|
|
|
Constellation
Report
|
| Our Constellation
Report is an easy way for people to
become familiar with the nighttime sky. We’ll discuss myths associated
with a particular constellation as well as describing the numerous deep
sky objects residing within its boundaries. No equipment is required to view the
constellations, though a star chart can be quite helpful. This ease of
observing makes constellations a natural place to begin your journey to
the stars.
This weekend we move on to the constellation
Cassiopeia the Queen.
Cassiopeia was the wife of Cepheus the King and the mother of Andromeda. When Cassiopeia objected to the wedding of
her daughter to Perseus, Perseus displayed the head of Medusa, which he had concealed in his travel bag. As a result,
his enemies, including Cassiopeia, were turned into stone. Cassiopeia was
placed in the sky by Neptune.
As she sits on her W-shaped throne she circles round and round the pole.
Cassiopeia is what is known as a circumpolar constellation. This is one
which is visible no matter what the season or time of night. In the fall Cassiopeia is in
the shape of a W and in the Spring she is in the shape of a M.
|
 |
|
Deep
Sky Report
|
| The focus of our efforts this week will be the deep sky objects of
Cassiopeia. Cassiopeia is high overhead and to the north, northeast.
I always describe Cassiopeia as the Big W. This, and the fact that it is made up
of a bunch of fairly bright stars, should make it pretty easy to find.
Cassiopeia is north of Andromeda and west of Perseus -- constellations which we've looked at in
previous reports,
|
 Here's
a shot of Cassiopeia taken in August of 2003 by Anthony Arrigo of Utah
Skies. Click on the image if you'd like to see the lines
drawn... this should help you to identify things easier. |
 Check
out this incredible shot of Cassiopeia A... a one million second x-ray
exposure taken by the orbiting Chandra
X-Ray Observatory. |
 RGB color composite of nebula near the variable star LW Cassiopeia, made by
Al Kelly from filtered images taken by Arne Henden of the
US Naval Observatory in Flagstaff, AZ with the USNO 1.0- meter telescope. Arne made 6 images using UBVRIH filters. Al composited
U+B=blue, V=green, and R+I+H=red.
|
 Ok, let's start things off with
the first of two Messier objects in this weeks report. Open star cluster
M52(mag6.9). This is a beautiful object in binoculars and is absolutely
stunning in larger aperture telescopes. Discovered in 1774 by Charles
Messier,
M52 is a fine open cluster located in a very rich section of the Milky Way.
There are an estimated 200 actual members in this cluster.
The distance of this cluster is not very well known; estimates range from
3000 to 7000 light years. Amateurs can see M52 as a fuzzy patch in good binoculars or finder scopes. In 4-inch telescopes, it appears as a fine, rich compressed cluster of faint
stars, often described as of fan or "V" shape; the bright
yellow star is to the SW edge.
M52 can be found quite easily by extending the line from Alpha over Beta Cassiopeiae by 6 1/2
degrees to the NW to 5th mag 4
Cassiopeiae; M52 is roughly 1 degree south and slightly west of this star.
Situated about 35' SW of M52 is the Bubble Nebula NGC 7635, a diffuse nebula which appears as a large, faint and diffuse oval, about 3.5x3'
around the 7th-mag star HD 220057 of spectral type B2 IV. It is
difficult to see because of its low surface brightness. Just immediately south of M52 is the little
conspicuous open cluster Czernik 43 (Cz 43), which is visible in larger telescopes only.
|
 Next we'll hit
a sweet spot in Cassiopeia, NGC7635... more popularly known as The Bubble
Nebula. (mag10.0). There is a bit of misidentification regarding the
Bubble. The Bubble is a subset of NGC7635. It is the small arcing portion
of gas surrounding SAO20575... the bright star near the center of the
nebulosity. The Bubble spans 3' while the full extent of NGC7635 measures
15'x8'. The whole of the nebula should be visible in say 4-6" of
aperture... while The Bubble itself will probably require10" or more
under dark skies.
This gorgeous shot was taken by Utah
Skies subscriber Edward Lunt.
|
 Next we'll hit the other
Messier Object in Cassiopeia, Open Star Cluster M103(mag7.4) Discovered by
Messier's assistant Pierre Méchain in 1781, M103 is one of objects which Messier included from Méchain's report, but had not
actually observed himself prior to publication. This
loose cluster of some 60-70 members is one of the more remote open clusters in Messier's catalog, at about 8,000 light years
Its appearance is dominated by a non-member foreground star called Struve 131. This
beautiful double is made up of a mag 7.3 and a mag10.5 star separated by a
mere 13.8". The age of the cluster is estimated to be around 25 million years.
M103 contains one red giant star, obvious in color photos of the cluster; this star is of about
mag 10.8.
M103 is visible in binoculars as a fuzzy patch of light. It is not so easy to identify in telescopes because it is quite loose and poor, and may be confused with star groups or clusters in the vicinity. Situated nearby are a number of other open clusters, including Trumpler 1, NGC 654, NGC 659 and NGC 663. The latter is sometimes mentioned as a candidate to be
confused with M103.
|
Next up is another of Cassiopeia's very
beautiful Open Star Clusters, NGC457(mag6.4). Otherwise known as the Owl Cluster, this cluster is actually the brightest of Cassiopeia's open star
clusters. Displaying some 80+ member
stars to viewers using larger scopes(12+"), this cluster is a beauty
in any instrument. Astronomical binoculars will provide a very pleasing
view and 8" telescopes will reveal most of the 80 stars mentioned
above. This cluster is a bit brighter and has more members than M103. The distance to NGC457 is estimated to be
about 8000 light years.
