Hamilton Amateur

March 1997 Volume 4 Issue 5 Saga of the Winter

t seems that when one the road awaiting that time. My trusty decides to take a trip After a short stay in navigator, in less than half an hour, has somewhere, the elements Nashville, where we took part in the gotten a sunburn on her right arm. The join forces to either try to discourage, or taping of a country and western show, is brilliant, and there is not a cloud speed one on ones way. In our case, it we made a beeline for Florida. Here in the sky. At this point, the the weather is warm. The trailer is temperature is 28C. Eat your hearts out now free from ice and snow, and we you northerners! “We can see that it is going are no longer a curiosity. to be an 's dream. Finally, we are moving. At the It is beautifully warm, 73 F, We are now just south of the gate we show our passes and proceed to and the skies are clear” site of the Winter Star Party. We are find a good setup site. We park directly the 65th vehicle in line to get in. across from where we were last year. A sped us on our way. Admission time is set for 12 noon, so good spot. After an hour, we have we are all parked on the shoulder of (Continued on page 5) It was cold and snowy, but the 401 was delightfully clear, so we made excellent progress into the United States. There, the ele ments fought Mirrors on the Move against us. At 1700 hours we decided to efractors and Newtonian- much closer than can refractors or head for some warm sheltered spot like type reflectors have fixed Newtonian scopes. In addition to a motel. Ah. Good move on our part. primary objectives and focus viewing objects at infinity, compact by having the eyepiece move back and SCTs can be used to exa mine and Bowling Green, Ohio. The temperature forth. Cassegrain-type reflectors, photograph wildlife or close-by objects is hovering at -5C and the sky turns including the ever popular Schmidt- a matter of only a few meters away. clear. Ah, there's the Dipper. It does not Cassegrain, have fixed eyepieces and seem to be oriented the same as when it achieve focusing by having the primary The secret lies in the is seen in Rockwood. mirror move up and down the optical amplifying effect (convex shape) of the axis. secondary mirror. A very slight change So we are on our way again.... What's in the separation of the two mirrors is that clunk sound? Aaah a big chunk of It is difficult to machine to enough to produce an enormous change ice and snow fell off the trailer, must be close enough tolerances so that the in the focus. A typical 8 inch f/10 (80" getting warmer. Hark, what is that mirror does not tilt as it moves back and focal length) SCT can focus on objects sound I hear? No it couldn't be, but it is. forth, causing some image shift when as close as 8m (~25 feet) away. There they are, a least a hundred robins focusing. It has to be more expensive to Calculations show that to do the same, a on the lawn in front of us, just singing produce than just fastening a rack-and- refractor or Newtonian reflector with their little hearts out. We must be pinion focuser to the end of an SCT. the same 80" focal length would have to getting in to warmer climes, that Why, then, is it done this way? move the eyepiece back 69cm (~27")- a accounts for the fact that so many totally impractical possibility. people we see are wearing short sleeve The answer lies in the ability shirts, and short pants. of a such a reflector to focus on objects (Continued on page 6)

Editorial page 2 Hipparcos page 6 inside... Ask the “Expert” page 2 Digital Flashlight page 7 Comet Lottery page 3 April Night Skies page 9 Rob’serving Report page 3 Page 2 Editorial

he big news this month is comet’s tail at 140 power from their comet Hale -Bopp. On page backyard in Hamilton on March 11 and four is a finder chart for the 12. My observing conditions were not comet . I doubt that you will actually very favourable - in a neighbours have to use this chart for anything other driveway standing under their light than noting how the comet will be above the garage with the comet less vent Horizon is a publication moving through the sky in the next than 10 deg away from a street light. of the Hamilton Amateur short while. As I write this, all you have At 120X, with a 6 inch Newtonian, I Astronomers (HAA). to do is step outside and look to the was able to see what I can best describe north-west just as the first stars begin to as waves coming from the comet down The HAA is an amateur appear after sunset. The comet is the towards the horizon and then blending club dedicated to the most obvious object in that area of the into the tail which made a 90 degree promotion and enjoyment of astronomy sky. turn to the north. for people of all ages and experience Juliana Light has a very timely I hope that all of you are going to levels article, on page 3, about a talk on Hale- take every opportunity to view this Bopp that she recently attended. comet. It could be years before the next The cost of the subscription is

bright one comes along. included in the $15 individual or $20 Ann and Bill Tekatch reported family membership fee for the year. seeing a spiral/corkscrew effect in the Stewart Attlesey Event Horizon is published 10 times a year.

