AstroNotes 1981 May Vol: 20 issue 05

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A S T R O N O T E S
ISSN 0048-8682
The Newsletter Magazine of the Ottawa Centre of the RASC
Vol. 20, N o . 5
$5.00 a year
May, 1981
Editor........ Rolf Meier........ 4-A Arnold Dr.. . .820-5784
Addresses......C.R. Molson.......2020 Garfield....225-3082
Circulation....Barry Matthews....2237 Iris St.... 225-6600
EDITORIAL
This is a long issue of Astronotes.
Sometimes it is
long and sometimes it is short, although it is never less
than 6 pages.
The reason for the variable length of Astronotes is
due in part to my editorial policy.
I have noticed that
some centres' newsletters are consistently 20 pages in
length.
Looking closely, though, one finds that 18 of
these pages are often garbage.
I have seen newsletters
which print membership lists, detailed minutes of all
meetings, large, poor-quality pictures, and articles which
are ramblings on some obscure subject, all with the idea of
filling space.
Astronotes is not like that.
If you scan the pages of this and other issues going
back over the last 20 years, you will find that Astronotes
is very much dominated by articles of an observational
nature. These include well-documented actual observations,
coming events to observe, and articles describing observing
techniques and equipment.
In addition, there are the
important reports of past and coming events of interest to
members, as well as the occasional humourous inclusion.
What sets the quality of Astronotes far above any
other RASC newsletter is the policy of emphasizing the
original nature of the observational work.
Thus you will
not find information which is easily accessible to Ottawa
Centre members by other means, such as the Observer's
Handbook.
Instead, you may find less common sources
quoted, such as the IAU circulars or the BAA Journal.
Ultimately it is the quality and quantity of the con­
tributors'
submissions
which
determines
the
length
of Astronotes.
So you will generally find a lack of
observational reports when the weather has been bad, or in
-1-the winter when people stay indoors.
There is a lack of
theoretical articles in the summer, when people prefer not
to interupt their holidays to develop equations.
But
spring brings out the best in everyone, with the weather
encouraging observation.
Knowing this now, you can help maintain the high
standard of Astronotes by submitting the kind of articles
which you have seen in Astronotes in the past.
Any new
contributors are always welcome.
* * *
The 19th Centre of the RASC joined the Society on
September 12, 1980.
It is the Kitchener-Waterloo Centre.
They even have an observatory, and a steadily-increasing
membership.
* * *
OPTICKS
Box 6245, Sta. J
Ottawa, Ont. K2A 1T3
B.L Matthews
(613) 225-6600
NEW!
6-inch f/5 Reflector, complete, equatorial mount,
clock drive, setting circles, 2 oculars
guaranteed
for 1 year - (515)......... $550
6-inch f/8 Reflector, same as above
(815)......... $550
1.25- inch Kellner eyepieces: 6, 9, 12, 18, 25,
and 40 m m ............................ . $23
1.25- inch Orthoscopic eyepieces: 4, 6, 9, 12.5,
18, and 25 m
m
.
$39
Barlows, books, atlases, magazines, plus many
other items:
send $1 for price list and catalog
-2OBSERVER'S GROUP MEETING - APRIL 3
Susan Argue
Brian Burke opened the meeting at 8:15 pm with a
request that everyone should attempt to be there earlier so
that the meeting might start at 8 pm.
In the room was a
total of 60 interested people, 46 of them members.
Art Fraser was up to announce that new members should
get their handbooks from him at the end of the meeting.
Robin Molson had some information about the GA and
available grants. He also mentioned receiving the Waterloo
Centre newsletter.
He introduced Astronomy Day, which is
to take place on May 9th . New keys for IRO are available.
Ted Bean was up continuing his talk about telescopes.
The topic for this meeting was diagonal secondary mirrors.
Using slides, he went through their purpose and design.
The purpose of a secondary mirror is "to intercept and
deflect the converging cone of light from the primary
mirror through a hole in the side of the telescope tube so
that the image field at the focal plane may be made
externally accessible for visual or photographic usage."
The diagrams and slides were accompanied by descrip­
tions of what each angle and line represented.
Also, it
was mentioned that secondary mirrors come in many shapes.
Frank Roy was up next showing some of his slides taken
with hypersensitized film.
All the pictures were taken
with Ektachrome 200 at IRO.
The first 6 shots were of the Aurora Borealis taken on
March 25/26.
The ranged from 10 seconds to 2 minutes.
