Grant Ranch, 10 July

by Matthew Buynoski


It has been months since I've managed to get out observing. First one thing (mostly weather), then another (sore shoulder), etc. But, finally, everything cooperated and I ended up on Halley Hill in Grant Ranch park before sundown... having only forgotten the copy of S&T I was to have brought along for reading until the stars came out.

Weather was fine for shirtsleeves all evening long, though it did start to get a tad cool after 11:30. There was haze, but not too much. Looked like monsoonal type clouds away to the south and east, too, but fortunately they did not come our way and seemed to recede later. Limiting mag. near the pole was about 5.3(?) as all but one of the main stars of Ursa Minor were visible. It was better to the east, but to the west (as usual) the light dome of San Jose wiped out everything but Venus.

For some reason, half the HVAG crew didn't get the word to go up to Halley Hill, and others of us were off at an event up at Lick. So we had only 4 scopes (8" dob, 2 8" SCTs, 10" SCT) and one pair of 20X80's set up. There were more scopes down the hill, which got most of the public traffic, as they were much more obvious to anyone coming by. In any case, we had perhaps 6-8 public visitors during the evening, and that's including including the ranger who came by.

Viewing was, by and large, old favorites. There were a few less-common items, mostly because someone (guess who) just had to hunt down itsy-bitsy globulars and micro-open-clusters all evening.

The festivities started with sunspots. The seeing was none too steady but there were several nice groups, with each group mostly spread out as a line of spots. Not much detail could be discerned with the unsteadiness of the air.

Venus was next, and all scopes leapt at it. This wasn't because it was all that exciting, but due to the fact it was the only thing out in the sky at the time. The phase showed nicely. Seeing was thoroughly unsteady but it didn't matter much as there's no detail on Venus anyway. Mars popped out and got attention, but was generally disappointing. No details at all could be seen as it bounced around the field of view.

Vega came out, and I put the diffraction grating on it. All 4 main hydrogen lines were visible, with the alpha and delta "coming and going". Beta was always there and gamma almost always. Arcturus was out not long after and showed a nice spectrum but no obvious absorbtion lines. Antares, however, was another matter and perhaps 10-12 lines could be seen (some intermittently, to be sure) in its spectrum. I gave the usual little spiel about the relative amounts of red, orange vs. green, blue in the spectra of Vega (A), Arcturus (K), and Antares (M) and its relation to star surface temperature.

As things started to pop out, I took a look at M4 because it's right there by Antares. But as the other 3 scopes were well into doing the classic favorites by then (I remember at least M's 4, 6, 7, 8, 11, 13, 17, 20, 22, 27, 57, and 92 being announced for viewing) I slipped off into the less-beaten track with 6144. Working my way around down the backbone of Scorpius, I stopped at 6242 (a nice little cluster) and then onto the trio of 6231 (very fine...did you know this cluster, which is loaded with O-type stars, is intrinsically almost at bright as the whole of omega-Centaurii with its million stars?), Tr24, and Cr316. These three comprise the heart of the Scorpius OB association (or so the books tell me). Emission nebula IC 4628, which is in the middle of Tr24, I could not see. After that it was on to 6268 and 6281, "relatively unknown" open clusters.

Aside: the dynamics of the star party. We had two "fast find scopes" (one an LX200, one a C8 with DSC's), so that there were always several items on view for the visitors, even with one scope off looking at "weird stuff". It turns out that the finding time for the objects (even my relatively slow star hopping) was rather unimportant. The viewing time for all the people present at each object was long enough that there was always something different available at once on another scope. Most of the time they went from the C8 to the LX200 and back again, but now and again I and the guy with the dob would chime in with something as well. I might add that I was enjoying having others find all the classics, so I could run over and ogle them and then go back to finding oddball stuff.

Back to astronomy...6302, the bug nebula, was next. It showed fairly easily, but not with a huge amount of detail. This one excited more that the usual polite interest, although I suspect more from the name than the actual view itself. Next on to H16, a decent cluster but not anything to write home about, and Shaula. I put the diffraction grating on Shaula to see how much color this 1.6 mag star showed (spectra eventually turn grey to the eye if the star is too dim). Answer, some but much less saturated than for the three stars viewed earlier. After this I tried globular 6380, but it was completely invisible. 6441, however, showed up nicely. Curiously, those of the visitors who viewed it were more interested in the bright star G-Scorpii (it was in the same FOV) than in the cluster itself. There followed a quest for 6453, which is a small globular at one side of M7. I eventually found it, but it was very, very faint. Not being sure, I asked the LX200 owner to slew to it. He did, and the star fields matched. With his larger aperture, it was more visible but still very dim. A side benefit of looking for 6453 is that you get to do it while M7 is sparkling in the field of view.

After that, it was a globular tour of the spout of the Sagittarius teapot, including 6624, 6569, 6558, 6528, 6522, and M69. While these interested the other astronomers, the visitors generally found them not very exciting. Ah well.

Not long after this the visitors all vanished and I spent a little time on M22 and M8 (both of which I'd missed earlier in the computer-equipped scopes). Just kicked back and relaxed with a long, unhurried view of each. Then it was time for a little lie back (Halley Hill has some installed benches) and just watch the sky wheel by...utterly relaxing. Milky Way was visible from the south up through to Cassiopeia, before fading out into the Livermore sky glow. One nice meteor trail appeared, in Cygnus, burning out before making it to Aquila.

Fine way to end the festivities.