Another set of old data, this time of the ET or Owl Cluster in Cassiopeia, sometimes known here as the Chicken Cluster. Taken with the M25C in my old William 98. The exposure was 20x60sec, calibrated with a Masterflat and stacked by average in Astroart. Finally processed in Photoshop CS6. NGC457 is in the middle, and to the upper right is a smaller cluster NGC436. Both were discovered by Herschel, when light pollution was unknown but telescope mirrors were made of Speculum metal reflected only some 66% of the light they received, so in his early days when he used a diagonal, he'd get only 30-odd% of the light, and that only while the mirrors were new and untarnished, which they did quite quickly.

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