This module analyzes Allsky images for cloud cover and writes the (zenith) cloud fraction and cloud change into an Influx DB. It also includes a web service to query celestial positions for the limiting magnitude, which is calculated in an intermediate step.
Best paired with: pyobs-allsky
The module listens for a new image from the configured camera. If a new image has been captured, an image analysis pipeline is run on the image, depending on the solar altitude when the image was captured. Currently there is only a "night" pipeline, which works best after astronomical twilight (solar altitude below -18°). This pipeline estimates the limiting magnitude of each pixel based on the visibility of the stars. Pixels are considered cloudy if their limiting magnitude falls below a defined threshold.
Returns the cloudiness value of the analyzed sky position closest to the requested position.
Routes:
/query/point?ra={Right ascension in degree}&dec={Declination in degree} or
/query/point?alt={Altitude in degree}&az={Azimuth in degree}
Example:
/query/point?alt=90.0&az=0.0
Result:
| Field | Type | Description |
|---|---|---|
| obs_time | float | Observation Unix time of the last analyzed image |
| value | bool | If it is cloudy at the requested point |
Returns the cloud fraction within the requested great circle.
Routes:
/query/area?ra={Right ascension in degree}&dec={Declination in degree}&radius={Radius in degree} or
/query/area?alt={Altitude in degree}&az={Azimuth in degree}&radius={Radius in degree}
Example:
/query/area?alt=90.0&az=0.0&radius=10.0
Result:
| Field | Type | Description |
|---|---|---|
| obs_time | float | Observation Unix time of the last analyzed image |
| value | float | Cloud fraction in the requested area in percent |
See example.yaml