NGC 188 image captured with Orion ST120 and Mallincam VSS by Rob Lambert

(FOV is approximately 1.5 degrees at 35X)

Discovered by William Herschel in 1825, NGC 188 is an open cluster in Cepheus. It lies far above the plane of the galaxy and is one of the oldest known. Approximately 5,000 light years away, it presents a unique challenge because initially, it is a rather sparse cluster. With a large enough telescope, more stars can be detected if not directly seen within it. It consists of about 130 stars ranging from mag. 12 to 17, thus giving it the impression of a haze in the background in larger scopes. With the wildly varying star magnitudes, it will likely look different in each size aperture. Collectively, the cluster is around mag. 8, but that is deceptive. With the few stars directly visible, it is easy to pass over, especially with smaller apertures. This cluster will present the observer with a distinct challenge just to pick it out from the background.

NGC 6543, the Cat's Eye Nebula, presented an interesting challenge for us this month. Our Challenge participants weren't expecting their views of NGC 6543 to look anything like the Hubble images above, but check out their images, sketches, and observation reports below.  To check out this interesting object yourself, look for NGC 6543 in the constellation Draco using the Skymaps below.

Click on the images for a larger view

NGC-6543 or Caldwell 6 is more popularly known as the Cat’s Eye Nebula.  This one is going to be a real challenge for those with smaller scopes.  At 70X it appears as an out of focus fat star.  It will be easy to miss if not looking carefully.

William Herschel discovered this fine planetary in the constellation of Draco in 1786.  William Huggins was the first to study the spectrum of planetary nebulae and in 1864, discovered that it consisted of hot gas and not stars.  It is one of the most studied planetary nebulae.  Its apparent size can partially be attributed to its 3,300 light-year distance.

With a magnitude of 9.8, it is well within the reach of even 60mm scopes.  However because of its size, it will take significant magnification to sort it out from the background stars where details can be seen.  With larger backyard scopes and high magnification, many details can be seen, though vaguely and nothing like those Hubble photos.

Though the central star is around mag. 11, it can be hard to spot against the brightness of the nebula, especially with scopes below 12”, though it has reportedly been seen with scopes as small as 4”.

Speaking of Hubble photos, by doing a quick search, many spectacular photos of this nebula may be found, like those at the top of the article.  The colors and shapes within it seem endless in variety.  As visual observers though, unless one has a 30” or larger, the real challenge is to just see a few of these details like the central star, the visual bluish color of the nebula, or maybe the two most prominent lobes.  Give it a try.  It will definitely hone one’s observation skills.

This month, we asked our Challenge Participants to:

  -  Describe a wide field view of the nebula.

  -  Describe what they could see at the greatest magnification at which they could see detail.

  -  Observe and describe the two lobes of the nebula?

  -  Observe and describe the halo that surrounds the nebula?

  -  Observe and describe the central star?

  -  Observe and describe the galaxies that are in the vicinity of the nebula?