The Messier objects that are at their highest in late-winter
evenings are less diverse than the early-winter objects; all
of them are open clusters. However, it is a fine and varied
lot of open clusters. Here are the objects from RA 6 to RA 9
excluding M35, which was covered in the preceding section.
For a key to this table, see
Key to the Tables.
In addition, many of the early-winter objects are well north
of the Celestial Equator, and so remain visible throughout
the winter to observers in the North Temperate Zone. Not
so for the late-winter objects, most of which lie south
of the Celestial Equator, and so are only well placed for
a short time for observers in the North Temperate Zone.
The disparity between the early-winter and late-winter objects
is no accident; it is due to the fact that the Milky Way slants
south-east through this part of the sky, passing through
Auriga, then between Gemini and Orion, and disappearing
for northern observers in the constellation of Puppis,
southeast of Canis Major. Open clusters and nebulae tend
to hug the plane of the Milky Way, so the farther east you
go in this section of the sky, the farther south the open
clusters and nebulae are found.
In striking contrast to the early winter Messier objects,
all of the late winter objects except for M41 are far
from bright stars, making them difficult to locate under
urban skies. I usually quote the limiting magnitude for
my urban sites at mag 4.6, but that assumes the use of
averted vision, knowing exactly where to look. Only
stars mag 3.0 and brighter really catch my eye; stars
between mag 3.0 and 3.5 are not hard to see, but require
some looking, and anything fainter than mag 3.5 requires
real effort. This part of the sky is dominated by the
constellations Monoceros and Cancer, whose brightest
stars are mag 3.8 and 3.9 respectively. That leaves an
enormous expanse of sky which at first glance appears
entirely devoid of stars. The "beacons" of the area are
Zeta and Chi Hydrae in the head of Hydra, at mag 3.1
and 3.4 respectively; it is worth spending some becoming
familiar with them. Take a look at Hydra's head in
binoculars; it is a wonderful asterism.
Under decent suburban skies, enough extra stars are visible
to make navigating this part of the sky a pleasant adventure
instead of a heroic exploit.
If you are planning to observe all of the Messier objects
and live in the North Temperate Zone, you would be well
advised to observe M81 and M82 at this time of year.
These objects are at their highest in the early spring,
and are described in that section of this guide. But
being the most northerly of all the Messier objects,
M81 and M82 are high above the horizon long before and
after that time for observers in the North Temperate Zone.
If you save all the galaxies for spring, you are likely
to be overwhelmed by them.
M41 is very big and very bright; in fact, it is readily
visible to the naked eye under dark skies if you live far
enough south for it to rise high above the horizon, and
it is fairly easy in my 7x35 binoculars even from my
city home at latitude 42N. It shows very well in my
70mm scope under urban, suburban and dark skies, but
it improves little if at all in larger telescopes; it
is not especially rich in faint stars. Because M41
is very big and somewhat vague, it needs a very large
field of view to set it off well against the fairly rich
background -- preferably 1.5 degrees or more.
I can usually find M41 fairly easily by the point-and-hope
method, aiming 1/3 of the way from Sirius to Epsilon CMa,
the bright star at the right-hand foot of Canis Major.
If that fails, the best bet is to star-hop from Sirius.
M41 contains three mag 7 stars, resolvable even in small
binoculars. True to form, two of those stars are near
the cluster's center, one strikingly red, and the other
appearing reddish yellow to my eye. I see about two
dozen stars using my 70mm scope in the city at 20X,
many at the edge of visibility, giving it a charming
air of mystery which vanishes in bigger scopes and
darker skies. Some 50 star are visible in my 178mm
scope at 28X under suburban skies, spread out fairly
evenly from mag 8 down to mag 11.
M50 is a modest but attractive cluster, fairly small and
fairly bright, and it stands out surprisingly well against
a very rich background, especially at higher powers.
It contains five or six stars brighter than mag 9.5, but
the majority of the stars are mag 11 or fainter. My 178mm
scope resolves the fainter stars well, but in my 70mm scope
they tend to merge into a nebulous background, which is
fairly prominent in the suburbs and rather subtle from
the city. M50 does best at high powers, 60X in my 70mm
scope and 120X in my 178mm. M50 is fairly difficult to
see in my 7x35 binoculars from the city or the suburbs.
The stars of M50 line up roughly in the shape of an
equilateral triangle, with four stars forming a tiny
horizontal Y in the center. The brightest star of the
cluster, near the south tip of the triangle, shows
strikingly red in my 178mm scope.
M50 is fairly easy to locate from Theta CMa at the top
of the Big Dog's head, but at mag 4.1, that star may be
impossible to see from northern cities due to its low
altitude above the horizon. Extend a line from Sirius
through Theta and continue 80% farther; there lies M50.
If you cannot see Theta, you must star-hop from Sirius.
M46 and M47
M46 and M47 are visible together in a 2-degree field, and
they form a wonderful contrasting pair. The two clusters
are almost identical in size, but there the similarity ends.
