AstroNotes April 1969

EDITORIAL . MARS PROFILES . OBSERV1NG GRAZING OCCULTATIONS . A LETTER FROM John Howell

Pages: 

8

Download PDF version: 

ASTRONOTES  Vol. 8, No. 4 April, 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 Ottawa Centre Council met on March 12 to discuss
a number of subjects of special interest to the Observers
Group. Foremost among them was the request for $200 to
enable a start to be made on the 16-inch telescope. Council
came up trumps as usual, upping the figure to $225 to permit
the mirror blank to be ordered without the delay that might
be involved in seeking immediately the voluntary contributions
that we all know will be needed as well. The ownership
of the telescope will vest in the Centre as a whole,
but its use will be under the control of the Coordinators
of the Observers Group.

With regard to the Constitution, it seems that the
Society was formally transferred into the Royal Astronomical
Society of Canada 1968 on February 1st, the ballot
which we deem illegal under the old Constitution having
produced a concensus in favour. One point in the covering
letter to the ballot which we should have mentioned was
that members may obtain a copy of the new Constitution in
full by writing to 252 College St, Toronto 2-B. We urge
all members to do so, and to request also a copy of the old
Constitution which has not appeared since 1957 - long before
most joined the Society.

The question of the proposed National News Letter has
been taken a step further in the sending of a letter and
questionnaire to Editors of local news letters, to secretaries
of Centres, and to National Secretary for information.
Ottawa Council has materially assisted this endeavour by
adopting a resolution asking National Council to provide
facilities for a meeting of Editors, delegates of Centres,
and interested members at the General Assembly, and space
in the Agenda for a report on their recommendations.
There is a move afoot at National Headquarters to seek
a raise in membership fees, probably to $5.00 for students
and $10.00 for adults, in view of the fact that the Society
is losing money. We have been unable to find any Annual
Report for 1968 to assess the urgency of this move.

MARS PROFILES

Bill Dey

These are outlines reproduced from Sky & Telescope
for March in an excellent article by C.F. and V.W. Capen
of Table Mountain Observatory, California, on the coming
opposition of Mars.

You may find them useful for drawing Mars around the
dates shown. E and IV may be obtained by letting the image
trail in the telescope field.

Main features such as the polar caps, Syrtis Major,
etc should be drawn first and the finer details added
later. The longitude of the central meridian of Mars is
available on page 61 of the R.A.S.C. Handbook.

The apparent size, phase, and axial
orientation o f Mars’ disk. Its angular
diameter is, left to right, 5".4,
11".2, and 19".3. The rotational axis
is indicated by the upper (south) and
lower tick marks.

Aspects of Mars during the second half
of 1969. Its size will be (left to right)
18".2, 9".5, and 5".9. The nearly horizontal
ticks in five of the six views indicate
the direction in which the defect
of illumination is greatest.

OBSERV1NG GRAZING OCCULTATIONS

Hal Brock (Akron, Ohio)

Several recent issues of Astronotes have contained
articles on endeavors to observe grazing occultations.
These articles have been read with great interest (and
more sympathy) by this writer. Imagine observing an event
at 10 degrees below zero. Brrr...! The thought makes one
shiver. In the Akron area we have difficulty getting
observers out if the thermometer drops to the freezing
point of water, though several are willing to observe from
their home sites at much lower temperatures. Ah! such is
human nature.

Our local amateurs have planned expeditions for grazes
about three times a year for several years. All but three
of these have gone for nought because of weather: clouds,
rain, etc. On one of the successful endeavors, two observers
saw the graze between clouds but, because other teams saw
only clouds, their report was discounted. On another
expedition one observer saw the graze but was unable to
obtain a useful timing. Our best effort was the mid-afternoon
graze of Antares in October 1967. Unfortunately, we
were too far from the graze line and saw only an ordinary
occultation.

A long planned vacation trip to Texas coincided with
the Jupiter occultation (not planned) last October. The
writer was privileged to be included in the grazing expedition
headed by David Dunham of Yale and coordinated by
John Cotton of Dallas. A briefing session at the planetarium
of San Antonio College scheduled for 8:00 p.m. got
underway at midnight, after which we left for a fast 110-
mile drive to the observing sites. A 4¼" cassegrain
telescope, placed at our disposal by a very kind Fort
Worth amateur Mr. LaVerne Biser, was set up on the highway
berm and we dozed in the car for the hour or so that
remained before moon-rise.

By 6:15 a.m. the moon (a crescent 2½ days before new)
was about 20 degrees above the eastern horizon and Jupiter
glistened like a jewel, pendant just below the southern
cusp. The beauty of this view in the comparatively soft
(temperature about 50 degrees) southern sky is beyond my
ability to describe in words. Ours was perhaps the optimum
site for the event since we saw two disappearances and two
reappearances of the planet following the first contact
about 6:35 a.m. Both events occurred within 10 or 12
minutes, the exact times were turned over to the coordinator
and are not available at this writing.

An arc of light over the occulted planet was observed
by this writer. Under the caption "Unexplained Occultation
Phenomenon" this observation is mentioned in Sky & Telescope
(Feb '69, p. 122). The planet passed behind two lunar
mountains, the first lower and narrower than the second.
Just as the planet was completely covered by the first peak
I became aware of an arc of light over the planet's position
and just above the moon's dark limb. It reminded me of
the glow of a distant city. The light was brightest near
Jupiter's assumed position, becoming fainter away from the
limb. As the occultation deepened* the arc diminished.
But it remained sufficiently bright so that I could follow
the planet's progress behind the moon's limb. Just before
Jupiter reappeared from behind the first peak, the glow
became more visible, but it vanished the moment Jupiter's
disk began to emerge. The effect was repeated behind the
second peak.

