AstroNotes 1985 October Vol: 24 issue 09

Pages: 

16

Download PDF version: 

A S T R O N O T E S
ISSN 0048-8682
The Newsletter Magazine of the Ottawa Centre of the RASC
Vol. 24, No. 9
$5.00 a year
October
1985
Editor........Rolf Meier.... .4-A Arnold Dr...... 820-5784
Addresses.... Art Fraser..... 92 Lillico Dr...... 737-4110
Circulation...Robin Molson....2029 Garfield Ave...225-3082
OBSERVER'S GROUP MEETING - SEPTEMBER 6
Sandy Ferguson
Chairman Doug George called the meeting to order at
8:15 p.m. and commenced with a list of announcements and
activities coming up during the months of September and
October.
These included the annual picnic at Irmi
Underwood's farm on September 13/14, with barbeque and dark
sky observing, the IRO public starnight, the following
weekend, inviting Almonte natives to visit our facilities,
the annual Deep Sky Weekend at IRO on Thanksgiving weekend,
October 10 - 12 and a final starnight for the summer season
on October 18 or 19.
For the meteor squad and any others
interested in becoming part of a shower observation team, a
session would be held at IRO for the Orionids on October
20/21.
Brian Burke, Centre President, followed Doug and
reminded us all that membership fees were due on October 1
for the new year. Also a Centre Meeting was to be held on
Saturday, September 21, when Real Manseau, a member from
Drummondville, would be speaking on his work and interest
in creating modern-day copies of antique brass astronomical
instruments.
Rob McCallum was up next reminding us about the Annual
Dinner Meeting to be held November 22, 1985 and delighting
everyone with the news that Bob Thirsk, backup astronaut to
Marc Garneau, was to be the speaker for the evening!
Moving along to the observational part of the meeting,
Rolf Meier was first up with a variety of slides.
An
unusual aurora was observed on the evening of July 16,
which appeared as a bright spot near the Big Dipper and was
observed through Rolf's 17.5-inch telescope.
Rolf also
mentioned the sighting of Comet Halley through a 24-inch
-1-scope at Stellafane, and presented a slide of his own
showing the field for the Comet taken with the 16-inch at
IRO. An image of the Comet was very hard to see, but Rolf
pointed out the area on the slide where the Comet had been
seen,
Rolf then mentioned two other comets of interest,
Giacobini-Zinner, which was around magnitude 8 .5 and Comet
Machholz, which had evaporated. A report on the planets
followed, with Venus, Mars and Mercury available in the
morning sky and Jupiter and Saturn in the evening,
Rolf then presented a series of slides of planets, the
milky way and a few deep sky objects, comparing Agfa 1000
with 3M 1000,
3M beat Agfa way over the distance in
quality.
Finally, there was a series of shots of Hartness House
and the Turret Scope and museum in Springfield, Vermont,
during his visit to Stellafane.
The next talk was a joint effort between Ken Tapping
and Paul Feldman of NRC, which explained how amateurs could
make worthwhile observations over the coming winter months
of the "Aries Flasher", which is now in Perseus,
By
setting up a team of photographers to follow and record
this enigmatic object on film, it is hoped professional
astronomers would become interested enough to persue the
study of this odd phenomenon. It is estimated at least 100
hours of photography would be needed to find the flasher
and pin it down.
After an animated question period, Ken
requested that anyone interested in becoming involved with
this fascinating project should contact him for further
information,
Graydon Patterson was up next with a demonstration of
astronomy software available for his Macintosh computer.
He described a program written by himself and demonstrated
how star clusters could be presented on the monitor and
star maps written in Pascal, A Comet Halley ephermeris was
also available via print out.
With some recent constellation shots taken in Mexico,
Steve Oliva described his photography of Orion, Saggitarius
and Jupiter,
Doug George presented his slides taken on the 16-inch
at IRO, These included some excellent shots of M 16, the
Veil Nebula and M 31.
Frank Roy, meteor coordinator, gave a run-down on the
highly-successful Perseid meteor observation session of
August 11/12 at IRO,
Between 20:00 and 2:00, a total of
seven observers participated in one the best Perseid
showers in recent years.
Two other members were also
-2-reported to have spent the night near Richmond taking in
the show.
Frank also mentioned the upcoming Draconids,
which would be worth watching, even though the peak is
only an hour in duration.
Following this final talk, Doug declared the meeting
closed and invited everyone to join in the stampede for
coffee and cookies.
