Newsletter of RAS (Richmond Astronomical Society)
August, 2002

Visit our web site at www.richastro.org

Next meeting--Saturday, Aug. 17

Picnic instead of regular meeting in August
by Terry Barker

Our annual picnic date has been set for Satuday, Aug. 17, at the observatory. The backup date is Aug. 24. We'll start at 6:30 pm. Susan Brubaker is taking care of coordinating the food, so you might contact her to see what we need. Her email address is aviatrix@pipeline.com, and her phone is (804) 932-9347. If you need directions, call one of the board members, as we hesitate to put directions in the newsletter, for security purposes.

Last meeting
by Terry Barker

Share Table – 

• Ken Wilson brought in an invitation to the Okie-Tex Star Party, scheduled for Sept. 29. A long away, but one of the larger amateur events in the country. Ken also gave us the latest update on Tasco's sale of Celestron--Tasco has now filed for bankruptcy, but Celestron has been purchased by a consortium, including the original owner. Ken visited our Powhatan observing site last Sat. and had a great night--he was able to see the North American nebula through his telescope (with averted vision). Ken also announced that RAS will be able to meet in the IMAX, where we meet now, for the next year.

• Roger Rigby showed us his Earth Orbiting Observer Certificate, #007. Hmm...and this also makes him a spy for the Queen?

Observing – 

• SMV Skywatch – Gary Cowardin had a good group, about 75 people--it was a little hazy, but they were able to view Jupiter and Venus with no problem.

• Malvern Hill – Joe Hetmanski reported that no sessions have been held since the last meeting, the next viewing session is scheduled for Aug. 9 and 10.

• Powhatan – No report.

• Spruce Knob – Eric Shelton revisited this West Va. state park last Sat., and it was magnificent. This park is 4,500 feet high, so it also gets quite cold, even in July!

Education/skywatches --

• We have a couple of skywatches planned for August--Aug. 9 and 10 at Malvern Hill, Clover Hill on the 13th, Three Lakes Nature Center on the 15th, and the SMV skywatch on the 16th. If you'd like to assist, contact Jim Petty, jimhp@hotmail.com.

• The Perseids meteor Shower will peak the night of the 10th--and the moon will not be interfering, as it sets early.

• The next big star party is upon us--Stellafane, at Breezy Hill in Springfield, VT, Aug. 9. You can get more information at http://www.stellafane.com.

Observatory --

• John Raymond has scheduled the next training session for July 20. He is also starting to inventory the items we keep in the observatory. John also brought in the club telescope, a Coulter 13 inch. He has researched realumiizing the mirror, and has found a place in Florida that can do it for about $130.

Grace Suttle welcomed our visitors, David Hultstrom, David Bell, and Mary Alice Seemeyer. Welcome, and we hope you'll soon become members!

Eric Shelton gave the main presentation, on collimating a telescope. By nature, this process deals with Newtonian telescopes, of course. All optics must be aligned on the same axis. The question is: how good is good enough? The formula for a diffraction limited field diameter = .0007 X f cubed, where f is the focal length of the telescope. So, the smaller f is, the more critical the alignment has to be.

The steps are:

1. Center the mirror in the tube

2. Adjust the tilt of the mirror.

3. The focuser must be square with the tube.

4. Adjust the diagonal.

5. The secondary should be able rotate and tilt.

Some of the tools that Eric recommends are: a sight tube, with crosshairs, a Cheshire eyepiece with a 45% mirror, and an autocollimator with a perpendicular mirror. A laser collimator is also useful.

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