Though still unexplained, one guess is that the edge
of Jupiter's bright disk was so nearly tangent to the lunar
limb that light reflected from the upper Jovian atmosphere
was visible to an observer at just one site. Neither of
the adjoining teams saw the glow.
This one observing experience more than repaid all
the previous abortive efforts. If you don't look* you
won't see.
* * * * * * * * * *

Confucius Say: Wish I'd thought of that one.

* * * * * * * * * *

We are delighted to have this contribution from
Mr. Brock* who has been an Ottawa member for several
years. Needless to say* Murphy's Law beat us again for
the graze of ZC 425 on March 21. The coming cold front
was too late by about 12 hours. -Ed.
HOWEVER .... Tom Tothill

... It was here in time for the Pleiades occultations
and in fact gave us perfect conditions. As a result, your
lunar coordinator happily reports that he is working on
his second ounce of data (only the solar group deal in
pounds!) to transmit to those who keep track of the moon.
A preliminary - day after - survey indicates a total of
132 timings for the evening. Nice work, everybody!

A LETTER FROM John Howell

(President of the Calgary Centre)

I find I am a little envious of the all-round excellence
of your Centre's observing activities - what is your
membership? 150 or more? We have a 75 to 90 level in
Calgary. To my knowledge there were 34 'scopes in the City
in 1965, and since the Planetarium has existed about 80
mirrors have been tackled. But active members who record
details - one other besides myself!!

There are about a dozen who are willing to come out
for grazes etc, but these good folk just browse around the
skies occasionally. In fact I believe the only time some
get their scopes out is at my bidding! One of our young
members Dave Cluett is trying to organise a "Messier Club"
and is doing a good job with his maps for The Observer.
Sorry to hear of your continuing feud (like us) with
Murphy's Law! We haven't got any good grazes for the next
2 months to my knowledge, but my extended list gives a
couple of 8+ mag. ones for my dome, besides a couple of
9th for the March 23 Pleiades passage.

We are conducting the A.T.M. class at the Planetarium
and have just got it organised with 4 of us as "instructors"
(we have a lot to learn too!) but the City Fathers slashed
the budget and the paid instructor at the Planetarium was
one casualty.

There was talk of dismantling the A.T.M. rooms - there
are 3 rooms for rough, fine, and polishing stages. We have
saved them for this year at least and hope to keep them as
our "private area" with luck. We have set up a display in
the centre room - 5 'scopes that I know aren't being used.
Room 1 is for all grinding now, with 5 pedestals. As
we don't expect much more than 5 or so in session at once
the display is in Room 2. There is a 40-year-old 8-inch
f/12 Cassegrain, a really lovely fork-mount 6-inch f/8
Newtonian utilising a small aircraft (crashed!) wheel fork
very light and stiff, another 6-inch (f/13 !!, but what a
lovely view it gives of Saturn), a nice 6-inch Springfield
mount, and finally our Centre's trusty 60 mm Unitron.
The display draws many comments from visitors - "didn't
know there was so many telescopes in Calgary" etc. Sam
Litchinsky our Editor is getting cracking with his camera
to get as many pictures as possible of different instruments
that do exist in the City. We have three 10-ft domes,
two being used, which surprises people also.

A recent letter from the USNO requested us profile
plotters not to do profiles for stars fainter than 7th mag
but to spend our time on "look-ups" for reduction of
occultation observations - there is a terrific backlog—
I have done 300 since Christmas and have just received my
4th batch of 100. There are three elevations to check for
each occultation - quite meticulous and demanding work - I
find about an hour of it steady is enough, about 15 or 20
observations in that time so I'm not idle long! I have
made 14 "timings" for 1969 - going great guns so far. I
was a little disappointed with my 1968 output, 38 altogether
plus all sorts of poor ones - you know, just missed it for
some simple thing - generally 'scope adjustment at the
critical moment! I made one of my better efforts a couple
of nights ago, a 7.1 mag disappearance with the moon 99%
sunlit. Seeing was excellent; I stopped my 10-inch down
to 6 inches, used 200x and followed it in to the dark
sliver of an edge and "bingo" - 38.6 seconds! Prediction
was 38 sec - how about that! I'm using the one second
delay system now. I find it is good for these difficult
ones as you can be positive of the event before starting
the watch and it virtually obviates the "personal equation"
If I'm at all dubious I give my P.E. of course, 0.2 sec or
0.3 if I'm slow. I'm trying the "eye and ear" method but
WWV is a variable quantity and I can"t rely on it so always
use the watch. For that 7.1 mentioned above I got 38.5
mentally against the time signal; I was counting the beats,
so I figure ray P.E. was close to 0.1 sec as they ask us to
strive for.

Please mail me the data pronto for that graze you
mentioned (ZC 425) - PA, AA, Libration Long & Lat. I can
give you a profile from that within 24 hours of receipt.
(He did, too.-Ed.)

As your Astronotes put it "You can almost smell the
successful graze that will soon be achieved". So if I can
help "smell it out" I will.

I'm looking forward to meeting you at the Toronto
General Assembly in May. More about that later, but I shall
be thar! Good grazing!

* * * * * * * * * *

(Yes, folks, there is a real Observer for you, a Friendly
Fireball who conducts correspondence like this with 30 or
40 people around the globe, always helpful, enthusiastic,
and cheerful. It wasn't meant for publication, but we find
it vivid and inspiring enough to deserve it. -Ed.)