Hardware & Telemetry Shipped

SQMeter

Mobile sky quality measurement tool for astronomers

Overview

A portable sky quality meter that measures zenith brightness (MPSAS), NELM, and Bortle class from the field, publishing readings over MQTT and a REST API for logging and display.

The problem

Accurate sky quality measurement requires dedicated equipment with no convenient way to log readings, correlate them over time, or share them with other observers in the field.

What I built

An ESP32-based sensor unit paired with a REST/MQTT telemetry API. Readings include MPSAS, NELM estimation, Bortle classification, and ambient sensor data, all timestamped and stored for analysis.

Technical details

Firmware is written in C++ for ESP32. The backend is a lightweight REST API exposing a time-series of readings. MQTT publish allows real-time consumption by dashboards or other devices. Data schema is versioned and validated.

Live demo

sqm.dean0.co.uk — bash

$ curl https://sqm.dean0.co.uk/api/v1/readings/latest

Live readings

MPSAS

21.38

NELM

6.20

Bortle

3 (Rural)

Lux

0.0023

Stack