Report from CTIO: I saw the Magellanic Clouds last night!

Friday, April 7th, 2006 at 03:27 PM by Administrator

(Click on image for full-size version.) This is an image of the center of the Milky Way and The Magellanic Clouds over the CTIO 4-m telescope. I did not take this picture and the orientation of the sky is a bit different right now (the Magellanic Clouds are lower), but it gives you a small taste of the grandeur of what I am seeing here. And it was taken some right outside the telescope I am using. (Courtesy: NOAO)

Well, our second night of observing at the Smarts/Yale 1-meter at Cerro Tololo Inter-American Observatory in Chile went well except for about 25 minutes lost when we started seeing out of focus shadows on the images. It turned out we had a bit of lose tape inside the filter wheel. The night operator removed the tape and we were running again. Other than that, our biggest enemy has been the moon. Our project involves shooting realtively deep wide-field (1 degree square) images to count the number of stars from one component of the Milky Way (the galaxy we reside in), the thick disk. By counting the number of thick disk stars that lie in certain directions on the sky, we hope to determine the origin of an asymmetry in the distribution of these stars seen in the sky. The moon is approaching full so each night we lose a bit more of the night, since when the moon is up we have to image each field for a lot longer in order to see faint objects. This combined with the seeing (1.5 to 2 arcseconds at this telescope, actually not horrid, but not pristine) has made it difficult to see the fainter stars in images shot when the moon is above the horizon. That is the life of an optical astronomer.

My collaborator, Dr. Roberta Humphreys, insisted I go outside for at least 10 minutes outside and let my eyes dark adjust. It may seem amazing, but when you are observing a program like ours, so much is going on that the longest stretches of time you can step away from the computer are only minutes in duration. Dr. Humphreys has spent many nights here at CTIO and insisted I had to see the night sky here with my eyes dark adapted. I was glad she pushed me, the sky outside was spectacular once the moon was down and I gave my eyes time to adjust. I thought previous night’s view had been spectacular when I stepped out for 5 minutes, but last night, after about 10 minutes, I was almost able to read by the light shining from the center of the Milky Way. I could even see the Small and Large Magellanic clouds, despite the fact that these small galaxies that orbit the Milky Way were very low on the horizon … they were faint, but clearly visible. The dust lanes of the Galaxy lept out at me. I have heard that the cultures down here had “dark constellations”, that is, they attached mythological figures not only to patterns in the stars, but patterns in the shapes of the areas without stars. Its going to be a bit of a disappointment to come back to the light polluted skies of central Minnesota after this. I hope my proposal for time in the fall goes through so that I can come back here.

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