Download PDF version:
A S T R O N O T E S
The Newsletter Magazine of the Ottawa Centre of the RASC
Vol. 23, No. 2 $5.00 a year February 1984
Editor.......Rolf Meier......4-A Arnold Dr.......820-5784
Addresses....Art Fraser......92 Lillico Dr.......737-4110
Circulation...Robin Molson....2029 Garfield Ave...225-3082
OBSERVER'S GROUP MEETING - JANUARY 6, 1984 David Lauzon
Chairman Gary Susick opened the meeting at 8:15 pm with 35 people in attendance, of which 31 were members. He familiarized members with our two observing sites, IRO and Quiet Site, and encouraged all to take advantage of them. In place of Vice-Chairman Malcom Lambourne, Gary introduced the speakers.
First up was comet coordinator Dave Fedosiewich with a presentation on upcoming comets. Comet P/Crommelin, which reaches perihelion on February 20, is expected to be brighter than predicted in the Handbook. Comet P/Encke reaches perihelion on March 27. More details will follow in the next couple of months. Dave's talk then centred on Halley's Comet, due in 1986. The expected magnitude will reach 5.3. See you then.
Next was Jack Horwood, giving his report on "armchair astronomy" and the Quadrantid meteor shower. By tuning in to a distant fm radio station, it is possible to hear the radio echos off the ionized trail of a meteor passing through the atmosphere. Jack recorded this shower over a period of time with a chart recorder. This gave meteor echos on the chart when it was analyzed.
Fred Lossing commented on an article written by Norman Sperling from Chabot College, talking about the Ottawa Centre of the RASC, and how lively this centre is. Fred then commented on how everything goes in cycles, and how important it is to get more involvement from members. This is crucial for the club's existence.
Following Fred was Peter MacKinnon, presenting an award to Stan Mott in honour of his outstanding contribution to the Ottawa Centre. In commemoration of his retirement from Librarian, the library is now known as the "Stan Mott Library". A special plaque was then given to Stan with the best of wishes from all members - Thanks, Stan!
Variable Star coordinator Sandy Thuesen talked about the puzzling subject "Where are all of the Variable Star Observers?". To get these people out of the closet and onto the scopes, Sandy had various handouts on how to observe variable stars. Anyone with observations is urged to contact Sandy to get started. There are many reference books on the subject in our library, and pages 148 and 149 of the Observer's Handbook 1984 would be worth reading.
Gary Susick, our Deep Sky coordinator, discussed astro finder cards. His detailed cards would be very useful at the scope. Gary then proceeded to the basics of astrophotography. A simple formula can be used to approximate the image size of an object on the film. He then showed slides expressing this idea of using different focal lengths, showing the size on the film.
Observatory Committee Chairman Robin Molson stated that the observatory is snowed in. People using this facility should not obstruct the farmhouse upon arrival.
Finally, Gary Susick closed the meeting at 9:49 pm, when people were invited for the unveiling of a plaque for Stan at the library.
* * *
THE MINI MAGELLANIC CLOUD
The Large and Small Magellanic clouds were named after the explorer Magellan, who was one of the first to sail around the world and into the southern hemisphere. The more recent find of the Mini Magellanic Cloud Remnant (MMCR) was made by Don Matthewson and Vincent Ford.
However, they did not explore a new earthly sea to make
their discovery. Instead, they used a radio telescope, two optical telescopes, and a computer. In fact, the new system is actually seen in the same part of the sky as the Small Magellanic Cloud (SMC), but the component belonging to the MMCR was isolated using radial velocity measurements. The MMCR is about 30,000 light-years away from the SMC, with a differential velocity between the two of about 40 km/sec. Thus the milky way has at least 3 satellite galaxies.
THE GEMINIDS OF 83 AND BEYOND
Due to the mysterious way that meteor showers seem to place themselves on a night of either bad weather, the full moon, or the middle of the week, the Geminid shower of 83 was only briefly observed. On the night of Dec 10/11, 1983, 3 brave observers trekked out to our meteor observing site known as the Quiet Site. These people were Rolf Meier, Linda Warren, Sandy Thuesen, Dave Fedosiewich, and myself. Sub-zero temperatures prevented us from observing for more than 40-minute stretches. Between 23:08 and 23:48, 17 meteors were observed, 10 being Geminids. Between 23:18 and 23:28, a -2 meteor lit the ground. The second stretch, between 00:22 and 00:52, yielded 10 meteors, of which 4 were Geminids.
These low rates may be accounted for by the fact that the maximum was in a few more days yet, the mag 5.5 skies, and a faint aurora in the north.
As mentioned earlier in this article, many variables affect whether or not we are going to see meteors, as was the case for the Quadrantids this year. They were not observed visually due to snow.
Fortunately, there are many other chances to observe meteors this year. Each shower will be discussed as the months for them roll around, but here is a brief chart summary of what to expect in terms of major shower activity.
shower date of max(UT) moon favourable?
