1. A 2.5m aperture telescope obverses a star through an R filter. Assume that there is no noise associated with the detection system. The CCD has a full well depth of 20,000 counts and a gain correction factor of 1.00000.

a. On average, the telescope detects 3 photons/sec from this star. What is the probability that it will detect less than three photons in an 1 second observation

a. On average, the telescope detects 3 photons/sec from this star. What is the probability that it will detect less than three photons in an 1 second observation

I’m pretty sure I got this one, use the Poisson distribution as shown below.

P = (3^0e^(-3))/0! + (3^1e^(-3))/1! + (3^2e^(-3))/2! = 0.42

b. Another star is observed. On average, the telescope detects 1,230 photons/sec from this star. What is the probability that will detect more than 1,230 photons in any one second observation?

It is this part I am a little unsure of, I know I need to use the normal distribution but not sure how to reach from it.

Thanks in advance

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