Event Horizon
Can you spot the Supernova
2002B in the first photo? Our
own chair Doug Welch helped to
locate this one. ed.
C. Stubbs, University of
Washington, reports, on behalf of
the SuperMacho microlensing
survey team (including also A.
Rest, R. Covarrubias, A. Becker,
C. Smith, K. Olsen, N. Suntzeff,
R. Hiriart, D. Welch, D.
Lepischak, A. Clocchiati, B.
Schmidt, and K. Cook), the
detection with the Cerro Tololo 4
m telescope (+ MOSAIC II
imager) on Jan. 7.20 UT of an
apparent supernova (R about
20.5) in a galaxy behind the
Large Magellanic Cloud.
The new object was not apparent
in images taken on 2001 Nov. 22
(limiting mag R about 23) and,
based on the accumulated light
curve with data points from
multiple nights, appears to reach
a peak magnitude of R about 20.5
on 2002 Jan. 9.2. SN 2002B is
located at R.A. = 5h40m46s.06,
Decl. = 71o51'15".1 (equinox
2000.0), which is about 2".2 west
of the host galaxy's nucleus.
(C) Copyright 2002 CBAT
2002 January 14 (7791) Daniel
W. E. Green
not 2B
2B
SUPERNOVA 2002B IN ANONYMOUS GALAXY
Hamilton Amateur Astronomers
February 2002 Volume 9 Issue 4
inside ... Chair's report .....pg 2 Fun in the Sun .........pg 7
Ask the Experts ....pg 3 Do Black Holes Exist?...pg 8
Holidays ...........pg 5 In Sight ...............pg 10
Space News 2002 ..pg 6 Calendar ...............pg 11

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Event Horizon Hamilton Amateur Astronomers
Chair's Report
I often am tempted to say "Back
in my day ..." these days. You
don't really appreciate how very
much things have changed until
you look back a decade (or two!)
It is easy to complain that the
skies have gotten much brighter
they have! But there have been
many improvements which at
least partially compensate for
these brighter skies. Let me list a
few.
Eyepieces. Back in my day, the
way to a wide field was
something called an Erfle. Never
heard of them, you say? They
were the things we used before
the words Nagler and Panoptic
made it into the lexicon. The field
was wide, alright. Too bad the the
stars in the outer half of the field
all looked like progressively
larger seagulls! You want high
power in the winter? Get your
cornea nice and close to the tiny
lens in the 4mm Orthoscopic.
Then breathe heavily to unfreeze
it.
Nebula filters. What a concept!
Filter out all the stray skylight
and let *all* of the nebular light
through. It works amazingly well,
even in the city. I never saw that
kind of contrast even from a dark
site in the "olden days".
Aperture! Why, when I was
young we used to lie awake at
night dreaming about what it
would be like to look through a
10 inch telescope with aluminium
coatings. Forget 20 inch and ultra
bright.
GOTO scopes? GPS scopes?
These weren't even a gleam in
anyone's eye! You starhopped.
That wasn't a bad thing, of
course, but it isn't nearly as
amazing as pressing a button.
Astrophotography? Get a nice
fast film like Tri X ASA 400.
"Push process" it. Today's
affordable CCD astrocameras
have speeds equivalent to ASA
16,000! And they even auto
guide!
Some things really do improve
with time. We know much more
now and many even more
interesting things are in the
works. It is sometimes attractive
to hark back to more simple
times, but things WEREN'T
better in every way in the past.
That is one of the things which
makes this such a great hobby it
is progressive. There are MANY
different ways to experience it
and enjoy it. I hope the members
of the HAA continue to enjoy
riding this exciting wave. I know
I certainly do!
Doug Welch
Doug Welch is the current chair of the HAA and also a
founding member.
You can find out more about Doug at:
http://www.physics.mcmaster.ca/people/faculty/Welch_DL_h.html
Event Horizon is a publication of
the Hamilton Amateur
Astronomers (HAA).
The HAA is an amateur
astronomy club dedicated to the
promotion and enjoyment
of astronomy for people of all
ages and experience levels.
The cost of the subscription is
included in the $25 individual or
$30 family
membership fee for the year.
Event Horizon is published a
minimum of 10 times a
year.
