March 15, 2010: Lake Sonoma

Carter Scholz

15 Mar 2010. Lake Sonoma. 12.5" Dob. Steve Gottlieb and I met in Healdsberg and ate at Fitch Mt. Eddie's. The sky looked very unpromising. Bands and bands of cloud amounted nearly to overcast, especially in the west and north, with just a bit of blue overhead. But having driven the 90 minutes, we decided to go on to LS and hope for the best. I hadn't been under dark skies since November. As the sun set, there was no visible improvement, though overhead looked a bit better than the horizons. We set up anyway, a bigger deal for Steve with his 18" Starmaster than for me. All through twilight the sky looked worse than a bad Berkeley night. Only three stars (including Polaris) in Ursa Minor!

By full astro twilight, about 2045, the west began to look good. The winter Milky Way was visible, and surprisingly the zodiacal light was punching through brightly, all the way from the horizon into Taurus. From Cass to CMa and overhead looked good, though the north and east continued awful; you could barely see the back end of Leo. Luckily my planned targets were in the usable part of the sky. I'd anticipated so-so conditions, and so printed out finder charts for open clusters in Luginbuhl & Skiff, mostly near Ori/Mon.

I was trying out my new 8mm Ethos for the first time. A big step up in FOV and sharpness from my Vixen Lanthanum 8mm. 200x is a sweet spot for this scope. With the Ethos I have 30 minutes FOV (twice the Vixen's area). The only downside: it's a little trickier to estimate the size of objects, since I can't see the field edges without moving my head!

Seeing varied from good to fair. Early on I had four stars in the Trap, rather solid, with glimpses of E, and I had the feeling that transparency rather than seeing was blocking F. Mars showed good detail but has become quite small. At 2030 it seemed to me that I could see both polar caps, or at least two distinctly light areas at north and south limbs each hard up against two darker areas, Acidalia and Argyre/Valles Marineris. (BTW, what IS the canonical up-to-date source for the names of Martian surface features?)

Transparency worsened after 2300, and we packed and were gone before midnight.

• 1624: OC Per: 5 or 6 stars in angled string resolved in a small 3' patch; DSS shows nebulosity, but none observed.
• King 17: OC Auriga: a small 3' faint unresolved glimmer N of a chevron of three brighter stars.
• Stock 8: OC Auriga: tucked under bright chevron of 3, 10' long sparse string of about 13 unequal stars with a slight glow of unresolved.
• 2112: OC Ori: fairly dim 10' string of about 12, sparse, more or less even brtness.
• 2141: OC Ori: diffuse 8' patch with little resolution, perhaps 12 faint stars.
• IC 2157: OC Gem: near M35; sparse, in two separate lobes each about 5'x10' with a 3' gap; southern lobe a bit more populous, 20 vs 15 stars resolved. (Urano shows IC 2156 and IC 2157 here; IC 2156 may be just an asterism.) N2158, a compact 5' hazy OC drifted into view on the very edge of M35.
• Skiff J0614.8+1252: OC Ori: about 15 stars resolved, faint; either direct vision or completely invisible depending on passing cloud layer.
• 2236: OC Mon: one star prominent (fg?) over indistinct fuzz; 7-10 stars resolved briefly in lozenge about 2'x5' when transparency cleared.
• 2254: OC Mon: v. compact, faint, 4-5 resolved.
• 2259: OC Mon: 5' patch of mixed mag over haze, about 10 resolved.
• 2269: OC Mon: sinuous chain, about 20 resolved.
• Cr 115: large, 15'x5' 35-40 res, xmas tree shape.
• 2302: OC Mon: loose, large, 20 stars eq brt.
• Berk 28: one prominent star (fg?) 7 or 8 resolved in very small 2-3' faint glow.
• 2309: hazy patch irreg, 8', about 15 stars resolved.