9:30 p.m. 3 Sep 2000 PDT (0430 4 Sep 2000 UTC)
I went out to whittle down the remaining items on my Messier tour (now entering its third year). It was a somewhat misty night, with a limiting magnitude down to about 4.5, which was made somewhat more difficult to negotiate with a scattering of high cirrus clouds. A little patience was all that was needed for those, though.
All these observations were of course made with Opus, my 5-inch SCT, fitted with an f/6.3 focal reducer/corrector and using exclusively (for convenience more than anything else) my Vixen 8–24 mm zoom.
I started my night out on M2, which can be found at roughly the same declination as alpha Aquarii and the same RA as beta Aquarii. This globular is very bright and takes magnification well; I saw it best at 98x and probably could have gone higher if I had taken the time to take out the R/C or use the Radian instead. But I'm "saving" the Radian for the planets. M2 appeared almost triangular at low powers, and at high powers, this appearance resolved somewhat into three arcs—two bright ones to the northeast and south-southeast, and another weak one looping northwest to west. There seemed to be a dark streak apparent on the east side, slicing north to south, but I couldn't be sure. The globular also condensed a little southwest of center, to my eye.
In contrast, M72 was basically detail-free in my scope. It is found near the Saturn Nebula, near two 6th-magnitude stars; again, it's at the same RA as one and the same declination as the other. It required high power (best seen at about 60x) just to see at all, and all I could see was a hazy patch. This represents another threshold observation.
Nearby M73 is one of Messier's "mistakes," a quartet of 10th-magnitude stars that appeared to Messier to exhibit some nebulosity. There isn't any, as it turns out. One of the mini-projects with the Hipparcos data was to determine if these stars might be at least at the same distance and form a kind of open cluster. However, the result was inconclusive. M73 is about 1.5 degrees east of M72, at about the same declination. It's possible, through a small scope, to see how Messier might have perceived nebulosity; otherwise, it's an uninteresting little grouping.
My next target, M30, is a nearby globular at the third corner of an equilateral triangle with epsilon and zeta Capricorni. It's fairly bright, though not as bright as M2, and seemingly very strongly condensed at its center, which is about as bright as a nearby 9th-magnitude star. At 71x, I could make out some thin trails leading northwest, southwest, and one that led vaguely southeast or east.
M29 is one of those objects that I haven't seen for no good reason, except that it's not a particularly showcase object. It's just about a degree and a half south of gamma Cygni. Best seen at about 71x, it featured about 9 bright stars, four of which made a kind of interesting mini-Great Square. "Behind" these 9 stars were an array of a couple of dozen stars, presumably cluster members, just at the edge of visibility.
M52 is a more interesting open cluster, easily found by extending a line from alpha Cassiopeiae through beta, and continuing along about 1.2 times as far again. It's nestled up against a 7th-magnitude star, and is a faint haze of fairly uniformly dim stars, almost like a miniature version of M46. About a dozen stars were visible with averted vision, although I got the sensation of more illumination there than I could resolve. Best seen at about 49x.
My last cluster of the night was M103, found about one-fifth of the way from delta to epsilon Cassiopeiae. It too is close to a 7th-magnitude star, and if possible is even less conspicuous than M29, with only about four or five brighter stars, although an additional 20 or so stars were just barely visible once I pumped the power up to about 65x.
Finally, I trained Opus on M76, the last of the four planetary nebulae I've spotted from Messier's catalogue. The Little Dumbbell, as it's often called, is about halfway between gamma Andromedae and delta Cassiopeiae, just a bit north of phi Persei. I first tried seeing it without a filter, with no luck. What a dramatic difference when I slid my Orion UltraBlock (a narrowband filter) at the end of the zoom! It was dimly but easily visible at a wide range of powers, and took magnification well all the way to the top, at 98x. I still couldn't make out much detail, other than the fact that it's aligned roughly northeast-southwest, but this is most obviously not a 12th-magnitude object, as it's sometimes described; I'd estimate it at around 9.5 or so, although that might be a bit optimistic.
8:00 p.m. 5 September 2000 PDT (0300 6 September 2000 UTC)
Tonight saw me striking another six Messier objects off my list, reducing the remaining Messier "prey" to just 12 objects. I was most concerned about M19 and M62, since they are beginning to fall into the twilight. They were very close to the moon tonight, so I wasn't sure how well they would show up, but they turned out not to be the toughest objects I had to see.
