2011 Oregon Star Party Telescope Walkabout

Variety rules - OSP an effective deadline.

The telescopes on the walkabout represent a variety of designs, several being completed just in nick of time for the star party.

Greg Babcock's 20 inch f/3.5 all aluminum construction altazimuth telescope was built by Greg and Nate Courrier. One of the most interesting aspects of the design is the bridge that stabilizes the focuser board to a truss tube. The upper ring is designed to act as one of the baffles. The T-6061 aluminum parts were cut by a waterjet. The scope weights 115 pounds. The 65 pound mirror box slides out on a track, the mirror being 1 5/8 inch thick Pyrex made by Steve Swayze and supported by a 18 point flotation. The scope does not require a ladder to view at the zenith.The scope moves on ball bearings equipped with brakes to stiffen the motion. Greg always uses the new TeleVue P2 coma corrector while viewing.Greg plans on minor modifications for the future,.

Ian Morrison's 12.5 inch altazimuth is a single pole design, based on some of Ross Sackett's ideas. Ian found that the upper ring was too light so he replaced some of the Oak bottom components with lightened plywood. The upper ring is very light - just 1.5 pounds! Ian bent the aluminum for the upper ring one inch at a time then annealed the ring. The wire spider is made from stainless steel fishing line. He uses a 1.25 inch focuser to save weight. An old-fashioned hat box holds the upper ring for transport. The single arm is aluminum tubing which does not ring and dampens easily by touching it. He may upgrade the azimuth bearing by replacing the material that the Teflon glides on. The homemade mirror cell uses rare earth magnets to hold the cover. Mark Cowen of Obsidian Optics made the Quartz mirror of 6 pounds weight. Total weight is 30 pounds. Ian uses the encoders with an iPhone app for telescope positioning.

Serge Taran's 18 inch f/4.2 ultra compact altazimuth fits into a small hatchback car using fold up altitude rims, collapsing truss tubes that interconnect as a single unit and a carbon fiber upper end. The mirror is by Zambuto, supported by a sling with guides and the drive system is by ServoCat and Argo Navis. The scope has no welding: everything is bolted together. There's an aluminum spider. The initial upper ring wobbled a bit and he has ideas on improving the trusses such as making them from carbon fiber. The scope is shrouded, the zippered shrould being made by his girl friend, Mary. The overall weight is 75 pounds.This is Serge's first scope and he is taking it one step at a time.

Serge's images are located at http://www.pbase.com/staran/osp2011

Dan Gray's direct drive motor on his 14 inch scope uses no gears, no rollers and no reducers of any kind. In fact it has no moving parts. It's home made including the winding of the copper coils. The magnets are powerful rare earth types. The encoder feedback is a Renashaw optical encoder attached to the face of the azimuth ring. The drive system tracks at sub-arc second accuracy and can slew at 50 degrees per second, whipping the scope around in a frenzy. Leaning on the scope causes the drive system to recenter the scope quickly. Thus the drive system can compensate for wind gusts. Dan made an outstanding movie of comet Garradd the previous night using his drive system. His scope is fully motorized including the focuser and de-rotator. The altitude drive is more traditional roller based drive with a Gurley 320k encoder. The scope overall draws less power than the laptop that runs the software.

Jerry Oltien's super sized Astroscan is a ball scope with a tracking system. The scope is equipped with a 8 inch f/4/2 mirror that Jerry ground and figured. The ball is a rather unusual 20 inch diameter polycarbonate intended for pole lighting. He reinforced the ball with fiberglass laid internally, as opposed to externally covering the ball. The top cylinder is a garbage can that disconnects from the ball, the focuser from molded plastic with matching dust cap where the only difference is that it reads Jerry's name instead of Edmund. There is no optical window as in the original Astroscan so Jerry uses a curved spider to make the diffraction spikes invisible.Jerry uses a novel collimation tool inserted from the topside of the tube. Even the homemade eyepiece matches the design of the original Edmund Scientific RKE eyepieces. The scope gives outstanding views and tracks to boot, using a homemade very simple and inexpensive drive system. To use the scope, one points it at the object, orients the eyepiece to a comfortable angle and lets go of the telescope. The scope will track on the object all night long. The drive consists of two rollers and a motorized axle.