AstroNotes 1984 June Vol: 23 issue 06

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12

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ASTRONOTES ISSN 0048-8682
The Newsletter Magazine of the Ottawa Centre of the RASC
Vol. 23, No. 6 $5.00 a year June 1984

Editor.......Rolf Meier......4-A Arnold Dr.......820-5784
Addresses.... .Art Fraser.....92 Lillico Or.......737-4110
Circulation...Robin Molson....2029 Garfield Ave...225-3082

 

OBSERVER'S GROUP ICETING - MAY 4 David Lauzon

Chairman Gary Susick opened the meeting at 8:13 p.m. with 36 people in attendance, of which 81% were members. He briefly described our two observing sites, being Quiet Site and Indian River Observatory. A public star night is planned for May 11/12 at Blackburn Arena. Finally, a reminder for members that the June 1st meeting is instrumentation night.

Observatory Committee Chairman, Robin Molson reminded key holders to properly close the observatory and make sure the clamps are fastened. Also he reminded members that May 5 was Astronomy Day in Canada and that many activities have been planned.

Vice-Chairman, Malcolm Lambourne introduced the speakers of the meeting. First up was David Lauzon with an account of the April Lyrids and the Eta Aquarids. The Lyrids were observed during the night of maximum, being April 22/23. Out of 52 meteors seen, 25 were shower meteors. Nine observers watched the celestial fireworks with many new meteor observers. The Eta Aquarids occurred during the night of this meeting and were washed out by a rain shower.

Paul Comision was up next to discuss the visual observations of Quasar 3C-273. This quasar is the nearest, strongest and brightest one visible. For position data, it may be found in the Observer's Handbook on page 168.

Variable Star co-ordinator, Sandy Thuesen discussed the six variables (all binocular types) to be observed for the Variable Star Award. These stars are: Delta Cepheus, Beta Lyrae, RZ Cassiopae, R Scuti, X Herculis and Chi Cygni. Judgement on the observation will be based on quality, not quantity.

Frank Roy presented a slide show to the group showing our meteor observing site (Quiet Site), aurora and various galaxies.

Solar Coordinator, Linda Warren discussed the upcoming annular solar eclipse on May 30th. in Ottawa, the sun will only be partially eclipsed. Linda also commented on the large sunspot group observed in April.

Comet Coordinator, Dave Fedosiewich was up to talk about the poor visibility of Comet Encke, and the fast comet, Comet Hartley-IRAS 1983V. The latter will reach a magnitude of 14 by August.

Allan Reddock presented a slide show of various objects, and subjects, with the new 3M ASA 1000 film.

Planetary Coordinator Rolf Meier presented a talk on the oppositions of Saturn and Mars. Many features can be seen on both planets and this gives amateurs a good opportunity to observe them. The planets can easily be seen with small telescopes from the City.

Dave Lauzon was up once more to talk about calculating the age of the earth and its importance.

Malcolm Lambourne closed the meeting at 9:42 when everyone was invited for refreshments.

* * *

ASTRONOMY DAY AT ST. LAURENT SHOPPING CENTRE Linda Warren

Bleary eyed and woolly in the head, we all set out to the St. Laurent Shopping Centre at about 8:30 Saturday morning. All our material, telescopes, and general knowledge were assembled to dazzle the public and hopefully peak the interest of hundreds. Sandy Thuesen, Daniel Dlab, Dave Lauzon, and I were absolutely delighted with the enthusiasm and interest we received to our display.

We set up on a very long table, the Ottawa Centre display consisting of information on our club, and the spectacular astrophotography of Rolf Meier. Also available were handouts of the May sky charts, Astronotes issues, old handbooks, and more information about astronomy. Oh yes, last but not least, membership applications were available, and some were taken. On sale were 1984 Handbooks and the Observer's Manual prepared by our own members. We each had a telescope - Rolf's 6-inch, Sandy's 10-inch, Daniel's C-90, and my 2 1/4-inch. We treated the public to such views as the lights on the ceiling down the concourse and anything else that might look interesting. Dave Lauzon was manning the 6-inch and this telescope being close to the ground, children were able to easily view the "wonders". Dave commented to me "Now I see why you like to give talks to the kids". Their excitement and awe is contagious.

The interest was overwhelming and we expect to see quite a good attendance at the next meeting.

A young boy made it all worthwhile to me with his statement "You know how long I've been interested in Astronomy - since I was about this high". It was about a foot and a half shorter than his present 4-foot height. But it was the sparkle and obvious joy in his eyes that I found so rewarding.

