A continuum lamp, He-Ar lamp, and Fe-Ne source are
available for spectral calibration [X]. They can be controlled either
manually or remotely by computer.
In order to adjust the intensity to safe levels and to spectrally
compensate a lamp's output, each lamp housing contains a filter access
which can hold up to two 
--in. filters (neutral
density or otherwise) in standard Steward filter holders (see Chapter 7).
Make sure the acquisition TV (Chapter 5.1) is turned down when using
the calibration lamps!
Note that the Fe-Ne lamp may take a good fraction of a minute to warm up, depending on ambient temperature. Exercise caution and use a neutral density filter or filters in front of this lamp to obtain a proper exposure.
An atlas of comparison lamp spectra is provided as Appendix B.