Spectral line shifts were determined for a number of telescope pointings
relative to the line position at zenith. The set-up comprised Grism #8
with 0.7" slit and unbinned pixels. Three exposures of helium arc lamp
spectra were taken at each position except at zenith where 4 sets of 3
exposures each were taken. The results are plotted below.
- Each consecutive circle represents 15 degrees of zenith distance.
- The location of a box represents the corresponding telescope pointing.
- The numbers within a box represent the shift, mean value (upper line) and rms (lower line), in the spectrum between that position and zenith