HAA Council
Hon. Chair Jim Winger
Chair Doug Welch
Second Chair Grant Dixon
Secretary Margaret Walton
Treasurer Barbara Wight
Obs. Dir Stewart Attlesey
Publicity Sheila Overall
Editor/Web Anthony Tekatch
Membership Dir. Ann Tekatch
Councillors
Ray Badgerow
Web Site
http://amateurastronomy.org/
Mailing Address
PO Box 65578
Dundas, ON
L9H 6Y6

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Event Horizon Hamilton Amateur Astronomers
I would like to thank Rosa
Assalone for her tireless efforts in
creating the newsletter since
1998. I have volunteered to take
Rosa's place and hopefully will
be able to do as good of a job as
her.
You may notice some changes in
the newsletter layout since I am
using different tools, please let
me know what you like/dislike.
Also, the calendar of events is
now a monthly calendar sheet
that you can hang on your wall.
I've written a Python program to
insert the Jupiter Great Red Spot
sighting times. Drop me a line if
you have any ideas or events that
you'd like to appear in the
calendar. This months edition
includes February's and March's
monthly calendar but the March
newsletter will only include
April's calendar.
This months edition was created
using "Scribus 0.5.4" for Linux.
Although it is beta software it is a
workable free product. The
calendars were produced with
"pcal". Maybe I'll try to use
LaTeX next month, beware.
Anthony Tekatch
anthony@unihedron.com
Ask the Experts
If you have any questions about astronomy we have experts in the following fields that
are ready to answer your questions:
galactic astronomy
astrophysics
stellar physics and variables
astrophotography using emulsion/print film
polar aligning an equatorial mount
scanning photos and image processing
Send in your questions to anthony@unihedron.com
This month's Q&A theme ... Gravity
Sucks
Q. I have been reading about the four
major moons of Jupiter and I am
surprised by the amount of extreme
variation there is between them. One is
volcanic, another is ice capped with
possible liquid water beneath, others are
dry and rugged. What is the reason that
they are all so different, being satellites
of the same planet? From Brian Chire
A. The answer to this problem becomes
much clearer if we arrange the four
Galilean Moons in order of their
distance from the planet Jupiter. As we
start at Io, and proceed outward through
Europa, Ganymede, and finally Callisto
we will see the satellites' surfaces take
on a more stable appearance. This is the
direct result of gravitational tidal
interaction with Jupiter. The closest
satellite Io is under the greatest tidal
strain and shows the most dynamic
surface, while the furthest satellite
Callisto is under the least tidal strain and
therefore exhibits the most stable
surface. By Astro Crackerjack
Q. I read that there are a very few
number of satellites of planets moving
in a "retrograde" direction around their
planet. This implies to me that most of
the bodies in the solar system all revolve
in the same direction around the sun or
planet. If so, why is this so, and why do
those few bodies move in the other
direction? Do the same directional
movement rules apply outside of our
solar system? From Brian Chire
A. Of the sixty four or so satellites in the
solar system only eight move in
retrograde orbits. It would appear that
the solar system is moving in one
direction and this is indeed so. We have
to go back to the birth of the solar
system, to a time when there was
nothing but a massive cloud of gas and
dust. For whatever reason this cloud
started to collapse with a slight spin. It
may have had the spin before it
collapsed or the event that triggered the
collapse imparted a spin. Gravity
became the driving force in the collapse
and as the cloud became more compact
potential energy was translated into
angular momentum. The system sped
up and gravitational effects along with
angular momentum caused all objects to
move in the same direction. It would
seem from observation and from
deductive reasoning that this effect is
general. I should point out that this is a
simplified version of reality and the true
scenario is much more complex. The
more interesting question is How did
the retrograde objects come into being?
and that is another whole story. By
Astro Crackerjack
Q. It is my understanding that all
From the Editor
cont pg 4 ...

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Event Horizon Hamilton Amateur Astronomers
galaxies rotate. Do they all rotate the
same direction, and if so, why? If not,
why do some rotate one way and some
the other? Brian Chire
A1. There is no answer to this question.
It all depends on your perspective.
Looking at the galaxy from one side will
show it rotating one way and from the
other side it will rotating the other way.
