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Finding HT Cas's Diameter using Radar Pulses

Radio Telescope

Radar pulse method

Your experiment will use the same basic principle that dolphins and bats use to locate objects. You will send two probes to HT Cas - one to its pole, one to the equator. They have synchronized clocks, and they will release a flash of light in all directions at the same moment. The light from the probe at the pole will have travelled a distance R greater than the light from the equator. By measuring the time lag of the arrivals of the two signals from HT Cas, you will be able to calculate the size of the star.

diameter = 2 x R = 2 x ct

c = 3 x 108 m/sec
t = time lag between signals

diagram of pulse pattern off HT Cas

You have wisely chosen to use radio waves for your probe signal, since they are not absorbed by the Interstellar Medium. However, before applying for funds to launch this experiment, you want to check the feasibility of success of this approach.

Calculate Calculate how much signal would return to Earth.
Calculate Calculate how long it would take to receive the return signal from HT Cas.

A service of the High Energy Astrophysics Science Archive Research Center (HEASARC), Dr. Alan Smale (Director), within the Astrophysics Science Division (ASD) at NASA/GSFC

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