10:45 p.m. 3 July 2000 PDT (0545 4 July 2000 UTC)
My recent outing in search of M71 did help me get back into the swing of things, in a way. This evening I began early by setting up my Celestron Pro 10x50 binoculars in the backyard to catch Albireo. My 5-year-old son, who thus far hadn't shown much interest in Daddy's hobby, decided to take this opportunity to have a looksee. I'm not sure if he saw it, but it was nice to see him wanting to look.
After we put him to bed, I set up the Big Iron, if you can call 5 inches of SCT under light-polluted skies a "Big Iron." I suppose compared to the binoculars it is. I collimated on Vega, and noted that the seeing was pretty good. Having just taken the scope out of the house, I figured it was too early to determine whether the small fluctuations that remained were due to tube currents or seeing. Still, with the Vixen zoom on the low-power end, epsilon Lyrae 1 and 2 were both barely split at 52x.
I began with the Ring Nebula, M57, which showed up nicely, or as nicely as you can expect from mag 4.6 skies. Then on to my one new target of the night, M56. M56 is a globular cluster not far from M57—if you go from beta, past M57, past gamma, you find yourself in a "checkmark" asterism of four stars pointing south, and just past the tip of the check is M56.
It's a dim globular, at about magnitude 8.4 (reference O'Meara again), along one side of a triangle made of 10th-magnitude stars. With the bright skies, it did take some work to get at it, but find it I did, with the best view at somewhere between 16 mm (78x) and 20 mm (62x) on the Vixen zoom. At these powers, the sky background dimmed sufficiently to reveal something of an elongated X-shaped crosshatch, with one axis running approximately north-south, and the other running approximately northeast-southwest. But this was a very tenuous detail, and I'm not quite ready to sign my name to it. I plan a trip to Lockwood, the Los Angeles Astronomical Society's dark sky observing site, later this month, so I'll recheck the globular then—it should be in prime viewing area for months to come.
Then over to M27, to see how that looked (very clotty, I thought, with the southern clot much brighter than the northern clot). One quick glance at Albireo through the telescope (I still like the binocular view better), and then it occurred to me, because of the recent thread running on SAA, to look at Porrima, or gamma Virginis. I had seen it in April of last year, when it had narrowed to about 1.5 arcseconds separation, and now it should be about 1.3.
I brought out the 6 mm Radian, and centered on Porrima. Nothing, except some fleeting moments of elongation that I eventually decided was just atmospheric dispersion, since one end was red and one end was blue. I decided to put on the Barlow, and was rewarded with an exceptionally steady view at 417x. But definitely no elongation. I was very puzzled, since I made my split of Porrima at 278x last year, and it was fairly clean too.
I looked at the sky chart and discovered my problem, which would have been obvious if the sky had not been so bright. I had not been focused on gamma after all; it was zeta, somewhat to the east. I quickly looked back up to see if I could find gamma, but I could not. I scrambled around the backyard looking for a spot from which I could see it, and finally found it in the corner. I hurriedly moved the scope, tripod and all, over to the new location, and tried to track down Porrima, but alas, it slipped over the obstruction (my house, sadly) just as I began to observe.
As a sort of consolation prize, I pulled the 417x powerhouse over to the Double Double, and was astounded at the steadiness of the view. Four perfect Airy discs, each surrounded by a thin but dimly visible first diffraction ring. The DD was split at 52x, as I mentioned, but it was no comparison—at 417x, the southern pair was absolutely clean, with about enough room for another Airy disc in between the two actually there. The northern pair was similarly well-resolved. It was awesome, but at the same time terribly disappointing not to have been able to catch gamma Virginis with such excellent seeing. The irony of it being mostly a planetless night (with the exception of featureless Uranus and Neptune) didn't escape me either.
11:00 p.m. 4 July 2000 PDT (0600 5 July 2000 UTC)
Having spent most of the evening at the house of some friends for fun, food, and relaxation, we still returned in time for me to finish what I started yesterday—a split of gamma Virginis. I quickly set up the scope in a location where the binary would be in view. Even at this time, I found gamma barely 3 or 4 degrees above the roofline, and dipping fast, of course. I quickly did a test focus on the Double Double, again using the 6 mm Radian barlowed to 417x. The seeing proved to be not as good this evening as on the last, but sufficient for the job. The Airy discs themselves were steady, all right, but the first diffraction rings, which were almost perfectly steady the previous night, were dancing around somewhat tonight.
Still, pointing Opus over to gamma soon produced success. It was immediately obvious that it was split. The turbulence was made worse by gamma's low altitude as well as the relatively warm roof, but in the moments of steadier seeing afforded even by those factors, I could see a thin black space between the two components. I judged the separation to be a bit more than half that of the Double Double's southern pair, which would put it at about 1.3 arcseconds. The position angle I determined by swishing the RA slow motion knob back and forth and seeing what angle the line connecting the two stars made with the motion the knob caused; I arrived at a value of about 260 degrees (or 100 degrees, depending on which one you consider to be the primary—the stars are almost equally bright). As I noted on sci.astro.amateur, this is one application where you really want extra high magnification.
For my next trick, I turned the scope over to Izar, epsilon Bootis. People have called this a mini-Albireo, and it's not so far off. With the high magnification, Izar does have the bright golden primary and dimmer blue secondary, at nearly the same separation as Albireo gives at a mere 10x. Of course, through 50 mm binoculars at 10x, Albireo looks pinpoint, while the Izar binary shows obvious Airy discs at 417x.
The rest of the short session I spent in getting M11 into the wide FOV of my 32 mm Plossl, for my son to look at. He seemed to indicate success, although it wasn't absolutely clear. I don't want to push him into it, though, so I think I'll stop pestering him for a while.