1985 ANNUAL DINNER MEETING
Rob McCallum
This year’s Annual Dinner Meeting will be held Friday,
November 22 at Algonquin College’s Woodroffe Campus. Last
year’s dinner at this location was well received by members
so those who didn’t attend will have another chance to
sample some excellent food.
Note that the ticket price
remains at the 1984 level of $17.50.
Members will be pleased to learn that the speaker for
this year’s dinner will be Bob Thirsk, a member of the
Canadian Astronaut Program.
Tickets will be available at the October and November
Observer’s Group Meeting or by mail.
Further information
will be mailed to members in October, or give me a call if
you wish - 225-3167 at home, 728-5841 at work.
Guests of members are welcome!
WHERE DID ALL THE GALAXIES GO?
Doug George
Ever notice that the great Coma-Virgo cloud of
galaxies never seems to hang around very long?
In fact,
you can see them as early as December if you are willing to
get up and freeze in the early hours of the morning. Many
people, however, have to go to work in the morning.
They
prefer hot coffee to cold winds, and are not willing to
stay up or get up at this ridiculous hour.
So, let’s
assume the observer goes out every clear, moonless night,
and stays until midnight.
Unfortunately, at our latitude
of 45° north, he is only going to see the Coma-Virgo
galaxies for about three months.
The accompanying diagram shows why.
It shows what
ranges of Right Ascension are visible at various times of
the year.
Line (1) shows the R.A. of objects near the
eastern horizon at the start of astronomical twilight in
the morning. An object at the Celestial Equator with this
R.A. will apper about 30° above the horizon (high enough
for reasonably good seeing). Line (2) shows the sidereal
time at the start of twilight. The sidereal time is simply
-3-the Right Ascension of the zenith.
Line (3) shows the
sidereal time at midnight.
Lines (4) and (5) are similar
to (2) and (1), respectively, for objects in the west in
the evening sky.
Now, the Coma-Virgo galaxies are located at about 12
hours in R.A.
We draw a dotted line (B) between the point
at which the objects disappear in twilight, and the date
when the observer goes to sleep before they rise.
It
doesn’t look good; the line is about as short as possible.
In fact, the line is only three months long!
Now, if we
look
at
dotted
line
(B) , about the
R.A.
of
the
constellation Lyra, we find it is visible for a whole five
months, or nearly twice as long!
While our poor observer
can spend five months plodding around the familiar objects
in Sagittarius, he has only three months to work his way
through the crowded, confusing Realm of Galaxies. For some
of that time, the objects are only visible for about an
hour.
To make matters worse, Ottawa weather is probably
cloudiest in the Spring.
Since the observer is only
looking in the evening sky, about half of the days are lost
to bright moonlight.
So, he only get six weeks of
cloudless observing time!
No wonder it seems to disappear so fast!
Our
dedicated observer is going to have to lose more sleep in
order to see more of this fascinating area.
Now, on the other hand, look at line (5) over the
period of August to October. The sky visible after sunset
is almost the same for two months, as the most western
visible R.A. only increases by about 1.5 hours in this
time.
So, at the time of writing, the evening sky is
almost at a standstill. As a result, the beautiful summer
sky lingers on a bit.
Fortunately, our observer is not
getting too bored because new things are appearing before
midnight at the normal rate of two hours per month.
The moral of this story?
Don’t waste too much time
staring at M104, you’re about to miss a hundred other
galaxies.
* * *
FOR SALE - 1984 Celestron Super C-8 Plus. Mint Condition.
Includes: heavy-duty Meade tripod, enhanced silver mirror
coatings, 8 x 50 Polaris alignment finderscope, 26mm
Celestron Plossl, 7mm Celestron orthoscopic, carrying case
and piggyback camera mount.
Asking $2,100.00. Call Roy Fox evenings at 828-4816.
-4 -THE COMET GIACOMBINI-ZINNER PUZZLE
Sandy Ferguson
On
the morning
of
September
10/11,
after
two
previously unsuccessful attempts, I managed to view the
above comet from the school yard of D. Aubrey Moodie in
Bells Corners. This particular site is rather good by city
standards, and I thought any attempt at finding the comet
with binoculars in the city would be successful. At 04:45,
after about 15 minutes of hunting, I located it as a faint
fuzzy spot, not far from M-35.
The Comet would have been
more noticeable, had the waning crescent moon not been
around, but it was still quite easy to spot once found. I
made a note of its position and estimated the magnitude at
8.5.
