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. larly useful: it can only get us a tiny frac- answer what must surely be the “first” Since q is exceedingly small, we can rea- tion of the way across our own galaxy, question in astronomy. In defense of sonably approximate tangent of q by q. and be of no help whatsoever with other those astronomers who have toiled over i.e., q = 1/D, or to put it another way, D = galaxies (Andromeda, for instance, is 25 the centuries and still have not answered 1/q. In short, given the angle, we can million light years away). this completely, you cannot merely head determine the distance. down to the local Menard’s and buy a continued on next page 4
continued from previous page
However, parallax does help, indirectly, the same distance. Hence, the even with more distant objects. To see longer the period, the brighter the how, first recall Cepheids — variable star in absolute magnitude. Now if stars that, over a period of several days, only we knew what the absolute show a periodic rise and fall in magni- magnitude of one star was... but we tude. This repeats with almost clocklike do! There are some cepheids close precision, and has been known for cen- enough to measure using parallax; turies. so we know their distances, and thence absolute magnitudes, as well Next. it is my pleasure to introduce one of as their periods. That is enough to the unsung astronomers of the 20th centu- establish the Period-Luminosity for ry — Henrietta Leavitt — a rather unpre- Cepheid variables: by measuring possessing looking woman who discov- their periods, we determine their ered that Cepheids had another, and absolute magnitude M; and then extremely valuable, secret. Leavitt was substituting in the equation above, employed at Harvard College Observato- we can determine their distance! ry. The head of the observatory, Picker- The Cepheid can be next door (although we hope not) or in the most distant galaxy — as long as we can measure its variabili- ty, we can determine its distance from Earth.
There was a slight com- plication — it turns out that there are two kinds of Cepheids — but that has been all sorted out; and Cepheids remain a fundamental tool in the astronomer’s quest to measure the size of space. Henrietta Leavitt, hard at work ing, assigned her the unenviable task of A question that must surely rank as cataloging variable stars. She studied number in the FAQ for variable photographs of the Magellanic Clouds, stars is, why do they vary? What is two small companion galaxies that orbit the underlying mechanism that our own (and unfortunately can be only causes these stars to brighten and seen in the southern hemisphere). Study- dim, in some cases with almost ing these, Leavitt found 1,777 new vari- machine-like precision? able stars, including 20 Cepheids. If you want to know, stay tuned for Graphing the Magellanic Cloud cepheids, the next installment! Leavitt found that the longer the period (that is, between troughs), the brighter the star (in apparent magnitude). And of course, since these stars were all in the same cloud, they were at approximately The Lesser and Greater Magellanic Clouds 5
Who Wants To Be An Astronomaire? — Jim Swindler, Michael P. Rogers
STRONOMY DAY has come and light is called a: represented by a constellation: gone, and still I have people a. deflector Aapproach me on the street, con- b. refractor a. Hare gratulating Jim and myself for our clever c. parabaloid b. Crab script. OK, no, not really; but since so d. reflector c. Flying Horse few people actually *heard* the show — d. Flying Squirrel the majority of TCAAers present were for 5. The person who *first* proposed that some bizarre reason more concerned that the Earth orbited around the sun was: 12. Which of the following instruments telescopes and computers didn’t suddenly a. Aristarchus (musical and/or optical) are not represent- sprout legs — as a public service here is b. Plato ed by a constellation: the script of WWTBAA. c. Copernicus d. Gulducat a. Flute Welcome to Who Wants to be an b. Triangle Astronomaire, the