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Time Systems

Astrea provides a comprehensive time handling system built on top of modern C++ chrono facilities. The time module provides date handling, interval management, and Julian date conversions for astronomical applications.

Core Components

Date Class

The Date class provides functionality for handling dates with astronomical precision:

  • Conversion between string representations and Julian dates
  • Support for various date formats using standard strftime/strptime patterns
  • Sidereal time calculations
  • Clock conversions
#include <astro/time/Date.hpp>

// Convert string epoch to Julian date
JulianDate jd = epoch_to_julian_date("2024-01-01 12:00:00", "%Y-%m-%d %H:%M:%S");

// Convert Julian date back to string
std::string dateStr = julian_date_to_epoch(jd, "%Y-%m-%d %H:%M:%S");

Julian Date Clock

Astrea features a custom JulianDateClock implementation that provides:

  • Native Julian date arithmetic
  • Conversion to/from system clocks
  • High-precision time point representation using double precision for fractional days
  • C++20 chrono compatibility
#include <astro/time/JulianDateClock.hpp>

// Julian date time points
JulianDateTime<std::chrono::milliseconds> jdTime;

// Clock conversions
auto systemTime = JulianDateClock::to_system_clock(jdTime);
auto julianTime = JulianDateClock::from_system_clock(systemTime);

Time Intervals

The Interval class represents time spans for propagation analysis. It stores a start time and end time (called propTime in the implementation). You can calculate durations by taking the difference between these times.

#include <astro/time/Interval.hpp>

Time startTime = epoch_to_julian_date("2024-01-01 00:00:00");
Time endTime = epoch_to_julian_date("2024-01-01 01:30:00");

Interval propagationInterval(startTime, endTime);
// Calculate duration between start and end times
Time duration = propagationInterval.propTime - propagationInterval.start;

Integration with mp-units

All time quantities in Astrea are strongly typed using mp-units, providing compile-time dimensional analysis and preventing unit conversion errors. Time durations automatically work with the physical quantity system.