A telescope old and new

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No, it’s not a home-made pumpkin cannon.

Instead it’s a trap for photons.

Or more conventionally, it’s a fine astronomical telescope** made by a teenager named Stewart S about 50 years ago.

That’s the part inside the white metal tube.

The plywood box that looks a bit like a Civil War cannon is actually a fairly conventional Dobsonian-style plywood alt-az mount that I made over the past few gloriously clear days in the driveway of my house in Brookland (Northeast DC). #

Yes, that tube is LONG – over seven feet long. It’s finely welded aluminum plate, bent into a cylinder and formed by one of my predecessors in leading telescope-making classes in the DC area, Hoy Walls (whom I never met).

The plywood mount used almost all of a full four-feet-by-eight-feet sheet of 3/4″ hardwood plywood.

I was pleased to see that my calculations were all correct, so that the scope just barely fit inside the plywood pieces and that the mount as a whole behaves well. No filing or last-minute sanding was needed. And the balance is pretty good – all I needed to do was add an old three-pound Barbell-type weight to the front end – it’s the dangly thing near the flange in the front. Having that weight imbalance is actually a good thing, because it gives us leeway to add a small finder scope to help aim the scope at objects of interest.

The flange is actually a plywood ring that I cut with a router and a decent commercial template for circles. The plywood ring fit perfectly, which was gratifying. No sanding or filing was needed — a first! I added it because the front end of the tube had been banged up or pressed hard at some point and was no longer circular.

I made an adjustable clamp inside the scope that seems to be working quite well. One can loosen the clamp and then rotate the tube to make it easier for shorter people can reach the eyepiece. Or one can move the tube forward or backwards to fix any future balance changes. And then clamp the tube back into its new position.

The optics were in very good shape – very clean, not a bit of dust or insect debris, on a beautifully smooth and fully-polished out mirror. I checked the optics briefly with a Ronchi test, and found that it had no turned down edge (which is a good thing) on its surface. I did not have time to use the Couder-Foucault Zonal Knife Edge test to calculate how well-corrected the optics are. Correction is a technical term involving changing a near-sphere to a near-paraboloid by carefully removing less than 2 cubic millimeters of glass — all together — in just the right spots, over a period of weeks or months to try to reach perfection.&&

Since the scope is done, the normal final test is to try it out on Polaris or some other fairly bright star with a short-focal-length eyepiece, looking at the diffraction rings when you roll the eyepiece into and out of focus.

Which brings me to why I had to build or modify the mount that it came with.

The mount that Stewart and Hoy made and that Stewart donated to NCA was very, very heavy, being a classical example of a heavy-duty – modified – plumbing – and – automotive – parts style of telescope making that many amateurs used around 30 to 60 years ago, before John Dobson revolutionized amateur telescope making with his eponymous telescope mounts and his unusual mirror-making methods using cast-off naval portholes as substrates for mirrors.

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That’s me above on the right, wearing an Escher tessellation Y-shirt, at Almost Heaven Star Party near Spruce Knob, WVa, next to a green telescope I made with Nagesh K. It’s called a Lurie-Houghton telescope design because of the geometry of the lenses and the mirror. Bob B did most of the lathe work for the aluminum finder scope that Jan appears to be touching with his left hand. Unfortunately, this telescope is so far a complete and utter failure although all of the individual pieces seem OK or great. Until we figure out what went wrong, we are stuck in limbo. The mount, but not the scope design, is a Dobsonian.

 

 

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The late John Dobson visited our telescope-workshop once, perhaps 10 years ago. He is the oldest person in this picture, facing us, with a bright blue jaket and white hear. It looks like I am doing some sort of incantation over the mysterious batch of molten pitch, but it’s all scientific — no magic spells. *

Unfortunately, the mount on the long aluminum telescope as it came to us was impossible even to roll through doors and was incredibly heavy. We (Mike L, Bob B and I) tried to fix the wheels on the platform that held the mount (sorry, I can’t find any of the photos I took of it), but we then found that the scope literally would not hold still. As a result there was so much backlash that you could not aim it anything and actually look at the object for any length of time at all. I considered putting three jack-screws so that the platform could be jacked up (much the way cranes and RVs will jack themselves up off their wheels) to be stable, but I couldn’t think of any way that wouldn’t require an enormous amount of time or money.

I also wanted to see if I could make a Dob mount in about three days.

I did.

And it worked.

Right now, you can aim the 10-inch f/long scope at an object and the object will stay there in the finder except for the Earth’s rotation. The tube is reasonably well-balanced. With some muscle and the clamp I made, you can change the balance point. Unfortunately, the mount really could use a little bit of beefing up as far as the base is concerned, and I’m contemplating how to do that without adding too much weight.

