The Compact Fluorescent Light (CFL) is an effective and cheap calibration light source for spectrometers - recently I discovered a source of 12V bulbs which has allowed me to make safe effective lights for portable use in the field. I have attached a version of the spectrum of a CFL bulb I have generated to allow easy access to the information required for calibration, annotated with the wavelengths of the main lines. I am indebted to Wikipedia for the source information on which this is based. For comparison I also include an annotated solar spectrum, a comparison of the CFL with RELCO spectrum, and a couple of versions of LED spectra. The easy of the use of the CFL spectra becomes evident when looking at this selection of spectra, although the RELCO gives more lines and is more useful for high resolution spectrometer calibration. The solar spectrum has the right number of lines but is by definition not available at the time of day (or night) when we most need it! I have posted more information on my attempts at creating adequate calibration lights for spectroscopy on my club's blog here: It is worth noting that I have received advice on other topics on this forum that have recommended RELCO starter bulbs for calibration lights and I have created such a light and am in process of trying to identify the lines on that light - but further conversation on that will continue on those topics. For folks like me new to spectrometry, looking for an immediate calibration solution (even if not the best) the CFL bulbs provide a readily accessible solution. Andy   Spectrum of LED strip light 220918@1820 white-XAxisProjection.bmp