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Viewing Notes
May 19, 2001
Arizona-Sonora Desert Museum
Obsession 20" f/5 reflector
Last night was our local astronomy club's star party event at the Arizona-Sonora Desert Museum. The viewing area was in the first two rows of the parking lot, near the entrance to the Museum. There was quite a turn-out, with about 18 telescopes and about 75 to 100 visitors. People started arriving around 7:30 or so, but the sun was just beginning to set. I took some pictures while there was still enough daylight left.
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Jupiter was about 20 degrees above the western horizon and, as expected, not in the steadiest of skies. The primary was not at thermal equilibrium and this also contributed to a degraded image of Jupiter. But people still wanted to see what Jupiter looked like through a 20" scope. Several bands were present at at 95x, but no cloud structure could be discerned. Io, Europa, Callisto and Ganymede were all visible, as was the star SAO 76962. This star was just as bright as Io and confused many people into thinking they were actually seeing 5 satellites. Fortunately, I had my Palm Pilot with me and used J-Moons! to identify the satellites.
Mercury was very high in the western sky, probably 5 degrees east of Jupiter. A guest (very knowledgeable) pointed this out to me as I was wondering what to look at after Jupiter had disappeared behind some clouds. The planet looked to be about 50% phased (actually was closer to 41%). I was really surprised by how high in the horizon this was - I'd always assumed Mercury was always hugging the Sun.
Around 8:15 I positioned the scope to M51, The Whirlpool Galaxy. Even in twilight, the scope pulled in enough photons so people could actually see the spiral arms. I spent about 45 minutes on this with perhaps 50 people taking a peek.
M13 was the next target because Hercules was high enough in the sky, although captured by the some of the skyglow from Tucson. This brought crowds of people to the telescope as rumor got around the star party of the view of this magnificent globular cluster. I spent over an hour viewing here. I had to shift back to M51 because of some clouds passing through. There was a period of about a half hour or so that almost the whole sky was covered in clouds. The crowd began to thin and some members started packing up.
For the people remaining, I positioned the scope to M81 & M82. About only 5 or 6 people got to take a peek before the clouds engulfed that portion of the sky.
M57, The Ring Nebula, was high enough and in an area of sky free from clouds so I positioned the telescope on it. Even though we were looking only 15 degrees above the horizon, through some of the skyglow of Tucson, the nebula was pretty decent. I switched eyepieces from the 31 Nagler to the 22mm Panoptic. This darkened the background and helped bring out the nebula. For many of the visitors this was their first peek at this. it was rewarding to hear the kids shout "cool" when they looked through the eyepiece.
The clouds dissipated during the time we were looking at M57 so I spent the remaining time alternating between M51, M13 and M57.
On a side note, I was having difficultly with keeping objects in the field of view and was wondered if the tracking platform was malfunctioning. Because of the long, steady line of visitors I never got into proper trouble shooting mode. I climbed up the back side of the ladder and repositioned the objects instead. Then, in a moment of discovery, I realized that I didn't have the platform polar aligned. In fact, I was off more than 30 degrees (too far east)! No wonder the platform wasn't tracking. I've always known that this platform would work with just a very crude polar alignment, but I now know that "crude" has to be closer than 30 degrees!!!. Once I repositioned the platform, everything was just fine.
There was a pretty spectacular lightening storm to the south of us, but other than the occasional flashes through the telescope, it really wasn't too bothersome.