There were some good exposures of Jupiter ranging from 2 to
10 seconds.
Saturn showed up well in exposures of 2 to 15
seconds.
There were 3 other slides containing the Whirl­
pool Galaxy, Bootes, Corona Borealis, Corvus, Crater, and
Virgo.
Rob Dick faced the crowd next with some news of the
sun’s activity before the March 25/26 aurora. A graph rep­
resented information received by the radio telescopes
belonging to Ken Tapping at 435 MHz, and Jim Zillinsky at
230 MHz.
They both picked up bursts around the same time.
The solar activiy at the time of the meeting was reported
not to be exciting but that there were some areas of
activity building.
Rob spent some time explaining the procedure from page
54 of the Handbook on how to correct the sun’s north to the
earth for recording purposes.
Louis Krushnisky reported seeing a large, complex
group of spots a few days before the March 25/26 aurora.
Rolf Meier got up next to represent his 8 x 10
prints.
He wrote the prices on the board.
For members,
-3-colour prints are $15, black-and-white are $8.
For non­
members, colour prints are $20, black-and-white are $10.
He showed some slides of available prints that included
Comet West, a lunar eclipse, Orion, the North American
Nebula, and the Horsehead Nebula.
Brian Burke finished off the speakers' list with the
information that he had transportation prices for the GA.
He went deeper into the topic of grazes and occultations by
defining
them and describing the method he uses
to
calculate where he should set up the graze line. There was
also a request that anyone interested in the April 9/10
grazes should sign the paper at the table.
The meeting closed at 9:50 pm.
* * *
DR. GEOFFREY BURBIDGE ON REDSHIFTS
From March 8th to 17th, the 1981 Forum for Ideas was
held at the University of Ottawa.
As part of the partici-^
pation of the Department
of Physics,
a lecture
was
presented on Monday, March 9th, by Dr. Geoffrey Burbidge,
the Director of the Kitt Peak National Observatory, located
near Tucson, Arizona.
His topic was "The Riddle of the
Redshifts".
Dr. Burbidge explained that problems exist in trying
to explain certain redshift phenomena, such as greatly
different redshifts for individual members of groups of
galaxies which appear to be physically connected.
Although
the dilema was not resolved, an interesting discussion
followed the lecture.
The speaker was introduced by Dr. Yatendra Varshni of
the Department of Physics who, interestingly, does not
believe in redshifts.
* * *
Articles
by May 22.
for
the
June
issue
* * *
of Astronotes are
dueMARCH STAR NIGHT AT IRO
Brian Burke
A public star night was held at the Indian River
Observatory on Friday, March 27. For the second month in a
row, the weather was great.
About 10 of the 25 people
present were non-members and for some it was their first
look at the planets and deep sky objects.
Jupiter and
Saturn were well-placed for observation all night.
Al­
though the atmosphere was somewhat turbulent in the early
part of the evening, it settled down enough later to allow
a glimpse of Cassini’s Division.
I would like to thank members for bringing out their
telescopes and providing rides.
I hope to see more of you
at the next star nights.
* * *
TWO STAR NIGHTS THIS MONTH
Brian Burke
To celebrate Astronomy Day 1981 there will be a public
star night on Saturday, May 9th , this time in the city.
The location will again be Billings Park, at the corner of
Billings Avenue and Lynda Lane in the east end of Ottawa.
The star night will begin at 20:30 EDT. You are encouraged
to bring your telescope and if you do I would suggest that
you begin setting up 30 minutes before starting time.
The
public will be invited through the news media and do not
forget to invite your friends.
There will also be a star night at the Indian River
Observatory on Friday, May 29, or Saturday, May 30. We
will meet at the Carlingwood Shopping Centre at 20:30 EDT.
If you need a ride it is very important that you call me
and let me know.
Once I know how many people will be at
Carlingwood looking for a ride I will be able to ask
members with cars if they can give rides.
If nobody needs
a ride then there will not be anyone at Carlingwood with a
car.
I can be reached at 521-8856.
I suggest you get in
touch with me by May 27th . I am looking forward to seeing
you at IRO and if you have a telescope, bring it along.
*
*
*
-5-THE GRAZE OF ZC 930
Brian Burke
It was the afternoon of Thursday, April 9, and it was
overcast.
However, by 5 pm the sky began to clear.
At 8
that evening, 5 members met at Billings Bridge.
We then
headed down Highway 16 and met once again at MacFarlane
Road.
