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The OBSERVER the Newsletter of the Twin City Amateur Astronomers, Inc The OBSERVER The Newsletter of the Twin City Amateur Astronomers, Inc. June 2001 Volume 26, Number 6 TCAA News — Sandy McNamara In This Issue: STRONOMY DAY, as you may mirror grinding, and Mike Rogers for have heard by now, was a rousing operating the C14 in the observatory Asuccess at Eastland Mall and while the rest of us were too busy han- especially at Sugar Grove Observatory dling the unexpected crowd to give him • TCAA News..............................1 (SGO), with over 100 visitors showing up any assistance. Public Observing Sessions, Saturday evening. SGO Updates, and More!.......... I can’t thank POS sessions are everyone who taking off at SGO showed up with as people discover • TCAA Calendar ........................1 display materials, our monthly pre- Use our calendar to mark setup/takedown sentations there. If your calendar. help, or just moral you can spare two support but if you hours on these Sat- came, even for a urday evenings, • Reports from the Field............2 little while, know your help is des- A fun picnic, a quasi-clear that it was greatly perately needed. MOOS, and a perfect POS appreciated! A You don’t need a — life is grand! special thanks to telescope or any radio host Jim knowledge of the Brown for emceeing the quiz show, Joe night sky although extra telescopes are • Variable Stars II........................3 DeHoff for wooing passers-by with his continued on next page More on stars that just can’t make up their minds! Don’t Observe Naked! • Astronomaire Script................5 See pp. 8-9 to order TCAA Garb Missed the quiz show? Too bad, but now you can read the script. TCAA Calendar • TCAA Garb Order Form ..........8 Monday, 2 July, 7:30 - 9:00 PM, Barnes and Noble Cafe If you’re observing without TCAA Reading Group. Selection: TBD TCAA Garb, you’re observing naked! 14-15 July, 2001, St. Paul, MN Universe 2001 (See www.aspsky.org for details) • Galactic Clusters...................10 15-20 July, 2001, Merrit Reservoir, NE How to find the ultimate Nebraska Star Party (See NebraskaStarParty.org for details) “wow!” objects. Saturday, 21 July, 2001, Sundown, SGO Members Only Observing Session (MOOS). • Welcome Mat..........................12 Saturday, 26 July, 9:00- 11:30 PM, Sugar Grove Observatory Public Observing Session. Coordinator: TBA 2 The Observer The Newsletter of the TCAA, Inc. The Observer is a monthly publication of the Twin City Amateur Astronomers, Inc., a non- continued from previous page profit organization of amateur astronomers interested in studying astronomy and sharing always welcome in the viewing field. new eyepieces have arrived for use with their hobby with the public. Assistance is needed for welcoming visi- it. While the dec motor still needs a little tors, directing them from the parking area work, the telescope is being used by sev- TCAA Officers to the observatory building, lighting the eral members for private viewing as well path over the still somewhat uneven as the POS. The computer station is up ground, answering questions about and running with GUIDE installed; if you President Sandy McNamara 309-379-2751 TCAA, SGNC, and SGO (or directing have any astronomy related programs you [email protected] them to those who can), etc. would like to donate, please contact me. Vice-president Brian Barling We have also had some interest expressed 309-452-7507 SGO construction is still progressing. by some benefactors that may result with [email protected] The Funks Grove Association and Sugar a CCD system donated in the future. 3rd Director Jim Baker Grove Nature Center (SGNC) have cut 309-829-1581 the siding for the one uncovered corner of KEY HOLDER training at SGO for pri- [email protected] the building, stained it, and stacked it next vate use of the C14 and other equipment 4th Director Duane Yockey to SGO. As soon as our construction in the building is progressing with 6 peo- 309-452-3936 [email protected] foreman (Dan) returns from vacation the ple (counting the teachers) now complet- 5th Director Dan Miller first week in July, we will be asking for ing the 1-hr session. If you would like to 309-473-3465 volunteers to assist in nailing it in place. have the training, please contact any [email protected] SGNC will be pouring a few concrete board member for information. There is a Treasurer Duane Yockey projects in the next month; at that time, $10 key holder fee to cover SGO expens- 309-452-3936 they have also offered to install a side- es. [email protected] walk from the parking lot to the SGO Secretary Michael Rogers building for us. The C14 has had its polar 309-828-8655 alignment roughly corrected and three [email protected] Property Manager Sandy