## needs to run after paste()
.leap.seconds <- local({
    .leap.seconds <-
        c("1972-6-30", "1972-12-31", "1973-12-31", "1974-12-31",
          "1975-12-31", "1976-12-31", "1977-12-31", "1978-12-31",
          "1979-12-31", "1981-6-30", "1982-6-30", "1983-6-30",
          "1985-6-30", "1987-12-31", "1989-12-31", "1990-12-31",
          "1992-6-30", "1993-6-30", "1994-6-30","1995-12-31",
          "1997-6-30", "1998-12-31", "2005-12-31")
    .leap.seconds <- strptime(paste(.leap.seconds , "23:59:60"),
                              "%Y-%m-%d %H:%M:%S")
    c(as.POSIXct(.leap.seconds, "GMT")) # lose the timezone
})