February 27-March 6, 2009: constellation Columba, globular cluster NGC 1851, and spiral galaxy NGC 1808

Posted by Michael Bakich
on Thursday, February 26, 2009

Columba the DoveHere is the transcript for my podcast about how to see constellation Columba, globular cluster NGC 1851, and spiral galaxy NGC 1808 this week.

Check out the Astronomy.com's interactive star chart to see an accurate map of your sky. It'll help you locate some of this week's key targets. Astronomy magazine subscribers have access to a slew of cool functions with StarDome PLUS.

Each week, I highlight three different night-sky targets for you to see:

  • One object you can find with your naked eyes or through binoculars
  • One object to find with a small telescope
  • One deep-sky object to find with an 8-inch or larger telescope for you avid astronomers

--Start transcript--

Biblical astronomy
This week’s naked-eye object is the constellation Columba the Dove. Specifically, it represents the dove that Noah sent out to test whether the waters from the great biblical flood had receded. It’s the only surviving constellation named after an object in the Bible. Columba first appeared in 1592, on a celestial map designed by Dutch astronomer and cartographer Petrus Plancius.

Columba is a constellation most amateur astronomers haven’t identified. Well, here’s your chance. Find Orion. That’s easy enough. Now look south of Orion, and find Lepus. I showed you how to locate this constellation 5 weeks ago. Finally, continue south from Lepus, and you’ll end up in Columba.

You’ll first notice the constellation’s two brightest stars. Phact (Alpha [α] Columbae) shines at magnitude 2.6, and Wasn (Beta [β] Columbae) isn’t far behind at magnitude 3.1. From there, use a star chart to find just three other stars brighter than 4th magnitude. Then all you have to do is make a dove out of those stars. Good luck.

When you look at Columba, you might want to wave goodbye. This constellation contains the point in the sky away from which our solar system is heading, relative to stars in our neighborhood. Astronomers call this point the solar antapex.

For those of you with large telescopes, there’s something at the approximate coordinates of the solar antapex. It’s the magnitude 13.2 galaxy IC 2153. Warning: Unless you can set up a large telescope at a dark site, you won’t have much luck observing this small faint object.

Alone in the dark
This week’s small telescope target is globular cluster NGC 1851 in Columba. It sits nearly 8° southwest of Phact, but you’ll see it easily from a dark site through binoculars. This magnitude 7.0 globular is the brightest deep-sky object for more than 20° in any direction.

Through a 4-inch telescope, you’ll see a concentrated core that you can’t resolve surrounded by many stars you can.

NGC 1851’s core is difficult to resolve through large telescopes as well because of its distance. It lies 40,000 light-years from the Sun and 55,000 light-years from the Milky Way’s center.

Bright, but few details
This week’s deep-sky object completes my trio of “Columba” objects. It’s spiral galaxy NGC 1808. This galaxy shines relatively brightly at magnitude 9.9.

NGC 1808 is easy to see and accepts high magnifications well because it has a high surface brightness. The galaxy’s oval shape — twice as long as it is wide — is apparent, but you’ll only see the initial stubs of the faint spiral arms that long-exposure images show stretching around NGC 1808’s entire length.

Through a 16-inch or larger telescope, crank up the power, and try to see the dark lanes near the galaxy’s outer edge. Astronomers recently discovered this galaxy has a high amount of star-formation occurring within it.

For those of you with the largest amateur scopes, three challenging galaxies lie roughly 10' southeast of NGC 1808. The brightest, PGC 620467, glows weakly at magnitude 15.6. The other two, PGC 131395 and PGC 16804, are really faint. Both of these galaxies have magnitudes of 15.9.

---End transcript--

Previous episode: Beehive Cluster, open cluster M50, and the Rosette Nebula
Previous transcript

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