Wide Field Spectrograph Research Articles

Photographic and spectrographic observations with a reducing camera on the 61 cm NCU telescope

A Reducing Camera designed by Meinel has been constructed and tested on the 61 cm NCU Cassegrain telescope. The basic principle of RC is to reduce the reflector’s f/13.5 to the equivalent f/2.1 such that the Cassegrain focus image can be reduced on a 35 mm film with almost no loss in sky coverage and in resolution but the exposure time is reduced by a factor of 25. The camera is able to obtain stellar spectra. With a grism and a standard lens the dispersion is 450 A mm−1, which is comparable to that required for the MK classification. RC constructure and testing results are reported. The method of a wide field spectrograph and that of narrow band differential photography of RC are also discussed.

Ultra-violet nightglow spectrum from 1900 � to 3400 �

Two spectra of the ultra-violet nightglow from 1900 A to 3400 A have been recorded by a fast wide-field spectrograph during balloon flights from Aire sur Adour, France on 15 September, 1969 and on 5 October, 1970. These two spectra are composed of theOi line at 2972 A, of the molecular oxygen Herzberg band systemA3 ∑u+ →X3 ∑g− and of a molecular band system that seems to belong to the NO δ SystemX2 τ⇄C2X+, situated at 1991 A±4 A, 2060 A±4 A and 2136 A±4 A. Around 2540 A, there is absorption by ozone at the altitudes at which the spectra were recorded (35 km and 40 km). We present our calculated value of ozone absorption at 35 km, and the zenith-horizon variation of the nightglow emission.