Dasha and transit (gochar): how they work together
Dasha and transit (gochar) are two separate timing tools. The dasha is a fixed planetary period from birth, while transit is the Moon's and other grahas' current position against the natal chart.
What it is
Traditional readings often combine them: a graha's transit through a sign is read in light of the dasha that is running. The combination is a matter of school and practice rather than a fixed rule in the standard texts.
How it is worked out or read
This site computes the dasha from birth and the transit positions separately. It does not combine them into a result.
Where it appears on this site
The dasha is in the dasha tool. Saturn's transit is used in the chart checks for Sade Sati.
Two different clocks
A dasha is a fixed clock set by the birth chart, while a transit is a moving clock set by the sky. The dasha runs from birth in a predictable sequence, and its boundaries are known in advance. The transit changes as the grahas move, and it is read against the natal chart at the moment in question. Because they run at different speeds and from different references, the two are often considered together rather than one replacing the other.
The reader who wants to compare them should first establish the dasha period and then look at the transits during that period. The dasha says which theme is in the foreground, and the transits say where the moving grahas are relative to the natal chart at the time.
How traditional readers combine them
Many traditional readers look at the transit of a slow graha during a particular dasha. For example, Saturn's transit through a sign counted from the natal Moon may be read differently when the Saturn dasha is running, or when the Moon's own dasha is active. These combinations are part of the practice of many schools, but they are not fixed rules in all the classical texts, and the reader should check the source for each combination.
The combination is a matter of judgement and tradition. A reader who uses it should state which transit and which dasha are being considered, so that the reading can be checked by someone else.
What the site does with them
This site computes the dasha timeline from the birth data and computes Saturn's sign for the Sade Sati check. It does not combine the two into a single reading. The user can see both and decide how to weigh them. This keeps the calculations separate and checkable, and the interpretation is left to the reader and to any practitioner the reader consults.
A worked comparison
Suppose a person is in a Jupiter mahadasha, and Saturn is transiting a sign counted from the natal Moon that falls in the twelfth position. A traditional reader would note both factors: the expansive Jupiter period, and the restraining Saturn transit. The reading would say that the period brings growth alongside a need for patience and reassessment, and it would note that the emphasis depends on the chart's other features. This is a common kind of combined reading, and it is most useful when each factor is described on its own first.
The same reader would also check the dates. Saturn's transit lasts about two and a half years in each sign, while the Jupiter period may last many years, so the combined reading has a shifting character as Saturn moves on.