Guided tours - a public program example

Guided tours are shaped to the times and specific wants and needs of the individuals. During the tour participants pack in quite a few experiences - and hear a lot of facts - in a very short time. Because of this I assumememories start toblur together, so I follow up such a tour by an email with a note such as the one that follows. While what folows was written for one participant covering one tour, reading it you can get a glimpse of what a guided tour experience is like. However, as the automobile manufacturers like to say, "your milage may vary." ;-)

Program: Guided Tour
First participant: single adult, October 20, 2005

Instruments used:

15-inch Obsession, a Newtonian reflector on a Dobsonian mount with ServoCat providing tracking and ArgoNavis as the computer brain. Used Denkmeir Binoviewer with Power Switch and Denkmeir 21mm eyepieces. This is a top of the line reflector, custom made in Wisconsin. Few amateur observatories, especially on the East Coast, have larger instruments. The most popular-sized telescopes for serious amateurs is 8-inches and such a scope has about one-fourth the light-gathering area as this.

6-inch SkyWatcher, a traditional refractor on a home-made Alt-Az mount much like a Dobsonian. Used several eyepieces as well as a 2X Barlow lens to double their power. This is an inexpensive, but medium quality, refractor made in China. Rarely will you encounter a refracting telescope larger than this. Most are in the three-to-five inch range.

Objects viewed:

Messier 31 – M31 –The Andromeda Galaxy – Our largest “neighbor” in the “local group” of galaxies, this blurry spot in the constellation Andromeda is really 300 billion stars about 2.5 million light years from us. Nearby is M32, a “fuzzy star” which is really a companion galaxy, but much smaller. M31 is about 150,000 light years across – M32 about 2,000.

M11 – the “Wild Duck” cluster – An open star cluster and part of our own Milky Way galaxy, it is about 6,000 light years away and contains more than 1,000 stars, most of which are hot, young, and thus blue. This cluster is estimated to be 100 million years old – which is young when you consider our Sun is about 5 billion years old.

M15 – a globular cluster (as opposed to “open”) – Globulars are large, highly concentrated collections of very old stars that tend to hang around the outer fringes of our Galaxy. They are part of the galaxy, but usually quite distant. There are a few hundred thousand stars here, packed into a ball about 125 light years in diameter about 40,00 light years away.

M27 – the “Dumbell Nebula” - A planetary nebula which is a shell of thin, cold gas expanding out from a central star which has collapsed near the end of its life. While this star is to faint to see, it provides the energy that makes this cloud of gas glow. This one is about 1,000 light years from us, two light years in diameter, and the event that started it growing took place about 50,000 years ago.

M57 – the “Ring Nebula” – This is a second planetary that appears much smaller to us and has the more characteristic smoke-ring shape of other planetaries. It’s exact size and distance are not accurately known, but an educated estimate is one light year across and about 2,000 light years away. Under very dark, clear skies folks using a 15-inch telescope say they have seen the central star. It’s very difficult to glimpse. (This was viewed first in the 15-inch, then later found by you using the 6-inch.)

Alpha Lyra – Vega – This brilliant, blue-white star is magnitude 0 (the brightest star on a fall night) and about 25-light-years from us. (This is the first object you found using the 6-inch.)

Epsilon Lyra – The Double-double – This appears to be one star to the naked eye, but even in the finder we see it as a widely-split double. These two stars are about 200 light years from us and on a good night with steady air and high power each proves to be two stars, thus the popular name. This is a true multiple-star system where all four stars are connected to one another by gravity.

Mars – This planet is best viewed every two years when for a few months it’s relatively close to us. But some years it’s closer than others and this is the closest it will be until 2018. Here’s a map of the part of Mars exposed to us as we were viewing.

Beta Cygni – Albireo – A double star you identified as “blue and gold.” All stars show color, but it is usually hard for people to see. When you see two stars of contrasting colors this close, however, it’s easier.

The moon – we used filters that let through only 13% of the light. The moon was waning and about 18.5 days old so the terminator – the line between dark and light – was near the Sea of Tranquility and most of the craters we were seeing were in the rough, southern highlands.