfinder gives you a view of what you;d see through ( I think ) a Sphinx reticule. No idea what the CG5s polarscope reticule looks like but in any event polarfinder has a Polaris Track circle - the circle around which Polaris will 'orbit' the NCP.

You can just look at Polarfinder and set your mount ( using the RA axis ) to mimic the view in Polarfinder and then align the mount onto Polaris but at anything other than a transit point ( ie when Polaris is either at the top or the bottom ) then I suspect its going to be a bit hit and miss.

Setting the time/date indexes on the scope isnst that hard once you have cracked it I found. I have no idea how helpful my HEQ5 guide would be to you. The principles are the same for any mount with a polarscope. It may give you a comparitive view of stuff if nothing else.

The guide is at http://www.adur-astronomical.com/HEQ5/HEQ5-1.htm

[Aza]

Graham

I use PolarFinder and basically rotate my RA axis until the outer circle matches the position shown in the software.

Then using the mount mechanics position Polaris into this circle.

However this is still fairly inaccurate when going for imaging. So I then use the Iterative Polar Alignment method to make it even more accurate. It sounds complicated at first, but is actually pretty simple:

http://www.cloudnet.com/~dsastro/PolarAlignIT/PolarIterative.htm

Good luck!