AstroNotes February 1969

EDITORIAL . A SIGHTING OF APOLLO 8 . CHAIRMAN'S REVIEW - 1968 . RONCHI TESTING OF MIRRORS . ASTRO-PAINTINGS . 1968 OBSERVER OF THE YEAR AND MERIT AWARDS . WE LEARN BY TRYING

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ASTRONOTES Vol. 8, No. 2 February 1969

Editor: Tom Tothill 22 Delong Dr. Ottawa 9
Circulation: Rick Lavery 1227 Morrison Dr. Ottawa 6

EDITORIAL

The marvellous success of Apollo 8, with its live TV
transmissions of life aboard, the earth and the moon, has
been promptly followed by the release of beautiful colour
pictures of Planet Earth and its ancient satellite. Some
places to look are "The Times" (London) for Jan 6, TIME for
Jan 10, LIFE for Jan 10 and 17, and the undated LOOK special.
To astronomers the biggest surprise may well be the
startling beauty of planet Earth as seen from space. The
gorgeous deep blues of the oceans, the blue-greens of
shoal waters, and the browns of deserts contrasting with
the startling white of the huge cloud whirls is so different
from what we are able to see on the other planets that
it is unforgettable. Astronomers will also have noted that
the only areas with a more or less permanent freedom from
clouds are the great deserts of the Sahara, Chile, and
Australia. The great trade wind belt stretching from the
Sahara across the Atlantic to the West Indies is also
nearly free from cloud, but interruptions of this idyllic
state are liable to occur in the hurricane season.
Our own climes do not exhibit the characteristics of
an astronomers' paradise - as we well know - but we are
stuck with them and with the challenge they throw at us.
The moon pictures are of immediate value to lunar
cartography. The astronauts photographed the strip of their
own orbital track from a high-precision orbit only 60 n.m.
up. This strip will be used to correct the far-side maps
derived from the Lunar Orbiter flights which covered the
whole of the far side but to an accuracy of only plus or
minus 10 degrees or 160 n.m.

The propriety of the astronauts naming far-side
features for themselves and their colleagues is not contested
here. To us it seems far more appropriate than the I.A.U.
proposal to name them after dead astronomers; for the back
of the moon is the one area astronomers cannot possibly
examine. There are plenty of stars to name for those
astronomers who worked on them.

A SIGHTING OF APOLLO 8

Jon Buchanan

First, my congratulations to the crew and all the
people connected with the APOLLO 8 mission, especially
for the pictures of the Earth and the Moon they sent back.
It was announced in the newspapers and on TV that the
Apollo 8 could be seen at about 10 pm Central time, about
one quarter of the distance from the moon to Venus. I don't
know if they planned it, but they made it very difficult
for us to find as Venus wasn't visible here at that time!
Also, to add to the difficulties, hazy clouds covered the
western sky, broken in parts, with no stars visible.
I went out at about 9 : 50 with John Pratt to attempt
to see it. I set up my telescope and aligned it in the
approximate position. (I had gone out earlier and had
estimated where Apollo 8 would be in relation to the moon).
I started a sweeping search for it in the clouded area
and after about fifteen seconds I found my first star in
this area. With faint hopes I left the star in my field of
view. About ten seconds went by, then I noticed that this
star was moving. I re-centred it and John confirmed the
observation.

This object was about magnitude 5.5, probably brighter
because of the haze and the moon; white in colour with a
slight red tinge; moving slowly in a northerly direction.
When I tried to increase the power from 30 x I lost
the object. I had to go back to the lower power and try
again, with success. No details were visible. After five
minutes we went in, fairly sure that we might have seen
the Apollo 8.

Two meteorological technicians in Rivers, Man. sighted
Apollo 8 and after several hours of following it, had it
confirmed at 9:45 pm.

So, hopefully, there are at least four Canadians who
saw the APOLLO 8 as it streaked home on the 26th of
December.
* * * * * * * * * *

"I am sorry that while we were up there we didn't
think to name one of those craters for our space colleague
Komarov, who was killed during a spacecraft reentry in the
Soviet Union in the spring of 1967."
- Frank Borman in LIFE, January 17.

