In the Near Infrared (NIR) regions of the solar spectrum (from 800 nm to 2.5 micron), the measurement of the respective irradiance from space can be a laborious task due to the low energy of the NIR photons and the inherent difficulty to track the instruments calibration and complex behaviour in a space environment.
For several atmospheric windows it is possible to measure the NIR irradiance from the ground and extrapolate it to the top of the atmosphere with great accuracy, and with the added benefit of a close tracking of the instrument’s calibration.
Our group carried out these high accuracy measurements at two high altitude world renowned observatories where the conditions of atmospheric stability are excellent:
- Izaña Observatory (IZO) on Tenerife
- Mauna Loa Observatory (MLO) on Hawaii
The results obtained in the NIR spectrum for both campaigns have contributed greatly to the definition of the absolute level of the Sun’s NIR spectrum.
The BIRA-IASB radiometric laboratory experienced a significant growth in equipment and expertise in the early 2000’s during the development and characterization phase of the SOLAR/SOLSPEC instrument.
This expertise was successfully applied to the characterization of:
- ground-based broadband NIR and UV instruments
- space instruments such as: SPICAM LIGHT on board Mars Express, SODISM on board PICARD and NOMAD/UVIS on board ExoMars
The laboratory is nowadays dedicated to the characterization of the MAJIS instrument to be flown on board JUICE. New calibration units are regularly developed to allow specific radiometric characterization to new instruments such as ALTIUS.