Archive for February 10, 2018

Visual Observing with a 6-inch f/6 Imaging Reflector Telescope: Is Sirius B possible With This Scope?

February 10, 2018

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The above photo of my now “prized” telescope.  I’m sure this scope is going to see a lot of use this year, and beyond.    Roger Ivester 

One of my desires has always been to bring back the excitement of the glory days of amateur astronomy, when all kids wanted a telescope.  The nights of the solitary observer in the backyard, attempting to locate and observe several of the showpiece Messier objects.

Those were the days for sure.  I wish it were possible to go back.  However, each and every night when I’m out in my backyard with my telescope….I become 13 years old again.  What a great feeling!

Now sharing my excitement from last night in North Carolina:  February 8th 2018

Yesterday, I received an email from observer’s challenge contributor, and email communications friend, Mike McCabe from Massachusetts.  He was very excited as he was finally able to see the companion to Sirius, known as Sirius B or “the pup.”

Mike was using an 8-inch reflector.  His excitement reminded me of my own several years ago when I was able (after ~40 years) to finally see “the pup” using a 102 mm f/9.8 refractor.  

Mike’s success in seeing Sirius B, caused me to want to know if it would be possible to achieve the same using my one year old, 6-inch f/6 (OTA) imaging reflector.  Due to working with my other telescopes, I’ve just not spent much time with this scope.

Last night I made my attempt (February 8th 2018) with the 6-inch to see if the companion to Sirius would be possible with this telescope.   The weather was perfect, 35º and totally calm. When I took my first look at Sirius, I knew that seeing was very good.

I started with 150x, but to no avail and worked my up to 232x, and there it was, but was unable to hold it constantly.  After more than 30 minutes with Sirius, I decided to attempt another challenge.

I then moved to the Trapezium in the center of the Orion Nebula. Starting with 232x, I was amazed how easy it was to see the E and F stars. There were beautiful airy disc surrounding the primary four Trapezium stars.  The beauty of a multiple or double star doesn’t get any better than this!

When I purchased the the 6-inch f/6 imaging reflector, I had no idea of the quality, either mechanically or optically.

However, I found out pretty fast, as star diffraction rings were “almost” identical when defocusing a star, in and out of focus.  After selling my Criterion RV-6, almost 40 years ago, I just wanted another 6-inch reflector, but not an f/8.

The humble optical tube assembly:  TPO brand, made in Taiwan, purchased from OPT in California, 2-inch focuser and also included tube rings.

The cost of the entire OTA was good also, only $199, not including shipping.  I don’t remember my old Criterion RV-6 being anywhere near this good, optically or mechanically.

I added an 8 x 50 finder, as it came with a tiny 6 x 30.  Not relative to the telescope, but I had to purchase another Vixen counter weight for my 20 year old GP mount, which is not pictured in the photo.

My primary reason for purchasing this scope was for portability and ease of carrying and set-up.  My 10-inch EQ reflector seems to get heavier with the passing of each and every year.

I never really expected such a quality 6-inch OTA for such an extremely low price.  This would show that sometimes you can actually get more than what you paid for.    Roger Ivester

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