1. Instrumentation
Since our last report the two solar telescopes near G6ttingen (Cassegrain-coelostat) and at Orselina near Locarno (Gregory-Coud6) have been improved in the following points:
A. The equipment at the Ha&berg station has been supplemented by equipment from Locarno: (l) Simultaneous slit jaw imaging in Ha and white light, the latter via broadband filter on either a projector screen or TV. (2) Adapter for the Locarno image intensifiers (cf. (6e)).
(3) Divider electronics for line-to-continuum recording. B. At the Locarno station the main improvements (cf. Schr6ter, 1975; concern:
(1) Complete reconstruction of the f = 25 m telescope (cf. Figure ) with (a) evacuation (~<0.5 torr) between two BK7 windows, one of Q = 50 cm, d = 8 cm at the telescope's entrance, and one of ~ = 5.5 cm, d = 0.7 cm at the hour axis 45 cm in front of the spectrograph slit (cf. Figure ), and (b) new telescope mirrors now made of ZERODUR (for image quality see frontispiece Solar Physics, Vol. 65, No. 1). (2) Zeiss guiding telescope (~ = 5 cm, f = 274 cm) movable in a and 8 relative to the main tube by means of two computer-controlled stepping motors (1 step = 0"188; cf. Wittmann, 1980). (3) Auxiliary refractor (~ = 10 cm, f = 150 cm) with Ho~ filter and TV camera (cf. Figure ) for locating the 200" field of view of the main telescope on a = 17 cm TV image of the entire disc. (4) Slit-jaw imaging device for simultaneous observations in Ca + K, Ho~, 4100<A <6400~ on TV (0.7" ram-l), 35 mm cameras (13.3" mm -1) or a rotatable projection screen (1.44" mm -1) compensating the Coud~ rotation (cf. Figure ). ( ) Honeywell H316 computer (16 bit words, 8K memory) for data processing, data storage on magnetic tape and control of numerous devices, viz.: (a) The wavelength scale of the preselector (f = 1 m, ~ = 50 cm mirrors) via a prism driven by a stepping motor;