AstroNotes 1980 June Vol: 19 issue 06



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ISSN 0048-8682
The Newsletter Magazine of the Ottawa Centre of the RASC
Vol. 19, No. 6 $2.00 a year June, 1980
Editor........Rolf Meier.......77 Meadowlands Dr.W ...224-1200
Addresses Jacqui Tapping...61 Oval Dr., Aylmer...684-1186
Circulation...B arry Matthews...2237 Iris St..........225-6600
The availability of refreshments at lectures and
Observer’s Group meetings promotes the social contacts
and informal discussions that stimulate interest and
participation in the activities of the Centre. We are
enjoying this service through the kindness and dedication
of TED Bean , who now wishes to retire. Anyone interested
in carrying of this important and worthwhile task, please
contact him at 224-7318.
On Friday the 13th of this month the Conference on
Astronomical Photoelectric Photometry will be held in
Dayton, Ohio. The conference will be about photometry of
variable stars and high speed photometry of occultations.
This is to be an informal conference for anyone interested
in the subject. It is being organized by Russ Genet of
nearby Fairborn, Ohio. Anyone wanting more information
should get in touch with me. Although I will not be able
to attend, this conference is a good idea and I will be
receiving a copy of the proceedings. I will let you know
the results of the conference.In the February issue of Astronotes I reported on the
expedition of 16 members to Algonquin Park on December 30,
1979, to observe the grazing occultation of Aldebaran.
The result was that 8 of the 9 stations observed a miss
under clear skies. Only the most southern station recorded an event which was a 2.6-second disappearance. The
conclusion at the time was that the actual graze line
was south of the prediction.
In the April issue of Occultation Newsletter,
published by the International Occultation Timing
Association (IOTA), reports from other expeditions confirm
that there was a southern shift of the graze line. In
Lockport, Illinois, half of the observers had a miss,
including 3 of the 4 IOTA officers stationed there. Near
Wiarton, Ontario, 18 stations were set up over a distance
of 1.5 miles; 13 of the 18 stations recorded a miss in a
cloudless sky.
Analysis of the Lockport observations indicated
that the shift amounted to about 0 . 5” south, or approximately 1 km. In our case, to only station to observe an
event was 1200 m south of the predicted graze line. At
Wiarton, the graze expedition leader, Douglas Cunningham,
was one of the lucky ones. He observed 13 events, including blinks, flashes, ons, offs, and dimmings; a
spectacular graze indeed!
It appears that there is an error in the method of
predicting Aldebaran grazes because similar grazes of
Aldebaran and other Hyades stars have shown a similar
shift to the south. Therefore the predicted graze line
for future north-limb grazes of Aldebaran will be
shifted 1 km south. A report of our observations has
been sent to HMNAO in England as well as to David Dunham
in the United States.
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Reflector Telescope, 4-inch to 6-inch mirror, with
mount and eyepieces. George Wright, 821-1820.
# # # # # # # #Mary Geekie and Renee Meyer
Chairman Robert Dick opened the May meeting at 8:27
pm. 59 people, 15 of whom were non-members, attended the
meeting. Rob reminded the group of the upcoming Stellafane
convention, to be held on August 9. For those interested
observers, the registration fee is $5. Also, Rob informed
the group that the "Beginner's Package" is going to be reissued. For more information concerning this package for
beginning amateur astronomers, contact Brian Burke.
Robin Molson then proceeded with the IRO update. The
mirrors have been cleaned, the scope has been aligned, a
new pulley installed, the screen door and drive have been
removed for repair, and rubber straps have been installed to
protect the telescope.
Instrumentation coordinator Ted Bean reported poor
attendance at the last telescope making workshop. Of the
18 telescope kit buyers, only 6 were at the workshop. Ted
is wondering where the telescopes are. Ted added that
the experienced telescope makers and observers are more
than happy to provide information and assistance. On the
subject of mirrors, anyone knowing the whereabouts of our
8-inch mirror is urged to contact us. Thank-you!
Planetary and occult coordinator Brian Burke proceeded
with the planet review. Mars is 0.8° north of Jupiter,
and Venus will reach greatest elongation this month. Brian
also noted that, when using the Handbook for occultations,
it is important to read the footnotes. The CHEZ-FM
astrologers waited all night to see an occultation which
was only visible in the Antarctic! By May 5, Venus will
be 30% lit and will approach the crescent phase by early
June. Brian sends a not to all those observers who participated in the Aldebaran graze expedition - IOTA reported
that the graze line was shifted 1 km to the south. There
is a report on our expedition in the April issue of
Astronotes. Brian is still looking for a clearing-house
for data and predictions for grazing occultations.
Dave Fedosiewich followed with a detailed description
of how to find Pluto at magnitude 14. He informed the
group about charts in the January issue of Sky and Telescope dealing with Pluto's position. He also commented
the the Handbook's data is inaccurate. Dave then displayed many celestial slides of constellations, planets,
and heavenly bodies.