show that promises you 6. Stars glow because of: c. Harp the sun, the moon, and the stars (and a. fission d. Microscope delivers!). The rules are roughly the same b. fishin’ as those of that famous television show, c. fuscia 13. Which of the following is not a except...our prizes are much classier — d. fusion galaxy? TCAA Garb, much sought after and never sold in stores — and a year’s membership 7. The brightest star visible in the north- a. Andromeda in a really great astronomy club. ern hemisphere is: b. Cepheus a. spica c. Sombrero You have 3 lifelines, and can ask the b. mizar d. Milky Way audience — although since many of these c. serius people want the TCAA Garb for them- d. kidding 14. Pluto’s Moon is called: selves, don’t believe them! 8. The planets with detectable rings are: a. Sharon 1. The telescope was invented by: b. Sharin’ a. Venus, Jupiter, Saturn, Pluto c. Charon a. Edwin Hubble b. Earth, Mars, Jupiter, Saturn d. Chevron b. Galileo Galilei c. Jupiter, Saturn, Uranus, Neptune c. Jean Luc Picard, during that really great d. Saturn, Uranus, Neptune, Pluto 15. The cloud from which comets origi- episode when he goes back in time with nate is called the: Q... 9. Objects that are moving away from us d. Clyde Tombaugh at a high rate of speed: a. Jan Cloud b. Ooort Cloud 2. The Milky Way consists of: a. appear bluer than normal c. ProctorGamble Cloud (hey, they make b. appear bluer than blue (to be sung) Comet) a. Milk c. appear redder than normal d. Lowell Cloud b. Whey d. appear more paisley than usual c. A hundred billion or so stars (give or take a few 10’s of billions) 10. The number of stars visible to the d. Dust naked eye on a dark, moonless, cloudless night are, approximately, 3. The farthest planet from the sun is: Game II (slightly harder, and if we a. Venus a. 500 need it...) b. Earth b. 5,000 c. Saturn c. 50,000 -3. Auroras on Earth are caused by d. California d. oodles and oodles
4. A telescope that uses mirrors to gather 11. Which of the following animal is not continued on next page 6
continued from previous page a. General Motors d. Obi-Wan Kenobi. d. The winners of Who Wants to be an b. Meteors burning up in the atmosphere Astronomaire?. c. Solar flares 6. What does equinox mean? d. Neutrinos a. The half-way point in a star’s life. b. The average distance between a -2. Who believed the Sun orbits about the planet and the sun. Who Wants To Be An Astronomaire, Earth? c. A time when days and nights are of Jr? equal length. a. Copernicus d. Equally obnoxious astronomers. 1. The five planets visible to the naked b. Galileo eye are: c. Ptolemy d. Joe Dirt 7. An “Event Horizon” goes with which a. Mercury, Venus, The Moon, Jupiter, type of astronomical body? Neptune -1. The densest stars in the universe are a. White dwarf star. b. Venus, Mars, Saturn, Uranus, Pluto a. red dwarfs b. Nebula. c. Mercury, Venus, Mars, Jupiter, Saturn b. black holes c. Black Hole. d. Jupiter, Saturn, Uranus, Naboo, Pluto c. supernovae d. A Hollywood starlet. d. currently living in Hollywood 2. Astronomers mainly use which of the 8. What is a solar prominence? following instruments? 1. How wide is the Milky Way Galaxy? a. An active region of sun spots. a. About 100,000 light years across b. A relatively cool area on the sun’s a. Televisions b. Exactly one parsec. surface. b. Telescopes c. About 5 light years across. c. A huge burst of fiery hydrogen gas c. Teletubbies d. About 5 heavy years across. from the sun’s photosphere. d. Tell, William d. A really good suntan. 2. What is a cloud of interstellar gas and 3. A light year is a measure of: dust called? 9. Where is our spiral arm of the galaxy? a. A pulsar. a. The Cygnus arm. a. distance b. A nebula. b. The Perseus arm. b. time c. A black hole. c. The Norma arm. c. color d. A bad omen. d. The Bloomington-Normal arm. d. weight
