Space Cover #130, Palomar Mountain
Most of the time astrophilatelic collecting is thought of in terms of "space programs" of various countries including rockets and satellites but the basis of these programs is the study of "space." A side collection to these space programs is stamps and covers related to astronomy or the study of celestial objects... many telescope satellites have been launched to study to this field such as the Orbiting Astronomy Observatory or OAO satellite series, the Hubble telescope and the under development Hubble replacement the James Webb Space Telescope.
Prior to experiments being flown aboard stratospheric balloons, satellites and sounding rockets the main way of gathering data was through the use of optical telescopes. The best known of these is the Hale Telescope — a project started in 1928 to create the largest optical telescope in the world with a 200 inch diameter mirror. The observatory would be located in the Palomar Mountain Range in California. The dedication of the Hale Telescope at Palomar Observatory took place on June 3, 1948 and was commemorated by a United States stamp on August 30, 1948 from the city of Palomar Mountain. There are many different FDCs for this stamp in both machine and hand cancels.
There are several other telescopes located on the grounds. One of these is the Schmidt Telescope (since 1986 it has been known as the Samuel Oschin Telescope or the Oschin Schmidt Telescope). This telescope is strictly a camera — no eyepiece to look through — with a 48 inch aperture Schmidt camera. Construction began on the Schmidt telescope began in 1939 and completed in 1948.
The event covers pictured above commemorate some of the initial discoveries by the 48 inch Schmidt telescope. The first postmarked on July 23, 1949 commemorates the discovery of Planatiod "X" which is considered the first important discovery of this observatory. Note that the correct spelling should be "Planetoid" instead of "Planatoid" - a planetoid is a "large" minor planet.
The second is postmarked on July 30, 1949 and was created to document the use of the Schmidt telescope to create a Complete Atlas Map of Celestial Objects up to 300 million years distant.
The address on the back of this cover is for the Historic Aeronautics Assn., 545 Palm Avenue, Burbank, California. The Historic Aeronautics Assn. created a number of classic early space covers including one for the launch of the V-2 rocket from the USS Midway in September 1947.
So if you are interested in "space" you should consider adding some astronomy covers to your collection.