Accurate Sky Continuum Subtraction with Fibre-fed Spectrographs
/ Authors
Yanbin Yang Myriam Rodrigues Mathieu Puech Hector Flores Gepi, Observatoire de Paris, Cnrs, U. Diderot, Meudon, France Eso Observatorio do Valongo, Brazil Supa, Institute for Astronomy, U. Edinburgh, Royal Observatory of Edinburgh
and 6 more authors
UK Astronomy Technology Centre, UK Inaf, Osservatorio Astronomico di Roma, Italy Cavendish Laboratory, U. Cambridge, UK.
/ Abstract
Fibre-fed spectrographs now have throughputs equivalent to slit spectrographs. However, the sky subtraction accuracy that can be reached has often been pinpointed as one of the major issues associated with the use of fibres. Using technical time observations with FLAMES-GIRAFFE, two observing techniques, namely dual staring and cross beam-switching, were tested and the resulting sky subtraction accuracy reached in both cases was quantified. Results indicate that an accuracy of 0.6% on sky subtraction can be reached, provided that the cross beam-switching mode is used. This is very encouraging with regard to the detection of very faint sources with future fibre-fed spectrographs, such as VLT/MOONS or E-ELT/MOSAIC.