3. Comets are composed of...? 10. When a star collapses into a singular- 4. Which of the following cannot travel a. Ice and dust particles. ity, what is created? through space: b. Molten rock. a. A quasar. c. Solid rock, like an asteroid. b. A black hole. a. Light d. Green cheese. c. A neutron star. b. Sound d. The Land of Oz. c. Radio 4. Which astronomical distance is the d. Bad news longest? 11. What does the famous Hertzspring- a. An astronomical unit. Russell (H-R) diagram classify? 5. A solar eclipse happens because: b. A parsec. a. Galaxies. c. A light year. b. Stars. a. The Sun is covered by Earth’s Shadow d. How far a cow has to jump to get c. Comets. b. The Earth is covered by the Sun’s over the moon. d. The carrying capacity of rental cars. Shadow c. The moon blocks out the Sun 5. Who first used the telescope to view 12. What are the brightest known objects d. Clouds blot out the Sun the planets? in the universe? a. Hubble. a. Quasars. 6. Which of the following are not alterna- b. Newton. b. Galaxies. tive names for the Big Dipper: c. Galileo. c. Pulsars. 7
continued from previous page a. Ursa Major b. The Plough 12. Planets orbit the Sun in: c. Big Bear d. Big Bertha a. a circle b. a parabola 7. A rock that falls to Earth from outer c. an ellipse space is called: d. an octagon a. a comet b. a meteor 13. Asteroids are chunks of rock floating c. a meteorite between d. a meteorologist a. Mars and Jupiter 8. Mars’ moons are called: b. Jupiter and Saturn c. Earth and Mars a. Io and Europa d. Hither and yon b. Phobos and Deimos c. Barnes and Noble 14. The most expensive telescope in his- d. Ganymede and Callisto tory, the Hubble Space Telescope, suf- fered from initial problems because it’s 9. The first man on the moon was: designers: a. Louis Armstrong a. neglected to take temperature into b. Neil Young account c. Neil Armstrong b. forgot the film d. Captain Ann Tenille c. misconfigured the primary mirror d. ... what do you mean initial problems? 10. The hottest stars are: The HST was and is perfect! a. red 15. What are the brightest known objects b. blue in the universe? c. yellow a. Quasars. d. green b. Galaxies. c. Pulsars. d. The winners of Who Wants to be an 11. Which of the following are *not* Astronomaire?. constellations: a. the Great Bear b. Leo the Lion c. Pegasus the Flying Horse d. Rocky the Flying Squirrel
Imagine your Ad Here!
Contact The Observer sales team (309-828-8655) for details. 8
TCAA Garb Order Form
Instructions: 1. Read the article on the next page. None of this will make any sense until you have done so. 2. Boy you’re a fast reader! 3. Fill out this form, and return it, along with a check, to:
Michael Rogers 2206 Case Drive Bloomington, IL 61701-1474
Make your check payable to me. I promise not to abscond with the funds to my secret hideaway in the Caribbean. Oh drat, so much for secrecy...
4. T-shirts are available in Black, Red, Royal (blue), Burgundy, Evergreen, Forest, Navy, Purple, Earth (dark brown), Moss (dark green with yellow), Shale (dark gray), and Denim (dark blue, lighter than navy); Sweatshirts are available in all of the preceding col- ors except Earth, Moss, Shale, and Denim; Polo shirts are available in all of the preceding colors except Evergreen, Earth, Moss, Shale, and Denim
Name: ______
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T-Shirts & More The T-Shirt Back — Michael P. Rogers
S MENTIONED elsewhere in the last issue, we inadvertently gave Aaway too many t-shirts during the WWTBAA contest. So, in the interests of accommodating those people who had ordered but were stiffed, not to mention the many new members who have joined since the club last produced t-shirts and sweatshirts, we present this splendid opportunity in sartorial splendor — a chance to order TCAA Garb!
Our customized clothing vendor of choice, C Tees, offers a very nice price on t-shirts, polo shirts, and sweatshirts: Item Size Cost T-shirt SM-Xl $10.55 XX $11.85 XXX $12.70
Polo Shirts SM-XL $16.00 XX $17.40 XXX $18.60
Sweatshirt SM-XL $18.20 XX $18.90 XXX $19.15
Prices include a silk screen of the TCAA logo (the web site version) over the left breast on the front, and a museum-quality transfer of the solar system (superimposed The T-Shirt Front over a spiral galaxy) on the back. The transfer probably looks best on black, but any dark color should do.
