Last night after 11 PM I went out back to my 10" f/5.7 scope and poked
around Aquila for double stars. The moon was already past 1st Q and
bright, low in the west. The limiting magnitude was probably around 4, at
best - the sky looked silvery rather than black. Conditions were about 7
out of 10 for steadiness - there was some scintillation making the stars a
bit fuzzed out - squirmy - rarely did I see real pinpoints on the brighter
targets, but of course the dim field stars all looked good. I spent about
an hour, part of which was sipping a warm beverage - all in all it was a
very pleasant experience.
I began with Zeta, a type AO star 83 light years distant at mag 2.99, with
a 5 arc second split to its 12th magnitude companion. No dice. The 10 was
not going to hit mag 12 in these conditions so close to a bright star. I
looked for quite a while, occasionally thought I saw something north of the
field's lucida. I think this would be a fun target on a better night.
Next was pi, type F2 and 570 light years away. This was an easy target
being very close to Altair and Tarazed. This is a close double, with a
separation of only 1.4 arc seconds. It showed some elongation but would
not split cleanly. The pair are listed (in the reference I was using - The
Seasonal Star Chart) at mag 6.0 and 6.8.
On to 5 Aquilae, type A2 and 259 light year. The pair are mags 5.9 and 7.4
and an easy wide split at 13 arc seconds. I hopped to this target off
Lamda Aquilae - my 9x50 finder making it easy. The color was quite nice,
the primary being solid white and the dimmer companion a washed out blue -
a tinge. A visually pleasing pair.
11 Aquilae is a mag 5.7 and 9.2 pair, type F8 primary, 155 light years
distant. Located conveniently just off Zeta and Epsilon, there is a
noticeable color difference between the components, with the dimmer member
seeming to be even dimmer than the 3.5 magnitude difference. Easy split at
17 arc seconds.
15 Aquilae was, to me, the prettiest of the night's doubles. At the
southern tip of the constellation, just off Lambda, it is easy to
locate. The primary is a type K1, red, at mag 5.4 and 324 light
years. Visually, the primary appeared yellow gold, the latter showing the
red nature of the star. The companion though, described in the reference
as "lilac" ... to me appeared coppery yellow, and was noticeably dimmer at
mag 7.2 with a wide 38 arc minute separation.
After 15 Aquilae, I went on to observe 57 Aquilae, Struve 2446 and Struve
2628. They were fun too, but did not compare 15 Aquilae. It was getting
late, and my cup was empty. I was done.
The scope is still out back, where I will continue in a different
constellation tonight, with a bigger moon.
Maybe I'll even look at the ..... moon?
Mark
Received on Tue Jul 27 11:03:48 2004