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by Jay Reynolds Freeman
On the evening of Saturday, May 8, 1999, I hauled Harvey, my white Celestron 14, to central California's Fremont Peak State Park for an evening's observing. I had been to the Peak the night before, with my six-inch Astro-Physics refractor, and had been forced to quit early by increasing moisture and fog. Similar atmospheric conditions obtained at dusk, but notably less breeze gave hope the fog would stay low.
When I first bought my C-14 some twenty years ago, one of my first observing programs with it was a Messier survey. On recommissioning it last summer, I decided to do one again, just for fun. Now I was almost done, so as twilight rose from the eastern sky, I lined up finder stars in northern Virgo and set off into the realm of the nebulae.
I usually start off on the northern Virgo Messier galaxies by finding the north-south trio of stars that includes rho Virginis -- easy in any finder -- and sweeping north for M60 and M59. A tad further a degree west lies M58. From there, M90 is a bit over a degree north, or M89 is about a degree north northwest. Another westward sweep from M89, for somewhat over a degree, gets me M87. M86 and M84 lie about another degree west northwest, and then I walk out Markarian's chain to find M88 and M91.
On this night, the search worked well, and I found all the galaxies in short order. I was lazily using a 40 mm Vernonscope Erfle eyepiece, which gave 98x -- rather less magnification than is optimum for galaxy work with so much aperture, but the nice wide field was convenient. By coincidence, that is very nearly the same magnification that I had used for the same galaxies on the preceding night, with a six-inch Astro-Physics, and the similarity dramatically underscored how much finer the C-14 is for deep-sky work. Even with old coatings and a large central obstruction, the big Schmidt-Cassegrain gathered enormously more light than the refractor. In consequence, the view was vastly better.
I recently bought a portable electronic thermometer and relative-humidity indicator from the gadget shelf at Radio Shack, and had it sitting on the electronics box of my Losmandy G-11 where I could keep an eye on it. After the sun was firmly down, things settled at about 50 percent relative humidity and a temperature of not quite 10 C, and stayed there a while. But as I worked Virgo, I felt a change in the air, and looked again. The temperature had dropped to 3 or 4 C, and the humidity was rising. Wisps of fog sloshed up and down in the deep valley to the south of the park ranger's yard, where I had set up. I increased the power to my Kendrick anti-dewing system, and kept observing. At intervals of a few minutes, thin layers of fog crept over the viewing area, but they were scarcely more than a few meters in height, so that the transparency near the zenith remained high, and with the anti-dew system on on "fricassee", the corrector plate stayed clear. I dug out some spare gloves and draped them over the objectives of Harvey's two finders, since I was not immediately using them as I continued to star hop. The relative humidity meter climbed to 98 percent. Presently the fog thickened to the point where the stars above were fuzzballs, and the nearby top of Fremont Peak disappeared entirely, aircraft warning lights and all. The corrector plate was still clear -- I'll have to try that Kendrick underwater some time -- but there was nothing to look at for the moment, so I covered the optics, got in the car, turned on the motor and heater to get warm, and drank coffee.
After twenty minutes, the hint of sea breeze that had brought the fog upslope diminished. The white blanket settled back into the valley and stabilized. The temperature stayed at 3 C -- what brings people to California must be the cheese, it certainly isn't balmy spring weather -- but the relative humidity started downward and kept dropping as the sky cleared. I went back to the eyepiece.
There are a lot of little galaxies around the bright Messier targets of northern Virgo. NGC 4387 and 4388 are two of the easiest to locate. NGC 4388 forms the southern tip of an equatorial triangle whose other two points are the much brighter M84 and M86; it is an obvious edge-on spiral even in telescopes much smaller than a C-14. NGC 4387 is at the center of the same triangle, and is fainter still. These four provide a handy and unambiguously positioned set of test objects for determining how much you can see. Their stepped sequence of brightnesses also stimulates the imagination into thinking about all of the still fainter galaxies that you cannot see, that go on to the end of space and the beginning of time.
A fainter and more compact trio of small galaxies lies south and east of M86 and M84; NGCs 4431, 4436, and 4440 are about a degree west of M87, just north of several eighth to tenth magnitude stars. They were relatively easy in the C-14.
