Covering information that shouldn't be caught out in the open.
Covering information that shouldn't be caught out in the open.
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September 20, 2006 The Ring Nebula M57, NGC 6720, is one of the brightest planetary nebulae in the sky, and at this time of year passes nearly overhead for midnorthern viewers. This is usually one of the first deep-sky objects most beginners find, as it has some easily remembered “pointer” stars nearby. The first view, even through a tiny telescope, is stunning: it hangs there, like a smoke ring. This was taken through my 12” Meade LX200 GPS working at its native (nominally f/10) focal length, and is a composite of 29 images, 30 seconds each, tracked but not actively guided. The “drizzle fraction” was set to 50 percent. Post-processing in Photoshop. I'm getting better at this, I think. Compare to an image from last year, found by clicking on “Astrophotos” in the left-box menu.
To give some idea of how far we've come in 30 years, back in the summer of 1974 or 1975, I used the 16” Boller & Chivens Cassegrain telescope at Northwestern University's Lindheimer Observatory to make my first long-exposure images. I remember squinting at a dim star through an offset guider for about an hour, while listening to WFMT on a portable radio. The images were taken on glass plates, what looked like 1x3 microscope slides that Kodak had treated with special "astronomical emulsions" that are long off the market now. After taking the images of M13, M57, and I think M27, I took the elevator down to the darkroom and processed them just before dawn. That was the only all-nighter I ever pulled in college. An hour to get an image. And now we get a recognizable image in 10 seconds and build up a stunning image, without the grain of those old glass plate emulsions, in about half an hour. With a “consumer grade” telescope. While doing other stuff on the computer. I see I captured not only the one elusive central star (to see it visually is a test of sky transparency, telescope, and eyeball skills), but three others as well. These are not artifacts; see the Hubble image, here. (Man, they get tight stars with that thing...)
Another Blue Snowball Another bright planetary nebula is C22, the “Blue Snowball,&rdquo which I imaged a few days earlier through an f/3.3 focal reducer. (See Sept. 17 entry). Well, that turned out to be so tiny and bright that I figured I'd give it a try with the scope in straight - through (nominally f/10) mode, just like the Ring Nebula, above. This is a composite of 150 exposures of 10 seconds each. No attempt made here to try to get a nice composite showing dimmer field stars. Scale is exactly the same as M57, above.
The Pillars of Creation On Sept. 18, I shot the open cluster and associated nebulosity Messier 16 (M16), or NGC 6611, popularly known as the Eagle Nebula. This was made famous by the Hubble Space Telescope photo called "The Pillars of Creation." This is an area where new stars are being born. Here's a good explanation. This is a combination of 30 exposures at 15 seconds, "drizzle fraction" 0.50, "drizzle resolution" 2.00. Nominally f/3.3 focal reducer. Again, this image looks a lot better, and brighter, in Photoshop than here on the web and I don't know why.
Sure, the famous Hubble image is a lot more detailed, but mine's a lot cheaper and I can get my scope repaired about 10 miles from here.
It took me several tries to get a good image. I sit inside at the computer, working the telescope remotely via a serial connection to move and focus, and a USB connection to the imager. At about 8:30 on the 19th, this flashed onto the screen:
I noted the time and started digging. I didn't think it was an aircraft, because they normally don't pass in that part of the sky. It was about 8:30 PM, local. A quick look at the Heavens Above site yielded this table of bright satellite passes for my location. I've highlighted in yellow the most likely suspect.
Let's see, can I confirm that? I powered up the free skymapping program Cartes du Ciel and had it plot all the satellites for that narrow time window, using the USAF Space Command three-line elements set that I downloaded a few weeks ago (normally, I should use more recent data than that, but this time at least, old data was good enough). Within 8 minutes of the pass, I had the culprit identified and confirmed. Here's the portion of the Cartes du Ciel table with satellite passes, and the track going right across M16 / NGC 6611 at the time in question.
So what is this thing, anyway? It's a Delta rocket booster left over from launching SEDSat 1 in 1998. So what is SEDSat 1? It was built by students at the University of Alabama/Huntsville. SEDS is Students for the Exploration and Development of Space.
September 19, 2006 Crepuscular rays While testing cars at California Speedway, in beautiful Fontana, CA, at oh-dark-thirty this morning, I saw this phenomenon just before sunrise – crepuscular rays. The lumps on the horizon are the Big Bear area: Mount San Gorgonio, Sugarloaf Mountain, San Bernardino Mountain, whatever, there's a whole bunch out that way. The second image was taken just as the sun peeked over the mountains. The dark streaks are the shadows of the mountains.
September 17, 2006 Blazin' blue snowballs, and photons on yer windshield More astro images from last night. Here's an object known as Caldwell 22, or NGC 7662, also called the Blue Snowball, a very bright planetary nebula.
This is a composite image; with the nebula itself processed for best visibility, there would be almost no stars visible. With the star background brought out, the nebula would be way overexposed. I suppose I could have done some sort of radial filtering, but since the area right around the nebula is black, this is a quick cut-and-paste job using layers in Photoshop, which keeps them nicely aligned (and since the raw data is the same for both images, there's no problem with getting perfect registration). This exposure consisted of 54 ten-second exposures over 764 seconds, with the "pixel fraction" in Drizzle set to 50%. F/3.3 focal reducer. Of course, Hubble gets a lot more detail. I also took another shot at Caldwell 30, NGC 7331. Oddly, there's more detail visible in the Photoshop view than in any other applications – even when viewing the exact same JPG file. (So it's not a question of 16 bit vs. 8 bit color). This image doesn't show as much of the spiral ams as the Photoshop view.
