Hi George,
Very nice OR for a moonlit night.
I don't observe doubles much - saving the bright stuff for my later years.
Your report encourages me to try some out sooner.
>I started off with Polaris as I use it for adjusting my 1x red-dot finder,
>and knew that the seeing was pretty soft. Usually at 32x the mag 9
companion is
>pretty easy, but not tonight , although with the larger split at 67x it was
>clear. I did run into a problem, however. How do you figure out the
position
>angle of the companion of Polaris? Usually I use Polaris to determine
north, and
>the drift of stars in the field to set east and west. Anyone have a good
way
>for an alt-az user to figure it out solely by observation?
With an alt-az mount, it is difficult to determine the position angle when a
star is close to either celestial pole.
One way is to wait, say, 5000 years. Polaris will have moved quite some
distance (approximately 25º) away from the North Celestial Pole (NCP). Or,
if you wait 14,000 years, Vega will be the North Star and Polaris will be a
comfortable 50º away from the NCP. However, if you lack patience, another
way would be to use a good star atlas. You can compare the angle between the
pair relative to the orientation of nearby stars.
Your post does bring up an interesting question. If the primary star of a
double is located precisely at either celestial pole, how do you determine
position angle? I couldn't find an answer for this special case. I suspect
you could use define position angle relative to zero hours of Right
Ascension.
>I ended up with 7 other doubles: eta Cas, gamma And, gamma Ari, lambda Ari,
>iota Tri, eta Per, and the Trapezium (does it count as 2?).
>The best colors were on gamma And, lambda Ari and eta Per. My color
>perception is not great, but to my eye I saw yellow primaries and bluish
secondaries on
>this trio. What colors do other folks see?
I regularly look at gamma Andromeda. Its members look yellow and blue to
me - a fainter, closer-spaced version of Albireo. The secondary star in eta
Cassiopeia looks coppery to me in a 6" or larger scope.
Albert