AstroNotes 1970 November Vol: 9 issue 09

NORTH MOUNTAIN OBSERVATORY . OBSERVERS GROUP MEETING - OCT 2 . STARS,EXTENDED OBJECTS, AND PHOTOGRAPHIC SPEED . INTERNATIONAL ASTRONOMICAL YOUTH CAMP, BOLOGNA, ITALY, 1971 . NEWS AND NOTES .

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AstroNotes

The Newsletter of the Ottawa Centre, RASC

Vol. 9, No. 9 November, 1970

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

NORTH MOUNTAIN OBSERVATORY

Tom Tothill

In the past month the Telescope Committee has been
putting a lot of thought into the question of how the
16-inch telescope can be put into the most effective use
by the greatest number of members.
Dr. Lossing found a site next to Springhill Observatory
which was available at $200 a year. However there
was no convenient hydro, and Springhill is now too close
to Ottawa for a really dark sky and this will deteriorate
further when Highway 417 is built some eight miles to the
north of Springhill.
He and I therefore took a drive out into the general
area south and west of Springhill. Attracted by the
names 'North Mountain' and 'South Mountain' on the map,
we took all the back roads in the area and finally found
ourselves at the site where a group of us had attempted
a lunar graze observation one bitterly cold December 30th.
Beside the road was a sign 'For Sale, 60 Acres' and
we found that the owner lived in Hallville only a mile or
two away. His name is Mel Forbes and he is a sand and
gravel merchant as well as being quite a character. He
said he put the land up for sale regularly every three
years but never expected to find a buyer, so he had just
planted the area with red pines as a reforestation project.
However, he thought he could fix us up with a site
on a ten-year lease and drove back with us to a mound of
sand just off the through-road but on a dead-end side
road. A two-wire hydro line crosses the inner end of the
site with a pole on the corner of the property. The rent
would be $150 a year and Mel would grade the site to our
requirements and remove the one large tree free of charge.
We came back to the site the same night with several
others to take a look at the sky glow and surrounding
lights. Two farms a quarter mile to the north have lights
which tend to get lost in the still-obvious Ottawa glow.
To the south-east there is a slight glow from Winchester,
and another in the west from Kemptville. In the south
the glow from Prescott-Ogdensburg is already visible and
would clearly become serious if we went any farther south.
The only big trees are to the north of the site - Mel's
little pines are only a foot high and won' t bother us at
all for at least ten years; they also ensure that there
won't be any cattle in the field surrounding the site.
(Unfortunately, we don't know how to insure against a
certain amount of 'bull' on the site!)
So we decided to stop looking, and told Mel he had
a deal. The next thing was to decide how th e site should
be managed - the lease would have to be signed by several
individuals who would be responsible for the property, and
they in turn would make it available to members of toe
Centre as an observing site for the 16-inch and for private
telescopes. Therefore a group of Trustees has been set
up, consisting of A.E. Covington, W.E. Dey, G.A. Grant,
Dr. P.P. Lossing, and J.T. Tothill ....
The Gods
....who will be responsible for paying the lease,
making toe rules, assigning responsibilities, and managing
the site in general. Annually or as necessary they will
elect a Chairman of Trustees ....
Zeus
....who will take primary responsibility for calling
meetings, organising work among the Trustees, and collecting
and paying out money. The site will be called 'North
Mountain Observatory' because it stands on North Mountain....
Mount Olympus
....whose craggy eminence stands fully seventy five
feet above toe surrounding countryside! Observers should
bring their own oxygen. The telescope will, of course,
be housed in a substantial, vandal-proof building with a
roll-off roof and locked door. It is expected that the
most frequent users of the site will be our most active
younger members. Once they are fully checked out on the
telescope and its accessories they will move into the class
of Key-Men ....
The Angels
....and be given a key to the premises so that they
can use the telescope any time they want. This will apply
to all members who are over (say) 16 years old. There will
be an annual charge for keys, adjusted so that the annual
income to the site is about equal to expenses. It is
clear that another group of members exists - those who
would only pay occasional visits to the site ....
Mortals
....and might well need help in using the equipment.
We think it would be appropriate if they paid a dollar a
visit until they have contributed $5, good for the rest of
the year. Naturally, they would have to arrange to go
with a Key-Man to get in. Finally, there is that class of
people ....
Hoi Polloi
....who are not interested in the wonders of the
heavens, couldn't care less about astronomy, and are not
even aware that the finest telescope within 200 miles will
shortly be available on one of the best sites in Canada.
Fortunately, none of these people are members of the
Ottawa Centre. Aside from the wonders of the heavens
there will be some of The Seven Wonders of the World
connected with the site. The observatory will be 12 x 12
feet inside, leaving room for members to store their
telescopes. The 160 x 65 ft site will have ample room for
members to build permanent mounts outside ....
The Pyramids
....to save carting everything to and from Ottawa.
The size of the observatory is governed by the size of
a building ....
The Temple of Diana
....(Goddess of Light - and Heat?) which we have on
long loan from NRC's Goth Hill Observatory, now being
- 4-
dismantled. The building is 12 x 12 ft inside, insulated,
wired, and with electric heating. It has a flat roof and
a space for a ventilator in the roof. We intend to leave
a space of about 14 ft between the buildings and support
the ends of the rails for the roll-off roof of the observatory
on the building. The building simply rests on
concrete blocks and can be jacked up as necessary to
maintain rail alignment. When the observatory is in use
the roll-off roof covers the gap between the buildings
and we won't have to clear snow from either roof. Also
on long loan from NRC is a privy of a delicate shade of
green to blend with the countryside. The soil is almost
pure sand and no problems of drainage are foreseen.
The building is jacked up at Goth Hill, ready to
move, at the time of going to press - thanks to several
energetic work gangs. Also, the site has been graded,
our side road has been widened and gravelled for a parking
area, and a generous scoop has been taken out of the bank
to site the building in. It is expected that ....
The Colossus of Roads
....will either plough the side road or an extra
width of the through-road for winter parking. The main
objective just now is to get the foundations for the
observatory poured before freeze-up - otherwise we will
have to wait till April or May, and the telescope will
be ready long before that. This may also be a good time
to seed the top of the mound with grass to give it an
early start towards becoming ....
The Hanging Gardens of Babylon
....in the Spring. Rest assured that any half-decent
weekend from now on is a work weekend. Call any Trustee
for details and anyone with a car for a ride down. Finally,
the only wonder comparable with ....
The Pharos of Alexandria
....is a farm light about two miles away to the southeast
which is only partially hidden by the trees. Readers
who by now are wondering just how I am going to work ....
The Tomb of Mausolus
....into this article, and that Seventh Wonder of the
ancient world ....
The Statue of Jupiter Olympus
....can stop wondering. I just did.