I then proceeded to observe variables for a short
time and was delighted to get RZ Cas going in to or coming
out of eclipse.
Two and a half hours later, while driving to work, I
heard that the satellite's fly-through of the comet's tail
had been successful. Great stuff, I thought.
The following weekend, while at IRO I noticed a log
book entry made by Doug George on the morning of September
11/12 - he had picked up Comet Giacobini-Zinner as a
disappointing blob at approximately mag. 10.5!
What
happened?
-7-When
I arrived back home
I double-checked my
observations against my star charts, and there was nothing
in that position that could be confused with a fuzzy 9th
magnitude object. I was, and still am, slightly baffled.
On discussing Doug's and my observations with other
members, we wondered if it was possible the satellite
fly-through had affected the Comet in some way.
It
certainly is a mystery how such an abrupt change in
brightness could occur in such a short time.
If anyone has any ideas as to what might have
happened,please let us know - we're losing sleep over this
one.
* * *
JUPITER OBSERVING
Sandy Ferguson
Has anyone been keeping an eye on Jupiter lately?
Well, I have and it is absolutely magnificent these days.
During the month of August 1 had noticed off and on
just how colorful it was since opposition.
Then on the
evening of September 12/13, while whiling away some time at
IRO, I though an attempt at sketching the planet might be
in order.
For approximately 1 hour, between 20:30 and
21:30, I sat at the eyepiece (12 mm Koenig) of the 16-inch
and between periods of alternately steady and unsteady
seeing, managed to create the drawing you see page 9 . At
times the planet appeared to be brilliant with shades of
orange and rust, with pale yellow and cream colours around
the north and south limbs. The dark areas in the centre of
the planet ranged from rusty orange to pale orange, with a
very deep rust coloured streak on the lower belt in the
southeast.
All through the belts were tiny thread-like
lines and streamers in variations of orange and light rust,
and in one area a small grey patch with pink threads was
evident. Whether or not this was the Great Red Spot, I'm
not sure.
This was the first time I had ever attempted to sketch
the surface of a planet in any detail.
It is a thoroughly
pleasant passtime and I would encourage anyone with access
to a telescope to give it a try.
* * *
-8-UPCOMING EVENTS
Doug George
October 11/12/12 - Annual Deep Sky Weekend!
An entire
long weekend of dark skies to celebrate the opening of the
original North Mountain Observatory (now IRO).
October 18 (or 19 if cloudy)
- Public Star Night at
Vincent Massey Park.
Members are invited to bring out
their telescopes for public viewing. Observations begin at
7:30.
Next month
- Halley's Comet night, date to be announced.
Maps for locating the IRO and Vincent Massey Park are on
the next two pages.
* * *
For Sale
C-11, less than 1 year old,
$4500, Stefan Szrajer, 820-8968.
* * *
9-
cost
$5100,
sell
for-
10 —TWO METEOR SHOWERS WORTH WATCHING
Rob McCallum
October marks the return of two meteor showers
deserving of special attention this year, as the comets
which produce these showeres are approaching perihelion.
The Giacobinids, or Draconids, associated with Comet
Gicaobini-Zinner, produced very strong showers in 1933 and
1946 (observed rates of 3000 to 5000 per hour). The comet
has a period of 6.5 years, so every second return finds the
comet and the earth at roughly the same relative positions,
which happens to result in the earth passing through the
comet's orbit shortly after the passage of the comet.
However, little or no activity was observed during the 1959
and 1972 returns, possibly due to gravitational effects on
the stream by the planet Jupiter.
There hasn't been much publicity about this shower
this year, compared to 1972 at least.
Most professionals
now believe the earth no longer passes close enough to the
stream for any noteable activity to occur, but one
favourable factor is that the earth passes through the
comet's orbit only 26 days after the comet, compared to 58
days for the 1972 non-shower. This is the closest approach
since the 1946 one of 15 days.
A small difference is
theoretically more favourable since the particles the earth
would encounter would have been ejected from the comet more
recently, meaning less time for planetary perturbations to
have a significant effect.
For anyone interested in a more detailed discussion of
this shower, there is an interesting article by McIntosh in
the January 1972 issue of the RASC Journal.
Some relevant details for observers: most people are
using Yeoman's predictions for time of maximum, which is
October 8 at 13 hours UT (that's 8 am EST, a Tuesday
morning).
The moon is not great, as it rises before
midnight and is about last quarter.
