Guider work, assorted sub-projects at Year's End / Year's Beginning. . .

December 28.

Back from the Corcoran exhibit at Charlotte's Mint Museum of Art earlier than expected and under a beautiful evening sky. I really didn't want to set up the whole outfit with rain in tomorrow's forecast, but neither did I want to throw away the whole night. So I did some guider work. The ST80 has been giving me triangular guide stars ever since I first put a CCD behind it. Turns out to be a known problem and pretty much what you'd guess: strain on the lens from the retaining ring. After a substantial fight, I pursuaded the ring to come off. I cleaned all 4 lens surfaces while I was at it, replaced one missing spacer with the corner of a postage stamp (it's traditional), put the ring back on properly, and then took it outside. Images looked nice and clean through a 20mm Plossl, which is hardly challenging. I set it up on the G11 with a 0.5x Antares focal reducer and no diagonal. I wanted to make sure the guider would reach focus at this FL. It does, and feels really solid without the diagonal in the lightpath. Its PSF is no longer a three-lobed triangular mess, which should help with guiding at any FL and especially at just 200mm. It focusses well, is solid... I expect we can do effective guiding and that it will serve as a finder for the CCD behind the A-P.

December 29. I seem to be dreaming up a scheme to save weight and permit two ota's to be guided simultaneously or to mount and guide the SN10. Film at eleven... In an unrelated development, I broke the power attachment to the USB/PCMCA adapter while messing with packing arrangements <sigh>, a (better) replacement is on the way. I downloaded and installed a copy of the GSC to put the Pinpoint Astrometry modules of Maxim to work. Do they ever! Impressive software.

December 31. Astronomical projects to be thinking of over the first several weeks of the new year, in no particular order: a) optimize the 0.75x telecompressor spacing, b) solidify the CCD mounting hardware, c) build or buy the parts to put a camera or cameras on the SN10 (keep in mind that a Baader MPCC may be required, especially with the 20D), d) provide for mounting the guidescope on the G11's counterweight shaft – if it proves practical, this would reduce weight and increase portability and versatility, e) finish the micrometer focus adapter for the refractor, f) find out once and for all if I can get my wifi to reach the cul de sac -- there's a lot of sky waiting up there.

How? a) use an A-P adapter, b) use a new T-adapter, c) use part of an old Novak helical focusser and the Feathertouch adapter, d) damn it -- I overlooked something basic and simple and important, so just nevermind! e) wait for the proper drill bits then finish milling the parts, f) just carry the notebook up there and see if it sees my wifi network; if not, break out the reflectors, else plan on letting it run unattended.

Jan 1. Bought a piece of hex brass lathe stock for item d). Perfect! Now to find a 1.25-inch drill bit for less than 1.25 arms and legs. OK, I found one. Not that it matters, because, as I said, I overlooked something ridiculously fundamental. I'll do something else with the metal and the drill.

 

1.875" hex brass, 1.25-inch drill bit.
A little ambitious on this lathe.

 

A 3/4 inch bit works great.

 

Turning on the back of the toolpost to enlarge the
3/4-inch pilot hole to 1.25 inches. This is going to
end up a toe-saver and counterweight shaft
extension. Nevermind what it started out to be.

 

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Text & Photos by David Cortner
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