Last night was clear after a week of various parts of clouds, rain thunder and lightning. The more I observe, the fonder of objects in the sky I become. The fonder I become, the more I am affected by absences. It was no different tonight. Although I only observed a week ago, it seemed like months.
My target for tonight was once again Luna, which is starting to lose its grip on the dark sky. Not only is it waning, but it is also rising later and is much lower in the sky compared to last month.
Although I understand the cause, I was surprised and even disappointed by this: It would be very late before it rose high enough to get out of the worst of the bad seeing.
One of the things I was looking forward to seeing was "O'Neil's Bridge", showcased in the January issue of Sky and Telescope. This feature, which is not a bridge at all, is on the western (selenographic coordinates) side of Mare Crisium.
I took the scope out at 11pm. The scope temperature was probably about 66F. The outside temp was probably mid 40's to low 50's. After a 2.5 hour cool-down, the scope appeared to be close to thermal equilibrium. It might have come to equilibrium before this -- this is only when I started using it.
The first thing I looked at was the terminator at 310x, which ran approximately at 41-45 E longitude. Amazing detail leaped out at me as I 'flew' along the terminator from north to south. At one point I saw an amazing rille, which I suspect was Rima Cauchy, but I was not careful about identifying it.
After browsing the terminator, I searched for and could not find Mare Crisium immediately. Aaack! Crisis on the moon! This is the opposite extreme from galaxy hunting, where there is not enough detail visible. Here, there was too much!
I studied what turned out to be the area between Mare Tranquilitatis and Mare Fecunditatis (only 1/4 of which was in sunlight), trying to make it look like the edge of Crisium, but I could never quite succeed.
I spent a while trying to orient myself. I think part of my problem was that I started out observing at 310x. Finally, I thought I recognized Mare Serenitatis and Mare Tranquilitatis, with the prominent crater Plinius between them. I went to 119x, and everything was obvious, if reversed.
I was a few hours too late, and the entire Mare Crisium was already in shadow.
I find the view through the Mak with a star diagonal more confusing than through a newt, because the diagonal reverses the image left-to-right. Simple inversion is easily handled by simply inverting the chart.
Tycho, Copernicus and Kepler all had stunningly prominent ray systems.
Dew was heavy, but no dew appeared on the corrector. I did not even bother to uncap the finder.
Visually, I saw the tail of the Scorpius and Antares (the Rival of Mars). In the east, Cygnus the Swan was flying parallel to the horizon and I could see the Summer Triangle. Summer is a'comin'!
After a week of lousy weather, it was wonderful to be under the stars once more.
--------------------------------------------------------------------- Date: Apr 15, 1998 1:30am-2:30am PDT (0830-0930 UTC) Location: Backyard near Sacramento, California 121W 16', 38N 44' Instrument: Intes MK-91 9" f/13.6 Maksutov-Cassegrain Oculars: 26, 10, 7.5mm Sirius Ploessls Seeing: 5/10 Transparency: 6/10 Limiting mag: ~4