Module: AstroChart::TimeConversion

Defined in:
lib/astro_chart/time_conversion.rb

Class Method Summary collapse

Class Method Details

.to_julian_day(birth_date, birth_time, timezone) ⇒ Object

Convert a local date/time + timezone to Julian Day.

birth_date: “YYYY-MM-DD” birth_time: “HH:MM” timezone: IANA timezone string, e.g. “Asia/Taipei”



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# File 'lib/astro_chart/time_conversion.rb', line 10

def self.to_julian_day(birth_date, birth_time, timezone)
  tz = TZInfo::Timezone.get(timezone)

  parts = birth_date.split("-").map(&:to_i)
  year, month, day = parts

  time_parts = birth_time.split(":").map(&:to_i)
  hour, minute = time_parts

  # Build local time and convert to UTC
  local_time = Time.new(year, month, day, hour, minute, 0, tz.observed_utc_offset)

  # TZInfo gives us the proper UTC offset; convert to UTC
  utc_time = tz.local_to_utc(Time.new(year, month, day, hour, minute, 0))

  ut_hour = utc_time.hour + utc_time.min / 60.0

  Ephemeris.julday(utc_time.year, utc_time.month, utc_time.day, ut_hour)
end