AstroNotes 1969 May Vol: 8 issue 05

EDITORIAL . Variable Stars Project . BUILDING AN OBSERVATORY . Perspective: . MARCH MEETING OF THE OTTAWA CENTRE . LAST MONTH'S OBSERVERS GROUP MEETING . For Sale . MAY MEETINGS

Pages: 

12

Download PDF version: 

ASTRONOTES      Vol. 8, No. 5           May, 1969

Editor: Tom Tothill 22 Delong Drive, Ottawa 9
Addresses: Howard Harris 620 Keenan Ave, Ottawa 13
Circulation: Ted Bean 399 McLeod St, Ottawa 4

EDITORIAL

The Observers Group's desire to see the establishment
of a National News Letter may be brought nearer to realisation
at the General Assembly. A questionnaire on the subject
sent out to all Centres by your Editor has had a favourable
response from all who have replied to date. Evidently the
need for such a periodical is well recognised across Canada.
The Ottawa Centre's request for meeting facilities to
discuss the subject in more detail at the General Assembly
appears to have got lost along the way, however, since no
such item appears in the material so far received concerning
the proceedings. Instead there is an item for the
discussion of Centre News Letters "requested by several
Centres". In Ottawa we know nothing of this item and are
wondering if this is a misprint for the item we have
requested. In any case, we are arranging to hold two
meetings of the representatives of the different Centres
concerning the National News Letter. The first will be
an informal "get acquainted" meeting right after the
Planetarium show on the Friday night. The second will be
the business meeting, to be held as a 'dutch treat' lunch
on the Saturday, where we would hope to arrive at a
concensus on specific proposals to put before the Annual
Meeting at 2 p.m. Obviously, if we can't reach full
agreement at the lunch the whole project will stew for
yet another year, and if we allow the subject to be put
in with the Educational and Cultural Committee discussions
at 3 p.m. - after the Annual Meeting, it will suffer the
same fate.

In our view, the Society could take on an altogether
new lease of life if it had a NNL (the neatest title
suggested so far is FOCUS) giving prompt information on
who is doing what in the different Centres, making people
feel they belong to a wider organisation, stimulating
observing programmes of wider scope and participation,
and generally exchanging ideas on a genuinely open basis.
Whatever it is called, the National News Letter
would indeed act as a focus for the Society. Support it.
HAPPY BIRTHDAY. ASTRO-NOTES! Dan Brunton
Six and a half years ago a ‘brave new world’ was
opened up to the amateur astronomers in Ottawa. On
December 1, 1962 the first issue of Astro-Notes was
produced and thus commenced what I consider (admittedly,
with bias) to be the best amateur astronomical publication
in Canada. This issue is our 50th - a truly golden event!
The original credit for this experiment goes to
George P. Brunton who first recognised the pathetic
communications that surrounded us all, and who had the
foresight to push for the establishment of a Centre newsletter.
With the assistance of then-Chairman Bill Dey,
he got acceptance of the idea and Astro-Notes was born.
Since then we have had five other editors - Howard
Harris, Frank Evraire, Dan Brunton, Peter MacKinnon and
our present (excellent) editor, Tom Tothill.
The Observers Group has had its ups and downs in the
past six years and this is reflected in Astro-Notes - and
that's the beauty of it! For the first time, we could
look back and see just what did happen in previous years.
Astro-Notes has proved to be a very successful log
of activities, to say nothing of its value as an informative,
instructive publication for the benefit of our
members.

Highlights? Well, how about the excellent Deep Sky
series carried on for so long by Col. John Stairs, or Tom
Tothill's Centennial Edition in '67, or the 'White Spot’
writeup by the Solar group in '68, and so on?
Yes, when other groups were struggling to stay alive,
we were able to produce a publication of lasting value
and interest. It would seem to me that its existence is
one of the best reasons for the continuing strength of
the Observers Group.