If you are interested in the above, then all you need to do is return the enclosed order form, with a check payable to me; I’ll put all the checks together and pay CTees.
The deadline for ordering is 30 June, 2001. We will need a minimum of 12 orders, otherwise I’ll just return the checks.
Questions: [email protected]. 10
Observing Globular Clusters — Sandy McNamara
ach season has its premier type of ular cluster deep sky object to observe. would have little EAutumn displays many planetary of our concerns nebulas to hunt for, winter abounds with about dark adap- bright open clusters, spring is galaxy sea- tation — and dif- son, and summer is the best time to hunt ficulty finding for globular clusters (GC). Why are GCs the dim galaxies I best in the summer? During our sum- personally enjoy mers, the southern view is inward toward challenging the center of our galaxy (located beyond myself with! the stars of Sagittarius). Globular star clusters are groups of hundreds of thou- While less than sands of stars bound together by gravity 200 GC are in a densely-packed spherical swarm of included in the stars orbiting about the center of our 7000+ objects in Milky Way galaxy (other galaxies have the New General globular clusters, too). They seem to be Catalog of deep concentrated near the Milky Way, both sky objects north and south of the plane of our (NGC), over 1/4 galaxy; there are few right at the center of (29 of 110) of the the sweep of the Milky Way due to their objects on placement around the outside edges of our Messier’s list of galaxy’s hub. GC involve hundreds of “non-comets” are thousands (and in the case of the largest GC, which may The Incomparable M13 clusters, a million or more) stars. They give you some idea of what these objects difficult to decide whether an object was a contain some of the oldest stars in the look like through smaller telescopes. I’ve small, tightly packed open cluster or a galaxy and may have been one of the first included the GC class in parenthesis after very loose GC and several NGC objects parts of the galaxy to form. In contrast, each to perhaps help in what you should have been reclassified over the years. open clusters (sometimes referred to as expect to see. My early notes, using an M71 in Sagitta has been called both an “galactic clusters”) are usually scattered 80mm refractor, describe many GC (in open and a globular cluster but is now along the spiral arms of our galaxy and highly scientific terminology
continued from previous page (class V, VI, VII): packed close enough to Messier Summer Globular Clusters be impressive yet loose enough to resolve many individual stars in the cluster. NGC AKA CON RA DEC Size Mag Class 5272 M3 CVn 13h 42m +28d 23m 10’ 6.4 VI For completeness, our object list this 5904 M5 Ser 15h 18m +02d 05m 13’ 6.2 V month includes all of the spring and sum- 6093 M80 Sco 16h 17m -22d 59m 5’ 7.5 I mer Messier GC [and as an added, web- 6121 M4 Sco 16h 24m -26d 31m 14’ 6.2 IX site bonus, the Herschel 400 list for those 6171 M107 Oph 16h 33m +13d 03m 10’ 8.1 X of you who prefer a challenge]. Obvious- 6205 M13 Her 16h 42m +36d 27m 10’ 5.7 V ly, I don’t have room here to direct you to 6218 M12 Oph 16h 47m -01d 57m 9’ 6.6 IX all of them; however, the selections 6254 M10 Oph 16h 57m -04d 07m 8’ 6.7 VII described below will give you a taste of 6266 M62 Oph 17h 01m -30d 07m 5’ 6.6 IV the various types that can be found. After 6273 M19 Oph 17h 03m -26d 15m 4’ 6.6 VII you’ve become accustomed to how these 6341 M92 Her 17h 17m +43d 09m 9’ 6.3 IV fuzzies look in your telescope/binoculars, 6333 M9 Oph 17h 19m -18d 31m 9’ 7.6 VIII grab your favorite star atlas and have fun 6402 M14 Oph 17h 38m -03d 15m 12’ 7.6 VIII finding the rest of the GC on the list :-). 