Apollo 17 CDR reports distant flashing rotating object — translunar coast

Apollo 17 Commander Cernan observed a bright, distant object exhibiting a rhythmic two-phase flash pattern (one bright flash followed by one dim flash) at approximately 45 degrees elevation above the spacecraft's XZ plane. Houston attempted to triangulate the object using spacecraft attitude data. LMP Schmitt and CMP Evans also observed it, and Schmitt proposed it was the spent S-IVB stage viewed end-on and broadside alternately, which was corroborated by subsequent observation.

“"It is a bright object, and it's obviously rotating because it's flashing...the flashes come around almost on time. And it's as we look back at the Earth, it's up at about 11:00 about - oh, maybe 10 or 12 Earth diameters... there is something out there." / LMP: "That's the side and - of the S-IVB - and then the engine bell, Gene."”

OCR is good quality. The object was ultimately attributed by LMP Schmitt to the S-IVB stage tumbling and presenting alternately its broadside and engine bell, consistent with a two-phase flash. Houston was engaged in active triangulation. Mission elapsed time approximately 02:18:48–02:18:56. Resolved as probable S-IVB, not anomalous.