Alan T helped me take out the guts of the telescope, wrestle the tube into the plywood mount, and then re-assemble the optics. We looked through it at Hopewell Observatory last night. The Moon, Mars, and Saturn were well placed and looked pretty good, and it seemed like the air was pretty stable. We did not crank up the magnification very far, and the Moon was so bright we all cast shadows on the grass, so very few stars and no Milky Way were visible. A formal star test will need to come later.

On behalf of National Capital Astronomers, I would again like to thank Stewart S for donating this fine telescope.

 

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# I hope my neighbors will forgive me. I didn’t work on it at night.

* Some of us amateur telescope mirrors will admit to uttering curses from time to time, but unlike what happens at Hogwarts, they never work. Guess we are just Muggles, condemned to obeying the laws of physics and the other sciences.***

** This scope is not my personal property, nor does it belong to the Hopewell Observatory in northern VA where this photo was taken and of which I’m a member and current president. The telescope tube and a different mount were donated by Stewart S to National Capital Astronomers and is currently housed at Hopewell as a service to NCA. Stewart is obviously no longer a teenager!

*** Actually, I’m rather glad that the laws of physics and other sciences don’t seem to be under the personal command of any individual, and that they seem to be exactly the same for all people and – as far as we can tell so far — everywhere else in the universe. (Yeah, I know that some astrophysicists and cosmologists make claims that certain basic constants of nature change in certain ways over time, but I’m reserving judgment on that. OTOH I hope I live long enough for someone to figure out what ‘dark matter’ is. It remains spooky and awesomely mysterious that with all of our current state of ever-expanding scientific knowledge, most astrophysicists still believe that the vast majority of the matter and energy in the universe is still completely unknown. We don’t know what it is. I find that the idea that the universe has immutable rules, many of which have not been discovered, much more comforting than having a universe where somebody else could get mad at you or me and change the laws of physics in your immediate vicinity with the purpose of doing us harm — and that all those powers are accessible by certain individuals who claim that they have been in personal communication with a personal deity, who uttered cryptic messages and incantations and rules that must never be questioned. How could powers like that NOT corrupt somebody?

 

&& like a small sand grain.

Published in: on June 8, 2014 at 9:17 pm  Comments (3)  
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An Astronomer Looks at the Zodiac

Or, has your “sun sign” changed after 2000 years?

And did you know that the Zodiac has at least 15 constellations?

This is a little presentation I did last week on the Zodiac for something called the “Encyclopedia Show“. Out of eight ‘acts’ in this cabaret show on “The ZODIACalypse!!!”at a place called The Dunes in Columbia Heights in DC, there were two musical selections, a few poems, a stand-up comic, an interview with a professional astrologer, and some rants and skits.

Most of the presenters (but not all) seemed to be quite skeptical about the many claims made by proponents of, shall I say, ‘traditional’ astrology. At some point the organizers will post a video of the night’s affair, as they have for other ones. Past shows seem pretty good and I may come back to watch more of them, in the future.

My role was as straight man, I guess, narrating a little powerpoint presentation using slides I gathered from many places, including a bunch of beautiful images from NASA’s wonderful  Astronomy Picture of the Day and other places. I actually got a lot of laughs and applause, and a bunch of folks came up and told me they really enjoyed my part. Some of my fellow-astronomer friends came and didn’t regret it either.  It was actually a lot of fun.

Here is the link to the PPT itself on Google Drive. Feel free to use or modify it as you like, and enjoy. And here is a link to a YouTube video of my talk.

NOTE: I see that I got the terms “equatorial plane” and “ecliptic” confused in my talk. “Ecliptic” is the apparent path of the sun through the heavens, i.e. along the Zodiac. The equatorial plane of the Earth is just that, a projection of the Earth’s equator into space. (These two planes are different, as I correctly noted; they form an angle of about 23.4 degrees to each other.) My bad.

image

Here is a slide so you can cut to the chase: what is your sign, really?

traditional and modern zodiacJust for fun, I did a search of the sun-signs of the 44 US presidents. You would think they would all be rather similar, right? Nope. Look for yourself:

presidents and sun signsHowever, that had to be cut from my presentation because it was already too long.

I also wanted to show a short video by magician James Randi where he debunks astrology 100%, but it, too, had to be cut. Here is the link:

Published in: on January 21, 2014 at 6:45 pm  Leave a Comment  
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Alien Civilizations on Mars Worshiped Piglets and Empanadas — Proof!

The Pig, Seahorse, and Jamaican Patty on Mars

Remember the ‘Face on Mars’ that was proof to some people (including at least one brilliant astronomer, believe it or not) that aliens who looked a lot like us made statues and monuments on mars that you could only see from above?

