Canes
Venatici is a somewhat small constellation, and
may be difficult to find. Flanked by both Ursa Major and
Bootes, Canes is located in a somewhat barren section of the night
sky. Canes (whose name means The Hunting Dogs) has been seen as
Bootes pets for at least several
hundred years, but the constellation may not have been "stand alone"
until sometime in the late 17th century when Hevelius named (and
perhaps separated from their "parent" constellation) these celestial
dogs Asterion and Chara.
Probably the most impressive star in Canes is Y Canum
Venaticorum. Also called La Superba, it's a variable which
varies from 4.7 to 6.2 over a 158 day period. More to the
point for the casual visual observer is it's vivid coloration.
Located 700 or so light years away, it's one of the brightest carbon
stars in the night sky, and
shows a sharp red color to the slightest optical aid.
Although it's quite unusual to find open clusters so far from the plain
of the galactic disc, there is one open cluster in Canes - Upgren
1 (RA 12h 35m, DEC +36 degrees, 17 minutes) . Phil Harrington in
"Touring the Universe Through Binoculars" directs
our attention to a bright grouping of ten or so stars found five
degrees southwest of alpha. At a distance of only 380 light
years, Upgren 1 is one of the most ancient clusters known. Over
the last 3 billion years, Upgren 1's retinue of stars has slowly
dwindled to its present state - the rest being cast off throughout the
years. Upgren 1 was first identified by Rubin and Upgren in 1965.
There's also one
globular in Canes - the bright Messier M3.
M3 forms one vertex of a right triangle with Alpha Canum Venaticorum,
and Beta Coma Berenices, and is easily visible in a moderate finder or
binoculars as a 6th magnitude fuzzy star. Small scopes and
moderate to high powers are enough to generally resolve some of the
stars on the outer edge of the nebula as well as give a grainy texture
to the center of this fairly tight globular. Larger apertures
will yield better resolution. Curiously, notes with my 4" apo
hint at a yellow tint to many of the stars in the globular one evening
- but only at low power. Take a look and tell me what you think.
M3 image
courtesy of Gary Blevins
This is all well and good (ok, maybe in the case of M3, pretty
spectacular), but where Canes really shines is in extra galactic
DSO's. There are at least 367 Quasars in Canes, (with the
brightest at mag 15.2 though, we don't need to worry about it being a
target for our small telescopes) thousands of galaxies (a quick
search through known catalogs turns up 21615), and at least 87
Abell galaxy clusters and two Hicksons (68 and 70).
And so, it should come as no surprise that rest of the targets this
month are either galaxies or galaxy clusters.
We'll start with one
that's fairly easy to locate - NGC 4490.
Actually, what you're really looking at here is a pair of interacting
galaxies - 4490 AND 4485. Also called the Cocoon, this object is
located less than a degree WNW of Beta Canum Venaticorum. The
larger galaxy is also the brighter at mag 9.5, while 4485 is at
11.7. Thus it's quite possible, depending on the size of your
telescope and your sky conditions, you may not even pick up 4485.
This one has always seemed like a tortured object to me. Even in
smaller scopes there are lots of hints of detail. Spend some time at
moderate powers with this pair, and look for structure - particularly
in the area between the two galaxies.
NGC 4490
image courtesy Carl Burton
Up next, we take a
look at M94. A bright and interesting face on spiral, there are
debates as to just how much detail can be seen in a small telescope.
The 48" Schmidtt camera on Mt. Palomar has photographically picked up a
faint ring that runs
around the galaxy as a whole - seemingly disconnected. I've never
seen any hint of this in any size telescope I've inspected the galaxy
with, but O'Meara seems to think he might be picking it up with his
small scope from his pristine Hawaiian skies. Take a minute sweep
across the face of m94, moving the telescope while looking for it at
low powers.
Most of us will probably just see a fairly bright, somewhat irregular
galaxy that shows a bright star like nucleus - but you'll never know if
you don't try.
Next we come across
NGC 4449.
Discovered by William Herschel in 1788, 4449 is a dwarf galaxy
remarkably similar to "our" own Large Magellanic Cloud, and visually
presents sort of an irregular rectangle. The
population is rather young, as astronomers believe that many of the
stars found in the galaxies bar formation are not more than five
million years old.
In the DSS image, just off the northern tip of the galaxy, you'll note
a well defined hook shape. This is just one of the galaxies
HII regions. HII regions are currently active in
stellar formation.
If possible take a few minutes and inspect this one in different
apertures and make note of the differences seen when moving between
different size scopes. Can you spot the large HII region visually?
