My Observing Log: May/June 1999

12:30 a.m. 20 May 1999 PST (0730 20 May 1999 UTC)

I left the scope out to cool around 8:00 p.m. last night. Obviously it doesn't take that long, but having it outside the house is more likely to encourage me to go out there come midnight or one.

By the time I finally got out there, it was 12:30 a.m. PDT (0730 UTC). The air was crisp and cool but not uncomfortably so, even in a T-shirt and shorts (about 55 degrees). I quickly set up my workbench "tripod" and set the C5+ down on it, and put in a 9 mm ortho.

The seeing was excellent—a 7 in my books—so I decided to insert a Barlow and try observing at 280x. It took a while for my eye to get accustomed to the view at that power—perhaps half a minute—but once I did, the detail was pleasing. I did not compute the CM, but I did recognize Mare Acidalium, Mare Erythraeum, and Sinus Sabaeus, as well as the north polar cap. It was indeed small, but bright, and the steady seeing made it quite distinct. From the view, I would estimate the CM at about 15 or 20 degrees, but I don't remember my Martian geography very well.

In the C5+, Sinus Sabaeus really only showed its head well—the tail extended toward the edge of the disc and was indistinct at best. On the other end, Mare Acidalium showed quite a bit of mottling within its shuttle-shaped (to me, anyway) borders. There were also some dark patches to the leading side (celestial west) of Mare Acidalium, and also on the leading edge of the Martian disc, further south, at perhaps 20 degrees S latitude. Closer to the Martian equator, also on the leading edge, there was a small patch of white clouds. In contrast, there did not appear to be any clouding over Chryse.

Finally, concentrating on the NPC, I seemed to detect a pair of small dark fingers flanking it, extending about twice as far as the NPC itself. I say fingers because there appeared to be a light patch of Martian sand in between them. However, I wouldn't characterize this final sighting as anything better than questionable.

Overall, I was amazed by how much darker the features seemed than the last time I saw them a few weeks ago. Perhaps the Martian sky has cleared somewhat. Unfortunately, after all that waiting, I had to cut my observing session short, as a new patch of clouds appeared— this time, terrestrial. I'll try again in a couple of nights, as there seems to be a front of sorts moving in…

sketch of Mars

Later note: Here's a sketch I made of how Mars appeared that night.

12:30 a.m. 21 May 1999 PST (0730 21 May 1999 UTC)

Under virtually identical conditions, the disc of Mars looked almost exactly the same. There now appeared to be only the equatorial cloud on the leading edge; the one at 20 degrees S latitude had apparently dissipated. The NPC was distinctly visible, but seemed a little smaller, but it's hard to tell since it's smaller than the Airy disc of the C5+.

Unlike last night, I used some of my time out to look at another object, the Ring Nebula, M57. I hadn't seen it since last summer. Now, M57 is such a hoary old object that you might well wonder why I would even bother looking it up. Well, Santa Monica has a fair share of light pollution. At its 25 to 30 degree altitude at the time that I was observing, it is a fair challenge; Vega is the only star in Lyra that is even visible by the unaided eye. So I view M57 as sort of a test of my observing skills—not an extraordinarily onerous one, but observing it with the C5+ under these conditions is akin to observing it with a 30 to 40 mm spotter under dark skies.

I had also recently purchased a 32 mm Tele Vue Plossl, and I wanted to try it out. So I slid it in, and used my 6x30 finder to locate the approximate spot of the Ring. Now here is where I think all those Telrad users should relax. Under these skies, a Telrad is basically useless. If all I have is Vega, and I can't see the exact direction that M57 is from Vega, then how can I use the Telrad? Instead, I use the regular finder almost exactly like a reflex finder, and once I'm close, I can use the extra aperture and magnification of the finder to locate dimmer field stars. There are certainly conditions under which the Telrad (or similar device) works great; I just don't live in them, and I suspect many other people don't either.

Anyway, rant off. I found the right field with no problem at all, and the 32 mm eyepiece showed a faint blob in the expected position when all the other stars were sharp points. (I should point out that even with the 32 mm Plossl, the sky was bright enough that there were only about 10 or so other stars in the field.) Replacing the 32 mm with a 15 mm Plossl with an UltraBlock refined the view perfectly. At 83x the Ring was now a well-defined donut; the center was not black by any means, but there was a marked darkening internally. Very nice!

I also tried to refind the Dumbbell Nebula, M27, but it was way too low and completely washed out. I should be able to try for it in a relatively short period of time, though.

7:30 p.m. 25 May 1999 PST (0230 26 May 1999 UTC)

Just a quick 15 minute session today, looking at the twilight views of the moon and Venus. Venus first: I tried observing at 167x and 280x. The seeing was good enough—again a 7—to support such powers. At 280x, I seemed to see a hook-shaped darkening toward the southern end of the terminator; this wasn't visible at 167x. I don't have a dark violet filter, so I tried the UltraBlock instead. This didn't reveal any additional detail (but I didn't expect it to, so I wasn't terribly disappointed).

The moon was nice and steady, being nearly overhead at the time. One of these days I will finally break down and study the moon enough to do some serious observing of it, but for now I just scanned over it and marveled at the view. I looked for the craterlets of Plato, as I often do. When the seeing steadied even further, I could make out the central craterlet, but that was it. Maybe I've waited too long to detect those.

Copyright (c) 1999 Brian Tung