Tales from the Land of Open Clusters
Saturday, January 10, I once again ventured to Henry Coe State
Park for a night of astronomy. I posted my intent on our local astronomy
mailing list and managed to tempt four others to join me. Surya and his son
(sorry, I forgot your name!) Vignesh, and Daniel. The preceding month, a
mountain lion was observed at the edge of the observing area in the early
morning. I wasn’t too worried about an encounter, but I was also glad to have
some company. Vignesh arrived a bit after dark and reported that the mountain
lion ran across the road in front of his car about fifteen minutes down the
hill! Luckily, we had no other sightings that night.
I brought a new-to-me Orion 120ST refractor on an AVX mount, as
well as an 8” Orion dob. I’ve been bringing a dob lately and an 80mm refractor
for when I want a wide field view as I continue to I work my way though Sue
French’s “Celestial Sampler” book. In the end, I mostly used the refractor, and
just used the dob for quick comparison views. Interestingly, I found the
contrast in the 120ST and the dob very close, although there were more stars
visible in the 8” dob. I really noticed this when observing M35. There is a
smaller, fainter, open cluster, NGC 2152, in a wide-field view with M35, and
though I could see more stars in the dob, I would say 2152 stood out just as
well in the refractor, and its slightly yellowish tinge was also apparent in
both scopes.
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The sunset was beautiful, with a deep orange color on the
horizon. There were high,wispy clouds late in the afternoon, but they seemed to
have disappeared by the time I was ready to begin my observing session. The
predicted low was 39 degrees, so I made sure I was layered up before I got
cold. The evening began cool without a breeze. That was going to change later.
I started my observing session with the essay ‘Fireflies.’ The
sole interest of this article is the Pleiades (M45). This open star cluster fit
perfectly in the field of view of the 120ST and a 24mm Panoptic. This
combination gave me 25x and a 2.7 degree field. I’ve observed M45 dozens of
times in a variety of telescopes, and just enjoyed the view of this beautiful
cluster without learning much about its members. I do usually look for the
nebulosity around Merope (NGC 1435) and Maia (NGC 1432). Tonight didn’t
disappoint, and the nebulosity was there, but it was subtle, and stood out a
tad better in the 8” dob, but points to the refractor for contrast! Sue also
featured a few double stars, ADS 2755, SAO 76206, and Struve 450. These were
all easy splits, and I didn’t
take any notes regarding colors.
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I went back to a couple of December essays, both in Cassiopeia. ‘Cassiopeia’s Chair,’ page 150, featured some of the
many open clusters that can be found in this prominent constellation. I must
admit, most of these clusters were not standouts visually, but they were still
interesting to observe, and two were showpieces. King 14 is a mag 8.5 cluster
situated in the same eyepiece field as Kappa Cass. NGC 146, mag 9.1, and NGC
133, mag 9.4, are also in the same view and all three are very close together.
All the members of this cluster are dim and to me were close scattering of
stars. NGC 133 was a bit more conspicuous as its stars made a ‘Y’
shape. NGC 255 was next and I saw perhaps 30 stars scattered about the field,
along with a few curved strands of stars. This cluster was discovered in 1784
by Caroline Herschel in a 4.2”
Newtonian. NGC 129 is a large, loose, cluster. Three brighter stars make a
triangle and mark the edges of the cluster. One of these brighter stars is a Cepheid
variable, DL Cassiopeia, at the northwestern point. NGC 7790 and NGC 7788 are
in the same eyepiece view and make a poor man’s
double cluster. 7790 showed eight members of equal brightness surrounded by dimmer
stars. 7790 is smaller and dimmer at mag 9.4. I observed four dim stars in a
small patch with a glow of fainter stars. NGC 381 was the last cluster in this
article and I found it to be quite interesting. There are five stars which make
a pentagon shape with one brighter star on one end, and then a string of stars
stretch out to make the whole cluster appear as a kite on a string.
The last essay of the night ‘File
Under W,’ page 152, was
again filled with open clusters, a double star and a diffuse nebula. Eta Cass
is a showpiece double star near Alpha Cassiopeia. They looked gold and blue to
me this night, though at other times I’ve
seen yellow and orange. I wonder what other observers see.
I’ve
always referred to NGC 281 as the Pacman nebula as it has the shape of that
hungry little guy. The view this night was subtle and improved a bit with an
OII filter. IC 1590 is the open cluster associated with NGC 281, and the
multiple star, Burnham 1, is the brightest star in that cluster. With the 120ST
and a 7 Nagler I was just able to split it into three members. I didn’t take note of any colors. As I
started to hunt down the next object, NGC 457, the wind suddenly picked up and
was gusty for the rest of my observing session. The 8” dob was practically useless as
the wind was shaking the tube and it was hard to get a steady view. Luckily the
refractor was on a sturdy mount and I was able to continue observing. Another
point for a little refractor! NGC 457 aka ET or the owl cluster was fantastic.
The two bright stars marking the eyes are the brightest stars in the field, and
chains of stars make a very recognizable pattern. NGC 436 is a small nubbins of
a cluster in the same field as 457. Stock 4 was a loose collection with no
patterns to my eye, but Sue thought it a pretty cluster. The last object was
NGC 744, another small bit of faint stars with a glow provided by dimmer
members.
At this point I decided to ruin my night vision and take a peek
at Jupiter. Not the best night for planetary viewing, but it’s always nice to spend a little
time with Jupiter and its moons. I started packing up and was on the road by
10:30 after four hours of observing. Two owls flew across the road as I made my
way down the hill, but no mountain lions. Maybe next time.
