The bright star Gamma Cas
is attended by two large wisps of nebulosity, IC 59 and IC 63.
Gamma Cas is the middle star of Cassiopeia, a 2nd magnitude star
that is the prototype for a class of eruptive variable stars.
It varies from a maximum of 1.6 magnitude during an eruption to 3.0
magnitude when the mass it is expelling from its equator blocks some
of its light.  IC
59 lies about 20' to the north of Gamma Cas. It is primary a
refection nebula, appearing blue in photographs from scattered
starlight that is passing through it. Like the blue sky over
your head, some of the light passing through is scattered away, and
blue light is scattered more than red. This light
probably originates from nearby Gamma Cas, which may also have shed
this nebulous material into the space around it.
IC 63 lies about 20' to
the east-northeast. This nebula is a combination of HII region
and reflection nebula. Unlike a reflection nebula which
appears blue, the glowing hydrogen gas appears red in photographs.
It's not clear how much
aperture is necessary to observe these nebulae. For best
results you should use an eyepiece that provides a fairly wide field
of view (at least 10') yet not so large that you can't keep the
bright Gamma Cas out of view. Because much of the light is due
to reflection, neither of these nebulae respond well to OIII or
H-Beta filters.
IC 63 is the brighter
of the two and the easiest to spot. Look for a hazy,
fan-shaped region of sky. It will appear very diffuse with no
discernible edges, rather unlike the photograph above. If you
can spot IC 63, then have a try at IC 59. This nebula is a
little fainter and perhaps even more diffuse. It looks like a
roundish patch of sky that is just ever so much brighter than the
surroundings.
I had little difficulty
observing both of these on a nice dark night with my 18-inch f/4.5
Dob.
Half way between IC 59
and IC 63 lies a small nebula. This appears to be IRAS
00556+6048. If you are looking for a challenge, this might
prove an interesting target. I haven't tried for it yet and
I'd be interested in hearing if anyone has seen it. Relatively
high magnification, perhaps 300x, might help make it visible.
IRAS 00556+6048. North
is down and east is to the right. |
