Topocentric Graphic Ephemeris Study
A topocentric graphic ephemeris study plots positions as they would be observed from a specific point on the Earth's surface as time-series curves. It gives you a visual record of how observed positions change over time from a particular place.
The study settings occupy a column on the left exactly as they do on a tabular ephemeris. The right side is an Ephemeris Graph instead of an ephemeris table.
Create and Generate the Study
To produce a topocentric graphic ephemeris:
- Click Ephemerides → Topocentric Graphic Ephemeris on the menu bar.
- Configure the Basic Ephemeris Settings (Location, Zodiac, Ref. Plane).
- Configure the Ephemeris Date Range (Start Date, Start Time, End Date, Interval, Time Unit).
- Check the bodies you want in the Bodies list and the metrics you want to plot in the Metrics list.
- Click the Run button beneath the graph.
Step 1 is performed on the Ephemerides menu:
An Interval of 1 with a Time Unit of Days gives one plotted sample per day.
The location matters twice here. It fixes the observing point the positions are computed for, and it fixes the time zone each sample is dated in. Check its coordinates and height in the Locations Editor before you generate.
Bodies
A topocentric graphic study offers the full 33-body Earth-frame catalog, including the Diurnal Angles group, so observer-relative angles such as the Ascendant can be plotted alongside the planets. Each body's curve is drawn in the color assigned to it in Graph Settings. See Bodies List.
Plotted Metrics
Only the four plottable metrics are offered. Sign Position has no graphic counterpart and is not in the list.
| Ecliptic reference plane | Equatorial reference plane | What it plots |
|---|---|---|
| Longitude | Right Asc | The body's position along the reference plane, in degrees. |
| Latitude | Declination | The body's position perpendicular to the reference plane, in degrees. |
| Distance | Distance | The body's distance, in AU. |
| Speed | Speed | The body's rate of motion, in degrees per day. |
Longitude is checked by default on a new graphic study. Each plotted metric gets its own value axis at the side of the plot.
After the Curves Are Plotted
The study locks when the generation completes, and the Run button becomes invisible until you unlock the study. The plot itself stays fully interactive:
- Show or hide a plotted metric. The plot redraws without generating the study again, because the generated series already carry all four metrics.
- Read a value off a curve.
- Adjust a value axis range.
- Pan and zoom the time window.
Changing which bodies are plotted does require unlocking and generating again.
A graphic study has no ephemeris table, so the Find and Export controls are hidden on it, and the count beneath the plot is labeled Point Count: rather than Record Count:. See Record Count.