Who can really say which way it is
rotating? Stewart Attlesey
A2. It isn't really possible to tell if all
galaxies rotate one way or the other
since that would presuppose that there's
an actual top and bottom to a galaxy.
There is a relative top and bottom from
the perspective of a particular observer
(you, for example), but someone
viewing from another angle may
perceive what you call the top as the
bottom.
What is interesting, though, is that no
matter what type of galaxy you're
looking at they all rotate. The most
obvious ones perhaps are the spirals with
their pinwheel pattern which give the
impression of spinning by just looking at
them. Less obvious are the elliptical
galaxies which don't have arms: they
just seem to be disks with a bulge some
bigger and some smaller in the middle
of them. Even less obvious are the
irregular galaxies: but they spin too.
How can we tell? When taking a
spectrum of various parts of a galaxy,
one generally notices that most galaxies
have a red shifted spectrum (there's a
handful that don't). That is, each part of
the spectrum of the galaxy is shifted
towards the red end of a reference
spectrum by some constant amount.
However, if you look at the relative
amount of redshifting in different parts
of the galaxy, some parts are a bit more
redshifted and some parts are a bit less
redshifted. If you subtract the average
redshift value from all your different
spectra measurements, what you'll
notice is that one side is blue shifted
(approaching) and the other side is red
shifted (receding). This is what you'd
expect if the galaxy was spinning.
Now, going back to the original question
and adding to the answer provided
above: An observer on the exact
opposite side of the galaxy from you
would perceive a blue and red shifted
side, but reversed. That's because what
you'd see as receding would be
approaching this other observer, and
vice versa. That observer would claim
the galaxy is spinning in the opposite
direction you would. Who's right?
Both of you it's a matter of perspective
and there's no absolute frame of
reference to decide one way or the other.
Tom Steckner
Q. With respect to the previous question.
What about looking at all galaxies from
the edge of the universe, are the spin
axis at different (random) angles to each
other? Anthony Tekatch
A1. As far as I know there is a fully
random distribution of just about every
parameter you can think of, including
rotation. By the way, I don't think you
can say there is an edge to the universe.
If you travel half the distance to what we
perceive as the limit of the universe, in
any direction, when you get to that point
the universe will still have the same
distance limit in all directions. In other
words, we can only see as far as light
has had time to travel since the universe
was formed but the universe is larger
than that! The inflation theory accounts
for the initial expansion of the universe
at a speed faster than light. (IIRC)
Stewart Attlesey
A2. There actually is no "edge of the
universe." I don't know how to explain
that other than to provide the analogy I
once read. Ones perspective of the
universe is something like standing on
an imaginary balloon covered in dots
(galaxies), with you standing on one of
the dots. You can look in any direction
and see dots (galaxies), but there's no
edge. Further, the expansion of the
universe can be visualized by what you
would observe while standing on the
balloon as it is being filled: the space
between the dots increases as they
recede from you, but there's still no
edge. Unfortuantely this analogy can
only show this effect in two dimensions.
The "edge" sometimes described in the
newspaper articles in connection with
missions looking at the cosmic
microwave background (CMB) such as
COBE and recent experiments based in
the Antartcic is a bit of a misnomer. It is
simply an edge from our perspective
because as you look ever farther into the
universe, you are also looking back in
time. Eventually you get to the point
where you're looking far enough away,
and hence far enough back in time, that
galaxies haven't even been formed yet.
Look back far enough (in space and thus
time) and you're looking at the leftover
energy from the Big Bang; i.e., the
CMB. From our perspective, this is an
edge. However, if there was someone
looking back at us from that position
they would not see you they'd see the
CMB too since the only signal from our
part of the universe which is old enough
to have reached them is from the era you
are seeing them in their patch of the sky.
So, getting back to the original question,
are the spin axes random? Yes, but
there's no "edge" against which to
compare this your perspective from our
Milky Way is as good a place as any
from which to observe and draw this
conclusion. Tom Steckner
... cont pg 3

Page 5
Event Horizon Hamilton Amateur Astronomers
On Groundhogs, May Poles and
Turnips
What do Groundhog Day, May
Day and Halloween all have in
common? They are all cross
quarter days. Cross quarter days
are those days that are exactly
half way between the equinox
and solstice (or vise versa).
