6:30 p.m. 3 January 2000 (0230 4 January 2000 UTC)
Perhaps you didn't notice, and judging by the number of e-mails I didn't
get in my mailbox, you didn't, but I didn't post very much during the
recent holiday break, owing to my moving into a new house with a somewhat
higher limiting magnitude. (Yes, that's why I bought it.
Anyway, while we were staying at our halfway house, my wife Debby and I exchanged gifts, naturally, and I received, much to my surprise, a C5+ tripod and a Radian. Now, I have a confession to make. I enjoy that I don't use a lot of money in my astronomical pursuits—a healthy amount, but not as much as many. It was fun going out and buying a Black and Decker workbench for my "tripod." But I must admit, it warmed the cockles of my heart to receive the tripod. They weren't going to be available for much longer, so she got it at the right time. ($180 or so, USD, at Woodland Hills Camera and Telescopes, which also carries some remaining stock of the C5+.)
What was more touching, and please don't retch on the screen, is that she didn't go in knowing much about astronomy equipment, but if there's anything she can do well, it's researching. Eventually, she came to the conclusion that the Tele Vue Radians were well-regarded (to put it mildly), so she bought one of those. She wasn't sure what focal length to get, so she got the shortest—3 mm. The C5+ is a f/10 scope, so that's a bit too short for most nights, yielding something over 400x, so with her blessing, I exchanged it for the 6 mm version.
I took them out with Opus, my C5+, last night (3 January 2000) for a preliminary look-see. The C5+ wedge attaches to the tripod using three bolts that come with the C5+, not the tripod, so if you've got one without a tripod, you may need to fish them out. (I have extras, though, so they're standard bolts—I'll post the type here when I find out what they are.) This process is not as nice as it is for the Nexstar 5; doing this in the dark requires a bit of fumbling around, but I was done easily within a minute. With practice it should take about half that time.
The tripod has almost no fine azimuth adjustment to speak of. The bolts fit into short slots (about a half inch in length) on the wedge base, so you can make small changes there, but it would be cumbersome to do it that way, and in practice you'll probably end up just picking the entire assembly up, rotating it, and setting it back down (gently!). I have a reader's submission for an alternate base to allow azimuth adjustments on the Tips section of my C5+ home page (see below). The wedge also has no fine altitude adjustments, but that is hardly the fault of the tripod.
I am happy to report that the tripod is rather sturdier than my workbench. Taps on that worthy damped out in about 2 to 3 seconds on terra firma; a similar tap damps out in 1 second or less with the tripod. Any additional stability would probably be overkill, as the single-arm "fork" mount of the C5+ only damps out taps in about 2 to 3 seconds as well. The tripod thus probably represents the optimal "elbow" of the combined scope/mount cost-stability curve. I should add that these stability measurements are not intended to be scientifically reliable and that they were done with all legs fully retracted.
I tried my old 15 mm Tele Vue Plossl on Jupiter, some 10 minutes after setting up. This is not enough time for the scope to cool down, but I find that I can still do some fun observing while waiting. The king of planets revealed some slow seeing turbulence—the kind that looks as if you're observing a planet under water. If that's all there is, the view will often hold up under higher magnification. As kind of a basis for comparison, I slipped in my 9 mm ortho (from Pocono, but same maker as the UO orthos). As expected, the ortho showed more detail, revealing four belts: NTB, NEB, SEB, and the equatorial band. Two sizable festoons striking out from the NEB were plainly visible, as were some striations in the equatorial band.
The ortho provides 139x and the 6 mm Radian gives 208x, but because of the wider apparent FOV of the Radian, the true field of view is nearly the same (the ortho is still a bit wider). I was impressed that the Radian lost not a whit of detail to the ortho; in fact, although little more could be seen, what could be seen was seen more clearly in the Radian. Using my barlow on either my Plossl or my ortho tends to blur the image. The seeing wasn't quite good enough to tell for sure, but there appeared to be a white oval nearly dead center on the meridian in the SEB (this was about 7:00 Pacific, or 0300 UTC 4 Jan). Color was somewhat more subdued than in the ortho, but better than in the Plossl, despite the greater magnification. The Radian is also shows no ghosting, unlike either the Plossl or the ortho.
