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Archive: Astronomy

April 28, 2008

Improving astronomical video using VirtualDub

YouTube user kwakhed23 pushed out this video showing before and after imagery of the Moon. In the "before" part of the video, you can see the effects of the atmosphere warping the Moon's image as it passes over the frame. In the "after" video, a temporal noise reduction filter is applied using the open source video tool VirtualDub. It's difficult to tell for sure in the YouTube compressed video, but it appears to have cleaned up the image nicely.

i thought this might be useful to other amateur astronomers who use the "mount the camera on a tripod and point it at the eyepiece" technique. you should be able to get much more detail this way.

I've used VirtualDub for deinterlacing and other random video cleanup projects before, and it's a very handy tool. I'm not certain exactly which filter is being used by kwakhed23, but in addition to the built-ins, you can check out Donald Graft's site for numerous other contributed filters which might be worth playing around with.

Better Astronomical Images Via Filtering
VirtualDub
Donald Graft's Collection of VirtualDub Filters

December 13, 2007

Astronomy Hacks author on WNYC's Leonard Lopate Show

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Robert Bruce Thompson, co-author of Astronomy Hacks and the recently released Illustrated Guide to Astronomical Wonders, appeared on WNYC's Leonard Lopate show last week:

Please Explain: How to Be an Amateur Astronomer

Anyone can learn to be an amateur astronomist - even here in New York City, where you often can't see any stars!

Richard Rosenberg, President of the Amateur Astronomers Association of New York, tells us about the best spots for stargazing in the city. Bob Thompson, author of The Illustrated Guide to Astronomical Wonders, explains the equipment, how to read star charts, and how to locate and identify objects in the night sky.

If you missed the segment, you can listen online! Link

November 6, 2007

Build your own telescope

When you have more than a passing interest in amateur astronomy, you quickly find that the hobby can get expensive fast, especially when you start dreaming about getting a bigger scope that will collect more light.

Maximizing the aperture to cost ratio is the Dobsonian telescope, a simple large-aperture reflector on an alt-azimuth mount, named after John Dobson, a former Hindu monk turned amateur astronomy evangelist. The Dobsonian and its numerous variations are designed to be easily built using inexpensive materials, and it has become one of the favorite tools of the sidewalk astronomer.

John Baichtal at Wired's geekdad blog posted a few resources for building your own Dobsonian today. Of these, Craig Jones' documentation of his own telescope design (pictured above) provides a really nice walkthrough of the telescope making process.

The critical element of any reflector telescope design is its mirrors. It still amazes me, but it's possible for a non-specialist to grind their own mirrors as well. While it takes a significant amount of time and patience, it doesn't take expensive tools or years of experience. In his mirror grinding howto, David Bourgeois writes:

At some point it becomes a fascination for many people to get a better instrument. Unless you have a large pocket book, the only practical way to make a large instrument is on your own. Depending on your resourcefulness and ingenuity, you may save yourself considerable money. The down-side of this is, however, a good bit of time and work. But if the idea of making something accurate to a few millionths of an inch with nothing more than two bits of glass, some common tools, and some jury-rigged testing apparatus appeals to you, then a bit of work won't stand in your way!

Because of the Dobsonian's popularity, there's really a wealth of information and resources available online for building one from the ground up. You'll still be putting money into the right eyepieces, but with a bit of research and time you can gaze at the heavens with a much larger scope than you can afford to buy. All with the satisfaction of having built a precision instrument in your own workshop.

References:
Build Your own Dobsonian Telescope - Link
Craig Jones' Dobsonian Documentation - Link
Grinding and Testing a Telescope Mirror - Link
Dobsonian Telescope @ wikipedia - Link

Astronomy Hacks @ the 21st Annual Cathedral Gorge star party

Make's own Katie Dougherty sent a few copies of Astronomy Hacks to the Las Vegas Astronomical Society, and she heard back from Geary Keilman, the President of the group. Sounds like the books made it into good hands!