HAA Council Ask the “Expert” have seen pictures of the plane of our is sharply Chair Doug Welch Halley's Comet when it different to the plane of the main part of Second Chair Grant Dixon appeared in 1910, and I was the stars in our Milky Way galaxy? Is Honorary Chair Jim Winger eagerly looking forward to seeing it our solar system plane really that Secretary Patricia Baetsen when it returned in 1986. However, to different (90 degrees) to the main Treasurer Barbara Wight my great disappointment, I could hardly galactic plane? Or does it also have Education Dir. Grant Dixon see it at all, even in binoculars. Why something to do with the tilt of the earth Obs. Dir Rob Roy was there such a difference in the two on its axis? Editor Stewart Attlesey

appearances? The nature and orbit of Recorder Tracy Webb Brian Chire the comet doesn't change, does it? Membership Dir Ann Tekatch HAJA Coord Rosa Assalone Brian Chire It is a combination of factors. Not only is the plane of the solar system Councillors The comet’s orbit is relatively (the ecliptic) tilted with respect to the constant (although Jupiter’s gravity plane of the Milky Way (galactic Patricia Gassmann causes some minor changes) but the equator) but the Earth’s axis is also Alan Shinn position of the Earth relative to the tilted with respect to the ecliptic. The Bill Tekatch comet was different for the two north pole of the solar system (north appearances. In 1910 the Earth actually ecliptic pole) lies about 23.5 deg away passed through the tail of the comet from polaris in the constellation Draco (and will again in 2062) but in 1986, (18h 00m R.A.) and the North pole of Halley’s comet was quite far from the our Galaxy (north galactic pole) lies Earth at its closest approach to the Sun about 27 deg away from polaris in the (perihelion). constellation Coma Berenices (12h 51m R.A.). By the way, it is our tilt of 23.5 I have always wondered why degrees from the ecliptic that accounts the Milky Way is not horizontal to our for the seasons. Also, during the winter horizon when we look at it in the sky. In the night side of the earth is facing fact, in the summer, it appears away from the centre of the galaxy and overhead, almost 90 degrees to our during the summer the opposite is true. horizontal perspective. Is this because (Continued on page 8) Event Horizon - Hamilton Amateur Astronomers Page 3 Winning the Comet Lottery

homas Bopp, co-discoverer bill. Intrigued, they started to watch for but only got an answering machine, of Comet Hale-Bopp, spoke motion. After a while Jim thought he then he tried to call the International recently at the Ontario could detect movement. Yes, a bit, Tom Astronomical Union's Central Bureau Science Centre at a meeting of the agreed, but he wanted to wait a while but his car phone was out of range, he RASC Toronto Centre. longer. After about another fifteen said. He hoped he could send a minutes it was agreed that the object telegram from a nearby truck stop, but Tom lives in Arizona and was definitely moving. But what to do no luck there either. Confounded, he opened his talk with a series of slides of next? Another observer advised not to drove the ninety miles home. There he the Arizona night sky. He is a lifelong bother reporting anything. He had once tried another phone number, but only amateur astronomer, and his story of reported a super nova, but it had turned got the Visitors' Centre with a recording the discovery of the comet could be one out to be Venus! But Tom and Jim were telling him when visiting hours were. which many in the HAA could have sure it had moved. Not quite sure what Finally through Western Union he was told ... if they had been as lucky as to do next, they thought the best thing able to send a telegram, and with that Tom; lucky like winning the 649 lottery to do would be to report the discovery accomplished he collapsed into bed that is. to the nearby Lowell Observatory. Tom beside his wife who was thinking he attempted to contact the Observatory (Continued on page 4)

