[AZ-Observing] Observations

  • From: "AJ Crayon" <acrayon@xxxxxxx>
  • To: "SAC Forum" <sac-forum@xxxxxxxxxxxxx>, "AZ Observing" <AZ-Observing@xxxxxxxxxxxxx>
  • Date: Sat, 21 Mar 2009 10:06:42 -0700

Heading out to observed this weekend?  Then here's a list of objects to observe 
that will appear in the SAC newsletter - that is they will appear if you send 
your observations in for publishing.
Regardless of your observing list have a good time observing!

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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