PRS Hand Cancel Variations
Until recently the only variations in PRS hand cancels that were widely recognised were the obvious ones such the USS Iwo Jima for Apollo 13 (position of the ship's name at the top or bottom of the postmark) or the USS Hornet for Apollo 12 (position of the time slug below or above the year or missing). However, David Ball1 introduced a large number of other variations in his book 'American Astrophilately - The First 50 Years'. In this article I will illustrate those that are repeatable. It needs to be noted that hand cancels in particular show a significant natural variation due to the method of application, the envelope paper, storage conditions over the years and other factors. Thus apparent variations that are not repeatable, especially variations in ink density and distribution, are to be expected and can be ignored.
1) American Astrophilately : The First 50 Years, David S. Ball, A&A Publishers LLC (2010)