The predicted limit or graze line crossed the
highway about 200 metres north of this point.
It was
agreed that Rob Dick and I would set up about a mile south,
that Bill Donaldson would go 2 miles south, and that Frank
Roy and Ravi Mehta would be stationed 2.75 miles south.
The lunar profile from the predictions showed two large
mountain peaks and these could be easily seen through the
telescope.
There were a few tense moments when Rob and I were
setting up and the smell of skunk became stronger,
but
fortunately it eventually dissipated.
The location we had
chosen was just in front of a house and needless to say we
got a few strange looks when the occupants drove into their
driveway. We spent the rest of the time there deciding who
would explain to the police, but none arrived.
Everyone was set up well in advance of the time of
central graze, which was predicted to be at 21:12 EST or
02:12 UT on April 10.
All times and dates stated will be
in Universal Time.
At our station Rob did the observing
and I took care
of the timing and recording equipment.
Frank did the timing while Ravi observed at their station.
Both Rob and Ravi observed events but Bill lost the star in
the glare of the moon and did not observe any events.
The
observations are given below.
Station 1: long. 75° 42’ 07" W
lat. 45° 18' 55" N
observer:
Rob Dick
timer: Brian Burke
method:
tape recorder and CHU
events: d: 02h 10m 54s
Station 2: long. 75° 42' 06" W
lat. 45° 17' 42" N
observer:
Ravi Mehta
timer: Frank Roy
method:
tape recorder and voice
events: d: 02h 10m 58s
r: 02h l1m 13s
d: 02h 11m 28s
Since all times are quoted in UT, the date is April
10.
At station 1, the CHU time signal was recorded on
tape.
At station 3, the timer would call out the time each
-6--7--8-
Predictedminute, reading from a digital watch that had been set to
CHU earlier.
The positions were measured from the 1:50,000
scale topographic map Ottawa 31 G/5. The elevation at both
stations was 275 feet.
The diagram shows the limb profile according to the
predictions.
However, Rob and Ravi observed events where
there should not have been any. This may indicate that the
central graze time was earlier by about 40 seconds.
This
can be expected, as graze time predictions have a large un­
certainty since they are interpolated for the point nearest
to the observer.
Thus "zero" time corresponds to 02:12
UT.
I have not included the final reappearance on the
chart because both observers lost the star in the glare of
the bright south lunar limb and did not see the star until
it was well clear of the limb. Rob spotted it at 02:16 and
Ravi at 02:17 UT.
The significant aspect of this graze is that Rob did
not see any other events like Ravi observed.
Therefore,
either Rob lost the star, or it was a total occultation
from our station.
However, the reappearance time observed
by Ravi
is too short
a duration for where he was
stationed.
Although more data
would help, I will go out
on a limb and say that from the data we do have the graze
line shifted south by 1.5 miles, or approximately 1 second
of arc.
It will be interesting to learn what other
observers recorded.
I should point out that all times are
uncorrected but have been rounded to the nearest second.
The report will be sent to the IOC in Japan and IOTA in the
US. This will include a correction for reaction time and a
value for the error.
Therefore, after attempts to observe spectacular and
favourable grazes, we have success with a marginal one.
There must be one of Murphy’s laws involved here.
I
strongly recommend that if you would like to participate in
future
graze
expeditions
that
you
observe
total
occultations.
These will provide you with the experience
and such observations are also important.
* * *
European scientists have, for the first time, recently
created a collision between particles of matter and its
opposite, antimatter.
* * *
-9-SOLAR ACTIVITY OF MARCH
Robert Dick
The sun was quite active during the second and third
quarter of March 1981.
In response to reports of a
spectacular aurora, observations of the radio sun by Ken
Tapping and Jim Zillinsky have been plotted and are
presented here.
Both radio telescopes are phase-switched interfero­
meters focussing south.
The sun drifts through their beam
patterns around noon local time, hence only the activity a
few hours before and after noon was recorded.
Ke n ’s radio telescope,
operating at 435 MHz,
is
located in Aylmer, Quebec.
He recorded numerous bursts, 5
of which were off the scale of his chart recorder.
However, Jim, operating at 230 MHz in Ottawa's south end,
noted more limited activity.
During the third quarter of
the month, both telescopes detected an enhanced daily level
with bursts superimposed.
Louis Krushnisky reported a complex sunspot group near
the centre of the solar disc during this time.