Finally, as in all such events, thanks must be extended to those who took part. Special thanks to Dave and Daniel for getting up so early on Saturday; to Sandy for her time and effort in the administration and organization; to Rolf for the use of his van; and to Mary Grey of the Museum of Science and Technology for her assistance and support.

* * *

INTERNATIONAL ASTRONOMY DAY - MAY 5, 1984 Gary Susick

Ottawa's first celebration of Astronomy Day was jointly hosted by the Ottawa Centre (RASC), The Herzberg Institute of Astrophysics (NRC) and the National Museum of Science and Technology.

Activities were held at the Museum of Science and Technology from 12:45 p.m. to at least midnight. Excellent organization utilizing a variety of facilities allowed a large number of astronomical topics to be presented. Many Ottawa Centre members including Ken Tapping, Robert Dick, Frank Roy, Gary Susick, Art Fraser, Peter McKinnon, Rolf Meier, Peter Millman, etc. provided at lease five afternoon presentations. Some of the topics discussed included astrophotography, radio astronomy, astronomy as a hobby and a panel discussion titled "Ask an Astronomer".

The evening speaker program was especially popular with two talks given by a member of the Canadian Astronaut Program. An autograph session followed each presentation.

The day's variable weather finally allowed an observational session. The public was treated to such celestial wonders as the 1st quadrant moon, Mars, and Saturn. At least 7 Ottawa Centre members had their telescopes (from 60 mm to 275 mm diameter) available to augment the Museum's facilities.

From the public response, Astronomy Day was a real hit. All signs indicate that this will be the first of many co-operative efforts in celebrating Astronomy Day. Many thanks to all Ottawa Centre members who participated in making the day a great success!

* * *

THE MAY GRAZE Brian Burke

Although two previous graze expeditions had to be cancelled due to unfavourable weather, a third one was launched on the evening of Sunday, May 6. A group of nine met at the K-Mart Store in Bells Corners at 22:00 and from there we drove out to the graze site on the Richardson Side Road. We were able to establish five stations and for the first time all stations had a CHU receiver and all stations were able to receive the time signal very well.

The 8.5 magnitude star was easy to see until the last few minutes when lunar glare began to cause problems. The glare resulted in the star being lost early and then found at a couple of stations as shown in the graze. The predicted time for central graze was approximately 3:27:19 U.T. on May 7.

The graph shows the predicted lunar limb. The five broken lines going across the graph indicate when the star was visible at each station. Where the line is broken indicates that the star was not visible. At our station glare was such a problem that the star was not seen again until it was well clear of the limb, and is therefore off the graph to the right.

First-time graze observer Gary Hanes, assisted by his wife, was at Station 1 and he observed the most events. All stations south of Gary saw a total occultation. Although at some stations more than one disappearance and reappearance were observed, these were probably caused by the glare.

Although most playback times of the tapes were off, indicating weak batteries at the time of recording, this did not present a major problem because the time signal could be clearly heard on all the tapes.  

The separation between stations was 500 metres and this appears to have been too much. A smaller separation may have produced more interesting results and a separation of 200 metres will be tried on the next graze. It would be nice, however, to have at least 10 stations, so do not hesitate to get involved in the next graze expedition. The predictions for the second half of this year should arrive within the next four weeks and I will let you know what grazes lie ahead in the next six months.

VARIABLE STARS OF THE MONTH Sandy Thuesen

For the month of June, Astronotes features two of the program stars for the variable star of the year award - Beta Lyrae, a bright eclipsing binary, and Chi Cygni, a Mira-type lpv. Finder charts for both stars accompany this article and comparison charts ("a" and "b") for Chi Cygni are available from me at any Observer's Group meeting or by calling 829-7514. If you have a telescope and wish to follow Chi Cygni for its entire cycle, there are also "c", "d" and "e" charts available.

Beta Lyrae
This star is the typical example of the "Lyrid" or "bright-eclipsing" type of variable. The magnitude varies with maxima equal (magnitude 3.4) and the minima alternating between 3.8 and 4.1. These variations are due to the mutual eclipses of two unequally bright stars, one larger than the other, which revolve around their common center of gravity in a period of 12.9079 days. The two stars are so close together that their atmospheres are intermingled and both components are ellipsoidal in shape as a result of rapid rotation and gravitational distortion. The stars are also connected by a great filament of gases along which matter streams at high velocity from the larger star to the smaller. Very strange indeed!
Light changes in the star are most easily followed by comparing the star with nearby Gamma Lyrae, which is mag. 3.3. For a few days the two stars will appear of nearly equal brightness, but about every 13 days Beta will fade away only half the brightness of Gamma. The secondary
minimum occurs some six days later.