I should note that I
also came across a predicted maximum of October 10 at 3
hours UT, by Ottewell.
So take your pick.
The radiant
position is 17h 28m, +54°.
The other shower is the Orionids, associated with an
obscure comet named after Halley.
This is an "annual"
shower, producing hourly rates of 20 to 40 most years.
Several organizations have suggested monitoring the shower
over the next few years as there is a chance rates may
increase with the comet's return.
I personally don't
expect any exceptional activity this year as we'll be
intersecting the comet's orbit ahead of the comet, where
- 12-there shouldn't be any more material. Confirmation of this
comes from May's Eta Aquarids, another Halley shower, which
produced no exceptional activity this year (although an
interfering full moon made it difficult to judge true
activity).
Still, the Orionids are well worth watching this year
as conditions are ideal. The maximum occurs at 6 hours EST
on October 21 (a Monday morning) with a first-quarter moon
setting well before midnight.
One Orionid feature that
many sources don't mention is a plateau effect - rates stay
high up to 5 days after the 21st - so don't write the
shower off if the maximum is clouded out. The radiant is
at 6h 20m, +15°.
A couple of hints for Orionid observers:
these are
faint meteors, so make sure you travel far enough from the
city to have dark skies.
Also, rates are considerably
higher in the pre-dawn hours - don't pack up too early.
Frank Roy is planning observing sessions for both
these showers; see his article below.
* * *
METEOR SESSIONS PLANNED
Frank Roy
Two meteor sessions are planned for October.
The
D raconids reach maximum (according to Yeoman) on Tuesday,
October 8, at 8 am EST. The moon is not favourable as it
rises before midnight.
This session will be at IRO for
Monday night.
It will be cold, so dress warmly and don't
forget your sleeping bag.
There is another maximum time
predicted for this shower by Ottewell for October 9 at 22
hours EST, so hopefully some keen observers will also
observe this second maximum at IRO.
The annual Orionids reach maximum this year on Monday
morning, October 21, at 06:00 EST. There will be a session
for Sunday night, October 20.
The moon will have set
before midnight, so we will try to observe until twilight.
Anyone wishing to observe these showers, please feel
free to contact me at 820-0874.
* * *
STAN MOTT LIBRARY INDEX AVAILABLE
at Observer's Group
meetings. Cost is $2. Currently there are over 400 books
in the library.
The index is 45 pages long.
It was
produced by Frank Roy.
-13-DEADLINES
The deadline for the Observer-of-the-Year Award is the
November 1 Observer's Group meeting.
Submissions should
include either your observing log or a summary of your
observations and programs for this year.
Submit your data
to Doug George,
Entries for the Variable Star Observer of the Year are
also due at the November Observer's Group meeting.
Submit
your data to Sandy Ferguson.
For those who are pursuing the Messier Race announced
in
the
July
issue
of Astronotes , you
may
submit
observations on a regular basis to Doug George, at each
month's Observer's Group meeting.
Observations should
include observing conditions, the instruments) used, and a
brief description of the object as it was seen.
Persons
submitting observations will receive a certificate next
September.
Articles for the November issue of Astronotes are due
by October 21.
* * *
THE REAL 50TH STELLAFANE
Rolf Meier
The real 50th Stellafane was attended by about 20
enthusiastic Ottawa members this year.
The fun started on Friday night, August 16, with
informal talks under the tent.
Since these are quite
variable in quality, many folks departed long before they
ended late at night.
Telescopically, there were few highlights at this
year's annual telescope maker's convention.
Despite the
crouds of 2000+ on Saturday, there was only an average
number of telescopes entered this year. The quality of the
average entry was not as good as in the past.
Only a few
really stood out, and these won the prizes.
Max Stuart
unfortunately did not win with his 13-inch lightweight
Dobsonian.
The judges are slow to accept this particular
design.
The observational highlight this year was Halley's
Comet. John Bortle was able to locate it, with difficulty,
using a 24-inch, on the morning of the 17th.
This is
probably the first sighting of Halley after it went behind
the sun.
Any previous reports of sightings with smaller
instruments are probably suspect.
-14-ASTRO NOTES
c/o Herzberg Institute of A s t r o p h y s i c s
National Research Council of Canada
100 Sussex Drive
Ottawa Canada
K 1A 0R6
MS . ROSEMARY
FREEMAN
NAT. SECRATARY RASC
136 DUPONT ST.
TORONTO ONT.
M5B 1V2
6