1. Now consider a real 2.5m telescope. Assume its CCD camera has both a read noise of 10 counts and a dark current of 10 counts/second for every pixel.
a. The star is observed for 20 seconds and a total of 20,400 counts are recorded from the image and this image is spread over 40 pixels in the CCD camera. What is the S/N of the detection of this star?
b. What is the S/N if the telescope detects a background nebula that contributes a uniform background of 99 counts in each of the 500 pixels that surround the star image?