On the
Wednesday night (March 25/26) before the public star night
at IRO, a bright aurora with red curtains was observed and
photographed by Frank Roy and others.
The observations obtained by Ken and Jim are plotted
on the graph on the next page (p.ll).
* * *
MASCON 1981
MASCON is the Manitoba Astronomical Convention.
It
will be held this year at Riding Mountain National Park
near Winnipeg, and hosted by the Winnipeg Centre of the
RASC. The dates are August 1, 2, and 3. The 3-day program
includes lectures, viewing at night, and a telescope com­
petition.
There is a fee for camping, admission, and food.
For
more
information
on this
"western
Canada
Stellafane” (Stellafane is, by the way, held on the same
days this year), contact Rolf Meier.
* * *
-1011Robert Dick
SOLAR ACTIVITY OF APRIL
As reported at the April Observer’s Group meeting,
several large sunspot groups were moving onto the solar
disc.
These groups spread out and developed for the next
two weeks, producing the great aurora of April 12, turning
the sky red.
David Lauzon alerted me at
about 9 pm to the aurora
in its early stages.
At that time it was quite noticeable
under city skies, but I detected no colours. The extent of
the display varied until, as I lay in bed and looked out
the window at 11:30, I saw the sky aglow with a red,
featureless light.
Because of the extent of the aurora (it
covered the entire southern sky) the photographers of the
centre will be hard-pressed to capture the event on film.
Observations of the sun on the previous Friday morning
(April 10) showed a number of large groups stretched across
the western half of the sun’s disc.
Radio observations by
Jim Zillinsky at 230 MHz showed a few small bursts
superimposed
on
a
generally
enhanced
background
of
activity.
However, Ken Tapping, observing at 435 MHz,
showed a much more violent history before the aurora (see
the figure).
On the preceeding three days, large bursts
occured, reaching approximately 58, 88, and 60 solar flux
units.
The background level had been slowly decreasing
during those first days of April.
Those who are interested in contributing data to these
reports should get the information to me a few days before
the Astronotes deadline.
The observations obtained by Ken Tapping for the month
of April are plotted on the next page (p. 13).
Editor’s note:
At the time of this writing (April 19),
there has been extensive aurora activity on practically
every clear night in the last two weeks, most recently on
the night of April 18/19.
* * *
Remember to register for the General Assembly of the
RASC if you are planning to attend.
It will be held in
Victoria,
British Columbia,
on June 26-29.
See the
National Newsletter for more information.
* * *
-12-SHUTTLE FLIGHT A SUCCESS
After a two-day delay, the first voyage of the first
space shuttle, the Columbia, began with a launch on the
morning of April 12.
The mission was a complete success,
including a flawless landing in the California desert on
the afternoon of April 14,
There were a few tense moments
as the on-board TV cameras detected some missing ceramic
tiles on the engine covering, but these apparently caused
no problem.
There were reports of attempts to detect more
missing
tiles
from
ground-based
cameras.
Do
the
ultra-high-resolution cameras exist?
There is some doubt,
but it would be in the interest of the defense department
to keep the public (and the enemy) guessing.
* * *
-13-DISC TEMPLATES
Robert Dick
Jim Hayes was the solar coordinator several years
ago.
To improve his observations and to provide an inter­
esting project, Jim calculated and produced a set of
overlays on which he plotted the longitude and latitude
lines for the sun.
He passed the transparencies on to me
in the hope that I would find them useful in my observing
program.
These 6-inch discs help the observer identify more
accurately the position of interesting features on the
sun’s optical surface (photosphere). The original overlays
were made on thick mylar sheets used for drawings.
The
lines and numbers were drawn on the rough side of the sheet
with a fine pen and ink.
In order to distribute these discs to those interested
in using them, they will be reproduced in Astronotes.
It
is hoped that by providing a template, we can accumulate
observations from members that can be compiled into a
record
which
will
be
suitable
for
presentation and
displays.
These discs can be copied onto transparencies to pro­
vide the user with his own overlays.
Their use is not
restricted to solar observation, but can be used for ob­
servations of the moon and Mars.
Jupiter and Saturn re­
quire elliptical discs.
In order to use them, refer to page 54 of the
Observer’s Handbook for the ephemeris table for physical
observations of the sun in 1981 at Oh Universal Time.
In
Ottawa, Oh UT translates into 7 pm EST or 8 pm EDT.
The
entries on this page are used in conjunction with the discs
of this article.
