An Inexpensive Rooftop Fireball Patrol

Fireball Monitor
Edward Albin's fireball monitor keeps an eye out for bright falling stars in the skies over Atlanta, Georgia. Meteors brighter than 1st magnitude are recorded by the video camera mounted above the fisheye mirror.
Courtesy Edward Albin
The whole thing cost just more than $200, it requires virtually no maintenance except a once-a-month dusting, and it provides a useful service that hasn't been widely available before. And it may just be the start of something big: an all-sky, all-night fireball monitoring program.

Edward Albin, an astronomer at the Fernbank Science Center in Atlanta, built and set up the video system two months ago on the roof of his home just outside Atlanta (to avoid the city's light pollution at the science center itself). Having received many calls from the public over the years with reports of apparent fireball sightings, he decided that it would be useful to have a way to check back when such accounts come in. He could then both confirm that it was indeed a fireball — potentially staving off some UFO reports — and provide details of the meteor's time and heading. Similar systems have been set up by Sandia National Laboratory.

Albin built the simple setup from a hemispherical, acrylic "corner mirror" like the ones that help you avoid shopping-cart collisions in the supermarket. He mounted the foot-wide (30-centimeter) mirror horizontally on a cut-to-size piece of plywood, and secured it with a silicone adhesive. Initially condensation occasionally formed on the mirror, but that problem disappeared after Albin put a small electric heating pad inside the dome.

A bright Perseid meteor
Edward Albin's fireball monitor would easily snare bright meteors such as this Perseid captured by Russell Sipe. Notice the color changes in the 'tail.'
Courtesy Russell Sipe.
A simple metal-rod tripod supports the downward-pointing video camera above the mirror, providing a full-sky fisheye view. The 12-volt, black-and-white CCD camera, obtained from a surveillance video company, has a sensitivity of 0.0003 lux, allowing it to pick up stars to 1st magnitude, Albin says. The camera is enclosed in a piece of PVC pipe with a cap for weather protection. Once a month, he goes up on the roof to clean the apparatus, which mostly means removing spider webs.

The images are captured on a standard VHS recorder in the house, connected by standard coax to the setup on the roof's ridge line, using 8-hour tapes (up to two per night in winter). At present, he checks the tapes only if there is a fireball sighting.

An informal network of such simple and inexpensive devices could make it possible not only to establish the time and direction of any fireballs observed in the area, but potentially to triangulate the paths and get detailed elevation and position data, Albin says. But even individual monitors can provide useful information at relatively low cost. "It is amazing how many fireballs and bolides have escaped capture on video, even in our modern techno-gadget age," he says.