The Post Office Department released the Palomar Mountain Observatory stamp on August 30, 1948. The observatory is located within the Cleveland National Forest on Palomar Mountain in north San Diego County, California. The stamp appeared during the time that most commemorative stamps were issued because of resolutions of the US House of Representatives and the US Senate. In this case, Congressman Charles K. Fletcher of California introduced House Resolution 6368 "to provide for the issuance of a special postage stamp in commemoration of the dedication of Palomar Mountain Observatory." Senator Sheridan Downey of California introduced a similar resolution in the Senate, Sen. Res. 2616. After both passed, President Truman signed the act into law on June 21, 1948.
Clark Helms described the observatory as "one of the world's greatest scientific marvels, an instrument that possessed 360,000 times the light-gathering power of the unaided human eye, a device capable of penetrating into two billion light years of space." Originally called the Hale Observatory to honor solar astronomer George Ellery Hale (1868-1938), the observatory is now known as "Palomar," meaning "pigeon roost" in Spanish, from the mountaintop it sits upon.
Victor S. McCloskey, Jr., designed the stamp. He referred to a photograph that features an exterior view of the observatory. The California Institute of Technology, which operated the observatory jointly with the Carnegie Institution of Washington, had sent the Post Office Department a selection of photographs from which McCloskey could choose. G.A. Gunderrsen engraved the vignette; E.H.Helmuth engraved the frame, the lettering, and the numerals.
- Bureau Specialist. West Somerville, Massachusetts: Bureau Issues Association, Inc. (February 1949), 25.
- First Days. Brick, New Jersey: American First Day Cover Society. (September 1, 1987), 726.
- Mekeel's Weekly Stamp News. Portland, Maine: Severn-Wylie-Jewett Company. (June 30, 1947), 599.
- Western Stamp Collector. Mill City, Oregon. (May 6, 1948).
Steven J. Rod