The corrections in the Handbook should be
applied to the visual observations in order to identify the
axis of rotation of the sun and hence to orientation of the
discs.
Your observations at the telescope should include:
-date and time
-telescope type and aperture
-magnification and eyepieces used
-approximate altitude of the sun and seeing conditions
-position of the north and east limbs of the sun
West is aligned to the earth’s east-west axis and is
easily found by letting the sun drift across the field of
view. Moving the telescope north or south on an equatorial
mounting will indicate the north or south limb.
The sun’s axis of rotation is not parallel to that of
the earth and its orientation will vary throughout the
year.
The table on page 54 of the Handbook is used to
-14--16-
-15-determine the sun’s true axis of rotation from the north
limb.
The table gives the values for P, B0 , and L0 for
every 5 days.
In figure 1 of this article, these 3
parameters are defined.
The north and east limb are
oriented
for
a
refracting telescope with a diagonal
mirror.
On Jim’s discs, B0 = Beta and this value allows
you to select the correct disc.
P is the amount the disc
must be rotated in order to align the axis properly.
It is
measured eastward from the north limb.
L0 gives the
longitude of the centre of the disc.
The rotation period
of the sun varies with latitude so care must be used in
identifying recurrent events at higher solar latitudes.
We will start the series with the disc for a value of
Beta = ±4° so that it may be used for part of the month of
May.
* * *
figure 1
-17-Barry Matthews
SOLAR DISC MEASUREMENT
Solar
observers
throughout
the
free
world
have
standardized the whole-disc projection of the sun to a
diameter of 152.4 mm (6 inches). To enable the observer to
estimate the areas of sunspots or other phenomena, the BAA
(British Astronomical Association) has devised a method of
relating the size of such phenomena to the standard 6-inch
disc.
This enables observers to record, evaluate, or
compare any particular observed phenomena.
I have included with this article a reduced copy of
the graticule used for this purpose (figure 1).
Each
circle gives the area of its associated spot in millionths
of a hemisphere (microsphere).
For the keen observer with
the facilities to use larger projected scales, the label
value is to be divided by the square of the scaling
factor.
For example, 305 mm (12 inches) is twice the
value, and therefore all label values are divided by four.
With a graticule prepared on standard white paper, the
drawing is placed above a light table or window, allowing
easy estimation of spot size. A similar graticule has been
prepared from clear plastic and is available from Barry
Matthews at (613) 225-6600 for $2.
As you can see, the actual technique is very simple.
Any given spot is sized up by the graticule
by eye and
recorded.
Take 3 estimates and record the average.
The
main drawback the seasoned observer will be aware of is,
"What happens if the spot is not dead centre on the sun's
disc?"
Remember to allow for foreshortening.
The
graticule has been designed to compensate for forshortening
by use of the secant.
The projected areas are simply
multiplied by the appropriate secant and then logged.
At this time, I would like to briefly mention the
method of logging your data.
Data taken without adequate
records is worthless as it only gives the observer an
instant of recognition.
Therefore, I am proposing an
observation form that will
provide adequate
records for
subsequent recall (figure 2).
For the armchair astronomers who like the mathematics
of the problem, I have included the appropriate formulae.
r = R √ 2a x 10-3
(1)
where r = radius of graticule
R = radius of projected solar image
a = projected area in microhemisphere
-18-r = R sin (p)
(2)
where r = radius of sector associated with angular
distance "p" from the centre of the disc
R = radius of projected solar image
p = angular distance
* * *
Interested in a particular field
astronomy?
Contact the coordinator of
speak to him at a meeting.
* * *
-19-
of observational
that subject, or-20-
SECTOR
REFERENCERECOMMENDATIONS OF THE FINANCE ADVISORY COMMITTEE
It is recommended that Council:
1.
2.
3.
4.
5.
Identify and approve a program of activities.
Develop a general policy for pricing products and
services, including these items:
2.1
Periodicals will be available without charge to
members.
2.2
There will generally be no admission charge for
attendance at amateur meetings.
2.3 Where a price is charged it shall be set so as to
raise funds effectively.
2.4 Members may be offered preferential prices.
Prepare and approve a budget of expenditures and
revenues.
3.1
The budget shall plan for higher revenues than
expenditures.
3.2
Additional revenues will be generated through an
increase in the membership.
3.3 A committee will be created to assist in the task
of securing continuing and new members.
3.4
An updated mailing list for Astronotes shall be
reconstituted annually.
