A stabilized large-aperture far-infrared telescope gondolaDescription of a recently developed balloon-borne 1-m far-infrared telescope designed to carry out astronomical observations and to map radiation from selected areas of the sky. The telescope optical system consists of a conventional Cassegrain arrangement with an f/2 aluminum primary mirror, spherically figured, which feeds a pyrex secondary mirror to produce an f/13.8 beam at the focal plane with a scale of 15.2 arc sec/mm. Three focal planes are provided. The infrared detectors consist of an array of four gallium-doped germanium bolometers fitted within a two-liter helium dewar. An altitude-azimuth mount design is used for attitude control, with the pointing objectives being achieved in two steps. The azimuth control system is capable of operation in a position mode, in which the sensing element is a servo-driven null magnetometer always pointed north, and in an inertial mode, in which the gyro is uncaged and becomes the azimuth reference. The elevation system also operates in both position and inertial modes. An auxiliary position control, powered by an independent battery and controlled by a separate tone command system, is provided in case of a primary system difficulty.
Document ID
19750032883
Acquisition Source
Legacy CDMS
Document Type
Conference Proceedings
Authors
Hazen, N. L. (Smithsonian Astrophysical Observatory and Harvard College Observatory Cambridge, Mass., United States)
Date Acquired
August 8, 2013
Publication Date
January 1, 1974
Subject Category
Astronomy
Meeting Information
Meeting: Instrumentation in astronomy II; Seminar-in-Depth