by Shneor Sherman
Clear Sky Clocks forecast tolerable viewing conditions at Lake Sonoma for the night of February 17 from 9 p.m. to 3 a.m. Since the 18th is a holiday for me, and I missed last Saturday night, I decided to revisit Grey Pine Flat at Lake Sonoma. I planned to arrive well before moonset, and in fact arrived at 9:20 p.m. after a journey of just under 2 hours. The crescent mood was up, and the sky was very clear and dark except for clouds to the East. I set up and at 10 sighted my finder at the moon, which looked quite 3-dimensional and spectacularly sharp in my 30mm Widescan II with Visual Paracorr.
While the moon was up, the sky was extremely transparent and still. The seeing was 8/10, and transparency was also about 8/10, maybe a bit better. Shortly after the moon set, however, a fairly narrow band of clouds blew from West to East, bringing with it unwanted moisture and much colder air. While the clouds exited over the course of less than hour, the moisture stayed, and I found myself constantly using my hair dryer and portable battery to un-dew eyepieces and even my secondary. I'd wonder why images were so soft and finally I checked my secondary - the outer third was dewed over. Eventually, by 1:45 the moisture was so bad, I decided to pack up, but not before some nice views. My table had little puddles of water on it, as my eyepiece case. There was no wind. I'd say the seeing deteriorated a bit to 7/10 and transparency fell to 6/10 shortly after moonset.
| Equipment |
18" dob on equatorial platform, Rigel Quickfinder 30mm Widescan II 20mm Nagler 13mm Nagler Type 1 all used with Visual Paracorr Lumicon OIII filter Lumicon UHC |
|---|
While the moon was still up I had a very nice view of Thor's Helmet, one of my favorite winter objects. I viewed it with the Widescan II and 20mm Nagler, and OIII filter.. The shape reminded me of Mickey Mouse, with a long, wispy beard. The 20mm showed a bit more detail, but contrast was muted. I then viewed M42, which surprisingly showed good color in both the Widescan and 20 Nag. E in the Trapezium was distinctly red when I used my 13mm Nag. I moved to Jupiter, where, with the 13mm two wide bands, one with a whitish oval were visible near the middle of the planet, while at least 6 additional narrow dark bands were visible. At least one looked crooked. I then had a quick view of M81/82, where despite the low contrast, I thought I saw very faint, large arms around M81. Although the moon was lower, it still interfered with the view, and I could also see a narrow band of cloud just over the rise to the West. So I turned to Leo, where M65, M66 and NGC3628 were a lovely trio in my 30mm. N3628 looked very clear, so I viewed it with the 13mm. Contrast did not improve, however. I then moved to another trio in Leo, N3608, N3607 and N3599, then on to another group, three in a line plus one, N3686, N3684, N3681 and N3691. The moon had set by now, but clouds were overhead and to the East and North. Where the sky was cler, there was less contrast then when the moon had been up. It was past eleven and I took a break.
I resumed in Coma Berenices, with N4656, a long, fat cigar of a galaxy, then Canes Venatici, where I viewed M94, N4625, N4618, N4490, N4485, N4868, N4914 and M63; N4889 and N4874 also, a nice tight duo. (Every few minutes, I had to un-dew my eyepieces with the hair dryer.) A quick view of M51, which showed the spiral arms clearly in both the 30mm and 13mm, and the connecting arm to N5195. As I was in the neighborhood, I popped an OIII in and had a qhick view of the Owl Nebula; the "eyes" were visible with averted vision in the 20mm. Since I had the filter in, I checked M42 again. The view had been better with the moon up, although the sky looked very dark, stars were not as bright as they had been earlier that evening.
The band of clouds had disppeared to the East some time ago, so I turned toward Virgo, where galaxies are like grains of sand, so to speak. I began with N4595, and quickly got lost from there, as the number of galaxies lost me. Suffice it to say that I viewed at least 40 additional galaxies in Virgo.
I then moved back to Ursa Major, and looked for galaxies in the bowl of the Dipper, but found nothing. I thought that the battery in my finder was dead and began replacing it, when I noticed that the plastic window was completely dewed over. Hair dryer time, again...
I revisited a few earlier views for comparison, some were a bit better near the zenith, but everything was becoming quite waterlogged, so I decided to pack it in at 1:45.
It was a damp night, but a good quick fix.