VENμS in orbit radiometric calibration
Abstract
For Venµs satellite, launched August 2 nd, 2017, the calibration and performance assessment activities of the commissioning phase took place in the second semester of 2017. In particular, the radiometric calibration includes fine tuning of the dynamic, identification of defective pixels, equalization of the detectors, absolute calibration, viewing parameters tuning. A special focus is made on specificities of the mission concerning level-1 radiometric calibration. As far as equalization is concerned: an unusual behavior has been observed on numerous pixels, called "radiometric spikes", on Venµs images. An improvement of the Venµs radiometric model has been implemented to remove these spikes. Absolute calibration using the moon consists in comparing the global irradiance of the Venµs moon image with the reference from ROLO radiometric model. Absolute calibration using simultaneous nadir observations with Sentinel-2 is also a specificity of the mission: since Sentinel-2A and Sentinel-2B are currently in orbit with very similar spectral bands, it is possible to use Simultaneous Nadir Observations of Venµs and Sentinel-2. The cross-calibration results will be presented and compared to other vicarious calibration methods. About stray-light modelling and correction: the optical stray-light level exceeds the requirements by far. Two types of stray-light are observed: local ghost and cross-talk ghost. Local stray-light model is computed as a global system MTF, whereas the estimated cross-talk contribution is subtracted from the image. The specific correction model and the in-flight results will be presented.
- Publication:
-
Sensors, Systems, and Next-Generation Satellites XXII
- Pub Date:
- September 2018
- DOI:
- 10.1117/12.2324118
- Bibcode:
- 2018SPIE10785E..13G