The CHIANTI Atomic Database and Instrument Calibration: a Symbiosis

The CHIANTI atomic database comprises a comprehensive, accurate and up-to-date database of atomic parameters, necessary for emission-line spectroscopy. The suite of user-friendly software allows plasma diagnostics to be carried out. Since its release in 1996, CHIANTI has become a standard resource for the analysis of solar spectra. Accurate atomic data can provide the foundation for in-flight instrument calibrations. Conversely, an accurate instrument calibration can provide a check on atomic parameters. The internal consistency of spectral-line intensities can be used to highlight specific anomalies. In this paper, we illustrate how CHIANTI has been used to validate the calibration of solar EUV instruments: SOHO-CDS, -SUMER, -EIT and SERTS. In addition, we show how anomalous spectral-line intensities indicate the need for more accurate atomic calculations.