APT building No. 3 at Fairborn Observatory containing the three new 0.80m APTs (T10, T11, and T12) and the new 0.60m AIT (T9) under construction for Tennessee State University. From front to back, the telescopes are T9, T10, T11, and T12.

The combined pneumatic and linear stepper motor supports for the primary mirror.

The secondary mirror focus/collimation stepper motors.

The view from the secondary mirror support toward the primary mirror cell.

The air pressure controller, which regulates the pressure to the pneumatic primary mirror supports as the cosine of the zenith angle.

The air pressure regulator mounted under the primary mirror cell.

Top view of the inside of one of the precision photometers showing the neutral-density filter wheel, cooling blocks, and coolant hoses. Just behind the ND filter wheel is a second wheel containing a selection of focal-plane diaphragms.

Bottom view of the inside of a precision photometer showing the housings for the two PMT detectors mounted at right angles to each other with the mount for the dichroic beam splitter between them. Also shown on the left are the CCD acquisition and centering camera with its relay lens, focus control stepper motor, cooling block, and coolant hoses.

Another view of the CCD acquisition camera, cooling block, and focus motor.

Side view of a precision photometer looking through the PMT housing for the Stromgren y channel with the y filter visible at the far end of the housing.

One of two chillers that supply coolant to the precision photometers for the three 0.80m APTs and the CCD camera on the 0.60m AIT.

Closeup of the preamplifier/discriminator and prescaler board used for each PMT channel in the precision photometers. These electronics are mounted inside the environmentally controlled, sealed photometer housings.

The six preamplifier/discriminators for the three APTs mounted in their shields and ready for installation in the photometers. Also shown are two spares.

The main wire-wrap, telescope-control board. The borad has two low-speed photon counters, over-current monitor, high-voltage protection circuit, sidereal rate synchronizer, and the controllers for the ten photometer head, primary mirror, and secondary mirror stepper motors.

The underside of the wire-wrap telescope-control board.

Computer room for the three new 0.80m APTs and the new 0.60m AIT, located between APT buildings 2 and 3.

Telescope control computers for the three new 0.80m APTs (T10, T11, and T12). They are Pentium PCs running the Linux operating system.

After initial debugging operations with the new APTs, the pneumatic primary mirror supports proved to be unsatisfactory. Pictured here is the T10 mirror cell and pneumatic supports prior to their removal from the telescope.

The T10 primary mirror cell after removal of the pneumatic primary mirror supports.

The T10 primary mirror cell after installation of the new mechanical counterweight support system.

Closeup of one of the T10 mechanical primary mirror supports.

Top view of one of the T10 mechanical primary mirror supports before attachment of the brass weights.

Side view of one of the T10 mechanical primary mirror supports in the "mirror light" position.

Side view of one of the T10 mechanical primary mirror supports in the "mirror heavy" position.

Extreme close view of one of the T10 mechanical primary mirror supports in the "mirror balanced" position.