AstroNotes 1971 February Vol: 10 issue 02

LUNAR ECLIPSE. FEB 9-10 . ANNOUNCING: A GRAZE . VARIABLE STARS . METEORS 1970 - THE FINAL REPORT . WHY IS THE SKY DARK AT NIGHT? . DEEP SKY . AWARDS PRESENTATIONS - 1970 . LAMENT FROM THE QUIET SITE .

Pages: 

12

Download PDF version: 

AstroNotes

The Newsletter of the Ottawa Centre, RASC

Vol. 10, No. 2 February, 1971

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


LUNAR ECLIPSE. FEB 9-10

John Conville

A lunar eclipse provides an opportunity to measure the size and general condition of the earth's atmosphere. To determine this, three types of observation are needed;
those of colour and brightness and those of shadow contact times. The four contact times of the umbra should be measured as well as the mid-crater contact times of the following:
Grimaldi, Aristarchus, Kepler, Copernicus, Pytheas, Timocharis,
Tycho, Plato, Aristoteles, Eudoxus, Manilius, Menelaus,
Plinius, Taruntius, and Proclus.

The timings should be accurate to 0.1 of a minute. The Observer's Page in Sky & Telescope, January Issue, has a photo showing the crater positions and an article which describes possible observations in greater detail.

There are also three occultations of interest. Information about them was supplied by Rick Lavery.
Ingress Egress
Star Mag. PA Time. UT PA Time. UT
ZC 9630 8.8 108 06:26 53 07:32
ZC 9655 7.6 96 08:07 0 09: 00
zc 9656 8.7 92 08:09 4 08:58

Astropun: Is a clock made for the moon a Luni-tick?


ANNOUNCING: A GRAZE

STARRING: ZC 2383 (Tau Scorpii) 2.9 Magnitude.
CURTAIN TIME: Approx 04:30 EST, Feb 19(Friday morning).
THEATRE: Approx 3.5 miles SW of Stittsville.*
NO CROWDING: A seat every tenth of a mile,
THIS IS A ONE NIGHT STAND AND ONE NIGHT ONLY!!!!!!!
* Especially for those who are "just beyond the fringe".
Phone me: 733-8299


VARIABLE STARS

Rick Lavery

It seems that quite a few people saw my ramblings in the variable star report and have asked me to expand on what I was planning. Unfortunately, I will not be able to
say: Well, we are going to observe this star, and that star, and maybe someone else will make timed estimates of another star. The reason is obvious. Until we find out the exact optical capabilities of the 16-inch, that is to say its limiting magnitude, we cannot talk about observations of specific stars.

However, once we find out that the telescope has a LM of 15.0, for instance, we should concentrate on stars that have minimas around this magnitude. This will ensure
that we are using the telescope to the maximum of its capability.

So, once the LM is known we will start on some very simple group projects. For example, we will try and observe a few flare stars (like UV Ceti) and recurrent
novae (like RS Ophiuchus). Then I hope that some of our younger members who are used to all-night observing sessions might find themselves interested in eclipsing binaries. Unfortunately this is one field where very little work has been done, because of the amount of cloud-free time (one night) required. Daring the one night the observer may make as many as 100 observations, which are timed accurately.

Why should eclipsing binaries be interesting objects to observe? Well, it seems from the initial results that the periods of these systems change significantly. A number of astronomers have ventured to say that there is some sort of mass exchange going on. But is this plausible? The only way we will know is to study these systems over many years, and - you never know - our observations may help in some way to solve the problem.

* * * * * * * * * * * * *
The 'Lavery Special' is a delivery service bringing last-minute articles to Astronotes. It is very much
appreciated.
-Ed.
* * * * * * * * * * * * *
This month we either had to squeeze or let you suffer three pages of the Editor. You won - we squose. -Ed.


METEORS 1970 - THE FINAL REPORT

Ken Hewitt-White

A most successful year of observations has ended for the Ottawa #4 meteor group. In fact, in its nine year history we haven't seen a better one. In 1970, 17 people
observed on 60 nights gathering in 8740 sightings of 6608 meteors, 435 of which were plotted. The best individual effort drew 1630 meteors in 182 hours of observing. Every one of those figures is a new record for the Ottawa #4 team.

The data is now being reduced and reports are being prepared for the I.U.A.A., A.M.S., N.R.C. and our own L.I.B.R.A.R.Y. A computer programme has been nearly
completely debugged and we should be giving some Carleton computer indigestion in very short order. (Has anybody any computer cards they would like to donate? We need only 18,200 more to complete our program).

Below are the final figures for 1970.
Name Nights 10-min per. Meteors
Brennan, Peter 3 50 64
Brennan, Rick 2 27 71
Conville, John 11 195 540
Craig, Steve 21 359 836
Davis, Lindsay 6 100 125
Dawm, Paul 2 76 138
Dick, Robert 20 350 666
Hache, John 6 113 379
Hall, Cathy 26 499 866
Hewitt-White, Ken 58 1095 1630
Lavery, Rick 5 83 198
MacDonald, Les 27 364 573
MacKinnon, Pete 4 42 199
Martin, Chris 17 347 630
Miller, Allen 16 277 485
Murphy, X 305 16470 7
Paterson, Dave 25 413 138
Wake, Sylvia 10 198 503
* * * * * * * * * * * * *
And Murphy hasn't even paid his dues. -Ed.