M19 is east of Antares, about as far away from it as pi Scorpii is, but on the other side. It is not too bright, but that might have just been light pollution from the moon. It appeared to me to be elongated somewhat along a north-northwest to south-southeast axis, with the northern half slightly more bulbous than the southern. I sensed incipient resolution under these conditions, with the best view at 78x, but probably true resolution would have to wait until I get under dark skies.
M62 is just 4 degrees south of M19; dead reckoning from M19 alone was sufficient to get me there. It's one of the advantages of using an equatorial mount. M62 was also best seen at 78x, and it was quite evidently brighter than M19, although again, its greater distance from the moon on this evening might have been a factor. I was able to make out two separate details: one, a thin bright horizontal row of stars that seemed almost to bisect the globular; and two, a little hook rising up from the horizontal bar. The effect was almost like a hazy Coathanger cluster.
I tried for some time to find M23 by star-hopping, without success. I found it instead from M19 and M62, again by dead reckoning. It is a rich open cluster, with about 40 stars easily visible. Surprisingly, I wasn't able to make out many more stars by using averted vision or by changing magnifications; the best view was afforded me at a relatively low 49x.
M40 is another one of Messier's "weirdities," an unassuming binary of no particular merit. It can be found by running a line from gamma Ursae Majoris through delta, and then about 1/4 as far again. I saw the primary of the pair as the western one (the binary is roughly on an east-west line), by about 0.2 magnitudes, perhaps. I didn't make any kind of rigorous measure of the separation, but would estimate it as roughly one arcminute.
M101, not the globulars, was the toughest object of the night. I eventually used a starhop using theta and kappa Ursae Majoris; those two are on an east-west line and can be used as a baseline to jump up to M101. (Alternatively, it makes a roughly equilateral triangle with zeta and eta Ursae Majoris.) I could just barely see it at 32x; any greater power tended rather to obscure this large galaxy than reveal it. It was another one of those threshold observations, with no detail, just a large round blur.
M26 was my last object; it is near M11, the Wild Duck cluster. I found that worthy first, and then did a small star-hop using the dim stars of Scutum. Run a line from alpha Scuti through delta, and then about 0.4 times again as far, and there you are. The open cluster is small—smaller than I expected—and marked by a 7th-magnitude star that lies on the cluster's western edge. In the mirror-reversed view that Opus provides with the star diagonal, the cluster seemed to form a kind of italic J, with the bright star at the bottom point, and the long stalk running up to the north-northeast.
Here, just in case anyone is wondering, is a list of the remaining 12 victims:
+ M054 RA 283.764, Dec –30.477 mag 7.6 + M055 RA 294.999, Dec –30.962 mag 6.3 + M075 RA 301.521, Dec –21.921 mag 8.5 * M034 RA 40.504, Dec +42.786 mag 5.5 + M079 RA 81.045, Dec –24.524 mag 7.7 * M037 RA 88.075, Dec +32.550 mag 6.2 * M067 RA 132.870, Dec +11.826 mag 6.1 § M106 RA 184.742, Dec +47.308 mag 8.4 § M064 RA 194.182, Dec +21.683 mag 8.5 + M053 RA 198.229, Dec +18.169 mag 7.6 § M083 RA 204.250, Dec –29.867 mag 7.6 § M102 RA 226.626, Dec +55.764 mag 9.9
Five globulars, three open clusters, and four galaxies: a roughly even mix. There are some obviously easy ones—M34 and M37 come to mind—that I haven't gotten to for no particular reason.
9:00 p.m. 10 September 2000 PDT (0400 11 September 2000 UTC)
I spent a half-hour this evening whittling away another two objects from my Messier observation list, leaving just an even 10. My first target was M54, a globular a bit off the handle of Sagittarius's teapot. It's remarkably condensed; it looks almost starlike at low powers. I had to set the Vixen 8–24 mm zoom to 12 mm (65x) before I could really see the halo of the globular to good effect. It showed a prominent jet to the southeast, as well as a minor headcap of stars on the northern end.
My second target was M55, another globular, but one much harder to see than M54. I found no good way to search for it other than a laborious star-hop through the eyepiece. In this regard a highly detailed atlas or a planetarium program that goes at least down to magnitude 11 or so is greatly useful. My quarry, unfortunately, did not reward the effort spent in finding it—it was barely visible as a wide blur with no visible condensation. I could make out no detail in it.