OBSERVERS GROUP MEETING - OCT 2

Sylvia Wake

Rick Lavery chaired this meeting which had 42 people
in attendance.
Dr. Lossing explained all about the proposed site for
the 16", including such things as the electricity bill and
the tree. The scheme had been discussed by Council the
previous night and been approved with a recommendation
that the drawing up of the lease should be seen over by a
lawyer, and the telescope and observatory would be insured
by the Centre against telescope-nappers and the FLQ. It
had been left to the Annual Meeting to decide whether the
Centre should make an annual grant towards the expenses of
the site.
After discussion of the site we were shown an interesting
geophysical movie (at an astronomical meeting?). It
explained the external and internal forces acting upon the
earth to create such phenomena as aurora and magnetism.
Ken Hewitt-White mentioned that Comet Abe had reached
a maximum magnitude of 5.7 around Sept 11. Later we were
shown a slide of the comet taken by the Schmidt at the
Quiet Site.
Doug Beaton our Planetary coordinator came forth to
show superb slides of the moon and one of Jupiter. The
moon slides were negatives but looked almost the same as
positives - proof that whatever you do to distort the moon
it's still only the moon.
Rick Lavery explained that National. Council had deleted
the National Coordinator system and initiated instead
Committees of Consultants in each field. He also stated
his intention of getting the variable star program on its
feet again.
Next Ken quizzed us ... what do we do with the result
of all our hours of freezing and fighting mosquitoes?
What do we do with 6000 meteors and 10,000 sightings?
Throw them out? NO!! Answer: give them to a group of
Americans who can and will use them.
Allen Miller wouldn't mind having a few deep sky
observations. Maybe you just feel outdone by the beautiful
drawings he showed last meeting. Incredible!
Finally Dr. Lossing showed some magnificent colour
slides of Milky Way areas - absolutely unbelievable!
* * * * * * * * * * * ****
"... as every researcher just cut of college knows,
scientists of over fifty are good for nothing but board
meetings, and should at all costs be kept out of the
laboratory!"
-A. Clarke
* * * * * * * *
Oh, well; one good year left.
-E d .(49)
Confucius Say:
Boards so-called because of knots and splinters.
For Sale: Elephant (White) Robert Dick
722-5809
I'm selling my white elephant. The White Elephant
is the white metal mount at the Quiet Site.
The mount is sturdy and is on one of the famous
Hewitt-White cement footings. Machined by myself, it has
very easy movement on the polar axis but Dec bearings and
housing must be replaced. Asking $30 - to finance 12".

