Instrument
A zenith camera combines an optical lens (about 10-20 cm aperture) with a digital image sensor (CCD) in order to image stars near the zenith. Electronic levels (tilt sensors) serve as a means to point the lens towards zenith. Zenith cameras are generally mounted on a turnable platform to allow star images to be taken in two camera directions (two-face-measurement). Because zenith cameras are usually designed as non-tracking and non-scanning instruments, exposure times are kept short, at the order of few 0.1 s, yielding rather circular star images. Exposure epochs are mostly recorded by means of the timing-capability of GPS-receivers (time-tagging).
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Famous quotes containing the word instrument:
“The law is not a “light” for you or any man to see by; the law is not an instrument of any kind. The law is a causeway upon which so long as he keeps to it a citizen may walk safely.”
—Robert Bolt (1924–1995)
“Reason is man’s faculty for grasping the world by thought, in contradiction to intelligence, which is man’s ability to manipulate the world with the help of thought. Reason is man’s instrument for arriving at the truth, intelligence is man’s instrument for manipulating the world more successfully; the former is essentially human, the latter belongs to the animal part of man.”
—Erich Fromm (1900–1980)
“We ought, says Kant, to become acquainted with the instrument, before we undertake the work for which it is to be employed; for if the instrument be insufficient, all our trouble will be spent in vain. The plausibility of this suggestion has won for it general assent and admiration.... But the examination can be only carried out by an act of knowledge. To examine this so-called instrument is the same as to know it.”
—Georg Wilhelm Friedrich Hegel (1770–1831)