Identify and implement new sources of revenue.
Make immediate plans for the repayment of the out-
standing debt owing to the National office.
This is a summary list of the recommendations advanced
by the committee.
For full details, contact a member of
council.
These
recommendations
have
been
reviewed,
approved, and adopted by Council.
* * *
"What we
Is like
What we
Is like
have learnt
a handful of earth;
have yet to learn
the whole world..."
-The Poetess Avvaiyar, 1st century BC
-from Burnham's Celestial
submitted by Frank Roy.
* * *
-21-
Handbook,
p.
212,
andA SIMPLE AMATEUR RADIO TELESCOPE
Dave Fedosiewich
The advent of World War II brought about strong
advances in communications and radar technology, and was
the main reason for the beginning of a serious interest in
radio astronomy among scientists all over the world.
Pro­
fessional astronomers seized the chance to explore the
universe on radio wavelengths (as opposed to optical wave-
lenghts) and began finding out that everything they could
see was not everything that there was to be seen. This new
age revelation has come to be one of the major branches of
astronomy
and
has
brought
forth many
of
the major
discoveries of these recent years.
Part of the amateur’s reluctance to get involved in
radio astronomy is the lack of equipment on the market and
the lack of understanding of radio theory and electronics.
In this article, I will discuss some of the more basic
aspects of radio astronomy, and will describe the construc­
tion of a simple radio telescope using readily available
items.
Every hot object in the sky - galaxies, stars, etc.,
emits broadband radio energy that has an energy roughly
proportional to its temperature.
This is called thermal
radiation and will rise in intensity through the VHF and
UHF parts of the radio spectrum.
There are also non-thermal radio sources in space.
These
sources are
created
by high-velocity electrons
passing through intense magnetic and gravitational fields
that surround most stars and galaxies.
The intensity of
nonthermal radiation is highest at the low end of the VHF
radio band. Many radio sources in space emit noise that is
both thermal and non-thermal.
In this case, the amateur
can expect to observe the object across the entire radio
spectrum.
The sun is our most powerful radio source.
Although
it generates much high-frequency thermal energy, intense
non-thermal signals from sunspots and solar flares make it
an excellent subject for the novice radio astronomer.
The
planet Jupiter is the next-strongest radio source.
Since
it is rather cold, its thermal radiation is negligible.
Jupiter’s powerful
magnetic
field, however, sweeps
gigantic swarms of electrons through the planet's upper
atmosphere, creating noise that can be easily heard on 21
MHz and up.
The most fruitful working range for amateur
radio astronomers is in the VHF and UHF bands, where
non-thermal and thermal sources have about the same energy
levels.
A
radio
telescope
can
be
little
more
than
a
-22-directional antenna, wideband receiver, and some type of
recording/readout device.
Whenever a radio source in space
enters the antenna’s beam pattern, the receiver tunes,
amplifies, and detects the signal.
The recording display
then displays and records the results.
Although parabolic antennas are used extensively in
professional radio astronomy, they are not the best choice
for amateur radio astronomers.
Considering both practical
and
theoretical
features,
a tuned multi-element
beam
antenna is the best all-around choice for a VHF radio
telescope system.
As far as the receiver is concerned, it must have high
gain,
low noise,
good
frequency stability,
and wide
bandwidth.
Any wideband
radio receiver that has
a
sensitivity of 5 microvolts or better is suitable for
amateur radio astronomy work.
Commercial FM receivers work
rather well in a VHF radio telescope system because most of
them have good sensitivity figures and a wide predetection
bandwidth.
TV receivers are not very good receivers
because, although they have the required bandwidth, they
have quite poor sensitivity.
The data readout, the final stage of the system, can
be as simple as a voltmeter or as complex and expensive as
a chart recorder.
The former is less useful because it
requires
constant
or
frequent monitoring for readout
levels.
The 110-MHz radio telescope described can be assembled
for about $30, assuming you already have an FM receiver and
a voltmeter.
Although most of the time and money involved
in this 110-MHz system goes into building the antenna,
there is nothing really unusual about it. It is a standard
13-element Yagi array cut for a centre frequency of 110
MHz. The elements can be made from heavy aluminum wire and
mounted on a boom made up of 8-foot long sections of
1.5- inch diameter aluminum tubing. Mount the boom assembly
on a standard 2-inch diameter steel mast to raise the
balance point of the boom to about 16 feet above ground
level.
