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:
“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)
“In going where you have to go, and doing what you have to do, and seeing what you have to see, you dull and blunt the instrument you write with. But I would rather have it bent and dulled and know I had to put it on the grindstone again and hammer it into shape and put a whetstone to it, and know that I had something to write about, than to have it bright and shining and nothing to say, or smooth and well oiled in the closet, but unused.”
—Ernest Hemingway (1899–1961)
“Since body and soul are radically different from one another and belong to different worlds, the destruction of the body cannot mean the destruction of the soul, any more than a musical composition can be destroyed when the instrument is destroyed.”
—Oscar Cullman. Immortality of the Soul or Resurrection of the Dead? The Witness of the New Testament, ch. 1, Epworth Press (1958)