I also tried to find the "alternate" M102 (NGC 5866) in Draco. I've read enough material on this galaxy and its possible connection with the Messier list to form a weak opinion that this was really the galaxy intended to be included with the list. The whole thing resembles the Shakespeare debate (orthodox Stratfordians vs the renegade Oxfordians). In any case, the moon was too bright, even on the opposite side of the sky, for me to make it out.
9:00 p.m. 17 September 2000 PDT (0400 11 September 2000 UTC)
With the moon safely new and set, I took advantage of what I figured would be one of my last opportunities to find the aforementioned M102. It was considerably darker than last time, with the limiting magnitude about 4.6 by my eyes. With the appearance of Jupiter and Saturn just before midnight in recent days, I've taken off the f/6.3 focal reducer/corrector, so the Vixen zoom now yields higher powers (but a narrower true field of view).
This time, I was successful in tracking down and seeing M102. I found it about 1.2 degrees north of a fifth-magnitude star, which does not appear to have a Flamsteed number. (Curiously, Flamsteed himself never used the numbers associated with him. He used Bayer letters, though.) This M102 (NGC 5866) is within a few arcminutes of one corner of a "kite" of four ninth-magnitude stars. It is a faintly seen sliver of light running roughly northwest-to-southeast. I noted a little condensation toward the center, but the principal feature that could be seen was that it was strongly elongated.
I was also able to capture M75, which I have previously—for some weird reason—labelled in my notes as an open cluster. It is actually a globular, which I found using a star-hop using alpha, beta, then rho Capricorni. It is very near a 10th or 11th-magnitude field star, which is much dimmer than M75 in integrated magnitude, and somewhat more difficult to see through the eyepiece. M75 is a small globular, very condensed, with an almost stellar center, not unlike M54. It really did seem to be surrounded by a halo of light, almost like a planetary nebula. That halo seemed somewhat brighter toward the north-northwest, and I also made out a horizontal—I should say east-west—arm sticking out from M75 to the east.
One hundred two down, eight to go.
9:30 p.m. 28 September 2000 PDT (0430 29 September 2000 UTC)
As many of you know, I observe primarily with Opus, my 5-inch SCT, but recently I purchased a used Tele Vue Ranger, which I reviewed separately here about a week ago. (This review has since been posted on the Cloudy Nights web site, which see.) Some of you wrote to say that you were interested in a comparison review. I was interested myself, so last night, I pulled out the two small scopes for the first part of a planned two-part faceoff. The second part will be under dark skies, and will take place either this weekend or the end of next month.
It was kind of exciting setting up Opus and the Wocket (that's the name I've given to the Ranger); one scope is well and good, but with two of them together, it almost has a party feel to it. As I was planning to observe a number of targets across the sky, it was impossible to set them up in such a way that I would never have to get up out of my seat, but the Ranger/tripod combination is so light that it really doesn't matter. Still, I managed to contain my observations to two main areas in the sky.
First up, rising in the east, was NGC 869/884, the Double Cluster. The pair are actually in Perseus, but I find it much easier to starhop there from delta and epsilon Cassiopeiae. Under dark skies, of course, the two are naked-eye sights, but finders are required to locate them in light-polluted Santa Monica. (There was an unusual amount of humidity this night, lowering the zenith limiting magnitude to 4.3, about a quarter-magnitude worse than usual.) Opus has the 6x30 finder that I've taken the stop out of, and a week after making off with the Wocket I purchased a Tele Vue Star Pointer, a red-dot finder.
It was a snap to find the two clusters in both scopes. The Wocket is a 480 mm f/6.8 scope, so with the 15 mm Plossl in, I got 32x. Opus had the f/6.3 focal reducer/corrector plus the Vixen 8–24 mm zoom set on low-power, also for about 32x. At identical powers, I was somewhat surprised to see that the Ranger showed more pinpointy stars, although they were brighter and more numerous in the C5+. Despite the slight fuzziness with Opus (which was time-varying, so some of it—possibly most of it—was seeing), the clusters were an easier view than in the Ranger.
I had similar thoughts, only more so, about M34, an open cluster which for some reason or another I had never seen through Opus. (I have seen it in binoculars.) M34 is a very scattered cluster, which gives me the same feeling as fractal designs: it's got a handful of very bright stars, with lots of space, then as you get closer in, you see clumps of dimmer stars with lots of space, then you get closer in still, etc. I could go about one level "closer in" with Opus than with the Wocket, although the view was more aesthetically pleasing in the latter. I keep thinking this is a pretty good scope to introduce someone to astronomy.
