We describe the University of Vienna twin automatic photoelectric telescope (APT) located at the new Fairborn Observatory at Washington Camp in southern Arizona. Not only are the telescopes fully automatic, but the observatory itself is automatic. A site-control computer monitors weather sensors and operates the roof while the telescope control computer operates the photometer and accepts input files from and provides nightly observations to the astronomer; no direct operating personnel are needed. Both telescopes have 0.75-m primary mirrors, a CCD finder camera, and an environmentally controlled single-channel photoelectric photometer with filter combinations optimized for use in the blue (Wolfgang) and in the red (Amadeus) wavelength regions. The telescopes are currently used for monitoring spotted stars, for asteroseismology of nonradially pulsating variables, and for monitoring asymptotic-giant-branch stars. Some first results are presented.

We review the factors limiting the precision of differential stellar photometry. Errors due to variable atmospheric extinction can be reduced to below 0.001 mag at good sites by utilizing the speed of robotic telescopes. Existing photometric systems produce aliasing errors, which are several millimagnitudes in general but may be reduced to about a millimagnitude in special circumstances. Conventional differential photometry neglects several other important effects, which we discuss in detail. If all of these are properly handled, it appears possible to do differential photometry of variable stars with an overall precision of 0.001 mag with ground-based robotic telescopes.

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Abstract.A cross-dispersed spectrophotometer with a back-illuminated uv-coated CCD detector and its automated 0.5-m telescope at the Fairborn Observatory, Washington Camp, AZ now under construction, should begin scientific observations in the Spring of 2005 . The Citadel ASTRA (Automated Spectrophotometric Telescope Research Associates) Telescope will be able to observe Vega the primary standard, make rapid measurements of the naked-eye stars, use 10 minutes per hour to obtain photometric measurements of the nightly extinction, and obtain high quality observations of V = 10.5 mag. stars in an hour. The approximate wavelength range is λ 3300-9000 with a resolution of 14Å in first and 7Å in second order. Filter photometric magnitudes and indices will be calibrated in part for use as quality checks.First a grid of secondary standards will be calibrated differentially with respect to Vega. They will also be used to find the nightly extinction. The candidates were selected from the most stable bright secondary stars of the grating scanner era, the least variable main sequence B0-F0 band stars in Hipparcos photometry, and metal-poor stars. Continued measurements of secondary stars will be used to improve the quality of the secondary standard fluxes. Science observations for major projects such as comparisons with model atmospheres codes and for exploratory investigations should also begin in the first year of scientific observations. The ASTRA team realizes to deal with this potential data flood that they will need help to make the best scientific uses of the data. Thus they are interested in discussing possible collaborations. In less than a year of normal observing, all isolated stars in the Bright Star Catalog that can be observed can have their fluxes well measured. Some A star related applications are discussed.