AstroNotes October 1970

FALL PROGRAM . DEEP SKY WONDER NIGHT - VERMONT . COMET ABE . HOW GOOD IS THE DALL TEST? . PLANETARY NOTES . DEEP SKY - 253 . VARIABLE STARS

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AstroNotes

The Newsletter of the Ottawa Centre, RASC

Vol. 9, No. 8 October, 1970

Editor: Tom Tothill 22 Delong Drive, Ottawa 9
Addresses: Howard Harris 667 Highland Ave, Ottawa 13
Circulations Ted Bean 399 McLeod Street, Ottawa 4


EDITORIAL

Murphy's Fourth Law is that the typing of Astronotes invariably coincides with the best observing weather of the month.

GONE OBSERVING

FALL PROGRAM

Rick Lavery

The Observers Group would like to announce that it
will be showing the movie "The Violent Universe" on
Friday, November 6, at 8:15 pm. This is a full length
movie of 148 min.

Commencing with the October meeting the Group is
hoping to present various films relating to "Forces at
work in the Universe".

Finally, at the January meeting we would like to
discuss a book by Immanuel Velikovsky, "Worlds in
Collision". Velikovsky proposes a theory of cosmic
catastrophism, a view which did not at first sit very
well with the astronomers of the 1950's. However, his
theory has survived (?) the test of time and many new
discoveries since 1950 have backed up his work.

* * * * * * * * * * * * *
OBSERVERS GROUP MEETING - SEPT 4 ?

About thirty were in attendance, Rick Lavery in the chair. Summer activities were reported upon in entertaining fashion by Ken Hewitt-White and most of the coordinators. The main presentation was slides of Stellafane, 1970 taken by the numerous Ottawa participants.
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DEEP SKY WONDER NIGHT - VERMONT

Tom Tothill

The Montreal Centre's annual Deep Sky Wonder Night was held as usual at Mr. and Mrs. Sidney Sundell's cottage at Montgomery Center, Vt., about 70 miles south and a little east of Montreal. Dr. Lossing and I took advantage of a favourable weather forecast to drive down for the evening on Aug 29th.

About 15 people showed up from quite a range of places including Albany, Connecticut, Boston, and New York. Supper was enjoyed at the Sundell's and then, Mrs. Sundell's personal prediction that it would clear up proving correct, we all drove about 5 miles up the hill to Andy Anderson's commodious cottage on top for an excellent night of viewing and conversation with those characters - Sidney, Andy, and Walter Scott Houston.


COMET ABE

Allen Miller

For those with binoculars or a telescope, try looking north for this intruder. Abe is probably the best telescopic comet to come around for a long time. On the morning of Sept 12 (same date as drawing) about a half a degree of fan tail was visible in the eight-inch. I estimated its magnitude at about 6.0 . Another interesting point was that it moved quite considerably during each observation. By comparing a drawing made by Steve Craig with one I sketched 50 minutes later, the comet had shifted in the field by about one 'head' diameter. Steve's guide star is marked x. The same star had "moved" to O in my drawing. The predicted coordinates (from Sky & Telescope, Sept) are given below:
RA Dec
Oct 1 16h 16.4m +28° 50'
Oct 6 16h 11.2m +23° 53'
Oct 11 16h 07.4m +19° 45'


HOW GOOD IS THE DALL TEST?

Tom Tothill

The Dall test (ATM-3) is one of those simple but extremely clever ideas on a par with the Foucault test which it supplements. The Foucault test is perfect for a spherical surface and certainly usable at f/7 and longer focal ratios. However when you get down to f/5 the paraboloidal shadows become very stark and it becomes difficult to judge the crest with certainty. Dall's idea was to put a simple plano-convex lens in front of the pinhole, flat side towards the mirror. The lens puts spherical aberration into the light beam before it hits the mirror, which is opposite in character ("within limits", as Dall puts it) to that of a paraboloidal mirror. Thus the mirror darkens evenly all over when the pinhole image at the centre of curvature is cut
with a knife edge.