General Assembly Display (GAD) coordinator RobM cCallum proceeded. He urged all those active observers
to dubmit displays for the Halifax G.A. in order to maintain Ottawa's illustrious display reputation. Also, Rob
proposed that a meteor observing session might be held at
Quiet Site by the end of May or the beginning of June.
The coffins at Quiet Site are unusable, and it has been
suggested that new coffins be built at IRO.
Next, John Molson related to the group how he built
a 4¼-inch Gregorian telescope in 2 months. The objective
is f/3 and the diagonal for the Newtonian focus can be
removed in order for the telescope to act as a Gregorian.
John displayed several slides showing how a Foucault
tester functions and drew several complex diagrams depicting ellipses and eccentricity. John has observed
sunspots using his well-constructed telescope and reports
that they look very good.
Jim Zillinsky informed the group that a workshop will
be held soon for those observers interested in overhauling
the IRO radio telescope.
Rolf Meier followed with solar photography and handouts for everyone and explained this month's and last
months astrophotography topics: mounted and solar photography. When photographing the sun, it is always necessary
to reduce the light intensity. The simplest method is
projection. Other methods include Solar Screen ( 2 layers
of aluminized plastic) for which you must experiment for
exposure times, and eyepiece filters, coated with gold,
aluminum, or silver. Welder's glass is good for binoculars, but is not available in large sizes for telescopes.
Rolf then explained the basic princples involved in
equatorial mounts. The drive motor must move slowly and
smoothly, but this is hard to accomplish. Thus, the motor
turns quickly, but is slowed down with gears. Rolf also
explained the function of the oscillator, which is used
to change the frequency of the current in order to control
the speed of the motor. Rolf accompanied his informative
talk with solar slides and photos from Stellafane depicting
various telescope constructions.
Rob Dick displayed photos showing the contrast improvement using a red filter .
Philip Forsyth provided for the group handouts detailing the positions of Jupiter's moons during the past
Rob Dick informed the group of various items of interest - an article in S&T on types of film; max of the
Aquarid meteor shower; no star nights in May; IRO Committee
looking for plywood for new coffins at IRO. Ended 9 :29 pm.On Thursday, June 19 there will be a rather rare
astronomical event. This event is a lunar occultation of
a major planet. The planet is Saturn and on the 19th it
will disappear behind the moon's dark limb at 13:19.3 EDT
and will reappear a little more than an hour later at
1 4:2 2 .2 EDT from behind the bright lunar limb. Although
this is a daytime occultation, you should have no trouble
seeing Saturn since its magnitude is 1,3. The times
given have been corrected for Ottawa. The method of
timing this type of occultation is the same as any other
except for one important difference. There will be a total
of four times to record. There could be more if the rings
are visible but I doubt if they will since they are so
close to being edge on. With four contacts to observe it
will be best if you use a tape recorder to record your
voice and time signal, then you can go back over the tape
and obtain accurate times using a stopwatch. Please make
every effort to observe this rare event and give your
results to me at the next meeting.
Before giving the details for this month's star
night, I would like to report on the last one we had. On
Friday, April 18, a star night was held at Robin Molson's
home. The star night was well-attended with at least 25
people present. The centre of attention was once agian
the major planets. The rings of Saturn were just visible
as a very thin line. I would like to thank Robin for
allowing us to use his place and a special thanks to
Mrs. M olson for the many munchies she prepared for all
the hungry observers.
This month's star night will be held at the Indian
River Observatory on either the 13th or 14th, whichever
is clear first. I suggest you try to get out to IRO
for 20 :30 so that you can see the telescope while it is
bright enough. With many of the interesting summer
deep sky objects coming into view there will be plenty to
observe. You will also be able to look at M ars, Jupiter,
and Saturn, which will all be high in the southwest at
sunset. I look forward to seeing you there on the 13th
or 14th.COUNCIL MEETING OF APRIL 24, 1980 R. Wlochowicz
Council dealt with the following items of immediate
interest to the membership:
Observatory Committee; Council approved a preliminary set of rules and keyholder obligations with respect
to the operation of IRO.
Astronotes: An editorial board has been formed to
advise the editor and to submit to Council for approval
editorial policy for Astronotes. F.P. Lossing
(733-2715), A.W. Woodsworth (741-2511), and Brian Burke
(521-8856) are the three appointed members of this
board who will be pleased to receive your suggestions
and comments on Astronotes.
Change of address: Effective immediately, the
Centre’s address will be:
Royal Astronomical Society of Canada, Ottawa Centre
c/o Herzberg Institute of Astrophysics
National Research Council
100 Sussex Drive
Ottawa, Ont.
K1A 0R6
Storage: Members who have Centre property (equipment, components, documents, records, etc.) stored in
their homes are requested to transfer it to the
Centre’s storage area. In addition, we would welcome
material of a hsitorical nature such as photographic
recors of past activities of the Centre, articles,
and anecdotes for the "history" file, and observational
data, and copies of papers presented or published by
members for the "data" file. For access to the storage
area, call Ken Tapping (593-6060) or Romeo Wlochowicz
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Articles for the July issue of Astronotes are due
by June 20.
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