Newsletter of the Desert Foothills Astronomy Club
Issue #17: October 5th, 2007
About Quid Novi
State of DFAC
Quote of the Month
Contact the Editor: Dan Heim, phone: 623.465.7307 or email:
|DFAC Events for 2007-2008:|
|Sep 26||7:00 pm - 9:00 pm||DFAC Lecture Meeting #1||Boulder Creek High School, 40404 North Gavilan Peak Parkway, Anthem, AZ 85086|
|Oct 31||7:00 pm - 9:00 pm||DFAC Lecture Meeting #2||Boulder Creek High School, 40404 North Gavilan Peak Parkway, Anthem, AZ 85086|
|Nov 3-4||2:00 pm - overnight||A Night Under the Stars||Alamo State Park (read more below)|
|Nov 28||7:00 pm - 9:00 pm||DFAC Lecture Meeting #3||Boulder Creek High School, 40404 North Gavilan Peak Parkway, Anthem, AZ 85086|
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|State of DFAC: By Dan Heim, President|
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|Last Meeting: Wednesday, September 26th, 2007|
|Our first DFAC meeting of the
2007-2008 season featured President Dan Heim speaking on
the topic of light pollution reduction (LPR). In addition
to the usual informational content provided (which is the
standard LPR lecture given to other groups), he updated
the membership on activities and developments since last
year's opening meeting on the same topic. As explained
above, this opening meeting on LPR will be a DFAC
tradition given our intrinsic interest in the topic.
Dan reported on the following developments of LPR interest:
As you can see by the comprehensive list, we've been busy representing members' interests in many venues. Of particular interest was the last item, which Dan and Roger personally investigated. These experimental streetlights were installed as a joint project by the City of Phoenix Lighting Department and APS, to investigate performance and get local residents' feedback. The lights are located along two culs-de-sac at 63rd Avenue and El Cortez (just north of Happy Valley Road). Here's two of the streetlight spectra photographed by Dan and Roger. Note that we used only a diffraction grating placed over the camera lens. Without a narrow slit to admit the source light, one gets significant overlap between parts of the spectra and reduced resolution. We're working on a revised camera adapter to include such a slit for future use. Still, one can easily see the color of the light sources from this first crude attempt.
Both light sources appeared very "white" to the eye. The spectra confirm both sources are well balanced with no excess of blue/violet (which is the bane of astronomy and one of the reasons mercury vapor lights are being phased out). We're all familiar with LEDs, and the first generation of "white" LEDs were significantly bluer, as the next spectrum clearly shows. This spectrum, by the way, was photographed through an improvised narrow slit (using the same diffraction grating) under better controlled conditions:
We have endorsed these new LED lights on the basis of their balanced spectrum and high efficiency. Communications with the City of Phoenix and APS are ongoing. The induction lights use an RF oscillator to directly stimulate a low-pressure gas into emission. Standard LPS, HPS, and fluorescents use a high-voltage arc to stimulate the gas, resulting in a few strong emission lines in the blue-to-violet range. Although the induction spectrum we photographed seems well balanced, we'll take another look once we have the higher resolution camera system perfected.
Attendance at this first meeting was 10 members and two guests (who read our meeting promo in the Foothills Focus). The expected BCHS students were conspicuously absent, we suspect due to this still being "the start of the school year" when things are quite busy for faculty and their charges. Other DFAC members may also have passed on this one expecting the same lecture as last year. I regret that we didn't emphasize the "update" nature of this presentation in the last Quid Novi. The meeting adjourned at 9:00 pm.
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|Next Meeting: Wednesday, October 31st, 2007|
|Our October Lecture features local amateur Gene Lucas of SAC. Gene's been a fixture in Valley astronomy for decades, and will share his insights on binocular astronomy, as well as his collection of some 19 different binocular models (including a vintage Japanese periscope binocular system). If you've ever thought that binoculars were just for beginners, come and learn why you're wrong.|
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|Quote of the Month:|
first introduced to the public over a century ago in a
book written by an Oxford mathematician. Perhaps
realizing that adults might frown on the idea of multiply
connected spaces, he wrote the book under a pseudonym and
wrote it for children. His name was Charles Dodgson, his
psedonym was Lewis Carroll, and the book was Through The
Physicist Michio Kaku, "Visions - How science will revolutionize the 21st century"
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|A visit to Conley Observatory:
Well, I don't know if that's its official name. Jim never mentioned. And I didn't ask. But last week I took up DFAC member Jim Conley's long-standing invitation to stop by and see the observatory he's built in his backyard just south of the Carefree Highway. It's a unique and clever design, as you'll see from the pics ...
As you can see, there's no dome. Only what appears to be a trailor lid capping it off. In fact, it is a section of a fiberglass trailer lid originally destined for the landfill, but Jim got it for free. One end was damaged in an accident, so he just cut that end off and sealed the opening with wood. The stucco finish was required to make the decor match his home. It's not a large building (about 8x10) but sufficient to house the equipment he uses.
Here's a view of the back (north) wall of Jim's observatory, showing the unique mechanical system that literally lifts the roof. He designed and built this system himself. The roof rolls and tilts along those horizontal tracks, pulled by both the counterweights (visible at far left) and a hand-operated winch visible at the middle of the wall.
This is a closer view of that winch system. I tried it myself, and the gearing makes it a snap to use.
But this is the really clever part, in my humble opinion. The white pipe (there's one on each side) levers up as the roof is pulled back, lifting the roof off its rubber gasket and moving it back along the track. It's all standard plumbing pipe, available at your favorite hardware store.
Here we see the observatory fully open and ready for business. We didn't do any observing, as I had come early enough to get these photos in daylight, but Jim says he'd be happy to host an observing session at his place (your scope or his). Trust that we'll be taking you up on that, Jim.
Inside the observatory Jim has all the usual amenities for astronomy. I especially liked the wall-switched red and white light sources, hanging now, but mobile for convenience. The circumference of the interior is lined with a string of red mini-lights for additional low-level illumination.
Opening the wiring panel reveals all the cabling required to make this thing run. There's a data cable destined to run to his home office, but it's not yet connected.
One more nice detail, photographed before we lifted the roof, is a locking pin to hold the roof against microbursts or other wild winds. Jim added these after a particularly windy evening when he discovered the roof had become partially dislodged. There are three of these pins for added security.
These last two images show the main hardware. That's a Celestron C-14 (f/11, 3910 mm) with a Burgess 5" refractor (f/8, 1000 mm) as a finder. They're tandem mounted on a Cassidy bar, and ride an Astrophysics 1200 go-to mount. Very impressive array of instruments. I look forward to seeing it in action after dark. Thanks to member Jim Conley for the personal tour and photo op. Now we just need to schedule our club night at Conley Observatory.
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