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On Saturday June 19th Paul Lefevre and I meet at Sonoma Lake State Park? We found our way to the third parking lot, at about 1200 feet elevation, and set up our euipment and waited for nightfall. The drive to the site is very easy from San Francisco and from the East Bay as well, if one were to take the San Rafael Bridge, but any one coming from for South Bay via 101 or 280 will have the added hassle of driving through San Francisco to get to the Golden Gate Bridge.
The site turned out to be 85 miles from my house the distance was covered in about 1 ½ hours as opposed to 110 miles and 2 hours to the Peak
The parking lot is huge and Paul and I were the only ones there all night, except for one guy who had a GPS unit and was disappointed that we did not need to know our exact coordinates to do our observing. This lot would easily hold 150 scopes and the vehicles that carried them. However the lot is not paved. My guess is that it is of a dirt, clay and gravel mixture compacted very well. There were strong winds blowing in the afternoon but no dust at all was kicked up into the air because of it, however fast moving vehicles will raise some dust and if the wind is blowing, can be a cause of concern to exposed equipment. No fees are required and I guess we could have stayed the night in that lot if we had chose to do so.
At Sunset the wind had not died down, so we moved our equipment close to a knoll that blocked much of our view to the North but also blocked the wind very well. As soon as we got comfortable and settled in the wind stopped and it remained calm most of the time we were there, although it picked up again at about 1:30am.
The horizons at this site are a lot better than any site one can observe from at the peak, there is only one light dome at this site. It’s in the Southeast ( Santa Rosa ) and would not pose to much of a problem unless you wanted to work that lower part of the Southeastern sky, and if any fog were to cover Santa Rosa it would cover you as well.
The sky conditions were pretty good early in the evening, lots of detail could be observed on the Moon although there would be intermittent upper atmospheric fluctuations that caused the view to wiggle, there was also some detail showing on Mars but not much. After it got dark and while the Moon was still up I was bagging 12th mag galaxies and looking at the brighter stuff trying to pass time until the Moon set.
I will say that this place is nice and dark, When we were up at Blue Canyon last week I was able to split Epsilon Lyre naked eye. It was the first time I had tried that and was surprised at being able to do so, as were others at Blue Canyon that night. Paul and I were able to repeat this feat at Sonoma Lake last night before the moon set!
Unfortunately, as the Moon was on it’s way down we could see that there were some high clouds moving in, this fact spoiled what would have been a very good night of observing, because along with the clouds came the wind. The sky conditions deteriorated fast down to about 7 arc sec.
This site has good possibilities, but it is too early yet to give it a thumbs up. My main concern is the wind. We need to determine if the winds in this area ( I would guess 15-20 mph last night ) are common, or seasonal or an aberration.
I will be going back to Sanoma Lake to check these things out and will report what I find to the group.
By the way, if it turns out that that the winds we experienced last night were an aberration, this would be a great site for a large star party.