(IAAC) FWD: Deep Sky on an Eclipse Cruise
[Individual logs will follow on 'netastrocatalog' shortly. -Lew]
Deep Sky objects observed while on an Eclipse Cruise
by Steve Coe
All the following objects where observed from the deck of the
S.S. Dawn Princess while cruising in the Caribbean Sea. I used
a variety of sizes of binoculars. In general the seeing was
5/10, not too twinkly, but not excellent, and the transparency
was 4/10, lots of humidity in the that part of the world. The
Saguaro Astronomy Club members found a location on the ship
that was forward of the bridge, it was kept dark so that
the bridge crew could see forward of the ship while steaming
to the next day's port of call. Certainly a unique viewing
experience to be observing from a gently rolling deck while
a 20 knot "breeze" is blowing. A moment's thoughlessness and
your star chart would be suddenly 200 yards astern. But I
have not had too many chances to observe the southern skies,
so I did the best I could with this opportunity. It is also
unusual to be able to observe for several hours and make your
way down a passageway to a place where a gourmet meal is
being served. It is unique to take a break from observing
and be served Beef Wellington and Cherries Jubilee. All in
all the eclipse cruise of Feb. '98 was a joyous vacation.
The Southern Milky Way is easily seen as a sweeping
glow that starts in Gemini, then through Orion, Canis
Major, Puppis, weakens in Vela, then bright and wide
again in Carina and Crux. Some dark lane structure
can be glimpsed, it is not obvious.
The Large Magellanic Cloud is somewhat difficult with just
the naked eye from this latitude. First, it is not above
the horizon much. Second, the humidity and clouds near
the horizon lower the contrast and make it difficult. In
the 10X50 binocs I could just see the Tarantula Nebula
and a faint glow of the main body of the galaxy. It was
much better in the 16X80s, the Tarantula is much easier
and the contrast between the galaxy and the sky is better.
Never a good view, but it was there.
The False Cross is an asterism of stars at the Vela-Carina
border that mimics the "Real" cross--Crux. The four star
of the False Cross form a somewhat larger cross than Crux,
but they do "tilt" at the same angle. Essentially, the
False Cross and Crux are on either side, east and west,
of the Eta Carina Nebula.
IC 2391 is on the west side of the False Cross. Naked
eye visible as a dim patch with two stars involved. With
the 10X50 binoculars there are 8 stars of mags 6..9 in
a loose grouping that reminds me of M-38 somewhat.
NGC 2516 is below the False Cross. It is easily resolved
in the binoculars, I could see 10 stars and a background of
unresolved members. It is somewhat triangular in shape,
brighter in the middle and compact. Beautiful line of
bright stars are to the north and west of this cluster.
It is easily naked eye.
Crux is an obvious naked eye asterism. The "top" star
is Gamma Crux and is seen as orange, even with no optical
aid. Comparing to Betelguese, it is about the same tint.
The other star with color in the area of Crux is Epsilon,
also known as Mariposa, Spanish for butterfly. Because
this star is dimmer than Gamma, I seen it as faintly
orange in the binocs, but not brilliantly colored.
Crux is always smaller than I have in my minds eye.
Eta Carina is unmistakebly naked eye, a bright, elongated
glow in the Milky Way. Using the 10X50 binocs it is a large
and bright nebulosity that is cut into two almost equal parts
by a V-shaped dark lane. There are 12 stars involved within
the nebula. With averted vision the outer, dimmer portions
of this huge nebula are seen. All together this nebulous
complex is about 2 degrees is size. Using a friends' 16X80
binoculars for a peek, I counted 16 stars involved and the
glow of the nebula is easily half of the field of view,
I estimate 2 degrees in size. The star Eta Carina is
yellow-orange in color, using the big binoculars.
IC 2602 is the southernmost of the three bright clusters that
surround Eta Carina. There are 12 stars resolved in two
groups. This cluster has a wide dark lane down the middle.
It is a sparse cluster, but the stars involved are bright,
I estimate 7th to 9th magnitude. I believe that it is only
because of its low altitude that I cannot see it naked eye.
NGC 3593 is above and to the "right" of Eta Carina. It is
very compact, but bright enough to be easily seen in the
10x50 binoculars. No stars are resolved.
NGC 3532 is a splendid cluster, I can resolve 32 stars across
the bright face of this large, dense open cluster. It shows
a high surface brightness and I can easily see it naked eye.
A hint of the dark lane that cuts into this group can be
seen on the north side of the cluster. Also, with the wide
angle view, I can see that NGC 3532 is in a very dense region
of the Milky Way. It is surrounded by a myriad of stars on
all sides, many in beautiful curving chains. Using 16X80
binocs, I could resolve 36 stars and the dark lane within
this cluster was much easier. Very much reminds me of M-11
and the Scutum Star Cloud.
NGC 3766 is between Eta Carina and Crux. It is obvious
in the 10X50s and has a high surface brightness. Only 3 stars
can be resolved with the binocs, but there are many other
bright stars just to the north of this compact cluster.
The 16X80 binoculars resolved 8 members and really frame up
the cluster with the bright stars to the north.
NGC 4755 is the Jewel Box. It can just be seen naked eye,
and 6 stars are resolved in the 10X50s. The stars are a little
different in tint, but not much in the binoculars.
The Coal Sack is discernable, but not easy. There is a
missing portion of the glow of the Milky Way in this region.
Alpha and Beta Centauri follow Crux over the horizon. They
are bright enough to be easy, even when only a few degrees above
the horizon. In the binoculars, they are twinkling nicely and
in a rich field of view. The stars of Centaurus and Lupus
are "above" Alpha and Beta. I cannot make a centaur out of
them, but there is a 10 degree square field with over 30 bright
stars, a nice naked eye view.
NGC 3114 is very nice in the big binoculars, I counted 28
stars resolved. Several nice bright stars are lined up in
curving chains that look to me like the fingers of a hand
or remind me of a spiral galaxy. There is a faint haze of
unresolved background stars.
NGC 3201 is an obvious globular cluster in the 10X50s, never
resolved into stars, but a very bright core and much larger
than the star images.