12.14 COS Spectral Elements and Central
Wavelengths

The following table specifies the legal COS spectral element/wavelength combinations for the COS/FUV and COS/NUV configurations.

Note: the wavelengths in this table are listed in OP-01, Rev 17 (Feb.6, 2002).

Table 12.3: COS Spectral Elements and Central Wavelengths

Configuration	Spectral Element	Central Wavelengths (Angstroms)
COS/FUV	G130M	10551, 10961 and 12221 1291, 1300, 1309, 1318, 1327
	G140L	1105, 1280
	G160M	1577, 1589, 1600, 1611, 1623
COS/NUV	G185M	1786, 1817, 1835, 1850, 1864, 1882, 1890, 1900, 1913,1921, 1941, 1953, 1971, 1986, 2010
	G225M	2186, 2217, 2233, 2250, 2268, 2283, 2306, 2325, 2339, 2357, 2373, 2390, 2410
	G230L	2635, 2950, 3000, 3360
	G285M	2617, 2637, 2657, 2676, 2695, 2709, 2719, 2739, 2850, 2952, 2979, 2996, 3018, 3035, 3057, 3074, 3094
	MIRRORA2	N/A
	MIRRORB3	N/A

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1

ACQ modes not allowed with this central wavelength.

2

The MIRRORA spectral element positions a flat mirror in the beam to produce an image of the sky with a field of view slightly larger than the diameter of the aperture. If you intend to produce an image and there are no special bright object concerns, MIRRORA should be used.

3

MIRRORB uses the same mirror which has an order-blocking filter in front of it, so that the light is reflected off the front surface of the filter rather than the mirror itself. MIRRORB attenuates the image and is suitable for use with bright objects.