McNamara 309-379-2751 [email protected] Reports from the Field — Observer Staff The Observer Staff Editors Michael Rogers NDER ALMOST perfect summer A week later, on 23 June, a much larger Jean Memken skies, a small band of TCAA group gathered at our public observing Umembers gathered in the new Pic- session. In spite of almost no publicity, a nic Shelter at the Sugar Grove Nature crowd of at least 75 gathered at numerous Editorial Correspondence: Center to partake of food and fellowship telescopes to savor the early summer con- The OBSERVER Editors at the annual picnic. In attendance were stellations. The weather, and even the 2206 Case Drive Sandy McNamara, Brian Barling, Al moon was perfect. Clouds that had blan- Bloomington, IL 61701 Timke, Jay Freeman, Kaila Walstrom and keted the area during the day dissipated as family, and the Memken-Rogers clan. sunset approached; and the moon dutiful- Articles, ads, etc., are due by the 1st weekend After a generous potluck meal, the atten- ly set just as darkness fell, giving us of each month. Items may be e-mailed to: dees engaged in some lively discussions, something to show the visitors until astro- [email protected], or mostly while sitting around the SGO, nomical twilight. [email protected] waiting for night to arrive. Upon dusk, Dues those who remained (Sandy, Al, Brian, Thanks to all the TCAAers who showed Kaila and Kent, Michael and Jay) had a up with telescopes and kept the crowds $25.00 per household, per year from becoming too long. And if you $15.00 for members over 60 short observing session — cut short by $12.00 for newsletter only clouds — during which the telescope in weren’t among those this month, well, $ 1.25 for a single newsletter copy the SGO performed quite well. In all, it there’s always July, and August, and... was a great beginning of what promises to be a terrific observing season this sum- mer. 3 Beginner’s Corner Variable Stars II — Michael P. Rogers HEN WE last left our hero and cosmos-sized tape measure. (Perhaps if Unfortunately, this is only useful for near- heroine, they were trapped on a there is one on Proxima Centauri, but the by stars, because those are the only stars Wprecipice fending off a horde shipping costs are horrendous). for which q is large enough to be accu- of angry..., no wait a moment, wrong rately measured. To keep things in per- story. But this is a sequel. What follows To see how this equation helps us gauge spective, the entire galaxy is about will make much more sense if you have the size of the universe, let us first ponder 100,000 light years across. The most dis- already read Variable Stars I (in last how we measure nearby objects — nearby tant star that we can measure by this month’s issue, or on the web site). in a relative term. In his preface to A Brief History of Time, Here is a fun exercise you Stephen Hawking jokes about including can do at home. Extend your equations in popular writing, explaining arm, raise your index finger, that each equation would reduce his audi- and close one eye. Pay ence by a half. So it is with great trepida- attention both to your finger, tion that I present this equation and to the background. Now close one eye and open the other; repeat several times. As you do this, you will see your finger appear to jump from one position to another relative to the background. This phenomenon, the appar- ent change in position of a where nearby object with respect to a more distant background, m = apparent magnitude, is known as parallax. M = absolute magnitude, 5 = a digit between 4 and 6, and This same principle is funda- d = distance in parsecs (a parsec, you will mental to measuring nearby recall, is approximately 3.26 light years). stars. Obviously the stars are much, much further away, We will spare you the derivation, which but fortunately the two posi- you may find in any first year astronomy tions from which we view text. Its presence there correctly implies are much, much further apart two points: first, as equations go, it is not than your eyes! particularly complicated; and second, it is absolutely critical, because it lets us get Consider the illustration at closer to answering the fundamental right. Astronomers can determine the method is roughly 1630 light years (see poser: angle q, and by definition the distance http://redshift.stanford.edu/P15/PS2_ans/ between position 1 and the Sun is exactly PS2_ans.html for the details of this calcu- How Big Is The Universe? 1 AU (Astronomical Unit). You will lation). undoubtedly recall from high school st Amazingly, at the beginning of the 21 trigonometry that the the tangent of q is So, at first blush, parallax is not particu- century, we still cannot definitively “opposite over adjacent”, i.e., 1AU/D.
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