Problem 1: What is an advantage of the infra-red observations in comparison to optical ones? Can optical CCD detectors be used to measure infrared photons?
Problem 2: Can a silicon CCD (forbidden band gap is 2x10-19 J) be used for infra-red (λ=1μm) observations? Assume that 100% of photon energy is given to electrons.
Problem 3: Why cooling of the detector is of crucial importance to the infra-red observations?
Problem 4: A detector has a background level of 2 photons per second. How long should one observe a source with a flux rate of 0.5 photon per second to get a signal to noise ratio equal to 10?