Markarian's chain contains seven quite bright non-Messier galaxies and several fainter ones. The toughest that I associate with the approximate path of the chain are the closely adjacent NGC 4446 and 4447, not far west of the more prominent NGC 4459. I think of these two perhaps as bits of gravel kicked up by some previous amateur astronomer skidding around one of the sharp curves in the chain.
I worked north to M98, M99, and M100, all within a few degrees of naked-eye star 6 Coma Berenices. There are plenty of relatively bright finder stars to guide you to this trio, the only problem being that the local stars include several wide pairs that all seem to look confusingly alike. There are more galaxies here, too -- I followed a path of several that led all east and north to M85.
Next I found globular cluster M53, which showed granularity and incipient resolution even at only 98x. Nearby M64, the Black-Eye Galaxy, showed its namesake feature as a region of diminished brightness near the center of the object; it wasn't so much a black eye as a slightly grayish one. Then I went on to M63 and M94, in Canes Venatici. M94 is a very pretty galaxy -- I see a bright center surrounded by a glowing patch with a rather ring-like structure embedded in it.
By this time, Mars was getting well up in the southern sky, so took a look at it. I had a new eyepiece to try out -- a Pentax 5 mm SMC ED orthoscopic, and I decided to drop it in and see what was what, even though I suspected the seeing wasn't up to handling 782x in a 14-inch telescope. I was right about the seeing -- my first view of Mars showed no detail whatsoever -- but I decided to be patient. A few minutes fiddling with the focus gave a hint that now and then, things were going to settle down a little, and though they never did get good enough to make full use of the high magnification -- not even as good as for the lower-magnification observations of Mars that I reported a few weeks ago -- nevertheless, I got a few good views.
The longitude of the central meridian of the planet was about 90 degrees (Areographic) when I started observing, and increased by some 15 degrees over the next hour or so. The face of Mars presented was relatively featureless. The tiny polar cap was the most obvious marking, followed by whitish Chryse, just disappearing around the limb. There were dark markings stretching from the polar cap toward Chryse -- that's Boreum Mare, Mare Acidalium and Niliacus Lacus -- and in moments of better seeing, they broke up into spots and blotches. I could detect a dark marking at about 90 longitude and +40 latitude, and, toward the end of the hour, the white spot of albedo feature Nix Olympica. Solis Lacus, sometimes known as the "Eye of Mars", was visible as a darkish oval, and the dark markings to the (Areographic) east of it gave rather the impression of an acute chevron that widened out to the west, as if to embrace Solis Lacus itself. The chevron is comprised of Erythraeum Mare and some of its extensions. The Eye of Mars was rather less visible than the eye of the Black-Eye Galaxy, but I suppose that is only reasonable, considering that it is some ten to the fifteenth times smaller.
A fellow observer wandered by from another group of telescopes for a look at Mars through mine. She confirmed that the seeing wasn't very good, by saying that a five-inch Takahashi was showing detail similar to what we could see through the C-14, and we found yet another reason why it is difficult to compare telescopes effectively: She was not familiar with the "touch" of Harvey's focuser, and what with the jiggles from the poor seeing, she had trouble getting the focus set right to take advantage of such moments of steadier air as there were. My C-14 has relatively little mirror shift, but there is enough slop in the threads of the focuser, and enough tendency for its movement to be a little erratic, that it takes some experience to set the focus well. My technique is to play around for a while first, to get a feeling for what the image looks like at varying degrees of defocusing on the night in question, then back off well to one side of good focus, center the object in the field of view, and sneak up slowly on best focus from that direction. If I overshoot, I usually find it quicker to back well off and try again than to go back and forth trying to bracket the target.
We did try some other eyepieces, 12 mm and 8 mm Brandons for 326x and 489x respectively. The seeing was such that to my eye, using lower magnifications did not give up any detail, but Mars is bright enough that I preferred the higher magnifications even though they did not show anything more -- they made what there was easier to see when it was briefly visible. Your mileage may vary.
I visited those other observers, and had a nice view of Omega Centauri through a 12-inch Newtonian at 60x and through a 5-inch Takahashi at 50x. The great globular cluster was showing resolution in both instruments. Before I left, the Newtonian also provided a look at NGC 5128, and we had a good view of the dark lane across the middle of this unusual object.
Wandering back to my own telescope, I tried 326x and 489x on M87, wondering if I could see the nuclear jet, but the seeing was rather obvious at those magnifications, so I am not surprised that I detected nothing. Then I put Harvey to bed, and drove home.