AstroNotes 1971 December Vol: 10 issue 10

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AstroNotes

The Newsletter of the Ottawa Centre, RASC

Vol. 10 , No. 10 - December, 1971

Editor:
Addresses;
Circulation;
Tom Tothill
Mary Grey
Ted Bean

PHOTOGRAPHY WITH THE SIXTEEN

22 Delong Drive, K1J 7E6
Dom. Observatory, 994-5474
399 McLeod Street, K2P 1 A 5
Fred Lossing
Now that the Sixteen is operative and the polar axis
aligned reasonably well, the great race is on to try it
out for photography. This can be at prime focus, for deep
sky objects, or eyepiece projection for lunar and planetary
work. Initial attempts have been promising, rather than
successful, and evidently further experience will be needed
to get really good pictures. It is already obvious that a
good guide-scope will be an absolute necessity; relying on
a pre-set RA drive rate and keeping fingers tightly crossed
with regard to possible drift in declination just will not
be good enough.
For prime focus shots Rolf Meier and I (and no doubt
others) have found that a 20 minute exposure gives star
images which consist of four or five dots spread along a
line about 1 mm long on the film. The line is oriented
east-west and is clearly connected with RA following. The
”dot-streak" is caused by two factors: the "streak" comes
from a slightly wrong RA drive rate setting, and the "dots"
come from a periodic back-and-forth error arising from the
engagement of the RA drive worm with the teeth on the large
gear. Steps are under way to get rid of this periodic
error by getting a different type of worm, but this is
going to take some time. Meanwhile, the "streak" can be
reduced by getting an exactly correct drive rate. The
residual streak arising from the periodic error will then
be only 0.25 mm or so in length in the focal plane, and
should be tolerable for prime focus shots.
Eyepiece projection gives a plate scale some 5 to 8
times greater than at prime focus, and good pictures at
exposures over one minute will have to await the new worm
and the installation of a guide-scope, or both. (It is a
case of the early worm getting the bird).
It is surprising how accurately the RA drive rate
must be set to avoid a streak. For the Sixteen, the platescale at the prime focus is calculated as:
Plate scale - 57.3/F = 0 .7 0 o/inch = 100" of arc/mm.
What does this mean in terms of how fast a star
image travels in the film plane? The earth rotates about
1 ° in 4 minutes or 15" of arc per second. The focal plane
image of an equatorial star will therefore take only
100/15 or 6 .7 seconds to move 100 " of arc, thereby making
a streak 1 mm long. A 6.7 second error in HA drive rate
over the duration of the exposure is sufficient to do this.
For an exposure of 20 minutes this only 6.7 seconds in
1200 , or 0.5%; in other words 1 cycle in 3 seconds at
mains frequency. To set the drive rate to this accuracy
or better, allow the drive unit to operate at least 15
minutes to reach ambient temperature before making any
change thought necessary in the rate. (After all, someone
may have spent an hour the previous night getting it just
right!).
A new deep-sky camera is being built, using a f/2.5
12” focal length Aero-Ektar lens loaned to us by courtesy
of Fil Park, This will have a plate scale of 5 °/inch and
will have two backs - one for 4 x 5 film or plates, and
one for 35 mm SLR cameras. It is too heavy to mount per­
manently on the Sixteen, but will be stored at NMO with
its counterweight, ready for temporary mounting on the
declination yoke of the Sixteen. Unmounted, it could
double as a fast meteor camera, if a suitable chopper
attachment were built. With the 12" focal length of this
camera, the temporary problems with the RA drive would be
unnoticeable except for exposures of an hour or more.
LETTERS TO THE EDITOR
Some more poetry (?) for Pow to muse over as he goes
into the roll maneuver:
A mathematician named Klein
Thought the Mobius band was divine.
He said: "If you glue
The edges of two,
You'll get a queer bottle - like mine."
- be suing you.
Grady.Kleiner than most,
-Ed.
* * * * * * * * * * * * *
OBSERVERS GROUP MEETING - NOV 5
Chris Martin
Sixty-three ( 63 !) people attended the meeting, with
Leichtenstein Ravery at the helm.
Nominations were proposed for the December elections
for the new executive and co-ordinatorships.
