There
were so many
great image submissions this month it was very difficult to choose
between them. Before I start, I'd like to take a moment and thank
everyone who submitted.
Thank you.
I wish I could have found a way to use them all.
And now, on with our regularly scheduled programming.
If there's one constellation known to astronomer and non astronomer,
young and old, it would have to be
Orion. It was the first constellation that I learned to
pick out of the night sky. I'm not exactly sure where I first
learned about this celestial nimrod, but I have dim recollections
of
being on a camping trip, and my father guiding my gaze into the
cool late winter / early spring sky while talking about Orion's
belt.
Of course, Orion's belt is only one small portion of the Hunter that
has found it's way into the night sky. The figure of Orion
holding a shield while raising a club is pretty easy to see, so it's no
surprise that the history of this constellation
goes back a long way. The great celestial hunter is doomed to do
constant battle with Taurus the bull while Lepus the hare crouches
at his feet, and his dogs are off getting into the trouble you
would expect dogs to get into. I suspect if you look closely
enough, they are probably eyeing Pisces - many's the dog whose come
home smelling of dead fish, and I wouldn't expect these celestial
hounds to be any different. (As an aside, I've always had half a
thought we should
rename Lepus, Orion's Lunch - but I digress.) In another
version of the Orion Mythos, Orion was placed in the sky in an act of
pity by Zeus, after being stung to death by Scorpius - the
Scorpion. In the tradition of gun shy heroes everywhere, Orion
now
flees from the scorpion night after night (or chases the creature if
you prefer
your heroes valiant - and a bit more traditional.)
Today, I know a
little bit more about Orion than I did the first time I saw him, but he
and his belt are no less
impressive. Especially when you consider that the three
stars that make up the belt - Alnitak, Alnilam and Mintaka (labeled
as delta on our widefield chart above) are all members of the same
cluster (Cr 70), which resides 1500 or so light years
distant, and each of these three are somewhere
around 20,000 to 40,000 times as bright as our sun. These three
blue white stars and the associated cluster are a signpost for any
amateur learning their way around the night sky.
Two other stars of note (and worth a glance) are alpha Orionis and beta
Orionis. Alpha, is more commonly known as Betelgeuse and is one
of the
true giants of the night. This bright orange supergiant, lies 425
light years away and has a diameter of nearly 270 million miles.
If placed at the center of our solar system, it would eat up the inner
solar system without batting an eyelash. Depending on whom you
listen to, Betelgeuse is a corruption of the Arabic for Armpit of the
Giant or Hand of
the Giant.
Rigel, on the other hand, is a blue supergiant. Although
it's designated Beta, Rigel is the brightest star in Orion, and the 7th
brightest star in the night sky. Rigel is
accompanied by a companion star of 7th magnitude, but it can be
somewhat difficult to
detect visually because of it's proximity to the super bright
Rigel (it's around 400x dimmer). It's a good test of a small
scope, and a fine sight. The best I've managed with this
celestial odd couple was splitting it with an 80 mm APO at
around 90x under decent seeing conditions. I suspect I would have
been able to go a bit lower if I had the appropriate eyepiece, and I've
heard of a Pronto owner splitting it at ~68x. Don't be distressed
if it takes significantly higher power to split - some observers from
the 33 Doubles Observing Project report it required powers in excess of
150x.
Orion is such a well known constellation, it's almost hard to pick a
place to start
this month's tour. He's home to open clusters, reflection nebula,
supernova remnants (the famous Barnards Loop), dark nebula, planetary
nebula, galaxies (some 3000
turn up in a quick search), more than a dozen galaxy clusters
(Hickson 34 is
probably the best known) and just about every example of the celestial
zoo you could imagine. However,
without a doubt, the best known target in this heavenly nimrod has to
be his namesake nebula.
M 42 / 43
Marking the middle
of Orion's sword, the M 42 region is visible to the naked eye,
obvious in binoculars, and spectacular in nearly any size
telescope. This is one of the few nebulae that you can actually
see color in - assuming you have a large enough telescope. I've
caught glimpses of pink and salmon in an 18" - the only time I've ever
seen that hue in the night sky.