Our last galaxy in
this particular region is M106. Since the 1950's this galaxy has
been known to be a radio emitter, but it wasn't till 1994 a team of
radio astronomers confirmed a black hole near the galaxy's nucleus.
M106 lies some 22 million light years from us, and presents an
interesting sight for the patient observer. Even in small
telescopes elements of the galaxy's structure are hinted at - see if
you can pick out an s-curve (or three) hidden deep in this
active galaxy.
M106 was my personal lesson in comet hunting. Years ago when I
was scanning the region I stumbled across the galaxy, while I was
disappointed to find there would be no comet Trusock, I must admit my
independent discovery of M106 gave me a bit of a thrill for a while.
NGC 4631 - the
Herring or Whale galaxy is another favorite target for this time of
year. This large, edge on bright galaxy presents a nice target to
nearly any size telescope. I called it "Very Nice" in my 4", and
like many galaxies it's pretty spectacular in a large telescope.
In larger telescopes look for mottling, a notch on one of the tips,
and note the position of the central bulge. With larger
scopes, you might even be able to pick up the companion galaxy noted in
the picture.
M63 - the Sunflower
Galaxy - was discovered by Pierre Mechain - interestingly, it was
Mechain's first contribution to Messier's catalog. Mechain swept
this galaxy into his FOV on June 14, 1779. In the same physical
group with M51, M63 lies about 23 million light years away (depending
on your sources). Visually, in a 4" scope, I see it having
a somewhat grainy exterior, a brighter nucleus and hints of unresolved
arm structure. A foreground star is visible lying just off the
edge of the galaxy.
M63 image
courtesy Jim Thommes
M51 - the Whirlpool
- has to be one of my all time favorite
objects. I'm a resident of the 43 parallel, so it's visible for
me during a good chunk of the year, but there's no denying that late
spring / early summer puts this galaxy in it's best position for
observing. The distance to M51 is somewhere around 15 million
light years, and it's magnitude is usually given as somewhere
around 8.1 with a surface brightness of around 13th magnitude.
M51's spiral structure was probably first seen in 1845 by Lord
Rosse while viewing from his castle in Birr, Ireland, with his 72"
reflector - the Leviathan of Parsontown.
M51 is actually an interacting galaxy system - NGC5195 is the other
component, and they are connected visually by a stellar bridge.
There seems to be some debate on the visibility and actual
existence of the bridge. I've heard claims that it's a
photographic illusion and does not really exist, and yet it certainly
seems compelling to me. I've seen hints of the bridge in scopes
as small as 4" in aperture. It takes excellent
conditions, but this is one of those objects I look in on nearly
every observing session this time of year.
M51 image
courtesy Brian Ottum
I've seen hints of the spiral structure in scopes as small as 4", but
nothing really spectacular in telescopes smaller than the 8-10" size.
I distinctly recall one very transparent night with my old 10"
scope where the arms were easily visible. A 15" or 18" scope will
show spiral structure under nearly any conditions, and I was recently
blessed with a look at it through a 25" at a dark sky site. In
the 25" telescope, the arms took on a very well defined look and were
easily visible with direct vision. I've noted that for telescopes
somewhere around 15"-18", objects actually begin to look like their
long exposure photographs. In the case of M51, that's certainly
true - however, to me anyway, visually, they are much more striking.
I've found, (like anything else) visual detection of details like the
arms depends on observing conditions, and observer experience - don't
give up hope if you don't see detail your first, second or even 12th
time viewing the whirlpool. Put it on the list of objects to
return to over and over - this one's a crowd pleaser - and in a big way.
Don't think that you need a large scope to spot M51 however - by no
means. I've seen it through multiple sizes of binoculars and
small telescopes (under 4") as well.
M51 image
courtesy John Crilly
Here's a good
challenge object for a moderate sized telescope. This hickson has
5 components; NGC 5353, NGC 5354, NGC 5350, NGC 5355, NGC 5358 three of
which are 11th magnitude.
The three brighter, 5350, 5353 and 5354 should all be visible in an 8"
telescope from a moderately dark site, and could probably be a fairly
easy catch in a 6" scope. My good friend Ron B(ee)'s
managed to catch these three in his 4" TV102.
5355 and 5358 however, are both 13th magnitude faint fuzzies and will
probably require a significantly larger scope to snare.
There is a plethora of good objects in Canes that we didn't cover this
month. To that end, I'll leave you with an extra credit - a few
more nice targets to hunt down: NGC 4111, NGC 4143, and NGC 4244.
For full credit, be sure to e-mail me your observations.
Enjoy!
