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Thursday, September 25, 2008

Messier 39

This open star cluster is approximately 800 light years away and estimated to be from 200 to 300 million years old.

Unguided, 200 x 15 second JPEG frames, 1600 ASA, with noise reduction enabled.

Galaxy and Cluster, NGC 6946 and NGC 6939

An interesting view, here a nearby spiral galaxy, NGC 6946, highly obscured by interstellar matter of our own galaxy is contrasted in this photograph by a distant open cluster, NGC 6939, in the same field of view.

Since 1917, eight supernovae have been observed in NGC 6946.

Unguided, 204 x 15 second JPEG frames, 1600 ASA, with noise reduction enabled.

NGC 7293, Helix Nebula

Tried a difficult target, the Helix Nebula, a large planetary nebula. Given that it is one of the closest of such nebula to our solar system, you would think it was much more distant. Apparent brightness is spread across a vast surface relegating any other observing details deeper in the IR range. Clearly, photographing this kind of deep sky object approaches the limits of what can be reasonably done in an evening with the latest DSLR camera.

It is possible another alternative might work, taking successive exposures over several evenings. I have yet to try this. Maybe if I have time during Christmas break. Would really need to leave the telescope outside and in place for a whole week.

Unguided, 250 x 15 second JPEG frames, 1600 ASA, with noise reduction enabled.

Saturday, September 6, 2008

Messier 27, Dumbbell Nebula

Yes, Dumbbell here was the first planetary nebula to be discovered, and resides in the faint northern constellation of Vulpecula. The central star is a white dwarf, larger than any known white dwarf. In 1970, astrophysicists found the nebula around the star was expanding at 31 km per second, suggesting an age of only 9,800 years!

Unguided, 202 x 15 second JPEG frames, roughly 51 minutes of exposure, 1600 ASA, noise reduction enabled. Just stacked and stretched, great natural color and contrast. The images were taken between the hours of 10:30pm and 1:00am in the morning. The prior blog entry regarding M33 was taken afterwards until about 3:30am in the morning. The M33 shot is much more grainy, given largely to being in the portion of the sky over the Tucson light dome. In the future, I should probably avoid imaging toward the West and Southwest portions of the night sky.

Messier 33, Triangulum Galaxy

Unguided, 203 x 15 second JPEG frames, roughly 51 minutes of exposure, 1600 ASA, with noise reduction enabled.

This was a fairly dim object, even though it is listed at about magnitude 7. Could stand to get twice as many exposures to bring out more detail. Still, a really spectacular face-on spiral galaxy. It has also been referred to as the Pinwheel Galaxy, even though Messier 101 is officially recorded with that name.

Friday, September 5, 2008

Messier 45, Pleiades

At last, another chance to try the Pleiades now that I have had much more practice. This image is comprised of 288 x 15 second JPEG frames, unguided, 1600 ASA, approximately 72 minutes of exposure! A personal record.

This cluster is number 45 on Charles Messier's list of nebulous objects. This beautiful cluster of stars was also mentioned by Homer around 750 B.C.. It has had many names, including Seven Sisters, Matariki (New Zealand), and Subaru (Japan). Comprised of hot blue stars formed over the last 100 million years, the brightest stars illuminate ancient dust collected from the original formation of stars giving it the bluish nebulosity.

IC 5146, Cocoon Nebula

Well, here's a tough one. Unguided, 180 x 15 second frames, 1600 ASA.

The Cocoon Nebula is an emission, reflection, and absorption nebula all woven together in a young developing star cluster. Formed only 100,000 years ago and is 4,000 ly from Earth, fairly close in astronomical terms. What makes this interesting is the dark nebula you can see (sort of) trailing off to the left of the picture.

Wednesday, September 3, 2008

The LCD "zoom/review" focus method

A simple way to focus your DSLR for astrophotography without a lot of other expense like a costly knife-edge device or laptop with cabling and focus control software, involves zooming in and reviewing diffraction lines from a bright star near the deep sky target. This method works best with a Newtonian telescope, where the secondary mirror is suspended by 3 or 4 straight flat bars 90 degrees apart within the optical tube assembly.

With diffraction lines, the zoom-review focus method can be accomplished very quickly. Three focus frames taken during the prior night's efforts are shown here.

The metal bars commonly referred to as "spider" vanes, cause the attractive (or distracting) star-like diffraction lines observed in my photos. I find it a pleasing photographic effect. For non-Newtonian scopes, one could fabricate some vanes to attach in front of a tube assembly to create diffraction lines just during focusing. I've seen some photos on other web sites where amateurs have used Photoshop to add the diffraction lines artificially (honestly, it looks as fake as it sounds).

You always want to try and focus on something nearby, as slewing the telescope clear across the sky can disrupt the mirror collimation on your touchy Newtonian.

Tuesday, September 2, 2008

NGC 869 and 884, the Double Cluster

Another break in the storms, maybe this is the end of it. Under a beautifully clear and dark night, I was able to capture the Double Cluster below. Unguided, 257 x 15 second JPEG frames (roughly 64 minutes of exposure), 1600 ASA.

I attempted to get a parting shot of M6 too as it moves closer to the horizon, but the glow off my wall from my neighbors flood lights really ruined it. Even with 186 frames captured, it was like trying to take a picture with the moon out. Argh.