Ephemeris Study

Generate a custom tabular ephemeris of planetary positions for the bodies, period and interval you choose. Create an Ephemeris study, set its location, Reference System, date range and interval, check the bodies and metrics to include, then click Run and read the results in the ephemeris table.

An Ephemeris study samples the positions of the selected bodies at a fixed interval across a date range. The positions are measured from the study's coordinate origin: Geocentric, Topocentric or Heliocentric. Each sample becomes one record, shown as one row of the Ephemeris Table.

Study Layout

When you click an Ephemeris study in the Studies List, its view fills the study area. The settings column on the left holds, from top to bottom:

• Study Name: the name the study has in the Studies list. See Study Name.
• The Location, Zodiac, Coord. Origin and Ref. Plane settings. See Location and Reference System.
• The Start Date, Start Time, End Date, Interval and Time Unit settings. See Date Range and Interval.
• The Bodies and Metrics lists, side by side. See Bodies List and Body Metrics List.

The results area on the right holds the ephemeris table, the record count beneath it (see Record and Point Count), and a button bar:

Button	Description
Run	Generates the study's records. See Generate Study.
Cancel	Stops a generation in progress. See Cancel Study Generation.
Find	Jumps to the record nearest a chosen date. See Find a Record by Date.
Export	Saves the records in CSV format. See Export Records to CSV.
Unlock	Deletes the records and makes the study's settings editable again. See Unlock Study.

What Each Record Holds

Each record holds its date and time and, for every selected body, the metrics checked in the Metrics list: Longitude (or Right Asc), Sign Position, Latitude (or Declination), Distance in AU and Speed in degrees per day. A new Ephemeris study shows Sign Position only.

• The date and time of each record are given in the time zone of the study's location. This is why every study needs a location, whatever its coordinate origin.
• Under the Equatorial reference plane, Longitude and Latitude read Right Asc and Declination, and Sign Position is unavailable.
• There are two ways to choose which columns the ephemeris table shows: check or uncheck metrics in the Metrics list, or right-click any column heading and use the Column Visibility Menu.
• You can reorder the columns (see Reorder Record Columns), but the Date Time column always stays first. The table cannot be sorted: clicking a column heading does not sort the rows.

Generate an Ephemeris Study

Create the study with Ephemerides → Ephemeris on the menu bar, or with the Ephemeris button on the toolbar: see Create Study. The Ephemeris button is the first of the four study-type buttons and shows an icon only: the same icon as an Ephemeris study in the Studies list and, on Windows, as Ephemeris in the Ephemerides menu. The new study, named "Ephemeris", appears selected at the bottom of the Studies list, and its settings already hold the workspace defaults.

Change the location, Reference System, date range or interval only where this study needs other values: see Location and Reference System and Date Range and Interval. Most ephemerides use an interval of 1 day.

The Bodies list of a new Ephemeris study already has the bodies of the default preset checked: the Mercury -> Pluto preset, unless you have marked another preset as the default (see Bodies List Presets).

To choose the bodies and metrics and generate the records:

1. Check the bodies to include in the Bodies list, and uncheck any you want to leave out.
2. Check the metrics to show in the Metrics list.
3. Click Run in the button bar below the ephemeris table.

The study locks while it generates, and a progress bar beside the Cancel button shows the percentage complete. When generation finishes, the records appear in the ephemeris table, the record count appears beneath it, and the Run button disappears until you unlock the study.

tip

You can check or uncheck metrics in the Metrics list after the study is generated: the table's columns change at once, without generating the study again.

Work with the Records

Once the study is generated, you can:

• Find a Record by Date: jump to the record nearest a chosen date.
• Copy Records to the Clipboard: copy a date or a block of records into another document or spreadsheet.
• Drag Records into Another Application: move records straight into a spreadsheet.
• Export Records to CSV: save every record with the visible columns in their displayed order.
• Open a Record's Chart in Compass: double-click a record row to see its chart in the companion application Compass.

To change the settings or the bodies and generate the study again, unlock it first. Unlocking deletes the records: see Unlock Study.

Related Topics

• Create Study: add a new study of any type to the workspace.
• Generate Study: produce the records of a configured study and follow its progress.
• Aspect Ephemeris Study: record the angular relationships between pairs of bodies alongside their positions.
• Graphic Ephemeris Study: plot the positions of the bodies as curves on a graph.
• Default Settings Editor: set the defaults new studies start with.