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Overlay Tokens
Tokens are placeholders in curly braces, such as {EXPOSURE}, that are replaced with live values each time a text overlay is drawn. They let an overlay show camera settings, image statistics, weather, ML results and star detection without editing the overlay by hand. Add them to text overlays on the Overlay Settings tab.
- Any text inside
{...}in a text overlay is treated as a token. - Matching is case-insensitive:
{exposure},{EXPOSURE}and{Exposure}all give the same value. - If a token has no value for the current frame (unknown name, missing data, or a service that isn't set up), it is shown as
?. - Some tokens deliberately show
N/Awhen the value doesn't apply, for example sky tokens while the roof is closed. - Values are refreshed for every frame.
- The Preview on the Overlay Settings tab uses fixed sample values, not live data.
In ZWO Camera mode these come from the camera for every frame. In Directory Watch mode, see Directory Watch Mode below.
| Token | Description | Example |
|---|---|---|
{CAMERA} |
Camera model name | ZWO ASI676MC |
{EXPOSURE} |
Exposure time in seconds, two decimal places | 30.00s |
{GAIN} |
Gain | 100 |
{TEMP} |
Sensor temperature | 22.5 C |
{TEMPERATURE} |
Same as {TEMP}
|
22.5 C |
{TEMP_C} |
Sensor temperature in Celsius | 22.5°C |
{TEMP_F} |
Sensor temperature in Fahrenheit | 72.5°F |
{RES} |
Frame size as captured, before resizing or Output Framing | 3552x3552 |
{SESSION} |
Capture date | 2026-09-17 |
{DATETIME} |
Date and time the overlay was drawn (PC local time) | 2026-09-17 21:45:12 |
{FILENAME} |
Generated capture file name | capture_20260917_214512.png |
The temperature tokens show N/A if the camera doesn't report a temperature.
| Token | Description | Example |
|---|---|---|
{BAYER_PATTERN} |
Colour filter pattern used to debayer | BGGR |
{CAMERA_BIT_DEPTH} |
Sensor bit depth reported by the camera | — |
{IMAGE_BIT_DEPTH} |
Bit depth of the captured frame (8, or 16 in RAW16 mode) | 8 |
{PIXEL_SIZE} |
Pixel size in microns, as reported by the camera | — |
{ELEC_PER_ADU} |
Electrons per ADU, as reported by the camera | — |
Calculated from the captured frame (0–255 scale) before stretching and other processing. ZWO Camera mode only.
| Token | Description | Example |
|---|---|---|
{BRIGHTNESS} |
Mean pixel value | 42.7 |
{MEAN} |
Same as {BRIGHTNESS}
|
42.7 |
{MEDIAN} |
Median pixel value | 38.0 |
{MIN} |
Minimum pixel value | 0 |
{MAX} |
Maximum pixel value | 255 |
{STD_DEV} |
Standard deviation of pixel values | 18.25 |
{P25} |
25th percentile | 31.0 |
{P75} |
75th percentile | 47.0 |
{P95} |
95th percentile | 88.0 |
Available when an OpenWeatherMap API key and a location or coordinates are set in Settings (see Weather Setup). Data is cached for 10 minutes. If weather isn't configured, or the data can't be fetched once the cache has expired, these tokens show ?.
Weather tokens are not listed in the Tokens dropdown on the Overlay Settings tab, so type them into the text box.
| Token | Description | Example |
|---|---|---|
{WEATHER_TEMP} |
Current temperature | 8.0°C |
{WEATHER_FEELS_LIKE} |
Feels-like temperature | 5.2°C |
{WEATHER_CONDITION} |
Short condition | Clear |
{WEATHER_DESC} |
Detailed description | Clear Sky |
{WEATHER_HUMIDITY} |
Relative humidity | 72% |
{WEATHER_PRESSURE} |
Atmospheric pressure | 1013 hPa |
{WEATHER_WIND_SPEED} |
Wind speed | 3.2 m/s |
{WEATHER_WIND_DIR} |
Wind direction (16-point compass) | NNW |
{WEATHER_CLOUDS} |
Cloud cover | 12% |
{WEATHER_VISIBILITY} |
Visibility | 10.0 km |
{WEATHER_SUNRISE} |
Sunrise time (PC local time) | 06:42 |
{WEATHER_SUNSET} |
Sunset time (PC local time) | 18:35 |
{WEATHER_CITY} |
Location name returned by OpenWeatherMap | London |
{WEATHER_ICON_CODE} |
OpenWeatherMap icon code | 01n |
{WEATHER_ICON_URL} |
Web address of the current weather icon | https://openweathermap.org/img/wn/01n@2x.png |
{WEATHER_ICON_PATH} |
Local file path of the downloaded weather icon | — |
Available when Enable ML Analysis is on in the Image Processing tab; otherwise they show ?. See ML Models for accuracy and limitations.
