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Monday, March 31, 2008

Longer exposure times

Playing with longer exposures here. Captured the Pinwheel Galaxy again, almost twenty 1-minute exposures stacked.

Here is a capture of the Christmas Tree Cluster, portion of the dim nebula is visible. This needs some more attention in the future.

My very first digital astrophotograph, taken of the Great Cluster M13 in Hercules, did not do it justice. So, here is my second attempt. I think this is a little better. Could probably work on this, again.

Took a longer exposure shot of M81 and M82, also referred to as the M81 Group, with some technical data. Another view worthy of some better image taking.

Saturday, March 29, 2008

Busy night

Well, finally had a dark night. Moon didn't come up until 2:30 AM. My 8-year old daughter dearly wanted to join me. So, I walked her through how to use the telescope to take pictures, and she proceeded to tell me that she wanted to take a picture of the Rosette Nebula. Heh. She did great, managing to capture 20 frames ranging from 30 seconds to 1 minute in exposure. The results of her efforts are below, she was very excited.

Now, she's created a list of other heavenly objects she wants to go after. I won't be lacking for company.

Had a reasonable good night. Took some strictly technical shots of the Leo Triplet and Virgo galaxy cluster to evaluate. Will not be able to resolve anything beyond magnitude 13, but interesting to consider what else is lurking there.

Somehow, taking photos of a beautiful bright star is irresistible. So, I did. Arcturus appears below, dressed up with a legend of the constellation Bootes in which it resides as the alpha star.

Captured the open cluster M41, again not as striking as some, but certainly filled with stars!

I was surprised by the next one, the Beehive Cluster M44, this looked great!

In my wonderings, I settled back on Hercules and found M92 showing brightly in my telescope. I hadn't realized another significant cluster was in the same constellation as M13. Cool. Grabbed 10 frames of 1 minutes exposures for that one.

The next shot is of the Pinwheel Galaxy M101, this is kind of a test shoot for me. My recent attempts at galaxies has been pathetic. The results of this night proved to be better. Another 10 frames of 1 minutes exposures on a dark clear night reveals the subtle blue color and some of the brighter blue elements of this spiral galaxy. Will keep building stackable images of this and other galaxies to help improve the signal to noise ratio.

Took another 5 frames of 1 minute exposures of M104 before calling it quits last night. Stacked these on top of the prior ones (see early post below) and the final image shows improvement from before. Looking forward to another night to do the same with the frames I've captured for M101!

Wednesday, March 26, 2008

Follow up from prior night

Follow up from last night's attempts. The first is M37 an open cluster, not particularly outstanding but rich with stars. Next is the first attempt with eyepiece projection, using 1.25" eyepiece adapter, camera adapter, and 5mm ultrascopic to go 140x. Unfortunately, I realize now I should have moved to a nearby star for fine focus, rather than trying to do it with Saturn. Was difficult. Will throw in a 2x Barlow next time too for approximately 290x magnification. Should be interesting.

An easy galaxy to start with...

Here is the Sombrero Galaxy, captured with thirty fifteen second
frames at prime focus. It may be worth attempting eyepiece projection
to pull in a higher magnification. Will obviously not resolve like in
an 8" aperture scope, but at least I could leverage the 8 million
pixels in the camera.

Monday, March 24, 2008

Some more great first digital shoots

Above we have the Pleiades in the constellation Taurus. Again, like the previous shots, this was taken with a full moon. Some of the deep blue nebulosity shows through, some subtle color levels are buried here. My friend Carl used Photoshop and pulled out the following boost. A little noisy, but amazing to see the nebulae around these hot blue stars. Out of my little camera no less.

What astrophotography album would be complete without the Great Nebula in Orion, M42. Taken the same night with the Pleiades above, this image of M42 was a result of only thirty 15 second stacked frames.

I'm not using an autoguider, no real need with these short exposures. It also just seems wrong to automate everything, what's the enjoyment in that? Every shoot is manually focused, each exposure is timed manually, and each frame is processed individually, aligned, and adjusted with the help of Nebulosity by Stark-Labs. It took two hours to work the M42 image data to satisfaction, there is definitely a feeling of hands-on craftsmanship and accomplishment.

This is for my peace of mind and a desire to capture the things I see. Something I can pass on to my children.

Hey this is fun, another globular cluster

Here lies M5. I find this a more attractive scene than the lone M13.
The solitary bright star here lends to the depth of the image.

My first astrophotograph in 25 years

Captured finally on a night with successful alignment, clear skies, and perfect focus. Full moon didn't appear to degrade my ability to capture this shot.

The lovely Great Globular Cluster M13 in the constellation Hercules.

My setup includes a heavy duty Atlas EQ-G mount with a brand new Orion 6" fast f/5 Newtonian reflector OTA. After a few months of struggling to learn digital astrophotography with a DSLR, I finally achieved success!

My recipe:

- Reasonably accurate polar alignment (a little better than aiming it at the North Star, dude)

- Automatic dark frame (noise) subtraction, as provided for by the most excellent Canon Digital Rebel XT

- 1600 ASA (high gain, mo' power)...a lot of folks online tell others to use 400...this is somewhat misleading given the latest DSLR technology. If you can subtract out the noise levels, get as much gain as you can. You don't need to triple or quadruple your exposure times for fun!

- Short exposure sequences (40+ 15 to 30 second exposures)

- 2" wide focuser and 30% larger secondary mirror to fully illuminate 100% of the DSLRs CMOS detector (this is a big deal)

- Hartmann mask for rough focus and 11:1 fine focus control to dial it in (most important last step to taking the shots)

Have always been interested in astronomy, and now I can begin again with something started in my youth. Will begin my survey of the Messier objects...see how far I get. This is going to take a while...