Koen, Chris2013-10-202013-10-202009Koen, C. (2009). Correcting CCD photometry of stars for seeing effects. Monthly Notices of the Royal Astronomical Society, 395: 531–5360035-8711http://hdl.handle.net/10566/776Systematic variability in stellarmagnitudes, as derived from profile fitting to CCD images,may in some instances be due to variable seeing. It is suggested that this happens in cases where the stars are unresolved pairs, typically with sub-arcsecond separation between the components. It is shown that the fitting of suitable Generalised Additive Models to time series photometry can disentangle intrinsic stellar variability and seeing-induced brightness changes. It is possible that there will be a fixed seeing response associated with a given star which exhibits the effect: estimation of this response from several long photometric runs is demonstrated.en© 2010 copyright Oxford University Press. This file may be freely used for educational purposes, as long as it is not altered in any way. Acknowledgement of the authors and the source is required.Methods: data analysisTechniques: photometricArticle