Jack Horwood got "oohs" and "aahs" when he explained
how one could get CHU off an AM radio for 12 bits and half
an hour's work! (See next issue?)
John Conville told about the “last ditch efforts" to
see the graze of Nov 3. Only 3 saw it; the other 97% of
us were looking at the wrong end of the moon. A master­
piece by Murphy, no less!
Slides of Mars by Ed ter Heijden, showing the amazing
improvement due to superposing two exposures, and infra­
red photos by Al Miller preceeded the main talk of the
evening.
That topic was "The General Principles of Meteor
Observing" given by Ken Hewitt-White, Co-ordinator of that
field, Ken gave comprehensive information on shower rates,
sporadic meteors, meteor photography and much, much more.
Indeed, it was an excellent report on the Meteor Group's
activities for the last five years.
The meeting concluded at 10:35 with coffee and eats
nobly prepared by Stan Mott in Ken Perrins' absence.
* * * * * * * * * * * * *
IT IS AN ENORMOUS PLEASURE !!! ...
... to congratulate Dr. Gerhard Herzberg on being
awarded the Nobel Prize for Chemistry, in recognition of
his outstanding work in the spectroscopy of ions and free
radicals which, though short-lived in the laboratory, could
exist for long periods in space and be identified in
astronomical spectra.CROWDED OUT?
Barry Matthews
Can any member or members devise a plan to aid the
newcomer in developing and improving his enjoyment of the
splendours of the Universe? All it will cost is a little
time. A few ideas I have considered follow:
(1) Formation of a programme to advance the beginning
amateur through the various sections with a prescribed goal
such as becoming an 'accredited observer'.
(2) Re-instigate a Messier race.
( 3 ) Have an up-to-date list of Observers Group
members from whom they can get assistance.
Come on fellows - let's put the "Group" back
"Observers Group".
in
I recently read that "There is a probable link between
the rotation rate of the earth and the activity of the sun"
and speculation that "The San Andreas Fault now overdue for
a major slippage might be triggered by solar activity in
the late '70s or early '80s after the next period of max­
imum solar activity."
* * * * * * * * * * * * *
DR. HALLIDAY'S SEPTEMBER TALK
Dr. Ian Halliday addressed the Centre on Sept 28 on
the subject of the Meteorite Recovery Program in Western
Canada, describing the 12 semi-automatic camera stations
across the Prairies, some of the design problems, and
first results obtained. The search for a seismically-
detected meteorite in B.C. was particularly interesting
but unfortunately unsuccessful. From the November issue
of the Saskatoon Centre News Letter we learn that the
MORP cameras indicated a meteor with a probable mass of
2 kg fell near Nokomis, Sask on Aug 17, breaking into four
pieces, three of which could have fallen. So far, however,
nothing has been found in the area.
* * * * * * * * * * * * *
The above items somehow got missed last month.
-Ed.DON'T MISS SATURN!
Ken Hewitt-White
Saturn came to opposition on Nov 25. That means that
the ringed planet will be favourably placed for evening
observation in Taurus for the next several months. Don't
miss it! Saturn holds bounteous detail for even the small­
est scopes. You can see:
1) Those fabulous rings. They are tilted nearly
fully open to our line of sight right now. Ring A, the
outermost, is separated from Ring B by a dark thin separa­
tion known as Cassini's Division. A 2.4" on high power can
see it now. Ring C, the Crepe, needs a six-inch for it is
nearly invisible. The ball of the planet shines right
through it so look for its tenuous grey at the end-points
of the ellipse,
2) The planet itself shows faint bands not unlike
Jupiter's. A south-equatorial belt and polar darkening
are especially visible. What else can you see? Look with
averted vision and wait patiently for moments of fine
seeing.
3) Lots of moons. If you have a six-inch or larger
you can see more moons than with Jupiter. Titan at mag 8.4
is easy. Identify it and then try to find the others. Use
the chart opposite to help you. Look up the mag and elon­
gation of the moons in the Handbook. Then check your
observation date. Find the number of hours and days from
the nearest elongation to your observing hour. Count it
off on the orbits opposite and you will come to the position
of the moon for your hour of observation. The left inset
shows how the brightest moons might look on any given night.
