T12 0.80 meter APT

Observing Program

The T12 0.80m APT became operational in the Fall of 2000 at Fairborn Observatory. T12 is a functional duplicate of the T8 APT, including the two-channel photometer on the standard Stromgren b & y system. Funding for the construction and operation of the telescope has come from NASA, NSF, and Tennessee State University.

T12 has completed a 1 yr survey of 93 debris-disk star candidates from the Spitzer Space Telescope "Formation and Evolution of Planetary Systems" Legacy Program, successfully measuring rotation periods (leading to better ages) for 70 (75%) of the sample. This APT has also completed a 1 yr survey of a volume-limited sample of 114 gamma Doradus star candidates, finding intrinsic brightness variability of 0.002 mag or more in 37 (32%) of the stars. More intensive observations over two years with the T3 0.40m APT confirmed 23 of the variables to be new gamma Doradus stars.

T12 is now used primarily to observe planetary-candidate host stars that have been identified in various radial-velocity surveys. The precise brightness measurements made with the APT are important for understanding the nature of the observed radial-velocity variations and confirming the reality of the planetary companions. T12 is also monitoring these stars to search for transits of the planetary companions. The detection of transits, combined with the radial-velocity observations, allows the determination of the planet's true mass, its size, and its mean density. This provides important clues to the planet's composition and origin.


  • 31.5-inch Cassegrain optics of sitall by Star Instruments
  • Primary focal ratio is f/2; effective focal ratio f/8
  • Horseshoe equatorial mount with quadrapod secondary mirror support by Fairborn Observatory
  • Disk and roller drive systems on both axes
  • High-precision, two-channel photometer with dichroic beam splitter from Fairborn Observatory
  • Stromgren by filters
  • Neutral density filters with attenuation of approximately 1.25, 2.5, 3.75, and 5.0 mag.
  • Selectable diaphragm wheel with diameters of 30, 45, 60, & 90 arcseconds
  • Two EMI 9124QB photomultipliers
  • PMTs, voltage divider, preamp, and filters in sealed, environmentally-controlled chamber
  • ATIS93 control system from Fairborn Observatory
  • Construction Photos