“Using a 17-inch Dobsonian, Jim had turned his attention ob’serving to M70 and offered Tom a eport view of it.” Deep Partial Lunar Eclipse Monthly In-Sights The day Tom won the comet lottery was July 22, 1995. It had begun Lying deep in the shadow of March with his friend Jim inviting him to go this month's growing excitement over · 17-3am Mars at opposition to the observing that night at a site ninety Comet Hale-Bopp is the partial eclipse Earth. miles from his home. Tom had wanted of the Moon (pun intended.) On the · 20-8:55amEST **SPRING IS to make an early start to get to the site night of March 23/24, the Moon will SPRUNG!** (equal day and night) well before dark, but various things enter the Earth's shadow and be very · 22- Hale -Bopp's closest approach delayed him including the fact that his nearly totally eclipsed. Don't ignore it, to Earth. car wouldn't start, so he had had to saving up your time for Hale-Bopp · 23- partial (92%) lunar eclipse. borrow "Dad's car," he said. It was dusk later. · Mars 4 deg. N of eclipsed Moon after all when he finally got to the site, It could prove to be a beautiful and (photo opp?) and he was mortified that he was unable spectacular event. The Moon should · 25- Hale-Bopp 5 deg. N of M31 to turn off the headlights of the car, take on a ruddy-orange hue as it nears (photo opp?) best period for night-blinding everyone as he drove up mid-eclipse. Some say that the view viewing Hale-Bopp sans Moon, to the observing site. He and his friend becomes three- dimensional in lasting until April 8. then began their observing session binoculars. I personally hope to get · 31- Hale -Bopp's closest approach looking at the usual assortment of some great photos. to the Sun. Messier and NGC objects. Using a 17- April inch Dobsonian, Jim had turned his Below are listed the times of · 3-3am Moon 4 deg. N of Jupiter. attention to M70 and offered Tom a the key phases of the eclipse. · 4&5- BCA observing nights. view of it. Jim was doing something else now, and as Tom gazed steadily at 8:41pmEST- Moon enters the faint · 5-8pm Mercury at greatest eastern M70, which is a small globular cluster penumbral portion of the Earth's elongation in the evening sky (12 in Sagittarius, he let it drift across the shadow. deg. altitude!) field of view. As it drifted, he noticed 9:58pm- Moon enters the dark umbral · 8-9pm Mercury 7 deg. to the right that a curious bright object had portion of the Earth's shadow. of thin crescent Moon. appeared to the left of the image. 11:39pm- Mid-eclipse with the Moon · 8- last date for Hale-Bopp without 92% in shadow. interference from the Moon. "Hey Jim, do you know 1:21am- Moon exits the umbral · 10-midnight Moon 0.5deg. N of anything else near M70?" he asked. Jim shadow. Aldebaran. said he didn't. They looked up their 2:38am- Moon exits the penumbral various star atlases but nothing fit the shadow. (Continued on page 7)

Event Horizon - Hamilton Amateur Astronomers Page 4 Comet Lottery ...

(Continued from page 3) exact orbit was determined. had really lost it. In closing his talk, Thomas Early on the morning of the Bopp showed slides of the comet taken 23rd, Tom was awakened by the phone from various sources ranging from the ringing. It was Dan Green from the to amateur Harvard-Smithsonian Centre for 35mm photographs and CCD images. . "Congratulations, you've Each image was amazingly different found a new comet!" Dan said. In his revealing different aspects of the comet Thomas Bopp kitchen Tom proceeded to invent a new such as close-ups of the coma (the comet dance just for the occasion. comet's nucleus is thought to be about 40km in diameter, travelling at a speed As more observations of the of about 60 km/s) to whole images of to look at M70. As he was at home comet were reported, Dan Green and the comet with its distinctive long and when he made his discovery, he had colleague Brian Marsden attempted to slender ionized gas tail and shorter and simply e-mailed his report in. (Allan compute the orbit of the new comet, but wider dust tail. The last slide, however, Hale has written a book on the even with observations from Japan no was quite different. It was a picture of a discovery called Everybody's Comet: A parallax could be measured. This meant tall ship sailing in the Caribbean on Layman's Guide to Comet Hale-Bopp.) that the comet was very far away and as which, Tom said, comet discoverers are such it must be a "monster" comet or invited to sail. It is a bit like winning The meeting also included a very peculiar indeed. Only a rough the lottery, I'd say. short talk by Peter Ceravolo who estimate of the comet's orbit was showed his amazing video "Comet possible by July, and by August they Someone in the audience Hyakutake, The Motion Picture" which had determined that the comet would asked about the comet's other was shot in Arizona, and David Levy, come into the near solar system and that discoverer, Allan Hale. How had he who lives in Arizona, gave a poetic talk perihelion was roughly predicted for discovered the comet? Allan also about comets and their discoveries. At April 1, 1997. Finally, a previously happens to live in Arizona, Tom told the conclusion, Ivan Semeniuk unnoticed image of the comet was us. His evening of observing seems to reminded everyone that the Observer's discovered on a photograph taken over have gone a lot smoother than Tom's. Handbook published annually by the two years previously in Australia. It Coincidentally, he was in his back yard RASC has instructions on how to report revealed that the comet was 9.6 a.u. that night observing known comets. a discovery on page 8. away, and with this information a more Between comets he turned his telescope