Chi Cygni
This is the second of the long-period variables to be discovered (in 1686) after Omicron Ceti (Mira). It is one of the brightest and most easily-observed of the lvp's, and is often visible to the naked eye at maximum, reaching a brightness of 4th or 5th magnitude. The maximum recorded brightness is about 3.5. At minimum the star nearly always drops to below 12th magnitude. Chi Cygni is currently at or near maximum and locating the star should not be a problem.

CHI ( X ) CYGNI
Magnitude: 5.1 - 13.3
Period: 407 d. (average)
Type: Long Period Variable

BETA LYRAE
Magnitude: 3.4 - 4.3
Period:12.93599 d.
Type: Eclipsing Binary

***

R CORONAE BOREALIS

Sandy Thuesen

R CrB, that totally unpredictable irregular variable, is back within binocular range, for those wishing to make its acquaintance. This is a star worth watching as it can change abruptly. For several years it can remain at the same brightness around 6th magnitude, then suddenly fade and within a few weeks will have fallen to almost any magnitude between 7 and 15, but normally around 12.5. The minimum usually lasts for several months, but at times can last for years.

Earlier this year, IAU circular 3928 (March 13, 1984) stated that the star was estimated at magnitude 11.7 on February 15, 1984, and in circular 3933 (March 30) had there was an estimate of 9.6 on March 28. I had not been following R CrB and a member's question at the May
Observer's Group meeting on the status of the star prompted an observation on May 16/17. There was no problem locating in in binoculars and estimating it at 7.1, slightly brighter than the 7.2 star in the same field. In the 10-inch scope, however, I estimated the star at 7.3,
slightly fainter. Can't quite figure that out. In any
event, it is certainly easy to spot and if other observers have any estimates, I'd be happy to see them.

 
VARIABLE STAR AWARD - 1984

Sandy Thuesen

Here's a recap on the Variable Star Award and the program stars mentioned at the May Observer's Group meeting.

The Variable Star Award is presented at the Annual Dinner meeting to the observer who has submitted the best quality observations of variable stars throughout the year. Six program stars have been chosen for the award this year (listed below) and a handout containing charts for these stars, together with other observing information, is available for the asking from the variable star coordinator. If the observer wishes to follow other stars in addition to those on the list, he or she is encouraged to do so and observations of these stars submitted will be included in his or her total. However, the 6 program stars are compulsory.

The 6 stars are:

Delta Cephei; Cepheid; period 5.37 days; range 3.6 to 4.5

Beta Lyrae; Eclipsing Binary; period 12.93599 days; range 3.4 to 4.3

RZ Casseopeiae; Eclipsing Binary; period 1.1952489 days; range 6.4 to 7.8

R Scuti; Semi-Regular; period 146 days; range 4.5 to 9.0

X Herculis; Semi-Regular; period 100 days; range 6.3 to 7.4

Chi Cygni; Long-Period Variable; period 407 days; range 5.1 to 13.5

These are all binocular variables that are easily seen in the city, so it is hoped that many will try their hand at variable star observing. For those with, telescopes, Chi Cygni can be followed to minimum. Good observing!

* * *

The summer Solstice occurs in June. This means the shortest observing night of the year. But another phenomenon is most obvious then - the appearance of artificial Earth satellites. Can you explain why that is? You can see a satellite passing by every few minutes. Sometimes, several can be seen in the sky at once. Have fun trying to spot them!

OBSERVATIONS OF MARS

Rolf Meier

As stated in the last few months, Mars came to opposition on May 11, and made its closest approach on May 19. In the last few weeks, I have been following Mars closely, and have recorded observations with photographs and with drawings. There have been nights of fairly good seeing, when the full aperture of the 16-inch could be used to full advantage. On other nights, a 10-inch telescope gave the best views. I have used powers ranging from 160 x to 500 x when the seeing was very good.

The face of Mars that we see "advances" by about 9 degrees every night, if the planet is observed at the same time, because of the faster rotation period of Mars. Thus, in a period of about 40 days, the entire planet appears to have rotated once, if observed at the same time. During the time I have observed Mars, I have watched the phase change, seen haze patches at both poles and at the sunrise terminator, watched the features change, and most recently, have seen the re-appearance of the Southern Polar Cap.

Below are a couple of recent drawings:

May 5/6 1984 01:45 EDT 16-inch at 320 x

May 16/17 1984 23:15 EDT 16-inch at 320 x