clear sky chart

Job 9:9

Job 9:9-10
9 He is the Maker of the Bear and Orion,
the Pleiades and the constellations of the south.
10 He performs wonders that cannot be fathomed,
miracles that cannot be counted.

Sunday, May 20, 2012

OTAA Scenic Vista Stargaze

This was my first star party and this was also my darkest sky location which I have imaged from.  Unfortunately there were some thin high clouds that turned into haze as the night progressed.  We had the best sky just after sundown until around 11pm.

It was well attended, quite a few guests came by to look through the eyepieces of various telescopes.  I did a short demonstration to some curious onlookers just before total darkness of Saturn, went through the entire process from acquiring to processing.

There were telescopes there of all sizes.  The largest was what I believe to be a 25" f/5 motorized dob.

There were probably 20 - 25 scopes set up of all different sizes, from about 4 inches to the 25 inch pictured above.

Unfortunately I didnt take any pictures until late, and most didnt come out very well.  There were a lot of scopes behind me when I took this picture, but they didnt come out well enough to post.

Once darkness fell, I started imaging, and I chose M51 for my first target.  I wanted to image familiar things to compare with what I had taken at home to see what the difference having a dark sky made.  The following image of M51 was the best image of the evening as the sky steadily worsened as the evening progressed.  I am rather happy with this image, but there was a nasty diffraction spike which kept it from being absolutely perfect coming from the star Alkaid (Eta Ursa Majoris) which was just outside of the field of view.  This image consists of a composite of 20 120 second frames at iso 1600 stacked.  The telescope was my 6" f/5, 40 minutes total exposure.

This one came out so well (except for the diffraction spike), that it is the only one which I uploaded as a png to preserve the sharp appearance.  Sky transparency, when this was taken was about 6/10, and progressively got worse after this was shot.

While this was imaging, I walked around the grounds and had a look at M81 thru the big dobsonian that was set up.  Climbing up on the 8' stepladder to look through the eyepiece gave me a real nice view of the galaxy.  It was quite bright.

When I got back to my scope, the imaging sequence was finishing up with M51.  I then slewed over to M57, the Ring Nebula in Lyra.  I was shooting through substantial haze, but it seemed to come out OK.  I was not able to capture the dimmer red halo around the object, due to the haze.  Knowing that this was not going to be as good, I only shot 9 - 1 minute frames at iso 1600.

There is somewhat of a red halo present, but its not as pronounced as in my earlier photo.

My next attempt was the Owl Nebula, M97 and M108, which share the same frame.  By this time, the haze was getting worse, and I believe I could have done better under clearer skies, as the Owl is somewhat dim to begin with.  There was some gradient and sky noise showing up in the background which I tried to remove as best I could.

The final image of the evening was M101.  I got about 10 frames before a car's headlights shining on the scope degraded the remainder of the frames.  I probably should have imaged this object first, but I was hoping the sky would improve, as it often does, as the evening progressed.  Unfortunately that didnt happen, so my M101 was not the greatest.

Not bad, but I'm sure it could have been better.

All of the images taken were unguided, and the maximum exposure per sub was 120 seconds.  The scope tracked very well with very little star streaking.  The worst case, and visible in the images were slightly egg-shaped stars.

Overall, I would say I had a successful evening, and with the quality of the images, I look forward to imaging from more dark sky sites.


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