Considering that our course offerings cover the full range of classical mechanics, it should come as no surprise that we have many, many objects useful for demonstrating motion. Balls, cylinders, carts with low friction, blocks with high friction, carts which glide, carts which propel themselves, carts students can ride, etc. Also, just in case: a Jurassic Park-branded pickup truck.
It comes with a driver – currently leaning to their right, as if to call to someone on the passenger side of the vehicle – and a cage for the lion velociraptor. Complete with said velociraptor in the back.
For the most part, the light accumulation of dust, pollen, and other stuff on the objective lens of your telescope is a thing you live with and ignore. The damage you can do to the lens and its optical coatings is far more severe than the minor loss of image quality from tiny flecks. Known and accepted trade-off.
Here, however, we have a classic TeleVue Renaissance that’s still in good shape. Aside from the dust and dead spiders, anyway. Exact age is unclear, but we can roughly place it between TeleVue’s founding in 1977 and the construction of the “Halley’s Comet” models in 1985. Serial number 1100, for anyone keeping track at home. Even dust-covered, the optics appear good at a quick glance, and they have a reputation for remaining in good shape for a long time.
There’s a bit of chromatic aberration when you look closely, an issue which has been resolved in their current models. (Optics = hard.) The design type is called a Nagler-Petzval, which uses a pair of lens doublets to correct numerous distortions caused by refraction. Every design has its pros and cons; this one’s quite nice. Our version has – we think – an air-spaced doublet (two lenses utilizing different curvatures) as the objective, and a cemented doublet in the rear.
At least, that how the Halley’s Comet edition was made. The current optics update utilizes two air-spaced doublets – see the diagram for the NP101is – so it’s reassuring to see that the improvements are incremental. Good sign for the one we have.
Okay, the brass could’ve aged better, but it’s got character!
Needs polish.
Black on brass looks good.
Nice touch.
Even the knurled knobs on the focuser are brass. We don’t want to leave this for display, however. We want to see the stars!
Eesh.
That dust, though.
Speckly.
Yeah, definitely a problem. A cleaning is in order.
Can’t make it worse, right?
Not pictured: the dead spiders removed with air from a bulb blower. Dead spiders do not improve optical quality.
Red goo.
Here, we’re applying a coat of First Contact polymer cleaner, an expensive but effective treatment for safely removing gunk from precision optics. Comes in a wee bottle like it’s nail polish and smell like nail polish remover. Because it’s got acetone and other solvents in it.
Drying before removal.
Once it dries, that little tab lets us pull away the pink film with all of the dust and debris stuck in it. A good time to wander away from the stink of volatile solvents and get a cup of coffee.
Much improved.
And, well, that’s a substantial improvement.
Water spots. No dust.
It’s not perfect. The polymer is very good at removing particulates, but less so at water-soluble stuff. Once we evaluate this with a camera setup, we can see if a follow-up cleaning with deionized water is necessary.
Big improvement.
Problem there, of course, is that we run the risk of introducing tiny scratches in the process. Could be worthwhile if the effects are still visible, but we’re still erring on the “do a minimum of harm” side of things.
Despeckled.
Will it live up to its potential as an imaging ‘scope? Maybe. There’s a fair chance. If not, we’ll keep it around as a stylish yet usable throwback for visual observation. The best telescope, as they say, is the one you use.
You can’t tell from the photo, but the tone is lovely.
Both Physics and Astronomy courses do a lot of work with waves, and while light is one of the most important types for study, sound is exceptionally handy for demonstrations. There’s an immediacy, a feel, that can make sonic demos feel more intuitive.
We have a few of these about, metal bars with supports at the nodes of a standing wave, seated over a wooden box. The string goes where the bar doesn’t vibrate, and hence doesn’t dampen the sound, while the box helps it resonate louder. Ka-bong! They’re quite fun.
Quality!
And, yes, Carl J. Ulrich of Minneapolis, Minnesota did some fine work here.
As one might imagine, hundreds of students in labs each semester means we use a lot of batteries. Just a ton of ’em.
Sometimes we need them at full capacity, but certain uses can be fine if they’ve started to develop some of that internal resistance after a while. Certain situations call for the higher potential current output of alkalines, while others need lithiums to keep the voltage from dropping too low. And at other times, the relative calm of a zinc-carbon battery is just perfect, like when students are building basic circuits and there’s a risk of shorting the batteries.
Much lower risk of booms and burns with the zinc-carbon.
Still, unless a battery’s in real rough shape, you never know how much juice they’ve got left just by looking. Pop one on the tester to see. When they’re almost new, you can hear the needle tap the far side!
In 1991, the Astronomy Club had clearly grown tired of plain walls at the Observatory. With a fantastic mural adorning the interior stairwell to access the Clark telescope (subjects of future posts!), the regular hallways must have looked… fine.
Prof. Dave Lien was the faculty member overseeing all of this, and in April the club had decided a scale version of the solar system would look pretty great. Time to check in with the Art folks!
(Also: “Observing, etc.”)
Just a few-AU-long stretch.
And you know what? It’s way better than white walls! The final design ended up being different from the proposed idea, though the concept is the same. The Sun occupies a place of prominence, and the mural includes both scaled sizes and scaled distances of our solar system, shown side by side.
Not both at once: in that case, it either wouldn’t fit in the building or the planets would be so tiny you couldn’t see them. Both of which really defeat the purpose. (Not that they aren’t fun demonstrations in their own right!)
January, 1997.
Five and a half years later, ta-da! After a quarter-century, several building repaintings and a recent renovation, it still looks sharp.
FOR RELEASE: February 1, 1971; FOR KEEPSIES: In Perpetuity
Do you ever set aside some papers, because you don’t need them right now, but they were maybe interesting for later? And then eventually there’s just a pile or folder or shelf devoted to these, because you’ve inadvertently started a collection? And then, half a century later, someone stumbles across these boxes and wonders, why?
Why do we have boxes of printed press releases from NASA in the early 1970s? Probably the same reason we have old math exams from the 1940s out at the Observatory. (That’s a post for another time!)
Honestly, if we’d been diligent about tidying this stuff, this blog would be way less interesting.