Regardless - if you are looking at it in a 3" scope or a 30"
scope, it's still an awe inspiring sight. At moderate powers in
my 4" refractor, it fills the field - wisps of
nebulae reaching to and fro
across the field of view (east being to and west being fro - technical
terms don'tcha know).
I have spent many many hours in the cold of winter just
staring at the Great Orion Nebula. No matter the telescope, this
stellar nursery never seems to loose it's magic. In many
ways, a visual view is more appealing than a photograph, because the
increased dynamic response of the eye enables you to make out details
that would often be overexposed in a camera. Case in point,
Orion's celebrated multiple star system located in the heart of M 42 -
the Trapezium (theta Orionis). There are four bright
components, at
least two dimmer ones that are visible in moderate to small
apertures. Named not for their magnitudes but their order in
right ascension, A, B, C, and D are visible nearly every clear night,
but I've found that I need a magnification of at least 21x to
split the trap into it's four main
components. On a night of good seeing you may be able
to pull out the E and F stars - at 11th magnitude, they really aren't
all that dim, but the combination of the bright background of the
nebula and the close proximity of the stars make it a rather tricky
proposition with small apertures. While they are easy in a ten
inch scope, I've heard of folks pulling out the E star with apertures
as small as 85 mm. I've never managed it with a scope this small,
but it has been my experience that E is easier than F.
While you are staring at M 42, look slightly northwards (above in
most cases) to see M 43, the smaller wisp of nebula that
separated from the main body by a tiny patch of black (at least in
smaller scopes). Then move slightly north again to glimpse
Orion's Crown.
NGC 1981
Why Orion insists on wearing his crown on his sword is beyond me, but I
can see it clearly in this open cluster. A moderate power
view reveals this nice asterism enclosed in NGC
1981. I've yet to hear anyone else referring to this as Orion's
Crown, but it's such an obvious asterism so close to one of the most
viewed treasures of the night sky, that in all honesty I can't believe
that I'm the first one to name it thus.
While there's no paucity of material in this area of the constellation,
it's now time for us to move north a bit and focus on a new area -
Orion's
belt.
.
There are multiple
targets of interest in this area, but as visual observers, our main
ones for the evening are M 78, NGC 2071, and Cr 70. NGC 2024 and
IC 434 are spectacular and well known , but probably out of the reach
of many
small scope owners.
In the region I've always thought of as Orion's Dagger, we find NGC
2024 (the Flame Tree nebula), and IC 434. IC 434 serves as the
backdrop for B33 - possibly the most famous dark nebula in existence -
the Horse head. While it's not really much of a
visual target for the typical small scope owner it's well known to
nearly
everyone who has ever shown the remotest interest in astronomy.
Pictures abound.
The accompanying H alpha photo of this region was taken by Jeff Thrush
through a 70 mm Pronto. To be frank, while I've seen better
pictures, I've never seen one this good through a scope this
small.
While they aren't on our target list for the evening, you might as well
take a gander at the areas
labeled on the map for 2024 and IC 434 - just in case. I've often
wondered what is
the smallest aperture that will allow a glimpse of the Flame Tree
and/or Horse Head.
I've heard vastly differing sizes, and am curious to hear what, you,
the
readers have to say. Collin Smith informs me he's caught the Flame Tree
in his 6" dob. I've never really tried for either in anything less than
10". My notes indicate that the Flame Tree was visible in my 10", but
the horsehead was not - at least from my location. I suspect you need
16+ inches and good skies to grab B33. Even though it's not a
Small Wonder,
consider these "extra-curricular" assignments. IC 434 (the
backdrop for the Horse Head) is one of two
regions an Hb filter is said to be helpful to visual observers (the
other is the California nebula).
Collinder 70
For this next
target, we need to pull back.
WAAAAYYYYY back. This is probably one of the few targets I'll
cover in
this column that actually looks better in binoculars or naked eye than
with a telescope.