Use a length of RG-58/U coax cable to carry the
antenna signal to the input of a moderately good FM
receiver.
An impedance-matching transformer can be used to
match the 50-ohm impedance of the antenna cable to the
300-ohm impedance of the antenna input circuit on most FM
receivers.
Then connect a voltmeter that has a 1 or
1.5- volt ac range across the receiver's speaker output
terminals. The meter will now register the system's output
noise level.
A switch at the antenna input on the receiver can be
used to replace the antenna with an equivalent value load
-23--24--25-resistor.
This will provide a reference noise level for
the ac voltmeter.
This way, you can tell what minimum
input signal registers as on the voltmeter and will provide
a reference to compare with background noise from the
receiver.
At this point, if possible, use the ac meter’s
zero-adjust control to set the meter pointing to zero.
This simple 110-MHz system is capable of detecting
signals from at least seven different radio sources of
extraterrestrial origin.
These include the sun, Jupiter,
Sagittarius A, Cassiopeia A, Taurus A, and Virgo A.
Good
luck!
* * *
Spring has come to IRO.
Since the population out
there may now wish to increase, we present the following
for your information:
* * *
KEYHOLDERS TO THE INDIAN RIVER OBSERVATORY
Ken Tapping
Brian Burke
Fred Lossing
Stan Mott
Robert Dick
Brian Stokoe
Paul Mortfield
David Vincent
Bob Caswell
Louis Krushnisky
Frank Roy
T.E.D. Bean
Barry Matthews
Rolf Meier
Robin Molson
Pierre Roy
Robert McCallum
61 Oval Drive, Aylmer, Quebec
2201 Riverside Drive, Ottawa
95 Dorothea Drive, Ottawa
2049 Honeywell Avenue, Ottawa
1855 Wembley Avenue, Ottawa
722 Dickens Avenue, Ottawa
30 Eleanor Drive, Nepean
215 Grandview Road, Ottawa
64 Cedar Blvd, Aylmer, Quebec
1028 Harkness Avenue, Ottawa
3800 Richmond Road, Nepean
117 Rossland Avenue, Nepean
2237 Iris Street, Ottawa
4A Arnold Drive, Nepean
2029 Garfield Avenue, Ottawa
17 Anjou, Aylmer, Quebec
1958 Lauder Drive, Ottawa
* * *
-26-
684-1186
521-8856
733-2715
722-0957
722-5809
731-3174
225-1425
829-7584
684-3019
731-8409
820-0874
224- 7318
225- 6600
820-5784
225-3082
684-0312
729-9977GAS HYPERSENSITIZATION IN ASTRO PHOTOGRAPHY
Frank Roy
Recently, the Ottawa Centre’s Observer’s Group was
introduced
to
gas
hypersensitization
of
photographic
emulsions by Fred Lossing.
In normal photography, exposure times are usually
limited to between 0 .001 and 8 seconds.
In deep sky photo­
graphy,
the exposure
time will range between several
minutes and hours.
Normal film is not designed for these
long exposures.
If a film is exposed for more than a
couple of seconds, it will begin to lose speed.
This
effect is called reciprocity failure.
It is most pro­
nounced on very long exposures and some film may lose a
considerable amount of its initial speed if exposed for too
long.
When a light photon hits the photographic emulsion, a
silver halide molecule is activated.
If this silver halide
molecule does not combine with another molecule within a
certain period of time (in the order of 10- 9 second) then
it will lose its energy to a nearby oxygen molecule present
in the emulsion.
When enough silver molecules combine,
they form a silver halide grain, and it is the size of
these grains that determines the resolution of a particular
film.
Gas
hypersensitization
consists
of
soaking
the
emulsion in hydrogen, which is chemically much less active
than oxygen, and also has a much smaller molecule.
It will
eventually seep into the emulsion and displace the oxygen.
At normal room temperature this process may take days, but
it can be accelerated by heating the film. Articles on the
subject indicate that best results are obtained at room
temperature, especially with colour film.
Thanks to Fred Lossing, I have been able to experiment
with this process and have obtained some interesting
results.
So far I have experimented with Fujichrome 400 and
Ektachrome 200, and will soon try Ektachrome 64 and Tri-X.
The Fuji 400 was soaked for 10 days at 25°C, with the gas
being changed 10 times.
Similarly, the Ektachrome 200 was
soaked for 8 days.
My first trials were on the aurora of March 25/26.
These shots were on the hypered Ektachrome 200 with
exposure times of 30, 45, and 120 seconds.
