24 October 2020 11:52 AM Page 6 What is 2.5 log10(t) +CV for the G image you used for your Colour -Magnitude diagram? What is 2.5 log10(t)+CB for the B image you used for your Colour- Magnitude diagram?When you make your plot with Top Cat you should add these constants to your plotted values, e.g. where you’d have Magnitude_1, you’d put Magnitude_1 + X where X is the appropriate value. With the constant added, does your visual magnitude range seem more reasonable? What is the effect of the zero-point magnitude on the colours? Does the difference between the instrumental and apparent magnitudes change or distort the CMD? What is the effect o