A boundary nobody publishes
Sign boundaries get all the attention because they are the ones printed as date ranges. Inside every sign there are two further boundaries, at ten and at twenty degrees, dividing it into the three decans. They are just as sharp and they move against the calendar in exactly the same way.
Two August happens to land on one of them. At noon across every year from 1930 to 2035 the Sun on this date has stood between roughly nine and a quarter and about ten and a half degrees of Leo, which straddles the ten degree line. Some years the position falls short of it and some years it has already crossed.
Because they are never printed, the decan boundaries produce none of the arguments the sign boundaries do. That does not make them softer. A position is on one side of ten degrees or the other, with nothing in between.
Which side your year falls on
The pattern follows the leap cycle. In and just after a leap year the date arrives slightly earlier against the Sun's motion, so the position sits lower and stays in the first band. By the third year after a leap year the accumulated quarter days have pushed it up, and the Sun has usually crossed ten degrees by noon.
The hour of birth pulls in the same direction. The Sun advances a little under a degree a day, so a birth after midnight sits below the noon figure and one late in the evening above it. In a year where the noon position is close to ten degrees, the time of day genuinely decides the band, which is unusual and worth checking rather than assuming.
What the two bands are read as
The first ten degrees of Leo belong to Saturn under the Chaldean order and the second ten to Jupiter. The older texts treat the Saturn band as the sign's warmth held under a stricter frame, slower to display itself, and the Jupiter band as the same warmth given room, more generous and more inclined to take up space.
Both descriptions are inherited convention rather than anything measured, and neither is better than the other. The point here is simply that the two readings differ, so a page claiming one of them flatly for this date is claiming more than the arithmetic supports.
The sign ruler is unaffected either way. Leo belongs to the Sun regardless of which band the degree falls in, so the question is which second layer sits on top of it.
Settling it, and what stays open
Resolving the band needs only the year, the hour and the birthplace, all of which the widget above accepts. It returns the exact solar degree rather than the range, which puts the position on one side of ten degrees or the other with no ambiguity, and it reports the distance to the nearest sign boundary as well.
Beyond that the date decides nothing. The Moon covers about half a sign in a day and can change sign during it, and the Ascendant runs through the whole zodiac between one midnight and the next, shifting with latitude as it goes. The sign is the settled part, the band is the interesting part, and the rest waits on a birth time.
Questions people ask about this
Which decan is 2 August?
It depends on the year. The noon position runs from about nine and a quarter to roughly ten and a half degrees of Leo across the last century, so some years fall in the first decan and others in the second.
How do I tell which band applies to me?
Enter your year, birth hour and birthplace in the widget above. It returns the exact solar degree, which lands either side of ten degrees and settles the band without guesswork.
Is the sign in doubt as well?
No. The Sun is ten or eleven days into Leo on this date and the nearest sign boundary is weeks away in both directions, so Leo holds in every year and at every hour.
Why does a leap year change the decan?
Because each ordinary year the date arrives about a quarter of a day early against the Sun and the leap day hands that time back. Over the cycle the position swings by more than a degree, which is enough to cross the line.
What is the difference between the two bands?
The Chaldean order assigns the first ten degrees of Leo to Saturn and the second to Jupiter. The tradition reads the first as warmth under restraint and the second as warmth given room.
Does the birth hour matter here?
In a year where the noon position sits very near ten degrees, yes. The Sun moves a little under a degree a day, so a morning birth and a late evening one can fall on opposite sides of the band edge.