Depicting the Palomar Observatory located in the Palomar Mountain Range near San Diego, California. The observatory is owned and operated by the California Institute of Technology. At the time of its dedication in 1948, it housed the largest telescope in the world at the time, the Hale Telescope. Plain envelope featuring a single 3-cent Scott 966 stamp, with day of issue cancellation, August 30, 1948 and typewriter address. In acceptable condition, with staining from glue along sealed edges.