Take a Journey of Discovery with RXTE - Classroom Activity
A light curve is a graph of intensity over time. Such a graph is made by counting the number of photons coming from a source over a period of time. For example, by counting the number of X-rays being emitted by a star every second for an hour, you could generate a light curve from your observations. Your light curve would tell you how bright your source is and the amount of time it remained at that brightness. A graph similar to a light curve can be generated for any physical measurement which is repeated over and over in time. You could count how many people passed in front of you during a ten minute time interval while you sat on a park bench during your lunch hour. You could generate a "light curve" for this as well, but it would have no astronomical value (of course!).