Following on the discussion about the visibility of Pluto in small
apertures, I had another try for it tonight (June 3 UT) with my 70mm Pronto at
Anderson Mesa. As some of you know, I looked for it a couple springs ago and
convinced myself I _probably_ saw it in several glimpses over the course of
about 20 minutes quite concentrated observation---very difficult.
Tonight Bill Ferris was at the Mesa with a number of visitors, and
mentioned that he had a large-scale chart from MegaStar showing GSC stars plus
Pluto on several adjacent nights. I borrowed the chart and worked on the
field for about half an hour. Luckily, even though Pluto is getting farther
south and encroaching on the Milky Way, it is presently going through some
regions obscured by dark clouds, making detection rather easy since there are
few background stars of similar brightness needing to be sorted out. (This is
not so problematic in larger telescopes of course.)
Anyway, I got several reliable detections at 95x in the Pronto, and
overall this series was much more convincing the the first shot a couple of
years ago. It was helpful that Pluto lay near a faint asterism, which it will
be near for another couple days. The field itself is simple to find about a
degree west of the naked eye star 20 Ophiuchi. The JPL 'Horizons' ephemeris
page (which cannot be more inconveniently designed---unbelieveable!) shows
Pluto with a predicted V magnitude of 13.75 presently, but since the variation
due to rotation is 0.2-0.3 mag., calling it roughly 13.7 or 13.8 is more
reasonable.

\Brian