Inspector
Role
The Inspector module analyses the optical quality of the star field across the whole image. It produces three complementary representations: an HFR map by zone, a star elongation map, and a corner comparison mosaic. It is used to diagnose optical defects such as tilt, coma, or field curvature.
Analysis can be performed on an image acquired live from the camera, or on a FITS file loaded from disk.
Required devices
| Device | Role |
|---|---|
| Camera | Image acquisition (optional if loading from file) |
Parameters
Acquisition
| Parameter | Description |
|---|---|
| Exposure | Exposure duration in seconds |
| Gain | Camera gain |
| Offset | Camera offset |
| Focal length | Optical focal length in mm — used to convert HFR values to arcseconds |
| Corner size (pixels) | Width in pixels of the patches extracted for the corner mosaic |
Analysis
| Parameter | Description |
|---|---|
| Zoning | N×N grid for per-zone analysis (from 1×1 to 64×64) |
Output maps
HFR map
The HFR map divides the image into an N×N grid (according to the Zoning parameter). For each zone, the average HFR is computed from all detected stars, then smoothed using an 8-neighbour average.
Each zone is colour-coded from green (best HFR) to red (worst HFR).
Overlaid on the map:
- Blue circles around each detected star, with radius proportional to the individual HFR
- A white quadrilateral connecting the centres of the four quadrants, whose shape reflects the HFR distribution — a perfect square indicates ideal uniformity
- HFR value for each quadrant (top-left, top-right, bottom-left, bottom-right) and overall HFR, expressed in arcseconds
Shape map (aberrations)
The shape map analyses star elongation per zone. For each zone in the grid, a line segment is drawn:
- Orientation: direction of the stars’ principal axis (mean angle)
- Length: proportional to the elongation
a/b − 1(major axis / minor axis ratio)
Short, uniform segments across the image indicate round stars. Long segments at the edges signal coma or astigmatism.
Corner mosaic
The mosaic assembles nine patches of size Corner size extracted from nine positions of the original image, arranged in a 3×3 grid:
Top-left | Top-centre | Top-right
Mid-left | Centre | Mid-right
Bot-left | Bot-centre | Bot-rightThis view allows direct comparison of star quality at the centre and edges of the field.
Loading from file
The Select a file field lets you load a FITS file from disk and analyse it without triggering an acquisition. Analysis starts automatically when the path is entered.
Actions
| Action | Description |
|---|---|
| Shoot | Acquires a single image and runs the analysis |
| Loop | Continuous acquisition and analysis — repeats automatically until aborted |
| Reload | Reloads and re-analyses the last image or file |
| Abort | Stops the current loop |