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ESPaDOnS: instrument details and configurations http://webast.ast.obs-mip.fr/magnetisme/espadons_new/configs.html
Instrument configurations
To keep ESPaDOnS as simple as possible, it has been designed as a ’point and shoot’ instrument with very few different
configurations. Only three choices are available:
a spectropolarimetric mode in which the two orthogonal states of a given polarisation - either circular (Stokes V) or
linear (Stokes Q or U) - are recorded throughout the whole spectral range; the two spectra are recorded simultaneously
on the ccd detector with the two sets of orders interleaved; the two fibre images are sliced in 3 at spectrograph entrance,
yielding an average spectral resolution of about 68,000;
a first spectroscopic mode (called ’object+sky’) in which the spectra of the star and of the background sky are
recorded simultaneously on the ccd detector (with orders interleaved); again, the two fibre images are sliced in 3 at
spectrograph entrance, and the average spectral resolution is about 68,000;
a second spectroscopic mode (called ’object only’) in which we only collect the spectrum from the star and neglect
that from the background sky (for objects bright enough to outshine the sky background); in this case, the single fibre
image is sliced in 6 at spectrograph entrance, bringing the average spectral resolution to about 81,000.
© Jean-François Donati, last update May 18 2004
3 of 3 08/07/04 11:28 PM