I HAVE PROOF NOW THAT THEY WERE WRONG. THE ALIENS DIDN’T NECESSARILY LOOK LIKE US. INSTEAD,they were probably  WERE MORE SIMILAR TO ONE OF THESE SACRED SYMBOLS:

(1) JAMAICAN BEEF OR GOAT PATTY (bottom left corner; probably not, is most likely a hoof of the following item.)

(2) Piglet from Winnie-The-Pooh or

(3) STRAIGHTENED-OUT SEA-HORSES.

EXPERTS ARE DEBATING WHICH FORCE THE ALIENS WORSHIPPED or were more similar to.

Debate will follow.

annotated images on mars

(I hope you realize that was all said with tongue firmly implanted in cheek?

(But some folks took the ‘Face on Mars’ thing seriously. That includes a DC-area astronomer who used to work for the US Naval Observatory by the name of  Tom Van Flandern. He wrote a book affirming that and many other stranger things.)

face on marsThe image above is the one that drove some people to make all the fuss. However, closer images from various orbiting cameras show the hill differently. Here is a page with lots of detail.

Piglet:

piglet

Why is the moon so high in the sky in winter?

And was it in fact directly overhead last night, near the beginning of the eclipse?

It sure looked like it was to me – though I didn’t take any measurements because I was only wearing my pajamas, my coat, and my slippers as I stood in the freezing cold on the snow-free but still-frozen concrete walk in front of our south-facing, Northeast DC  house.

[Yeah, I was being wimpy, only going out twice all night to look at the eclipse, but I was really tired, and I had to get up in the morning to give a full day’s guest lesson on astronomy to four, 70-minute middle school classes for a fellow teacher, so it was kind of  out of the question to stay up all night. (There is no way I could have followed through with the lessons if I had!)]

Maybe I’m just weird, but I have from time to time noticed, and marveled at, the fact that during the winter, the moon at times appears like it’s almost directly overhead. Let me emphasize that: to my unaided, subjective vision, without taking the trouble to measure it, during the winter, the moon sometimes appears to me to be directly overhead (at zenith).

However, everything I know about astronomy of the solar system tells me that this is probably impossible, simply because we do not live in the Tropics (with a capital T: the zone between the Tropic of Cancer and the Tropic of Capricorn). That’s the only part of our planet where the sun is ever directly overhead. (Don’t believe me? Use your internet resource skills and look it up. I’m not going to tell you just how to do that, because since you are reading this blog, you already know how.)

If you live in Washington,  the Sun will never appear directly over your house, no matter where you live in Washington, DC, and no matter how hot it may feel in the middle of summer.

And I figured that if the Sun and the Earth and the Moon were all aligned with each other, as in last night’s lunar eclipse, then the Moon would appear in our sky here in Washington as if it had simply traded places with the Sun for a while, and was at the same elevation. And that elevation just ain’t all that high.

Or so I thought.

Was I suffering from a version of the famous ‘moon effect’? (Which is a poorly-understood but almost-universal optical illusion about the apparent size of the moon,  a visual hallucination of sorts, caused by some internal human visual processing “bug” inside the various centers responsible for actually interpreting the photons and light waves that enter one’s eyes.)

Or is everybody else normal and it’s just me?

Or was the moon, in fact, at the zenith?

Or just very close to it, but within the theoretical and experimental range of error for this sort of thing?

I am going to try to settle this in two ways.

First of all, theoretically.

I used a rather widely-used piece of instructional geometry software called “Geometer’s Sketchpad” (version 5 in this case) and a couple of drawing and painting programs. I also used Google Earth to find out where on Earth are the places that are directly south of Washington and are on the Tropic of Cancer or on the Equator, as well as the spot on our planet that is diametrically opposite in position to Washington, DC.

I was rather surprised to find out where those places were. They weren’t really where I expected, and I of all people should have known better.

For example, I thought I remembered that Havana, Cuba, was just inside the Tropics, but Miami, Florida, was just north of the Cancerous Tropic. Or was that the Topic of Cancer? (Ha, ha, that was two intentional puns. If you don’t get them, or don’t think they are funny, that’s fine with me.) And I also remembered having been to some places in Florida that it was south of DC.  So I kinda figgered that the Tropic of Cancer would intersect our DC line of of longitude (about 77 degrees west) somewhere in the water between Havana and Miami.

Surprise: not very close. Just for fun, try guessing or figuring out the answer yourself. I’ll hide the answer at the end of this column, at (1).

And directly south of DC, on the equator? I always kinda figgered it would be somewhere in Brazil.

No surprise this time, I was wrong again. When I looked carefully, I discovered that 77 W and 0 degrees N or S is located… (2).