The Radian also made short work of one of my Jovial activities—identifying the Galilean satellites. Through the Radian, all four showed obvious discs, with Ganymede and Callisto noticeably larger than Io and Europa, Callisto markedly darker than Ganymede, and Europa somewhat brighter than Io (although it was hard to tell with Io so close to the planet's disc). The discs are only partly due to the satellites's sizes, to be sure—the Airy disc is also a factor—but the differences in size and brightness were striking just the same.
Results on Saturn were similarly impressive. I had previously mentioned my efforts in seeing the delicate C or crepe ring, and noted that only in the ortho was it visible, and on a good night of seeing to boot. The Radian showed it also, possibly because the additional magnification darkened the sky background. It was not an easy sighting, but following it off the disc of the planet made it somewhat less difficult.
Many people have mentioned the "click-stop" adjustable eyecup on the Radians. I like it, but I found the stop a bit loose for my taste; I would have preferred it to stick more. Ed Ting has mentioned that he was able to see the full field of view even with the eyecup fully pulled out. I was unable to do so, even without my glasses (as I usually observe)—at full retraction, I was missing perhaps the outer 5 or 10 degrees of apparent FOV.
I know someone else on this group has pooh-poohed the 6 mm Radian in favor of the 8 mm Radian, maybe because the latter has one fewer element, but it's hard for me to say anything bad about the 6 mm Radian (and not just because it was a gift, OK?). It's a great eyepiece. I won't say it's making me rethink my strategy of buying only inexpensive and medium priced eyepieces, but just the same, I'm not turning it back in for a handful of orthos!
I later tried the Radian on the Trapezium, but by that time, the seeing had unfortunately deteriorated enough to make E and F simply invisible.
As an epilogue, I took advantage of my new digs to make another attempt at M1, the Crab Nebula. Some of you may recall that I made a concerted attempt to view the lone supernova remnant among the Messier objects in mag 4.0 skies, which just barely met with success (but success just the same). My new house has somewhat better skies—limiting mag about 4.5—so I decided to try again.
Again, my eyepiece of choice was the Vixen 8–24 mm zoom. I found it continually surprising—perhaps surprising isn't quite the right word—how long it takes for dark adaptation to return after viewing Jupiter and Saturn; after 10 or 20 minutes I was still seeing additional stars in the field of view. For those of you in suburban skies, M1 can be found between zeta Tauri and 114 Tauri—northwest of the former and almost directly east of the latter.
I found that M1 was easier to see here than in my previous house, which was not surprising. I also found that the optimal magnification to see it with the SkyGlow broadband filter was about 62x (20 mm), just as I had determined previously; without the filter, however, the optimal magnification was closer to 114x (11 mm), darkening the sky to about the same point as the filter did. The blur of M1 was easier to see with the filter, though, with which it was almost but not quite visible using direct vision.
It will be interesting to see if the same kind of correlation will apply to the other Messier objects I have left unseen thus far, which are almost all galaxies. All the same, I'm still looking forward to those times when I can take Opus out to a real dark sky.
9:00 p.m. 9 January 2000 PST (0500 10 January 2000 UTC)
I've previously mentioned my friend Allan, who owns a 10-inch LX200. (See my October observing report, which was only recently written up.) 'Round about the beginning of the year, after we'd moved in somewhat, he expressed an interest in going out again, on this particular Saturday, with a one or two-day-old moon due to sink fast on the heels of the sun. I'd been overwhelmed with the amount of cleaning we'd had to do around the new house, and this would make a nice break, so I agreed to go out.
We set out with a friend of Allan's, an older man named Joe, at about 7:00 that night, expecting to arrive at our site around 8:00. But I watched as Allan drove right by our previous exit (Templin Highway) and continued on.
"You didn't want that exit?"
"There's another one further on, with a less obstructed western horizon."
We got off 10 minutes later, at an exit whose name I don't quite recall. Allan does a lot of this by feel, which I'll admit at this time of night is the only way to do it, since none of the streets are lighted, except by the headlights of the cars on the Interstate. Eventually, we arrived at a locked gate preventing our further ingress, with those headlights still quite in full view.