The winner, for 1970, of the Variable Star Award is Ken Hewitt-White. This is the second year in a row that Ken has won the award. Congratulations, Ken!
The final standings, except for a very few outstanding observations, are:

Standing Observer Total

1 Ken Hewitt-White 686
2 Brian Bartlow 321
3 Jon Buchanan 249
4 Rick Lavery 243
5 Chris Martin 224
6 Allen Miller 198
7 Robert Dick 150
8 John F. Conville 54
9 Barry Matthews 32
10 John Rowlandson (Trenton) 31
11 John Hache 18
12 Sylvia Wake 7
13 Peter Schlatter (Brockville) 3 2216! !

I would like to thank all the other observers who took the time and effort (and braved the cold and mosquitos etc.) to make this program a success again this year. I would encourage those observers with observations in the 3-figure range to join the AAVSO or at least start sending your observations to them. Report forms are available from me.

Please keep in mind that only observations of the Hercules and Orion variables will count towards the 1971 totals and the Variable Star Award.
Be number 1 in '71.


WHY IS THE SKY DARK AT NIGHT?

Peter MacKinnon

When one looks out into the night sky there appears a myriad of stars of various magnitudes; some appear very bright, others less so, and still others very faint. Furthermore the greatest number of stars appear to be fainter.

One could account for this phenomenon by assuming that the stars are at various distances from earth. Thus, the brighter stars are nearer and the faintest are  farthest. This would explain the variation in the brightness of the stars as well as the fact that there are fewer bright stars than faint stars for there is more space farther away than nearby. What of the stars at even greater distances, far enough away that neither eye nor instrument can distinguish them? The question arises whether this star background could possibly create a homogeneous illumination of the night sky. This is the question that the German astronomer Olbers asked in 1826.

To answer this question Olbers made several assumptions. He first assumed that the distant regions of the universe would be very much like our local region. Thus stars would be found there and the distance between them would be similar to the distances between stars in our local region. Furthermore he assumed that the stars with their intrinsic brightness would create a combined average brightness which is similar to that of the stars within our local region. This implies that our place in space is not special - what we see is but a typical view of the universe. Olbers further assumed that time played no different a role in remote space than it does in our local region. The next assumption was that the laws of physics apply everywhere in the universe regardless of time. The final assumption was that the universe was static.

With these four assumptions in mind the background illumination of the sky can be found. Consider a shell of radius R and thickness H. We let H be very much smaller
than R. The shell is taken to be very large so that many stars can be found within the shell. In order to calculate the number of stars in the shell we must first know the
volume of the shell. If the surface area of the shell is 4 pi R2 then the volume can be shown to be 4 pi R2 H. Shell with its content of stars Let N be the number of stars per unit volume. The number of stars in the shell of volume 4 pi R2 H is 4 pi R2 H N. We then ask how much light all the stars in this shell will emit.

First we let the average light emitted by a single
star be L. Thus the amount of light emitted by all the
stars in the shell will be 4 pi R2 H N L. This gives the
amount of light the stars send out; however we wish to find
the amount of light we receive. By considering a star in
the shell at a distance R, then after time T (the time
required for the light of the star to reach us) the light
will have travelled a distance R and spread out over a
surface 4 pi R2. Thus for each star in the shell we
receive but 1/4 pi R2 of its light per unit aperture area
(e.g. per square mile of aperture if R is in miles, but R
could be measured in 'eyeballs' without affecting the
argument). For all the stars in the shell we therefore
receive light amounting to H N L through unit aperture area.
This is very interesting for it shows us that the amount
of light we receive is independent of the radius of the
shell; hence from each of any number of shells of equal
thickness we receive the same amount of light. If we keep
adding on additional shells the amount of light received
will increase without bound. Therefore we should be
receiving an infinite amount of light from all the shells
which go out to infinity.
But there is one fact we must account for. As we
superimpose shells we will eventually find the celestial
sphere completely papered over with star discs whereby
the light from stars at a greater distance will be blocked.
This fact prevents the amount of light from going to
infinity but it still allows a flood of light equivalent
to 50,000 times the intensity of sunlight when it is at
the zenith. This would create a surface temperature of
10,000 degrees Fahrenheit. Life could not exist!
This remarkable result is not observed in nature
although the argument says it should occur. Olbers
attempted to find a way out by supposing that dark clouds
prevented this great flood of light from reaching us.
This does not work as he found that the temperature of the
dark clouds would eventually rise to the point that they
would radiate their own light which would be proportional
to the amount of light received from the stars behind.
Thus we are posed with one of the greatest paradoxes
of cosmology. Since prediction does not agree with observation
then one or more of the assumptions must be wrong.
If the assumption that the universe is static is dropped and
in its place we assume the universe to be expanding then
the paradox can be explained. It is a well known fact of
physics that as a source of radiation moves away its intensity
decreases. Therefore if the objects in the shells
are moving away hence weakening the light which floods
into the voids of space then indeed the sky can be dark
at night.
In modern terras the stars spoken of by Olbers can be
replaced by the term galaxies,
Olbers' paradox is one of the bases of modern cosmology
and it is an integral part of every hypothesis on the
nature of the cosmos.
* * * * * * * * * * * * *
A knotty problem, for sure, and one that we ought to
be able to explain. The converse seems to be that as soon
as the universe ceases to expand we will fry! Stars are
converting mass to energy which goes out at the speed of
light through space until it hits something, when the
energy is re-radiated at longer wavelengths. Is there a
point where energy is converted back to mass instead of
being re-radiated?
-Ed.


