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In
order for UW undergraduates to gain experience with interferometry the
junior members of the ObsCosLab began a project to build three Small
Radio Telescopes (SRTs) to map the neutral Hydrogen of the Milky Way.
| 21 cm Emission Lines |
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Neutral Hydrogen consists of one
proton and one electron. When the spins of the particles are aligned
the atom has a slightly higher energy than when the spins are opposite.
When an electron in the lowest orbital changes from spin aligned to
misaligned the energy of the atom decreases by a small energy E. In
order to conserve energy, the a photon must be emitted with frequency
f=E/h=1420MHz, corresponding to a wavelenght of 21cm. Our radio
telescopes are designed to be sensitive to a small band of frequencies
centered at 1420MHz.
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Unlike a single telescope, an interferometer combines the signals from
an array of telescopes to obtain measurements with much higher
resolution. A typical interferometer, a "multiplying interferometer,"
nominally consists of receivers, pre-amplifiers, and a correlator that
multiplies the signals together.
We
Used the Documentation and Program from MIT Haystack, MA. Their webpage
is http://www.haystack.mit.edu/
and the srt page is http://www.haystack.mit.edu/edu/undergrad/srt/index.html
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