A charge-coupled device (ccd) transit-telescope survey for galactic and extragalactic variability and polarization

We describe a new instrument and data handling scheme which will automatically carry out a photometric survey for variable objects to a limiting magnitude of about 20, and a polarimetric survey for objects which are 1% or more polarized, to a limiting magnitude of about 18. The instrument consists of a dedicated 0.76m, f/4.7 Newtonian reflector which is used as a transit telescope, and two area-format CCDs which are placed in the focal plane and clocked at the sidereal rate. An effective integration time on a point on the sky of about one minute is achieved by this technique. We discuss the photometric advantages of “averaging over” all spatially dependent noise sources when CCDs are used in this way. The system noise and dynamic range of the instrument are discussed assuming the use of RCA thinned, buried-channel CCDs. Two astronomical projects, the definition of a homogeneous, unbiased, sample of QSOs, statistically complete to about 20th mag, and the discovery of supernova outbursts on the rising branch of the light curve, are described. A list-oriented real-time data compaction scheme is proposed to allow easy management of the vast amount of data generated by this instrument.