Next, I moved to the high western sky to take a look at the two bright planetary nebulae: M57, the Ring Nebula, and M27, the Dumbbell Nebula. Here, the Wocket began to lag a bit further behind, with its shorter focal length, smaller aperture, and attendant lower maximum power. M57 is well-known as among the best planetary nebulae for small scopes even under bright skies, but with the Ranger I ran into a problem—I couldn't magnify it enough to see it as well as I wanted to. With or without the UltraBlock (Orion's narrowband filter), the best I could get was a sort of "red blood corpuscle" appearance (80x with the 6 mm Radian, so like a red blood cell at a distance of half a millimeter!).
Opus, on the other hand, took all the magnification it could get, and the center dimming was more distinct at higher power. So was the ever so slightly elongated contour of the Ring, which was only hinted at in the Ranger.
M27 is supposed to be more heavily impacted by light pollution than M57, but with the UltraBlock, it was a more interesting sight than the Ring, in either scope. It looked like a glowing bowtie through the Wocket, with some hints of structure that stubbornly refused to stay put in my view. It was considerably brighter in Opus, and at higher power, the faint tendrils off the ends of the dumbbell that stretch into the secondary "American football" shape could be seen. (So I have become better at this—it's not all a complete waste of time!) I wonder why some see no improvement in the view with the UltraBlock. To me, the difference it makes in M27 is practically night and day.
There was a recent thread on sci.astro.amateur about resolving delta Cygni, the western one of the bright wing stars (closer to Vega), so I trained both scopes in that direction. This is a relatively tight binary for the magnitude difference: the secondary is 2.2 arcseconds away and about 3.5 to 4 magnitudes dimmer. As is my usual practice in this regard, I intentionally didn't look up the position angle prior to viewing the pair.
It was tight but definite in the C5+. The magnitude difference seemed greater than 3.5 to 4; this pair was not very difficult (I find E and F in the Trapezium more difficult), but it was certainly less obvious than, say, Rigel B, which has a greater difference but a larger separation. I estimated the position angle (just eyeballing it) at about 240 degrees; does anyone know an accurate current value?
It was not at all certain in the Ranger, as you might expect. The seeing was just variable enough for me to occasionally glimpse what might be the secondary, but I couldn't be sure. In the end I had to regard it as a suspected but unconfirmed observation. I might have been able to see it if I could have gotten more magnification, but 80x was as high as I could go.
In the same general area, of course, is epsilon Lyrae, the Double Double. With pairs of approximately equal magnitude, both doubles are easier than delta Cygni, and I could split it in the Ranger at 80x as well as Opus at 83x. However, the quality of the split made the difference between the two scopes quite distinct. The Wocket showed each pair as two balls—the Airy discs—nearly touching, with an almost indetectable halo around each ball. Opus, on the other hand, showed each pair as two balls with a dark space clearly separating them by a wide margin, but each ball also had an obvious halo around it—the first diffraction ring. Again, I got a sense of the difference between detail and aesthetica value.
Next up was M31. Under these skies, the Ranger lost its one advantage over the C5+: its wide field of view. With the 32 mm Plossl in for a yawning 15x view, it was clear that the trio would have made an imposing sight—had they been clearly visible. As it was, the nucleus of M31 was well seen, as well as another broad swatch of light that is the surrounding center. M32 was dimly but easily seen, and might have been mistaken for a star at that power if I hadn't known where it was. M110 could be suspected but not confirmed.
The best Opus can do is about 24x, for a noticeably narrower true field of view. The increased light-gathering power was helpful, and I could barely make out some of the principal galactic disc of M31, running out most of the way to M32. M32, for its part, was noticeably less starlike at this power and aperture. I still couldn't be sure I was seeing M110, though.
The one object where the Ranger was the clear winner was the next one, M45, the Pleiades or Seven Sisters. I had seen it at 10x in my 10x50 binoculars, and at 24x in the C5+, but never in that gap in between. The Ranger fills it very nicely. You get the increased brightness that an extra 20 mm of aperture gives over the binoculars, but the relative darkness that surrounds it sets the cluster apart in a way that is just not possible with the 5-incher. The main cluster just about fills the view in the C5+, reducing its visual impact.
Last up were the two gas giants rising in the east as I was finishing up, over three hours later. As you might expect, Opus had the edge here as well. It took a while for the seeing to settle enough and for the planets to rise up out of the atmospheric muck, but in the end, power and aperture carried the day. (Or night, whatever.) Saturn was nice in the Ranger, showing the Cassini quite distinctly. I disagree with those who say it cannot be seen in a scope under 60 mm of aperture, by the way. I know it is there, but it is so dark that it is unmistakable when you see it and when you don't.