DEEP SKY

Allen Miller

Good Evening, Yes, it's me again except this time
with a twist - that is I am finally fighting the Canadian
winter. I'm staying indoors writing space-fillers like
this and getting you people to do the freezing for me.
As I mentioned at the January meeting, I have a new
and very different program in mind. It consists of drawing,
painting and/or photographing the densely-populated
area of the Coma-Virgo group. Now you might say that’s
all very well but why the heck should I go out and freeze?
I'll try to answer that below.*
Ken and myself have just completed a book on the
summer sky (A Midsummer Night’s Dream), We want to make
another one but in a much different way, I would like
drawings, paintings or photographs of the galaxies as
"seen" by different scopes and persons. If they are neat
but realistic we will probably use them - in that case
the artist's name is also shown. Up to 15 drawings per
person will be reproduced, I might also add at this
point that a description along with scope size and power
is also very useful.
At the February meeting I will have some individual
program sheets made up to aid you in your tricky task.
* * * * * * * * * * * * *
* For more information turn to page 22.
* * * * * * * * * * * * *
THIS SPACE IS FOR YOUR VERBATIM NOTES WHILE FREEZING:


AWARDS PRESENTATIONS - 1970

Ken Hewitt-White
What is an Observer of the Year? We look to a 1967
Astronotes article for the answers
"The distinction Observer of the Year is, in the
words of the original motion, 'awarded annually to the
member of the Observers Group who has contributed most to
the advancement of astronomy in the group'. The purpose
of the award ... is to stimulate keener interest in
observational astronomy among members of the group ...
The selection is based primarily on actual observations ...
Construction of a useful piece of apparatus is also a
valuable contribution ... This includes communication of
the results to the proper authorities."
Who satisfied these conditions for 1970? Allen
Miller. Allen has promoted much interest in the group
this past year through the displaying of his many slides
and the presentation of talks at the various Observers
Group meetings. Allen has made observations in nearly
every field including special efforts in Deep-Sky and
Meteors. He has constructed some pretty useful apparatus,
too. At the Quiet Site he built a communications panel
in the van which has aided immensely in the recording of
meteor data through the year. In March he completed a
six-inch Gregorian telescope and seven months later
polished off the optics for a ten-inch Newtonian-Cassegrain.
Results? Oh yes indeedy: comet shots, deep-sky paintings
and star photos. When the time came to report something
big, he did. As was the case when he suspected a nova in
M5 and reported the find to several observatories.
There is no doubt that we have a worthy recipient
for the Observer of the Year 1970. Congratulations, Allen,
for a fine year of observational activities!
From that same 1967 article we find another interesting
paragraph:
"It is important to realise that this (observer)
award is not made on a 'Most Valuable Member' basis, and
it does not recognise the useful and time-consuming
administrational and supervisory contributions which some
members have made during the year. Perhaps we need a
second award to take care of our recognition of such
services!"
Well, we have that too. The Merit Award is not for
administrative feats by the current officers (who are
simply expected to produce them) but it does recognise
the outstanding contributions that a member may have
made to the Observers Group over any particular period
of time. Only one fellow has received this award before
and that was Les MacDonald. This year the Awards Committee
of Ed MacKay, Ken Perrins and myself had no other choice
but to award the 1970 Merit Award to Fred Lossing when
they stacked up the forty-odd other members against him
and saw that he still pooled more points!
What has Fred done for our group? It would be
impossible to list his many kind deeds in this smalll
space. Suffice to say that without Fred Lossing this
group would be lacking most of the influence that it
enjoys today. In particular he has aided immeasurably
in our 16-inch telescope project giving both wisdom and
an awful lot of elbow grease. For many of us, he is
someone to look up to. For all of us he is someone to
admire and thank for the many selfless hours he has put
into making our Observers Group such a fantastic organization.
Thank you so much, Fred Lossing; you are truly
worthy of the 1970 Merit Award. The question only remains
whether said award is worthy of you!
* * * * * * * * * * * * *


LAMENT FROM THE QUIET SITE

Chris Martin

Where have all the observers gone,
long time passing?
Where have all the observers gone,
long time ago?
Where have all the observers gone?
Gone to North Mountain, every one.
When will they ever learn?
When will they e-e-ver learn?
Tunes "Where Have All the Flowers Gone?"
* * * * * * * * * * * * *
How about the Fruits? -Ed.