IAU Commission 41 (History of Astronomy) was founded in 1948, and between 1991 and its termination in 2015 this Commission hosted seven different Working Groups (one of which was shared with Commission 40 (Radio Astronomy). In this paper we list the objectives of these seven Working Groups and track their progress. We conclude by evaluating the role that each C41 Working Group played in furthering research on the history of astronomy.

Ocean Drilling Program (ODP) Site 677 provided excellent material for high resolution stable isotope analysis of both benthonic and planktonic foraminifera through the entire Pleistocene and upper Pliocene. The oxygen isotope record is readily correlated with the SPECMAP stack (Imbrie et al. 1984) and with the record from DSDP 607 (Ruddiman et al. 1986) but a significantly better match with orbital models is obtained by departing from the timescale proposed by these authors below Stage 16 (620 000 years). It is the stronger contribution from the precession signal in the record from ODP Site 677 that provides the basis for the revised timescale. Our proposed modification to the timescale would imply that the currently adopted radiometric dates for the Matuyama–Brunhes boundary, the Jaramillo and Olduvai Subchrons and the Gauss–Matuyama boundary underestimate their true astronomical ages by between 5 and 7%.