CHAIRMAN'S REVIEW - 1968

Dan Brunton

For several years now it has been traditional that
the out-going Chairman of the Observers Group present a
review of the activities for his year of office. This is
indeed a pleasurable task for me as the Group was by far
more active this past year than in any recent time.
High-lights abound. Meetings were well attended
(there was a record attendance of 73 at the October meeting)
and participation by individuals at the meetings has
vastly improved. Although the Group has become much larger
(mainly due to an increase in the number of Student members)
the informal atmosphere has, happily, remained.
Our Co-ordinators have been superb. Steve Craig and
his Solar Group have produced numerous outstanding observations.
One of the high-lights of their year came quickly
with the observation of the 'White Spot' in February.
Their efforts culminated with Craig being named National
Solar Co-ordinator this Summer.

Equally prolific and qualified has been the work of
the Deep Sky section under the stewardship of Ken Hewitt-
White. The exciting Messier Race, won by Les MacDonald,
was a hard-fought, stimulating experience for all, and
awoke in many of us skills formerly unknown to Science!
Tom Tothill’s Planetary and Lunar Group was also
more active than in any former year and has increased
interest in Lunar Occultations manyfold. Tom's group is
so close to a successful Grazing Lunar Occultation that
they can taste it!

The Meteor Section has not improved so much as the
others. This is far from disappointing, simply because it
is difficult to improve upon perfection! Under Les MacDonald's
iron-gloved rule, the section has been superlative
for many years. Not to be out-done by any of our
other groups, however, they appeared first in the 1968
NRC listing of meteors seen in 1967. For velvet, Peter
Ryback's Ottawa #5 Station came second on the list and
three other Ottawa-based stations were listed.
The Quiet Site has been anything but quiet in '68.
The Meteor Group has completed an ambitious Observing
complex that can accommodate eight observers at once.
Further, the Deep Sky section has set up facilities for
several 'scopes including an 8½" Cassegrain. The Defence
Research Board has been tremendous in their co-operation
and assistance.

This May, the General Assembly heard two papers from
our members - one delivered by Les MacDonald and the other
the work of Rick Salmon. Salmon also 'cleaned up' at the
National Science Fair held in Vancouver! Another achievement
of great note was the winning of first prize for
mechanical excellence at Stellafane by Dr. Fred Lossing.
This is truly a great honour and a well-deserved one at
that!

A very successful Star Party was held at the Quiet Site
in September which drew 63 people. All were tremendously
impressed by the fine array of optical and mechanical
masterpieces, as well as the tasteful and rustic 'decor'
of the "Perrins & Grant Restaurant".
Great interest was shown in plans for improving the
pathetic communications that exist within the RASC, and
several trips to other Centres have been made and planned.
Pressure (though friendly!) was exerted on our Council by
the Group for a National Newsletter.

Rick Lavery's campaign for a large 'scope has gotten
off the ground and definite plans have been agreed upon.
Given time, some money, and a little luck, we should have
a 16" Reflector for the Centre.

Two of our members were honoured for their outstanding
contributions to the Observers Group. Steve Craig was chosen
as the 1968 Observer of the Year and Les MacDonald received
the newly-presented Merit Award. Both were difficult decisions
as there were many highly-qualified candidates this
year.

The Ottawa Council was amazing in its generosity to
the Group. Financial assistance, especially, was both
excellent and invaluable.

We had two Editors of Astro-Notes this year. Peter
MacKinnon did a fine job until the pressures of University
life made it impossible for him to carry on. Tom Tothill
took it over and has succeeded royally. His editorial on
the purpose and worth of the Apollo 8 mission was the
finest I have seen in any issue of A.N. I also wish to
thank him for his superb job as Vice-Chairman with responsibility
for the Observational activity of the Group.

We can all be proud of this past year, thanks to each
and every one of you.

RONCHI TESTING OF MIRRORS

Ken Perrins

The Ronchi test described here is really a modified
version - that is, Ronchi rulings are not used. There are
two reasons for not using Ronchi rulings; they are expensive
and in this test they do not perform as well as a
fine mesh screen. Because of this, some may say the resulting
image is a Moire interference pattern and not a true
Ronchi. However, the test results are the same so we'll
leave this part to the experts.

