Small instruments for light pollution research

We have developed several devices to monitor sky brightness at night

Lucía García, Jaime Zamorano, Cristobal García, Carlos Tapia, Rafael González et al

TESS-W photometer

TESS-W is the first version of a series of inexpensive but reliable photometers that are used to measure night sky brightness. This photometer has been designed based on Cristobal García photometer TESS.

  • Itis mounted on a weatherproof enclosure (83x60x32 mm) and sends automatically the brightness values to a data repository using a WIFI to connect the Internet so can be used as a fixed station toconstantly monitor the sky brightness at night.
  • The device includes an infrared sensor to estimate the cloud coverage.
  • It has been calibrated at LICA laboratory the quality of the data is scientifically accurate.
  • The band pass is extended to the red with respect of that of the Sky Quality Meter (SQM).
  • The photometer could also be used in local mode connected to a computer or tablet to gather data from a moving vehicle.
  • The photometer was developed within STARS4ALL project, a collective awareness platform for promoting dark skies in Europe, funded by the EU.


Hundreds of units have already been deployed around the world. The photometers on the TESS network share their measurements in an open data repository.

Browse the poster presented during the IAU 2018 in Vienna for more info (left) or check the following article describing the device:

TESS-P photometer

TESS-P has been designed to use as a hand help portable photometer

  • The small display shows the measurements. The photometer can be connected via bluetooth to the smartphone app to display and to record your observations.
  • There are accelerometers included to provide the pointing of the photometer
  • The inside battery is enough to register sporadic measures. If you want to use it on the go or for a night long series of observations you should connect to a power bank.
  • Download and install TESS-P app for Android and record your measurements along with your GPS location.


TAS allows you to obtain all-sky brightness maps

  • The mount should be leveled and oriented to north.
  • After connecting to the TESS-P smartphone app you only need to press the small button to initiate the full automatic scanning.
  • The 140 data point all along the celestial vault are recorded and they are used to create a map.
  • The all-sky night sky brighness map is similar to those of the NixNox Project.
  • Optional watertight case for outdoor and transport protection


This is a portable, cheap, open source NSB photometer controlled by a raspberryPi that gathers information in RGB colors and SQM bands.The working prototype has 4 channels and 4 detectors, custom made electronics based on TESS. Cheap filters and cloud sensor.

COELOFOT has been presented in the XXIX IAU General Assembly, Hawaii. August 3-14 (2015)


Professor Jaime Zamorano:

Facultad de Ciencias Físicas UCM

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