STARS,EXTENDED OBJECTS, AND PHOTOGRAPHIC SPEED

Fred Lossing

Statements in reference books about the difference
between the photographic "speed” for stars and for extended
objects such as planets and nebulae are usually pretty
unsatisfactory. They generally say that for extended
objects the speed of a given lens or mirror follows the
usual camera rule that speed is proportional to (f/ratio)
and therefore f/2.0 is twice as fast as f/3.5, f/1.4 twice
as fast as f/2.0, and so on.
Then they say that this rule does not hold for point
sources such as stars, for which somehow the speed depends
instead on the diameter of the lens rather than the f/ratio.
At this point, just then your curiosity has been aroused,
they mumble something about the whole subject being too
boring or difficult, so don’t bother your pointy little
heads about it.
It is possible to understand this difference between
point sources and extended objects with a minimum of difficulty
and, hopefully, boredom. Let us think of a lens or
mirror receiving light on its surface from a distant object
and concentrating it into an image. The "light-concentrating
power" or "flux-gain" of the mirror will be proportional
to the ratio: area of mirror/area of image.
The area of mirror is of course proportional to the
square of the aperture D. For an extended or non-point
object, the diameter of the image is proportional to the
focal length F. So the "flux-gain" is proportional to
D2/F2, that is, the usual (f/ratio)2. Therefore, for
extended objects, all systems with a given f/ratio will
give equal photographic speeds, regardless of aperture.
A f/5, 35-mm camera, for instance, is just as fast
photographically as a f/5, 16-in (or 200-in) mirror. This
is a factor to bear in mind when planning photography with
our 16-in telescope. Even if it is big, it is still only
f/5 when it comes to photographing extended objects. The
saving grace is, of course, that the image is much larger.
Now, what is the "flux-gain" for stars? For point
sources it is again: area of mirror/area of image. But
for stars the image it a diffraction spot, whose diameter
is proportional to F/D and not to F only. So the "fluxgain”
becomes proportional to D2/(F/D)2 or ( D / F ) 2x D2,
which is (f/ratio) x D2. This is equal to the "flux-gain"
for extended objects, multiplied by the square of the
aperture. It is an stars that the large aperture really
pays off.
For example, our 16-in mirror will have a speed
advantage (for stars) over a one-inch diameter camera lens
(of the same f/ratio) of 162 to 12, a factor of 256. For
a given exposure, the 16-in will record stars which are
fainter by 2.5 log 256 or 6.02 magnitudes.
Another consequence of this aperture - f/ratio business
is that although two photographs taken with different
apertures at different exposures and f/ratios may happen
to show identical star-field intensities, the one taken at
the lower f/ratio will emphasise any nebulosity present in
the field. While this is an advantage for photographing
nebulae, it is a disadvantage for recording faint stars.
After all, the sky is itself an extended luminous object,
and it follows that at low f/ratios, sky-fogging (i.e.
"nebulosity") will set in before faint stars can be
recorded. The practical limiting photographic magnitude
is therefore increased as one goes from f/2 to f/5 and
higher, without change in aperture.
For those readers who are still here, one question:
What will the "flux-gain” be for M-13? In focus, a globular
cluster is a collection of points. Slightly out of
focus, or unresolved, it is an extended object. So, naturally,
the "flux-gain" will be — ah — let me see —
mumble, mumble.
**** * * * * * ***** * * *
The "Lossing Paradox” could easily become famous! We
invite further contributions towards solving it. If I may
mumble a bit, it would be to say that seeing, transparency,
film emulsion, and guiding errors come into the picture
(quite literally). Seeing and guiding spread the image,
the emulsion adds a further halo around that, and haze (or
lack of transparency) may spread a blueish foreground
across the picture by preferential back-scattering of the
blue part of city lights, while transmitting only the
redder nebulosities and faint stars. -Ed.

INTERNATIONAL ASTRONOMICAL YOUTH CAMP, BOLOGNA, ITALY, 1971

We are indebted to Dr. Luigi Baldinelli, President of
the International Union of Amateur Astronomers, for the
following information:

Following the resounding success of the previous camps
in Germany, it has been decided to hold a further one.
This will take place from 28th July to 11th August,
1971 in Italy. It will be organized by the A.A.B. (Associazione
Astroflli Bolognensi) and the U.A.I. (Unione Astrofill
Italiani), under the auspices of the I.U.A.A. (International
Union of Amateur Astronomers), whose President,
Dr. Luigi Baldinelli, will be general director.
The camp will be a meeting of youths of every nationality
who are interested in astronomy from a practical point
of view, and it will provide an opportunity for an exchange
of ideas and experiences.
The work that will be carried out in the camp will
include lectures, discussions, and astronomical observations.
English and French will be official languages of the
camp. The participants will have at their disposal complete
instruments, a dark room, a library, etc.
The total price will be no more than $35.00
For further information please write, as soon as possible
since the number of participants will be limited, to
the General Secretary at this address:
I.U.A.A. (International Union of Amateur Astronomers)
40121 BOLOGNA
piazza dei Martiri 1
ITALY

Please note that early applications are of the utmost
importance.
North Mountain Observatory - a present visualization.

NEWS AND NOTES

Dr. D.R. McDiarmid addressed the Centre on Oct 14,
describing recent studies of the aurora in the visual,
radio, and x-ray frequencies.

Dr. Gillieson reminded Council that he had only
agreed to serve one year as President of the Centre and
therefore elections would be necessary this year.
Dr. Halliday has requested that he be replaced as
Ottawa Centre representative on National Council.
The Ottawa Centre will get an extra representative
on National Council if the membership goes over 200.