Just what
DOES an astronomer do?
•All
observational astronomy is basically a matter of recording
photons, be they visible, infrared, gamma rays, or
radio.
•It all reduces
to one of two things:
–Seeing
how the photons are distributed over a two-dimensional
space (taking an image), or...
–Measuring
how many photons arrive per unit of time (taking
photometry).
•It does not
matter if your detector is your eye, a CCD, or a heterodyne
receiver; you still are counting photons.
