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Variable stars in Messier 3. At least 270 variable stars have been discovered in M3, more than in any other globular cluster. Many of them increase and decrease in brightness over a period of a few hours, so variations in brightness can be seen on a single night or from one night to the next. Jim Mazur took 3 images of M3 about an hour apart on one night in May, then 4 more on the next clear night. The animation loop below includes these 7 images. Watch carefully you can see many variable stars blinking. At least 40 variable stars show up in this sequence. The pictures were taken with a Meade 14-inch telescope and and SBIG STF-8300M camera. The dense core of the cluster appears to vary in brightness but this is because it was hard to match the 7 images perfectly. What you should look for is stars that appear to twinkle even though other nearby stars appear constant.

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