There are six star-plates available containing fixed slits, each with a length of 8 arcminutes. The available widths are 0.5 arcsec 1.0 arcsec 1.5 arcsec 2.0 arcsec 5.0 arcsec 10 arcsec. The 0.5-arcsec slit will cause undersampling of the spectra. The 10-arcsec slit has ragged edges but this is unlikely to affect the observations. There is no TV camera for the star-plate unit.
Acquisition is done using the possibility to take direct images through the slit.
First the projected position of the slit on the CCD is determined using one of the internal lamps. An image of the field is taken through the 'free' position, and the position of the target is determined. The target can now be moved to the projected slit position by offsetting the telescope. A final check can be made by taking a direct image through the slit.