A Rogue Wed at Henry Coe

5/3/2000

by David Kingsley


I didn't get the car loaded till almost 8:30 pm last night, and couldn't get online to post a final decision about observing. However, I suspected that the encroaching marine layer would bury Montebello ridge, and improve Henry Coe State Park, so I headed south for some midweek new-moon observing.

I could see low clouds were billowing over the coast range on the drive down 280. Skies stayed clear at Henry Coe to the east, south, and zenith all night, with some high cloud bands to the west. Fog partially filled the valley as expected, temperatures stayed in the mid 50s all night, and a light, steady breeze was present but managable by setting behind the car.

I saw an enjoyable mix of 18 new and 45 total objects, including a mix of Herschel 400 targets, volunteer galaxies on the way to H400 objects,a few double stars,some favorites from the Messier list, and the 3C273 quasar. 3C273 has been on my list of odds and ends list ever since I asked a question on TAC a year or more ago about the most distant object people had observed through their telescopes. Jamie's report stimulated me to finally look it up in the 7 inch Starmaster. I enjoyed soaking up all those ancient photons on a retina that evolved billions of years after the light left the quasar.

There has been some recent TAC discussion about limiting magnitudes at different locations. Around midnight I broke out the HB Astroatlas to make an estimate for last night. (One entire set of low resolution charts in the HB atlas has magnitudes written alongside naked eye stars, making it possible to gaze at any sky region and check the faintest star you can see.) Using this method, I came up with a limiting magnitude of 5.8 around Polaris, and limits of 6.1 or 6.2 higher up in Ursa Major and Bootes. The faintest stars listed would flicker in and out with averted vision, and stars listed as 6.3 or 6.4 were never seen. This is the first time I have tried this, and I expect more experienced observers with less astigmatism in their eyes might have seen deeper. On the other hand, eye doctors, family, and friends have told me that my pupils dilate more widely than most, so I may come out about average overall (light gathering varies with square of pupil diameter, but my astigmatism is at its worst when full pupil diamter is being used). I'll start looking more regularly so I can compare conditions from night to night for my own set of eyes.

Mark's more qualitative methods were more difficult to use last night. However, by the criteria of being hard to see the faces of other observers, it was pitch, pitch black at Henry Coe. I ended the solo session about 2:15 am, and drove home happily full of photons through the fog-filled valley below.