They are to the same scale as the chart. The right inset
shows surface detail seen with 4" and larger scopes. The
two faintest moons near the planet are Enceladus and Mimas
as seen through the 16 ". They are a real challenge for any
observer and scope. Information does not appear in the
Handbook for Tethys and Dione. For Tethys, eastern elong.
occurs on Dec 2 at 1 hr and every 1d 21 h thereafter.
Dione's is on Nov 30 at 5 hr and every 2 d 1 8 h thereafter.
Those times are EST.
(Mainly for Conville's benefit, I suppose.
-Ed.)Because of the cost of commercially-made Barlows I
decided to look into making one of my own. Starting out
with little knowledge of the subject or how to go about it,
here are my results.
Firstly, the Barlow lens is simply a negative lens.
More simply, it is a lens with one or two concave surfaces.
By using the laws of refraction, the rays of light passing
through the lens tend to diverge. This effect may be used
in the optical system of a telescope to your advantage.
F IG. 1
In the scope the light is in the form of a cone,
focused by the objective lens or mirror. By positioning
the Barlow inside the focal point (F) of the scope the
focus will be extended to F ', the new focal point created
by the Barlow lens. This will have various effects on the
performance of the telescope. These effects can be deter­
mined by the following equations:
1 ) 1 = 1 + 1
B
A
f
2) x = B/A
1)
tells us how far F ' will be moved. 2) gives the
magnification factor, A is the distance the lens is inside
F. B is the distance of F' from the lens, and f is thefocal length of the Barlow (negative, since the lens is
a negative lens).
By taking a close look at the effects of the position
of the Barlow (it helps to use a computer if you are lazy
like many of us) one can plot the performance of the foci
as you make A approach the numerical value of f. At this
point B becomes infinite and the light is made parallel,
with infinite power x. What is the kink?
The answer, in a word, is resolution. Resolution
determines the amount of detail you can see with your
scope. The resolving power of a telescope is dependent
upon its diameter. This fact is not usually considered
by salesmen of 1 " scopes with an advertised power of 500 x.
At this power Jupiter would be seen as a blob, with no
detail.
However, when used correctly the Barlow lens may be
an important addition to any set of oculars. Generally
very short-focus oculars are required for high power, but
at the cost of very short eye-relief and perhaps a poor
image owing to the difficulties of making tiny lenses
accurately. With a Barlow you can use a longer-focus, more
accurate eyepiece and get the same power.
In building one of your own, the lens should be of
good quality. Any defect in the glass will disperse light,
disfiguring the image and reducing detail. The f of the
lens should be carefully considered. If it is impractical
to have the lens too far inside focus, it should have a
relatively short f. Another interesting thing to note is
that if the f is rather long, both A and B have to be
large for a given x, so you will need a long extension
tube to put your eyepiece in. Also, the farther in A is,
the larger the Barlow lens must be to intercept the whole
cone of light. Barlows usually have f = -40 to -60 mm
and are used at x = 2 to 3 . For a single lens (non-achro-
matic) it is probably best to use longer f and lower x.
Suppose you have your lens and know where to put it.
The next thing is to mount it. Buy, or otherwise obtain,
two tubes of slightly different diameters, one fitting
inside the other. The lens is mounted in the smaller at
one end. The other tube is fastened or glued to the otherend to hold the eyepiece. The lens must not be glued in
place. If it is, any changes in temperature will cause it
to deform and in doing so ruin your image.
By building your own Barlow there are wider ranges
of power open to you. For prime focus photography the
image is very small and you cannot extract much detail.
The Barlow will increase the image scale by the factor x.
Finally there is a sense of satisfaction you get from
building something yourself. Something that is useful.
* * * * * * * * * * * * *
OBSERVER OF THE YEAR?
WHO. ME?
If you want that coveted pin with "Observer of 1971"
engraved on it, you'd better get busy considering both the
quality and quantity of your observing during the year, or
frantically start observing right now and keep it up to the
very last deadline. That hasn't been set, actually, through
an oversight, but will have to be the January meeting of
the Observers Group.
To be considered, you will have to submit a written
account of what you have done to the Awards Committee.
So get busy, huh?
