Coming Down off the Mountain

Tuesday, April 11th, 2006 at 03:31 PM by Administrator

Well, our observing run at CTIO is a success. It got a little dicey toward the end with the moonlight just flooding the sky making us have to spend 4 and a half hours in a field we had to spend only 1 hour on the first night, but we got all the fields we wanted to get observed at CTIO (and couldn’t see from Kitt Peak in Arizona, where we will continue this project next month). Although conditions were completely cloudless the entire run (a condition astronomers call “photometric”), we did have a problem with large amounts of seeing (a way of quantifying “twinkling”) on Sunday night, so we may have to re-shoot those fields in the future.

My last night on the mountain, the sky was bright with moonlight and remained so all night, so we were not really able to do any more observations of our fields (without spending essentialy the entire night on one field), so we concentrated on shooting standard stars whose brightness is known, so we can calibrate all our data. This is something we do every night, but it is not a bad idea to have as much data as possible. Since we couldn’t shoot any of our fields between these standards measurements, I targeted the 1-meter at some of the southern skies more interesting sights, including:

• Eta Carinae: Since Dr. Humphreys (who I am observing with) has spent much of her professional career investigating this extremely massive star (likely the most massive in the Milky Way), we targetted it. It saturated the detector in 0.3 seconds, the shortest possible exposure time, but we could see the famous Homunculus nebulae surrounding the star! For much more informationon Eta Carinae go to the Eta Car Treasury Project website.
• 30 Doradus: Also known as the Tarantula nebula because of its appearance, this is one of the of largest star forming regions known.  Essentually a very big version of the more famous Orion Nebula, it resides in the Large Magellanic Cloud and is the home of many relatively young (only a few million years old) high-mass stars (as well as many more recently formed low mass stars).  If you want to get a feel for what we saw, look at Astronomy Picture of the Day for January 6, 2006.
• Omega Centauri: This is one of the Globular Clusters surrounding our galaxy. It happens to be noted for having stars whose spectra indicate higher levels of processed materials (atoms heavier than Helium) indicating it is one of the younger globular clusters orbiting the Milky Way galaxy. I shot images of it in U (near UV), B (Blue), V (Visual), and R (Red), which I hope to use to construct an astronomy lab (or two) on determining the stellar populations of globular clusters.  If Omega Centauri was also Astronomy Picture of the Day for April 16, 2002.
• Centaurus A: This is a dramatic galaxy in radio waves that also happens to be dramatic in the optical. It is a giant elliptical galaxy that has dust lanes cutting across it. I also took multi-bandpass images of this galaxy for use in an astronomical observing class.  Again, you can get a feel for what we saw on Astronomy Picture of the Day, this time for August 6, 2003.
• NGC 3663: This spiral galaxy has the distinction of currently hosing Supernova 2006ax, a Type Ia supernova. The supernova was discovered on March 20 by the Lick Observatory Supernova Search team and I can tell you that as of last night, it still outshown the rest of the galaxy.

After the night was done, we backed up all the data onto DVDs and a portable hard drive (it was over 40 Gigabytes of images, just over 1000 images) and went to sleep. I got up in time to do some laundry (yes, the mundane aspects of living do catch up with you), packed, and came down in the carry-all. Tonight we will unwind at a local Pizza shop in La Serena, then tomorrow we fly home. I am looking forward to being home with my family, but this was quite an adventure.

And the adventure doesn’t quite end… last night I found I will be observing at the 90-inch Bok telescope on Kitt Peak in Arizona in late May as a continuation of this project. My summer student and I will be very busy this summer turning these images into a measurement of the distributionon of thick disk stars in the Galaxy.

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