Abstract
We investigated various aspects of the in-orbit performance of SEVIRI on
Meteosat-10 (launch: 05 Jul 2012) and -11 (launch: 15 Jul 2015) with
images, where Mercury or Venus appeared in a corner. These objects are
of similar or smaller size than the instantaneous field of view, and
therefore they are well suited for checks of geometric requirements.
From comparing the position of Venus in different channels we conclude
that the North-South distance between the two focal planes is shorter
than the nominal value by 0.66 km at SSP (Sub-Satellite Point) with
Meteosat-10 and longer by 1.44 km at SSP with Meteosat-11. The tilt of
the detector array against the equator is less than 0.0037° for SEVIRI
on Metosat-10. The sampling with narrow channels is 3.0016 km, with a
one-sigma uncertainty of 30 cm at sub-satellite point. The tests we
carried out to check the geometric performance of the instrument
confirmed that SEVIRI is compliant with the requirements. The Point
Spread Function as determined from the image of a planet agrees well
with the expectations based on its combination with the finite impulse
response. Finally we determined the stability of the calibration
coefficients from the counts obtained on the planetary targets and found
the reproducibility of the measurements of planetary fluxes similar to
those of vicarious calibration targets. Hence planets are a promising
alternative to established methods of in-flight characterisation and
validation of imagers.