Newsletter of the Desert Foothills Astronomy Club
Issue #17: October 5th, 2007


About Quid Novi

Past Issues

DFAC Events

State of DFAC

Last Meeting

Next Meeting

Quote of the Month

Space Debris

Contact the Editor: Dan Heim, phone: 623.465.7307 or email:


DFAC Events for 2007-2008:
Date   Time   Event   Location
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

Back to Top

State of DFAC: By Dan Heim, President
  • Lecture Series Update: We now have all but one date (March 26th) for our 2007-2008 Lecture Series booked! See the schedule here. I've got a few ideas for that last slot, some received from members. This date is a ways off, so no huge rush, but if you have any suggestions for a speaker on that date, let me know. We want our Lecture Series to reflect member interests as well as general public interests ... in fact, more so. Thanks to those who have provided input.
  • New Tradition: After initial discussion by Roger and I, and member discussion at our last meeting, we've decided that the first lecture of our season, every year, will be on the topic of "Light Pollution," including an update on DFAC's ongoing LPR (light pollution reduction) efforts. After all, that was one of the main reasons we formed this organization. As I pointed out last issue, this would be my annual contribution to the DFAC Lecture Series. The issue of light pollution won't go away and, as attendance at our meetings grows, it provides a public forum to help get the word out. Furthermore, it gives us an opportunity to "shake down" our meeting facility before any guest speakers arrive ... you never know what happens to a school room over the Summer. In fact, at our September meeting, we discovered BCHS had fixed the vibrating projector problem by installing a new ceiling mount. They also bypassed the always-on fluorescent fixture (which we had been manually unscrewing) above the projection screen. Very nice. Now I can leave my projector in the car (but I always like to have a spare along just in case we need it).
  • LPR Update Update: No, that isn't a typo. This is an update to the update I presented last meeting. Member Scott Loucks provided me with some contacts at his company, which does work for ADOT, and I got a callback from ADOT's lighting department. Here's what I found out about the I-17 upgrade project. They will be running median lighting all the way from PHX to the Carefree Highway, with standard 100-120 foot spacing. These lights will be high-pressure sodium vapor (HPS) and fully shielded. At the interchanges, lighting will also be HPS, numbers and heights pending layout of those interchanges. When I asked about low-pressure sodium vapor (LPS) I was informed that engineering studies have shown the installation costs are higher due to the greater number of lights (and/or larger wattages) needed to provide the required illumination at street level, and that the energy costs to operate these extra fixtures outweighed the slight difference in efficiency between LPS and HPS. When I asked about the LPS I've seen on other interstate highways around the country, I was informed that I wouldn't be seeing them much longer, as this was a national trend in lighting departments at all government levels. When I asked how Tucson and Flagstaff seemed to be making LPS work, a harsh reality was explained to me — where professional astronomy is at stake, LPS is considered an economic alternative. Unfortunately, not so for amateur astronomy. So that's where we are now, which brings me to my next topic ...
  • LPR Strategy for DFAC: This first year has been educational for me. Scott Loucks' comments (at our last meeting) about the LPR impact of my weekly Sky Lights column were appreciated, but that kind of impact is hard to measure. I want DFAC to have a real and measurable impact on LPR in the north Valley. And I need your input on where to best focus our efforts. Over the last year I learned much, made several important contacts at all levels of government, and provided input to whoever would listen. That's good for the first year, but now we need to make something happen. I'll be distributing copies of the lighting ordinances at our October meeting. I want all members to familiarize themselves with the code, think about where we might be effective in changing it (if at all), and suggest a strategy for the future. I have my own ideas, of course, but I want your input too. We can take some time at the start of our next few meetings for discussion, but no more than 15 minutes in deference to our speakers. Better for now to provide your input on this issue via email or phone, any time.
  • Alamo State Park Astronomy Night: DFAC has received an invitation to a "Night Under the Stars" at Alamo State Park northwest of Wickenburg, Saturday, November 3rd. You can download a copy of what I received here (601k PDF). Roger and I are considering attending. Since they prefer reservations to be made on a "club basis," let me know if you're interested no later than October 12th. This looks like a fun event in a really dark environment.
  • Thanks for reading Quid Novi. You know where to send your feedback. Until we meet again, clear skies!

Back to Top

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:

  • Carefree Highway Scenic Corridor development plan
  • New River Road corridor development plan
  • Black Canyon Motorplex (assisting the NRDHCA in their parallel efforts)
  • I-17 upgrade project
  • Arroyo Grande development (west of I-17 near New River)
  • City of Glendale LPS streetlight removal
  • City of Phoenix experimental LED and induction streetlight project

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.


LED streetlight spectrum


Induction streetlight spectrum

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.

Back to Top

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.

Back to Top

Quote of the Month:
"Wormholes were 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 Looking Glass."

— Physicist Michio Kaku, "Visions - How science will revolutionize the 21st century"

Back to Top

Space Debris:
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.

Back to Top