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More Galaxies: From the Howk-Savage Science Team!

Chris Howk (JHU) has compiled a gallery of other edge-on galaxies. Both ground and space views of more spectacular galaxies can be found by visiting the gallery. Images courtesy of C. Howk (JHU) and B. Savage (University of Wisconsin-Madison).

An Added Bonus: Hubble Spots a Satellite Trail!


During an HST exposure of a celestial object, the camera occasionally picks up light from objects other than the intended source. During one of the several HST exposures that were combined to make the color image of NGC 4013, a bright artificial satellite (possibly one used for weather, communications, or military purposes; we have not determined which satellite it was) crossed the field of view. This resulted in a bright streak across the image, visible in this reproduction of a single exposure, just above the nucleus of the edge-on galaxy and near the bright foreground star.

During the processing that created the final color image, artifacts that appear on only one of the exposures are removed; thus the streak does not show up in the final picture. As you can see by clicking on this single-exposure image for a closer look, the picture is also covered by a multitude of small specks and short trails, almost as if dust had been sprinkled on the picture. These are caused by charged particles above the Earth's atmosphere, called cosmic rays, which strike the detector during the exposure. Telescope astronomers always try to obtain at least two exposures of the same object in the same filter. With the aid of computer software, they can remove the cosmic rays as well as other artifacts such as satellite trails from the final presentation of the image.

Animation of NGC 4013: Including Ground- and Space-based Data!

Video Zoom of
NGC 4013

1.8MB MPEG
Animation Credit: Bryan Preston STScI AVL

Animation Image Credits

Ground-based image
Credit: C. Howk (JHU), B. Savage (University of Wisconsin-Madison), N. Sharp (NOAO) taken with the WIYN telescope (NOAO/NSF) on Kitt Peak, Tucson, AZ. Copyright WIYN Consortium, Inc., all rights reserved.

HST Image
Credit: NASA and The Hubble Heritage Team (STScI/AURA). Acknowledgment:
C. Howk (JHU), B. Savage (University of Wisconsin-Madison).