Table 2.

The average NSB in different colors and the color indices for the three nights at Alt 90°

Az degrees	Alt degrees	Uavg mag/arcsec2	Bavg mag/arcsec2	Vavg mag/arcsec2	Ravg mag/arcsec2	Iavg mag/arcsec2	U–B	B–V	V–R	R–I
0	90	20.44	20.26	19.27	18.57	17.84	0.18	0.99	0.70	0.73
10	90	20.29	20.44	19.38	18.68	17.93	− 0.15	1.06	0.70	0.75
20	90	20.24	20.47	19.37	18.67	18.02	− 0.23	1.10	0.70	0.65
30	90	20.46	20.47	19.48	18.70	17.68	− 0.01	0.99	0.78	1.01
40	90	20.44	20.51	19.47	18.78	17.98	− 0.06	1.04	0.69	0.79
50	90	20.53	20.03	19.47	18.77	18.11	0.49	0.57	0.70	0.66
60	90	20.55	20.08	19.41	18.70	17.99	0.46	0.68	0.71	0.71
70	90	20.26	20.28	18.36	17.55	17.89	− 0.02	1.92	0.81	− 0.34
80	90	20.45	20.40	19.38	18.27	17.30	0.05	1.02	1.12	0.97
90	90	20.52	20.50	19.04	18.29	17.45	0.01	1.46	0.75	0.84
100	90	20.58	20.54	19.53	18.82	18.15	0.04	1.01	0.71	0.67
110	90	20.59	20.54	19.53	18.84	18.17	0.05	1.01	0.70	0.67
120	90	20.60	20.54	19.54	18.82	18.18	0.06	1.00	0.72	0.64
130	90	20.59	20.54	19.53	18.80	18.18	0.06	1.00	0.73	0.62
140	90	20.61	20.54	19.53	18.80	18.16	0.07	1.01	0.73	0.63
150	90	20.59	20.54	19.53	18.80	18.15	0.05	1.01	0.74	0.64
160	90	20.61	20.53	19.54	18.80	18.16	0.07	1.00	0.74	0.64
170	90	20.59	20.54	19.55	18.80	18.17	0.04	1.00	0.75	0.63
180	90	20.49	20.43	19.43	18.68	17.97	0.06	1.00	0.75	0.71
190	90	20.56	20.47	19.45	18.70	17.97	0.09	1.02	0.75	0.72
200	90	20.58	20.48	19.47	18.71	18.03	0.09	1.01	0.76	0.68
210	90	20.57	20.52	19.52	18.75	18.09	0.05	1.00	0.77	0.65
220	90	20.53	20.54	19.48	18.74	18.06	− 0.01	1.06	0.74	0.67
230	90	20.59	19.24	19.54	18.79	18.14	1.35	− 0.30	0.75	0.64
240	90	20.59	19.03	19.54	18.78	18.17	1.56	− 0.51	0.76	0.62
250	90	20.00	20.42	19.25	17.46	17.87	− 0.41	1.16	1.79	− 0.41
260	90	20.05	20.37	19.18	17.40	16.41	− 0.32	1.19	1.78	0.99
270	90	20.44	20.39	18.92	17.58	16.54	0.05	1.47	1.34	1.05
280	90	20.51	20.52	19.49	18.79	18.13	− 0.02	1.03	0.70	0.65
290	90	20.49	20.52	19.49	18.79	18.13	− 0.03	1.03	0.70	0.66
300	90	20.50	20.52	19.49	18.79	18.14	− 0.01	1.03	0.70	0.65
310	90	20.53	20.51	19.49	18.80	18.14	0.02	1.02	0.70	0.66
320	90	20.54	20.51	19.50	18.80	18.15	0.03	1.01	0.70	0.65
330	90	20.57	20.51	19.52	18.82	18.15	0.07	0.99	0.70	0.66
340	90	20.53	20.51	19.51	18.80	18.14	0.02	1.01	0.70	0.66
350	90	20.59	20.52	19.52	18.82	18.16	0.07	1.00	0.70	0.66
360	90	20.52	20.29	19.30	18.60	17.88	0.22	1.00	0.70	0.71