Submitted by Juliana Light, with apologies to Tom Bopp for any misinterpretation of his talk.

The finder chart on the left shows comet Hale -Bopp’s position at four day intervals starting on March 15.

Event Horizon - Hamilton Amateur Astronomers Page 5 Winter Star Party ...

(Continued from page 1) seen so clear. I try my 12mm cranked up the trailer and gotten eyepiece...awesome. I can see the Of course, we could not go all ourselves organised. At this point, our moons, I can see not only the rings, but that way to Florida and not see Hale- neighbours, two chaps from Findlay the shadow of the rings on the surface, Bopp, and see it we did, in all its Ohio, come over and introduce and get this, I can see a shadow of a splendour. We rose at 0445 hours, went themselves and give us a load of moon on the surface. Thinking I could outside and joined scores of others to grapefruit. As it is still early, I set up push it a little further, I tried Oksana's see the comet. I could see it with my my brand new 8" LX200 then go for 4.7mm Nagler. Too much power. The naked eye, and with my eyesight, if I supper. One cannot view the heavens Owl Nebula? Stupendous. It just got can do that you can imagine what a on an empty stomach. better and better as the night turned into spectacle the comet was. Through morning. Retired somewhat late, but binoculars it was awesome. We oohed Monday evening. Spectacular. utterly refreshed. So, the first day at the and aahed for at least an hour and a half We can see that it is going to be an Winter Star Party, a resounding until the dawn took it from our sight. At astronomer's dream. It is beautifully success. this time in the morning, the Big Dipper warm, 73 F, and the skies are clear. We is parallel to the horizon, actually we are all chomping at the bit to get Naturally, one does not go to could see that it was indeed circling started. On our way back to our site, we the Keys and spend the time looking at Polaris. see so many scopes pointing toward stars all the time, there are days. So the Polaris in order to get an early fix. The first day we thought we would We had ample opportunity to BIG, and I do mean Big, Dobs are all investigate the marine life here by using uncovered and ready to take on the sky. a flexible rod connected to a tether of There are so many Dobs, that they have some sort, which in turn has a device on named their area, the Valley of the the end with some enticement to invite Dobs. And rightly so. From the smallest marine life to be a part of.(We went 6 inch reflector to the behemoth 36 fishing). We were most successful in incher, and all sizes in between we are our endeavours, the final tab being: two in a telescope paradise. pelicans, one speedboat, two cowfish, two puffer fish and various other As the first stars start to peek specimens, the names of which we did out, I look for my favourite spot, the not know. Oh, one thing we noticed Big Dipper. It is nowhere to be found. along the highways was a billboard In vain I search.Orion is up there quite featuring three ladies, and a caption high in the sky, so I calibrate my scope under them saying "WE BARE ALL" look through many scopes, including on Rigel and Castor. With this step and not too far from there was a "Call the 36 incher. Some viewers were a completed, I tell my scope to "Go To" Box". Any connection? little apprehensive having to climb Alcaid. Guess what? The message eight or more steps up a shaky ladder in comes up, "Below the horizon" Now, Tuesday the weather was iffy, order to see through the eyepiece, but the light is beginning to dawn. We are so not much viewing was done, so we once that fear was overcome, the view in a different part of the world. I am had ample opportunity to visit. Among took ones breath away. M51 indeed has completely disoriented. Selah. (Pause those we had a nice social time with spiral arms. M33 has a myriad of little and reconsider) (Greek) (Or is it were Jack and Alice Newton. You all galaxies keeping it company. Even with Hebrew). Anyway, after a little know Jack from his fantastic photos in my 8 inch, we saw things that we had reflection, I look to the north where I S & T and Astronomy magazines. A never seen before, because of murky think Polaris should be, but I do not see nice couple. Actually, we met them two skies. it, but just to the right I see two stars days earlier at the motel where we which I conclude are the two stars in stayed prior to entering the camp And so it went, viewing night the grounds. after night, seminars and fishing day bucket of the Dipper. Discovery! The after day, and the weather? What can I Dipper is completely vertical with the The Southern Cross was quite say? Wonderful. No, it was better than handle and two stars of the bucket visible just above the horizon, and not that, it was Twoterful. One home made indeed below the horizon. All the only were all four stars visible, but we scope that showed some ingenuity was constellations are in the wrong place. did see a fuzzy about one degree to the demonstrated by its owner, a fellow east of the lower star. As I mentioned from Wisconsin. As he deals with After this awesome discovery, earlier, the viewing was absolutely I get back on track. Saturn I have never awesome. (Continued on page 10)

