Some Winter favourites

Seanie_Morris wrote:

Wow, John, nice work. Can't wait to see the final results, especially on the M42 Orion shot. Hurry up!

What do you mean by taking them "on a CGE without guiding"? Did you have motor function but no guidescope?

Seanie.

Thanks Seanie

I was not using an autoguider for thse shots (not using a guidescope). The CGE tracks pretty well as long as there is a decent polar alignment. A four star align followed by the internal polar alignment routine is all I did.

Thanks for that John.

I managed to get out in the cold last night and take some more shots. The fog rolled in before I could take some extra horsehead shots:(



Rosette nebula

17 x 5 minute subs. Megrez 72 Canon 450D (unmodded). Darks (6) and flats (10) taken. Fog rolled in at frame 18 !! No autoguiding used.

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Pleiades M45
I decided to reshoot this one using longer frames. This is a composite based on 9 x 5 minute subs with flats and darks taken using the same set up. I am using a Skywatcher field flattener which is non reducing (flattens only- does quite a good job for £60)

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This is all the processing I can do as I only have DSS and Gimp :whistle:

Hey John, I'm only waking from hibernation now, I would have posted earlier. Congrats on just getting out there to do these shots, it's exceptionally cold ! Fair play to you.

A four star align followed by the internal polar alignment routine is all I did

Could I ask how you do this (apart from the obvious:blush: ) I can get about 2 minutes unguided on my new CGE, the 4 star align would be easy alright, how do you do the 'internal polar alignment routine'? It's time for me now to do this as well, time to get the manual out once again, thanks,

Keith..

Hi Keith

To use the CGE polar alignment.
1) Set up the scope as close to north as you can visually. This is important as the CGE has a very limited range of adjustment in azimuth.
2) do a two star align with two extra calibarion stars (4 in total -well seperated east and west)
3) Go to the menu. Select utilities. Select polar align/ do polar align. The scope will slew to where it thinks polaris should be. Put the hand controller away so it cannot be used.
3) Loosen the azimuth knobs and the two hex screws on the altitude axis and using the hex key adjust the axis until polaris is centered in the field of view of say a medium power eyepiece.
4) When centered press enter on the hand controller. The mount is now polar aligned. Tighten all the knobs !!
5) Redo the 3 or 4 star align calibration and you should be ready to go.

John

This polar alignment method looks to me to be the iterative method - though it's not clear from your description that iteration is involved.

Also it would appear that syncing / aligning on only one star should be needed.

The following link goes into some detail on the method

www.covingtoninnovations.com/astro/iterating.pdf

The method is advocated by Craig Stark (author of PHD) and appears to be in widespread use.

I've been just doing Polaris hour angle method (and short exposures) to date and will be looking to try the iterative method.

Mark