by Jay Freeman
As summer approached, I wondered what to do at the Lassen Star Parties over the 2001 July and August new Moons. Lassen is primarily a deep-sky place -- I have never seen seeing good enough at our usual observing sites in the National Park, to set up a large high-resolution telescope. Yet I had completed my last big-iron deep-sky observing program, and had not thought of any new worlds to try to conquer. I ended up doing my observing, at both events, with smaller telescopes mounted on my modified NexStar 8 mounting, or with large binoculars.
Furthermore, my travel planning was complicated by an elderly cat who needs regular medication for a chronic condition, so I couldn't stay away from home for long. I ended up making five round trips between the Bay area and Lassen this summer, instead of just two, to give Percy his pills. (He was fine.) I was reluctant to haul expensive, fragile equipment hundreds of extra miles, and there was no place to leave it.
I have described my NexStar project in other postings; its ease of setup and computer-controlled slewing facilitate working down a target list rapidly, and my modifications have allowed me to use almost every small telescope I own on its mounting. During the second calendar quarter of 2001, I developed and debugged these new capabilities, and now it was time to put them to use.
For July, I brought my NexStar 8 mount with two OTAs -- the C-8 that came with it, and my Vixen 70 mm fluorite refractor. I also brought a big binocular, but I will get to that later. As part of shaking down the NexStar 8 mount, I had started a Messier survey and a Herschel-400 survey with the 8-inch, and had continued an existing 70 mm Herschel-400 survey that I began with a conventional altazimuth mount. I continued these programs in July, and finished the one with the 70 mm.
The difference between my Vixen 70 mm refractor and my Vixen 55 mm, "Refractor Red", with which I had previously accomplished a Herschel-400 survey, was noteworthy. There were a generous handful of objects which were very difficult with the 55 mm, even in quite dark sky, but with the 70 mm, none were truly challenging in excellent conditions. It was fun to use this tiny refractor with the high-tech NexStar mount. I bought a set of aftermarket brass focuser knobs for it, which add two pounds near the aft tube end, and bring the center of gravity of the OTA far enough back so the tube clears the mounting without additional counterweights, even pointing straight up. The 8-inch OTA sometimes seems a bit too much for the NexStar 8 mount, but the Vixen 70 feels well-mounted there.
It should surprise no one that Messier and Herschel-400 targets are easy with an 8-inch aperture, particularly in sky as dark as prevails at Lassen. I pushed the two surveys with this instrument around into the autumn sky, but will have to wait till the area south of Orion is well-placed to finish them.
For these observations, I found myself using a Vixen 8-24 mm Zoom Lanthanum eyepiece. It does not provide as much throughput as non-zoom units with fewer air/glass interfaces, but it has become a workhorse for the NexStar mount, which does not always point accurately enough to put an object in the field of view at the magnifications I use for deep-sky work. It is handy to be able zoom out -- and widen the field -- for slewing, to find the object, then increase magnification for a better look. I view most H-400 galaxies at or near the minimum magnification the eyepiece will deliver, but use more to look for hints of resolution in globular clusters and in some open clusters. I also find it occasionally useful to adjust magnification in small increments, to find just the right value for difficult low surface-brightness objects.
It is fun to twist the "zoom" ring on this eyepiece and watch the stars rush out from the center of the field. I keep thinking, "Quick, Chewie! The jump to lightspeed!"
In August, I had my 90 mm Vixen fluorite on the NexStar 8 mount, for a new Herschel-400 survey. I got it brass focuser knobs, too, but even so, the center of gravity is not far enough aft for the OTA to clear the mount -- they collide when I slew to objects more than 60 degrees up. That actually isn't much of a problem -- there is plenty of sky to look at, and an evening's observing is time enough for objects to get clear of this rather large "Dobson's hole". In four nights, I logged about 275 of the Herschel 400. I was using the Vixen Zoom Lanthanum again: It was most handy early in the evening. I was able to observe some brighter H-400 galaxies in late twilight, as they were about to sink below the horizon, using considerable magnification. As the sky darkened, I backed off the magnification in small increments, and worked fainter and fainter objects.
I tried the 90 mm on some more difficult targets, as well. At 101x (8 mm on the Vixen zoom), I was just barely able to see the brightest globular cluster in the Andromeda galaxy, NGC 224-G1, at the limit of averted vision. At the same magnification, I spotted all four of the well-known companion galaxies of NGC 7331; namely, NGC 7335, 7336, 7337, and 7340. Then I took a look at Stephen's Quintet, which I had observed before with the Vixen, but in less pristinely dark sky. I played with magnifications, and found best viewing at about 65x. I could see NGC 7319 and 7320 separately, popping in and out at the limit of averted vision, in noticeably different locations. The merged combination of NGC 7318A and 7318B popped in and out similarly. I could see something at the approximate position of NGC 7317, too, but could not distinguish the galaxy from the star near the same line of sight. This Stephen's Quintet observation was a high point on my "how much can I see with how little aperture" curve for this object.
For both star parties, I brought my 25x100 Orion binocular. One night in July, I had a fine time with it, scanning the central Milky Way. Its combination of field of view and magnification makes it wonderful for exploring the network of dark nebulae that lie between us and our galaxy's central lens. In August, I was about to haul it out for some similar work, when I realized that another TAC member had set up a Vixen 30x125 next to my car, and wasn't using it much. (I don't believe there is more than one of those instruments in TAC, and I think we all know who owns it, but I will continue my habit of not naming people who have expensive items in their garages, in text files that might end up on the internet.) So I mooched! In an hour or so with this instrument, I logged somewhat more than 50 Messier objects, and a handful of other things as well. The steady mount of the big Vixen augmented its larger aperture to yield much nicer views than my 25x100. Yet its low magnification left it doing less well on many deep-sky objects than was my Vixen 90 mm refractor -- I could not see any of the companions to NGC 7331 with the 30x125, and Stephen's Quintet was an unresolved blob of fuzz.
I stayed in rustic quarters north of the Park, as usual, and as usual crowed mightily about the virtues of soft beds, curtains, space heaters, hot showers, and little noise. Seriously, off-Park lodging has worked out well for me; I don't seem to get as tired as many folks staying in tents. And it sure is nice to have a soft bed, curtains, a space heater, a hot shower, and little noise...
I found a new shortcut to the north side of the park, in July, and may as well mention it here. Leave US 5 at Jelly's Ferry Road, which is the second or third exit north of Red Bluff, and well marked. Follow it north and northeast to Ball's Ferry. (Jelly's Ferry seems to be just a bridge.) At Ball's Ferry, bear right onto Ash Creek Road, thence to Dersch Road, and turn right again to get to state 44. I don't think this route is any shorter than getting off 5 at Cottonwood and taking the Ball's Ferry road from there, but there is enough congestion at Cottonwood that the Jelly's Ferry route might take less time. In either case, it is a pleasant, scenic country road, and lots of fun to drive.