Exploring observations made with home spectrographs quantitatively using digital resources

In this work, we show a method to obtain wavelength calibrations from a standard source to be applied to spectra for which spectral lines are unknown, in order to use them in didactic activities involving homemade spectrographs. We present the instrumental setup used to obtain the calibration and the spectra of interest simultaneously. With the spectra, we show how to apply image processing techniques to treat, optimize and extract the data. For the calibration procedure we indicate how to search for the default values in the NIST spectral line database. An electronic spreadsheet was elaborated to obtain the spectra calibration by means of procedures using the DS9 software. We demonstrate the application of the calibration procedure in unidimensional and bidimensional spectra in the case of the helium vapor lamp spectrum with which we recover the wavelength of spectral lines with residues below 4 nm. Finally, we present suggestions for some practical didactic activities that can be conducted by means of the procedures exposed here using observations from everyday light sources.

Keywords
Physics teaching; astronomy teaching; spectra; quantitative approach