| IC
443 |
Supernova
Remnant
aka
SNR 189.1+03.0, Sh 2-248, LBN 844
Integrated
Visual Magnitude: 12
Apparent
Diameter: 50'
Minimum
requirements to view: 8-inch scope, OIII filter and very dark
skies |
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IC 433 is a supernova
remnant that was once only visible in photographs and very large
telescopes. Specialized, narrow band filters, such as the UHC
or OIII, have changed this. With an OIII filter in place the
brighter portions of this nebula are now within reach of experienced
users of 8-inch or larger telescopes observing from a dark location.
A spectacular object in
photographs, only the brightest regions are visible in the typical
amateur telescope.
I first observed IC 443 in
January 2001 with my 18-inch f/4.5 Dob. I was only able to
make out this nebula with the OIII in place, perhaps due to the
unusually bright sky on that night. At 94x I was able to see
the brightest (southern) portion of the large arc, appearing a bit
like a curved, 4-day old moon. 
The field in an 18-inch
at 94x (22mm Panoptic). The bright star to the upper left is
Eta Gem. The brightest portion is the small, arc-shaped knot
on the lower left. North is down and east is to the right.
The supernova that created
IC 443 probably occurred some 3000 years ago. As the shock and
debris from the explosion spread outward it met a nearby molecular
cloud complex. The interaction resulted in the filimentary
structure we see in photographs. A molecular cloud complex is
a region of cold, high-density gas. It is out of such cloud
complexes that stars can form, sometimes triggered by the passing
shock of a nearby supernova. Interestingly, the
remains of a much older supernova remnant (possibly as old as
100,000 years) can be seen in silhouette in x-ray images.
Links:
IC
443 in X-rays
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Millennium
Star Atlas Vol I Chart 156
Sky
Atlas 2000 Chart 5
Uranometria
2000 Vol I Chart 137 |
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