Lyrids Sun Apr 22 LQ yes
Eta Aquarids Fri May 4 NM yes
S Delta Aquarids Sat Jul 28 NM yes
Perseids Sun Aug 12 FM not at max
Orionids Sun Oct 21 NM yes
S Taurids Sat Nov 3 FQ yes
Leonids Sat Nov 17 LQ yes
Geminids Fri Dec 14 LQ yes
Ursids Sat Dec 22 NM yes
As you can see from this chart, if you are a weekend observer, get your sleeping bag, warm clothes, mosquito mesh, insect repellent, and your will for the unexpected out, because it looks like a good year.
Anyone wishing to become part of the ever-growing meteor team, call me at 745-7962.
LETTERS TO THE EDITOR
Do the participants of graze expeditions feel that because they are in the dark, therefore everyone else must be also? If this is not the case, then how about a little more explanation for some of us who are temporary expatriots, about the incident that was partly reported?
Who was this damsel who appeared out of the darkness like a comet looking for a wrench? Did she say what kind of a wrench? Did she say what for? There are a lot of questions left unanswered and it is keeping us in suspense.
Was she perhaps a ploy by a rival graze expedition out to destroy the carefully tuned night-vision of a dedicated group of observers with her high beams? And did she ever find a wrench? Or why did this disturb the group at the next station so that they observed the wrong star? "Never underestimate the power of" may be truer than at first thought.
Well, we in the hinterland are still waiting in suspense. How long did it take to get that group fitted for straightjackets?
Sun City Center, FL 33570
Well, Gordie, you may sit there very smugly by your pool sipping your rum and coke, and watching the sun set over the city center. But back here in the frozen wasteland the other 199 members of your Centre are freezing their (everything) off, scraping up enough observations through the frost on their eyepieces, to write up something to fill this little rag, which you probably are reading this very minute. In any case, we'll see you again in the summer. -Ed.
IRAS NO LONGER ACTIVE
The Infrared Astronomical Satellite stopped operating in November. During its lifetime it made many important contributions to astronomy, many of which are written up in the January issue of Sky and Telescope. Scientists will be kept busy looking at the results for many years. A new IRAS is not planned for the near future.
VARIABLE STARS OF THE MONTH
R Leonis and T Cephei
Now is your chance to become acquainted with two interesting long-period variables, R Leonis and T Cephei. These Mira-type stars are presently at or near maximum brightness and are easily found in binoculars. If you have a small telescope you will be able to follow them throughout their entire cycles this year.
R Leonis is located about 5° from Regulus and is in the same binocular field of view. In telescopes, R forms a triangle with two stars of magnitudes 9.0 and 9.6 lying to the west, making the field one that is easily remembered and quickly located.
T Cephei is a circumpolar variable and can be followed year round, as it is never below the horizon. Finder charts for both stars accompany this article.
Check these stars out once every 10 days or so, using the chart suited to your instrument. Use an "a" chart for binoculars, and a "b" or "c" chart for telescopes. Compare brightnesses with neighbouring stars shown on the chart and record your observations in a log book, noting the date and time of your observation, and the instrument used. Later on, convert the time to Julian Date.
When observing variables which have a red colour (as these do), it is recommended that estimates be made by the quick-glance method, rather than by prolonged staring. Red stars tend to excite the retina of the eye when watched for any length of time, and accordingly, appear to become unduly bright. This is known as the "Purkinje Phenomenon" and can result in error when making estimates.
On the finder chart for T Cephei, I have included two other variable stars which you might like to observe.
Delta Cephei is the prototype for another type of variable star known as the Cepheids and is an excellent introduction to variable star observing. It is easily seen without optical aid, but binoculars help for magnitude estimates. Compare it every clear night with Zeta (3.6) and Epsilon (4.2) and you will find its light varies by just under one magnitude in 5.366 days.
Mu Cephei, Herschel's "Garnet Star", one of the reddest stars in the sky, is an irregular variable. Its cycle does not follow a set pattern, but watching its light variations is interesting nonetheless. Make an estimate about every 2 weeks.
Burnhams Celestial Handbook, Vols 1 and 3
Variable Stars, J.S. Glasby
Variable Star Observers Handbook, John Glasby
* * *
EPSILON AURIGAE Sandy Thuesen
Throughout this coming spring, observers will have an opportunity to witness a rather rare event and one that will not be repeated for another 27 years. Epsilon Aurigae, a very unusual eclipsing variable, is coming out of eclipse and will gradually brighten over the next five months from minimum magnitude 3.8 to maximum of 3.0. The star began fading from its normal brightness in the summer of 1982, reached minimum last winter, and was predicted to begin its rise again in January, 1984, reaching maximum in June this year.
