Cocoon and the Crescent
After fighting with my Celestron CGEM DX for years, I finally bit the bullet and ordered myself the new ZWO AM5N harmonic equatorial mount. I decided to go with ZWO because I already have a few of their cameras and was recently graciously gifted an ASIAIR from a club member. So September 3, 2024, was the first light with both the mount and the AIR. I only ever connected the AIR to my phone/iPad but never used it. Also, I was really interested in the new mounts because of the light weight compared to carrying capacity. I found myself not bothering to shoot many nights with my current rig because I did not want to carry out 150 pounds of equipment just to be cursing my mount for two hours.
The ZWO AM5N mount came with the factory periodic test graph. It showed +6 and -6 arc seconds which seems incredibly good compared to some other YouTube reviews. The limits on the new mount are supposed to be a maximum of 10.
Last night I went with my Meade ACF 8″ F10. It would have probably been a better idea to start testing with a much less demanding scope, but this SCT has been more or less useless with my old setup. It was a scope that came off of a single arm mount with no mounting holes for any guide scopes. Previously I had to Frankenstein my own plates out to make a dual saddle for a small refractor for autoguiding. When I got my ASI 2600mc duo camera (guiding chip on top of the imaging sensor), I figured that would solve this issue. Unfortunately, the ASCOM would not play all that nicely with my CGEM DX. I have only been using my 8″ SCT at the AAA park meetups using 15-second exposures/high-gain live stacking. That worked well enough for the public but not for any serious imaging.
Tom’s rig on his backyard deck. Credit: Tom Cuccia
The testing started off on my backyard deck in Old Bridge, NJ. It is a new deck with composite flooring so I would never dream of sticking my old heavy mount on there, where it would dig holes into the boards. I thought it would be a nice place to shoot from since I can just move it in and out of the house super quick.
Unfortunately, I only have a ridiculously small opening in the trees to get to the north celestial pole (NCP, or Polaris). It started well enough to plate solve but as I was getting closer, I was in the trees. I had no idea how to polar align with the ASIAIR and this mount without NCP and that’s something I need to research. Since this new mount is so light I just unplugged all the wires and lifted the whole setup down into the yard. Easy peasy. I found a nice spot with a clearer view of the NCP and took just a few minutes to get aligned.
Tom’s rig, with trees in the background. Credit: Tom Cuccia
From here it was more of a lesson in using the ASIAIR than the mount. Just pressing buttons, hopping around from DSO to DSO, plate-solving, all that good stuff I haven’t been privy to. The mount worked amazingly well, so quick and quiet. I ended the night with a 10 x 5 min run of C19, the Cocoon Nebula with my Askar Color Magic Ha+O3 narrowband filter. Now that’s a really tall order for autoguiding: a 2,000mm scope at F10 off-axis through narrowband. The mount performed exceptionally well. Most of the time I was getting a total RMS error of 0.33″ using 3 seconds for guiding.
I would have loved to spend hours on this object but needed to call it a night. I have lots more testing to come such as the polar alignment without NCP, meridian flips, and such, but I couldn’t be happier.
I next brought out the rig on Sept 5. The night started out well enough. For convenience, I really wanted to shoot from my deck. Unfortunately, there is only 1 spot in my yard with a clear view of the NCP and it’s not where I want it. So, the normal Polar Alignment function would have to be changed. In the ASIAIR there is an All-Sky Polar Alignment function that can be enabled letting you use an alternative method. Using the All-Sky Polar alignment feature in ASIAIR, I started out with the bright star Altair. Being quite a bit off, I physically moved the mount to get the star inside my Telrad finder. Since the rig is much lighter with the AM5N mount, moving everything is much easier.
After a quick plate solving, the mount then maneuvered itself to another area of the sky, perhaps 60 degrees away. It plate solved and once again moved to another area of the sky for a final plate solve. This all happened with no interference or input from me. After it finished its business, it told me I was 30 arc minutes off in altitude, and 1 degree off in azimuth, not too bad of a starting point. A few minutes of fiddling with the alt/az knobs and I was shooting. This process was a whole lot less painful and tedious than with my old mount. My only issue is that there did not seem to be any manual override in case I needed it to look elsewhere. As you can see from my setup images,
I’m surrounded by quite a few trees. On the mount’s final stop for alignment, it was probably a handful of degrees away from the tree line. If that failed, the whole process would have failed, and I would have had to try starting elsewhere.
The Crescent Nebula (NGC 6888) in Cygnus. Integration: 39 x 300s exposures. Credit: Tom Cuccia
Once again, the guiding was impeccable.
I’d like to also add the one big improvement from the AM5 to the AM5N is that there is wiring through the saddle. Now there is not one single wire I had last night coming from the saddle to the floor. The USB controlling the mount and the power for the ASI AIR both come right from under the telescope, greatly minimizing any possibility of snagging.
The Cocoon Nebula (Caldwell 19), in Cygnus. Integration: 67 x 300s exposures. Credit: Tom Cuccia
Shown is the latest update of the Cocoon Nebula. About 5.5 hours’ worth over 3 nights. I was thinking of adding some more but the improvement is starting to seem negligible. I’m happy with it. Loving that I’m now able to shoot reliably at a 2,000mm focal length with 5-minute subs.
Taken with the AM5N mount, Meade 8″ F10 (2,000mm Focal Length), Askar Colour Magic H-alpha Oxygen-3 filter. Camera: ASI 2600mc duo (duo for the autoguiding).
One note: you should try and balance the declination axis. Since there is no clutch to loosen, you kind of have to figure it out beforehand. For my setup, I placed the dovetail plate with scope camera and accessories connected on top of a magic marker and rolled it back and forth until I got a good feel for the center point. I made a mark on the dovetail plate where the center seemed to be and made sure that was centered on the mount. Not sure how important this is and what happens when you are outrageously off balance.
Now where to place the counterweight on the bar for when I load up the mount? Not exactly sure. Will cross that bridge if I ever get to it. Even if I combine my multiple setups in some dual dovetail configuration, I believe I will still be underweight for the counterweight requirement.
Tom Cuccia is a member of the AAA Astrophotography group.
