Monday, October 27, 2014

Say Hello To My Leetle Friend…My Astro-Tech 12" Truss Ritchey-Chretien Astrograph

My new 12" Astro-Tech 12" Ritchey-Chretien Astrograph with a Starlight Industries 3" focuser ready for collimation
Summer is gone and Fall has finally arrived in Florida. I've been chomping at the bit to get to Chiefland, Florida since May where I am fortunate enough to have a dome observatory to continue my astrophotography efforts. In June, I acquired a new telescope (actually an astrograph, i.e. a telescope that is specifically designed for astrophotography as opposed to observing) along with a slew of accessories to use this puppy but the heat and humidity had been a huge deterrent to making the two hour trip south to Chiefland to get my new baby into its home. This month's new moon weekend was just what I was waiting for - clear, cool nights. So, I  loaded up the car with the scope, the new/used Takahashi EM400 mount, the kitchen sink, and headed for Chiefland on Friday morning to get the new stuff installed.

Loaded up and headed for the observatory
Takahashi EM400 mount
Before I delve into the new telescope, I can't help making note of the Takahashi mount that I picked up to replace the Celestron CGEM mount I had been using. The EM-400 is a thing of beauty, the epitome of simplicity in a rock solid piece of hardware that purrs like a kitten as it slews and tracks. It's designed to accept up to 78 pounds of payload as compared to the Celestron that was only rated to 40 pounds. The Astro-Tech scope weighs in at 52 pounds so the Celestron mount was no longer an option. It was a great mount when used with my Takahashi TSA 102 4" refractor telescope but it wouldn't handle the 70 or so pounds of stuff I was going to use with the new setup - I'm planning on eventually mounting the Takahashi on top of the Astro-Tech (weighing in at 11 pounds) so that will take me to 63 pounds. A couple  of pounds for my SBIG ST8300 CCD camera, 4 pounds for the Orion Short Tube 80mm guide scope, a  pound for the auto guider camera, etc. and the EM-400 was just the ticket to get everything running.

Cutting 24 inches off the the 6" square steel pier so that the much bigger telescope would fit inside he dome
Once I arrived in Chiefland, we unloaded the Takahashi mount and did a quick installation on the steel pier inside my dome. We then unloaded the Ritchey and mounted it to see if there was going to be a clearance issue with the top of the dome - there was. The scope extended above the done by a good 12 inches. Not good. A few telephone calls later, I found a local welder with a mobile setup who was available to come to the property and remedy the problem.

The shortened pier with the mount installed
The solution was to cut 24 inches from the steel pier to shorten it, unweld the mounting plate from the top of the pier, and re-weld it on the shortened pier. Three hours later, the job was finished and the mount was reattached to the pier.

John, the Astro-Tech rep (left)  just happened to be spending the new moon weekend with us in Chiefland. Nothing like having the company rep to help me collimate the scope with a laser so the mirrors would be dead on in alignment
Back to the telescope installation - collimating the Ritchey before installing it. Not only am I lucky enough to have an observatory in one of the darkest places around, it sits on a friend's property right beside his roll off roof observatory. Also on the property is another friend's dome pod. So, when I go to Chiefland, I have two experienced, talented astrophotographers who are only too happy to help me walk through the astrophotography minefield. Bill and Tony have been engaged in astrophotography for years and both were on the property this weekend waiting for me to haul the new telescope down and help with installation. On top of that, since Bill's property is located within the Chiefland Astronomy Village, there are a host of accomplished astrophotographers within a rock's throw. Most of them stopped by during the day and assisted as we worked on the installation. The icing on the cake was that the rep for the telescope company that manufactured my new scope was visiting Bill and he had set up his gear in the middle of our observatory triangle. Nothing like having the manufacturer's rep on hand to make sure everything we were doing was perfect.  

After collimating the scope on the porch of Bill's roll off roof observatory it was time to carry the scope to its home in my dome (pictured in the background just to my right). Bill (left) guides us down the stairs as Tony (center) and I carry the scope to its new home
Weighing in at 52 pounds and some 3 feet in length, having some help moving the scope was a blessing. Bill (left) was the brains of the operation, Tony and I were the muscle 
Almost in the dome. Bill (right) kept the scope from bangong into the handrails
Maneuvering the scope onto the mount
The 12" Ritchey Chretien is going to take my astrophotography to a new level since it is specifically designed for just that purpose. In 1910, American optician and astronomer George Willis Ritchey and French astronomer Henri Chretien designed a specialized Cassegrain telescope that would later become the telescope of choice for many astrophotography observatories and professionals around the world. The Ritchey Chretien astrograph has many benefits that make this design appealing to anyone who is serious about imaging:
  1. Virtually no coma (coma makes stars look like little comets around the edges of the field), which means there will be greater image quality across a wider field of view;
  2. No chromatic aberrations, or false color; and
  3. No spherical aberration from the optical system.
The Astro-Tech 12" Ritchey has a 2432mm focal length with an aperture of f8. I installed a reducer that lessens the focal length a bit but the tradeoff is a faster aperture - f6 - and with a faster lens I'll have shorter exposure times. The focal length will allow me to get up close and personal with galaxies and other small, distant targets.

For wide field nebulas and planets, the Takahashi 4" refractor will still get lots of use and will be the perfect compliment to the Ritchey. The Takahashi has an 810mm focal length at f8, and with its reducer it's 610mm at f6.  It remains one of the best general purpose telescopes for planetary high-resolution observation as well as deep sky, wide field imaging. 

Installing the sock over the carbon trusses to minimize dust on the mirrors
By dark, I had the bulk of the installation finished. I still had the finderscope, auto guider, and camera left to install, not to mention running all the cables from/to the mount, scopes and computer plus getting the computer talking to all the devices. I also had to polar align the mount once Polaris rose in the night sky. All that was left for after dinner.

CCD camera, guidescope, auto guider, cables and power supplies all installed and ready for testing 
After dinner, I balanced the scope with the counter weights, mounted the guidescope, installed the auto guider camera, got the guidescope camera talking to the computer and the mount, and installed the CCD camera on the Ritchey's focuser. Tony has an EM-400 mount and came over from his pod to help me polar align the mount. I was blown away by how easy Takahashi makes this process. So far so good.

Unfortunately, after getting all the power supplies installed, cables plugged in, and otherwise being ready for an imaging test run, I ran into a snag. The old XP Hewlett Packard desktop that I'd been using for astrophotography went into USB hell. Monitors started losing signal and other USB devices were being intermittently recognized. The result was that neither the computer nor the software would recognize the existence of the CCD camera. "No connection" was the message I would get time and time again. After painstakingly trying to diagnose the problem, I tried plugging the camera into a friend's Windows 7 laptop and the camera worked fine. After several additional but futile efforts to reboot, reinstall drivers, etc. on my desktop, I gave up. Obviously the old XP computer had reached the end of its life and it was time to put it out to pasture.

Other than the computer glitch that prevented the old desktop from recognizing the CCD camera, I'm very close to being able to image with the new setup. My next visit to Chiefland will be in November for the new moon at which time I'll install the Takahashi refractor on top of the Ritchey. I have already tested the CCD camera on a Windows 8 laptop I had at hove and it worked as it always has. I'll be taking the laptop down with me to replace the desktop as my astrophotography computer. Come November, with 2 scopes polar aligned and ready for imaging, I hope to capture more of the heavens above.

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