There are four of them (the fourth
one being Lammas). In old
Germanic and Celtic traditions,
the equinoxes and solstices
marked the middle of the seasons.
Resulting in the cross quarter
days marking their beginnings.
Because of this, these days had
great importance in these cultures.
Groundhog Day (Feb 2):
The current name for this holiday
is an Americanization of the old
holiday called Candlemas.
Candlemas is the feast day of
Brėghde (or Bridget), the Celtic
goddess of fire. In some
countries it was believed that
some type of burrowing animal,
normally a hedgehog, would
come out on Bridget's Day to
judge the quality of the weather
as per the following saying:
Candlemas is fair and clear
There'll be twa winters this year
This tradition came with the
settlers to North America, but
Holidays by Charles Baetsen
since no hedgehogs could be
found, groundhogs were used
instead. The above saying was re
written as:
If the groundhog sees his shadow
we will have six more weeks of
winter.
Groundhog Day is precisely half
way between the Winter Solstice
and the Vernal Equinox. It
should be noted that, regardless
of whether the groundhog sees
his shadow or not, from a
mathematical point of view, on
Feb 2, there are always six weeks
of winter left!
May Day (May 1):
May Day was originally called
Beltane for the Celtic god
Belenus. It is exactly half way
between the vernal equinox and
the summer solstice. It was a
time of fun and games. In ancient
times, lovers would sleep
outdoors and celebrate the "great
rite" (use your imagination) in the
fields to ensure the fertility of the
crops. The Druids and their
successors raised the Beltane fires
on hilltops throughout the British
Isles on May Eve (the Celts
began their daily cycle at sunset).
In later times these fires were
replaced with the maypole.
Dances were (and still are) done
around the maypole during the
day. May Day came under severe
attack by the Puritans who
banned it by an act of Parliament
in 1644. May Day did return
with the restoration of Charles II
in 1660, but the elements of
sexual license and social reversal
went underground. Since the
Puritans frowned on May Day, it
has never been celebrated with as
much enthusiasm in North
America.
Lammas (Aug 1):
This cross quarter day has all but
disappeared from the modern
calendar. It occurs exactly half
way between the summer solstice
and the autumnal equinox. In
Northern Europe, summer was
considered to end at this time, as
the days grow visibly shorter.
The Celts honoured the god Lug
(god of light) on Lughnassad.
Eventually, this holiday became
Christianized to become Lammas
or the "Feast of the Loaf Mass".
This is when early grain would be
baked into loaves and offered at
mass. A ceremonial highlight of
this festival was the "Catherine
Wheel" (St. Catherine's feast day
was also on Aug 1st). A large
wagon wheel was taken to the top
of a near by hill, covered with tar,
set aflame, and ceremoniously
rolled down the hill, symbolizing
the end of summer. The flaming
disk represented the sun god in
cont pg6 ...

Galileo Completes Last Io Flyby
On January 17th, the Galileo
spacecraft made its final flypast of the
volcanic moon Io,on the I33 orbit. The
probe came with 1.5 km of it's aimpoint
and arrived 5 seconds later than
expected. This flyby was targeted to the
Jupiter facing hemisphere which was not
viewed on previous orbits. The
command sequence was stopped about
half an hour before closest approach
(100 km) due to a radiation induced
safing event ,and most of the Io
observations were lost. However,
Page 6
Event Horizon Hamilton Amateur Astronomers
Charles Baetsen is
a founding member
of the HAA. He
moved to
Peterborough a few
years ago with his
wife and three kids. Charles is
editor of the Peterborough
astronomy club newsletter.
his decline.
Halloween (Oct 31):
Today this is the best known of
the cross quarter days. The Celts
celebrated Samhain (or summer's
end) on this day. By summer's
end they meant that it was the end
of the warm part of the year (keep
in mind that Europe's weather
moderated by the gulf stream).