| Token | Description | Example |
|---|---|---|
{ROOF_STATUS} |
Roof classifier result with confidence | Open (95%) |
{SKY_CONDITION} |
Clear, Partly Cloudy or Overcast, with confidence | Clear (87%) |
{STARS_VISIBLE} |
Whether the sky model sees stars | Yes |
{STAR_DENSITY} |
Star density: High (above 0.6), Medium (above 0.3) or Low, with the 0–1 score | High (0.85) |
The sky model only runs when the roof reads Open, so {SKY_CONDITION}, {STARS_VISIBLE} and {STAR_DENSITY} show N/A while the roof is closed. If the models could not be loaded, all four show ?.
Star detection runs on every frame, independently of the ML models.
| Token | Description | Example |
|---|---|---|
{STAR_COUNT} |
Number of detected stars | 847 |
{FWHM} |
Average star width (full width at half maximum), in pixels | 3.2 |
{SEEING} |
Seeing label from the FWHM: Excellent (up to 2.5), Good (up to 4), Fair (up to 6), Poor (up to 8), Bad (above 8) | Good |
These tokens show N/A when star detection is skipped:
- during daylight and twilight (the sun higher than 6° below the horizon), when latitude and longitude are set in Settings
- while the ML roof classifier reports Closed, if Skip Sky Features When Roof Closed is on
- from the next release, on frames judged not to show a night sky: sensor noise only, an exposure under the Minimum exposure floor, or a roof that reads Open with no stars detected on three frames in a row (see When the overlay is drawn)
In Directory Watch mode, camera information comes from the sidecar text file that capture software writes next to each image (the image file name plus .txt, for example frame_001.fits.txt). The file is expected to look like:
[ZWO ASI676MC]
Exposure = 30s
Gain = 100
Temperature = 22.5
Capture Area Size = 3840 * 2160
- The bracketed first line becomes
{CAMERA}. - Every
Key = Valueline becomes a token named after the key in upper case, for example{EXPOSURE}or{GAIN}. -
{RES}is built from a Capture Area Size line, and{TEMP}is copied from Temperature. -
{FILENAME}is the image file name,{SESSION}is the name of the folder containing the image, and{DATETIME}is the time the overlay was drawn. - Image statistics tokens are not calculated in this mode and show
?. - Weather, ML and star detection tokens work the same as in ZWO Camera mode.
Anything missing from the sidecar file shows ?.
| Token Group | ZWO Camera | Directory Watch | Additional Requirement |
|---|---|---|---|
| Camera | Yes | From sidecar file | — |
| Image Statistics | Yes | No | — |
| Weather | Yes | Yes | API key + location or coordinates |
| ML Models | Yes | Yes | Enable ML Analysis on |
| Star Detection | Yes | Yes | Night-time and roof open (see above) |
Camera info line:
{CAMERA} | {EXPOSURE} | Gain: {GAIN}
Result: ZWO ASI676MC | 30.00s | Gain: 100
Weather and conditions:
{WEATHER_CITY}: {WEATHER_CONDITION} {WEATHER_TEMP}
Wind: {WEATHER_WIND_SPEED} {WEATHER_WIND_DIR}
Result:
London: Clear 8.0°C
Wind: 3.2 m/s NNW
Observatory status line:
Roof: {ROOF_STATUS} | Sky: {SKY_CONDITION} | Stars: {STAR_COUNT}
Result: Roof: Open (95%) | Sky: Clear (87%) | Stars: 847
Timestamp only:
{DATETIME}
Result: 2026-09-17 21:45:12