Confucius Say; He that hideth his light behind a
bushel is a bit dim.METEOR REPORT
Ken Hewitt-White
To date (Nov 19) the group has observed 75 nights
this year. We are budging 6000 meteors recorded which is
less than last year's total for 60 nights but is quite a
reasonable figure nevertheless when we consider the cir­
cumstances, The circumstances are that North Mountain
has now more pull than Q.S. so that meteor work is largely
reduced to solo efforts in a cot beside the 16 ". When the
team as a whole does get together on weekends or major
shower nights, Murphy's clouds prevail leaving us empty-
handed. The most recent shower maximums to befall this fate
have been the Orionids, Taurids, and Leonids. Add to this
the Quadrantid, Lyrid, and Perseid maxes and you can readi­
ly see why our 75 nights have not yielded more meteors.
We will try for .333 success on Dec 12/13 when we go
for the Geminids. But your co-ordinator notes that 7
meteor observers have an astronomy exam on the 13 th!
Could there ever be any greater irony? One will have to go.
Sorry, Prof ...
My sincere appreciation goes out to all those who have
offered their help in meteor reductions since ray appeal in
the Oct Astronotes went out. No less than five people have
offered and given help in this endless task. In particular,
Chris Martin has set up camp in my basement for days on end
in helping to reduce data, Peter MacAulay is writing a
computer programme faster than I can supply ideas. Every­
body, thanks!
J . Buchanan and H-W Company, atlas makers, are now
working on ways of making new plotting maps for the group.
To be avoided is the stereographic and orthomorphic pro­
jections which place great distortion in declination on
the maps we now use.
New meteor observers are welcome but please bear with
us. Transportation to Q.S. is becoming increasingly
scarce. If you have your own way out it will help. I will
try to help the others as best I can.
Call me at 733 - 4949 .
* * * * * * * * * * * * *
(Hey, did you catch that nice Editorial in the Ottawa
Journal, November 20 , "The Stars at Night", mentioning us?)THE GRAZE OF NOV 3
John Conville
This article could be done in a very humorous style,
to try and remove some of the sting from the failure of
this particular graze expedition. That was the original
plan, but there is a lot to be learned by this disaster
beyond a few bad jokes. The problems were numerous, the
first being the weather. At the time of the graze it was
perfectly clear - something that it was not supposed to be.
Earlier in the evening I had started to call observers and
say that unless they were phoned back they should forget
about the graze. This was some four hours before the event
and at that point in time the sky at my place was socked in
from horizon to horizon, with a forecast calling for 'clou­
dy tonight'. As a result of the confusion with regard to
the status of the expedition one observer was lost and
general chaos was rampant.
In future a graze which has been fully prepared for
will never be called off. It will be up to the individual
observer to decide that the fact that it is snowing with
gale force winds would make the observation of a graze
impractical. In this respect I wish to thank Bill Dey and
Jack Horwood, who in face of clouds and scattered showers
went out to the graze site, which caused the co-ordinator
and his cohorts to abandon another astronomy lecture and
go out and take a stab at what looked, at that time, like
a dead loss.
The rendezvous time was set for an hour and three
quarters before the graze, at a point not far from the
line. This time would have been adequate if the positions
the teams were to be set up in were known accurately in
advance of the graze. In this respect, on future grazes,
in the afternoon before the event the co-ordinator will
have to go out to the line and put markers, coloured stakes,
and such at the points where he wants the observers. On
this graze all that was done was a drive out to the various
roads which were suitable to find the best one for the
task. I wish to thank Rick Lavery for his chauffeuring
contributions. The actual marking of the observers' posi­
tions was going to be done just prior to the graze, but as
a result of Al Miller's van falling into the ditch that
didn't occur, seeing as I was travelling in the van with
the surveyors chain.The accident with the van also removed the "infor­
mation run" from existence. This was to answer any ques­
tions about the actual observation of the graze. Because
of the absence of this Question Period, many people watch­
ed the wrong star which was brighter than the star we were
trying to observe and on the opposite limb. Because of
the problems of positioning and answering any questions
while actually on the line it has become obvious that the
graze Co-ord needs his own, or access to his own car.
This is something which I am afraid I cannot supply. (So
vote for Tom Tothill for Graze Co-ord.*). The star and
pertinent data questions "could be solved by the publica­
tion of a sheet with a picture of the star with the moon
and some of its prominent features marked on.
