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First Light On a 2021 18" Obsession f/4.2 Ostahowski UC

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#51 Kunama


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Posted 17 August 2021 - 11:45 PM

Strange times call for changes in one's activities. Since the pandemic, my activities had been mostly limited to golf, autocrossing, motorcycling, hanging around the house reading with my wife, and exercising. Then, an almost new 18" f/4.2 Ostahowski-mirrored UC pops up on the radar and after the umteenth time trying to leave the hobby, I happily got sucked in once again. Last night, in West Central Florida, the Clear Sky Clock finally showed anticipated great skies and it was time to test out the UC=Ultra Compact Obsession.


This latest iteration of this UC is not your grandfather's original UC that used a seat belt sling and did not have lateral stiffeners for the hinged altitude bearings of the Virtual Mirror Box. This scope came equipped with a fabulous, very high Strehl Ostahowski primary mirror, coated cable sling and the above-mentioned altitude bearing stiffeners. Upon getting the scope, I spent several full days just reading the operator's manual, adjusting various components and digesting as many of the nuances in the design as my non-engineer brain could absorb. I must say that Dr. Kriege's latest iteration, based on ease of transport, lifting and use is frankly a home run. I can see why he finally migrated away from his beloved and venerable Classic Obsession with their conventional mirror boxes and rocker boxes. Given the design goals of lighter weight and ease in transporting in smaller vehicles, the UC is less rigid than the Classic but has very acceptable damping times on the order of about 2 seconds without a ServoCAT drive which would make the scope track more rigidly. 


I had rolled the scope out of my air conditioned house before sunset and left my microfiber towels on the face of the primary mirror and left covered with the mirror cover to let it thermally equilibrate with the steady Florida temps. By the time I had set it ready to view, the primary/secondary was apparently fully equilibrated because the views through my 21mm Ethos in my Paracorr 2 were showing perfectly round, pinpoint stars after I had completed a final tweak of the collimation. I had to use the Ethos 21 to dial in the Telrad 1x finder and the 50mm Stellarvue correct image visual finder. The Summer Triangle was up and I used Lyra to get the finders aligned and then moved the scope to the Double Double in the Lyra constellation. The stars were already pretty pinpoint and I was able to use a 13mm Ethos to comfortably view the 4 stars at 169x. I then pointed the scope to Albireo, the absolutely beautiful contrasting two very colorful stars also at 169x. The seeing was not fully supporting my 6mm Ethos at 365x. 


Now that I had things working well, it was time to go to M4 and M80 in Scorpious and later to return to Sagittarius and the surrounding area of the Milky Way to see some old favorites including some pinpoint open clusters and double stars with my 21mm and 13mm Ethos ep's. I had earlier taken a peek at Saturn as it was rising and the views were sharp at 169x with lots of detail. While staying dark adapted, I cruised around without an OIII filter to known nebulae and could barely make out some of the targets with the Swan (M17) being most prominent without a filter that I need to buy. 


As always, part of the magic of the night was viewing Saturn and then Jupiter as they rose higher in the sky at about almost 11 p.m. last night. The rings of Saturn are slowing closing up since being fully open in 2017 and are about half way to edge-on in 2025. Jupiter and the Jovian Moons were looking good at 169x and the GRS was rotating into view. I had some lucky views with my 6mm Ethos at 365x but the seeing would rarely support the magnification so I stuck to the 13mm Ethos. Sadly, I only had about 1 hour on the planets before the seeing went from about 8/10 to about 6/10 and I ended my session at a few minutes before midnight. By that time, the Milky Way above the house was pretty much faded out and the air mass had become more humid.


Some thoughts on the UC and especially the Terry Ostahowski primary mirror. In terms of transport, the VMB=Virtual Mirror Box that Kriege has designed makes the scope soooo much easier to transport to darker skies. At age 72, I can almost comfortably lift the VMB into my car by myself. The rocker platform only weighs 7 pounds. With the use of the wheelbarrow handles, the scope fully assembled seems to only weigh about 10 pounds and I can literally lift the handles with one finger of each hand. The 6-truss pole system is fully attached and so assembly of the scope is relatively straight forward once you learn the little tricks on how to manipulate the components for ease of assembly. There is relatively little shift of the laser from 30-80 degrees of movement of the scope and the laser remains somewhere in the center spot donut throughout the arc. I already addressed the damping times and with Ethos ep's, you don't need to be perturbing the telescope as often to keep it on target so the views are generally very stable as the target moves through the eyelens.


In summation for first light, all I can say is that I am VERY happy that I bought this scope. I did not use the 32k encoders and the Argo Navis last night but they will help me get to all of the DSO's I want to revisit from almost 20 years in the hobby. As I am aging out, it represents a very functional and pleasant large aperture scope that does not have all of the attendant limitations of a conventional Newtonian since it is so skeletonized. The relatively fast Ostahowski mirror with the Paracorr 2 and the Ethos ep's are a beautiful match with very bright, high contrasty sharp images produced. Finally, I have been in the process of reading all of Anthony Hillerman's Navajo Tribal Police mystery novels on my Kindle Paperwhite and a very strange thing occurred last night that caused me some pause. At about 10:30, I heard a very faint noise and rustling about 20 feet from me at the edge of my driveway and sensed I was being watched. I made a sort of barking sound and witnessed the shape of a coyote scamper away with the sound of his claws grabbing the concrete pavement. If I were a Native American, and specifically a Navajo, I would have wondered what the presence of the coyote meant? Thanks for putting up with such a long first light report. Bob Schilling

Great to see you back posting Bob.  Excellent report, sounds like a nice scope!

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