Event Horizon - Hamilton Amateur Astronomers Page 6

ESA's Hipparcos satellite revises the scale of the cosmos

he observable Universe may Sun, according to the Hipparcos data. be about 10 per cent larger Cepheid stars alternately The slowest Cepheid in the sample, l than astronomers have squeeze themselves and relax, like a Carinae, has a period of 36 days and is supposed, according to early results beating heart. They wax and wane equivalent to 18,000 . from the European Space Agency's rhythmically in brightness, every few Hipparcos mission. Investigators claim days or weeks, at a rate that depends on Applied to existing data on that the measuring ruler used since their luminosity. Henrietta Leavitt at the Cepheids seen in nearby galaxies, the 1912 to gauge distances in the cosmos Harvard College Observatory Hipparcos result increases their was wrongly marked. discovered in the early years of this distances. It pushes the Large century that bigger and more brilliant Magellanic Cloud away, from 163,000 This ruler relies on the Cepheids vary with a longer period, light-years, the previously accepted brightnesses of winking stars called according to a strict rule. It allows value, to 179,000 light-years with the Cepheids, but the distances of the astronomers to gauge relative distances Hipparcos Cepheid corrections, an nearest examples, which calibrate the simply by taking the pulse-rates of the increase of 10 per cent. Feast and ruler, could only be estimated. Direct Cepheids and measuring their apparent Catchpole feed this result back to our measurements by Hipparcos imply that brightnesses. own Milky Way Galaxy, and into the Cepheids are more luminous and calculations of the age of globular more distant than previously imagined. Nearby Cepheids are typically clusters, which harbour some of the 1000-2000 light-years away. They are oldest stars of the Universe. The brightnesses of Cepheids too far for even Hipparcos to obtain seen in other galaxies are used as a very exact distance measurements, but The reckoning involves guide to their distances. All of these by taking twenty-six examples and another kind of variable star, the RR galaxies may now be judged to lie comparing them, Michael Feast and his Lyraes, and the Hipparcos investigators farther away. At the same time the colleague Robin Catchpole of RGO arrive at an age of 11 billion years for Hipparcos Cepheid scale drastically Cambridge arrive at consistent the oldest stars. Other estimates of the reduces the ages of the oldest stars, to statistics. oldest stars assigned to them an age of about 11 billion years. By a tentative These define the relationship between 14.6 billion years. This seemed, interpretation the Universe is perhaps the period and the luminosity, needed to absurdly, to leave them older than the 12 billion years old. judge the distances of Cepheids. The Universe. A team of astronomers using zero point is for an imaginary Cepheid the Hubble Space Telescope recently European teams of scientists pulsating once a day. This would be a declared the Universe to be only 9-12 and engineers conceived and launched star 300 times more luminous than the the unique Hipparcos satellite, which (Continued on page 8) operated from 1989 to 1993. Hipparcos fixed precise positions in the sky of 120,000 stars (Hipparcos Catalogue) Mirrors on the Move ... and logged a million more with a little less accuracy (Tycho Catalogue). Since (Continued from page 1) aberration, where the outermost and 1993 the largest computations in the The Schmidt-Cassegrain only innermost rays of light don't focus at have reconciled has to move the primary mirror 2.2cm the same point on the optical axis. By the observations, to achieve a (0.86") to focus that close. In practice, comparison, SCTs tend to have rather hundredfold improvement in the the mirror is made to move several large central obstructions, too. accuracy of star positions compared inches to allow for focusing while using with previous surveys. different-sized diagonals and an Despite these problems assortment of astrophotography and causing less spectacular viewing, the Slight seasonal shifts in stellar CCD-imaging equipment. This is the Schmidt-Cassegrain continues to positions as the Earth orbits the Sun, main reason that they are such popular remain one of the most popular types called parallaxes, give the first direct scopes. purchased by amateurs, today. measurements of the distances of large numbers of stars. With the overall You can't have you cake and Rob Roy calculations completed, the harvest of eat it, too, as they say. For peak optical [email protected] scientific discoveries has begun. performance, there is an optimum The pulse-rates of the stars distance between the primary and secondary mirrors. Changing that distance by as little as 1mm causes an optical defect known as spherical Event Horizon - Hamilton Amateur Astronomers Page 7 Ann's Excellent Digital Astronomy-Flashlight

