# Luminosity and flux

1. Sep 28, 2003

### StephenPrivitera

L=A[sig]T4
f=L/A=[sig]T4
Where does time come into these equations?

If one telescope of a known diameter can reach a certain magnitude, it is easy to find what magnitude a different telescope of known magnitude can reach. But if a telescope integrating over 10s can reach a certain magnitude, how can we determine what magnitude the same telescope will reach integrating over 1hr?

Also, what does it mean for something to have a spectral resolution of 5?

Last edited: Sep 28, 2003
2. Sep 28, 2003

### Nereid

Staff Emeritus
What are the units of [sig]?
Assuming you're still way above sky noise, presumably.
If one star has a magnitude of 5, and another 10, what is the ratio of the energy received, in unit time, by the same telescope?
How many seconds are there in an hour?

Last edited: Oct 2, 2003