Globular cluster M14

The globular cluster Messier 14 (NGC 6402) in Ophiuchus, shown from a 2-minute red-light exposure (through clouds) with a Tektronix 2048x2048 CCD at the 2.1-meter telescope of Kitt Peak National Observatory by Bill Keel and Lisa Frattare. North is at the top and east to the left, for direct comparison with a chart or eyepiece view. The image has been block-averaged by a factor of two for this presentation (and another factor of two as shown above), which uses a logarithmic intensity transformation to preserve information across a wide dynamic range. The field is 9.1 arcminutes square.

M14 is rich in variable stars, particularly RR Lyrae pulsating stars. This was driven home in a survey by Amelia Wehlau and Norma Froehlich, using 368 photographic plates spanning the interval from 1912-1980.

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Last changes: 7/2003      © 2003