Sunday, August 19, 2007

Out of focus Ring Nebula

I had the chance to do a little astronomy in the backyard tonight. It was very clear and the transparency was excellent. However, according to the clear sky clock, the seeing was only average (this is due to turbulence and temperature differences in the atmosphere). Bad 'seeing' can affect the view of detail on planets but should still allow one to observe deep sky objects. One of the downsides of silicon valley for astronomy is its relative low altitude (on average ~200 feet) which results in frequent poor seeing.

This is the first time I've set up the scope in several months. The new power supply worked like a champ, I highly recommend it. I was a little more careful in my polar alignment but its still not perfect. I've been reading about techniques like drift alignment for accurate polar alignment, but I have two problems; much of the hemisphere is blocked in my backyard, and I don't want to spend two hours polar aligning my scope for a night of viewing.

I did a combination of viewing and imaging. For viewing, I was limited to viewing close to zenith (due to neighbor houses and trees) saw the most visible deep sky objects; the Wild Duck Cluster, the Dumbell Nebula, the Ring Nebula, M56, M29 and M39. I also wanted to try some quick imaging with the Meade DSI. I used Vega to try and focus the scope. After 20 minutes of trying I gave up and went with 'close enough'. It is a frustrating experience trying to focus an older SCT for CCD imaging. The slop in the focuser not only shifts the image but also makes it difficult to get precise focus. I will be getting the Petersen EZ focus modification soon, so hopefully this won't be a problem when imaging this winter. Focus problems aside, I like the color I got, and visual observing was great tonight. I left the scope set up, so hopefully I can do some more viewing and imaging tomorrow night.

Technical Specs: Meade DSI on LX90 8" SCT /w f/6.3 focal reducer, Lumicon deep sky filter. ~12 15s exposures.
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