Question: what is the meaning of “Time on source”? I noticed that lower RMS noise demands longer “Time on source”. I would appreciate getting explanation about the connection between them. — Daniel
Answer: The time on source is the amount of time that one spends integrating the signal from a particular direction in space. As one accumulates on-source measurements, the root-mean-square noise of those measurements goes down. If the individual measurements are independent, then that noise decreases by the square-root of the amount of time spent integrating on-source.