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The two 2MASS Cassegrain-focus equatorial-mount reflector telescopes are
identical in construction, and each has a primary mirror diameter
of 1.3 meters. One telescope is located on Mt. Hopkins
in Arizona (left), and the other on Cerro Tololo, along the Andes
mountains in Chile (facility seen at right).
Each telescope was equipped with a three-channel camera, each
channel consisting of a 256-pixel × 256-pixel detector array,
capable of observing the sky simultaneously at wavelength bands centered at
wavelengths 1.25 micrometers, 1.65 micrometers, and 2.17 micrometers.
(1 micrometer, abbreviated 1 µm, is one-millionth of a meter in length.)
These bands are colloquially known by astronomers as
"J",
"H", and "K-short" (or
"Ks"). The
refrigerated dewar containing the camera is the brass canister hanging below
the telescope. Computers operated each telescope's motion with respect to
the sky; the motion of the much-smaller secondary mirror (seen near the top of
the telescope); and the dark shutters of the three channels and digital
"readout" of the three detector arrays.
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