When you are pointing out Orion's
belt to your children what you are actually pointing to is the open
cluster Collinder 70 (CR 70). I've scanned this area many many
times with a small telescope and always been pleased by the view, but
never actually saw this as a cluster until I pointed an inexpensive set
of 8x40 binoculars at it. While the richness of the star field
makes for an interesting sight in a small scope, the extremely wide 6-7
deg field of view of the binoculars sets it off as a star
cluster in it's own right, rather than a star rich region of the night
sky.
The three bright stars in the accompanying DSS image are of course,
Alnitak, Alnilam and Mintaka (delta), note the Flame Tree and a hint of
the Horse Head at the bottom left.
With a widefield eyepiece, now scan up and just to the east of Orion's
belt for our last Messier object in Orion and it's
companion.
M 78 and NGC 2071
While M 78 and NGC
2071 look spectacular in the
accompanying photo, I've never found them to be all that visually
interesting. They can be difficult to locate in a 3 inch
scope under a half moon, yet they none the less stand out in larger
scopes
under darker skies. I've found that light pollution is the real
killer for these
two - however, seldom have I looked for 78 and not been able to see NGC
2071.
Both look like small featureless wisps of light, but 2071 is smaller
and marked by an off center but fairly bright star.
The proximity of the two makes for a pleasing sight in the
eyepiece.
In contrast to my views of the pair, Steven James O'Meara finds a fair
amount of detail in this neglected object. Spend some time and
make your own detailed investigation. Try using different
powers and filter
combinations. What features can you see in M 78?
I've found that I need to use moderate to low powers with small scopes
as more magnification simply makes both nebula vanish. An
interesting challenge would be to see if you can pick these up in a
standard set of binoculars - say 8x40. If you can, I'd be most
interested in hearing about it.
At this point, we're done with our investigations of Orion's belt, so
let's mosey up his body once again.
Collinder 69
This is a wonderful
and yet woefully neglected cluster
for small telescopes. I've found many of the Cr clusters to be
particularly suited to small telescopes. They tend to be large
scraggly things without much central condensation, and like Cr 70, Cr
69 follows that pattern quite well.
It's an easy naked eye object from a moderately decent site, and thus
particularly easy to find - just point your
telescope at the fuzzy patch that makes up Orion's (somewhat
undersized but we won't hold that against him) head.
It's not that it's particularly rich - it's not. Nor is it
particularly colorful - it's not that either.
It is, however, striking. There are six bright stars that stand
out from the field well in a small telescope. Three bright ones
in a line, and then a smaller set of three with similar orientation and
spacing - but slightly smaller to match the decreased magnitude of the
stars. If you turn your head just right, it
may remind you of the binocular view of Cr 70 further south.
NGC 1662
Our last NGC cluster on the list this month, 1662 is an easy find at
the tip of Orion's shield (or bow - your choice).
With a wide field eyepiece, simply scan up the shield until you see
1662 just off the tip. This cluster easily stood out from the
background in an 80 mm scope working at a mere 14x. Larger scopes
might have more of a problem pulling it out from the background so you
may want to pinpoint it's location with an optical finder or a set of
binoculars first.
I found that I preferred low magnifications when viewing this cluster.
My best views in the 80 mm were at 14x and 28x.
While it's not a particularly rich cluster, it is a rather nice
loose grouping of a dozen or so stars in a small scope, and well worth
a look.
Challenge Object - NGC 2022
Did you know there's
a fairly bright planetary nebula in Orion? It's our challenge
object for this month. It resides just south west of Cr 69
(Orion's head) and is roughly located in Orion's
right shoulder.
As I mentioned, it's relatively bright and thus should be an easy catch
in a 6 or 8 inch
telescope under dark skies, but it is very small. Once you've
hopped to the correct area use the eyepiece chart to confirm your
location and then bump up the magnification to spot the
planetary. You may want to try an OIII filter if you have one in
your stable. Planetary nebula usually respond well to that type
of line filter.
And finally, Matt Russell was kind enough to submit this stunning image
of M42. Matt's image is particularly noteable in that he shows
the furthest reaches of the nebula as well as the Trapezium at it's
heart. Matt notes this is a 7 image mosaic with a 16" RCOS
Ritchey-Chretien for a total of 16 hours of exposure time.
You can find the full size image at:
