[AZ-Observing] NGC 2362 and NGC 2527
- From: BillFerris@xxxxxxx
- To: az-observing@xxxxxxxxxxxxx
- Date: Sun, 12 Jan 2003 20:46:49 EST
I drove down to Sentinel, Arizona, last weekend to observe with the folks in
the Saguaro Astronomy Club. The trip allowed me the opportunity to escape the
cold of winter in Flagstaff and--more importantly--the clouds. Although both
evenings suffered from high thin cirrus early, both also cleared nicely after
midnight. With my 10-inch Newtonian setup in the Kendrick Observing Tent, I
was able to observe and sketch 14 Herschel 400 objects for my website
(www.cosmic-voyage.net ).
I wasn't a big fan of open star clusters when I began the H400. But having
been treated to such gems as NGC 7789 and others, my dim view of OCs has
brightened considerably. However, my early bias is given away by the fact
that the 22 objects on my "to sketch" list entering last weekend were all
open star clusters.
The new sketches and observing notes have been uploaded to my website. But I
wanted to mention two clusters which really caught my eye: NGC 2362 and NGC
2527.
NGC 2362 (http://members.aol.com/billferris/n2362.html )
This is quite simply one of the most striking star clusters in the winter
sky. It is also among the most fascinating. Centered within the cluster,
although not necessarily a member, is 4.4 magnitude Tau Canis Majoris.
Hipparcos photometry revealed this wintry beacon to be not one but three
stars. A visual double consists of two O-type stars separated by 0.151
arcsecond. The brightest member of this binary system is, itself, a massive
binary with a period of just one day. Tau Canis Majoris is composed of the
longest period spectroscopic binary and the shortest period eclipsing binary
known.
My drawing presents NGC 2362 as viewed at 129X in my 10-inch Meade Starfinder
equatorial. A crisp white beacon of light at the eyepiece, Tau CaM is
surrounded by a host of fainter stars as shown in the sketch. Among these, is
a closely formed trio of faint stars immediately east of Tau. Seven arc
minutes due east, 6.8 magnitude PPM 252131 stands sentry at the edge of the
field. An equal distance to the west is 9.2 magnitude PPM 727417. In between,
lie more than 60 stars huddled around Tau Canis Majoris. NGC 2362 is 6' in
diameter, according to Archinal, so most of the stars in my sketch are
members.
NGC 2527 (http://members.aol.com/billferris/n2527.html )
People are good at finding recognizable patterns in nature. That's why there
are so many mountains, trees and even animals named after everyday things. We
do the same with deep-sky objects in astronomy. There are the Dumbbell
nebula, the Great Square of Pegasus, the Owl nebula and many other examples.
Let's add one more to the list. NGC 2527 features a striking half-heart
asterism. My drawing presents the view in the 10-inch, f/4.5 Starfinder at
129X and includes more than 70 stars across a 24' field.
If you take a closer look at the meandering string of 15 stars, which begins
at the center of the field with 9.6 magnitude PPM 253806, you'll discover
they form a familiar shape. The asterism winds southwest over a distance of
4' before gently curving south and east for another 4'. These stars form a
half-heart pattern within the star cluster. That's why I call NGC 2527 the
"Half-hearted Cluster."
NGC 2527 shines with an integrated visual magnitude of 6.5 and covers a 15'
diameter area, according to Lynga. Twenty-three member stars, in addition to
those making up the half-heart asterism, are shown in my drawing. The four
stars grouped near the south border in my sketch stand just outside the star
cluster. The brightest star in my drawing is 8.6 magnitude PPM 253817. It is
also just beyond the cluster's edge, 5'.5 northeast of PPM 253806. Your star
hop to NGC 2527 begins at 2.8 magnitude Rho (15) Puppis. Slew 4 degrees south
and a skosh west to find the cluster.
Both clusters are well-positioned for observation during the next new Moon
weekend. If you haven't already observed NGC 2362, it's a definite must on
your observing list.
Regards,
Bill Ferris
"Cosmic Voyage: The Online Resource for Amateur Astronomers"
URL: http://www.cosmic-voyage.net
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