Question

Calculate the magnitude of the faintest object that can be detected by an optical
telescope of diameter 5.0 m.

Answer 1

Limiting magnitude is equal to

$$5 \log_{ 10} { \frac {D_1} { D_0}} (1)$$

where D₀=0.006 m (the diameter of the eye's dark adapted)

In our case, D₁=5 m

Using (1) we got:

magnitude is equal to 14.6

Answer:

14.6