On Oct 13, 2005, at 12:20 PM, Marek Cichanski wrote:
> For those of you going to Costa Rica, here's a neat thing to do when
> you look at Omega Cen: Put in an eyepiece that makes it fill most of
> the field, and then move your eye around so that your 'averted vision
> aim point' drifts all around the field. You'll see Omega Cen seem to
> morph and change shape. The brightest part of it will move around,
> like you were pushing a little slippery piece of jam around on a
> slippery plate. I eventually realized that Omega Cen is so big and so
> even in surface brightness that you can 'emphasize' one part of it or
> another by moving your 'aim point' around. It's kind of a funky
> effect, and I had never really noticed it on any other object.
For another interesting perspective on Omega Centauri, here's my last
observation in July from Australia. I'm not sure if this feature only
shows up clearly in larger scope, but it was pretty striking to me (and
apparently John Herschel!).
Steve
18" (7/10/05 - Magellan Observatory, Australia): although I've
mentioned this feature on previous observations I was surprised to be
drawn to a 1' circular ring of stars just north of the geometric center
which is mainly filled with unresolved glow and appears like a darker
"hole" near the center. A second smaller and less distinct 30" ring of
stars and darker center is adjacent to the south with the two rings
externally tangent in the middle. After the observation I check John
Herschel's description and found these comments on the star rings in
the center: "One of these rings, 1.5' in diameter, is so marked as to
give the appearance of a comparative darkness like a hole in the
centre...My attendant (J.S.) called up, who saw the hole and darkness,
and described it as I have done above. On further attention the hole is
double, or an oval space crossed by a bridge of stars. Position of axis
= 150."
Received on Fri Oct 14 17:11:20 2005