Tuesday 27 June 2023

Double stars seen through a Cooke telescope in Canada

 In 1892 Dr J C Donaldson of Fergus who had been testing the excellence of his 3.5 inch Cooke by ascertaining the smallest aperture with which he can see certain well known doubles.

On the night of October 9th he was able tom see the companion of Polaris with his glass stopped down to an aperture of 1.8 inches.

With the same aperture on the 12th December, he saw the companion of Rigel and the 4 stars of theta Orion, and with the 2 inch Cooke glass, the 6 stars in the multiple stars sigma Orion

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