Performance of the VLT Planet Finder SPHERE

Abstract

Context. The new planet finder for the Very Large Telescope (VLT), the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE), just had its first light in Paranal. A dedicated instrument for the direct detection of planets, SPHERE, is composed of a polametric camera in visible light, the Zurich IMager POLarimeter (ZIMPOL), and two near-infrared sub-systems: the Infra-Red Dual-beam Imager and Spectrograph (IRDIS), a multi-purpose camera for imaging, polarimetry, and long-slit spectroscopy, and the integral field spectrograph (IFS), an integral field spectrograph. Aims. We present the results obtained from the analysis of data taken during the laboratory integration and validation phase, after the injection of synthetic planets. Since no continuous field rotation could be performed in the laboratory, this analysis presents results obtained using reduction techniques that do not use the angular differential imaging (ADI) technique. Methods. To perform the simulations, we used the instrumental point spread function (PSF) and model spectra of L and T-type objects scaled in contrast with respect to the host star. We evaluated the expected error in astrometry and photometry as a function of the signal to noise of companions, after spectral differential imaging (SDI) reduction for IRDIS and spectral deconvolution (SD) or principal component analysis (PCA) data reductions for IFS. Results. We deduced from our analysis, for example, that β Picb, a 12 Myr old planet of ∼10 M Jup and semi-major axis of 9-10 AU, would be detected with IRDIS with a photometric error of 0.16 mag and with a relative astrometric position error of 1.1 mas. With IFS, we could retrieve a spectrum with error bars of about 0.15 mag on each channel and astrometric relative position error of 0.6 mas. For a fainter object such as HR 8799d, a 13 M Jup planet at a distance of 27 AU, IRDIS could obtain a relative astrometric error of 3 mas.

The LEECH Exoplanet Imaging Survey. Further constraints on the planet architecture of the HR 8799 system

“…This error could be reduced using the adaptive secondary mirror to create several faint replica of the star at a given separation in the field of view in order to accurately derive the star center (Marois et al 2006b;Sivaramakrishnan & Oppenheimer 2006). The use of star replica for estimating the center of coronagraphic or saturated images is employed in the new high-contrast imaging instruments SPHERE (Beuzit et al 2012;Zurlo et al 2014;Mesa et al 2015) and GPI (Macintosh et al 2014). On-sky tests are foreseen in the coming months to implement this technique for the LEECH observations.…”

New spectro-photometric characterization of the substellar object HR 2562 B using SPHERE

“…On the other hand, for IFS observations the reduction steps include: dark and flat-filed correction, definition of the spectral positions, wavelength calibration, and the application of the instrumental flat. For IFS we then apply on the wavelengthcalibrated datacubes (each of them composed by 39 monochromatic frames) the speckle subtraction exploiting the principal components analysis (PCA, Soummer et al 2012) as described in Mesa et al (2015) and Zurlo et al (2014). For what concerns IRDIS we performed the speckle subtraction with both PCA and TLOCI (Marois et al 2014), using the consortium pipeline (Galicher et al, in prep.…”

Multiple rings in the transition disk and companion candidates around RX J1615.3-3255

“…The observations were performed with the IRDIFS mode (Zurlo et al 2014) in pupil tracking, using IRDIS in dual-band imaging mode (Vigan et al 2010) in the H2H3 bands and IFS in Y J-band. The observations are taken with the Apodized pupil Lyot Coronagraph ALC_YJH_S, which has a diameter of 185 mas.…”