* * * * * * * * * * * *
This might be a good time to thank the many people
who have contributed articles, time, and effort to the
production of Astronotes. (Note, by the way, that like
Shakespeare we spell our name in various ways!). Perhaps
the Editor has more fun than the unsung heroes who fold,
staple, and address it, and get it to the Post Office,
but they do it cheerfully and well.

Variable Stars Project

This summer, I would like to introduce a project to
the Observers Group that can be carried out whether you
are at camp, on the west coast, on the east coast, in Death
Valley, on top of the Rockies, or just in beautiful downtown
Ottawa. All you need are binoculars, which most
people have anyway, and an AAVSO chart and report form
which I can provide.

Through the kindness of the Ottawa Council I was
granted to pay for 20 AAVSO charts. Each chart shows a
field in the constellation Hercules quite close to M13.
So, if you can find M13 in binoculars this project should
be a snap. There are not one, but three variables to
observe; G Herc , X Herc, and RR Cor Bor.
G Herculis, the brightest, is said to range between
4.4 and 6.0 with a period of 80 days. This statement,
which appears at the top of the sky chart, is completely
inaccurate, and we should try and pinpoint the variation
and period this summer. Being the brightest, I hope it
will be observed the most, and a good record of its variation
will be the key. This variable should be observed
once a week.

The second brightest variable, X Herculis, is supposed
to have a range of 6.5 to 7.3 and an even 100-day period.
It doesn't!! I have observed variations from 6.0 to 7.5
and only an 80-day cycle, but I can't be too sure of the
period from my scanty observations. So again, more work
needs to be done here; observations should again be once
a week.

RR Corona Borealis is the dimmest of the variables,
having a range from 7.2 to 8.4 with a period of 60 days.
This variable should be observed every 5 days, as the
change in brightness is swift, and the time of minimum
and maximum brightness very difficult for an irregular
observer (like me) to observe. This variable appears to
be semi-regular - and I would like to see if it really is.
Now that I have given you a resume of the data the
AAVSO has for these stars you see how incomplete they are.
This is the reason for suggesting this as a group project
so that a complete light curve can be drawn. There is
also scientific value that can be obtained from these
observations, and these will be dealt with upon completion
of the project.

STOP PRESS!! The sixteen-inch mirror blank has arrived in Toronto!
As you may have guessed, the primary reason for
initiating the project is to 'whip up' some interest in
observational astronomy, i.e. variable star observing.
I must state quite strongly that this project is not for
my benefit but for your astronomical benefit.
I'll be giving a short talk on making variable star
estimates at the next meeting. If you can't attend* phone
me at 828-8213 or write to me at:
1227 Morrison Drive
Ottawa 6, Ontario.
* * * * * * * * * * * * * *

BUILDING AN OBSERVATORY

Tom Tothill

In our climate* where the cold season is interrupted
only by the mosquito season* it takes more intestinal
fortitude than I possess to carry my telescope out into
the garden* set it up* and then stay long enough to do
some useful observing. So the primary objects in the
design of my observatory were to provide a light-tight,
mosquito-proof, and slightly warmable enclosure as well
as a permanent solid mount for the telescope.
The base was finished last Fall and covered up for
the winter. It consists of two separate parts: the
pylon for the telescope consists of three columns of
concrete tied together by cross members at ground level.
They go down three feet into the ground and project a
foot above ground. On the flat tops of these three
columns the legs of the telescope rest, and will have
permanent locating plates so that I can still pack the
telescope into the car for grazes or star nights, and
then put it back without readjustment. Surrounding the
pylons is a separate ring of reinforced concrete, going
only two feet into the ground and a foot above. This
ring carries the fixed observing floor of 3/4-inch
plywood carried on 2 x 6 joists. The floor has holes
cut out of it through which the tops of the pylons just
project, but they do not touch it.

