6: Astronomical Instruments Flashcards
combination of multiple radio dishes to, in effect, work like a large number of two-dish interferometers
interferometer array
(of telescope) point where the rays of light converged by a mirror or lens meet
focus
magnifying lens used to view the image produced by the objective lens or primary mirror of a telescope
eyepiece
light in a telescope is reflected by a small secondary mirror off to one side, where it can be detected
Newtonian focus
concave metal reflector in a radio-reflecting telescope, analogous to a telescope mirror
dish
instrument for collecting visible-light or other electromagnetic radiation to observe distant objects
telescope
unsteadiness of Earth’s atmosphere, which blurs telescopic images; good seeing means the atmosphere is steady
seeing
device sensitive to electromagnetic radiation that makes a record of astronomical observations
detector
distortion that causes an image to appear fuzzy when each wavelength coming into a transparent material focuses at a different spot
chromatic abberation
process in which waves mix together such that their crests and troughs can alternately reinforce and cancel one another
interference
length of time that a lens collects light before creating an image
integration time
technique of transmitting radio waves to an object and then detecting the radiation that the object reflects back to the transmitter; used to measure the distance to, and motion of, a target object or to form images of it
radar
systems used with telescopes that can compensate for distortions in an image introduced by the atmosphere, thus resulting in sharper images
adaptive optics
array of high-sensitivity electronic detectors of electromagnetic radiation, used at the focus of a telescope (or camera lens) to record an image or spectrum
charge-coupled device (CCD)
telescope in which the principal light collector is a concave mirror
reflecting telescope
light in a telescope is reflected by the secondary mirror down through a hole in the primary mirror to an observing station below the telescope - used in most professional telescopes
Cassegrain focus
diameter of the primary lens or mirror of a telescope
aperture
telescope in which the principal light collector is a lens or system of lenses
refracting telescope
transparent piece of material that bends the rays of light passing through it
lens
point in a telescope where the objective lens or primary mirror focuses the light
prime focus
modern technology that measures sag on a telescope mirror and applies force to its back to correct it
active control
piece of material with thousands of grooves on its surface that spreads light out into a spectrum
grating
detail in an image; specifically, the smallest angular (or linear) features that can be distinguished
resolution
distance from the lens to the location where the light rays focus behind the lens (image)
focal length
instrument that combines electromagnetic radiation from one or more telescopes to obtain a resolution equivalent to what would be obtained with a single telescope with a diameter equal to the baseline separating the individual separate telescopes
interferometer
