M57 - Testing 1-2-3

At long last this is First Light with my Celestron EdgeHD 800 Schmidt-Cassegrain Telescope (SCT). I purchased this specifically for the many small galaxies of galaxy season. I missed that but fortunately there are a plethora of other small objects which I have avoided over the years. Although I have imaged M57 or The Ring Nebula before, I selected it again because it was bright and in an ideal location for me to do all of this testing. I am very happy with the final images especially given the limited exposure time. I was only using this object as a test and will try something that I have not done before if it ever clears up.

If you are interested in more detail, read in between the paragraphs, otherwise skip to the conclusions and image descriptions.

Data Collection
The first night out I successfully did the collimation, autofocus, and tried some imaging using NINA and APT to no satisfaction and plenty of frustration. The problem may be the computer or Microsoft - whatever the case I ditched it for the Asiair Pro. We have had a horrible stretch of weather here so testing has been exceedingly slow. The next time (a few days later) I had the Asiair Pro up and running. Everything worked - slewing, plate-solving, autofocus, autoguiding, meridian flip, and parking the scope. On the second night (7/5) I collected 60 x 90 second frames with no filter. Also on the second night I collected 19 x 180 second frames using the IDAS NBZ filter. In my haste I did not check the collimation beforehand and noticed it may not have been the best it could have been. The third night (7/11) I did collimate the scope and managed to collect 36 x 90 second frames making the total exposure 96 x 90 second or 2.4 hrs.

Brief Discussion
After reviewing the data from both nights, the collimation was not that far off so it was usable although I should check it every night. I replaced the collimation original screws with Bob’s Knobs which are much easier to adjust. The stars turned out much better than I anticipated they would. They were round (in the central region) and tighter than I thought they would be using an SCT with this focal length (I was expecting them to be more bloated). I recently discovered the color astro cameras do not come with built-in UV/IR filters which can add to star bloating which may have contributed to the large stars of my recent Iris Nebula image using the ASI294 and Canon Lens. I used the same setup on the Elephant Trunk Nebula only with the IDAS NBZ filter and no bloat. The stars on corners of the images are pointing towards the center, this is a classic indication that back focus needs more space. It is close so not too much space is needed.

There were problems with the support frames in particular with the flats. After many trial sets I was able to produce a usable set for the unfiltered data. I was never able to produce usable flats for the NBZ filter. I did order a light panel to aid in this effort. What a pleasure it was to use my old autoguider (6 yrs old) the Orion ST80. This is currently sold as part of the Awesome AutoGuider Package by Orion. I had forgotten how pleasant and easy it is to use a ‘real focuser’ rather than the helical focuser.

Lastly, the Field of View (FOV) for the Edge is much smaller even with the focal reducer than the AT115 which translates into more detail for smaller objects. One of my images shows the comparison between the two using the ASI294. Another way to look at it is the ASI294 uses 11.7 Mp to make an image, therefore, the image made with the Edge will be more detailed than the one made with a cropped AT115 image.

Conclusions
- Collimation adjust every imaging session 
- Backfocus is close as is, however, will adjust in an effort to improve
- Dark Frames look good and do their job
- Flats are going to need some work before I use them
- Orion ST80 with ASI120 mini Autoguider setup works well

Descriptions
Image 1: Cropped - unfiltered RGB + IDAS NBZ (partially)
- The NBZ data was not good enough to make a complete image but was able to use a portion of it to accentuate the Ha/OIII gas surrounding the main portion of M57

Image 2: Uncropped - unfiltered RGB + IDAS NBZ (partially)
- The NBZ data was not good enough to make a complete image but was able to use a portion of it to accentuate the Ha/OIII gas surrounding the main portion of M57

Image 3: Cropped - unfiltered RGB

Image 4: Uncropped - unfiltered RGB

Image 5: FOV comparison
- EdgeHD 8” with 0.7 FR and ASI294
- AT115 with 0.8 FR and ASI294

Image 6: Uncropped - unfiltered RGB
- After stacking and ABE

Image 7: with the Dust Bunny Nebula
- For submission to NASA?  I found a UFO pretending to be a dust bunny!

M57 - Ring Nebula

Dates: 7-5, 7-11
Camera: ZWO ASI294MC-Pro
Telescope: Celestron EdgeHD 800

Barlow: None
Focal Length: 2032mm (native)
F/10 (native)

Focal Reducer: Celestron .7 Reducer Lens 
Mount: Orion Atlas Pro
Filter Adaptor: ZWO Filter Drawer
Filter: IDAS NBZ (2-inch)
Focuser: ZWO EAF
Autoguiding: ASI120 Mini attached to an Orion ST80
Exposure: No Filter 96 x 90, NBZ 19 x 180
Gain: 120
Offset 0
Temp: 0 C
Processing: Asiair app, PixInsight, Photoshop, Gradient Exterminator, Topaz DeNoiseAI.

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