The outside of the ring is finished very circular
and drops down to a step carefully parged while it was
wet to give a level* circular surface an inch or two
above ground level to carry the wheels of the rotatable
building* eight in number plus four smaller guide wheels
running on the vertical surface.

Although the conventional notion of an observatory
is a hemispherical dome, I rejected this style from the
start. Not only is it difficult to construct - it is
also not a useful shape. One needs some flat walls to
hang maps and bookshelves on and maybe project the sun.
Mine is the shape of a Nissen or Quonsett hut, as long
as it is wide - 10 ft x 10 ft. A full size door is in
one of the flat ends, and the slit cover rolls up over
the curved surface in the middle, opening past the zenith.
As the slit cover rolls up, a roller blind unwinds
to cover up all but the part of the slit needed for the
telescope. Between the end of the telescope and the slit
there will be a bellows of soft velvet, keeping out light,
bugs, and some of the cold. Weatherstripping along the
sides of the slit cover will seal that too.

The square base of the building has a large circular
hole cut out of it the size of the fixed observing floor
and this too will be weatherstripped to the floor. Thus
I hope to be able to at least take the chill off in winter
with a small radiant heater directed on the observer.
Note that the telescope must be of closed tube design to
take advantage of this system - otherwise the warm air
would rush out through the tube and ruin the seeing. It
is also necessary to insulate the whole building; mine is
of double-wall construction throughout, with three layers
of aluminum foil between.

Current status is that the base with its wheels, the
two ends, and the two slit rings are finished ready to
assemble, but before that is possible I have to make the
slit cover. Then will come a frantic weekend when we put
it all up, lay on the curved roof, and try to get it
painted before the next deluge!
Cross Section:
0.4" = One foot

Perspective:

March 29/30 was the first clear night since the
occultation of the Pleiades a week earlier and I was preparing
to go out and make some variable star estimates when
my preparations were disrupted by the ringing of the telephone.
The breathless caller (Ken Hewitt-White of course!!)
asked me to make an estimate of RX Leporis, an irregular
binocular variable he had been following all winter. Despite
the retarding influences of a pair of crutches I made
it out in less than 5 minutes and made an estimate of 5.3
Now RX Leporis is never supposed to get brighter than
5.9, according to AAVSO data, but this night it was half a
magnitude brighter. I phoned Ken and informed him of my
estimate which turned out to agree quite closely with his.
We decided we would wait until the next night to see if it
was going to brighten any more before sending off a telegram
to the proper authorities.

For some strange reason it was clear the next night
(a flaw in Murphy's Law?) but RX Leporis remained at
approximately 5.3. So unfortunately Nova Hewitt-White
didn't materialise, but as of the April meeting the variable
was still about magnitude 5.3

* * * * * * * * * * * *

MARCH MEETING OF THE OTTAWA CENTRE

The Centre met on the 27th to hear L.R.McNarry of the
Radio and Electrical Engineering Division of the National
Research Council.
His subject was "Solar Radio Emission and its Polarisation"
as measured at the Algonquin Radio Observatory
over the past several years, a field in which Mr. McNarry
is a pioneer.
The talk was illustrated by slides of the equipment
devised and the results obtained, and was followed by a
discussion.
The President read a letter from Dr. Heard, the
National Treasurer of the Society, indicating the need
for an increase in membership fees to halt the current
losses being sustained by the Society, and the proposed
increase to $5.00 for students and $10.00 for adults was
approved without dissent.
For a number of years, there has been very little
effort on the part of the Observers Group to teach new
members the basic points of observational astronomy.
How can a new member observe something if he doesn’t
know where in the sky to find it? I feel the more experienced
members have an obligation to provide these basic
necessities of astronomy. So, this summer I would like
to try a series of constellation "courses" to familiarise
our new members with the constellations and the magnitude
system. I use "course" only to show that it is an organised
program, and does not involve tests and extra work.
Starting June 6 will be the program for adult members
(before they're away on holiday) and we will meet three
times, once a weekend on whichever night happens to be
clear. If you are interested, call me at 828-8213.
Beginning July 4 will be the program for student
members and the same schedule as for the adults will
apply. Again, give me a call if you are interested.
Note: When the program coincides with a star night, the
classes will be held at the site of the star night.
If the above dates don't suit you, but you are
interested, give me a call anyway.
RESULTS GUARANTEED

* * * * * * * * * * * *

LAST MONTH'S OBSERVERS GROUP MEETING

Where's Chris?

