1. Enter birth date and time
Use the local date and time shown on the birth record. Astro Legacy interprets a time without an explicit offset in the timezone of the selected location and converts it to UTC for calculation. If you do not know the time, select the unknown-time option; the app uses 12:00 and warns that houses and angles are approximate.
2. Choose the birth location
Search for a city or select a point on the map. The coordinates determine the local timezone and are required for house cusps and chart angles. Two places sharing a city name can be in different regions, so check the country and displayed location before calculating.
3. Select a house system
Placidus is the default. Astro Legacy also offers Krusinski, Koch, Equal, Whole Sign, Regiomontanus, Campanus and Porphyry. Changing the system can move house cusps and the house assigned to a planet without changing that planet’s zodiac longitude.
Use house systems and birth time when comparing methods.
4. Set the analysis horizon
The horizon defines how far ahead Astro Legacy searches for transit activity and exact aspects. A short range is easier to scan; a longer range is better for locating slower cycles. A longer horizon can require more calculation and should not be read as one continuous prediction.
5. Run the analysis
Select Analyze transits. The backend validates the request, resolves local time, calculates or reuses the natal chart and asks the ephemeris engine for current and future positions. It then classifies aspects, phases, exact dates and relative intensity.
6. Read the chart and tables
The wheel combines the natal chart with transiting positions. The tables organize active transits by period. Select a row to highlight the relationship on the chart and open its details.
Read fields in this order:
- transiting planet and natal target;
- aspect and orb;
- applying or separating phase;
- exact date and active window;
- natal and transit houses;
- retrograde status and relative intensity.
The four natal angles ASC, DESC, MC and IC can appear as valid transit targets. They are not planets and do not have a meaningful natal retrograde state.
7. Focus with filters
Use minimum intensity to reduce the number of visible rows and the planet filter to isolate a cycle. Filters do not change the calculation; they change what is displayed. The chart-axis toggle simplifies the wheel without removing axes from the underlying natal data.
Keeping your work while reading
After a successful calculation, Astro Legacy saves the current request, result and main display settings in this browser tab for up to two hours. Open a guide and use Return to your analysis to restore the view. The temporary session is not stored in a cookie and is not sent with normal page requests.
If you enable Remember my data, birth form fields can additionally remain in this browser for up to one year. Use Reset analysis to remove only the result, or Clear saved data to remove the stored form as well.
Tips for dependable results
- Verify the birth location and timezone.
- Use the most accurate birth time available.
- Treat noon-time houses and angles as approximate.
- Start with a moderate horizon and narrow it when a cycle looks relevant.
- Compare exact dates and repeated passes before interpreting a transit in isolation.
- Use the result for reflection, not as the sole basis for an important decision.
Common questions
Does Astro Legacy require an account?
No. The web calculator runs without registration.
Does opening a guide erase my result?
No. A successful analysis is kept temporarily in sessionStorage for the current tab. It expires automatically and can be reset manually.
Does the interpretation come from the same system as the calculation?
The ephemeris and backend calculate the technical result. Optional plain-language explanations use that calculated context and a stored explanation workflow; they do not recalculate planetary positions.
Why are there different time ranges?
They make the result scannable. A fast, near-term transit and a slow multi-month cycle need different presentation, even though both come from the same analysis.