A cryogenic dithering stage for moving SPHERE-IRDIS' detector

Rohloff, Ralf-Rainer; Blümchen, T.; Feldt, M.; Naranjo, V.; Ramos, J.; Müller, K.‐H.; Marth, H.; Pertsch, P.; Dohlen, Kjetil

doi:10.1117/12.788839

Cited by 4 publications

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“…To improve the flat-field accuracy from 0.5% to 0.1%, both instruments have the possibility of dithering their detector in the focal plane on a square grid of a few pixels (up to 10), by steps of one pixel. By this procedure, the scientifically useful signal falls on different physical pixels throughout the observing sequence, which results in averaging flat-field variations after the images are aligned and combined during the data analysis (Rohloff et al 2008). For IRDIS, the improvement in flat field accuracy is expected to play a role in small separations ( < ∼ 0.…”

Section: Acquisition Of the Data In Laboratorymentioning

confidence: 99%

Performance of the VLT Planet Finder SPHERE

Zurlo

Vigan

Mesa

et al. 2014

A&A

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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.

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Section: Acquisition Of the Data In Laboratorymentioning

confidence: 99%