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).
Read more about this topic: Zenith Camera
Famous quotes containing the word instrument:
“I doused the fatal instrument with lightning promptitude, but it was a good seven minutes before the last indignant handkerchief had folded its wings and gone back to its reticule and the last manufactured cough died protestingly away.”
—Margaret Halsey (b. 1910)
“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)
“Prayer is not an old woman’s idle amusement. Properly understood and applied, it is the most potent instrument of action.”
—Mohandas K. Gandhi (1869–1948)