Night of 20210906
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Moore Observatory 
CDK20N

Each file is a 20 second exposure through a Sloan filter
The color image is a composite of the three FITS images rended such that 
the near-infrared Sloan i' filter is red in the displayed image, 
the red Sloan r' is green in the displayed image, and the blue-green Sloan g'
filter is blue in the image.  The result is a representation of star colors from
the visible to the near-infrared which shows the subtle differences in color
that are a consequence of the differences of the surface temperatures of the
stars in the cluster.

These images have north up and astronomical west to the right, as it would
appear in the sky if you were facing south, leaning back to look overhead while
the cluster came into view from the east.

The intensity is on a logarithmic scale to encompass the range of stellar
brightnesses in the cluster. The original images were exposed to avoid
saturation of the brightest stars and consequently the inner regions of M13 are
resolved.  Seeing at the time of these exposures was of the order of 2
arcseconds and was fully resolved by the telescope.