We have seen in previous sections the importance of having artificial sources of lines that produce a strong enough flux and that can be arranged facing the entrance of the telescope for adjustments. In routine use these same lamps can be used to calibrate scientific spectra in wavelength (illumination the full entrance of the telescope is best). It is recommended to have two types of inexpensive lamps: (1) a compact fluorescent lamp (but beware that legislation in Europe mean that these are disappearing, replaced by the calamitous LED lamp, but by looking hard we can still find them.), (2) a neon discharge lamp that can often be found from electrical control systems, for example.

Here are the wavelengths of the main lines that can be identified in the light produced by a compact fluorescent lamp (the fine lines come from a mercury vapor, the broad bands come from the rare earths terra deposited on the inner side of the glass bulb):

A line atlas of a neon lamp (Ne) :

For information, stellar Balmer lines, which are very useful for calibrating UVEX spectra in the ultraviolet:

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