brainwagon

Today I was cleaning out my office. I’m a clutterbug: I have tons of treasures, but also, let’s face it, an even larger amount of crap. When I first moved to California 19 years ago, everything I owned fit in 13 banker’s boxes. Now, I don’t even think my power adapters would fit in 19 bankers boxes. So, I was ruthlessly going through boxes and tossing stuff out. Along with endless old cds, and papers that I printed out, I found a bunch of stuff from one of my previous obsessions: telescope making. I even found a 6″ mirror, aluminized, carefully wrapped in optical tissue. I’ve pretty much abandoned telescopes in recent years, but I really should get back into it again.

Anyway, tonight I was strolling down memory lane, and encountered a link to something I hadn’t seen before: the Bahtinov Mask. It’s a gadget that you can place in front of a telescope to help you focus precisely. It uses a very clever arrangement of masks to produce a diffraction pattern which can be adjusted to a precise focus.

If you dig around, you can find all sorts of testimonials about how terrific they are. I’ll have to make one of these and give it a try. Perhaps if I can find someone who will loan me a laser cutter, I’ll even cut a really precise one.

Addendum: Here’s a link to a nice mask generating program that will output an SVG file for any scope you need.

Poking around on archive.org, I found that Louis Bell’s classic work The Telescope was available for download. It is a pretty nice book, well worth reading if one has an interest in astronomy and telescopes. It is part history, part engineering, and part user’s guide. It also includes some great illustrations such as the one below of Newton’s first reflecting telescope. Enjoy!

Internet Archive: Free Download: The telescope.

IMG0012
21st November, 2009

Dan Lyke of flutterby drew my attention to the astrometry pool on Flickr. If you upload an astrophotograph to this group, a process comes by later and tries to identify the stars in your image, and adds annotations and labels to it. Very nifty. Check it out. Try clicking the image above, and it will send you to the Flickr page with the annotations.

We were fogged in here, so I didn’t have an opportunity to watch, but it looks like I didn’t miss much: early reports are that basically no one saw any visible plume, not even at Mt. Palomar. Here’s a link to Sky & Telescope’s story:

SkyandTelescope.com – News from Sky & Telescope – LCROSS Impact: It’s a Hit — But Was Anything Seen?.

This Friday the NASA LCROSS probe will deliberately impact in a dark crater on the moon, with the ultimate goal of trying to decide if any water exists on the moon in these deep craters. As it happens, I was going to take Friday off from work anyway, so being awake at 4:35AM Pacific Time isn’t beyond the realm of possibility. I’m currently surveying my existing telescope equipment (most of which hasn’t been out for quite some time) and hope to be able to video the resulting impact. Regardless, I’m planning on being awake to see it. Check out the NASA website:

NASA – LCROSS

On this day in history, 400 years ago Galileo Galilei demonstrated his telescope to a group of Venetian lawmakers. In March of the following year, he would publish his most famous work, Siderius Nuncius (commonly rendered in English as The Starry Messenger). This invention ushered in the modern era of astronomy, and quite literally changed our view of the universe and humanity’s place in it.

While Galileo’s telescope would be considered relatively crude by modern standards, it had an influence for hundreds of years. On the right I have a pair of field glasses that are actually a pair of Galileian telescopes paired together, dating back to roughly the start of the 20th century (I think). As binoculars, they basically suck (very narrow field of view) but they are a cool relic to have on your desk.

I was scanning through the recent additions to Project Gutenberg, and found that Volume I of the Philosophical Transactions of the Royal Society, dating back to 1666 had been converted and uploaded. It’s got a lot of interesting stuff in it (as well as some uninteresting) but the thing which caught my eye was this description of some observations of Jupiter done by Hook using a sixty foot(!) telescope. In 1666, the achromatic telescope had not been invented, and telescopes had very small aperature and very long focal lengths to avoid chromatic aberration. Yet using these telescope, Hook wrote very clearly about shadow transits crossing the surface of Jupiter. Worth checking out.

Philosophical Transactions Vol. I.

Some Observations lately made at London concerning the Planet Jupiter.

These, as they were made, so they were imparted, by Mr. Hook, as follows:
Sch. III.

A. 1666, June 26. between 3. and 4. of the Clock in the morning, I observed the Body of Jupiter through a 60 foot-glass, and found the apparent Diameter of it through the Tube, to be somewhat more than 2. degrees, that is, about four {246}times as big, as the Diameter of the Moon appears to the naked Eye. I saw the Limb pretty round, and very well defin’d without radiation. The parts of the Phasis of it had various degrees of Light. About a and f, the North and South poles of it (in the Fig Q.) ’twas somewhat darker, and by degrees it grew brighter towards b. and e, two Belts or Zones; the one of which (b) was a small dark Belt crossing the Body Southward; Adjoyning to which was a smal Line of a somewhat lighter part; and below that again, Southwards, was the great black Belt c. Between that, and e, the other smaller black Belt, was a pretty large and bright Zone; but the middle d, was somewhat darker than the edges. I perceiv’d about 3h. 15m. near the middle of this, a very dark round Spot, like that represented at g, which was not to be perceiv’d about half an hour before: And I observed it, in about 10. minutes time to be gotten almost to d, keeping equal distance from the Satelles h, which moved also Westwardly, and was joyn’d to the Disk at i, at 3h. 25m. After which, the Air growing very hazy, and (as appeared by the Baroscope) very light also (in weight) I could not observe it: So that it was sufficiently evident, that this black Spot was nothing else, save the shadow of the Satelles h, Eclipsing a part of the Face of Jupiter. About two hours before, I had observed a large darker spot in the bigger Belt about k, which in about an hour or little more (for I did not exactly observe the time, nor draw the Figure of it) moving Westwards, disappear’d. About a week before, I discover’d also, together with a Spot in the Belt c, another Spot in the Belt e, which kept the same way and velocity with that of the Belt c. The other three Satellites in the time of this Eclipse, made by the Satelles, were Westwards of the Body of Jupiter; appearing as bright through the Tube, as the Body of Jupiter did to the naked Eye, and I was able to see them longer through the Tube, after the day-light came on, than I was able to see the Body of Jupiter with my naked eye.

