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NGC 891 is an edge-on spiral galaxy located some 10 million light years away in the direction of the constellation Andromeda. NGC 891 has a large dust lane that is typical of spiral galaxies. It is often studied as a model of the Milky Way, as it is thought to be quite similar to our home galaxy.
This composite image was obtained using the 200-inch Hale Telescope's Wide-field Infrared Camera at Palomar Observatory by Kevin Bundy of the California Institute of Technology and at the 10-meter W.M. Keck Observatory's Low Resolution Imaging Spectrograph (LRIS) by Patrick Shopbell and Judy Cohen of the California Institute of Technology. Yellow colors in this composite correspond to the near-infrared image which was obtained at Palomar. The blue colors correspond to the visible light image which was obtained at Keck.
This kind of representation is useful because it demonstrates the utility of observing at many wavelengths. Because the central bulge of NGC 891 appears yellow in the composite, it is clear that the infrared does a better job penetrating the dust lane of this galaxy, which almost completely obscures the bulge in the optical image.
The Palomar image is the result of the addition of twenty separate frames taken in the Ks filter at 2.2 microns, this observation required a total exposure time of 15 minutes.
full sized greyscale version of the Palomar image (705 kb)
mediuim size version of the Palomar image (281 kb)
The research was based on observations obtained at the Hale Telescope, Palomar Observatory, as part of a collaborative agreement between the California Institute of Technology, its divisions Caltech Optical Observatories and the Jet Propulsion Laboratory (operated for NASA), and Cornell University.
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