However, through Opus, Saturn is a revelation. The planet's globe shows color and detail unseen in the smaller refractor, but the rings are the true glory. The Cassini division was sharp and distinct all the way around, including directly in front of the planet. The crepe ring could be faintly seen, even in the light pollution, except for close to the planet where it ran into a sharp contrast effect (the crepe ring against the planet).
I also made an observation of the Encke minima—not the gap at 84 percent, but a wide albedo feature across about a third of the A ring. Since this has been a matter of some dispute on sci.astro.amateur, I thought I would say a few things about this. At 208x, it was, like the Cassini through the Ranger, unmistakable. I did notice, however, that the diffraction effects of the C5+ on the brighter parts of the A ring surrounding the minima made that minima seem narrower than it really is. It did not appear as a sharp line, but it did seem narrow. Could it be that people are confused by this effect into thinking that they have seen the Encke gap? I don't doubt observations of the gap in scopes as small as perhaps 9 to 10 inches, but I think this explains claims of the gap in small, 5-inch class scopes.
Finally, Jupiter, the daddy of them all. Again, a nice sight in the Wocket, with Io about to transit and its shadow already visible in the SEB. The NEB was quite a bit darker and showed some color and some lumpiness. The NTB could be faintly seen. But Opus blew it away, a bit to my surprise—I didn't expect the difference to be quite that large. Part of it must be the deeper power available. But one point that particularly caught my attention was the distinctness of Io's shadow. It was absolutely stark in Opus, not just visible as it was with the Ranger. In the refractor, the Galilean satellites were small spikes of light; in the 5-incher, they were globes, largely Airy discs, but also the relative sizes could be made out. The NTB was more distinct, and I saw a pair of smallish festoons trailing into the EB. I could just barely make out the GRS, trailing now out of sight, but the indentation that the storm makes on the SPZ was evident. The split in the SEB was also more obvious in the C5+.
So, the bottom line: The C5+ has, potentially, about 3 times the light gathering power. In practice, the difference is more like 2 to 1. In dark skies, that might have a larger effect, but under bright skies, all it really does is make the stars you can see easier to see with the larger aperture. The 5-inch SCT, however, also has an edge in the resolution and contrast arena. The unobstructed aperture of the Ranger makes up a little for its smaller primary, but in the end it's just too much to make up. As a result, I finished up my night by spending over an hour looking at the planets through Opus, while I packed the Wocket away for later use.
But let's not discount the Ranger entirely—it is much lighter than the C5+, mounted and ready to observe, by a factor of about 3 to 1. It was, as I've mentioned previously, almost a pleasant exercise to chase down sights across my backyard. And many objects look nicer in the Ranger than they do in the C5+, which may make a difference if you're thinking of it for family use. I plan to bring the Wocket out reasonably often for observing—just not as often as Opus, is all.
4:30 a.m. 1 October 2000 PDT (1130 1 October 2000 UTC)
With the remaining set of my Messier objects not up at ordinary viewing hours, I had to either wait for a few months for them to rise earlier, or get up early one morning to bag a few of them. I chose the latter, so I set the alarm for 4:30 a.m., with the scope mostly out and set-up-able in a matter of minutes.
I had less difficulty getting up out of bed than I thought I might, and got right to work. Unfortunately, there was still a lot of humidity, which was also unfortunately very well lit by L.A. and surroundings to the east and southeast. I estimated the limiting magnitude at about 4.2. My first object, M79, is a globular in Lepus and in prime position to be washed out by the sky brightness.
The easiest way for me to star-hop to M79 is by extending a line from alpha Leporis through beta, and then on to a fifth-magnitude star that is about equidistant from beta and epsilon. M79 is then less than a degree to its east-northeast. It was actually quite easily visible, partly because it is moderately condensed; I saw it best at 19 mm for 66x. It lies between two 9th-magnitude stars. Though it itself was not lost in the light pollution, nearly all of the detail was. The best I could make out was what appeared to be an arc trailing off to the west-northwest.