Samhain occurs exactly half way
between the autumnal equinox
and the winter solstice. This was
the Celtic New Year. The Celtic
festival of Samhain was
celebrated at the same time as
Pomona, a Roman celebration of
the harvest. After the Roman
conquest of Britain in 43 AD,
these two cultures began to merge
and bobbing for apples (pommes)
and harvests became part of the
celebration. In 835 AD, the
Catholic Church declared
November 1st as All Saint's Day
(or Hallowmas). The previous
day then became known as All
Hallows Eve (or Halloween).
In old Europe, the wealthier
members of a community put
together lavish Samhain feasts for
their households. The poor
would take on the collective
identity of the community's dead,
and go from door to door to
receive offerings (treats) in the
name of their ancestors. At each
house they are given a portion of
the food that has been set aside
for the dead. Not to hand out
food for any reason was
considered an act of impiety, and
would invite retaliation in the
form of property destruction (the
trick). This was the origin of the
trick or treat custom we see
today. In order to see their way
... cont pg 5
at night, people made lanterns
from carved out turnips. During
the potato famine in the 1840s,
thousands of Irish Catholics came
to North America and brought
this custom with them. Since
pumpkins were more plentiful
than turnips, it didn't take them
long to start hollowing out Jack
O Lanterns.
Charles W. Baetsen
va3ngc@rac.ca
observations were made of Europa,
Amalthea, Jupiter,and distant views of
Io. The last remote sensing observation
made during the Galileo tour was a
NIMS calibration made on February
1st. The cameras were shut down after
that. The Galileo probe is now on a long
cruise phase, some 292 days, the longest
cruise period since orbit insertion in
Dec. 1995. It will fly past Amalthea on
Nov. 5,2002 in order to make a mass
determination. The mission will end in
September 2003 when the orbiter
plunges into Jupiter's atomsphere near
the equator.
Hubble Gets An Upgrade
Sometime in late February or March
the Hubble Space Telescope will get
another visit from the Space Shuttle to
have several of it's instruments upgraded.
During the next mission the Hubble will
have the Faint Object Camera(FOC)
replaced with the versitale new
Advanced Camera For Surveys(ACS).
In addition, there will new solar panels,
electronics,a new power control unit
cont pg7 ...

Grant Dixon is a founding member of the HAA. You can
find out more about his life and hobbies at:
http://home.cogeco.ca/~grant.dixon/index.htm
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Event Horizon Hamilton Amateur Astronomers
by Grant Dixon
When you are asked "told" to
write an article, you panic, you
have a fuzzy brain moment and
think, What to write?. Well, I sit
here with a blank piece of paper
and think what I should write
about. Should it be deep and
erudite, or light and whimsical;
should it be learned or
superficial? As I type I realize
everyone loves the trivial, so why
not something about the sun? I
have selected three short stories
about observing the sun: two
anomalies and one just a curiosity.
17th Century Solar Rotation
For almost a century the sun went
into a period of very low sunspot
activity now known as the
Maunder Minimum (1645 1715).
Just prior to this, there were two
well documented accounts of
sunspot activity. One was
between 1625 1626 and the other
between 1642 1644. In both
cases, astronomers were able to
ascertain the rotation of the sun.
The surprising finding was that
just before the Maunder, the sun
rotation sped up by 3%. As far as
I know no one has been able to
successfully explain this
phenomenon!
Rapid Surface Change
On January 22, 1900 at 3:00 p.m.,
Caroline E. Furness was using the
observatory at Vassar College to
observe the sun. She observed a
sun devoid of spots for 15
minutes and then suddenly a spot
appeared. The sun was then
projected onto a screen to make
an image of 15 inches in
diameter. The spot was now the
size of a pinhead and while she
observed this one, another and
then another appeared, and finally
a fourth appeared. Within 10
minutes all had faded with the
exception of the first one. At that
time the sun was getting so low
the observing session ceased.
When Furness returned to
observe the sun the next day there
were no spots. While the solar
surface is very active, I am
curious as to why this is the only
observance of such a rapid
change of sunspot activity.
