Photometric Zero Points & Color Terms

Last updated: K. Olsen 27 August 2003

		Chip 1	Chip 2	Chip 3	Chip 4	Chip 5	Chip 6	Chip 7	Chip 8
Zero Point	U	2.217 (0.007)	2.220 (0.005)	2.231 (0.005)	2.254 (0.008)	2.234 (0.010)	2.215 (0.005)	2.216 (0.005)	2.227 (0.009)
	B	-0.107 (0.008)	-0.120 (0.008)	-0.115 (0.008)	-0.111 (0.009)	-0.111 (0.008)	-0.101 (0.008)	-0.106 (0.008)	-0.104 (0.008)
	V	-0.448 (0.008)	-0.472 (0.004)	-0.472 (0.004)	-0.476 (0.011)	-0.475 (0.004)	-0.471 (0.006)	-0.472 (0.005)	-0.475 (0.007)
	R	-0.636 (0.004)	-0.633 (0.004)	-0.648 (0.004)	-0.632 (0.004)	-0.628 (0.004)	-0.616 (0.004)	-0.629 (0.005)	-0.624 (0.006)
	I	0.089 (0.010)	0.118 (0.008)	0.076 (0.010)	0.094 (0.008)	0.094 (0.004)	0.123 (0.007)	0.113 (0.011)	0.088 (0.010)
Color Term	U	0.027 (0.019)	0.028 (0.015)	0.021 (0.015)	0.018 (0.019)	-0.025 (0.024)	0.019 (0.016)	0.015 (0.016)	-0.002 (0.021)
	B	-0.069 (0.010)	-0.062 (0.010)	-0.058 (0.010)	-0.055 (0.011)	-0.056 (0.010)	-0.079 (0.011)	-0.081 (0.010)	-0.068 (0.010)
	V	0.038 (0.009)	0.044 (0.005)	0.042 (0.005)	0.060 (0.012)	0.063 (0.005)	0.041 (0.007)	0.039 (0.006)	0.056 (0.008)
	R	-0.025 (0.008)	-0.037 (0.008)	-0.022 (0.008)	-0.032 (0.008)	-0.028 (0.008)	-0.045 (0.008)	-0.035 (0.010)	-0.029 (0.011)
	I	0.009 (0.009)	-0.002 (0.007)	0.008 (0.009)	0.006 (0.007)	0.003 (0.004)	-0.002 (0.006)	0.003 (0.011)	0.011 (0.010)

The equations used to fit the standard star photometry are of the form:

u = U + A₀ + A₁X + A₂(U-B)

b = B + B₀ + B₁X + B₂(B-V)

v = V + C₀ + C₁X + C₂(B-V)

r = R + D₀ + D₁X + D₂(V-R)

i = I + E₀ + E₁X + E₂(V-I)

where lowercase letters are the instrumental magnitudes (-2.5log(ADU sec^-¹)+25), X is the airmass, and capital letters are the standard magnitudes.

Updated on June 4, 2021, 9:37 am