filtering reference spectrum

Forums Spectroscopy ALHENA WITH A STARANALYSER filtering reference spectrum

Robin Leadbeater

Hi Hugh,

If there is a big disparity between the resolution of the measured and ref spectra I find it is useful to apply a (typically spline) filter one of them to match the resolution before doing the division as that (along with slightly wavelength shifting them as necessary) makes editing any remaining artifacts out of raw instrument response easier. It did not work perfectly in Peter’s case as typically the Star Analyser resolution varies along the spectrum but attached is an example of the division with and without filtering with my very low resolution ALPY 200 and the MILES reference spectrum.  It is also useful in high resolution spectra using the LHIRES where the line profile of a ref star like Vega for example can take up most of the width of the spectrum. Here I did the smoothing manually in VSpec but the response function in ISIS  has both filtering and offset adjustment capability built in to the response function calculator.