This is a spiral galaxy 49 million light-years away. So the light represented by this image left there a mere 15 million years after the dinosaurs checked out. Just think of it – all those photons, flying through space for all those millions of years, through dust clouds, through magnetic fields, through our atmosphere, through the front glass of the telescope, bouncing off the mirrors, only to crash into a CCD sensor and... die. There are three other NGC objects in the frame: NGC 7336 at top, 7335 at left above center, 7337 near bottom left, right next to a star. Here's a chart of the area. 59 images, 20 sec. exposure, f/3.3 focal reducer.
September 15, 2006 More astrophotos Fooled with the Meade DSI's "drizzle" function some more.
The individual LRGB channels are from a stack of 40 5-second exposures. This used the "drizzle" function to drive the telescope and make a larger image than the "native" size on the CCD chip.
It does look like the "coma" (stars blurred radially outward from center) is better now, although not completely gone. (Compare to Sept. 10). I removed a 15mm spacer from the stack, so it's only the Meade f/3.3 focal reducer, a Lumicon UV/IR block filter (which takes up about 15mm by itself), and then the Meade DSI camera. This resulted in a higher (slower) f/ratio, so I had to use the "drizzle" method to enlarge the imaging area. Stacked 10-second exposures.
The DSI software has an interesting function in which the software is able to generate a bigger image (imaging a larger area of the sky) by moving the telescope between exposures to build up a larger frame. This can have its drawbacks; I let it do its thing for more than an hour on the Cocoon Nebula, Caldwell 19 (IC 5146) with mixed results. The scope did track around the corners of its imaging box, but shooting from suburbia, with possibly variable sky conditions and lighting, some artifacts were visible.
This image was built up by stacking 112 30-second images, about as long as I dare go without active guiding. It took well over an hour to collect enough acceptable images.
Why is this called a "drizzle" function? Interesting name. It was invented by some folks for use with the Hubble Space Telescope. The idea is that it "drizzles" little spots of light , or color, onto a "canvas" and thereby permits sub-pixel imaging. See for example this Wikipedia entry, under "Observations." Here's a meatier treatise from the Space Telescope Science Institute, the folks who operate Hubble.
September 10, 2006 Fooling with the telescope Last night, I shot this image of Messier 27, the Dumbbell Nebula, with my 12" Meade LX200 GPS telescope and a Meade DSI Color imager. This is a stack of 27 images, each an exposure of 10 seconds, selected automatically by the Meade DSI software (it saves, but does not combine, images which it detects as substandard; I might be able to improve on this with manual selection). This used a "drizzle" factor of 0.75, which is a way of getting resolution better than one pixel. The software moves the scope slightly between exposures so that over time, a given part of the image falls on different photosites on the detector.
I might be able to bring out the reds a bit more with processing, eliminate the saturation on the star at right center. But I see there's quite a bit of coma away from the center, and that's an optics problem. I might fool with different focal reducer to imager spacing, or if that's not the cause, just buy a better focal reducer. (Later) I tried a new astronomical image processing program, AIP4WIN Ver. 2 which came with the book Handbook of Astronomical Image Processing by Berry and Burnell. It does some pretty slick things. My first attempt at fiddling with the images using LRGB (Luminance - Red - Green - Blue) images (the Meade DSI generates an L image as well as the three colors) resulted in this:
Is this any better than the purely RGB image at top, generated by Adoble Illustrator? Don't know. After a point, these things become a matter of taste.
August 28, 2006 The Age of Advertising One of the underlying themes of modern life is advertising. Advertising is God. Everything is subservient to advertising. The primary function of your mailbox is to serve as a receptacle for advertising. Your "letter carrier" carries very few letters; instead, the Post Office is a quasi-government junkmail distribution service. Your telephone is not really yours, nor is your personal time; when the phone rings, you are expected to drop what you are doing and listen to an advertising pitch. And then there's the spam phenomenon. Almost nobody clicks on those things – almost. But enough morons click and buy, so it pays off for the spammer. Western civilization runs on advertising. Your firm might manufacture the worst piece of dreck ever invented by man, but if you hire a Madison Avenue ad firm, you will sell that product to millions of mindless morons, and be rich beyond your wildest dreams. Advertising is all-pervasive. Advertising is untempered by any trace of common sense or decency. Take for example this weekend's fatal crash of a commuter jet in Kentucky. And take a look at some of the images carried by monstersandcritics.com, along with "appropriate" Google ads (automatically generated by Google).
Gee, sorry to hear about your fatal crash, but I've gotta run, gotta download that "Fear of Flying" ringtone! The same sequence had other rotating ads. Including these gems.
And best of all,
I had to look up that "West Valley Flying Club." What a bunch of dorks. First we have an image that suggests the best reason for learning to fly is to avoid the social stigma of not being allowed past the "tenants and users only" gate.
But then we have this gem, for those who can already fly but are tired of that straight-and-level nonsense:
Look closely. "Go Acro" indeed. The plane isn't inverted; only the image. ("Photoshop Aerobatics," anyone?) And that's a runway up ahead. Taken as intended, it's supposed to show a plane inverted – on final approach. Yeah, that'll impress the guys in the tower. And the FAA. I could probably sell some "Custom Aerobatic Inverting Aviator Sunglasses." Consist of some frames with prisms epoxied in place. Save yourself the cost of aerobatic instruction! Avoid stressing your airplane, and your bank account! I could sell those suckers. I only need a good ad campaign. (Eh? What? Already invented? No problem. It's all in the advertising campaign...) That said, I'm killing the Google Ads on this page, and once I get around to it, other pages as well. They were usually for stuff like biodiesel and besides, nobody was clicking on them anyway.
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