The main point of this disaster is that it is imposs­
ible to observe a graze of a 4 .4 mag star on the bright
limb, especially if it is 99 % sunlit, and get results.
This is the main point of contention; future graze co-ord-
inators please take note. (4.0 should be possible on the
dark limb).
I would like to thank Jack Horwood who supplied any
of the 12 teams which had breakdowns with CHU and tape
recorders.
But ...¢
By popular request there will be a repeat performance
of a graze on the night of Dec 28 at 19:31 EST. The
theatre of action will be to the east of the city just to
the east of Kempark and CFB Leitrim. If you didn't plan to
attend the last graze and wish to try this one please
contact me at 733-8299. The star is 3.0 mag and the moon
90% sunlit. This is a dark limb graze.
* * * * * * * * * * * * *
* Nuts! It only cleared up because he chickened out.
#
It's the impertinent questions that give all the
trouble.
¢ Without doubt, we get more hilarity out of these
graze trips than anything else we do. What's one
lousy failure among so many? Vote for Conville.
-Ed.REFLECTORS - PART 4
Allen Miller
Polishing
When you feel your mirror has been satisfactorily fine
ground, polishing can be begun. There are several ways of
doing this but the conventional method of pitch in squares
on a tool is ray choice. The squares should be 1⁄4" thick
and no larger than 1 " for a 1⁄4
4
"
mirror; 2 " for a 12 1⁄2".
Actually 3/4 " squares are good for a
These can be
put on the glass tool in two ways:
1. Pour the pitch on to the tool that is surrounded
by aluminum foil to a depth of 1⁄4" and press a rubber grid
in with the mirror's face using a thick rouge solution as
an anti-stick lubricant.
2. For steep mirrors or large mirrors it is better
to stick individually mould-made squares on to the warmed
tool. Space them all about
1⁄4
"
apart.
In both cases, after the squares have been made let
the mirror (cleaned) and a weight sit on the pitch lap
(cleaned) with washed rouge (see below) as the lubricant
until contact on every facet (square) is made. If this is
neglected your mirror will become badly disfigured and a
return to fine grinding is in store.
Washed Rouge:
Take 2 teaspoons of dried rouge and place in a 10-oz
jar. Add water to 3/4-full level. Seal jar and shake for
1 minute. Put jar down and loosen lid but leave it on.
Let jar stand for 2 minutes. Decant liquid, leaving solid
sewage in jar. Let the decanted liquid settle and pour
off excess water.
Polishing:
From my experience polishing with a 1/4 stroke, pitch
lap on top has been very successful in not giving a turned-
down edge. I recommend it for all first stages.
Remember:
1) Use only the washed rouge to avoid scratches.
2) Place tool on mirror (splattered with rouge) verycarefully and slide it off one side half way and back half
off the other side. Then press with a 5 lb weight for 5
to 10 minutes before beginning polishing,
3) If "hanging" or "sticking", not to mention an
audible scratch is heard, stop polishing. Clean and re­
press lap using warm water if necessary.
4) Never polish with a "hot" mirror.
room temperature is reached.
Wait until
* * * * * * * * * * * * *
Reason has its moons
But Moon not hers
Lying there reflected in the sea
Confounding her astronomers
But oh delighting me.
-D. Parton
sometime on Aug 13/14, '68
while supposed to be
observing meteors,
* * * * * * * * * * * * *
THE SCHLOSSING SAGA ( 7 )
Tom Tothill
"TTime!!!" said Mavis Tinsley, whose optics were good,
a split-T ahead of Hatha Ball.
"Boy! What a fireball!!" said Ravery, locking on the
Super Sixteen. "Think we can follow him all the way to
cutoff?"
"Not a chance. Seeing's too bad," said the Turkish
Ambassador, and headed for the harem in a cloud of dust.
There was no denying that Dill Bey's practicality had
brought him a long way from his humble native village.
"I sure hope Red has his boss's permission to travel,"
said Jake Corewood, "Otherwise there'll be hell to pay if
he gets back."
"Who's his boss?"
"That dog of his. Bandy. Been programming him for
years, but the poor devil doesn't know it."ASTRO NOTES
TO