This 8-3/4″ diameter star chart consists of a black star disc below and a semitransparent rotating disc. The rings on the outer disc signify what stars would be seen through the LM Optical Telescope at certain times during the stay on the moon.
Star charts like this were used on every lunar landing mission to orient the LM just prior to liftoff. The star chart is dated for a launch date of 11 April 1970 (Apollo 13), and was to be used in case the Lunar Module had to leave the moon’s surface within 2 hours after landing (TD+2 means Touchdown + 2 Hours).
Each Lunar Module carried two similar star charts – this one for an immediate liftoff, and another for liftoff after the stars had precessed across the sky during their stay on the moon. This star chart was used in the Lunar Module Simulator during the training for Apollo 13.
My friend Larry McGlynn has written an excellent two-part overview of the star charts of Apollo. Links here: Part one and part two.
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