February 2016

Financials:

Jan 1 2016: $1881.34

$60 in renewals and 1 new membership

-$12 mailing and postage costs reimbursed to Jim

Ending balance Jan 31 2016: $1929.34

34 people in attendance tonight. We had a number of visitors, some student-age.

Larry Gillam is a returning member.

Visitor in attendance: Richard Brady, president of Tulsa Astronomy Club

Steve told us about a recent trip he’d made to Los Angeles to attend a lecture by Neil Tyson at the Palladium, which Neil gives every year.

When Neil was 9 years old he went to the Hayden Planetarium which got him interested in astronomy. He went to Cornell University at the time Carl Sagan was there. At the time he was applying to Cornell he got a letter from Carl Sagan inviting him to go for a tour. Carl met him at the bus stop, gave him his tour, visited with him a good part of the day, and gave him an autographed copy of one of his books.

When Neil redid Cosmos he repeated some of Carl Sagan’s words from the original documentary. Carl Sagan’s widow produced it.

Neil said that in the movie Titanic, the way they depicted the sky was wrong. He edited the movie.

Daryl’s update:

Next month he will present on Stellarium

He showed an image taken Jan 27 at 5:30 of the 5 classical planets lined up. He used his new fish-eye lens with a 160 degree field of view.

The 5 classical planets (Mercury, Venus, Mars, Saturn, Jupiter) will all stay visible until Feb. 20.

He showed images taken at Hula Lake with Auriga, Orion, Pegasus, Taurus, Andromeda, Vega, Lyra, Cygnus, Cassiopeia, the M31 Andromeda galaxy, and the Milky Way. He even had a movie!

Daryl gets a newsletter called orion.com.

Main presentation: Rick and Abigail on building a DYI inexpensive astrophotography tracking mount, which he termed “super simple” for those who have good basic skills with hand tools.

Astrophotography is blend of science, tech and art and it can be hard to wade through the science and tech to get to the art.

The idea of a tracking mount is to hold your equipment still and compensate for the earth’s rotation on its axis, causing the starts to shift.

The “barn door” family of tracking mounts was first started in 1972. Later versions of the mounts were developed to help with right angle tracking problems.

Tracking errors with tracking mounts are cumulative. Accuracy depends on how accurate you build your mount and how accurate your notation is, among other factors.

A wide angle is 1 X zoom—5-10 seconds

Normal is 2 X zoom—2-5 seconds

Rick and Abigail demonstrated how to do the final assembly of a tracking mount, with the necessary parts pre-cut. He used a 3/8 inch dowel, taped on each side, carved to be curved, and sanded. Accuracy of the one he made would be ½ mm. He used thin superglue to attach parts together. Piano hinges from Lowe’s are good for tracking mount construction as are cabinet hardware from Lowes’.

These kinds of mounts can be hand-operated (resetting by hand), or you can use an electric motor and then reset by hand. The hand operation (or use of electric motor) is what compensates for the movement of the stars in the pictures you take, so you can get clearer pictures.

You can search on the internet for barn door trackers. For example, a search for Barn door tracker astrophotography gives quite a few results.

Once assembled, you align your tracker on the North Star.

Rick showed images of stacked Orion Nebula pictures and the Milky Way, from Cassiopeia to Orion.