To investigate what Dall meant by "within limits", I wrote a ray-tracing program for the computer. It takes a ray from the pinhole, refracts it through the lens, bounces it back from a perfect paraboloidal mirror, and calculates where it will cross the optical axis. all the rays cross it at the same point, the Dall test 7 is perfect. Of course, you can adjust the positions of
the lens and pinhole any way you want. I find that Dall's actual recommendations for a mirror like our 16-inch f/5 lead to the edge zone coming to a focus .053 in closer to the mirror than the centre zone, the change coming mostly near the edge. So the edge should appear to be 'turned up' to be correct. It is distinctly better to put the knife-edge about 0.6 in inside the centre of curvature of the central zone of the mirror, moving the lens back accordingly. This brings all rays to a focus within a range of .016 inches along the axis and should show a  practically 'flat' mirror, our actual lens is not strictly 'plano' in front, but ¼ -wave hollow in the middle and with a turned-down edge. These errors are exactly what is needed to give a perfectly flat Dall test on a perfect paraboloidal


PLANETARY NOTES

Doug Beaton

Two planets, Jupiter and Venus, were of major interest this summer. For Venus I had planned to take consecutive pictures to show its growing size and brightness and decreasing phase during the summer. This project fell through due to a tree which obscured my view to the west. Observations were therefore limited to the daylight hours, which inproved clarity but did not permit photographs. During the summer several dark markings were seen in 8" scopes by 1½ experienced observers, without the use of filters.

Jupiter was the main target for observations. Rolf Meier and myself completed 69 drawings in a space of only 58 days. I also received several more which brought the total to about 80. During two hours on the night of June 13-14, four observers made 8 drawings and I also took one photograph. Telescopes of 6, 8, and 10 inches were used. Rolf and I found one observing technique to be the best. This was to make a quick rough drawing, then make a good draft as soon as possible and check it with someone else's. Errors were noted and corrected in a   third drawing. It also helps to have both people look through the same scope and discuss detail as it becomes visible. This was the way that Rolf and I tried to make most of our  drawings and it gave excellent results.

Using the Red Spot, I determined a rotational period of 9 hours, 51 minutes exactly, which is not far off the true time for System II belts. Poor physical detail on the System I belts caused an error of ± 3 minutes on a timing of 9 hours 52 minutes. The period of rotation for System I should have been shorter by several minutes than the System II area.

With the large number of drawings it was possible to make some generalizations about cloud detail on the planet. First, there appears to be three permanent white spots in  the S. Temperate belt, one being south of the Red Spot. It appears that they have been there for quite a few years. This same belt has a fainter companion to its north which ’curved' around the Red Spot, creating two lighter-coloured spots on the north-south ends of the Spot. There are two dusty S. Equatorial belts, the northern one being harder to see than the southern. The two orange-hued belts of last year apparently have separated and become fainter to form this year’s pair. These belts contain many white spots and black swirls of clouds which curled
from the N. Equatorial towards the east and west of the planet. The N. Equatorial was also greatly changed from last year, for it was now one major and one minor belt instead of two  major belts. The minor belt was about 2000 miles to the north of the major belt, and was occasionally seen to have made contact with this belt. Once, under super-ideal conditions, the  major belt was seen to be divided into two belts. There were a few white spots that were actually in the interior of the major N. Equatorial belt. A S.S. Temperate belt was usually seen as
well as a N. Temperate band, yet little detail was seen in the polar caps other than a lighter shaded cloud in the south cap.

I hope these few observations coincide with your personal notes and if they don't I’d certainly like to hear about it. These notes were made by only four different people and could use some more verification. So if you have any observations, whether written down or not, try and let me know.
* * * * * * * * * * * * *
Your Coordinator is the one guy you can be sure will not be bored when you tell him what you saw in his line of country. Now that Saturn is becoming available before the dim grey hours, why not make a point of calling Doug within 24 hours each time you make an observation?
His number is 224-1789. -Ed.
* * * * * * * * * * * * *

Confucius Say:

Fastest way to lose friend is: have him adjust mirror while you yell from draw-tube.
Fastest way into psychiatrist's office is: do whole job yourself.
* * * * * * * * * * * * *

WARNING!!!

It is reported that THE MIDNIGHT PUNSTER has been raiding the Quiet Site and the disease is spreading. A portrait of Dave Paterson is labeled "Gibbous Phase" and the new enclosure for the Schmidt camera is called "the SOME INTERESTING METEOR PLOTS Ken Hewitt-White It seems that Sky & Telescope was perhaps wrong in saying that the B.A.A. Handbook predicted a split in the Delta Aquarid meteor shower. Although plots were few and far between in July, it seems reasonably sure that all Deltids came from one radiant this year. Since the other radiant matches that of the May Aquarid shower, I think that there was probably a printing error somewhere.

