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Photometry - Coggle Diagram
Photometry
Basic Steps & Methods
CCD & CMOS
CCD with lower noise but higher price
$$C = {Efficiency \times PhotonRate + Dark \over Gain} + Bias$$
Apeture Photometry
Subtract an estimated background mode count
PSF Photometry
Fitting a PSF
Difference Image Photometry
Calculate SNR
Photon count follows Poisson statistics
Long exposure boosting SNR by half power
Signal
$$S_{net} = Signal + Bg - \hat{Bg} - Dark +\epsilon$$
Noise
$$\sigma_N^2=S_{total}+\sigma_B^2+N_d+n_sN_r^2$$
$$\sigma_B^2 = B_{total} \cdot {n_S^2 \over n_B^2}$$
Differential Photometry
$$M_{true}(target)-M_{true}(std) = M_{inst}(target) - M_{inst}(std)$$
$$M_{true}(target) = M_{inst}(target) + {1\over N}\sum_{i}^N (M_{true}(std_i) - M_{inst}(std_i))$$
Calibrate to Magnitudes
Atmospheric Extinction
$$m_{inst}=m-k(\lambda)Airmass$$
Extinction: U>B>V>R>I
$$C_0 = C - k(C)X$$