Ephemeris Date Range
The date range settings are the block of five fields below the basic settings on every study editor: Start Date, Start Time, End Date, Interval, and Time Unit. Together they define the period the study covers and how finely it is sampled.
Every field already shows its current value, taken from the workspace defaults when the study was created, so you change only the settings you want to adjust:
- Study period: the Start Date, Start Time, and End Date fields bound the span of time the study covers.
- Sampling rate: the Interval field and the Time Unit dropdown decide how often within that span a record is sampled.
You type the dates and times into masked pickers; there is no calendar overlay to pick them from. The Interval field accepts positive whole numbers only.
All five fields are disabled once a completed generation locks the study. To change them, unlock the study first.
How the Interval Works
The Interval number and the Time Unit are read together. An Interval of 1 with a Time Unit of Days produces one record per day across the whole span, which is what most ephemerides are built on. An Interval of 6 with a Time Unit of Hours produces four records a day; an Interval of 1 with a Time Unit of Months produces one record a month.
The available time units are:
- Seconds
- Minutes
- Hours
- Days
- Months
- Years
The interval and the span together decide how many records the study produces, and therefore how long the generation takes. A century at one record per day is roughly 36,500 records. Check the Record Count after generating to confirm you got the volume you expected.
Time Zones
The dates and the time of day are interpreted in the time zone of the location chosen in the Basic Ephemeris Settings, so set the location before you set the range. Generated records are dated in that same time zone.