1. A ntennas are spaced 1.0 km apart and form a Y-shaped pattern illustrated abo
ID: 2103077 • Letter: 1
Question
1. Antennas are spaced 1.0 km apart and form a Y-shaped pattern illustrated above. Radio pulses from a distant pulsar (a rapidly rotating neutron star) are detected by the dishes: the arrival time of each pulse is recorded using atomic clocks. If the pulsar is located 60 degrees above the horizontal direction parallel to the right branch of the Y, how much time elapses between the arrival of the pulses at adjacent dishes in that branch of the radio telescope array?
2. These antennas can be moved out to form a large Y. The baseline of each branch can be changed from 0.1 km to 35 km. This forms a virtual telescope as large as 35 km in size. The resolution of a telescope is related directly to its size. If a celestial source emitting radio waves at the wavelength of 21 cm, find the best angular resolution of this virtual telescope.
Explanation / Answer
The signals coming in are traveling at the speed of light or 300,000 km/s
as they are coming in at 60degrees above the horizon their horizontal apparent speed is 300,000cos60 =150000 km/s
as the distance along the line of travel is one km we just take the inverse of the speed to find the time needed
1 / 150000= 6.66*10^-6 seconds
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