As I was in the area, I decided to take a peek at M42, the Great Orion Nebula, which I hadn't observed since the beginning of the year or so. Even in light pollution, it's still an awesome sight: easily seen by the unaided eye (or at least theta1,2 Orionis are), so finding it is a snap. And through the scope, it's still got more detail than practically all the other Messier objects put together. That's something of an exaggeration, but it comes close to capturing the grandeur of this object. Just the inner bright portion, the sigma-shaped bright nebula illuminated directly by theta1, is rife with dark streaks and ragged edges. The main four stars of the Trapezium were easily seen at any power, so I tried for E and F. I could see E fleetingly, best at 11 mm for 114x, but there was no sign of F.
Next up was another Messier object that I hadn't seen previously through Opus for no good reason (though I had seen it through binocs), M37. It is just outside the Auriga polygon on the east side, about two-thirds of a degree to the northeast of a sixth-magnitude field star. At 22 mm for 57x, I saw a football-shaped island of stars, elongated about west-northwest to east-southeast, relatively well set off from the surrouding darkness, for a nice visual effect. It is fairly rich; even in the light-polluted sky, I could count about 25 stars with direct vision and perhaps another 15 to 20 with averted vision.
Again, since I happened to be in the area, I decided to take a look at M35, an open cluster that Walter Scott Houston called his favorite open cluster. It is indeed another magnificent sight, found just off of eta and 1 Geminorum. I tried to find IC 2157, a visual companion cluster (though not physically related), but no dice—it was just too bright.
Last on my list for the morning was M67. Under ordinary circumstances, this is a relatively easy object to find with an equatorial mount, considering the dearth of bright stars in the area. Start from Procyon, and using an aligned mount, sweep eastward until you hit a pocket of six third and fourth-magnitude stars that is the head of Hydra. Then sweep northward until you are in the vicinity of alpha Cancri, a fourth-magnitude star (this is a dim constellation). M67 is then just about two degrees to the west.
However, under these bright skies, and for another reason that I'll explain later, I had an extreme amount of trouble just seeing it. Part of it is that M67 is a relatively uniform cluster and very large, so that although it's a sixth-magnitude object, that light is spread out over such a large area (about half a degree wide) that I could barely make it out at any power. In fact, I saw it best—barely at all—with the 32 mm Plossl for 39x. Only about two or three stars were visible with direct vision—maybe only a half dozen more with averted vision.
When I put away my Messier list and closed out the morning with Jupiter and Saturn, I found out why. I had been lazy and not put on my dew cap, and the corrector plate was entirely dewed over. It was such a shame—I should have observed the planets first, because the air was so steady, and even through the dew, it was clear that there was plenty of detail there to be made out. For a while I hemmed and hawed about whether to go fish out an extension cord and blowdry the darned moisture off, but after a few minutes the sun began making its appearance and it was clear that I wouldn't have time to do it. Maybe I'll try it tomorrow morning.
10:00 p.m. 14 October 2000 PDT (0500 15 October 2000 UTC)
Saturday evening was the New Members's Star Party for the Los Angeles Astronomical Society. I've only been a member for about 15 or 16 months (depending on when you count from), and that counts as new, so I went, along with my wife, my son, and the Wocket (a Tele Vue Ranger).
Although I've technically "met" many of these people, I've only seen most of them by the dark of the night, so I didn't have any faces to match the voices to. And for whatever reason, I have a problem keeping names to voices without faces to hang them from. So it was nice to improve my recognition facilities, too.
The star party was being held at Garvey Ranch Park, in eastern Monterey Park (a community in Los Angeles county). It includes two baseball fields, both of which were being used, so the park lights were on at full blast, making it difficult to observe anything besides the just past full moon, double stars, and a handful of open clusters. I put the Coathanger Cluster (aka Brocchi's Cluster, aka Collinder 399) in the Ranger, which was one of the few scopes there that could frame it well. There was a nice gentleman there showing me and others nice views of tight doubles through his Tele Vue 85.
The object that drew the most oohs and aahs was the moon, of course. Even set behind the trees as it was, it still showed more detail than most other objects in the darkest skies. But it was still tantalizing detail, the sort that makes you want to see a bit more. So…
When I got home, I decided to set Opus up to see that "little bit more." The conventional wisdom is that the near-full moon is really the worst time to observe the moon (or deep sky objects, for that matter), but let's face it, it's still an imposing and beautiful sight at any time of the month.
I was in for a surprise. A kind of lunar tradition for me is to point the scope at the northern portion of the moon and track down craterlets on the floor of Plato. I seem to recall that the largest are a few kilometers across, which would not be so hard to see in the 5-inch SCT if the crater were near the center of the moon. As it is, it's quite a bit off-center and the craterlets are rather foreshortened. The best I've been able to manage previously is to see them haltingly and uncertainly, about three of them.
