Saturday, October 10, 2009

Starparty from the Edge of Civilization

It had been a while since Melinda and I had been under a dark sky, so with 10pm moonrise scheduled, yesterday we headed for the hills! To keep it simple and provide a dark northeastern sky, we went up towards Mount Lemmon's Geology Vista, a really nice pullout about 14 miles up a fine paved mountain road. Total driving time from our house is right at 60 minutes, and you couldn't do much better in so short a drive if you don't care much about your southern sky (towards Tucson).

While the weekend forecast had been for perfectly clear skies, as we stopped for a snack before heading up the Mt Lemmon Highway, we saw the ominous sign - Sun dogs! Usually a sign of gradually increasing clouds, it was pretty at the same time. Undaunted, we figured we'd pretend we didn't see them, and would at least get a nice scenic drive out of the trip.

One of the interests in going out was to take a picture for a friend of mine - she wanted a photo of the Andromeda Galaxy that approximated it's naked eye view, including some nearby star or constellation references. Of course, it is always nice to provide some terrestrial landmarks as well, like the horizon or trees that "bring it down to Earth". Since Andromeda was well up at dark, a photo would have to be taken very soon - before you know it, a few more weeks of the Earth's trip around the sun will have Andromeda nearly overhead at dusk... So we set up the 14" Celestron to start cooling down for later observing, and I set up my little tripod and tracker for a wide field camera shot. With a 20mm lens and short 30 second exposures I was able to get the Great Square of the constellation Pegasus at right, all the way over to Cassiopeia's throne at left. The fuzzy patch at center is the Andromeda Galaxy, the furthest you can see with your naked eye - about 2.4 million light years away (multiply by 6 trillion miles or 10 trillion kilometers light travels in a year to convert to your car's odometer distance).

Geology Vista is a nice spot - with a remarkable view of the canyon and rock formations to the east, and the view takes in the entire range of the Santa Catalinas, of which Mount Lemmon is the peak, to the Rincon Mountains to the southeast, and Santa Ritas 30 miles to the south, and the entire Tucson Valley as well. There was surprisingly a LOT of car traffic - it was a Friday night, of course, and there a lot of residents that live on Summerhaven at the top of the mountain among the ponderosa pines and commute to jobs in the urban jungle. The picture here is 11 minutes long at F/5.6 with the ISO at 200. It shows the car headlights lighting the highway and outlining the canyon and rock formations (along with the lights of Tucson). The Pleiades are rising in the east, and the light glows of Safford and Wilcox far to our east is visible off the thin clouds.

As predicted, the thin clouds rolled in, but didn't bother observing too much. We got some great views of Jupiter and a few impressive sky objects for a passerby who claimed fate brought her to join us and enjoy the sky. After she left, Melinda and I tried some pictures of Jupiter with the C-14 and her camera - and we discovered again how difficult it is to try to retain some detail on very bright disk of the planet and still show the 4 Galilean moons that orbit Jupiter. The shot here shows the moons clearly, but none of the cloud bands that show up on shorter exposures (but then without moons). From left to right is Callisto, an overexposed Jupiter, Io, Europa and Ganymede. Io and Europa were moving quickly, and we're hoping to demonstrate that motion somehow in a subsequent post.

Realize that while we were over 6500 feet, we were still close to Tucson - likely less than 15 miles, and a glance south showed the "pretty lights", or as pretty as astronomers would allow light pollution to get. I observed Comet Hale-Bopp many times from this site and the sky was inky black, but it was far from it last night - perhaps it was the thin clouds that didn't help, but certainly Tucson continues to spread to fill up all the semi-level space that is available between the mountains. Be sure to click on the image for the full-size view.

After packing up before moonrise, we paused at Windy Point, just a quarter mile below Geology Vista, where the Tucson lights picture was taken. While walking back from the edge of the hill, I noticed the crosswalk that led people back to their cars if they parked on the northbound side of the road, but appeared to be leading right towards the Pleiades or Taurus. The hillside is lit up by Tucson's lights, and there is a halo of light over it from the just-risen moon. The appropriate title would be "Crosswalk to Pleiades". If only the sky were so accessible!

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