“2016年IOAA理论第5题-穿过GMRT波束”的版本间的差异
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==英文题目== | ==英文题目== | ||
'''(T5) GMRT beam transit''' | '''(T5) GMRT beam transit''' | ||
2019年9月11日 (三) 17:45的版本
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英文题目
(T5) GMRT beam transit
Giant Metrewave Radio Telescope (GMRT), one of the world's largest radio telescopes at metre wavelengths, is located in western India (latitude: 19°6′ N, longitude: 74°3′ E). GMRT consists of 30 dish antennas, each with a diameter of 45.0 m. A single dish of GMRT was held fixed with its axis pointing at a zenith angle of 39°42′ along the northern meridian such that a radio point source would pass along a diameter of the beam, when it is transiting the meridian.
What is the duration 𝑇transit for which this source would be within the FWHM (full width at half maximum) of the beam of a single GMRT dish observing at 200 MHz?
Hint: The FWHM size of the beam of a radio dish operating at a given frequency corresponds to the angular resolution of the dish. Assume uniform illumination.
