Progressed Charts

The API can calculate three (3) different types of progressed charts:

1. Secondary Progressions (SP)
2. Tertiary Major Progressions (TP I)
3. Tertiary Minor Progressions (TP II)

Progressed charts are auxiliary charts that require an underlying radix chart.

How Progressions Are Calculated

Secondary Progressions are based on the principal of "a day for a year". Each year past the radix's datetime is valued in days which are then added to the radix datetime to calculate the progression. The API uses a mean solar year value of 365.24219893 days to calculate the number of years that have passed.

Tertiary Major Progressions are based on the principle of "a day for a month". Each lunar month past the radix's datetime is valued in days which are then added to the radix datetime to calculate the progression. The API uses a mean lunar month value of 27.32158218 days to calculate the number of lunar months that have passed.

Tertiary Minor Progressions are based on the principle of "a month for a year". Each year past the radix's datetime is valued in lunar months which are then added to the radix datetime to calculate the progression. The values for a solar year and lunar month listed above are used for these progressions as well.

Endpoints

Secondary Progressed Charts

GET /:env/secondary-progressed-charts/cast

Tertiary Progressed Major Charts

GET /:env/tertiary-progressed-major-charts/cast

Tertiary Progressed Minor Charts

GET /:env/tertiary-progressed-minor-charts/cast

Request Parameters

The following request parameters apply to all of the progressed chart types:

Parameter	Required	Description
*	Yes	Include all required (and any optional) parameters from Radix Charts.
target_datetime	Yes	Gregorian calendar datetime value of the progression. Format as YYYY-MM-DD HH:MM:SS. Supported year range: 1000-9999 CE. This value will be treated as local time based on the value of target_location.
target_location	Yes	The geographic location for the progression. Any Google Maps compatible value is acceptable. This value is typically the same as the radix chart's location.

Importance of Radix Chart Data

Although the calculations for progressed charts will not return any data related to the radix chart, the datetime and location request parameters of the radix event are needed in order to calculate them correctly.

Limitations of Progressions

The target_datetime value cannot occur prior to the radix's datetime value.

Response Data

Response data and error reporting is identical to the Radix Charts Response Data. The difference is only in the value of the root-level type key:

SP

{
    "data": {
        "type": "secondary-progressed",
        "attributes": {
            ...
        }
    }
}

TP I

{
    "data": {
        "type": "tertiary-progressed-major",
        "attributes": {
            ...
        }
    }
}

TP II

{
    "data": {
        "type": "tertiary-progressed-minor",
        "attributes": {
            ...
        }
    }
}