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Thursday, May 29, 2008

Messier 13, Great Cluster

OMG, I think I just advanced as a lifeform!

Unbelievable! I guess my premise was correct. Third time's the charm. This most excellent shot of the The Great Globular Cluster M13 in the constellation Hercules was taken on the night of May 26th 2008.

151 x 15 second frames at 1600 ASA, roughly 38 minutes of exposure time.

Look below, I included a before and after shot, just to pinch myself. Incredible. Guess I found the signal, Mr. Universe.

Messier 20, Trifid Nebula

First result from my little experiment. How'd I do? Charles Messier discovered this heavenly object in 1764. The red emission nebula comprises a young star cluster near its center, and is surrounded by a blue reflection nebula. 99 x 15 second frames, or about 25 minutes of exposure. Only tossed out 6 frames from 105, and I was being picky. Thats roughly 5%, a sixfold decrease in defects!

Compare this to the earlier post of M8 and you can see here that the starfield of the Milky Way around M20 lacks the background noise and reddish glow. Stars are more pinpoint. I did pick up some coma in the far upper right; not sure if there was some tube flexure or impact from additional temperature drop.

Wednesday, May 28, 2008

A little experiment...

I've decided to play with exposure settings. Over the last two months, I've extended unguided exposures from 15-30 seconds to 1 minute frames, and along the way observed how far the impact of tracking error goes. In any given run of 1 minute frames, I will throw out 30% due to noticeable tracking error occurring every 7-8 minutes. After spending 3 hours to take the photos, that seems like a waste of good photons.

"Well, duh!", is probably what some of the hardcore computerized brethren would say. Yes, I could get an autoguider cam, get out laptop, install software, add more cables, adjust guide scope to reasonably bright star, and consume more time in setup and prep.

Or...I could simply take shorter exposures and significantly increase the quantity. Its all about the signal. As Mr. Universe would say, "You can't stop the signal, Mal."
I believe taking a very large quantity of short, high-gain exposures will produce a more desirable signal to noise ratio in the end, reducing much of the 'blowout' in some of the brighter nebula and globular cluster shots, thereby producing richer results, without turning my scope into something from The Matrix. -- So Say I

The emphasis here is on digital astrophotography with the minimum amount of gadgets and expense. Once confidence and happiness is achieved at this level, you certainly can go up ($$$) from here as far as your wallet will take you! IMOP, the most expensive piece should be a quality, motorized German equatorial mount with computerized GoTo handheld. The GoTo saves a significant amount of time and is self-contained. A simple OTA for light gathering should not cost more than $500, and at that cost, driven by your desired aperture. A high-gain DSLR camera body can be found online or at your local fence for $400 or less, providing mirror lockup and automatic noise reduction (dark frame subtraction) built in.

* leveled mount and polar alignment via polar scope (a few minutes)
* 3-star GoTo system alignment (5 minutes)
* laser collimation (less than 30 seconds)
* DSLR focus with LCD review/zoom method (1 minute or less)
* unguided photography using shutter remote for as long as your camera has power and your CF has memory left (3.5 hours)
* beer, coffee, or both (your choice, no time limit)

Folly? I'll let the pictures stand on their own merit. You can all laugh at me later. The next round of astrophotography will be captured this way, without making any changes to post-processing method.

Skol and Compai!

Sunday, May 25, 2008

Messier 8, Lagoon Nebula

Couldn't wait any longer, Moon still rising during prime photography time, and the constellations Sagittarius and Scorpius are appearing earlier now in the southeastern sky. With the Moon glow, I decided to drop frame exposure to 30 seconds. This image comprises 94 frames, or roughly 47 minutes. Beautiful.

Saturday, May 3, 2008

Zeta Scorpii

In addition to Mu Scorpii, the Scorpion's Tail is comprised of an open cluster NGC 6231 (partially viewed above) and the binary Zeta Scorpii (near the bottom of the photo). This image was simply 2 one-minute frames slapped together. Another part of the Scorpion's Tail includes a diffuse nebula referred to as the Northern Jewel Box. Will save that for another night.

Mu Scorpii

Before heading off to bed, I spotted what appeared to be a comet-like image in the lower southwestern portion of the sky; the southern end of the constellation Scorpius. Having lived in the Northwest and at sea-level for most of my life, I've never had the opportunity to view this portion of the sky. Looking through the telescope it became evident that this image was comprised of an open cluster, and some binary stars.

The photo above is comprised of 5 one-minute frames for Mu1 and Mu2 Scorpii, an eclipsing binary. Mu1 is considered a variable star due to the impact of the eclipsing behavior on its apparent magnitude. May be a little over-exposed.

Messier 83

I have made a list of the most interesting Messier objects left to look at, either due to apparent size or magnitude. M106 and M83 were the goals of this fine dark night. After capturing M106, I had sufficient battery power left to get 25 one-minute frames of M83.

Messier 106

Did not realize there were other galaxies in view until after the photo was processed. 42 one-minute frames, 1600 ASA. Not as many frames as I had planned, as the equatorial mount was extended in that direction as far as it would go. To keep going would require slewing completely around, then the mirror would have to be collimated again, and the camera focused and adjusted to recreate the same orientation as seen in the picture above.

I decided to move on to another object.