We got out of the van and assessed our situation. The light pollution was minimal, but the glare of the headlights was a definite liability. Also bands of high altitude clouds were only slowly creeping their way eastward. In the dark it was difficult to tell at first that that was what kept us from seeing the northern sky—even Cassiopeia was hard to make out.
Eventually we decided to go back to our first observing spot, in a gentle valley off of Templin Highway. It was already a quarter to nine by the time we arrived, and of course it took some time to set up and begin the actual observing. Opus, my C5+, is a bunch faster to set up than the big iron, and I gathered that Joe was a beginner at observing, so I trained the scope at some (to me) familiar objects. We looked at the Andromeda trio—M31/M32/M110—as well as the Double Cluster. Both were fairly easy to see by the unaided eye, but of course much more vivid through even a 5-inch scope.
More galaxies. The last time we came out here, I'd wanted to see the Crab as well as M81/M82, but they were rising just as we had to pack up to go home for other reasons. This time there was no such pressure. The Crab (M1) was nice and high as we began, so we looked there first. After all the effort I've spent in finally seeing this object from my mediocre home skies, it was almost depressing how easily this object flashed into view, first at 25x and then at 53x. The S-shape so well- known to observers with small scopes (actually, it's a Z-shape through scopes with a reverse-image diagonal) could be made out within 10 seconds of seeing it. Then a secondary wisp of light, extending out of the top (north) face of the Z, appeared within another minute or so. Probably I was just deluding myself, but I thought I could make out the beginnings of some mottling within the Crab, as if it weren't just a featureless, diffuse nebula after all.
By this time, the pointer stars of the Big Dipper was just rising above the high eastern horizon (I mentioned we were in a short valley). Using my computer's star atlas, I was able to find my way over to M81 and M82. At 25x, this pairing is indeed a nice view. M81 itself is nothing to write home about, but M82 alone is worth the price of admission: a sinewy pencil of light, but one that appears as if it has been gnawed at a few times, during idle moments in class. Higher magnification (86x) showed these nibbles more easily, but with no real additional detail.
The LX200, which had been set up in the meantime, describes the deep sky objects at which it is pointed using short abbreviations that seem cryptic until you get used to them. Joe wanted to know what PN was. Planetary Nebula, and Allan and I explained what those are. Was one of the Messier PNs available? M27 and M57 were both down the sky along with the sun, but I seemed to recall…
M97, the Owl Nebula, was indeed up, and just poking out behind M81 and M82. Back to the computer atlas. The LX200 strangely showed its magnitude as 12; I have it at magnitude 9.9, which seems much more in line with Messier objects. It might be even brighter than that: Opus showed it easily, and with the UltraBlock in place it was in stark contrast to the black sky behind it. With averted vision, it was a reasonable matter to make out the subtle dimming that marks the "eyes" of the Owl. Over at the LX200, Allan was similarly convinced that the handset's magnitude value was in error. Its view, sans filter, was similar to that in the C5+ with the filter in place, but substantially sharper. When I lent my filter over there, the change in appearance was dramatic. One almost got the impression that we could look up from the scope and see this object with the unaided eye. Unfortunately, I didn't even think to try it with the UltraBlock blinking over my eye.
Back over to Orion, and M78, which I also had never seen before. It is a bit northeast of Alnitak, aka zeta Orionis—about as far away as Mintaka (delta Orionis), the rightmost star in the belt, but right angled away to the north. In my scope, it looks a little like a miniature version of M42, with a bright head and streaming tail, and one can easily imagine how Messier and his hunting buddies might have mistaken this for a comet at first glance. Just visible, almost hidden within the nebulosity, is one, or perhaps two, stars, which I imagine is the source of the light of M78.
We spent the rest of the night looking through the LX200, chasing mostly objects I'd already seen before, but was eager to see again through much bigger glass. That's part of having someone new join you in an observing session, I suppose, but happily so. This hobby isn't always about seeing new stuff, but just watching and standing in awe of that magnificent sky. As we were packing up to go just before midnight, it occurred to me to put all this in some vaguely poetic way, when I got home:
The night begins to cast its spell across
The sky—and over us. The sunset red
Gives way to green, then blue, all colors bled
Within a star-strewn dome, a cyan sauce.