ere is a project for the turns on both outputs and current flows The heart of the circuit is the 4013 amateur astronomer who has through both R1 and R2. The LED is a CMOS dual type D flip-flop. Diode D1 a good electronics maximum brightness and about 8 mA protects the 4013 and LED from being background. If you're not good with will flow, 9mA if you leave out D1. destroyed if the battery is accidentally electronics, maybe your electronics With D1 in, R1 = 500 ohms and R2 = connected in reverse. Capacitor C1 hobbyist friend would find this an 1.4 K ohms, about 12 mA will flow. reduces multiple switching caused by enjoyable challenge. This is pushing the 4013 since the first voltage fluctuations when the 4013 flip-flop is passing about 8.5 mA, and There are two things that I find are switches. Switch S1 should be a good the output limit is 10 mA. It is VERY weak points in astronomy flashlights. snap action SPST normally open push important that a super-bright LED be First, they do not have a variable light button switch. I used a PC mount used, otherwise you will have an intensity. Since light levels and dark keyboard switch because its low profile ornament, not a useful flashlight! adaptation can vary a lot during an allowed it to be surface mounted. The evening, a variable intensity light would large flat button seems ideal and the Unfortunately, Radio Shack has be nice. Second, the switches are often price is low. Resistor R3 pulls the input discontinued the super-bright LED, but poor. Either the switches don't last or voltage on pin 3 down to low when S1 some stores still have it in stock. If you they are awkward. The AEDAF gives is not depressed. When S1 is depressed, buy one elsewhere, make sure it is rated you variable intensity with four pin 3 goes high and the first flip-flop for at least 2,000 mcd at 20 mA. brightness levels and uses an easy-to- output goes low. Current flows through Enjoy! use push-button switch. R2 and the light emitting diode, LED1.

The next S1 depression switches off the Bill Tekatch, (905) 575-5433 I used a pocket size infrared remote first output and the second, on. Current [email protected] control case to house the circuit. It is a flows through R1 and LED1. Since R1 handy size, comfortable to hold, fits in is half the resistance of R2 the current a shirt pocket, will not roll and comes flow is higher and the LED glows with a convenient built-in nine volt brighter. The third depression of S1 battery holder. Rob’serving ...

(Continued from page 3) · 11&12- BCA observing nights. · 19-2am Moon 4 deg. S of Mars. · 21- Lyrid Meteor Shower peaks (washed out by full Moon.) · 29-2am Mars stationary against the background of stars.

· Mercury is an evening *star* at the beginning of April. · Mars rises at sunset in mid-March and is visible all night. · Jupiter rises earlier each morning and will soon be worth getting up for. · Neptune & Uranus are a bit west of Jupiter in the morning sky. · Saturn & Venus are too close to the Sun for viewing.

