CCD Imaging for Amateur Astronomers
The advent of amateur CCD imaging has opened up a whole new world for astronomy enthusiasts. Astronomy is the one science left where amateurs still make an important contribution. The reason is simple: there is too much universe for just the professionals. Even with thousands of astronomers working with hundreds of advanced-technology telescopes there is simply too much out there.
For most amateurs, CCD imaging offers the opportunity to extend the capabilities of their telescopes. The objects you see through the eyepiece can now be easily captured and displayed in full color on a computer screen. Because CCDs are much more sensitive than our eyes, the images taken will show far more detail than can be seen visually through a telescope.
Above: The image on the left simulates the view of the Orion Nebula through the eyepiece of a moderate telescope, around 8" in aperture, as seen from a dark location. The image on the right is a CCD photo of the Orion Nebula taken with a 3" refractor, in the light-polluted suburbs, with a quarter moon out! Incidentally, the left image is a 1-second CCD exposure. If it only takes 1 second to equal what your eye can see through a telescope, imagine what ten minutes of imaging can show you!
A New Way to Observe
One of the biggest advances in amateur astronomy in the last few years has been the advent of inexpensive and easy-to-use CCD imaging systems. With one-shot-color cameras that have almost no dark current, computerized telescopes, and full-featured image processing software, taking images of the night sky has never been easier. In fact, taking color images of deep-sky objects is now so easy and fast that it is practically an extension of observing. An amateur astronomer with an 8" telescope and CCD camera can capture images in just 30 seconds that surpass the view seen through the eyepiece of a 30" telescope.
Also, CCDs allow deep-sky observing from light-polluted skies. As more of the world lights up at night, finding a dark observing site gets harder and harder. But CCDs can cut through the light pollution to some extent, and the light pollution can be mostly blocked with light-pollution filters. Also, narrowband filters can be used to block even more skyglow when imaging certain types of objects like emission nebulas.
Above: An image taken with an 8" telescope from light-polluted urban skies (3.5 limiting magnitude), where the object, M17, was barely seen visually through the eyepiece of a larger 11" telescope. Total exposure time was less than 2 minutes!
Some amateurs are interested in going even further. It is entirely possible to rival the abilities of professional telescopes (albeit on a smaller scale). Computerized telescopes offer the possibility of robotic observing -- the observer sits inside his house, nice and warm in the wintertime, and images the sky remotely. The telescope sits outside in the yard, freezing, with a CCD camera in place and takes images of the sky which are displayed on a monitor inside with the toasty observer!
Advanced amateur astronomers have even gone as far as to compliment the science being done at professional observatories. Comet, asteroid, and supernovae searches and studies are conducted by amateurs. Variable star observations are carried out almost entirely by amateurs due to the sheer number of observations necessary. Extrasolar planet studies have been undertaken by backyard astronomers. Amateurs even coordinate their efforts with professionals to watch for unusual events such gamma-ray bursts in the hope of imaging an optical-wavelength counterpart. This type of study can lead to a new understanding of our universe and is at the very forefront of astrophysical studies today. And it is all being done by hobbyists!
CCD cameras open possibilities to amateurs that we might not have considered before. In the past, film astrophotography required hours of exposure time to capture an image. Now, from their backyards, amateur astronomers are taking images which rival the very best professional images. With the rapid advance of digital technology the future of amateur CCD imaging should be even more amazing!