Table 1.

Summary of the photometers

Photometer	Photodiode	Shunt resistance (GΩ)	Filter source	Calibration (nA/lx)	F (2856 K)	f1′ (%)
1	S1227-1010BQ	5	NRC	10.116	1.002	6.00
2	S1227-1010BQ	5.2	NRC	10.067	1.003	5.97
3	S1226-8BQ	7	NPL	2.821	0.954	7.26
4	S1227-66BQ	6.6	PRC	2.350	0.990	2.55
5	S1226-8BQ	7	PRC	2.335	0.989	2.35
6	S1226-8BQ	7	PRC	2.331	0.990	2.37
7	S1226-8BQ	7	PRC	2.341	0.987	2.79
8	S1226-8BQ	4.3	PRC	2.334	1.000	1.43