M47 is extremely bright, quite prominent to the naked eye
under dark skies. It is a fairly sparse cluster, dominated
by a handful of very bright stars. M46 is several times
fainter, very rich in faint stars, but with no bright stars
M47 contains 5 stars brighter than mag 7.5, all easily
resolved in my 7x35 binoculars under urban skies, let alone
in my 70m scope. Somewhat surprisingly, these stars do not
stand out all that well, due to the proximity of several
other similarly bright stars in the immediate vicinity.
About twenty stars are visible in my 70mm scope under urban
skies, enough to make the cluster seem convincing, although
still rather sparse. Darker skies and/or larger apertures
bring out another 20 somewhat fainter stars which help to
flesh out the cluster. M47 shows well at 40X in both of my
scopes, and this is also enough power to split the attractive
double star Struve 1121 at the center of the cluster, with
two almost equal blue-white components separated by 7".
M46 is an extremely rich collection of faint stars, quite
similar to M37, although the stars are little fainter and
more scattered than those of M37. Under dark skies, the
faint stars merge into a haze that stands out well in my
70mm scope and my 7x35 binoculars, and may even be visible
to the naked eye, but this haze is too faint for me to
see even in the suburbs, let alone the city. Under urban
and suburban skies, I can detect the cluster only when I can
resolve some of the stars, which is far beyond the capabilities
of my 7x35 binoculars, and also difficult or impossible in
my 70mm scope at low powers.
In my 70mm scope at 60X, only a handful of M46's stars
show from the city, most of those with averted vision.
Things improve considerably in the suburbs, with 12 stars
visible using direct vision and many more popping out
intermittently with averted vision.
M46 is still a little difficult using my 178mm scope at
low power in the city; I have scanned right over it at
40X without seeing it. But once I pinpointed the
location, a large number of stars were evident, some
visible with averted vision, some with direct vision,
but none bright enough to catch my eye unless I looked
carefully. The cluster improves greatly at 120X, where
numerous faint stars almost fill the field of view.
M46 really comes into its own using my 178mm scope
in the suburbs, where numerous stars are immediately
obvious both at low and at high powers.
At higher powers in my 178mm scope, the planetary nebula
NGC 2438 is faintly visible near the northern edge of the
cluster. It is hard to pick up under brighter skies,
but jumps out immediately with the aid of a narrow-band
filter, which erases many of the cluster's stars while
leaving the planetary nebula unchanged. This nebula is
believed to be an accidental superposition, unrelated
to the cluster, and lying some distance behind it.
M46 and M47 are fairly easy to locate off Alpha Monocerotis,
some 5 degrees to the north. However, this star is quite
hard to see in the city, being only mag 3.9, and very far
from any other visible star. If you cannot find alpha Mon,
you are faced with a very long hop from Sirius.
M93 is a bright, highly condensed, and attractive cluster.
Unfortunately for northern observers, it is fairly far south
of the Celestial Equator, making it a little hard to see
under heavy light pollution. Even so, it is visible at
latitude 42N in my 7x35 binoculars as a small but well-defined
patch of light, quite easy to see in the suburbs and fairly
difficult in the city.
In my 70mm scope at 60X in the city, I see two bright mag 8
stars, an obvious mag 9 star, six faint stars, and another
six or so with averted vision, all in a 15' circle. The
view is similar in the suburbs except there is also a hazy
background shimmering with stars that appear fleetingly as
I scan with averted vision.
In the 178mm scope, the cluster is framed best at around 60X
but shows more detail at higher powers. Some two dozen
fairly bright stars form the outline of a reverse P or
ampersand (see upside-down in my Newtonian), and under
suburban skies, I count another two dozen faint stars
within a 20' circle, although these fainter stars do not
contribute much to the appearance of the cluster.
M93 is very easy to find off Xi Puppis (mag 3.3), which
I can see fairly easily both in the suburbs and the city,
despite its low altitude. Xi forms a fine pair with
Rho Puppis (mag 2.7) 4 degrees to the east. If you
cannot see Xi or Rho, you can always star-hop from
brilliant delta CMa.
M48 is a large, bright, and interesting cluster which shows
well in large and small scopes and resists light pollution
well at medium to high magnifications.
Under dark skies, M48 is prominent in small binoculars
and faintly visible to the naked eye. From the city and
suburbs, it is vague and ill-defined in my 7x35 binoculars,
which resolve only a few bright stars, not enough to add
up to a cluster. The remaining stars form a haze with
very modest surface brightness which is easily masked by
M48 shows best at 40X - 60X in my 70mm scope, with the lower
powers framing the cluster better and the higher powers showing
more stars. I see about 15 stars in the city and about 25 in
the suburbs. My 178mm scope shows 40 or 50 stars, much the
same in the city and the suburbs. Again, 40X frames the cluster
best, but higher powers resolve the cluster better, especially
near the center.
