Cosmic Origins Spectrograph Instrument Handbook for Cycle 17

10.5 Tabular Sky Backgrounds

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Below is a table of the high sky background numbers as plotted in Figure 10.1, for reference. The high sky values are defined as the Earthshine at 24° from the limb and by the typical zodiacal light of m_V = 22.7. Table 5.2xx lists the average value of the Zodiacal and Earthshine backgrounds (excluding the contributions from geocoronal emission lines) in each wavelength interval.

The line widths and intensities of some important geocoronal emission lines in the COS bandpass are listed in Table 10.4.

Table 10.2: Earthshine and zodiacal light in the COS PSA. The rates assume the high level in the ETC and are listed in units of FEFUs for the total COS PSA, which is 4.91 arcsec² in area.

Table 10.3:

Wavelength (Å)	Earthshine	Zodiacal Light	Total
1000	6.48 E-7	1.26 E -12	6.48 E -7
1100	1.66 E -6	6.72 E -11	1.66 E-6
1200	4.05 E-7	6.23 E-10	4.06 E -7
1300	2.66 E-8	3.38 E -9	2.99 E-8
1400	2.28 E -9	1.32 E-8	1.54 E-8
1500	1.95 E-9	2.26 E-7	2.28 E-7
1600	1.68 E-9	1.14 E-6	1.14 E-6
1700	6.09 E-8	3.19 E-5	3.19 E-5
1800	6.19 E-7	6.63 E-5	6.69 E-5
1900	2.30 E-6	1.05 E-4	1.07 E-4
2000	5.01 E-6	2.07 E-4	2.12 E-4
2100	6.97 E-6	5.95 E-4	6.02 E-4
2200	3.94 E-6	9.82 E-4	9.86 E-4
2300	1.83 E-6	9.67 E-4	9.69 E-4
2400	1.27 E-6	1.05 E-3	1.05 E-3
2500	1.37 E-6	1.01 E-3	1.01 E-3
2600	6.33 E-6	2.32 E-3	2.32 E-3
2700	2.66 E-5	4.05 E-3	4.08 E-3
2800	3.79 E-5	3.67 E-3	3.71 E-3
2900	2.17 E-4	7.46 E-3	7.68 E-3
3000	4.96 E-4	8.44 E-3	8.94 E-3
3100	1.04 E-3	9.42 E-3	1.05 E-2
3200	1.72 E-3	1.10 E-2	1.27 E-2
3300	2.18 E-3	1.34 E-2	1.56 E-2
3400	3.12 E-3	1.30 E-2	1.62 E-2
3500	4.06 E-3	1.31 E-2	1.72 E-2
3600	5.15 E-3	1.24 E-2	1.77 E-2
3700	5.89 E-3	1.49 E-2	2.18 E-2
3800	6.19 E-3	1.41 E-2	2.03 E-2
3900	7.80 E-3	1.39 E-2	2.17 E-2
4000	1.14 E-2	2.07 E-2	3.21 E-2
4250	1.13 E-2	2.17 E-2	3.40 E-2
4500	1.33 E-2	2.53 E-1	3.86 E-2
4750	1.35 E-2	2.57 E-2	3.92 E-2
5000	1.30 E-2	2.50 E-2	3.80 E-2

 

Table 10.4:

Table 10.5:

Airglow feature	Intensity
	Day			Night
	Rayleighs	FEFU-Å arcsec-2	FEFU-Å per PSA	Rayleighs	FEFU-Å arcsec-2	FEFU-Å per PSA
O i 911	17	0.006	0.011	8.3	0.003	0.006
O i 989	161	0.053	0.104	0.6	-	-
H i 1025	571	0.187	0.367	2.7	-	-
O i 1027	64	0.021	0.041	0	-	-
O i 1152	28	0.009	0.018	0	-	-
H i 1216	20,000	610	12,000	2,000	61	1,200
O i 1304	2,000	57	1,120	13	0.38	0.75
O i 1356	204	5	100	12.5	0.004	0.008
O i 2471	45	0.015	0.029	1	-	-

Strengths of important ultraviolet airglow lines