February 17, 2010: Henry Coe State Park

Peter Natscher

It's amazing how one night can make a difference in weather for doing our night time astronomy activities. Just as the weather reports had forecast, the four of us enjoyed totally clear skies by 7pm after much anxiety over the day's cloudy skies. The entire evening's conditions up at Henry Coe State Park were a light breeze, temps in the high 40s, no dew on our scopes, NELM of 5.5, and 1 arc-sec (sometimes less) seeing above 45° from the horizon. The sky seemed a bit bright, but I'm not used to this usual condition of Coe SP usually observing from darker sites that don't expose my eyes to direct city lights (San Jose, Gilroy) as Coe does.

Up at Henry Coe State Park, I accompanied three imagers: Paul Duncan, Rogelio Andreo, and Al Howard until I left at 1:30am.

I enjoyed observing a variety of the sky's objects: planets; galaxies; emission, reflection, and planetary nebulae with my 24" f/3.7 Starmaster FX with drives and making sketches with written descriptions of some of the observed objects.

Observing Highlights:

Beautiful sunset by 5:50 pm.
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Venus spotted by 6:15 pm naked eye in a bright and colorful twilight; a telescopic look at Venus at 115X showed Jupiter within the same field of view -- only 45 arc-minutes away!
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Late twilight 7pm, bright and colorful Mars showing a substantial white north polar cap, dark gray sharply outlined surface detail (Syrtis Major was on the meridian) and much white atmospheric clouds covering the planet's east and west limbs (it's morning and evening clouds). Mars is so bright in a 24" scope, it has to be filtered down a bit to see the surface marking well. I was using a Baader Astronomy Planetary Filter which lowers the glare without filtering out the planet's true colors. The <1 arc-sec seeing supported the 24" Starmaster resolving power well.

I got back to observing Mars again just before deciding to pack up at 1:30am since this was probably the last time I'll see Mars this well and big until the next opposition in two years. Who says you can't see fine planetary detail with a big shorter focal length Dob. The air conditions and seeing was good enough for the 24" scope to discern sub-arc-sec detail on the Martian disk.
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NGC 2207 & IC 2163, Canis Major, M 12.2/11.6, two interacting face-on galaxies, good spiral structure in 2207; 2163: shows only as a circular patch.
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J320 (Jonckeere), Orion, Planetary nebula, M 9, 11' x 8', small blue oval planetary with mottling detail noted at 400X.
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J900 (Jonckeere), Gemini, Planetary nebula, M 12.2, 8' dia., small blue oval planetary with irregular outline and varied brightness within at 400X.
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M 1-7 (Minkowski), Gemini, Planetary nebula, M 13, 29' dia., small round blue/grey disk of even brightness, OIII filter brings out mottled detail within.
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IC 418, Lepus, Planetary nebula, M 10, 12' dia., small round planetary nebula appearing warm in color (unusual lavender & reddish color). Evenly bright with bright central star. No detail within disk.
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M 1-1 (Minkowski) Andromeda, Planetary nebula, M 14.1, 6' dia., Small almost stellar planetary with oval shape and slightly brighter center.
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Jones 1, PK 104-29.1, Pegasus, Planetary nebula, M 12.1, 5' 32' dia., large grey-colored circular planetary with incomplete ring - opposite opposing lobes of varied brightness. Two large arcs with faint detail filling the large center area.
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Abell 2, Cassiopeia, Planetary nebula, M14.1, 40' dia., grey circular patch of even brightness with two field stars overlapping the disk.
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IC 289, Hubble 1, Cassiopeia, Planetary nebula, M13.2, 48' dia., faint grey circular planetary disk, averted vision shows some variation in brightness, central star blinks with averted vision.
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Sharpless 2-235, Auriga, reflection nebula, OIII filter brought out most of its large oval shape nicely, looks like a roundish cloud with scalloped edges.