Late August often provides amateur astronomers with the best observing conditions in Northern California. Taking advantage of the good weather forming up for the weekend, I launched out on a three day astrophotography trip to near Yosemite. The night of the 27th into the morning of the 28th was noteworthy by its calmness and transparency.

Most Sierra locations suffer from atmospheric turbulence flowing off of the central valley, but this was not to be the case this evening. Mild temperatures, and zero wind prevailed early on. Hardly a star was twinkling in any observed direction. The ST-4 autoguider also betrayed the unusual conditions by providing 0/0 readouts during a pair of long exposures of the Pelican Nebula. That typically means that no correction to the RA and DEC directions are occurring. The ST-4 is so sensitive, it typically will track on atmospheric seeing. After about 140 minutes of this (all the while wondering if the ST-4 was even doing its job), I decoupled the camera and swung the Astro Physics 7" f/7 refractor to Jupiter which was just crossing the local meridian. 300X revealed a vista of pastel yellows and browns, with a hint of red-orange in some of the southern most Jovian cloud belts. I counted 12 belts, No GRS, but a large brown cloud was visible. Temperatures hovered around 52 F, and the 7/7 has been suffering from astigmatism in the lower temperatures. (Something to do with the objective cell being too tight) Yet, the image was excellent, with Jupiter's moons exhibiting solid, observable disks.

An OIII filter was slipped on a 35mm Panoptic eyepiece for a quick peak at the Pelican/North American Nebula complex. A great view indeed, but nowhere near as good as John Kukelweitz' 18" views from Lassen '96. This was one of the few times I pined for more aperture. Still, there were visible twisted dark structures near the tip of "Florida" and the Pelican form was unmistakable.

Back to astrophotography. Several pix were done of M31, now riding high in the east, with the telescope reaching near vertical at the end of the second photo run. Sky transparency had remarkably improved past midnight. 10 stars were counted visually without optical aid in the Pleiades. M33 was also naked eye. The sky itself had taken on a granular appearance. I suspect that a number of 7th magnitude stars were just on the edge of visibility. Orion, just clearing the trees, was wreathed in a veil of glittering 6th magnitude diamonds. Time for one final shot at the Pleiades.

Through the telescope, the Pleiades was the finest that I could remember in 30 years of observation. The Merope nebula was huge, filling about 80% of the 35 Panoptic field. Lots of fine structure and faint wisps of nebulae near Electra. In fact, all of the bright stars had glowing halos of gas extending well outside the field of view.

M33 was interesting for its unusually clear spiral form against a glittering star-sprinked sky background. Lovely.

M31 looked like a Tony Hallas photograph. Dark lanes were mottled, star clouds were bright and well defined. Why take photos when the viewing is as good as this? Hmm... must be some incurable disease at work. I wonder if the Betty Ford Clinic has a cure?

At 5 am, a -1 magnitude bolide meteor dropped to the northeast, with a great flameout and breakup at the end of its 3 second life. Hurrah!

Running through the Pleiades and out to Saturn, the band of zodiacal light was visible. This actually put a lot of skyfog in my resulting images of the Pleiades. The zodiacal light reminded me of a great cosmic finger pointing to Saturn. At 300X Saturn was magnificent. Subtle coloration could be detected within the rings, with momentary glimpses of brightness variations where the Enke division should be. The binoviewer revealed pronounced polar darkening and subtle details in the broad cloud band on the planet.

By this time I was very much toast. 300+ minutes of astrophotography and a thermos of coffee later I was both buzzing and bleary-eyed at the same time. At the first signs of astronomical twilight, telescope power was shutdown and eyepieces were put away. Another great night reminding me why I love this hobby so much.

jg

note:

One of the great things I like about astrophotography is the record you get of such a great night. The resulting images of the Pelican and M31 are amazing for their detail, contrast, and color saturation.