Obs report, 25 Sep 2003: Some old warhorses and new nags

(I managed to get a full week behind in posting reports, so here
is the shorter one of the two. Enjoy.)

Date: 25 September 2003 (UT)
Time: 3:00-4:30 UT (9:00-10:30pm MDT)
Location: just west of Boulder, Colorado
Elevation: 7300 feet
Telescope: Criterion 6" f/8 Newtonian on a GEM
Eyepieces: 20/15/9/6mm Orion Expanse (61/81/135/203x), 7mm Ortho (174x)
Objects: M2, M71, M72, M73, NGC 6793, NGC 6800, Uranus, Neptune

We had another in a series of significant, but dry cold fronts
overnight. Unfortunately, that led to some haze, perhaps from
dust. During the day, I figured that this was not going to be
the kind of haze that signals good seeing. But, I was planning
on going out anyway, to the same site as two nights before.

I still haven't observed all the Messier objects with the 6",
so most of my plan was to pick up a few of those, as well as
Uranus and Neptune. I had seen Uranus with this scope before,
but in horrible seeing, and several times in the past with
smaller instruments including the unaided eye. Oddly enough,
I'm not sure if I had *ever* seen Neptune before; it never
seemed appealing for a 60mm refractor just because of the small
size. I located a few asteroids of similar brightness, so I
wonder if I did get Neptune and just didn't keep good records
back in the late 80s.

Seeing was unusually poor. I mentioned zeta Aqr in my last
report; it turns out that the current separation is more like
2.0" than 1.9". In any case, even near the end of the session
when it was about 45 degrees in altitude, I could not
continuously hold a split. The two pairs of eps Lyr were split,
but a little messy. So, I'll call it right at 2.0".

Uranus was pretty easy to find, and did look pale blue and
non-stellar at 3.4" across. Neptune wasn't too hard to find,
either, but at 2.1" across, I could not confirm that it was
non-stellar. There was a blue tinge and the starfield was
pretty much unambiguous.

The limiting magnitude wasn't all that great either; about 5.6
at Polaris, perhaps slightly better in the west 1/3, and much
worse in the east 1/3. This site is just a bit too close to
Boulder to be really good, but that's still dark enough to be
useful.

M72 wasn't very impressive. Maybe 2 arcminutes across and
rather faint. There was some mottling and hints of resolved
stars at both 174x and 203x. Just next door is the infamous
M73, perhaps the 2nd worst Messier object after M40. At least
M73 is a cute 4-star asterism. The 4 stars were easy to see at
81x. Right after this, the second car of the night showed up in
the parking lot. Traffic along the road was quite heavy, too.
I was probably just lucky two nights ago in that respect.

And then came M2, which was quite nice. It was a bright and
interesting object even at 61x. It showed hints of resolution
at 135x with at least a dozen stars resolved at 203x (yeah, a
little too much with 2" seeing; I'm already addicted to the 65
degree FOV of the Expanses vs. the 40 degrees of my Orthos).
There were hints of quite a few more resolved stars. It seemed
like a classic concentrated cluster. Definitely one to check
again under better conditions.

According to my master list of observed DSOs (which includes M40
and M73, but not other double stars or asterisms), M2 was my
41st DSO, first observed with 7x50 binoculars on 2 August 1986.
I bring that up, because after yesterday my list contained 599
objects. There is some fuzziness about what constitues an
"object" for this list. I include the Hyades and Alpha Persei
clusters, but not the "Coathanger" because it is not a real
cluster. I don't count the Milky Way as a DSO, although one can
make a good case for it. I also don't count large dust clouds
like the Great Rift in Cygnus for similar reasons. I saw two
members of Stephan's Quintet merged into one faint object, so I
haven't listed either one in the list. I still haven't sluethed
out some of my early observations so the object numbering may
change.

Given all of that, the first new DSO on the night would be
number 600 on the current incarnation of The List. Perhaps
fittingly, it was a mediocre open cluster from the Herschel II
list, NGC 6800. I saw a loose group of about 20 moderately
bright stars about 15 arcminutes across, with a few fainter
stars mixed in. There are some brighter stars nearby, but
perhaps not associated with the cluster. This part of the sky
is so rich in faint stars that it's hard to pick out the cluster
on the Digitized Sky Survey images! Other information suggests
that the true cluster is smaller than what I noted; usually I
end up underestimating the sizes of clusters.

I did another one, NGC 6793. This was a very poor gathering of
about 15 stars of varying brightness, spread across 8 arcminutes
or so. Again, it lies within a rich field in Vulpecula
neither cluster was very foxy.

While in the general neighborhood, I shot southward into Sagitta
for M71. Originally thought to be an open cluster, it is
actually a globular. It is certainly not a typical globular in
appearance. Even at 81x, there was a resolved group of stars
just off the east edge of the core area. By the time I reached
203x, I could resolve an additional dozen stars or so on the
face, which was rather loose and diffuse.

Brian Rachford