by Jay Freeman
On Saturday, 3 February 2001, I took my Astro-Physics 10-inch Maksutov-Cassegrain, whose name is Gillian, to Fremont Peak, in the California coastal hills overlooking Salinas. I almost didn't recognize the place with a fat gibbous Moon in the sky -- I am not sure I have ever observed there with so much Moon. Yet weather conditions hinted at good seeing, and I was anxious to try some more high-resolution work with this relatively new instrument. I guess most of us are deep-sky observers: I was the only telescopist there.
The weather was unseasonably warm for winter -- temperatures stayed in the 50s (F). A blustery wind brought the wind chill down, and didn't help the seeing, either. After the telescope had settled in, conditions near the zenith were such that I could always see the Airy disc and at least the first diffraction ring of a stellar image, but both disc and rings were always in motion. Castor was a wide and trivial split in these conditions. Seeing deteriorated with increasing angle off the zenith toward the south, perhaps because the wind was out of the north and the line of sight southward passed over the high terrain of Fremont Peak itself. Persistence, was rewarded with occasional brief interludes of much better seeing, even down over the hilltop.
Jupiter and Saturn were well-placed as the evening began. I looked at them with 309x (12 mm Brandon eyepiece). I never know what to say about Jupiter except "gee, there sure was a lot of detail." Gee, there sure was a lot of detail. Saturn looked much as I have reported it before with this instrument in similar seeing. The Crepe Ring and the Cassini Division were easy, as was the broad minimum at the mid-point of the A Ring. I saw no "spokes" in the rings. There was the usual brownish belt in the south temperate zone of the disc, but I did not see an equatorial belt this time. The southern half of the southern hemisphere gradually shaded toward a more neutral and slightly darker hue at the south pole than at 45 south latitude.
The Moon was wonderful. Near the northern limb (Selenographic directions), the terminator had cleared the western edge of Sinus Iridum. Plato, was by then 20 degrees of longitude from the terminator, and I was a little surprised that I could easily see all five of the small craters inside Plato that are plotted in Rukl's atlas (chart 3). They were clearly visible as craters, not merely white spots or splotches of indeterminate nature. I also spotted a sixth interior crater, which is not on Rukl, near the one plotted in Rukl nearest to the center of Plato. I only spotted it because I was staring intently at the plotted one. I subsequently verified the additional crater on a Lunar Orbiter image, which also showed several other craters of similar size, that I could probably have spotted if I had been looking in the right places when seeing settled.
Further south, the rough terrain in and around Copernicus (Rukl 31) was beautifully delineated. This is one of my favorite areas of the Moon, and though I can only go by memory, I do not think I have seen it as well before.
Still further south, Ramsden (Rukl 63) was about six longitude degrees from the terminator, which was at a point where most of the rim of Gassendi (Rukl 52) was lit, but none of the interior. The "N" shaped trio of rilles adjoining Ramsden to the north was easy, as was the central part of a broad X-shaped sprawl of rilles centered about 20 Km southeast of the crater. I could not see the north and northeast extensions of the X, heading out across Palus Epidemiarum. I could, however, see the western portion of Rima Hesiodus, all the way to its charted terminus north of Capuanus (still on Rukl 63). South southeast of Gassendi, I could see as craters, several small craters not plotted on Rukl, in the general vicinity of Gassendi J and R.
I don't think I have ever had a better view of the Moon. I will have to try some more, at other phases.
I spent a long while staring at tough double stars. TAC's Jay LeBlanc had reported recent success with an occulting bar, and though I had made one long ago for some Meade research-grade eyepieces, I had lost mine. I improvised a bit, stuffing a flexed piece of blackened 3x5 card down the eyepiece barrel of my 8 and 12 mm Brandon, but the field stop of the Brandons is inside an inner tube, of lesser diameter than the main barrel, so I could not easily get the edge of the card stock to where the image was focused. I will work more on occulting bar design.
I split Sirius anyway. At 464x (8 mm Brandon), the seeing down over the Peak was sickly. Most of the time the primary was blurred out to where the Pup lives. Yet now and then, seeing settled, and I would get a sense that there was an Airy disc under all that glow. Occasionally there was a bright nodule at the right position angle and distance -- not a particularly aesthetic view, but a split of Sirius nonetheless.
Next I tried Procyon, at the same magnification. It was a lot higher in the sky, where the seeing was much better. Although Sirius ought to be a much tougher double, at least at its present separation, nevertheless, I found Procyon much easier to resolve. The companion was a bright fleck adjoining the outside of the first bright diffraction ring of the primary, dead on the correct position angle. I had never split Procyon before.
The AP-10 continues to perform well. I shall keep gloating about it as long as it does.