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Astr110 Photography Projects, Fall 2006

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NGC891, David Streng

NGC891

NGC891 is a spiral galaxy approximately 10,000 kly away. A spiral galaxy is the same sort of galaxy as the Milky Way (the galaxy we are in). It is characterized by a large bulge in the center surrounded by a disk. The disk spins, separating the disk into several arms and making the galaxy look like a giant whirlpool when seen from above or below. NGC891 is seen edge on with a dust lane along the equator. In English, this means you are looking at it from the side, not the top, and the center is darker because the dust scatters the light. This makes it look like a dark rift surrounded by a bright halo. Interestingly enough, our own Milky Way looks much the same when seen from earth. The reason is because we are inside the disk, out in one of the arms. So when we look inward, towards the majority of the disk, the Milky Way is being seen edge on and appears much like NGC891, just much, much larger (because we are obviously much closer to it). NGC891 is approximately 3,437,750,000 light years in diameter. That's rather big.

It was originally discovered by one William Herschel, but he mixed it up with another galaxy found by his sister, Caroline, so its discovery was attributed to her for a long time. See the Students for the Exploration and Development of Space website for more details (my primary source of information). Their picture is a wee bit oversaturated though, look how light the background looks.

References:
Frommert , Hartmut, and Christine Kronberg. "NGC 891." SEDS Homepage. 2 Apr. 2006. University of Arizona SEDS. 2 Nov. 2006 <http://www.seds.org/messier/xtra/ngc/n0891.html>.

"Spiral Galaxy." Wikipedia. 1 Nov. 2006. Wikimedia Foundation, Inc. 2 Nov. 2006 <http://en.wikipedia.org/wiki/Spiral_galaxy>.

Right Ascension (J2000) 2:22:33.05
Declination (J2000) +42:20:48
Filters used blue(B), green(V), red(R), and clear(C)
Exposure time per filter 5x30 seconds CVR, 5x45 seconds B
Date observed

November 12, 2006 (BVRC)