9:00 p.m. 29 July 2000 PDT (0400 30 July 2000 UTC)
My fourth trip to Lockwood (the Los Angeles Astronomical Society's dark sky observing site) went smoothly, but poorly—we were mostly clouded out. It was a disappointing trip for me, especially after spending the day collecting a list of 31 of the 35 remaining Messier objects I had to observe. (The other 4 were not available on this day.) The interesting thing about mostly cloudy nights at a dark sky site is that you can't really tell that it's cloudy by seeing clouds; all you notice is that much fewer stars are visible than usual. I'm sure it's a common phenomenon to non-city folk, but it's still weird to me.
I did get to observe two objects, both at fairly low powers (39x), at which very little detail was visible. I did note that M63 was elongated east-west, and that M94 seemed to be mostly round with a brighter core. But other than that, it was mostly a lost night. I did spend some minutes chatting with the LAAS newsletter editor, and signed on to do some observing articles to bulk up the content.
11:00 p.m. 4 August 2000 PDT (0600 5 August 2000 UTC)
Just a quick half-hour session tonight, with more city lights but a much clearer sky than at Lockwood. The end result was that it was essentially as fruitful at home as it had been at Lockwood. The ZLM was about 4.5, a little worse than usual despite the moonless skies, I think because the humidity was high, meaning that what light pollution there was was scattered more efficiently. I didn't think to measure the seeing precisely, but it seemed to be in the BuBl 2/1 neighborhood. (Remember that this is a 5-inch SCT.)
I decided to pick up one more object on my list: M92. Since I had seen M13 a number of times before, I was surprised that M92 wasn't in my log, but it isn't. Maybe I felt M13 was too unimpressive at my old site, and with M92 playing second fiddle, I may have thought it was too dim to see.
I began my night with M7, just as a quick look. Beautiful as usual. I then moved over to M13, large and imposing, but so smooth that only a hint of granularity could be seen. M92, surprisingly (to me), is much denser, with a partially collapsed core. It showed best at about 87x, with a condensation at the northeastern end, and flares out to the south, west, and northwest.
I also took quick peeks at M22 and M28, both Sagittarius globulars. M22 is still a magical sight, to me the best of the globulars we can see from the northern hemisphere. At 39x, the globular is quite granular, and if I move my gaze around the cluster, averted vision makes the brightest stars pop in and out like fireflies. Fantastic!
9:00 p.m. 10 August 2000 PDT (0400 11 August 2000 UTC)
Tonight, I decided to finish off some globulars remaining on my Messier list. Despite a nearly full moon hanging around Scorpius and Sagittarius, the limiting magnitude in the area was about 4.5, probably due to low humidity. As if to compensate, the seeing was very bad—perhaps Bubl (Bulk/blur) 6/2 arcseconds.
To warm up, I looked at the moon and M7. M7 is still awe-inspiring at 32x, with about 50 stars visible in the core, just upon first viewing. In the city, this open cluster is an excellent lesson in the benefits of additional magnification; as I jacked the power up to about 98x on the zoom, another 25 stars or so popped into existence as the sky background dropped away behind them.
My first globular was one that I had seen before, but not in the city: M4. I remember the first time I saw it—I naively thought that since it was about magnitude 5.6, it should easily be visible just about a couple of degrees west of Antares, even sitting (as it was then) only 10 degrees above the horizon! Of course, I saw nothing at the time. This time, I was careful to place the globular precisely at the center of the field of view, and adjust magnification to optimize visibility. M4 was definitely but dimly visible, with best visibility at about 19 mm on the zoom, for 41x. I could see no detail, however.
M9, my first new globular, was even closer to the moon than M4; the limiting magnitude in the area of M9 was closer to 4.3. M9 was barely visible, showing up best at a surprisingly long 24 mm (32x). Again, no detail.
Things picked up a little after that with M10. This Ophiuchus globular was easy to find and best seen at 15 mm (52x). It is much more distinct and somewhat larger than M9. I could begin to see some detail, a SSW-to-NNE axis through the globular that ended in an W-facing "lobster claw" at the NNE end. That was the only detail visible.
M80 was a fascinating globular. It's just a little NNW of M4, halfway between Antares and beta Scorpii, the top of the scorpion's head. It lies in a narrow triangle of 8th-magnitude stars. This globular's core is very condensed indeed, and it just took magnification endlessly. I found it best at the full 8 mm end of the zoom, for 98x. There seemed to be little in the way of large-scale detail, except for three bright spots, at WSW, NW, and NNE.
M107 was my hardest target of the night, lying just about 3 degrees SSW of zeta Ophiuchi. It's magnitude 7.9, hardly an unreasonably dim object, but it's a full 10 arcminutes across, spreading that light out thin. As it was, it represented the absolute limit of my skills, under these particular conditions, just to see the darned thing. Needless to say, I could see absolutely no detail in the cluster.
I returned to the vicinity of M10 to capture M12, best seen at 10 mm, for 78x. While not as distinct as M10 on the whole, it had a very obvious feature: a checkmark shape on the north side, with branches extending to the NW and NE. It is close to a 10th-magnitude field star.
My final globular for the night was M14. It's at the third corner of a 45–90–45 triangle anchored by xi Serpentis and nu Ophiuchi, and north of xi Serpentis. It was best seen at 16 mm (49x), but dim and unimposing. One interesting facet of observing M14 under these conditions was the exceedingly narrow band of magnifications with which the globular could be seen well. I couldn't be sure that there was much detail in my view, but I did seem to sense two tails, one to the WNW, and one to the NNE. (The latter is not represented in O'Meara.)
I finished up with a glance at the moon. Even with vastly suboptimal seeing, it's still an awe-inspiring sight. I found my attention drawn to the bright Proclus; it almost looks as if it were created yesterday.
Copyright (c) 2000 Brian Tung