But on this night, those three showed brightly. The largest of them is near the center of Plato, and the other two were like clock hands at 12 o'clock and 4 o'clock. (I'm using a star diagonal, so the actual angle goes the other way.) Moreover, I could tell that the one at 12 o'clock was really a double craterlet—I couldn't quite resolve them, but they were very clearly elongated, and one could see a kind of "neck" between them. I could also make out, at the edge of visibility, two or three additional, quite smaller craterlets.
Note that the seeing was OK, but surely not spectacular. Jupiter and Saturn, which were rising just below the moon, were wavering rather significantly. This improved a lot by around midnight, so that the Encke minima was again evident in Saturn's A ring (and there was also excitingly a hint of a spoke in the eastern ansae of the B ring!), and Jupiter's GRS showed distinctly but palely, but the distortion caused by seeing was plain to see. Excellent seeing was not the factor that brought the craterlets into clear contrast.
This is, at least as far as I can tell, one of the better-kept secrets of lunar observing. If you have ever wanted to detect the craterlets, the near full-moon might furnish an unexpected opportunity. Certainly I had always tried it around day 9 or so of the lunation, and I've never had them show quite so distinctly.
Jupiter also made an excellent appearance, by the way; I don't want to make it appear as though I gave them short shrift. Particularly nice was Io emerging from the western or leading edge of Jupiter's disc, all of a sudden popping into sharp contrast perhaps a few arcseconds inside, and I got to follow it all the way out. I could also make out a couple of white ovals inside the STB, one just barely leading the GRS and one a bit further out, so as you can tell, the seeing was beginning to improve on toward the early morning.
7:30 p.m. 28 October 2000 PDT (0230 29 October 2000 UTC)
Last month, I posted an in-town report on a shootout between Opus, my 5-inch SCT, and Wocket, my newly bought 70 mm refractor. That review was done in my backyard with a limiting magnitude of 4.5 or so, and I was curious to see how the two scopes would perform under darker skies. So I set out to the Los Angeles Astronomical Society's dark sky site in Lockwood. It is about 85 miles from home, so it's no short trek.
It had been partly cloudy all day long, sort of a cottage cheese kind of day, and I'm sure that kept many people home, but not me. Other than this review, I also was eager to try out my new Palm star atlas, which I'd been working on semi-feverishly over the preceding week. I spent the afternoon at my son's school carnival, where I picked up a couple of Life science books, The Universe and The Planets, for a buck apiece. The latter is co-written by Carl Sagan, by the way, and it's amusing and puzzling in turns what we used to think about our fellow planets.
The drive to the site was a study in vacillation. For 10 miles, the sky would be clear, and then for another 8, it would be cloudy. This proceeded through a few cycles, and there were a couple of times I felt the whole affair would be a failure. But I arrived at the site with the sky about 60 percent clear, and began setting up.
It wasn't long before the mode of the night became clear. The clouds moved sufficiently fast that I couldn't study the views for very long; I had to keep dodging the hazy spots and pick and choose my spots. So I'm afraid this report isn't as comprehensive as it might be and there will have to be a Round 3 later on sometime. Still, I did get a few objects on which to compare the scopes. I think the results are somewhat interesting. I tried a variety of magnifications on both scopes, though the ranges were different. On the ranger, I tried powers from 15x to 80x; with the C5+, from 39x to 156x.
First up was the Double Cluster. Under suburban skies, this object was a dead heat between the two scopes, with the C5+ showing brighter stars, but not really more of them. Not so under dark skies. The Ranger was really outclassed by the SCT on this occasion, with the latter showing at least twice as many stars—stars that I'm sure were veiled by the light pollution back home. NGC 869, the eastern and dimmer of the two clusters, was particularly more interesting in Opus than in the Wocket; I think that cluster is more uniform and therefore more haunted by haze or by smaller aperture.
Next in line was M31/M32/M110. Unlike before, both scopes showed all three galaxies. Only the Ranger was able to show them all completely in the same field of view at once, of course, but it was not viscerally as compelling as I expected it to be. I'm tending to give it the benefit of the doubt, since the haze was no doubt a factor. (That underscores a provocative point to observers who are city-bound: You don't see clouds under dark skies, since there's nothing to illuminate them from underneath. What you see are fewer stars and less contrast.) Opus showed the gauzy dark lane at the northern edge of M31, and a hint of the lane beyond that; all that was visible in the Ranger was that one side of the galactic center was sharper than the other.