How about the point diametrically opposite to Washington, on the exact other side of the globe? Well, on this one I was fairly close. But calculating where this is, is a bit tricky. The latitude is OK. Any point at X degrees north is directly opposite some point that is X degrees south. So wherever it is, it’s at 39 degrees south. But the longitude is harder, because for most locations, Y degrees west is not opposite Y degrees east. What you have to do is change your latitude by exactly 180 degrees. Now here, you can either add or subtract. I would prefer to subtract, here. So 180 minus 77 gives us 103. (Of, if you prefer, 77 minus 180 gives -103.) And the way I interpret that 103, or -103, is to consider that as being 103 degrees east longitude.

Now knowing that DC’s literal antipode is roughly located at 39 degrees south and 103 degrees west, can you guess, or find, where that is? (3)

Here is the diagram that I made.

Bottom Line: if my diagram is correct, the full moon last night, at its greatest elevation or altitude last night, should have been about 15.5 degrees from the vertical (or 74.5 degrees from the horizontal). And that angular distance from the zenith should have been clearly and plainly obvious.

But it wasn’t. To me.

Now that’s just last night. Is it possible for the moon to be inclined a bit to the apparent orbit of the sun – that is – when the moon is not undergoing an eclipse? And can that cause the moon to be even higher in the sky than it was during last night’s eclipse?

Answer: YES. The moon ‘s orbit around the Earth is inclined by just about 5 degrees from the Sun’s apparent orbit. Thus, in different years and months, the details of which I will ignore right now ’cause it’s way too complicated for this here blog today, the moon might be as high as 10.5 from the vertical (79.5 degrees from the horizontal).

Next time: actual measurement

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Spoiler

answers below

or you could interpret my diagram..

(1) 77W and 23.5N turns out to be right next to Nassau, the capital of the Bahamas!

(2) it was about 100 or so miles east of Quito, Ecuador, along the banks of some huge jungle river that probably flows into the Amazon River, but doesn’t even seem to have a name. Nor any towns. Or roads.

(3) It’s located several hundred km, mi, or nm west-south-west of Perth, Australia, in the middle of the Indian Ocean. No land for hundreds of leagues in any direction, as the pirates or sailors or yarntellers of yore might say.

Total Lunar Eclipse Visible on the night of December 20-21

Lunar Eclipses are really amazing. The  one coming up on the date of the 2010 winter solstice starts rather late at night (around 1:30 AM on Tuesday the 21st of December if you live in the US eastern time zone), and takes about an hour to reach totality at roughly 2:41 AM. The moon will start leaving the earth’s shadow at about 3:53 AM.

The moon will actually enter the earth’s penumbra (partial shadow) about an hour or so earlier, but it’s hard to see.

Sometimes, the eclipsed moon is a bright coppery color. Other times it appears blue-ish, or brown. Other times it’s nearly totally invisible. Its exact appearance to the naked eye depends on how deeply it enters the earth’s total shadow, as well as on what’s going on in the earth’s atmosphere. Will our various levels of air bend enough light to illuminate the moon, or will our atmosphere be too full of dust and dirt to do so? You can only find out if you get up to watch it yourself.

A couple of web pages to peruse for further information:

http://science.nasa.gov/science-news/science-at-nasa/2010/17dec_solsticeeclipse/

and

http://shadowandsubstance.com/

and

http://eclipse.gsfc.nasa.gov/eclipse.html

Published in: on December 18, 2010 at 4:19 pm  Comments (1)  
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First Post

Hello, everybody,

This is my first attempt at putting up and maintaining a blog.

My main interests here will be education, public policy, math, astronomy, and science.

Recently retired from DC Public Schools, I have been doing some research on educational progress (or lack thereof) in that school system before and after the reign of our media-darling school Chancellor, Michelle Rhee. A lot of people have been throwing around a lot of rhetoric about how they are trying to put children first, but there has not been nearly enough in the way of actual facts. I have been trying to remedy this imbalance.

Some of my previous entries on this topic were sent as emails to various email list-serves made up of people interested in bettering the schools, but in a rather different way than Rhee. I will try to collect some of my previous posts and publish it here. One of those list-serves is http://groups.yahoo.com/group/concerned4DCPS/

I also posted on http://realeducationreformdc.blogspot.com/ which is a good resource as well.

Warning: since we have lots and lots of schools in DC, a good bit of my data will be in the form of huge spreadsheets comparing schools where Rhee replaced the previous administrations with the schools that did not experience such changes. The data take a while to wade through, and the arithmetic that I had to do was tedious in the extreme, but the results are quite informative. If you can compare, add, subtract, multiply and divide two decimals, and if you understand the meaning of percents and can read a graph, you should have no difficulty in understanding the results. (No algebra, geometry, or calculus is needed!)

I will have to learn how to post the spreadsheets and, in general, how to set up and maintain this blog.

I have another website that I put up about five years ago. Most of the things on it are still valid, but I imagine most of the links are probably broken. FWIW, here is the URL:

http://home.earthlink.net/~gfbranden/GFB_Home_Page.html

GFB

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