R/prepare_datetime.R

In earthtide: Parallel Implementation of 'ETERNA 3.40' for Prediction and Analysis of Earth Tides

.prepare_datetime <- function(utc, eop = NULL) {
  # set the earth orientation parameters
  if (is.data.frame(eop)) {
    if (all(names(dut1) %in% names(eop))) {
      eop <- eop
    } else {
      stop(paste0(
        "eop must have the following column names: ",
        paste0(names(dut1), collapse = ", ")
      ))
    }
  } else {
    eop <- dut1
  }

  utc <- sort(utc)
  mjd <- utc_mod_julian(utc)
  j2000 <- utc_julian_2000(utc)
  ddt_int <- interpolate_dut1(utc, "ddt", eop)
  dut1_int <- interpolate_dut1(utc, "ut1_utc", eop)
  hours <- (as.numeric(utc) %% 86400.0 + dut1_int) / 3600.0
  t_astro <- (j2000 + ddt_int / 3155760000.0) / 10.0


  list(
    utc = utc, mjd = mjd, j2000 = j2000, ddt = ddt_int, dut1 = dut1_int,
    hours = hours, t_astro = t_astro, eop = eop
  )
}