Technical aspects of the new AAO/UKST Hα interference filter

Abstract

We briefly describe technical aspects and specifications of the new UKST Hα interference filter, which is probably the largest of its kind available in astronomy. Preliminary exposures show that the filter gives excellent imaging with high overall transmission and uniformity at Hα wavelengths. This is achieved over a circular area of about 305 mm diameter or about 5.7 degrees (the so called 'clear aperture'). The prospects for the new UKST Hα survey of the southern Milky Way with this new filter are excellent.