Bochum Scanner

The Bochum Scanner began operations on the Cassegrain focus of the Bochum 0.61-metre telescope at La Silla Observatory in 1973. The single-channel rapid spectrum scanner was designed by R. Desjardins and W. Haupt and built by the Zentralwerkstatt Göttingen GmbH, in Göttingen, Germany.

The Bochum Scanner was initially used to classify red giants and red supergiants and determine emission line profiles of Wolf-Rayet stars and X-ray stars, and then extensively of Be stars. The instrument was also used to observe supernova SN 1987A and through optical spectrophotometry collected key information about the physical conditions of the photosphere and the layers above it. It was also extensively used to measure the energy distributions of spectrophotometric standard stars.

The Bochum Scanner was a monochromator. This device transmits a mechanically selectable narrow band of wavelengths of light onto a single-channel detector. The scanner used a crossed Czerny-Turner configuration and a grating ruled with 1200 grooves/mm that was rotated by a computer-controlled stepping motor through a precision screw. The device was known for its high linearity and stable resolution. By design it had a low efficiency.

The device was connected to a computer, which acted as a multichannel scaler for the photoelectric detector and controlled the scanner. Computerising the scanner came with advantages, such as digital data, automatic measurement processes and quick-look data checking directly after an observing run.

The Bochum Scanner is decommissioned.