Bruce McGlashan wrote:
--- In OAFs@y..., attilla.danko@s... wrote:
--- In OAFs@y..., "Bruce McGlashan" <mcglashanb2@h...> wrote:
As at Mike's, there was a
colour gradient across the disk, at about a 45 angle. In the NW,
it
appeared yellow-white, while in the SE, it appeared more orangish,
with a
tinge of turquoise-blue right at the edge of the disk. Could that
be
chromatic aberration?
Its much more likely to have been caused by the atmosphere
rather than your scope. All objects when observed at low altitudes
tend to show it, its just easiest to see on planets. The real
proof is to rotate your scope. Atmospheric chromatic dispersion
wont rotate. It will always show a color separation up and down.
On a polar aligned scope, that might look like a 45 degree angle
depending on how your star diagonal is aligned.
Thanks! I'll check this out next time.
Interesting piece of trivia. The colour caused by the atmosphere came
up a while ago on sci.astro.amateur (which I spend entirely too much
time reading - except for the authors and topics I've just kill-filed)
wrt some reviews of the Takahashi Sky 90. Basically the atmosphere is
just acting like a big prism. The neat thing that someone brought up is
that there is apparently an eyepiece that someone (British I think)
where one of the lenses can be moved around so that it acts like a prism
in the opposite direction. And there was some other widget where an
actual prism got introduced in the light path to again cancel the
atmospheric effects. Personally I would be skeptical as to the final
image quality you could get - or maybe I just misinterpreted what was
being described.
by 03:00 I was getting tired and cold.
An impressive observing seesion for a weeknight.
Maybe not. I'm on vacation this week.
Ah-hah! (that's cheating!!) Lucky you.
Actually, Saturday morning I got home from Mike's and after minimal
unpacking and walking the dog (short walk) I got up to the bedroom at 4
to find my wife reading a book. Apparently she woke up at 2 and I
wasn't home and then spent her time waiting for the call from the
police... she's now threatening to get me a cell phone for my
birthday. (She and I both consider cell phones to be inherently evil
:-) Anyone have any recommendations on phones/plans for very infrequent
use?
-ad
Bruce McGlashan
p.s. In case I don't talk to any of you beforehand, I hope the
weather
cooperates tonight and on Saturday. I'm off to Toronto tomorrow, for
my
brother's wedding Saturday, so I won't be participating in any
activities
until next week.
