Dear Reader,

With the Galaxy season fast approaching I decided to switch to my Celestron C6 SCT in order to zoom in on those small and intriguing targets.

I had one new addition to my system - an off-axis guider from Celestron. The last off-axis guider that I tried on this scope was from ZWO but did not have any luck with it and managed to return it to the store - at least that was something nice I performed the acquaintance and installation of the Celestron guider during the day. What I can say is that the Celestron Off-axis guider is really well assembled and of excellent quality. The included adapters and extenders in the box are the best bundle that I have seen up to now and are worth it. In my opinion it is the perfect accessory for every SCT.

After assembly I tested the system by pointing it at the summit of the nearby Vitosha mountain. I faced several hindrances which I had to overcome:
- I could not reach focus with the guiding cam when the main cam was focused.
- I solved the above by adding some spacers to the main cam. The Celestron off-axis guider has several T2 extenders included in the box so this is very nice in my opinion.
- Then I found out that not the whole field of view of the guiding cam was illuminated.
- I solved this issue by inserting the prism of the guider as farther in as possible.

Ok, after the above intervention the system looked good to go. The next thing that I did was to put the scope on the mount and balance it. This wasn't an easy task as well. Having the guider, two cameras and lots of cables on the back made the scope back heavy. I solved this by using an ADM rail counterweight - an excellent accessory as well

The next thing was the field test under the stars. A nice surprise turned out the fact that the camera was focused out of the box and the guiding cam was in focus as well. By using the off-axis guider I acquired the following new knowledge for me:
- by switching to off-axis one should change the settings of PHD2 and increase the focal length of the guiding scope as this is now the main scope (doh...);
- guiding should not be active during a refocusing routine as the guiding star may be lost and guiding may fail;
- if some clouds roll in then guiding is immediately lost and the guiding and imaging sequences becomes hard to automatically recover;

However once all of the above is sorted out:
- guiding through an off-axis guider is rock solid.
- there is no drifting of the scope at all. The only change in the frame comes from dithering.
- i can use 10 minute frames - no problem and no matter where the scope is pointing to. Pointing it near the zenith - no problem. Stars are round.
- median of the eccentricity of the stars from my session was estimated at 0.42... Haven't seen such result up to now.

Another thing to mention is that I used the 0.63 focal reducer in order to make my life a bit easier with finding a guide star and increasing the speed of the scope.

After all of this preparation I pointed the scope to NGC 2841 - the Tiger's eye galaxy. I am happy with the result and even managed to capture lots of small PGC galaxies in the background. My image has also lots of comets and even two diamond rings. The normal SCT rules As the field is not flat at the edges I guided on a melon shaped star - screen is attached.

I hope that in the future I will be able to make even clearer photos of such distant objects with a bigger SCT or clearer atmosphere.

CS,
Ivan