Fly Me Swiss Air
On January 22, 1959 Yngve
Ohman, while observing the sun
at the Stockholm Observatory,
noticed a black object cross the
sun. It created a light surge that
lasted two seconds and extended
two minutes of arc on either side
of the sun. A month later a
colleague of Dr. Ohman made a
similar observation. This caused
a great degree of puzzlement until
someone thought that maybe it
was the crossing of planes. The
Swiss Air force was coaxed into
supplying two jets to take part in
an experiment. The jets made
two transits at a distance of about
10 km and the results were
consistent with the earlier
observations; therefore, the
hypothesis was proven to be
correct. To my knowledge this is
the only time fighter jets have
been used in a scientific solar
experiment.
Science 198:824 829, 1977
Popular Astronomy, 8:109, 1900
Sky and Telescope 19:472, 1960
,and a cryocooler and radiator for the
NICMOS insturment. We can expect to
see new and exciting images from the
HST over the next several years. For
details see the March 2002 issue of Sky
& Telescope.
by Ray Badgerow
... cont. from page 6 (Space News)
Raymond Badgerow is a member
of both the HAA and RASC
Hamilton Centre. He served as
both recorder and librarian for the
Hamilton Centre,and is on the
HAA board. His email is
rbadgerow@mountaincable.net .

Page 8
Event Horizon Hamilton Amateur Astronomers
Answer; Probably.
The nature of black holes
makes it difficult to say with
total certainty that they are
real. Theory and indirect
evidence make a very strong
case for their existence
however.
When a star runs out of fuel
and can no longer produce
enough energy to counteract
the force of gravity it will
collapse. This can take place
over a very short period of
time and with great violence
as a supernova or it can be a
relatively gentle process.
The fate of a star is primarily
governed by its initial mass.
(Having a companion adds
some different scenarios to
this process.) A high mass
star, greater than 8 times the
mass of our Sun, will most
likely end its life as a
supernova. Smaller stars
such as our Sun will have a
much quieter fate perhaps
going through a planetary
nebula phase. In both cases
the star will lose much of its
outer layers. The mass of the
remaining inert portion of
the star determines its final
fate. Up to about 1.4 solar
masses, the Chandrasekhar
limit, the core will compress
down to a white dwarf.
Further compression is
prevented by electron
'pressure'. At higher masses,
gravity overcomes electron
pressure and protons
combine with electrons to
form neutrinos and neutrons
with the end result being a
neutron star. Neutron
'pressure' can limit
compression up to about 3
solar masses. Beyond this
mass there is nothing known
that will halt gravitational
collapse. The star, in theory,
will collapse to a point with
zero size! This is called a
singularity and the gravity is
so high that nothing, not
even light, can escape. Black
holes appear to have a
physical size though due to
an 'event horizon'. To
understand what the event
horizon is, imagine that you
are throwing a ball straight
up in the air at 100
kilometres an hour.
Eventually gravity will pull
the ball back to the surface
of the Earth. Now step into
an elevator that can take you
hundreds of thousands of
kilometres away from the
Earth. You will find that as
you travel in this elevator
you can throw the ball
higher and higher before it
returns to you. Eventually
you will reach a point where
the 100 kilometres an hour
velocity of the ball is enough
to overcome Earth's gravity
and it will keep on going.
Now consider light, which
travels at 300,000 kilometres
a second. It doesn't have
enough velocity to escape
the pull of gravity at the
center of a black hole. As
you move away from the
center you will eventually
reach a point where, just like
the ball, it can escape. This
distance defines the radius of
the event horizon. Looking
at a black hole from the
outside, the event horizon
would appear to be its
'surface'. It is merely the
point closest to the star that
anything surrounding the
black hole can still be
visible. Since a black hole is
by definition black, there is
nothing to observe.
However, we can see the
effects that such massive
compact objects have on
their surroundings.
What distinguishes black
holes from ordinary objects
is high mass in a very small
volume and this feature is
used to deduce their
presence. So how do you
weigh an object like a star?
Using our solar system as an
example, if a planet moves
around the Sun in an orbit
with a radius r and velocity v
you can use the formula
M=(rv 2 )/G. Where G is the
gravitational constant and M
is mass.
For our Sun we can calculate
a mass of
Do Black Holes Really Exist? by Stewart Attlesey
cont pg 9 ...

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Event Horizon Hamilton Amateur Astronomers
2 x 10 30 kilograms (that's a
2 followed by 30 zeros!)
