30-inch Telescope

The 30-inch (0.8-meter) Telescope is the smallest research telescope at McDonald Observatory. It owes its existence to one of its larger cousins, the Harlan J. Smith Telescope.

When the 107-inch Harlan J. Smith Telescope was completed in the late 1960s, its mirror was made of fused silica (quartz), the state-of-the-art material for telescope mirrors at the time. After a central hole was cut out of this large mirror – necessary to allow incoming light to travel into its science instruments – McDonald Observatory decided to use all of the costly glass that was left over.

This left-over glass was cut in half (like layers of a cake), creating two 30-inch mirror blanks. One of them was used to create the mirror for the 30-inch Telescope. The other serves as the primary mirror in McDonald Observatory’s Mobile Laser Ranging System.

The 30-inch Telescope’s mirror is five inches thick and weighs over 250 pounds. It sits at the end of a tube that is almost eight feet long. The entire telescope is housed in a dome that is 20 feet wide.

Construction of the original 30-inch Telescope was completed in 1970. It underwent a refit in 2012 that provided a new telescope tube, mirror box, and mount, along with ancillary systems.

Research on the Telescope

One of the 30-inch Telescope’s greatest advantages is its field of view. The telescope is able to observe a patch on the sky that is three-quarters of one degree across (the full moon is about one-half of a degree across). With this capability, the 30-inch telescope is ideal for large search and survey projects.

The telescope’s observation system is a hybrid, designed for local (in the dome), remote (via a network), and autonomous (robotic) operation.