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The Neon spectrum between 3100 Å and 9600 Å can be roughly divided in three sections: very strong features due to NeI dominate the wavelength range 5850-7440 Å ; another group of prominent features are present between 7500 and 9600 Å , although these are as much as ten times fainter than those in the former range. Bluewards, neon lines, both NeI and NeII, appear only weakly, and the copper spectrum provides the strongest features. Even so, the strong copper line CuI 5105 Å is barely one-twentieth the intensity of the principal NeI lines described earlier.
This implies that for wavelength calibrations in the red, the copper-neon lamp is only really useful for low-dispersion work whilst the red features are so spaced that at high dispersion very few lines may be present in certain wavelength intervals. In the blue, at intermediate and high dispersions, it may be useful to supplement the argon spectrum in regions where this is a bit sparse e.g. 3300-4000 Å , but significantly longer exposures would be necessary to bring up the few NeII lines below 3250 Å . To reach a few weaker lines redward of 9700 Å, in particular in the region 1.0-1.1m, careful second-order filtering is required, and also considerable patience.
This lamp is normally located in position 2, enabled by the ADAM command 2LAMP ON.