The trick to solving this
equation for potential black
holes is determining the
radius and velocity of
objects orbiting it. The
velocity can be measured by
looking at how the light of
orbiting stars is Doppler
shifted. This won't work
with a system oriented to us
like the above example since
both objects remain the same
distance away from us at all
times. For an edge on
system, a star approaching
us appears bluer, and
receding it appears redder.
The higher the velocity of
the stars the greater the
change in colour. To obtain
the radius we can measure
how wide the orbit appears
to us and calculate the radius
knowing the distance. To
determine the distance of
relatively nearby objects we
have to rely on using
associated objects of known
brightness. Measuring the
apparent brightness of these
objects and knowing how
bright they actually are
allows us to make this
calculation. For objects that
are very far away we can use
the redshift value and the
Hubble constant to estimate
their distance. In other
words, the farther something
is away from us the faster it
is receding from us.
Here is an example using the
galaxy NGC4261 located
100 million light years away
in the constellation Virgo.
Inside the core of this galaxy
is a disk that has had its
radius and velocity
measured. When the
calculations were done it
was determined that the
object at the centre is about
as large as our solar system
and weighs 1.2 billion times
the mass of our sun. There is
nothing currently known
other than a truly massive
black hole that can satisfy
these conditions.
Another example is the
galaxy M87.
Once again, the core of the
galaxy contains an object no
larger than the diameter of
the solar system and weighs
3 billion times as much as
the Sun.
So even though no one has
ever seen one it looks like
black holes really do exist.
... cont pg 8
Stewart Attlesey is a
founding member of
the HAA. He has held
the positions of Chair,
Editor, Secretary,
Recorder and is currently the
Observing Director. He has also
held the positions of Recorder
and Observatory Curator for the
RASC Hamilton Centre.
(stewart.attlesey@cogeco.ca)

Page 10
Event Horizon Hamilton Amateur Astronomers
In Sight
Snowflakes fall, and the wind blows
Ice pellets knock on my windows
What a contrast just days ago!
The full moon crowned with a halo
With Jupiter at her side
Glowing brightly, with pride
How quickly everything changes!
The cosmic scene rearranges
Hot becomes cold, clear becomes cloudy
New becomes old, quiet becomes rowdy.
The earth turns. Life grows, by chance?
Our hearts yearn for immortal dance.
Many secrets yet untold
Answers we try to mold
Our minds put to the test
Joy felt in the quest
And beauty to behold
As the cosmos unfolds
Barb Wight
Photo
by
Stewart
Attlesey.
It
shows
a
halo
around
theMoon
and
Jupiter.
Jupiter
was
3
degrees
west
of
theMoon
on
January
26,
2002.
Ice
crystals
in
high
clouds
produce
a
22
degree
radius
halo.
The
clouds
and
the
exposure
required
to
show
the
halo
rendered
theMoon
featureless.
Phot
specs:
Canon
G2,
Focal
length
7mm
(equivalent
to
34mm
in
a
35mm
camera),
f/2,
1/8
second,
ISO
50
Here
is
a
great
link
that
talks
about
halos:
http://www.sundog.clara.co.uk/atoptics/phenom.htm

Page
Event Horizon Hamilton Amateur Astronomers
appears to us and calculate the radius
knowing the distance. To determine the
distance of relatively nearby objects we
have to rely on using associated objects
of known brightness. Measuring the
apparent brightness of these objects and
knowing how bright they actually are
allows us to make this calculation. For
objects that are very far away we can use
the redshift value and the Hubble
constant to estimate their distance. In
other words, the farther something is
away from us the faster it is receding
from us.
Here is an example using the galaxy
NGC4261 located 100 million light
years away in the constellation Virgo.
Inside the core of this galaxy is a disk
that has had its radius and velocity
measured. When the calculations were
done it was determined that the object at
the centre is about as large as our solar
system and weighs 1.2 billion times the
mass of our sun. There is nothing
currently known other than a truly
massive black hole that can satisfy these
conditions.
Another example is the galaxy M87.
Once again, the core of the galaxy
contains an object no larger than the
diameter of the solar system and weighs
3 billion times as much as the Sun.
So even though no one has ever seen one
it looks like black holes really do exist.
... cont pg 4