After the usual blast re Solar observing, Steve Craig
showed beautiful drawings of the recent large sunspot
group and its changes from day to day. Allen Miller had
superlative colour renderings of Jupiter showing the
extremely black centre recently apparent in the Great
Red Spot, most of which is whitish, and the dark blobs
farther east on the North Equatorial Belt. Rick Lavery
reported on RX Leporis (see p. 7) and his summer courses
(above). The observational period was concluded by Tom
Tothill with an account of the many complicated calculations
involved in translating lunar occultation timings
into lunar limb and positional corrections. The Pleiades
total for Ottawa, he reported, was 179 timings.

The main talk, given by Bill Dey, was on the Dall-
Kirkham telescopes that he and Dr. Lossing are building.
IDEAS ON A SKELETON TUBE REFLECTOR Ken Hewitt-White
Recently this person has been undertaking a remodelling
job on his 8-inch Newtonian. While rummaging through
the cellar for old washer parts, I came across a conspicuously
old (1935?) wheel hub hidden behind the oil burner
under an endless assortment of trash. The hub was rusted
and caked with dust but otherwise in reasonable condition.
Closer inspection revealed an interesting axle and bolt
hole arrangement. I soon found that my 8-inch mirror cell
could fit snugly in the centre area of the hub and that
with only minor alterations the adjusting wing nuts could
be passed through the bolt holes and fastened behind. The
whole assembly would be wonderfully secure and easy to
operate. A glance at the drawing shows how my thoughts
proceeded from there.

The short arrangement of crossed spokes on the hub
accepted 3/4-inch threaded piping very securely and thus
several lengths could be extended where an 'observer cage'
could be attached at the end. This would provide an open
tube framework - a questioned structure for some amateurs.
It is argued that difficulties arise with wind currents
but I would think that a closed tube would only compound
the velocity currents trapped in a closed area.

This particular framework is easy to build, too;
simply push in and lock. The cage need not be more than
a plywood 'box' fitted snugly over the pipe framework. As
the cell end is quite heavy (24 lbs with an 8" mirror) a
guide scope or camera system could easily be attached to
the flat face of the cage to even the balance.

The hub can accept mirrors up to 16" in diameter with
only minor modifications of the framework attachments.
For my purposes, securing the tube to a mount would come by
means of a suitably welded flange on the edge of the hub.
The most attractive point in favour of this arrangement is
the fact that the whole system is astrographic without
alteration of my present German mount system. The telescope
would be ideal for deep sky sessions where moving
from one part of the sky to another occurs often. Frequent
reversing of the tube to opposite sides of the mount only
inhibits exploring opposite ends of the sky in frequent
succession.

On the whole, the project is a cheap one, fine for
the budget-minded amateur (me!), sturdy in build, and
uncomplicated for the mechanical simpleton (me again).
* * * * * * * * * * * *

For Sale

at 8-inch mirror, ground and partly polished to
f/10. $12.00 .
-Allan Millar, 224-1098.

MAY MEETINGS

Star Night Friday, May 9. (If cloudy, Saturday).
Meet at Dominion Observatory, 8 p.m.
Drive to Quiet Site. Visitors welcome.
Main Meeting Tuesday, May 13. Conducted by Observers
Group. Geophysical Library, Dominion
Observatory, 8 p.m.

General Assembly McLaughlin Planetarium, Toronto, May 16-19
For transportation, contact Dr. Lossing.