And time itself would tarry yet a while
As if to watch us as we try to stay
The earth—our pier—and its relentless sway
That spins the stars around a central style.
The moment's here: The sun has sunk below
Eighteen degrees of visibility,
And still our eyes do widen at the glow—
Four thousand points of rare tranquility.
Amidst this purple sea we ride astern
Our lens-borne ships to wonder and to learn.
6:30 p.m. 27 January 2000 PST 0230 28 January 2000 UTC
Part of the benefit of observing with a small scope in a relatively warm climate such as we have in southern California is the quick cooldown. In contrast to other parts of the country where even with locally optimal conditions, you may have to wait as long as a half-hour just to get acceptable images, I can get them with my 5-inch SCT essentially "out of the box," i.e., my house.
When I returned home from work this evening, it was about 60 degrees outside and perhaps 65 degrees inside the house. There are, as a result, very few thermals to speak of, and the limiting factor becomes the quality of the atmosphere. Tonight, it was very good (7–8 out of 10, and what I now call M0.3F0.5.). I could tell it would be a good night when the 15 mm Plossl showed an absolutely rock steady image. I replaced it with the 6 mm Radian (208x), and touched up the collimation. I have previously remarked how the collimation will hold better if the collimation screws aren't too loose. It turns out that there is a problem if they're too tight, too—this causes an optical defect similar to pinched optics. So you should strike a careful balance.
My targets were Jupiter and Saturn, of course, and the Trapezium. Jupiter showed the NEB, the SEB, the NTB, and the EB fairly easily; the EB in particular was full of activity. Two festoons led from the bottom edge of the NEB, slanting celestial northwest to southeast (north to south, leading to trailing, as expected). They were about 60 degrees of Jovian longitude apart, and were centered around the meridian, one on either side, at about 7:00 p.m. local time. I don't keep up with Jovian longitude estimates, but based on the current longitude estimate for the GRS (not out during the time I was observing), I estimate the longitude at 7:00 to be about 300 degrees. The NNTB was also faintly visible and there was also some vague activity detectable south of the SEB, but it appeared merely as a dark and extensive polar cap.
Saturn again revealed the Radian to be a marvelous planetary eyepiece. At 208x the Cassini was a rich deep ribbon of dark grey (for it is narrower than the Airy disc of a 5-inch scope, and cannot truly appear black, even against the sky), and the C or crepe ring was faintly visible at the extremity of the ansae. Too close to the planet's disc and it was presumably drowned out in the glare. The planet's disc showed significantly uneven mottling throughout the southern hemisphere.
Both planets showed a gentle shading on the trailing limb, characteristic of a planet just past opposition.
I went to the Trapezium looking for E and F again. Even in very good seeing, I found again that their visibility is improved at only moderate powers—about 83x in the case of 5-inch Opus. At this power, E was consistently visible, but F was very difficult; I only saw it for about a half a minute, and averted vision was required. Other than that, it was invisible, even though E was intermittently simple to detect, even with direct vision. These two stars are a strange lot!
6:45 p.m. 28 January 2000 PST 0245 29 January 2000 UTC
Just a quick peek tonight; the seeing had been good enough to see the GRS last night, but it wasn't out while I was observing. Tonight it would be out at a better time, crossing the central meridian of Jupiter at about 6:30 local time. I set it up at about 6:20, but for various reasons I couldn't get out until about 6:45, at which time predictions suggested it would be about 10 or so degrees past the central meridian. Ten degrees doesn't sound like much, but it is already almost 1/5 of the way to the edge of the disc from the center. Features move fast near the central meridian; that's part of what allows accurate longitude measurements.
The 25 intervening minutes allowed Opus to cool down, and by the time I went out, a 15 mm Plossl showed an absolutely rock steady image. That's somewhat misleading, since that eyepiece only yields about 83x, so I replaced it again with my prize 6 mm Radian. Through that eyepiece, the image shimmered ever so little at the edge, but it was visible. The seeing was comparable, perhaps just a little worse (7 out of 10, or now I call it M0.5F0.5.). Similar details were visible, but a tad hazier.
