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A preliminary assessment of the in-flight radiometric calibration of theHinode EUV Imaging Spectrometer (EIS) is presented. This is done with the lineratio technique applied to a wide range of observations of the quiet Sun,active regions and flares from 2006 until 2012. The best diagnostic lines andthe relevant atomic data are discussed in detail. Radiances over the quiet Sunare also considered, with comparisons with previous measurements. Somedepartures in the shapes of the ground calibration responsivities are found atthe start of the mission. These shapes do not change significantly over time,with the exception of the shorter wavelengths of the EIS short-wavelength (SW)channel, which shows some degradation. The sensitivity of the SW channel atlonger wavelengths does not show significant degradation, while that of thelong-wavelength (LW) channel shows a significant degradation with time. By thebeginning of 2010 the responsivity of the LW channel was already a factor oftwo or more lower than the values measured on the ground. A first-ordercorrection is proposed. With this correction, the main ratios of lines in thetwo channels become constant to within a relative 20%, and the He II 256 Aradiances over the quiet Sun also become constant over time. This correctionremoves long-standing discrepancies for a number of lines and ions, inparticular those involving the strongest Fe X, Fe XIII, Fe XIV, Fe XVII, and FeXXIV lines, where discrepancies of factors of more than two were found. Theseresults have important implications for various EIS science analyses, inparticular for measurements of temperatures, emission measures and elementalabundances.

A revised radiometric calibration for the Hinode/EIS instrument