Some Suburban Observing

1997 Mar 18

On the evening of March 18, I set up my Intes MK67 6-inch f/10 Maksutov in the driveway of my home in Palo Alto, California. A long thermal settling time means the Intes is not a telescope to take outside for quick looks, but I pre-cooled by putting the optical tube assembly into the back of my car for an hour or so, while I was doing something else. In our unseasonably warm weather, that allowed sufficient cooling time that the instrument was ready to perform as soon as I had installed it on the mounting.

My main goals for the evening were the Moon and Mars. I look at the Moon fairly often, but mostly with smaller telescopes. I generally observe with the Intes only at dark-sky star parties, and for those, the Moon is usually not up, or at least, not very far up, so I haven't done much lunar observation with it. Seeing was acceptable but not perfect -- the Airy discs and at least the first diffraction rings of bright stars were always visible, though generally in motion.

I can get lost in my imagination looking at the Moon. I have been a lightplane pilot, and one of my reactions to looking at terrain, or images of terrain, from above, is to think what it would be like flying down in it. How would I navigate? What would be good landmarks and reference features for pilotage? What would I use for air? (Well, never mind...) Some of the maps for flying have a resolution of a kilometer or two, just about the linear resolution of a good six-inch looking at Luna, which encourages the feeling of similarity, which is a very odd sensation.

At 300x, the view of the Moon was very rewarding. The terminator ran roughly down 30 degrees west Selenographic longitude. The Riphaeus Mountains were strongly highlit, though further to the (Selenographic) east, Fra Mauro had just about faded into obscurity against the flatlands of Mare Cognitum. It was fun to look at the terracing and slumping in the great crater Copernicus -- there are slumped landforms in the coastal hills near San Francisco, on a scale that is somewhat smaller. Thus the physical geography looks very familiar, which is very strange when looking at another world.

On the terminator south of the Riphaeus Mountains, I spotted a north-south system of rilles that I was not familiar with. A glance at Rukl's Moon atlas showed that I was looking at the old crater Hippalus, just on the terminator. The Intes showed nearly all the detail that Rukl did. Under the grazing illumination, Hippalus seemed to have a very irregular floor.

I looked at Pitatus and Hesiodus -- I had watched the Hesiodus sunrise ray the previous day. Though this area was by now well illuminated, shadows still persisted near the gap in the common wall through which the ray emerges.

Further north, the sunrise line crossed Sinus Iridium. Laplace Promentory was prominent, as were some of the wrinkle ridges crossing Mare Imbrium to the south. The Straight Range, Teneriffe Mountains, and Pico were all well-illuminated and full of detail.

Mars was rather disappointing. The Intes showed a fair amount of shadowy detail, but on the whole the disc of the planet was washed out and appeared rather obscured, and the planet's color was much yellower than I am used to. Does anyone else think there is obscuration at present in the Martian atmosphere itself?

I finished off the evening by looking at a couple of moderately demanding double stars. Otto Struve 256 was an easy split, but the much similar Burnham 929 merely appeared elongated -- perhaps it has closed since the most recent measurement. All three components of 35 Coma Bernices were no trouble -- the wide pair is very easy, the narrower one similar to 78 Ursae Majoris, which I also split.

It's nice to be able to do some interesting astronomy under light-polluted suburban sky. I enjoy chasing down faint fuzzies, but the popularity of that side of our hobby should not deter anyone from seeking out things that are easily detected in brighter conditions.

Jay Reynolds Freeman; last updated: 1997 Mar 20