SAA OBSERVING: A Cloudy Evening at QUO

Hello, everyone. Here's a rough and ready account of my observing
session on this rather cloudy evening at Quadrivium Urban
Observatory -- or QUO for short.

At around 1930, as I was getting started, it was still civil
twilight: my idea was to let my eyes dark-adapt as the twilight
deepened. The sky seemed about 70-80% cloudy, maybe viewing
things a bit optimistically: but there was a clear area near the
western horizon, and maybe that would helpfully move closer to
the local meridian.

The cloudy skies added to the utility and delight of a tool
associated with the illustrious John Flamsteed, England's first
Astronomer Royal: sidereal time. I placed the expected sidereal
time at midnight around 1034: a check of my calendar, after the
fact, shows that it will actually be very close to this. Now for
the fun: seeing how long it would take to get dark, and trying to
visualize where some likely DSO's would be if happy breaks in the
clouds occurred at the right place and the right time.

While it wasn't the best of observing nights, it did feel like a
good night to get some practice for two coming QUO events: a
Hodierna Southern Marathon sometime around March 21-29 or so; and
a series of sessions to observe the International Year of
Astronomy 2009 program known as _100 Hours of Astronomy_ to be
held on April 2-5.

As the twilight gently deepened from civil through nautical to
the verge of astronomical, I reflected on the somehow less than
heroic nature of simply pulling back the drapes, pulling up the
Venetian blinds, and reclining on a mattress in my observatory
with my _perspicilla geminata_, or "twin telescopes" of 7 cm
aperture -- in other words, 15x70 binoculars.

"Ah," I mused, "isn't this rather a contrast to the adventures of
Uncle Rod, who has been known to drive a vehicle into a
thunderstorm in hopes of testing a new catadioptric telescope if
it happens to clear?" California, I was well aware, was famed for
its "decadence" -- something proudly proclaimed on the containers
for some of my favorite flavors of soy ice cream -- but must I
serve as the prime exhibit to bear out this reputation?

That point aside, I focused on the welcome advancing darkness,
and spotted Sirius through the prevailing "nebulosity" of the
terrestrial rather than celestial variety. Apart from being a
token that it wasn't _totally_ overcast, that second brightest
star in the sky served as a helpful marker of RA: M41, at
something like 06h46m, would be a bit below.

At around 2005, I logged my first DSO's: M42, and nearby open
clusters NGC 1981, 1977, and 1980 (moving from north to south).
Curiously, I associated the NGC numbers with former President
Jimmy Carter: 1981 and 1977 were the years that he left and
assumed office; while 1976 (the NGC number for M42 itself) and
1980 were the years of the elections he won and failed to win.
Despite the prevailing cloudiness, the delightful interstellar
"fog" of M42 came through. Might one say that as the nebulosity
of M42 marks a nursery for stars, so a "not-quite-overcast" night
can serve as a nursery for observational inventiveness?

At 2008 I excitedly looked Cr 140, the "Southern Bear" which as a
binocular asterism includes Cr 140 proper in the tail of Canis
Major plus three bright stars in neighboring Puppis. Given the
clouds, I wasn't surprised in this less than perfect transparency
not to be able to "kiss the Bear's nose" by seeing the rather
faint "nose star" distinguishing this Bear from a simpler
Southern Dipper.

At 2009, I confirmed that adage that if Cr 140 shows up, can
Cr 135 be far behind -- or actually a bit ahead, since it is a
bit to the west with an RA of around 07h17m. I call it a kind of
"cosmic sail."

As another saying goes, "RA is nature's way of telling you what's
next on Dec." The reasonably clear view of Cr 135 suggested to me
that NGC 2451 just might appear on the scene shortly, as the
Earth persisted in rotating through 360 degrees every 86164.09053
seconds, more or less.

At 2012, I made a relatively northern excursion and found the
"pointer asterism" just to the east of M41 -- but not, in this
sky, M41 itself, a rather bright "faint fuzzy" and yet hard
comparable with a bright star. Likely I would have to leave this,
as well as the yet more subtle and at least equally captivating
M93, for a clearer night.

At 2018, the young night gave me an opportunity to reflect on a
question of "ground rules," as I spotted the "semicirclet" of
Canis Major and the nearby Tau Canis Majoris, which I knew marked
the location of open cluster NGC 2362, of which this bright star
is quite possibly itself a member. In light-polluted skies like
mine, should finding Tau Canis Majoris count as an observation of
NGC 2362 -- or maybe "half an observation," like arriving at a
stalemate in chess (whether the half-point for a draw under the
French and Italian rules of the 16th century which on this point
prevail today, or possibly the "half-win" under the Spanish rules
of that time)?

Anyway, at 2037, I had a less ambiguous moment of joy: there was
NGC 2451 in beautiful clarity about 15 degrees above the horizon,
along with the "J-shaped" asterism (including d1-d2-d3 Puppis)
just to the west of it! I could hardly ask for better on a nice
clear night, and this was another lesson on the rich rewards of
horizon hugging.

At 2051, I looked at this region again -- and there were NGC 2451
and the adjacent asterism in renewed clarity, although to the
north was cloudiness. From my catbird's seat, I moved southeast
from this open cluster through an asterism which struck me like a
kind of a celestial musical notation for two voices in
counterpoint converging on a unison (reading west to east) at
bright Zeta Puppis.

From there, right around 08h00m, I scanned down near the horizon
to the area of Cr 173, maybe the southernmost DSO I've observed
from QUO. I'm not sure if I could pick out Gamma Velorum, also
known as Regor, but I did see enough stars in that area to feel
that I had gotten some impression of Cr 173, a rather thin and
dispersed open cluster with a diameter of maybe 5 degrees. For
such an extended object, not even my 15x70's could quite cover
the whole area with their 4.3-degree field; but they did cover
much of the area.

At around 2110, I enjoyed a view of the "NY triangle" including
the Cepheid NY Velorum and two other bright stars to the south.
Especially through this cloudy sky, I was unlikely to have much
opportunity of going for the open cluster Tr 10, which light
pollution and a generous number of atmospheres may make less than
probable even with optimal transparency (at as long as some of
the neighborhood street and railroad lights are on and uncapped).

And so I decided to call it a session, and write it up for s.a.a.

To the above notes, I would just add one very strong impression
that hit me at the conclusion of the session: the beautiful
association of NGC 2451 and that "J-shaped" asterism next to it.
From the viewpoint of an observer like Giovanni Battista Hodierna
who marked an object in this area on his atlas map of Argo Navis,
either of these objects (as well as possibly some others) would
likely be a _nebulosa_ or "nebulosity" resolvable into stars. The
issue of whether such a visual _nebulosa_ is a "true DSO" bound
by gravitational forces, or a mere asterism, really belongs to a
later period. The sheer wonder remains after 350 years, spiced
with the discoveries of satellite missions which indicate that
NGC 2451 may actually represent _two_ juxtaposed physical
clusters at different distances sharing the same region of RA/Dec
from a terrestrial perspective.

With many thanks,

Margo Schulter
mschulter@xxxxxxxxxx
Quadrivium Urban Observatory (QUO)
Lat. 38.566-o Long. -121.430-o
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