I'm compiling a carbon star list in SS. Can you explain why the visual magnitude for the stars is different to the magnitude range listed in the variability data section. For example TT Tauri has a visual magnitude of 8.02, but a listed magnitude range of 10.2 to 12.2. Carbon stars are variable and hence that's why they have a magnitude range, but why is the visual magnitude and the magnitude range so different. Is the magnitude range measured in the photographic/blue part of the spectrum, and that's why it is fainter than the visual magnitude.
Star Magnitude Discrepancy