Answer the following about the Square Kilometer Array, or SKA (“S-K-A”), an ambitious international project to build a radio telescope, for 10 points each.
[10m] The SKA will use this spectral feature to study the cosmic dark ages and the epoch of reionization. This spectral feature is created by a transition between hyperfine levels of the 1s (“one-S”) ground state.
ANSWER: 21-centimeter line [or 21 cm line; accept neutral hydrogen line or H I line (“H-one line”); prompt on hydrogen line or H line]
[10e] The SKA will use over 100,000 antennae to meet its requirements for sensitivity and this quantity. This quantity measures the angular distance between objects that a telescope can distinguish.
ANSWER: angular resolution [accept resolving power or minimum resolvable angle]
[10h] Like the Very Large Array, SKA will use this interferometric technique, which is based on the Van Cittert–Zernike (“vahn SIT-ert SAIR-nee-kuh”) theorem. This technique uses an array of paired telescopes to simulate a single telescope with higher resolution.
ANSWER: aperture synthesis [or synthesis imaging or aperture synthesis imaging]
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