The 1970 Perseids flopped. There were more Perseids seen in one night of 1969 than in all of 1970. However, some good plotting was carried out and we found some interesting results. For a nine hour period stretching over three nights, John Conville and I plotted 15 'stray' Perseids coming out of a radiant in Northern Cassiopeia. They had Perseid characteristics and radiated only twenty degrees from the parent radiant. Perhaps the material in the Perseid orbit split up a bit this year. We need more plots to find out and any other information from
other Centres might help in this regard.

Aug 31, 1970

Dear Tom;-

Have just finished reading Astronotes Vol.9, No.7, and am delighted with the whole issue. I am particularly pleased with the prominent role played by the RASC at Stellafane. Terry Dickinson is known to those who attended the last General Assembly in Toronto, because of the talk he gave in the McLaughlin Planetarium. Ian Halliday and Henri Simard, of course, have long been known for their leadership and ability.

But what sparked this effort was the mention of the two people who have done so much for the Ottawa Centre over the years, namely Fred Lossing and Tom Tothill. The descriptive words "Lossing Lashup" and "Tothill Terror" which described the two prize-winning efforts, indicate the basic friendship and comraderie that exists among the members of the Ottawa Centre.

Also, while pen is in hand, I must admit to a long felt desire to express a word of praise for the intelligent enthusiasm which is evident among the younger members
of the Centre. I expect that the RASC is going to experience some changes within the next few years, and these younger people are the ones who will be at the
helm. So I face the future with a feeling of security and enthusiasm.

Finally a word of praise to you, Tom, for the effort you have exerted to keep Astronotes going.

Very sincerely yours,

Malcolm M. Thomson
* * * * * * * * * * * * *
All concerned will, I am sure, be tickled pink by these extremely kind words. -Ed.
* * * * * * * * * * * * *

Dr. John Percy, Chairman of CCCOCA, is getting up a National Committee for the 1972 Solar Eclipse. It is thought that Rick Lavery would be the best Ottawa representative on this Committee and his name has been put forward.


DEEP SKY - 253

Allen Miller

If you wish to see one of the most spectacular galaxies
in the sky, move your scope until it is 6° below Beta Ceti.
In a fair sized scope with 40 power, NGC 253 will occupy
about one half the field of view indicating that it is
approximately 3/4 of a degree long. At first glance it
appears similar to M-82 in Ursa Major (broken and mottled)
but a closer look will tell the story better. 253 is
about four times longer and at least twice as bright.
Besides its size, the detail visible is astounding.
Throughout it is mottled with a huge dark rift along its
leading edge. The brightness is so uneven that the
nucleus is barely distinguishable.

For amateurs, this galaxy is a must-see, but don't attempt to see the above detail in the city. A dark country sky is needed and when found you should wonder why 253 is not M-111.

P.S. - Keep those drawings and paintings rolling in, folks. If I get two more deep-sky sheets I will have doubled last month's input.

* * * * * * * * * * * * *
As the Private said to the Armed Forces Dentist:
"Ouch! - Sir!" - Ed.


VARIABLE STARS

Rick Lavery Unfortunately, many observers have not yet given me their summer observations, so that a summary could not be presented this month.

R Scutum made one of its infrequent excursions to a minimum of 8.5 during the summer.

By devious means, Astronotes turns up in unexpected places. We got a nice letter from Professor Da Silva in Brazil with his observations on RX Leporis.

On September 12 Margaret Murray and I visited Montreal. We viewed the Dow Planetarium's showing of "And In The Beginning" a very mediocre presentation of the beginning of Creation.

We spent a very enjoyable evening with some of the Montreal Centre members. John Alcock presented a series of photos of Comet Abe taken during a single night to
show its position change. He also verified that Comet Abe was at best a magnitude fainter than predicted.(*). The Montreal Centre has completed a 12½-inch f/5
reflector. They have done an excellent job on it. Si Brown discussed with me some additional information that he had obtained on sites for the 1972 solar
eclipse.

We thank Mr. Sundell for the ride back to the bus station.

(*) At the time of going to press (Sept 21) Comet Abe was passing over the top of the Keystone. Since the 12th it has grown quite a conspicuous tail and has lost
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NEWS FROM MONTREAL

Rick Lavery
* * * * * * * * * * * * *
little in brightness -Ed.
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PERSONALIZE YOUR ASTRONOTES!

If you can think of an apt remark, joke, or observation that you should have sent in but didn’t, put it in here: