In Figure 10 (528 Kbytes) we show an image of the LMC taken in Red light. In this passband one measures the intensity and appearance of the galaxy in the light of stars which are about 5 billion years old. In Figure 11 (354 Kbytes) we show a narrow band H-alpha image of the LMC which traces the emission from gaseous regions that are ionized by stars with ages less than 10 million years. The dramatic difference in the appearance and structure of the galaxy, as outlined by these two different age stellar populations, should be obvious and again serves as a reminder of the wavelength dependence of galaxy structure.
Lastly, we include in Figure 12 , another image taken with Parking Lot CCD. This is a short exposure blue band image of the Local Group Galaxy IC1613. At sensible pixel resolution this galaxy is well resolved into stars which indicates the galaxy to have a distance of about 1 Mpc from us. This resolution, however, belies its true nature and Figure 12 in essence, is what this galaxy would look like if it were placed at a distance of 40 Mpc from us. In this case, IC 1613 is then a very diffuse galaxy, similar to the low surface brightness galaxy shown in figure 1.
In the final image , we feature the work that amateurs can do using commercially available CCDs. This picture was taken with an ST6 at the Oregon Star Party in August of 1994. A 75-mm lens plus rack and pinion focusser was mounted to the ST6 giving an 8 degree field size. This unit was then placed in a wooden Dobsonian mount and pointed up at the sky for 15 seconds in order to capture the faint aurorae that were occurring.
In sum, this article has summarized the various systems that are capable of performing wide field CCD imaging. Some solutions are quite expensive in terms of detector technology and data processing time. Other solutions are practical for the amateur astronomer. The most important point to stress is that the very high quantum efficiency of today's CCD means that a telescope is not necessarily required to detect the light from faint objects. A simple, inexpensive lens system can provide a very large field of view for amateur CCDs which don't have many pixels. Hence, for all you amateurs that want to perform your own Supernova search, or find comets or asteroids, or to simply have your own private sky survey, you might consider using your telescope as the tracking device as the CCD +lens system rides parallel, giving you a degree slice of the sky per exposure.
I would like to acknowledge the following collaborators for assistance with this article:
Figure 1: Mark Cornell and David Chappell - McDonald Observatory, University of Texas
Figure 2: Andrew Fructher, Space Telescope Science Institute
Figure 3: Taft Armandroff, Kitt Peak and Nelson Caldwell, Mt. Hopkins
Figure 4: Christopher Stubbs, University of California, Santa Barbara
Figure 5: Greg Aldering, University of Minnesota
Figure 8: Jamey Eriksen, San Diego State University
Figures 10--12: Ian Thompson, The Observatories, Pasadena CA
Figure 13: Mel Bartles, Friends of Pine Mountain