The Ronchi test consists of passing a beam of light
through a screen (100 to 200 lines per inch) onto the
mirror and back through the screen and viewing the resulting
image. The test set-up is shown in Figure 1. It is
quite similar to the knife edge test and the same rig used
for the knife edge can be used for the Ronchi test just by
replacing the knife edge with a screen and adding a pocket
mirror. The light source consists of a tin can with a
7 watt bulb and about a 1/8" hole. The light is bounced
off the edge of the pocket mirror placed at an angle of
about 45 degrees. The light passes through the screen and
on to the mirror.

The mirror should be mounted on a test stand which
will allow a fine adjustment of its positioning, similar
to its adjustment in the final telescope. This may be
fabricated from two pieces of plywood connected for adjustment
purposes with three 1½" 6-32 machine screws. The point
of light returning from the mirror should, by the adjustment
of the mirror, be passed back through the screen for
viewing. Testing should be done just inside the radius of
curvature of the mirror with the positioning of the screen
such that about six vertical lines are seen. Moving the
screen forward will increase the number of lines seen and
vice versa.

For measurement purposes, calibration lines should be
placed on the mirror. The most satisfactory method is to
hang two pieces of black thread weighted at the bottom and
taped to the top of the mirror with masking tape. They
should hang down in front of the mirror spaced about 1"
apart in the central area (closer if less than a six inch
mirror).

After a coarse adjustment of the mirror to obtain
about 6 lines on the disk, clamp the rig in place and use
a fine adjustment on the screen. Adjust the screen so that
the two centre lines coincide with the calibration lines
in the centre of the mirror. Note the measurement of the
position of the screen on the steel rule. Now adjust the
position of the screen so the lines just coincide with
the calibration lines at the top of the mirror. Note the
reading on the steel rule. The difference between the two
readings is the amount of correction on the mirror. For a
fully corrected mirror it should be r2/R, r being the
radius of the mirror and R the radius of curvature. For an
f/8 six inch mirror this will be 9/96 or 6/64". About 15 to
20% should be allowed due to the inability to measure
exactly at the center and edge of the mirror. This will
make the actual measurement 5/64".

Distortions on the mirror will also be quite evident
from the shapes of the lines. These should be gentle curves

ASTRO-PAINTINGS

Allen Miller

The word "painting" will probably scare most of you
artists away from this field of "capturing the skies". If
you do decide to try it however, you will discover that
this form of art is much more realistic.

I have done all my paintings with water paints using
yellow dots for stars (unless they have a different colour)
and white for nebulae. The size of the dot indicates a
relative magnitude, being larger as magnitude increases
and vice versa. The background is painted with Indian ink,
the only substance that is black enough.

The nebulae are the only difficult objects. For these,
use watered-down paint and apply it carefully with your
brush to show its brightness and size.
Since the pigment is water paint it is obvious that
it must be kept dry. The remedy for this is to coat the
surface with clear plastic - a liquid that is applied to
floors to make them water-resistant.

One final note is: make all your paintings the same
size (for convenience sake) and as accurate as possible.
Your name, the object painted, the seeing conditions and
the telescope power used should be printed on the back.
The location where your painting was done is also helpful.
The Deep Sky co-ordinator is looking for more drawings
or paintings done by observers and since this is going to
be a good year for planets I would imagine Mr. Tothill
would like to see some planetary art work. Let’s try to
make the Ottawa Centre tops in this field also.

* * * * * * * * * *

For Sale:

4-inch f/6 aerial camera lens, mounted in tube, with
60 mm rack and pinion nylon adapter to take 1¼" accessories.
Also: 70° wide-angle Kellner (2 achromats) in adapter to
fit rack and pinion.
Lens can be used for astro-photography or richestfield
visual work.
No mount. Weighs 25 lb approx.
Price for everything $70.00
Philip Cheffins - 729-6879

1968 OBSERVER OF THE YEAR AND MERIT AWARDS

Ken Perrins

This year in addition to the Observer of the Year
Award there is the newly adopted Merit Award for outstanding
service. Candidates for the Merit Award were recommended
by members and the Awards Committee.

