Observatory Sky Monitor is a comprehensive solution for a permanently installed monitoring instrument at an observatory. It measures and reports the Sky brightness levels, Sky temperature and other derived parameters, as well as outdoor ambient conditions including the temperature, humidity, dew point and rain conditions.

The instrument installs simply and quickly on any flat surface using 2 (user supplied) screws. It does not require long data or USB cables. The reports are made via the integrated Wi-Fi, to any 2.4GHz access point within approximately 100m range (terrain dependent). It only requires a DC power supply (user supplied) to its 2 pin, IP68 rated connector. Thus a short wire run to the observatory is all that is required.

The instrument contains two dew/ice heaters to prevent formation on the Sky Brightness lens and the rain sensor.

Observatory Sky Monitor interfaces to ASCOM or its own native application via the Wi-Fi connection. It does not require complex IP or port settings, only a simple Access Point setup.


  • Filtered Sky Brightness Measurement in MPAS2, NELM and Bortle
  • Sky Temperature and Sky Delta to detects even smallest cloud whiffs
  • Atmospheric Perceptible Water column in mm
  • Ambient parameters such as Temperature, %RH and Dew Point
  • Dew Point Alarm
  • Wi-Fi Connectivity
  • No data cables – only an inexpensive 2 wire power line
  • ASCOM drivers for supported readings
  • Native monitoring application for an all-encompassing data monitoring
  • Integral dew/ice heaters
  • IP68 rated device
  • Simple installation

SQM Filtering Response is similar to that of other widely used instruments. Typical variance is roughly 0.010 MPAS2.  

SQM (Sky Brightness)    
Range 7.5 to 23+ Mag per Arc sec2 (MPAS2)
Resolution 0.001 Mag per Arc sec2 (MPAS2)
Noise (typ) 0.003 Mag per Arc sec2 below 20 MPAS2
Beamwidth (HWHM) 13 degrees
Update Rate 5 sec typ.  @ 19 MPAS2 Slowest: 30 sec at 23 mpas
Filter BG-39 Similar to CM500
Dew/Ice Heater Included  
STM (Sky Temperature)    
Range -70 to 60 degrees C
Resolution 0.01 degrees C
Noise 0.01 degrees C RMS
Beamwidth (HWHM) 12 degrees
Accuracy TBD degrees C
Update Rate 1 sec
Emissivity 0.7 set to typical Sky
PWV (Precipitable Water Vapor) 0 to 20 mm (reduced accy. Above 20mm)
Measured Ambient    
Temperature -20 to 70 C
RH 0 – 99.9 %
DP -20 to 70 C
Protocol 802.11 b/g/n 2.4 GHz
RF Power 100 mW
Power Supply    
Voltage 10 to 24 VDC
Supply Current 1 ADC
Connector SP-13, 2 PIN IP68 rated, Plug & Socket Provided
Rain Sensor    
Dew/Ice Heater Included  
Environmental and Water Ingress  
Protection Level IP-68 / NEMA 6P