SJAA

Ephemeris

Report from Henry Coe

Gary Mitchell


We had the opportunity to spend Wednesday night, August 11-12, camping at Henry Coe to see the Perseid meteors. As meteor showers go, this one wasn't especially noteworthy, but the conditions for astronomy were fantastic! It's rare to have skies like this near the Bay Area.

The forecast was for low clouds and fog over much of Northern California. San Jose (at least at my house) was completely overcast. Such weather is very rare around here during this time of year. I thought the trip was going to be a bust. However, some of my previous experiences with "low clouds and fog" have been very positive. If you are high enough (e.g. Fremont Peak or Henry Coe) to be above the clouds, they block out much of the light from the cities. I've noticed that the seeing and clarity tend to be pretty good under those conditions too.

It turned out the clouds never got above about 1,500 to 2,000 feet, well below the camp area of Henry Coe. The cool marine air flowing on shore caused a fair amount of wind at first, but it settled down to a gentle breeze shortly after dark. The air was very transparent and surprisingly steady. Even more surprising since there were a few small camp fires going in the area. I suppose the breeze was sufficient to blow most of the turbulence way from where we were.

With the clear air and clouds blocking city lights from below, the conditions couldn't have been much better. Most of the lights from Gilroy were still visible, but not a problem. The Milky Way stood out well against an unusually dark sky for the location. Between catching the odd meteor, I had almost a dozen Messier objects effortlessly viewed in what seemed like no time at all.

After showing the globular cluster in Hercules (M13) so often at school star parties (around San Jose), now it was almost unrecognizable! It truly looked like a pile of salt-hundreds of individual grains glowing against a velvet backdrop-instead of the "faint fuzzy" I'd become accustomed to. And the Omega Nebula (M17), also called the "Swan Nebula," really did look like a swan in my small six inch. I was surprised at how much detail was visible.

The moral of the story: Clouds-the bane of astronomers-sometimes really do have silver linings. I'm glad to have been there for this one. Just watch for those words in the forecast: "LOW clouds and fog." Also, this being the first time observing from the camp ground area of Henry Coe, I left feeling rather good about this park for astronomy.


Gary Mitchell; last updated: October 04, 2007 Prev Next