Rob Roy, Observing Director [email protected]

Event Horizon - Hamilton Amateur Astronomers Page 8

ESA's Hipparcos satellite ...

(Continued from page 6) interpret Mira as a senile star slightly anticipates a warm debate among billion years old. The Hipparcos more massive than the Sun. It has astronomers. Should the Hipparcos Cepheid result increases that Hubble- swollen into a red giant and started Cepheid results be taken at face value, inferred cosmic lifespan to 10-13 oscillating, as a prelude to greater with all their implications for the size billion years. instabilities that will in due course fling and age of the Universe? He remains the outer layers of the star into space. confident that the issue will be settled "I hope we've cured a by other results quarried from the nonsensical contradiction that was a Hipparcos fixes Mira's Hipparcos data. headache for cosmologists," Michael distance at 420 light-years. Other Feast says. "We judge the Universe to astronomers have gauged the apparent Further Hipparcos studies of be a little bigger and therefore a little width of the star, as seen from the variable stars, including the RR Lyraes, older, by about a billion years. The ground, so the Hipparcos team can are in progress. Also relevant to the oldest stars seem to be much younger compute the diameter of Mira as 650 distance scale are differing quantities of than supposed, by about 4 billion years. million kilometres -- somewhat wider heavy elements present in stars of If we can settle on an age of the than the orbit of Mars. If the Sun were different ages, which can affect their Universe at, say, 12 billion years then in Mira's state it would swallow up the luminosities. Any remaining confusion everything will fit nicely." Earth and all of the inner planets. on this point will be dispelled by mainstream Hipparcos research devoted Feast and Catchpole have also Astronomers knew that Mira to the basic astrophysics of stars of cleared up a mystery about the nearest was big, but the Hipparcos result different ages of origin, and at different and most familiar Cepheid variable. confirms that it is too large to be stages of their life cycles. This is Polaris, the Pole Star. oscillating in a simple fashion. Again Imperceptibly to the human eye, its its variation is an overtone, and the Information about Hipparcos is brightness varies at a relatively high same is true of some other variable stars accessible on the World Wide Web: rate, every 3 days. That should make it, of the http://astro.estec.esa.nl/Hipparcos/ by the Cepheid rule, a feebler star than same type, known collectively as the hipparcos.html it appears to be. Miras.

Hipparcos fixes the distance of The sixteen Miras in the Polaris at 430 light-years, and the survey are mostly 300-1000 light-years researchers conclude that Polaris away, at distances more comfortably pulsates with an overtone, at a rate 40 within the grasp of Hipparcos per cent faster than expected for a parallaxes. Before Hipparcos, there was Cepheid of its size and luminosity. only one fairly good measurement of a Several other Cepheids gauged by Mira distance, for the star R Leonis. Hipparcos also exhibit overtones. Were Even in that case, Hipparcos adjusts the Ask the these not recognized as fast pulsators distance they would give false impressions in the from 390 to 330 light-years. Cepheid distance scale. “Expert” ... Applied to the Large (Continued from page 2) The miraculous stars Magellanic Cloud, where Miras have Using the software program been detected, the Hipparcos Mira scale “Earth Centred Universe” to measure Another famous variable star puts the galaxy at 166,000 or 171,000 the distance between the north ecliptic pulsates at more than twice the light-years, depending on the method of pole and the north galactic pole shows frequency that theorists would expect. calculation preferred. This result is that they are approximately 60 degrees This is Mira, the prototype of the class intermediate between the commonly apart. If you look in a star atlas such as of stars investigated by Floor van accepted distance to the Large “Sky Atlas 2000.0” you can see that the Leeuwen and his colleagues, using the Magellanic Cloud and the new result Galactic Equator is tilted 60 degrees Hipparcos data. To an unaided eye, from the Hipparcos Cepheid scale. from the Ecliptic. Omicron Ceti appears and disappears in a cycle of 11 months. In the 17th It is probably a lot easier to Century astronomers named it Mira, the Only the beginning understand this out under the night sky miraculous star. Astrophysicists today with a few star charts handy. Join us a Michael Perryman, ESA's one of our scheduled observing sessions project scientist for Hipparcos, to learn more. Event Horizon - Hamilton Amateur Astronomers Page 9 April Night Skies

Event Horizon - Hamilton Amateur Astronomers Page 10 Winter Star Party ...

