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Lecture 7 Photometry - Coggle Diagram
Lecture 7 Photometry
Two implications in photometry
atmoshpheric extinction
almost proportionate to airmass
color
determine second order extinction terms
Taylor expansion
calculate SNR(unfinished)
Poisson statistics： σ=λ
photons
electrons
error known
estimated background
readnoise
calculate: the delivery of error
The first kind: Aperture Photometry
basic principle
counting photons from the souce
substract an estimated background count
use median or mode
count photons in a ring of a fit size
its extension
more requirement of precision:difference image photometry
an extended source: extended source photometry
The second kind: Differential Photometry
basic principle
converting to magnitude
use known objects to compare with the unknown one
calculation method
calculate the average of known ones instead of median or mode