British astronomer (born 1942) who identified the first stellar black hole in our galaxy, a star called Cygnus X-1. Two items: an original ballpoint sketch of the interaction between the blue supergiant variable star designated HDE 226868 and the Cygnus X-1 black hole on a white 8 x 5 sheet, signed below by Murdin, who adds a brief note: "I saw the effect of Cygnus X-1 on the star HDE 226868 and was able to infer the existence of the black hole in Cygnus X-1. Paul G. Murdin"; and an ALS, signed "Paul," one page, 5.75 x 8.25, July 27, 2016, in full: "My reply to your letter is late but your letter was much delayed in getting to me. I hope the enclosed meets your needs." In overall fine condition.
