Zenith camera

Zenith cameras are designed as transportable field instruments for the direct observation of the plumb line (astronomical latitude and longitude) and vertical deflections.

Because zenith cameras are usually designed as non-tracking and non-scanning instruments, exposure times are kept short, at the order of few 0.1 s, yielding rather circular star images.

Depending on the CCD sensor - lens combination used, few tens to hundreds of stars are captured with a single digital zenith image.

The zenith point is interpolated into the field of imaged stars, and corrected for the exposure time and (small) tilt of the telescope axis to yield the direction of the plumb line.

Zenith cameras with CCD image sensors are efficient to collect vertical deflections at about 10 field stations per night.