But the real
test is deep-sky objects.
I used M 51 as a test subject.
I took 3 15-minute exposures with normal Fuji 400, hypered
Fuji 400, and hypered Ektachrome 200.
The most spectacular result is with the hypered Fuji
400.
In the slide, the spiral arras have the intense blue
-27-of the hot, young stars, with a mottled appearance, and the
connecting arm is very evident.
The cores of both galaxies
are much redder than the arms of M 51, indicating a
different star population.
The contrast seems better than
normal Fuji 400 and the background stars are brighter (the
dimmest stars are easiest to see in the hypered Fuji 400),
Normal Fuji 400 is comparable to hypered Ektachrome 200
except that hypered Ektachrome 200 seems to be more
sensitive in the blue, but the Fuji 400 seems to have a
darker background.
With hypered film the sky fog limit should be reached
in a much shorter time.
It should reduce guiding errors
because less exposure time is required.
It seems to
produce a very colourful picture.
Hypered Fuji 400 may
well be the best colour astro film to use.
* * *
OCCULTATION OF SAO 142674 BY 129 ANTIGONE
Brian Burke
On Thursday, June 4, the occultation of the star
SAO 142674 by the asteroid (129) Antigone could be visible
in the Ottawa area.
The key information is:
time:
23:00 EDT
duration:
20 seconds
star's magnitude:
6.7
star’s position: RA 18h 47.6m
asteroid’s magnitude:
10.2
Dec -7° 58’
The path for this occultation is, as usual, rather un­
certain.
One prediction puts the path 300 km north of us
and another places the path 360 km south.
Therefore, as
you can see, Ottawa is approximately midway between the two
predictions.
However, in the March issue of Occultation
Newsletter, there is a report of another prediction which
shifts the path so far north that it misses the earth’s
surface by several hundred kilometres!
The star will be in
the southeast at an altitude of 17.5°.
A telescope as
small as 5 cm can be used to observe this event.
It is important that you locate the star a few days
before the event and make yourself familiar with the star
pattern.
The finder chart with this article should make it
easy to locate the 6.7-magnitude star, also known as
S Scuti.
The map showing the occultation path indicated
-28-that the path north of us is the favoured one.
Keep in
mind that dates and times shown on these two diagrams are
in UT.
Both diagrams were supplied by IOTA.
* * *
-
29-A SUPERNOVA PROJECT FOR THE SIXTEEN
Frank Roy
Several years ago, Rolf Meier suggested in Astronotes
looking for comets with the sixteen-inch (then at North
Mountain). With the giant Erfle, the 1.25° field gives the
capability of detecting faint nebulous objects.
After only
50 hours of search, Rolf discovered his first comet in
1978.
Comet Meier 1978f was at l0thmagnitude in Lynx when
discovered.
To date, Rolf has discovered 3 comets at IRO.
The last one took a mere 26 hours of searching.
Rolf has also started a supernova project in which an
actual print is compared visually to the galaxy.
If any
new star is seen it most likely will be a supernova.
The most likely candidates for supernovae are Sc
spiral galaxies.
On the average, extragalactic supernovae
reach a peak brightness of about 15th magnitude, although
some do become considerably brighter.
Some estimates show
that 3 supernovae will occur for every 100 years in a
typical spiral.
Rolf has demonstrated that it takes about 10 minutes
on normal Tri-X film to get a good picture.
The stellar
limiting magnitude is about 18, while an experienced visual
observer may see magnitude 17 on a very good night using
the 16-inch.
It is possible that a dedicated observer
could detect a supernova in about 2 years if the observer
compares about 30 to 50 prints a month.
I too have begun taking exposures of galaxies and
hopefully will have enough to start my search within the
next two months.
I believe the Ottawa Centre has the capability of
becoming
the
world
leader
in
amateur
supernova
discoveries.
It will be interesting to see who will start
the trend.
Reference:
Burnham's Celestial Handbook.
* * *
Don’t forget about the Eta Aquarid meteor shower on
the evening of May 4. With the moon being new, it promises
to be a good display.
Contact Frank Roy for more
information on this and other coming showers.
* * *
-30-ASTRO NOTES
TCI
MS. ROSEMARY FREEMAN
CAST
NATIONAL SECRETARY
THE ROYAL ASTRON. SOC. OF CAN.
124 MERTON STREET
TORONTO, ONTARIO
M4 S 2Z2