With regard to my quarry, the GRS hollow was plainly evident, and a few seconds of patient staring yielded the pale salmon colored GRS as well. I don't think I could see the whole thing; there was a redder core that was detectable a good distance from the edge of the hollow. I also looked for ovals in the SEB, but couldn't see them. I could see what appeared to be a streaking white division in the SEB, but couldn't be sure.
Later, when I came in and looked at recent astrophotos of Jupiter, it was revealed that the ovals are actually most common in the STB, which is not quite clear enough through Opus to see detail in. But I had seen a real feature in the SEB—the streaking white division was really a streak of three or four stretched out ovals being sucked into the vortice of the GRS (or at least, that's the way it looked to me). So that was a nice little surprise.
8:00 p.m. 1 February 2000 PST 0400 2 February 2000 UTC
It started out as just a little looksee for the two gas giants. It ended up being a bit longer than that, as many observing sessions do. I set up at about 7:30 p.m., allowing the scope to cool down. A quick peek at about 15 minutes revealed that the seeing was not quite up to the last couple of sessions; I rated it as average to good (5 to 6 out of 10, or now I give it M1F1.). I suspected it probably wouldn't be a great night to observe the planets, but you never know.
Another 15 minutes didn't improve the situation materially. Saturn looked better from an aesthetics point of view. The Cassini division was simple to see, but it was pretty hazy though. Jupiter, perhaps because it was brighter, didn't show much beyond its two main equatorial belts. There were occasionally hints of the NTB, but it was hard to tell for sure. Unlike before, when the leading (celestial western) limb of the disk was sharp, I couldn't ever get it to settle down tonight.
Accordingly, I didn't hold much hope when I turned Opus toward the Trapezium. But E was fairly steadily visible, and even F was there from time to time. But it took quite a bit of patience to see, and I know I couldn't possibly find it unless I knew precisely where it was.
A tactic I use quite a bit in trying to detect E and F is averted vision; it's not just for dim fuzzies. I've recently suspected that my averted vision is more effective in some directions than in others; that is, I have a better chance of detecting an object by looking off in the 1:30 direction (45 degrees clockwise from straight up) than in any other direction. I urge any readers to determine which direction their averted vision works better, because it makes sense to me that it won't be exactly the same in all directions.
I also find, for whatever reason, that I have a much better chance of detecting E and F through my 15 mm Plossl (83x) than with any other eyepiece. I'm not sure exactly why that is.
After staring at blank spots looking for E and F, I suddenly realized that my vision had dark adapted sufficiently for M42 to look rather stunning, and I decided to take advantage of that by heading toward M1. I'm discovering that as I spend more time hunting this down, I'm getting better at seeing it in the moderate light pollution around my home. Yet another reason to keep plugging away at the same objects.
Now thus far, I hadn't seen any new objects. But at this point I decided to take a hint from the March 2000 issue of Sky and Telescope and hunt down M46 and M47. This pair of open clusters is almost directly due east of Canis Major's head. The problem is, that head is only barely visible by the unaided eye at its current elevation. (It will be getting higher later this year, or at later times at night.) So I noted that they were also just outside a triangle made up of Sirius, Procyon, and Betelgeuse. A little jiggling back and forth revealed a bright set of stars, which I guessed to be M47.
A look through the eyepiece (32 mm Plossl for 39x) showed that the stars weren't part of M47 itself, but were very close to it. M47 is a bright but spotty cluster; aside from the smattering of bright stars, there don't appear to be hardly any background members—if there are any, they are indistinguishable from the general background.
M46 is a different story. It lies a couple of degrees to the east, and a little to the south. At first, one sees only a few bright stars, like M47, but dimmer. Then gradually, almost like magic, a fuzz of dimmer stars—many 9th and 10th and 11th magnitude—glows into view. It takes a bit longer to appreciate M46 than M47, but the time spent is amply rewarded with one of the richer open clusters in the night sky. One can easily understand why Charles Messier put this in his catalogue of comet impostors.
Sue French's article in Sky and Telescope also discusses a planetary at the northern limb of M46, NGC 2438, which I have listed as about mag 10.1. I knew I would have little chance to see it without aid in mag 4.2 skies (at M46's altitude), so I brought out my UltraBlock, a narrowband filter. Several authors have written about using the filter not screwed in to the back of the eyepiece as usually intended, but slid back and forth between the eye and the eyepiece, "blinking" the nebulae into view.
