Location: Chemistry/Physics Building, MUN
Time: 8:00 pm
Chris noted a few new faces, some of which were members of other Centres.
Clouds. Tim Caruk took some pictures of Saturn. Chris noted there was a solar mass ejecta this morning on the far side of the sun (some pictures from http://www.spaceweather.com). Fred has viewed Jupiter.
Robert brought us to a good site to determine what's up in the next month: http://www.skyhound.com. There are lists of what is good to view each month, from the point of view of a beginner, intermediate, or advanced observer. Charts will show views typical of a 6-inch scope and eyepiece, which is probably the best assumption to make (too many sites are based on larger instruments, especially when they discuss deep sky objects). There are sections for transient events, such as comets. We had a look at comet Maccholtz, which is still visible!
The President will be down to visit and give us a talk (observing in Hawaii, most likely) on Thursday, April 21. Members should note this is one day later than our normal meeting date!
Garry Dymond and David Caruk spoke on the upgrades David has graciously created for various of Garry's scopes. He brought along the mounting for Garry's scopes, and Garry had a presentation with many good pictures to show various stages of the work.
Garry has in the last few years acquired a Meade 60 mm (Rich Field). This is one of the plastic GOTO scopes from the Price Club (about $257). He also bought a 4-inch Maksutov from David. It would be nice if there were one mount for these two scopes, not as flimsy as the plastic mount. David examined the situation and decided he could take the original GOTO electronics and put them in a mount and housings of his own creation. It would have the advantages of being less flimsy, steadier, and the ability to handle either scope by sliding either one onto an attachment.
David showed us some pictures of his drill press and lathe. Other than some plastic GOTO parts that were reused, most materials were gotten from scrap metal dealers around town, and fashioned in his basement workshop.
They showed us some pictures of Jupiter and Saturn from the new mount, and according to Garry, once the GOTO locks onto an object, the tracking is excellent.
David is also working on fitting an 8-inch scope into a 10-inch GOTO mount. So far he has a circle of aluminum and a bar from a Nexstar 8, that should be able to be adapted into the larger mount, whilst holding the smaller scope. In addition, he has made an equatorial wedge, adjustable from 43-50 degrees latitude.
David also has a great interest in wide field, short focal length refractors. He has scoured the optical second hand markets for various pieces, and tried them out in different configurations. Finally, he has hit upon a combination and a design that works well. David took us through a brief tour of optics, including spherical aberration and chromatic aberration, and showed how different types of lenses can suffer from these problems. By combining two or more lenses, he can correct for these problems, and through over 20 years of experience in the field, he combined seven elements he acquired. The first is a 6-inch meniscus lens, ordinarily very expensive, but relatively cheap from surplus television gear. This lens by itself is not that great, so he added the extra elements to correct aberrations, and bring the focal length down to F 2.5. You would typically have to do this for most television gear, as it was not designed with astronomy in mind. David made a metal tube/housing for all these elements, and as we have come to expect, it was jaw-droppingly well done (it looks like a telephoto on steroids).
There were some pictures to demonstrate the meniscus lens (one lens, uncorrected), which were a bit blurry, with colour fringes. The final assembly was also demonstrated, with nary a color fringe to be seen.
Also for the future: a 9-inch F 1.8 refractor.
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