Sunday, February 15, 2009

What's in a Name?

NGC 2024, NGC 2244, and NGC 2264 sound rather dry don't they. The names of these nebulae give you no clue to their beauty. It's like the name Sonata No. 14 in C-Sharp Minor, Op. 27, No. 2, doesn't tell you anything about the glories of Beethoven's "Moonlight" Sonata. If instead I told you that these were the Flame Nebula, the Rosette Nebula, and the Christmas Tree Cluster respectively, you might want to have a look at them for yourself. That's exactly what I did last night at the In-Town Observing Session for the South Bay Astronomical Society. (It took place at Ridgecrest School this month. I guess the key situation has been resolved.)

While I found all three of these New General Catalogue objects, I couldn't see the nebulosity around any of them, only the star fields. But with the wonders of photography and some software, look what one of the guys, Ken Munsen, was able to pull out of the light-polluted Los Angeles city skies. (All photos in this blog entry are used with Ken's permission.)

The top photo is of the Flame and Horsehead Nebulae (two for the price of one!) The bright star to the left of center is Alnitak, the left-end star of Orion's belt. The Flame is obvious to its lower left, but you have to look carefully to see the Horsehead off to the lower right. The Horsehead was made famous to us ordinary folk by the Hubble Space Telescope which celebrated its 11th Anniversary in 2001 by publishing a new photo of the nebula. What's so amazing about Ken's photo is that the guys tell me that the Horsehead is very hard to see through amateur scopes even if you are out in the desert at a dark site. And to think that Ken was set up right next to me when he took this photo at Rancho del Mar High School in January!

The photo on the left was taken by Ken at Ridgecrest and is of the most famous of all nebulae, the Great Orion Nebula. In fact, the photo shows all three "stars" of Orion's sword which include many other interesting objects—NGC 1981 and 1977 (top stars), NGC 1980 (bottom stars), as well as M42 and M43 (in the middle). M43 is the little cloud of purple gas just on top of M42.

The technique used to produce these wonders is to take several relatively short digital exposures and "stack" them together to bring out the details. Ken explains:

The shots of M42 I did from Ridgecrest School and they were all done in 30-second increments with 30 images stacked using Images Plus. The Flame and Horsehead Nebula was done from Rancho del Mar school with 30 1-minute images stacked.
Some guys use a digital video camera and then select the best frames and stack them together. However, I am just learning this stuff, so I am not the person to ask for details. If you want to more about the technique, here is a good place to start. Of course, having a really good telescope helps, too.

Besides being Valentine's Day, it was very cold last night so not many visitors came to see the stars. The seeing was pretty good though, steady, but there was a lot of moisture in the air and dew became a problem by 10:00 pm. When my tracking motor had a "fault" at 10:35, my fingers were too frozen for me to want to start a re-calibration (think cold, wet metal), so I packed up. But I didn't leave until I had a look at Saturn and five of its moons through another guy's scope. The rings are almost edge on right now, but we could still see some of the dark line called the Cassini Division. Check out the SBAS website for the time of our next in-town observing session (it'll be in the current newsletter First Light) and come on up to have a look. Visitors are always welcome.

My last photo for this blog entry is of the beautiful Rosette Nebula (NGC 2244). Ken took this photo out in the desert at Red Rock Canyon and used longer exposure times. Thanks very much for sharing, Ken!

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