Doing it this way, I did get the impression that there was something there, but it was a very vague sensation. There are two relatively bright stars at the northeast limb of the cluster; the dim fuzz seemed to be in a line with these two stars, toward the "top" (north) of the cluster and about half again as far from the northernmore of the two stars. I think the problem is that blinking works well from dark sky sites, where the ambient light isn't enough to distract you. But from suburban sites, where local light pollution can ruin your night adaptation, I really need to push my eye up against the eyeguard as much as possible. So I got the impression of NGC 2438 from blinking, but to confirm it, I needed to screw it in as usual.
When I did, most of the stars vanished, of course. The two brighter stars were still dimly visible, and averted vision showed something, but every time I tried to look back to determine where I had seen the fuzz, I lost track of where it was. After some 15 to 20 times going back and forth, I finally decided on the location, which I later verified with my computer atlas. Very interesting, and a definite object to return to when I get to a dark site. Incidentally, Sue's article notes that 75x is necessary to distinguish NGC 2438 as non-stellar. However, I didn't do that, really, except that here was a "star" that showed considerably better through the UltraBlock than not!
Another two Messier objects knocked off—I'm almost halfway there!
8:00 p.m. 5 February 2000 PST 0400 6 February 2000 UTC
Ordinarily, the new moon is the best time to observe deep-sky objects, since the moon's bright light isn't around to drown everything else out. Unfortunately, Los Angeles has seen a bit of rain lately—just a bit—and as I began looking up tonight, that moisture was suspended in a mist overhead. And although moonlight wasn't a problem, the lights of Los Angeles were, and those were exacerbated by the mist which reflected a lot of that light down in my direction.
Nonetheless, some deep-sky observing can be done under these circumstances. It takes some perseverence and some novel star-hopping techniques to find the objects, and then you have to trust you've actually found the things you're looking for.
My targets were objects that are ordinarily trivial to find by any techniques—even on an average night from my home, where the limiting magnitude is typically in the mag 4.0 (near horizon) to 4.5 (zenith) range. Two of them are open clusters found in Sue French's article in the March 2000 issue of Sky and Telescope: M48 and M50. The third is another open cluster, south of these two and making roughly an equilateral triangle with them—M93.
M50 was first. As shown by the photo accompanying Gary Seronik's binocular observing article on the fold-out map, M50 is just inside a triangle formed by Sirius, Procyon, and Betelgeuse. It lies about 3/8 of the way from Sirius to Procyon. Using my finderscope as a reflex finder—that is, like a Telrad—I pointed the scope at roughly the right position and looked in my 32 mm Plossl (39x). Sure enough, there it was, a little off center in the eyepiece, but that was easily fixed. As bright as the sky was, Sue's "housefly" was not quite evident to me, but there were two nice arcs of stars that I imagined could be part of some kind of housefly pattern.
M48 came next and was a bit harder to find. Alpha Monocerotis, a magnitude 3.9 star, was only visible through the finder as an unassuming point of light, and from there I tried to make my way up to zeta (magnitude 4.4), about 8 or 9 degrees to the northeast. No such luck. Instead, I noticed on my map that zeta made a rather elongated right triangle with Procyon and Sirius, with zeta at the right angle, closer to Procyon. Then, as Sue indicates, there is C Hydrae about 5 degrees to the east, and M48 is south of zeta Monocerotis and C Hydrae, in a broad triangle. Through the eyepiece, under these skies, M48 looks like a loose scattering of stars; my impression is that of a poorly-defined figure standing in the doorway of a makeshift house.
I mentioned that alpha Monocerotis at magnitude 3.9 was a rather dim light through the finder. With the unaided eye, it was invisible, but I suspect only barely so. That would make the limiting magnitude at that altitude about magnitude 3.8. But M93 is significantly further south, and at that location, the limiting magnitude was only about 3.3.
