Spectral Features
Spectral features are named emission or absorption lines that are overlaid on the focal-plane plot as vertical marker lines. They help you verify that a key wavelength falls within a slit passband at the chosen grating angle.
Table of contents
Opening the Editor
Click the Features chip below the mode summary. The editor opens as a draggable floating window.
Feature Table Columns
| Column | Description |
|---|---|
| Plot | Checkbox — uncheck to hide the line without deleting it |
| Name | Label displayed as an annotation on the plot |
| Wavelength | Line centre wavelength in Å (0.001 Å step) |
| Color | Line colour — click the swatch to open the colour picker, or type a hex value |
| Slit key | Name of the slit this feature belongs to. Leave blank to show on all slits |
Line Width
The line width control in the editor header sets the stroke width for all feature lines (0.01 – 10, default 0.75). Adjust this to keep annotations readable at different PDF export DPI settings.
Editing
- Click a cell to edit in place.
- Click Add feature to append a new row.
- Click ✕ on a row to remove a feature.
- Toggle the Plot checkbox to temporarily suppress a line on the plot without losing its definition.
Tips
Name features with the ion and wavelength, e.g. OI 6300 — this label appears directly on the plot annotation.
Use the Slit key column to assign a feature to one slit only. This is useful when the same wavelength falls in different orders for different slits.