The stars of M48 fall easily into patterns, but the patterns
are fluid and elusive. Sometimes I see 3 or 4 bright stars
near the north edge and a line of fainter stars oriented
east-west near the center of the cluster, forked into a
horizontal Y at the west end. Other times, I see all of
the stars forming an equilateral triangle 30 minutes on a
side, with that center line transforming into three spokes
linking the center to the sides. Regardless, the cluster
hangs together well despite its large size and the wide
range of brightness of its stars.
M48 can be rather hard to locate. I like to start from
the line of stars 1, 2, and c Hydrae, a lovely asterism
in binoculars and small telescopes, and to the naked eye
under dark skies. C Hydrae, at mag 3.9, should be visible
to the naked eye under most skies; it is fairly easy to
locate off the head of Hydra. If that fails, you will
have to do the heroic 14-degree star-hop from Procyon.
M44 is one of the few deep-sky objects that unquestionably
shows better in binoculars and small telescopes than in
large telescopes. It also is hurt very little by light
pollution, although light pollution makes it much harder
to find. Under dark skies, M44 is readily visible to
the naked eye as a fairly large patch of fuzzy light,
and I also find it fairly easy under decent suburban
skies, and visible with considerable effort from the
city. However, it is in an extraordinarily blank part
of the sky; no star within 15 degrees is truly
prominent under heavy light pollution. Delta Cancri is
very close, but at mag 3.9, it is barely easier to see
than M44 itself. If you cannot see either, you are faced
with a very long star-hop beta Cancri (mag 3.9) 12 degrees
to the SW, or from Zeta and Xi Hydrae (mag 3.1 and 3.4)
13 degrees to the S, possibly via M67, or if all else
fails, from dazzling Pollux 15 degrees to the NW.
M44 is enormous, as big as the Pleiades, and because of
its rambling shape, it requires a very large field of
view to frame it well, preferably at least three degrees.
This object is a perfect match for my 70mm scope at 16X,
which allows me to resolve at least 30 stars in the city.
I can see more stars using the same scope in the suburbs,
but they do little to improve the appearance of the
cluster. Even my 7x35 binoculars resolve some dozen
stars in the city and two dozen in the suburbs, yielding
a very attractive view of the cluster.
Although the stars of M44 are quite sparse, they form into
attractive geometric patterns, and the cluster contains
numerous double and triple stars. Most of the brightest
stars show strikingly red or yellow through my 178mm
scope, reflecting the fact that this is a fairly old
cluster. In my 178mm scope, the cluster looks best in
the widest field the scope can deliver, 2.4 degrees at
28X using a wide-field eyepiece. Higher powers merely
make the cluster look coarse and vulgar.
M67 is one of the oldest open clusters known, probably
between 4 and 5 billion years old, about as old as our
own solar system. Normally, open clusters are fairly
short-lived in cosmic terms. In fact, most astronomers
believe that all stars originated in clusters, but most
of the stars that we see today are free-floating, and
most of the clusters that we see are much younger than
an average star like our own Sun.
The ephemeral character of open clusters is due to
the fact that stars continually evaporate from the
surface, or are torn off by the tidal force of the
galactic disk. M67 survives because it is unusually
rich and dense, so that gravity binds it more tightly
than most, and because it is far from the plane of
the Milky Way, which minimizes the tidal force.
Most open cluster lie near or within the Milky Way
as seen from here on Earth, but M44 and M67 are
about 30 degrees away from the galactic plane.
However, the reasons are quite different for the
two clusters. M44 appears far from the Milky Way
because of perspective; we are very close to M44,
so its relatively modest absolute distance from
the Milky Way seems large to our eyes. M67 is at
least four times more distant, so the actual
distance from the plane of the Milky Way is at
least four times greater.
Although M67 is very rich, all of its stars are fairly
faint, which causes it to show poorly in small instruments
under bright skies. From the city, it is just barely
visible with averted vision through my 7x35 binoculars,
and it is also very difficult in my 70mm scope at low
powers. It does better in the 70mm scope at 60X,
showing 5 faint stars with direct vision and another
10 or so with averted vision. The cluster is far more
impressive from the city in my 178mm scope at 120X,
showing some 30 stars, and promising more with averted
vision. The brightest stars are arranged in an arrowhead
pointing E. Not surprisingly, they are all red giants,
although none is bright enough for the color to be
apparent in either of my telescopes.
M67 shows much better from the suburbs, where its faint
stars merge into a nebulosity that stands out well in my
7x35 binoculars, and provides a lovely backdrop to the
view in my 70mm scope. The 178mm scope at 120X resolves
about 60 stars in a 20' circle, a very impressive view.
In good suburban skies, M67 is very easy to locate off
alpha Cancri two degrees directly to the east. In all
but the worst urban skies, it can be located off the
head of Hydra six degrees to the south. Alternatively,
you can star-hop from M44, if you happen to be there