Comets

Nothing spurs astroimagers to action like a rare astronomical phenomenon.  Even non-imagers are tempted to take a few shots during a newsworthy event.  A relatively bright comet might come along every few years, but a truly spectacular one, like Comet Hale-Bopp, is more often a once-in-a-lifetime event.  Hunting for comets has always been an exciting possibility for amateur astronomers.  While new professional astronomical surveys are making amateur comet discoveries less frequent, the advent of impressive CCD technology available to the average dedicated amateur has made is possible to compete with the big boys at finding some of the solar system's most beautiful and mysterious family members.

Asteroids

Asteroid discoveries are now commonplace among amateur CCD imagers, but a near-Earth asteroid discovery is still a relatively unusual find for amateurs.  Also, even if you are not interested in finding an asteroid, occasionally one comes close enough to Earth to become fairly bright and to be easily imaged.  Near-Earth asteroids (NEAs) have the distinction of being one of the few astronomical objects to show a distinct motion against the background stars in a very short time.  Comets, of course, move as well, but usually the motion is slow, changing noticeably only over many minutes or hours.  An NEA might, however, be seen to move through a telescope in less than a minute due to its proximity to Earth.  Also, scientific data can easily be captured by the amateur imager and contributed to scientific studies that advance our knowledge of the solar system.

Supernovae

Supernovae, the violent deaths of massive stars, occur, on average, once every hundred years in a given galaxy.  This would seem to make these stellar explosions infrequent occurrences, but given how many galaxies can be seen with even a small telescope and CCD camera, supernovae are actually fairly common sights.  At least in other galaxies.  What about our own Milky Way?  The last galactic supernovae was seen in 1604.  It appeared as bright as the planet Jupiter, and the previous galactic supernova, only 32 years earlier, was brighter than Venus!  No supernovae have been seen in our galaxy since before the invention of the telescope, let alone since the invention of CCD cameras!  We are nearly 300 years overdue for a spectacular show, but in the meantime we can watch the fireworks millions of light years away without leaving our backyards!

Capturing each of these events with a CCD camera requires certain techniques, outlined below.  Hunting for these elusive targets can be a consuming undertaking, and all the details of searching the night sky for transient phenomena could fill a book (or a whole other website) so only the basics are discussed.

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