(Continued from page 5) Rockwood. The 401 from Windsor to people with handicaps, his scope, a 20 Too soon we had to break the Guelph Line was snowbound. incher, is so constructed that one can camp and start back for home, but the Traffic moved at 40 kmh. Vehicles remain seated because the eyepiece is memories will be everlasting. The Dobs were in the ditches, vehicles were always at the same level. A long handle dominated the field, but there was a upside down , vehicles were facing controlled the azimuth and as a good smattering of LX200's 8" 10" 12" west in the eastbound lanes, it was a wheelchair moves alongside, so does There was a goodly number of young real smozzle out there, but we took our the scope rotate. He is much in demand people there which was good to see. perfectly good time and arrived home in his home town and has had much The door prize, an 8 inch LX200 was safe and sound to a driveway full of success with his design. not won by us, but we did cheer the snow. A great homecoming. person who did win it. There were some We did meet some folks we super prizes, but alas, Oksana's luck had Oh, lest I forget, I picked up a met last year, and added some new run out and all we will return with will GPS 38 down in Key West. It was the acquaintances this year. Some folks left be our sun tans. last one the store had so they dropped the site on Friday as they had to go to 10 dollars off the price. Was 119 dollars work on the Monday, and to fill the By way of the Kennedy Space U.S. a good price? void next to us, two ladies from Center, we made our way back. We Jacksonville camped there. They just were in the area for the space shuttle See you all at the next meeting. came for the weekend. Very nice folks. takeoff, but somehow, we slept right through it. Disney World was a nice Oksana and Lou Darcie The food in the starlight cafe diversion, so nice in fact, we stayed an Astronomaires Extraordinaire. was excellent. There was a good variety extra day in the area. and lots of it. All in all, we rate the Winter Star Party with five stars out of Friday and Saturday we were five. The staff were great, the security seriously on our way back to Canada, was excellent, the site was A-one and and on Sunday morning at 0915 we left the skies were just marvelous. Who Toledo, Ohio in a snow storm which could ask for anything more? did not let up until we got to

CALENDAR OF EVENTS

¨ Tuesday, March 18, 7:00 PM HAMILTON AMATEUR JUNIOR ASTRONOMERS - Mac Burke Science Building, Rm B148 (beside the planetarium) Topic to be “Comet Hale-Bopp”. For more information contact Rosa Assalone at 540-8793 ¨ Friday, March 21, 7:30 PM COUNCIL MEETING - At the home of Stewart Attlesey. Call Doug at 525-9140 Extension 23186 if you are interested in attending. ¨ Thursday, April 6, 8:00 PM ROYAL ASTRONOMICAL SOCIETY OF CANADA Hamilton Centre - General Meeting - McMaster University Medical Building Room 1A6. ¨ April 4,5,11,12. 8:00PM BINBROOK OBSERVING SESSIONS - Proposed observing nights. For confirmation or directions call Rob Roy (692-3245) or Ann Tekatch (575-5433) ¨ Friday, April 11, 11:59 PM EVENT HORIZON DEADLINE - Please submit your articles and pictures to Stewart Attlesey, [email protected] or modem (905)827-9105 or snail mail to 1317 Mapleridge Cres., Oakville, L6M 2G8 ¨ Friday, April 18, 7:30 PM HAA GENERAL MEETING - at the Spectator Building auditorium. Speaker to be announced. Parking lot observing, weather permitting. ¨ Saturday, March 22, 8:00 PM COSMOLOGY DISCUSSION GROUP - Room B148 (next to the planetarium,) Burke Science Building, McMaster University. The topic will be "Near,At, and Faster than the Speed of Light" For more information contact Bill Tekatch at 575-5433 or [email protected] ¨ Saturday, May 24, 8:00 PM COSMOLOGY DISCUSSION GROUP - Room B148 (next to the Planetarium) Burke Science Building, McMaster University. Topic will be "Reality". For more information contact Bill Tekatch at 575-5433 or [email protected]

Event Horizon - Hamilton Amateur Astronomers