Epsilon Aurigae is located about 3° southwest of Capella, in the asterism known as "The Kids". A finder chart with the variable circled accompanies this article. It is easily seen with the unaided eye, but binoculars would make magnitude comparisons easier. Compare its brightness to that of Zeta (also slightly variable, but its light should remain constant in 1984) and Eta each time you are out this spring.
The two components in this odd system revolve about their common centre of gravity in the exceptionally long period of 9883 days (27.1 years). The visible star is an F2 supergiant, with a mass estimated to be approximately 15 times that of the sun. The exact nature of the invisible eclipsing companion is not known, and a number of studies over the past years have described it variously as an enormous infrared star, ionized and partly ionized clouds of gas, "a swarm of meteorites" (a theory in 1924), and even a black hole. Its true nature, however, still remains a mystery.
Burnhams Celestial Handbook, Vol. 1 pp 266-272
Sky and Telescope, May 1982; "The Mystery of Epsilon
Aurigae"; pp 460-462
Astronomy, August 1983; "The Mystery Star"; pp 66-71
Position: R.A. (2000) 5h 07m Dec. +43° 49'
Period: 9883 days
Magnitude: 3.0 - 3.8
Note: Charts for both binocular and telescope use for all variables mentioned in Astronotes will be available at Observer's Group meetings or, if you are unable to attend, please call me at 829-7514 and they will be mailed to you. Also available will be copies of a "beginner's handbook" on variable star observing. Anyone wishing to observe stars other than those mentioned (and we hope many of you will) is invited to check the list we of have of charts available. I look forward to receiving any observations you make. If you run into any difficulty or need information, please contact me.
Here are the answers to last month's quiz
1) July 31, 1985
2) about 2.6 seconds
3) about 32
5) October 7, 1959
6) in the polar regions
7) about 0.1
9) Ranger VII
and 10 more questions:
1) How large a telescope is needed to resolve Betelgeuse into a disc?
2) In what constellation is the centre of the milky way?
3) What kind of object is associated with Oort?
4) Who discovered Uranus?
5) What is Neptune likely to have, but is as yet undiscovered?
6) What star name translates to "prankster"?
7) What is the evening star?
8) What is the dustiest galaxy?
9) Where is the Fly's Eye?
10) Who first correctly explained the cause of the auroras?
CHAIRMAN'S REVIEW - 1983
As one looks back over 1983, one sees a year of decreased activity by the members, punctuated by a hopeful upward surge toward the end of the year. The recent increase may be due to a number of successful star nights held during the summer.
These "regional" star nights were prompted by a suggestion made by Rob McCallum made at a council meeting. With his help, these were organized for the following locations: D. Aubrey Moodie Intermediate School (May 13), Vincent Massey Park (June 17), and IRO (August 12, October 8, and October 9). These star nights were very good for attracting members of the general public, who were able to view the sky very nicely with our members' telescopes. I believe that some of our new members first found out about the club at one of these star nights.
The star nights at IRO were very well attended, and we were blessed with clear skies. Many members brought out their telescopes for some great views.
The meeting highlight of the year was the June meeting, which was Instrument Night. Observer's Group members had a chance to show the rest of the Centre what kind of stuff they build and use. Max Stewart's telescope, which was on display, went on to win a prize at Stellafane later in the summer.
Speaking of conventions, many Observer's Group members went to both Stellafane and the General Assembly. In addition to Max, Linda Warren and Steve Dodson also entered telescopes. Congratulations to the winners!
At the GA, Jim Hayes and Frank Roy entered displays. About a dozen members made the trip to Quebec City.
But we finally had some successful grazing occultation expeditions. Coordinator Brian Burke is to be congratulated for his persistence in getting observations from grazes on August 3 and September 3.
This year's total solar eclipse was attended by regular Patrick Brewer, as well as Ian Henderson. Pat gave a talk at the July meeting about the June 11 eclipse.
For many new members (and non-members, for that matter), a well-publicized comet provided some good views in the early summer. Comet IRAS-Araki-Alcock reached naked-eye visibility during its close approach to the earth. It was a brief but spectacular sight for those who saw it. Its fast motion across the sky made for some exciting observing.
Meteor coordinator Dave Lauzon continued to develop a meteor-observing program for the Observer's Group. The Perseids, in particular, were well-observed from IRO. The Geminids were a disappointment, mainly because of the bitter cold (and a lack of coffins). Nevertheless, Quiet Site can still be considered a favourable location from which to observe meteors, mainly because of its accessibility. The site is being maintained by the Quiet Site Committee for use by members for events such as meteor sessions. The sky there is acceptable.
Congratulations are in order to the Observer of the Year for 1983, Sandy Thuesen. Here is someone who has been with the group for a short while, and was propelled by the enthusiasm generated at meetings and star nights to become a proficient observer. Congratulations also to Robin Molson, winner of the Merit Award for his tireless efforts towards the continued enjoyment of IRO by members.
Good luck to Gary in 1984!