The largest and most visible scientific instruments on the PARI campus are the two 26 meter (85ft) radio telescopes.  Originally constructed by NASA for communications with satellites and spacecraft, the antennas could move at 3° per second across the sky. Weighing 750,000 pounds, with foundations extending 85 feet down into bedrock, the PARI 26 meter antennas were built to last. PARI has invested more than $3 million to enhance the telescopes and adapt them for the slow motion 15° per hour celestial tracking used in radio astronomy.

Students from NC A&T State University in Greensboro improved the mechanical balance and precision of each antenna by tuning the placement of counterbalance weights on each antenna and measuring the surface accuracy of the parabolic portion and feed placement.

Through a collaborative effort with PARSEC, the radio telescopes are being combined into a two-element interferometer.  Funding has been received by Principal Investigator Dr. Brian Dennison (UNC-Asheville) to develop sensitive 2.2 GHz and 8.4 GHz receivers for each radio telescope.  The interferometer will be used for observations of an astrophysical phenomenon called IntraDay Variables (IDVs). IDVs are unseen clouds of matter in the Milky Way Galaxy. PARI’s radio telescopes will measure changes in brightness from distant normally constant radio sources as they become obscured by these clouds of matter.  The project will require several years to complete.

Additional upgrades are underway to add improved pointing accuracy, fiber optic cabling and feedbox temperature control to each antenna as part of grants from NASA and the National Science Foundation. The fiber optic cabling adds stability to receive signals, immunity to storm-induced lightning damage, enhanced reliability and reduced maintenance costs. Another student project, temperature control of the feed electronics, improves sensitivity and accuracy of data taken by each antenna.

Students from NC A&T, UNC-Asheville, and Furman University are working on the design of a movable feed cartridge assembly to provide motorization of focus adjustments, which will allow each antenna to be readily reconfigured to serve a wide complement of frequencies as needed for new projects.