6626 M28 Sgr 18h 25m -24d 52m 5’ 7.4 IV 6637 M69 Sgr 18h 31m -32d 21m 4’ 7.6 V While M13 (V) may be the most famous 6656 M22 Sgr 18h 36m -23d 55m 18’ 5.9 VII GC, in my personal opinion, the best GC 6681 M70 Sgr 18h 43m -31d 18m 4’ 8.0 V in the summer skies has to be M22 (VII) 6715 M54 Sgr 18h 55m -30d 28m 3’ 7.3 II in Sagittarius. This sparkling beauty is 6779 M56 Lyr 19h 17m +30d 10m 2’ 8.2 X easily located just over 2 degrees NE of 6809 M55 Sgr 19h 40m -30d 56m 10’ 7.4 IX gamma Sgr (the top star of the teapot’s 6838 M71 Sge 19h 54m +18d 47m 6’ 8.3 ??? “lid”). This cluster seems to have an 6864 M75 Sgr 20h 06m -21d 55m 3’ 8.5 I almost 3D look in any size of telescope (II) which may be found halfway between oval elongation? Does the brighter core but increasing aperture and magnification Antares and beta SCO. Those of you look centered or slightly off to one side? make the effect more apparent. Compare wishing more of a challenge can examine GC abound in Ophiuchus and I enjoy it with the less impressive M28 (IV), NGC 6144 (XI), just 1/2 d NW of “two for one” specials. For example, look found 1d NW of gamma Sgr and the even Antares. Make sure Antares is out of first for M9 (VIII), appearing 2 d E and 3 smaller NGC 6638 (VI) just 1/2 d E of your field of view and see if you can d S of eta OPH as a “fuzzy star” in a find- gamma Sgr to see how size and magni- resolve many stars in erscope; a 6-in telescope should begin to tude can influence this very loose but resolve stars around its edges. Half as big being able to not overly bright and half as bright, NGC 6356 (II) lies sl observe and resolve GC. over 1 d NE of M9; while its soft fuzzy GC, even though glow was easily found, I wasn’t able to they may be of simi- M19 in OPH is one resolve it in an 8-in telescope. The even lar star concentra- of the few GC that is fainter NGC 6342 (IV) sl over 1 d SE of tions. not circular in M9 makes a nice challenge for those of appearance (Omega you bored (!) with Messiers. Another easily locat- Centauri, visible ed GC is M4 (IX), sl from more southerly If you prefer to wait until Oph/Sco/Sgr over 1 degree W of locations, is anoth- are higher in the summer skies, check out bright Antares in er). To locate it, M92 (IV), 6 degrees N of pi HER (the NE Scorpius; it is easily sweep 7.5 degrees E corner of the “keystone”). Overshadowed visible as a round from bright Antares by its more famous neighbor, M13 (V), fuzzy spot in binoc- in Scorpius (or 2.5 d M92 is a fine GC in its own right and ulars or finderscope. The Fabulous M4 E and sl N of bril- begins to resolve into stars with as little as Compare its loose, liant Mars in this 60x. easily resolved structure with that of the summer’s sky). Can you detect the N-S smaller, more tightly concentrated M80 12
The Welcome Mat
Each cherub, still sleepy from a late-night observing session, is dueling to wake up the other, while they welcome our newest members. A warm end-of-June welcome to...
Mary Kay Herrmann Bloomington
Thomas & Lisa Banasik Bloomington
The OBSERVER The Newsletter of the Twin City Amateur Astronomers, Inc.
Michael Rogers & Jean Memken, Editors 2206 Case Drive Bloomington, IL 61701
Dues Due? The Dues Blues If you see a check in the box above, it means your dues are due. To retain membership -- and with a new observato- ry, why quit now??? -- please send $25 to our esteemed treasurer:
Duane Yockey 508 Normal Avenue Normal, IL, 61761
As always, thank you for your support!!