Heliacal Phases
This calculation module is designed to determine the exact dates of heliacal phases (moments of visibility and invisibility) of planets and fixed stars within a specified time range for a specific geographical latitude.
What are heliacal phases?
During its annual motion, the Sun moves among the stars from west to east. Because of this, luminaries (stars or planets) periodically end up too close to the Sun in the daytime sky, getting lost in its rays (the period of invisibility or “combustion”).
- Heliacal rising is the first rising of a celestial body immediately before sunrise (rising in the rays of the morning dawn) after a period of invisibility. From this day on, the luminary becomes available for visual observation again.
- Heliacal setting is the last day before a period of invisibility when the luminary can still be seen in the evening sky after sunset. Important: the dates these phases occur heavily depend on the observer’s geographical latitude, so the program takes into account the location specified at the top of the window.
Calculation Settings
In the right part of the panel, you can set the necessary parameters:
- Time Range: Set the start date and the duration of the search (in years and days).
- Objects: A block of checkboxes to quickly select the planets (from Moon to Pluto) whose phases you want to calculate.
- Stars: If you activate this option, you can load a star catalog file (via the “Choose file…” button) to calculate their heliacal risings and settings.
Reading the Results Table
After calculation, a list is generated where one of four possible phases is recorded for each object:
- Morning rising (Heliacal rising).
- Morning setting (start of invisibility in the morning sky).
- Evening rising (emerging from the Sun’s rays in the evening sky).
- Evening setting (Heliacal setting). The table displays the object’s symbol, the name of the phase that has occurred, and the exact date/time of the event.
Context Menu
By right-clicking any row in the table, you can:
- Apply to dial (1-4): Rebuild the selected working chart dial to the exact date and time of the calculated phase.
- Save to TXT: Export the calculated list of events to a simple text file.