Your Trail and chart
What if I don't know my birth time?
Choose the unknown-time option and FMRX works from midday. Here's what that changes.
Pick "I don't know my birth time" when FMRX asks for your birth details, rather than guessing. The app then builds your chart from midday (12:00) on your birth date, and everything else works as normal.
Why midday
Midday sits in the middle of the day, so whatever time you were actually born, the chart starts from a point that is never more than twelve hours away from it. That's the smallest possible error when the real time is unknown. A guessed time can land much further off, and you won't know it.
What it affects
Your birth time sets where the Moon was when you were born, and the Moon's position is what starts the clock on your dasha periods, the time periods your Trails are cut from. With a midday chart the periods are still real and still yours, but where one Trail ends and the next begins can sit a little off from where an exact birth time would put it.
Your rising sign isn't shown. It changes roughly every two hours, so a rising sign worked out from midday would probably be wrong, and we'd rather leave it out than present a guess as a fact. The journal, your Zones, Steps and Markers are unaffected.
If you learn your birth time later
Update your birth details from Settings (Me tab, then the gear icon). Your chart is recalculated from the new details. Changes are limited: a free account can change its birth details once; paid plans get three changes, then a 30-day wait between any further ones. Change them when you're sure rather than experimenting. A birth certificate or hospital record is the most reliable source.