My path toward M93 began with delta Canis Majoris, the base of the Great Dog's tail (this is a family report). Opus's equatorial mount made it straightforward to move more or less directly east toward kappa Puppis, magnitude 3.3, which as you might guess was barely visible by the unaided eye. I then found xi Puppis a couple of degrees to the northeast. M93 is then in a 30-60-90 right triangle with these two stars, with xi being the right angle and kappa being the 30 degree angle. (As you can tell, I make frequent use of right triangles in my star-hopping.) I looked through the eyepiece and could make out nothing. At first I thought I saw something fuzzy, sort of like an open cluster, but further examination revealed only a pair of stars of eighth and ninth magnitude. I went back and forth between my atlas and the finder, and gradually became convinced I was looking in the right place, but still all I could see was that pair of stars.
Well, I thought, perhaps I should just stop messing around and stare at that spot for a while. That paid off; after a minute or two, I could make out by averted vision a dim fuzz on the other side of the eighth-magnitude star from the ninth-magnitude star. I couldn't be sure, but it sure looked as if it could be the "missing" cluster. The fuzz seemed to be slightly elongated, in a direction perpendicular to the line formed by the two stars and the fuzz.
A visit to my star mapping program confirmed my guess. The "double star" was indeed a marker to M93. I think the stars are HIP 37729 and HIP 37738, which are both about 200 parsecs away (with a plus or minus of about 20 percent?). Stephen O'Meara gives the distance to M93 as about 1,100 parsecs in his Messier Objects, so the stars are likely foreground objects and not truly part of the cluster.
From an aesthetics point of view, it was a bummer evening as far as deep sky objects. (I also tried observing Saturn and Jupiter, but the seeing was fast and only average, so I gave that up too. Under my new seeing rating, I would call it M1.5Fi.) But the thrill of the chase is something worth its own while, and I suppose I can't complain too much about the weather; as I packed up about an hour or so later, the temperature outside was in the low 50s.
8:00 p.m. 5 February 2000 PST 0400 6 February 2000 UTC
With a couple of hours free time this afternoon, I decided to attempt a daytime observation of Mercury. Venus was also up, but descending toward the horizon, so I didn't go there. My ephemeris indicated that Mercury was almost precisely 15 degrees east (about one hour of RA) and some 4.3 degrees north of the sun. Armed with my Thousand Oaks glass solar filter, I first got the sun in my sights.
That wasn't so hard. Despite warnings to the contrary, I find no harm in leaving the C5+'s rather small 6x30 finder open while locating the sun. (After all, far larger telescopes are OK for projection.) Just being careful not to actually look through the finder itself, I stood off to one side and used the shadow of the finder to roughly align the scope toward the sun. At that point, the projected image of the sun became visible on the ground. I adjusted the scope further until that image was superimposed on the shadow of the finder. At that point, the sun was squarely in the field of view of the main eyepiece (solar filter already in place), and I capped the front end of the finder.
I paced off 15 degrees to the east and 4 degrees north with my 32 mm Plossl (39x) and found absolutely nothing. With its 1 degree field of view, it should have covered Mercury just fine, but for whatever reason, I simply couldn't find it. I repeated all the same steps with my 15 mm Plossl (83x)—still nothing. I even tried it with the 25 mm SMA that came with Opus, for 50x—nothing again!
At this time, I reasoned that I simply didn't have enough magnification. The 6 mm Radian, with its superior contrast, should do just fine, but its field of view would probably be too small. So I interposed the f/6.3 focal reducer/corrector and then put on the Radian, for about 130x.
This time, success! But, of course, Mercury was exceptionally small and dim against the bright blue sky. I could see the slightly gibbous disc, which seemed to cover about 70 percent, but which according to the February 2000 issue of Sky and Telescope should be somewhat larger by interpolation. No surface details were visible, at least not within a few minutes or so. I should have been a bit more patient.
Instead, I tried repeating my exact steps without the reducer. Alas, I could not relocate the small planet. I searched, exasperated, for over a half an hour, but couldn't find it again. I probably should have left the scope in place and simply removed the reducer, but I was afraid I wouldn't be able to find the focus again. I'll try it that way the next time and see if I have better luck.
Conditions: The sky was cloudless, and it was daytime, so transparency wasn't really an issue. The seeing was M1F1, which I would previously called about a 5 or 6 out of 10.
Copyright (c) 2000 Brian Tung