Here are the names and some pictures of the winners of the Astronomy Hacks books you generously donated to our 21st Annual Cathedral Gorge Star Party.

Astronomy Hacks winner Alex Gonzales
Astronomy Hacks winner Douglas Barlow (he won two of the books)
Astronomy Hacks winner Ron Levandoski (sorry no picture)
Astronomy Hacks winner Rick Brashears (sorry no picture)
The ugly guy with the black shirt and shades is me.

Thank you for supporting our star party and publishing such a great astronomy book for beginners.

We're really glad to hear you all liked the book! - Astronomy Hacks (order now at the Maker store)

Related:

Illustrated Guide to Astronomical Wonders - Link
Las Vegas Astronomical Society - Link

October 9, 2007

Use your iPhone as a stargazing companion

NightLight wrote in with a request for a red overlay to "use your iphone in the dark but keep your night vision." I was reminded of the hacks about using red film in Astronomy Hacks: put it over your PDA or notebook computer, and you are all set. But to try it out, I needed to find an astronomy site that works well on the iPhone. Many online planetariums use Java to do their thing, but Your Sky is a great web site that does a couple of things simply and quite well: you can punch in your latitude and longitude, and you get a view of exactly what's above you at the moment. You can tap to zoom in, and you can pan around. Just what I needed. (To save a little time, figure out your latitude and longitude on your Mac, save a bookmark for your Your Sky page in Safari, and sync your bookmarks to your iPhone so you can get to the star chart quickly.)

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July 27, 2007

Open source astronomy: Stellarium and Celestia

Hackszine reader ozastro made a request for a southern hemisphere night sky guide. Instead of a specific southern sky guide, here are a couple of really nice open source astronomy packages that you can download. One will allow you to view the night sky from any point on Earth, and the other will let you change your perspective to any point in the universe.

Stellarium, is a planetarium package that will let you view the sky from any time or position on earth. Pictured above is the southern sky (with constellations outlines), as seen from Perth.

Celestia is a little like jumping in a virtual space ship which allows you view realistic models of the solar planets as well as travel throughout the universe. Curious what the universe looks like from Polaris? Want to to view Io up close and personal? Check it out. It's worth the download.

Both packages are available as binary downloads for OS X, Linux, and Windows.

Downloads:
Stellarium - Link
Celestia - Link

July 23, 2007

Learn to navigate by the night sky

Can you spot Ursa Major, Polaris, Cassiopeia, Betelgeuse, and Orion in the photo above? Know which way is North? If not, here's a quick 15 minute drill that will teach you how to recognize a few constellations and navigate at night (assuming you live in the northern hemisphere).

For you city folk, this could come in handy if:

you're trying to get to a late night party
you become disoriented
the battery dies in that Google Maps enabled iPhone we've been blabbering about for the last couple weeks

Identify constellations and navigate at night - Link

May 14, 2007

10 ways to improve your night vision

Sam Noyoun posted an Instructable with 10 ways to improve your night vision. Robert Bruce Thompson and Barbara Fritchman Thompson covered some of these techniques in Astronomy Hacks (including the pirate eye patch trick), but there are a few I hadn't heard of:

1. Protect your night vision

It takes approximately 30 minutes for the human eye to adapt to darkness. Protect your night vision: do not look directly at bright objects (for instance car headlights when driving).
...

10 ways to improve your natural night vision - Link

Robert Bruce Thompson, who has had a lot of experience looking at dim objects in dark places, says that only a red filter will work: green and blue won't do the trick. Robert also says that the elite forces and soviet special forces techniques don't work.

Related:

Astronomy Hacks - Link
Snopes on carrots and night vision - Link

April 4, 2007

WIKISKY: Google Maps-Like View of the Night Sky

WIKISKY lets you see what's up in the heavens above. You can locate many deep sky objects, get detailed information on them by simply hovering your mouse, and see high-quality Sloan Digital Sky Survey images for selected parts of the sky. Type in your current location, verify your timezone, and you can use WIKISKY to help plan your next observing session - [via] Link.

Related: