Mark Wagner wrote:
> I also found that it was not too bad observing galaxies with a
> 5+ day old moon. ...
I have had that experience. In general, I find that to have much
chance of seeing galaxies, I have to use sufficient magnification to
make the sky background, seen through the eyepiece, look dark. That's
not all that is required, of course -- e.g., 1,000,000X in daylight
will probably darken the sky but I doubt it will bring in any galaxies.
There are diminishing returns, for me at least, with exit pupils much
below 1.5 mm. Yet a 1.5 mm exit pupil is enough to darken the sky
background well into the lunation, or alternatively under considerable
city lights, and make galaxy observation possible.
There is another problem with the Moon or with city lights that
rears its head at such times, though; namely, dark-adaptation. Doing
galaxy work with significant amounts of moonlight or city lights
is a good time to worry about keeping your observing eye closed,
or covered with a patch, when you are not using it, and perhaps to
observe with a dark cloth wrapped around your head and the part
of the telescope where the focuser lies.
-- da Weasel
Received on Thu Apr 14 13:03:11 2005