Checkout the two bright stars at the bottom of the
cluster. These are thought to be foreground stars, not actual cluster
members.
To locate this object, use mag5 phi Cassiopeia as
your guide. This star should be visible to the naked eye under relatively
dark skies. It is located about 2° south/southwest of Delta Cassiopeia.
Utah Skies own Anthony Arrigo took the accompanying shot on
September 7th, 2003 using eyepiece projection to 15x through a 120mm f/5
refractor with a Sony DSC-F717 digital camera. This image is the result of
stacking three 30 second exposures.
|
Moving on, we come to yet another
beautiful Open Star Cluster NGC559(mag9.5). Located about 3° west of
Epsilon Cassiopeia or 3° north of Delta Cassiopeia, this little known cluster is
a hidden gem. The key to
identifying this little cluster is to be able to separate it from the incredible
density of stars in the area. To see this object, you'll need at least an
8" telescope. Otherwise, it's stars are too faint... and it's
background too dense. Even with this size telescope, you'll only see a
small portion of its stars. To truly appreciate NGC559, you'll want a
large telescope (16+") and dark skies. Part of the reason for this is
the fact that there is a considerable amount of intervening dust which
reduces the brightness of this object. In fact, it is dimmed by almost a
full magnitude because of this. Anyway...In the 25" under dark
Utah skies, this object is absolutely stunning. You can get lost in the endless star patterns contained within it.
|
 Up next is... yup.. you guessed it. A beautiful open star
cluster. Surprised :) This time it's NGC663(mag7.1)
Looking beautiful in a nice pair of binoculars, this beauty is absolutely
beautiful in telescopes starting around 6". It is at this size that
you'll start to resolve its individual member stars. Use low to medium
power to really enjoy this object as it's fairly large -- almost 1/2 the
diameter of the full moon.
To find this object, simply move about 1° east of the line between
Epsilon and Delta Cassiopeia. You'll quickly stumble over the star
clusters in this area. To identify this cluster, remember that NGC663 is
the largest in the area. NGC654 located slightly closer to the line is
brighter, but considerably smaller. Anyway.. while you're in the area,
cruise around and take in the beauty. This is an incredibly rich area,
so... take your time and enjoy!
|
Ok. So you're looking for a change of
pace... getting tired of all those beautiful open star clusters. How's
this for a change...Elliptical Galaxy NGC147(mag9.3)
This galaxy will be quite a bit harder to find than it's mag9.3 might
suggest. This is a large object with a very low amount of surface
brightness. In fact, were we not saving a real challenge for you.. this
could easily be a candidate for the Utah Skies Challenge. Anyway... since
this and NGC185 which follows are so close together, I figured that you'd
be able to find them fairly easily. This object appears pretty featureless
in the eyepiece -- pretty much an elongated smudge. The stars that you see
are actually foreground stars. There is a slight brightening towards the
core.
To find this, travel about 6° south of alpha
Cassiopeia.
|
Continuing about 1° to the east, we come
to another Elliptical Galaxy NGC185(mag9.2) . These galaxies
are so close to each other...and so close in brightness... that
finding one would essentially lead you right to the other. I'm hoping
that you've identified both of these. In case you're having difficulty,
NGC185 will appear the brighter and more concentrated of the two. In
any case, you'll need at least 8-10" and dark skies to simply view
these. If you want to see these objects and be impressed, you'll need to
try to gain access to the Hubble Space Telescope :) Both appear relatively
featureless, even in large instruments. I've seen both in the 25"
under dark skies.... and was not overly impressed. However...if you find
these in a small telescope... that would be quite impressive indeed :)
|
Moving back to Open Star Clusters we come to NGC7789(mag6.7). This
beautiful image was taken by former Utah
Skies Astrophotographer of the Month, Al
Kelly. |
 Let's wrap things up with this weeks Utah
Skies Challenge Object, a sweet Planetary Nebula IC289(mag12).
This
object is pretty small at only 36". But.. this will probably help you
due to a relatively high surface brightness. As you sweep the sky at low
powers searching for this object, it will appear almost stellar when you
come across it. With averted vision, you'll pickup the nebulosity. Once
you've found it, switch to high power. This object will take all you can
throw at it. Also, if you have some nebula filters, now's the time to try
them out. I've had best luck with my OIII filter.
IC189 is located about 10°
east/southeast of Epsilon Cassiopeia, the northeastern most star of the
"W", this object is in a pretty sparsely populated area of the
constellation.
This beautiful image was taken by a
former Utah
Skies Featured Astrophotographer, Michelle Stone. You remember her,
don't you? If you haven't been to her
website... I'd recommend doing so. It's full of beautiful images.
Good Luck!
|
|
|
Events |
| |
|
|
Did you ever consider... |
|
"Some scholars are like donkeys, they merely carry a lot of books." |
|
|
News |
| |
|
Newsfeed
Sun
Mercury
Venus
Earth
Moon
Mars
Jupiter
Saturn
Uranus
Neptune
Pluto
