[AZ-Observing] Observing list
- From: "AJ Crayon" <acrayon@xxxxxxx>
- To: "SAC Forum" <sac-forum@xxxxxxxxxxxxx>, "AZ Observing" <AZ-Observing@xxxxxxxxxxxxx>
- Date: Thu, 23 Apr 2009 11:14:17 -0700
If you are going out to observe this weekend check the following for a
recommended observing list. It is the list of objects that will appear in an
upcoming SAC newsletter. But, if and only if, you observe them and send the
observations in to me in time for the article. So far Jack Jones is only one
to submit. We can do better, can't we??? ;))
Here's the list and if it looks familiar then you are to be congratulated for
reading the e-mail because it is same as last weeks.
Time for a second trip through Lynx and the star of galaxy season. The
selections will include a number of barred spirals and, if the galaxy appears
elongated it should be the bar. We start near 27 Lyncis to find the barred
spiral NGC2500, which has a bright nucleus in the bar. Moving to the southeast
is NGC2537, the Bear Paw or Bear Claw Galaxy with asymmetrical spiral arms.
Now going a little to the north is NGC2541 another barred spiral. The next
galaxy, NGC2683, is in the 110 Best NGC and Herschel 400 lists. Look for some
mottling on the northwest side. Continue the eastward trek to NGC2770
sometimes referenced as NGC2770A. It is a rather small late type spiral and
faintest on this list. Finally, the eastern most, is NGC2776 an almost face-on
barred spiral. The bar may not be easily seen yet the bright nucleus should be
easier to detect.
We will now begin a two month observing session to better understand the Hubble
sequence of galaxies. Unfortunately, because of space limitations, we will not
be able to cover them exhaustively, nor will we be able to discuss their many
nuances. Yet there will be enough to give the observer and idea how the
sequence relates to each other. The basic sequence starts off like a tuning
fork with ellipticals on the horizontal part; spirals such as Sa, Sb and Sc on
the upper part and barred spirals like SBa, SBb and SBc on the lower part. The
ellipticals are smooth featureless structures and are shaped anywhere from
round to elliptical, with some brightness changes towards the middle. Spirals
are flattened disk with stars forming arm-like structures from a brighter
central bulge. The barred spirals are like spirals but have a bar like
structure emanating from the central bulge. Its brightness normally falls
between central bulge and arms. Please keep in mind galaxies don't easily
follow these divisions nicely as some are difficult to categorize because they
could be assigned to more then one class, which leads to more classes and
subdivisions. Selection criteria for our galaxy study is based on orientation
and magnitudes that are within reach of SAC scopes. Ignore non-referenced
field galaxies.
So, with the above introduction here are the next two month's worth of
observations. For June we begin with the E1 M105 in Leo then E7 NGC3384 aka
NGC3371 in Leo both in same field of view but ignore NGC3373. For spirals
start with the Sa NGC4429 in Virgo then the Sb NGC2985 in Ursa Major and
finally the Sc M99 in Coma Berenices. For July begin with the E1 M84 and E3
M86 both in Leo and in same field of view next is E4 M49 in Virgo. For the
barred spirals begin with the SBa NGC3227 in Leo then SBb M95 in Leo and SBc
NGC4535 in Virgo. Now which do you prefer, elliptical, spiral or barred spiral
galaxies? Personally I prefer spiral or barred spirals.
There are a plethora of others, which also includes irregulars and dwarf along
with the many subdivisions. For more study see
http://en.wikipedia.org/wiki/Galaxy_morphological_classification that covers
lots more. See also Luginbuhl and Skiff, Observing Handbook and Catalog of
Deep-Sky Objects; Kepple and Sanner, The Night Sky Observer's Guide and
Steinicke and Jakeil Galaxies and How to Observe Them.
AJ Crayon
Phoenix, AZ
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