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by Matt Tarlach
Last Wednesday, Allan Keller & I met at the Wragg Canyon site near Lake Berryessa for a short observing session. My wife Belinda came along, and we were joined by a friend of mine who is just getting into astronomy, and his son. I got there a little before 8, and had a nice talk with the owner of the site, Judy Spears. She is leaving shortly on a trip to the Far East, but repeated her invitation to come down and use the site whenever we could. I think she really likes the idea of people enjoying the stars from her field!
Allan brought his Tele Vue original Genesis, and I had my 12.5" Astrosystems dob. It being a short session, and considering our novice guests, we spent most of our time looking at brighter showpiece objects, and getting a feel for the site. The canyon walls are fairly high, blocking as much as 30 degrees to the East and West. There are some oak trees to the South that rise about 20 degrees, with a notch right above Judy's house that allows a glimpse of the lower part of Scorpius. On the plus side, there was no wind at all in the sheltered location. The weather was pleasantly warm and the skies clear with low humidity - it was a great night that likely showed the site at its best.
We did a Messier sampler, often comparing the views in the two widely different scopes, and had a couple of especially nice views of the Veil. In Allan's 4" f5 with a 40mm Orion Optiluxe and Ultrablock filter, both sections of the Veil were visible and the circular shape of the whole structure clearly seen. With a 22mm Vixen Wide-angle and O-III filter in my 12.5" f6, we zoomed in to check out the detail in the streamers and knots of the nebula. Around midnight we capped the evening by looking for Neptune. I tracked it down in the 12.5", and gave my new 6mm Radian first light. It was a very pale blue, with limb darkening clearly visible in moments of steady seeing. Allan was running Starry Night on his Mac notebook, and we used the program to pin down Triton. It was easy, once we knew where to look - there were a couple of dim stars near Neptune that had me confused at first. Earlier in the evening, Starry Night had helped us catch the ISS passing overhead, and a brilliant Iridium flare that we guessed reached mag -4 or perhaps a little better from our location.
The sky darkness was good, a lot better than Montebello, but not as good as I'd hoped. When I first heard about the site about 3 years ago, it was hailed as a true "dark site" location by a fellow who has observed from the Sierra and the Oregon Star Party. Either he took a little poetic license with the description, or else the rapid development of nearby Fairfield and Vacaville have brightened the sky considerably since he was there. There were noticeable light domes rising about 30 degrees to the Southeast and South, washing out many of the fainter stars of Scorpius, Sagittarius and Capricornus. I'd put the naked eye limiting mag in Sagittarius at culmination around 5. M7 and M6, usually easy naked eye objects from anyplace I'd call truly dark, were invisible. Overhead, and at the other compass points, it was a lot better. I was seeing mag 6 stars at the zenith, and my vision has never been that great - when we've done group star counts at MB and Lassen, I've always come up 3 to 5 tenths behind the keenest eyed TAChies. M13 was detectable naked eye, though not as obvious as from Blue Canyon or Fiddletown.
Overall, I think the site is well worth consideration as a close-in option for those of us in the Valley or the Northeastern Bay Area. The security of the site, on private property with an enthusiastic stargazing owner, makes for a comfortable and peaceful evening. The access roads are all good, down to the last 100 yards of gravel driveway. I can see myself using the site in winter, when snow and cold weather close the higher elevation sites in the Sierra and Gold Country.
As I said, Judy extended her invitation for anyone who would like to come up and observe from the site. Right now there is about a 20 by 30 foot area of her field mowed, enough for 3 or 4 scopes. Since Judy is going to be away for the next couple of months, I am a little hesitant to post her address and directions directly to the list. If anyone would like the specifics, just email me and I'd be happy to send the info privately.