Then I went over to the other side of the sky toward M27 and M57. The planetaries are exciting in the Ranger; M27, the Dumbbell, showed as a bright bowtie in the sky, with just the right wrinkles—a few hints of structure that one could intimate were correct, but they never came out loud and clear. Again, the Wocket was outclassed; Opus revealed the fuller, football shape of the nebula, stretching out in arcs of dim light. The difference was less pronounced with M57, possibly because it's a smaller object. Under dark skies, the Wocket is every bit as capable as Opus of showing M57's smoke ring or blood corpuscle shape.
Around this time, a few visitors to our star party were asking us to show them some objects, so I volunteered the Coathanger, which is the sole province of the Ranger. The C5+, even were I to install the reducer, couldn't do this object justice. Somewhat to my chagrin, the Coathanger is a less conspicuous object under dark skies than under bright ones; for whatever reason, just enough other stars show up to make the asterism less obvious. Fortunately, I was able to tell the cluster's story (including the discovery of its non-cluster nature) fast enough to make up the difference.
Another object for public viewing was M11, the Wild Duck cluster. At home, it is a triangular, iridescent blur, but under dark skies, it is an object of almost incomparable beauty. Easily a hundred stars are visible at a moment's glance through the C5+; perhaps 50 or so showed themselves in a tighter configuration in the Ranger. I could have watched them forever, but the clouds were moving and it was important to give everyone a chance to see the cluster.
At this point, deciding that I needed to make the most of what remained on this night, I put the Ranger away and concentrated on Opus. For my next object, M2, a globular in Aquarius, I pulled out my PalmAtlas and punched in the coordinates. At power 2, PalmAtlas shows me a FOV that is about what can be seen through my finder, and the appearanced matched very well, to my eye. Put my scope right on the target; very exciting! I think that with the proper enhancements, my little program is going to make starhopping more enjoyable.
The next object was the Double Double, epsilon1,2 Lyrae. I pulled out the big gun, the 6 mm Radian, yielding 208x. Rather unfortunately, the stars all had little halos around them; the corrector plate must have dewed over, despite my dew cap. Still, all four balls were visible with patience, and one by one I led the visitors to the scope, this time making sure they all knew where the focus knob was, because focus is crucial for the Double Double.
One gentleman had difficulty seeing anything at all through the scope. I suggested moving his head back and forth, to make sure he was in the right place, with respect to the exit pupil, but no dice. He couldn't see any white glows, no constricted field of view; he couldn't see anything at all. I was puzzled, and asked if I could take a quick peek. He assented, and I took my seat at the controls. Peering into the eyepiece, I could see that he was right; the view was pure black. "That's funny," I thought, "the scope must have gotten nudged." I peered through the finder to relocate myself, and that view was pure black. That was no dew on the corrector plate—that was dew in the sky…clouds! It had completely clouded over in no more than half a minute.
Well, at that point, all the visitors departed, and that left just me and Larry, a long-time club member and sort of the site proprietor. I put away the scopes and brought out my Coke and crackers (one benefit of the clouds was that the ground retained quite a bit of heat; it was only about 40 degrees, relatively balmy), and we chatted for a while. After about a half-hour, the sky miraculously cleared. I took the opportunity to get out my binocs—my 10x50 Celestron Pros, which I always have with me in case of an astronomical emergency, and this surely qualified. I spent the next half hour happily chasing down some larger deep sky objects. Mira was near maximum, so I tracked that down as well. Larry also got Jupiter and Saturn through his 8-inch Celestron orange tube, but the seeing was indifferent and I can get better views, I think, at home. By that time the cloud cover was coming back in, and we raced to get M37, which was then just lying above the horizon. It's a wonderful sight in an 8-inch scope and the last one we got before we were socked in again—this time for good. Still, it was a nice reprieve and I'm certain the binocs were happy to get some use for a change.
In conclusion: It is often stated that aperture wins, both in good conditions and in poor. It's also evident to me that it wins even more under good conditions than in poor. The darker skies (though not as dark as I would have liked, due to the clouds) didn't narrow the gap between the larger SCT and the smaller refractor; rather, it widened it. The outstanding feature of the Ranger continues to be its small size and consequent portability, and its wide true FOV. There are objects that should show better in the Ranger. By and large, though, I find viewing better through the larger C5+.
Sometime Soon: Round 3 (just to be fair to the Wocket)
Copyright (c) 2000 Brian Tung