photometry
Photometry
Aperture Photometry
Difference Image Photometry
CCD/CMOS
CCD: charge-coupled device
CMOS: Complementary metal–oxide–semiconductor
estimate background
substract
count photon
mode count
PSF
PSF matching
intensity matching
precise (subpixel) alignment
extended source photometry
SNR
noise
SNR=Snet-√S
Signal-to-Noise Ratio
dark current
read noise and digitization error
Sky
σB^2=B*ns^2/nb^2
Nd=dark current
S=Stotal+σB^2+Nd+ns*Nr
Nr=read noise
Snet = (S+B) – Bestimated – dark + ϵ
Magnitude
M=C-2.5lgN+2.5lgt
F=N/t
Differential photometry
instrumental zero point magnitude
Mt(target)-Mt(standard) = Mi(target) - Mi(standard)
complications
Atmospheric extinction
Instrumental to Standard Magnitudes
x=secz
mins=m--kx