Luminosity, Flux, Time: What Do They Mean?

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SUMMARY

The discussion centers on the relationship between luminosity, flux, and time in astronomical observations, specifically using the equations L=A[sig]T4 and f=L/A=[sig]T4. Participants explore how to calculate the magnitude a telescope can reach over different integration times, such as comparing 10 seconds to 1 hour. The conversation also addresses the concept of spectral resolution, questioning its implications and the role of time in these calculations. Key questions include the units of [sig] and the energy ratio received from stars of different magnitudes.

PREREQUISITES
  • Understanding of astronomical concepts such as luminosity and flux
  • Familiarity with telescope operations and integration times
  • Knowledge of spectral resolution and its significance in astronomy
  • Basic mathematical skills for calculating energy ratios and magnitudes
NEXT STEPS
  • Research the impact of integration time on telescope magnitude sensitivity
  • Learn about the calculation of energy ratios between stars of different magnitudes
  • Explore the concept of spectral resolution and its measurement techniques
  • Study the relationship between luminosity, flux, and distance in astronomical contexts
USEFUL FOR

Astronomers, astrophysics students, and anyone interested in understanding the principles of telescope performance and light measurement in astronomy.

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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?
 
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Where does time come into these equations?
What are the units of [sig]?
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?
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?
 
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