How to populate vtkColorSeries with specific RGB values?

How to populate a vtkColorSeries with specific RGB values? I see method vtkColorSeries::SetColor(index, vtkColor3ub &) and examples that populate the series with vtkNamedColors, e.g. to set the 0th color in the series:

colorSeries->SetColor(0, colors->GetColor3ub("turquoise_blue"))

But how would I set the 0th color to R=0.00, G=1.00, B=0.94? How can I create a vtkColor3ub from just RGB values rather than named colors? Google search of “vtkColor3ub rgb” yields mostly references to vtkNamedColors…

Thanks
Tom