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Observing podcast: Double star Eta Cassiopeiae, M32 and NGC 205, and spiral galaxy NGC 7814

October 14-21, 2010: Double star Eta Cassiopeiae makes a nice target for beginning observers, while M32, NGC 205, and spiral galaxy NGC 7814 provide nice targets for telescope owners.

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Cassiopeia houses many dazzling objects. Orient yourself by facing north. Tilt your head back so south is at the top of your view. Cassiopeia will be just about overhead.
Roen Kelly
Each week, Astronomy magazine Senior Editor Michael Bakich, a master at explaining how to observe, posts a podcast about three objects or events you can see in the sky. In each episode, Michael highlights:
  • One object you can see without any optical aid
  • One object you can see with a small (4-inch) telescope
  • One object you can see with at least an 8-inch telescope
Targets for October 14-21, 2010
    Naked eye: Double star Eta Cassiopeiae
    Small telescope:
    M32 and NGC 205
    8-inch or larger telescope:
    Spiral galaxy NGC 7814
Listen to the podcast:


Jewels in the Queen's crown
This week's first target is the double star Eta Cassiopeiae. This colorful binary lies 1.7° northeast of magnitude 2.2 Schedar (Alpha [α] Cassiopeiae).

The two components shine at magnitudes 3.4 and 7.5, and their separation is 12.9". Low power works best to bring out the yellow color of the primary and the reddish hue of the secondary. Magnifications above 100x accentuate the brightness difference between the two, making them appear more white and yellow, respectively.

The origin of the common name for this star, Achird, is a mystery. It must be a 20th-century addition. Stellar nomenclature expert Richard Hinckley Allen mentions the star as a nice double but says nothing about the name in his classic Star Names and Their Meaning, which appeared in 1899.

Bright, but hardly noticed
This week, my second object gives you two targets for the price of one. It's the pair of bright elliptical galaxies — M32 and NGC 205 — that flank the Andromeda Galaxy (M31). I guess that could be three-for-one, but, just this once, I want you to ignore M31. Good luck with that!

M32 shines at magnitude 8.1 and lies 0.4° due south of M31's heart. It measures 11.0' by 7.3', but it shows no features through any size telescope.

You'll find NGC 205, the second member of the pair, 0.6° northwest of M31's core. While NGC 205 also shines at magnitude 8.1, this elliptical is nearly three times larger. It measures 19.5' by 12.5'. Even through large amateur telescopes, you won't see much detail in this galaxy.

If you read enough about amateur astronomy, you'll eventually find some sources that list NGC 205 as M110. People have defined French comet-hunter Charles Messier's list in many ways. Here at Astronomy magazine, we define the list as containing 109 objects.

In fact, Messier stopped his list at 103 objects. That should be the definitive number. But it would be hard for us (or anyone else) to stop the list there. Imagine not including the Sombrero Galaxy (M104)! We choose to include the six additional objects listed and described by Messier's contemporary, Pierre Méchain, in 1783. That brings the total to 109.

Messier certainly saw NGC 205. In fact, he sketched it and published the drawing in the French journal Connaissance des Temps for 1807. But he didn't include it in any version of his catalog, so neither do we.

Fine spiral in Pegasus
This week's large-telescope target is spiral galaxy NGC 7814 in Pegasus. To find it, move your scope 2.6° west-northwest of magnitude 2.8 Algenib (Gamma [γ] Pegasi). It glows at magnitude 10.6 and measures 6.0' by 2.5'.

From a dark site, even a small telescope will reveal that this object looks like a football, but with more tapered ends. To see more detail, however, you have to step up to at least a 10-inch scope. Through that size instrument, and at a magnification around 200x, you'll see that NGC 7814's central region spans a third of its length.

This galaxy has a prominent dust lane captured by many astroimagers. You'll need a huge telescope to have a chance to see it, however. Through a 20-inch scope, crank the magnification past 400x, and carefully look for two thin, dark lines that emanate from points outside the core. Follow the lines outward to the ends of the spiral arms.

stardome330
Expand your observing with these online tools from Astronomy magazine

Star Dome
Check out Astronomy.com's interactive star dome to see an accurate map of your sky.  This tool will help you locate this week's targets.

Observing Talk
After you listen to the podcast and try to find the objects, be sure to share your observing experience with us by leaving a comment at the blog or in the Reader Forums.
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