Metric Charts
Night Summary can generate charts showing how imaging metrics changed over the course of your session. This helps you spot trends, correlations, and problems.
Available at Full detail level only.
Primary and Secondary Metrics
Each chart’s Y-axis can show up to two metrics:
- Primary Metric — plotted as the main data series (left Y-axis, solid line)
- Secondary Metric — optional second series on a separate right Y-axis (dashed line). Set to “None” to show only the primary.
Plotting two metrics on the same Y-axis is useful for spotting correlations — for example, HFR vs. temperature to see how focus changes with cooling.
X-Axis Options
The horizontal axis can be set to any of the following:
| X-Axis | Description |
|---|---|
| Time | Wall-clock timestamp of each exposure (default) |
| Frame Index | Sequential frame number (1, 2, 3…) |
| Any metric | Use any metric listed below as the X-axis for correlation plots |
Setting the X-axis to a metric instead of time is useful for correlation analysis — for example, “does my HFR correlate with altitude?”
Available Metrics
All of these can be used as primary metric, secondary metric, or X-axis:
| Metric | Unit | Notes |
|---|---|---|
| HFR | pixels | Half-flux radius — NINA’s native focus quality metric |
| FWHM | arcsec | Full-width at half-maximum. Requires the Hocus Focus plugin. |
| Guiding RMS | arcsec | Total guiding RMS from PHD2 or similar |
| Focuser Temp | C | Temperature sensor on the focuser. Requires a focuser with built-in temp sensor. |
| Ambient Temp | C | Outside air temperature. Requires a weather data source. |
| Eccentricity | Star elongation metric. Requires the Hocus Focus plugin. | |
| Altitude | degrees | Target altitude above the horizon |
| Airmass | Atmospheric airmass (derived from altitude) | |
| Humidity | % | Relative humidity. Requires a weather data source. |
| Focuser Position | steps | Motorized focuser position in steps |
| Sky Quality | mag/arcsec2 | Sky brightness. Requires a sky quality meter. |
| Cloud Cover | % | Cloud coverage. Requires a cloud sensor. |
| Camera Temp | C | Sensor cooling temperature |
| Dew Point | C | Dew point temperature. Requires a weather data source. |
| Wind Speed | m/s | Wind speed. Requires a weather data source. |
| Pressure | hPa | Atmospheric pressure. Requires a weather data source. |
| Star Count | Number of stars detected in each frame | |
| Azimuth | degrees | Target azimuth |
| Seeing FWHM | arcsec | Atmospheric seeing measurement. Requires an ASCOM-compatible seeing monitor connected as a NINA weather data source. |
| Median ADU | ADU | Image median pixel value. Useful for tracking sky background brightness changes throughout a session (e.g. moonrise, twilight). |
Metrics that require external hardware or plugins will show no data if the equipment isn’t connected. The chart simply omits data points where the metric value is zero or missing.
Event Markers
When the X-axis is set to Time, you can overlay vertical dashed lines on the chart marking specific events that occurred during the session:
| Marker | Label | Color | Triggered by |
|---|---|---|---|
| AutoFocus | AF | Purple | Each AutoFocus run |
| Meridian Flip | MF | Amber | Meridian flip events |
| Safe | S | Green | Safety monitor transitions to Safe |
| Unsafe | US | Red | Safety monitor transitions to Unsafe |
Each marker type can be toggled independently in Options → Metric Chart Settings (see the Settings Reference for exact toggle names). The colors match the markers shown on the session event timeline at the top of the report.
Hover over any marker to see a tooltip with the event description and timestamp. Markers are only displayed when the chart’s X-axis is set to Time — they don’t appear for Frame Index or metric x-axes.
Additional Charts
You can add up to 4 additional charts beyond the primary one:
- Click + Add Chart in the settings
- Configure the primary metric, secondary metric, and X-axis for the new chart
- Click the X button next to a chart to remove it
Each additional chart has its own independent metric selections. This lets you create a dashboard-style report with multiple views of your session data — for example, one chart for HFR over time, another for temperature vs. focuser position, and a third for guiding RMS vs. altitude.
Chart Interaction
In the HTML report, chart data points show hover tooltips with the exact timestamp, metric value, and the filter used for that exposure (e.g. 22:15 — 1.67 px [Ha]). This makes it easy to identify specific frames with unusual values or spot filter-specific patterns.
Common Chart Configurations
Here are some useful metric combinations to try:
| Purpose | Primary | Secondary | X-Axis |
|---|---|---|---|
| Focus quality over time | HFR | Focuser Temp | Time |
| Guiding performance | Guiding RMS | Altitude | Time |
| Focus vs temperature | HFR | — | Focuser Temp |
| Star count consistency | Star Count | Humidity | Time |
| Altitude effects | HFR | Airmass | Altitude |
| Seeing conditions | FWHM | Wind Speed | Time |
| Sky background | Median ADU | — | Time |