Stardate:04:05:98
A Black Eye, a Sombrero, a Ghost, and
a Christmas Tree
The skies this week offer four interesting objects in the sky, each
with a descriptive name. These are the Black Eye galaxy, the Sombrero galaxy,
the Ghost of Jupiter, and the Christmas Tree nebula. All visible to the
south, they spread from the south east, to the southwestern skies. All
positions listed this week are as seen at 8 p.m.
The first object we will view is the so called Black Eye Galaxy.
You can find this in the east south east, about 40 degrees above the horizon.
The Black eye galaxy is also known as M104, or NGC 4594. This is a elongated
galaxy, and it seems to fill up about 9 minutes from side to side, or about
1/6 of a degree. Since backyard telescopes typically have a field of view
of about one degree, you can expect that the Black Eye galaxy will fill
about 1/6 of the field of view at medium power. Only a small image will
be seen through a pair of binoculars, which often have a field of view
of about 6 or 7 degrees.
The Black Eye galaxy has a magnitude of 8.5, which is about 25
times too dim to see with the naked eye. It can, however, easily be seen
with a small back yard telescope, or a pair of binoculars. For best results,
when viewing galaxies such as this, it is best to use very low magnification.
To do this, use an eyepiece with a very long focal length, such as 40mm.
This will make it easier to find the object you are trying to find, and
will also form a brighter image than an eyepiece with a shorter focal length
would offer.
On our way to our next target, the Sombrero Galaxy, we will take
a short detour to a trio of round galaxies, M87, M60, and M49. These three
galaxies form a triangle about 10 degrees away from the Black Eye galaxy,
down towards the southern horizon. They are dim and small, but they are
well worth the detour. Next, head to just slightly east of south east,
and about 19 degrees above the horizon. Here is the Sombrero galaxy, also
known as M104, or NGC 4594. This is an edge on galaxy, and so will appear
as a cigar shape. As seen from Earth, it appears about as large and bright
as the Black Eye galaxy.
Our next target of the night is known as the Ghost of Jupiter.
This is a planetary nebula with a central star, and is also known as NGC
3242. Interestingly enough, planetary nebulas such as this are formed when
stars shrink and cast off their exterior layers, most often when changing
from a red giant in to a white drawf. Our Sun will form a planetary nebula
in about 5 billion years, after destroying Mercury, Venus, and the Earth.
They are pretty, though. The most famous of
these is the Ring nebula. The Ghost of Jupiter is around 20 minutes in
diameter, or 1/3 of a degree across. At magnitude 9, it is about 60 percent
as bright as the Black Eye galaxy and the Sombrero galaxy. It can be found
about 15 degrees east of due south, and 26 1/2 degrees above the horizon
at 8 p.m all this week.
The last object of the night is the Christmas Tree nebula. A bright
open cluster, it can be found 42 degrees above the horizon just west of
southwest. The brightest and largest of this weeks objects, at magnitude
3.9, it is visible to the naked eye under dark country skies. Measuring
one degree across, it will fill a telescope's field of view at medium power,
and makes a lovely object to view with binoculars.