Fit TGraphPolar


I am fitting a user defined function to a TH1 histo, which works okay. As I would also like to have the same data fitted with the same function in a polar diagram, I define an array that is filled using TH1::GetBinContent(). This I plot as a a TGraphPolar, because I understand that it is not possible to plot a TH1 in a polar diagram, correct? This TGraphPolar is afterwards fitted with the same function in the same range as before. The fit parameter I am interested in, differs for the two fits on the order of about 5-10%. As the data is identical, I wonder whether the fit routine works differently in a TGraphPolar than in a TH1? If so, should I better rely on the value from fitting the TH1 in cartesian coordinates?

Thanks for your help!