After due consideration of all candidates, it was the
unanimous decision of the Awards Committee that Les
MacDonald be presented with the first Merit Award for his
efforts towards the development of one of the best meteor
observing teams in Canada.

The 1968 Observer of the Year is Steve Craig, Solar
Coordinator and National Solar Coordinator. This year
there was a very close contest between two of our best
observers. Although their fields were as different as
night and day, they were both equally qualified for
Observer of the Year. It was only by reviewing the many
articles submitted by both to Astronotes that a slight
difference aws apparent in the reporting and quality of
the observations.

Dan Brunton and Tom Tothill presented the Merit and
Observer of the Year Awards to Les MacDonald and Steve
Craig respectively, at the 4 Jan 1969 meeting.
Congratulations to you both!
* * * * * * * * * *

WE LEARN BY TRYING

Tom Tothill

Yes, we were there for the graze of Alcyone, and the
weather was clear. Also, there was hardly any wind. But we
didn't get any results except one occultation by Debbie
Wood.

Why?

Well, there were certain difficulties. First, it was
cold - about 10 below. Then we lost two cars by flu at the
last minute, so 5 teams had to go in 3 cars and two of them
found themselves out in the cold. We found it difficult to
stay out for more than 10 minutes at a time and some of
our radios lost so much power as to become inaudible. Our
chosen road, incidentally, was unploughed so we had to
find another. Some of us experienced focusing difficulties
due to water in the eye - so near to freezing that every
blink changed the shape of the water film and its focal
length! Then there was the inevitable car coming by - the
only one of the night - right at central graze...Etc, etc...
A QUANTITATIVE ANALYSIS OF THE HERCULIDS Peter Ryback
In December I gave a brief description of the Herculid
meteor shower based on observations made at Algonquin Radio
Observatory last May. In this issue I shall use those observations
to illustrate how a quantitative analysis of any
shower can be made from limited observations by calculation.
We shall first have to make an assumption about the
rate of fall of meteors from the Herculid radiant, namely
that the rates are symmetrical about the shower's maximum.
In other words, an observer will see x meteors per hour
both n days before and after the date of maximum. (More
extensive observations might show a 'skewed' distribution
but the present assumption is probably valid for shortduration
showers).

Graphically, this symmetry gives rise to a Gaussian
curve, peaking at the maximum and falling off on either
side to approach the base line symmetrically. If the
Gaussian curve is plotted on semi-log paper, it forms an
inverted parabola.

Therefore, a simple way of obtaining the Gaussian
curve appropriate to your observations is to plot the
hourly rates on the log scale against date on the plain
scale, draw the best parabola through the points, pick off
the rates for each date from the parabola, and re-plot
them on ordinary squared paper. This has been done in the
diagrams opposite for the 1968 Herculids, where I had just
three hourly measured rates - 2.7 on May 15/16, 4.7 on May
18/19, and 2.7 on May 25/26. These three points define just
one parabola - if there had been more points I would have
had to excercise some choice and draw a 'best fit' parabola.
The reason for drawing a parabola instead of some kind
of freehand curve is that the Gaussian curve defined by the
parabola has some logical properties in the theory of
probability. For example it accurately predicts the density
of shots on a target and the probability of errors of a
given size. The density of meteors in a meteor stream may
be regarded as analogous to the density of shots on a target.
The area under the Gaussian curve is proportional to
the total number of meteors that would be observed by one
observer on a non-rotating earth. Half of these meteors
fall while the rate exceeds 79.1% of maximum, 68.3% of them
fall while the rate exceeds 60.7% of maximum, and so on -
the details are available in Peirce's Tables.
Results: 1. Date of Maximum = May 20/21
2. Maximum Rate = 5.2 Herculids/hr.
3. Range over ¼ strength = May 13 to May 28
4. whole area = 2330 Herculids
(I must apologise to Peter for changing equations to graphs
-Ed.)