Rank 89 documents the Compton Gamma Ray Observatory — the 17,000 kg Great Observatory that mapped cosmic gamma radiation from 20 keV to 30 GeV after Space Shuttle Atlantis deployed it from STS-37 on 7 April 1991. CGRO carried four instruments — BATSE, OSSE, COMPTEL, and EGRET — that defined gamma-ray burst statistics, discovered the Geminga gamma-ray pulsar, and charted the diffuse cosmic background. Alan Bunner managed the program; Neil Gehrels led BATSE science that catalogued approximately 2,700 GRBs and established their isotropic sky distribution. After a gyro failure in 2000, NASA deliberately deorbited Compton on 4 June 2000 over the Pacific — the only Great Observatory not still operating, sacrificed to protect public safety. Wallimilist renders the Atlantis deploy hero, COMPTEL/EGRET labels, vertical COMPTON GRO spine, and diffuse gamma sky stipple exactly as the master PNG dictates — 1991 Great Observatories kicker and curator copy on CGRO legacy.