Glancing through the recent additions to Project Gutenberg, I encountered this nice little book which details some of the pioneering scientists in the field of astronomy. It even has some nice illustrations which might be useful, such as the one on the right of Newton’s first reflecting telescope.

The Project Gutenberg eBook of Pioneers Of Science, by Oliver Lodge.

While recovering from my brief outpatient procedure yesterday, I was surfing around, looking for the ChirpHell and ChirpPix programs that some people mentioned in the context of creating the Hellschreiber IDs that I saw yesterday. A bit of Googling revealed that they were written by DF6NM, so I did some more websearching, and as soon as I found this page:

NavSpaSur Lunar Imaging by DF6NM

I forgot entirely about ChirpPix. This page is all about using the reflections from the NavSpaSpur radar fence to generate actual pictures of the moon. Very, very neat. I should think about this, it seems like a very nifty project.

He also seems to have done some interesting work in the LF spectrum.

While reading up on Adrien’s blog, he mentioned a site which I hadn’t seen before. It attempts to predict how good the conditions will be for astrononomy and astrophotography for locations around North America. For instance, I teach (well, more properly used to teach, since I’ve been enormously busy lately) telescope making at the Chabot Space and Science Center. Here’s the prediction for them:

As you can see, it’s not a particularly dark site, but the information is quite useful. Thanks for blogging about this Adrien!

It’s been quite some time since I’ve bought a book about telescope making: I just have been more absorbed in the world of amateur radio lately. Still, on my trip to Portland, I noticed that James Daley had published a book on an unusual telescope: the Schupmann.

The Schupmann Telescope

The Schupmann is an unusual telescope in that it is a refracting telescope with nearly perfect correction for chromatic aberration without using any exotic glasses. The main objective lens is a simple single element lens, which has a considerable amount of chromatic aberration. To cancel out this aberration, the light path is passed through a Mangin mirror: a meniscus lens where the back surface is coated with a reflecting coating which turns it into a second surface mirror. By carefully balancing the power of each of these elements, you can cancel out the chromatic aberration of the main lens. It’s a remarkable design, and rather uncommon. The only one I had seen was Jerry Logan’s superb 7″ instrument at the Riverside Telescope Maker’s conference.

Here are some links to the associated patent:

LUDWIG SCHUPMANN – Google Patents.

LUDWIG SCHUPMANN LUDWIG SCHUPMANN

It’s been quite some time since I posted a “Gutenberg Gem”, a book from Project Gutenberg that might deserve some special attention. Today’s example contains a bunch of nice illustrations about telescopes and their associated astronomical instruments. Very nice. Not just traditional refracting telescopes, but also instruments like spectrum comparators and filar micrometers.

The Project Gutenberg eBook of Astronomical Instruments and Accessories, by Wm. Gaertner & Co..

Well, today is the the vernal equinox, known more informally as the first day of spring.  It’s a blustery, rainy day here, and it probably would have gone unnoticed by me except for the mention on Phil Plait’s Bad Astronomy Blog.  The equinoxes are a busy time for Phil, who debunked the idea that on the equinoxes, you can balance an egg on end: it turns out, you can do it any day of the year if you have a little patience and practice. Phil’s egg balancing was what originally drew my attention to his blog,  so I wish him and all my readers a happy spring.

[tags]Spring,Vernal Equinox,Bad Astronomy,Science[/tags]

Need some fresh wallpaper for your computer Desktop? Try checking out NASA’s top 10 Pictures, including the rather nice pictures of an active lava flow on Io pictured to the right. Cool stuff.

[tags]NASA,Space[/tags]

Reader Bill Harris reminded me that tonight is the night that Stardust, NASA’s comet sample return mission, will return to earth carrying its cargo of aerogel that was exposed to the particles in the wake of Comet P/Wild 2. At 2:12AM PST on Sunday morning, the probe will jettison it’s cargo at 105,000 feet over Utah, and helicopters will recover the cargo. Interestingly enough, they anticipate that only 45 hits will be recorded in the square foot or so of aerogel, so they have a project similar to Seti@Home planned to scan the plates, but instead of needing your computer time, they need your eyes. The entire panel must be examined under high magnification, and they want to employ volunteer labor to help find these particle hits.

In any case, check out the link, consider volunteering, and stay tuned for more info as it becomes available.

Stardust – NASA’s Comet Sample Return Mission

Addendum: Phil Plait has a nicer writeup and reminds that if the weather is clear, you might be able to observe the reentry of the probe from the Western U.S. It’s cloudy and rainy here, so I doubt we’ll get any chances here. Too bad.

Addendum²: Surprisingly, it looks like it might be clearing up. I’m thinking of trying to snap some quickie video of the reentry. It will be pretty low on the horizon when it shows up here, and I’m not sure exactly the best way to photograph this thing, but we shall see.

Addendum³: Nope, while the sky was clear, I suspect that the local horizon to the north was slightly too high, and the object passed behind it. Oh well.

[tags]Comet,NASA,Stardust,Space,Science[/tags]