A light-minute is the distance light travels in a vacuum in one minute's time. The distance of a light-minute is 11,176,943.8 miles or 17,987,547.5 km
You can take half of the rate of variability and measure it against lightyears to get the maximum distance.It means that if it takes half a minute to complete the full brightness,the source cannot be brigger than half a lightminute across
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