Hi, everyone. This is another quick and informal observing
report to keep up the signal-to-noise ratio, I hope, and also
to convey the sheer excitement of an experience which curiously
does seem to fit the title "Star Trek" -- a journey of some four
hours from Corvus to Sagittarius and M25 through the beautiful
southern skies.
Using 15X70 binoculars, I started a bit before midnight (PDT,
7 hours earlier than UT) in Corvus, starhopping north from
Delta Corvi to find the area of M104, although I'm not sure if
I've yet seen it through urban skyglow even with a 20cm f/6 Dob.
Then to the main item on my planned agenda: surveying some of
Centaurus.
While I didn't seem to observe any DSO's in that constellation,
I did get a look at Zeta Centauri at around -47-o declination.
That's about the limit of my unobstructed view, and some 4-o
above the theoretical horizon. As a bright point source, Zeta
Centauri was easily spotted through the shifting haze and fringes
of local light trespass; it remains an open question whether or
how well I would be able to see extended objects this low. Anyway,
getting down to 47-o wasn't a bad start.
For this I used a "catbird seat" -- basically a large pillow that
would elevate me and give me a view of lower altitudes through the
window of my live-in observatory, also known as my apartment. To
observe things at less "envelope-pushing" declinations, I can simply
sit or lean back with the binoculars.
The area around Zeta Centauri has a beautiful asterism, and I enjoyed
it for its own sake even while considering the combination of good
timing and a clear horizon that I would need to see NGC 5139, Omega
Centauri, which is the original motivation for this exercise.
Then moving on, at around 00:58 I spotted a delightful trapezoid in
the neighboring constellation of Lupus, which led me by 0110 to a
star I had noted in the _Millennium Star Atlas_ as Bidelman's Helium
Variable (around 14h24m and something like -39-o declination, as I
recall), also V761 Centauri if my information is correct. It turned
out that one of the stars of the Lupus trapezoid was around 149 light
years distant -- so that the light I was seeing would have left
around 1859, the year of John Brown's raid at Harper's Ferry in the
USA to free the slaves, and also of Darwin's _Origin of Species_.
At 0117, I spotted Alpha Lupi, like Zeta Centauri at around -47-o,
about the same as NGC 5139. Of course, again, I reflected from much
experience that being able to observe a bright point source does not
necessarily mean that extended objects, even bright ones, will be
equally visible under urban conditions <rueful grin>!
At 0213, as the Earth rotated and the stars thus appeared to progress
in a stately promenade, a familiar landmark appeared: the "Pentagon"
formed by Antares, Rho Ophiuchi, and some other stars in that region,
a pattern which might almost seem to serve as a shared "capital" of
two constellations, Ophiuchus and Scorpius. At that point the local
sidereal time (LST) was about 1534 (based on an LST at midnight PDT
of about 1321), and Antares is at about 16h29m. That tells me that
I was about to see Antares almost an hour before its transit of the
meridean, at an hour angle (HA) of about -0h55m, a useful guide for
the future.
At 0230, from the catbird seat, I saw a new favorite object: NGC 6231,
the "Scorpius Jewel Box" or "Northern Jewel Box" of the southern skies,
not to be confused with another "Jewel Box" looked further south in
Crux. This is located around 16h54m at -42-o, and is a bright open
cluster about 15' across which comes through well even in bright
urban skies at around 10-o above the horizon. While it isn't on
Messier's list from the simple reason it doesn't make it above the
horizon if one is observing from the region of Paris, Hodierna does
describe it in 1654, having had the benefit of a more southernly
Italian venue. This makes it a real gem of early DSO history, as
well as a sheer visual delight.
At 0246 I thought that I might have observed, moving back north to
the pentagon, M4. Was I seeing it, or simply visualizing it where
I wanted it to be, located below and not too far from midway between
Antares and another star forming the base of the asterism? On repeated
attempts with various uses of direct or averted vision, it seem at times
to be a distinct "smudge" of light -- could 70mm aperture plus binocular
vision achieve this under urban conditions when with the Dob I had not
discerned anything clearly. Then again, curiously, I had noted that M22
was about as easy to spot in these binoculars as it seemed in the Dob
the first time I saw it.
It also looked for M80, at wasn't sure if I saw it, but at any rate
learned about where to find it -- helpful for darker skies also.
At 0319, a moment of delight as I found the first Messier object I
had sought out and observed as such: M7, not quite a year ago! There
it was; if I view it from the catbird seat, it seems comparatively
a "northern" object by comparison to something like NGC 6231. At
not quite -35-o, M7 is the southernmost Messier, and a beautiful
open cluster it is. It's too low a declination to see with the Dob
from my observatory, but with the binoculars it's easy.
A few minutes later I looked again at the M4 region, and concluded
that the smudge I seemed to see "looked credible." Making a sketch
of an object definitely seen along with surrounding asterisms and
the like, and then determining what it is, is generally just a
matter and patience and access to the right resources; but deciding
if one has actually _seen_ something at a well-known location is
a different kind of puzzle. My guess is that I actually saw M4,
at least some of the time -- but that maybe the best thing would be
to practice my averted vision more, which might either confirm or
possibly tend to disprove my problematic "sighting."
At 0348 (around 1709 LST) I got another view of M7, and this time
also found and enjoyed M6. By 0358 I had also spotted M8 and M20
(or more precisely their prominent open clusters), as well as M24,
the Small Sagittarius Star Cloud. At around 0402, I concluded with
M25 (an open cluster very distinct and with lots of framing in a
4.3-o FOV) and M22, a globular cluster which comes through very
clearly.
What's hard to describe in words is the total experience: the
slow progression of the stars, and the alternation between
purposeful and sometimes even hurried searches for specific
DSO's or other objects of interest, and the more relaxed periods
of simply enjoying a pleasant asterism or even a randomly
selected starfield: "Thus engagingly crowded region may not
constitute a DSO, but it's no less agreeable to the eye."
Also, I find myself starting to learn about things like stellar
"associations" -- maybe enlarging a bit the usual concept of
a DSO.
Anyway, that's the story of a night at the time of year when
the summer approaches, with Scorpius and Sagittarius as its
welcome celestial harbingers.
Most appreciatively,
Margo Schulter
mschulter@calweb.com
Goes to show one doesn't have to catalogue all the globulars of the
