Specifications

30 AUTOSTAR CCD PHOTOMETRY
Extinction Coefficients
(Not needed for differential photometry)
k'
vi
for (v – i) k'
v
for v
k'
vr
for (v – r) k'
bv
for (b – v)
k'
ri
for (r – i)
Zero Points
(Not needed for differential photometry)
ζ
vi
for (V – I) ζ
v
for V
ζ
ri
for (R – I) ζ
bv
for (B – V)
Note: While Extinction and Zero Points are not needed for
differential photometry, they are needed to determine the color
transformation coefficients.
The equations for CCD Differential Photometry then simplify to
the following:
(R – I) = γ * (r – i) V = v + ε * (B – V)
(V – I) = α * (v – i) (B – V) = μ * (b – v)
(V – R) = β * (v – r)
Once the color transformation coefficients have been determined,
they can be used along with the raw magnitudes to produce
corrected magnitudes.