The fluorescent overhead lights should be on now. Place a white screen (either the 3x5
card or the larger cardboard) in front of the slit. Incline it at about 45 degrees so that
the overhead lights illuminate it, and light from the white screen goes to the slit.
To see something interesting here we need to change the wavelength of the
spectrometer. Set the central wavelength to 577 nm using the command
577. goto in the window of Seyon that controls the instrument. After it
has responded ``ok'',
take another 100 second exposure.
If all is working well you will see two bright lines in this spectrum. Save this frame too.