KTM-001 — What the First Station Actually Measures

Temperature and humidity

The DHT22 shows the expected diurnal structure clearly. Its documented weakness — reading about 2°C high at high humidity — is logged in the station's calibration record. We publish raw values with the calibration log alongside, so anyone using the data can apply the correction knowingly.

Pressure

At 1,350 m the barometric formula puts ambient pressure around 865 hPa, and that is the scale the BMP280 operates at here. Pressure is more than weather: it is the atmospheric-depth reference the muon programme will need, since muon flux at ground level depends on how much atmosphere sits above the detector.

The proxy problem

The MQ-135 is not a particulate sensor. It responds to a mixture of gases and drifts with temperature and humidity, so we publish its raw signal labelled as an uncalibrated proxy — useful for relative patterns, not for concentrations. A reference-grade particulate module (PMS5003) is designed and waiting on component funding; when it is fitted, co-locating against Kathmandu's existing reference stations is the calibration plan.

Quality flags and the demo notice

The ingest pipeline flags any reading outside physical bounds as suspect rather than silently dropping it. And until the station's cloud sync ships, the public dashboard carries a demonstration-data notice on every chart — if you see that banner, the values shown are simulated.