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The main scientific objective of the SPHERE instrument at VLT (Spectro-Polarimetric High-contrast Exoplanet REsearch) is to detect and characterize, using direct imaging techniques, young giant exoplanets orbiting around nearby stars. This instrument also allows to detect and characterize disks around young stars in which planet forms. This is a huge challenge since these planets lie very close to their host star and have a much smaller luminosity (typically 100000 times less than their host star). SPHERE combine several advanced techniques (extreme adaptive optics, coronagraphy, differential imager and spectro-imager in the visible and near infrared) and include three scientific instruments : IRDIS (differential imaging and polarimetry in the infrared), IFS (field spectrograph in the infrared), and ZIMPOL (differential polarimetric imaging in the visible).
SPHERE data reduction in short
Our pipeline basic reduction draws on the ESO public pipeline supplemented by several IDL/Python routines improving the quality of the reduction and the ability to deal with poor/heterogeneous dataset. For the SPHERE data, we provide data corresponding to level 0 to 3. We also calibrate the data in wavelength, flux and astrometry and present the outputs of these basic reduction steps (’Level 1 data’) as 4D datacubes (x,y,nframes, lambda) as commonly used in high contrast imaging. We also propose a complete ADI and/or SDI reduction (’Level 2 data’) using several different algorithms from the SpeCal routine set (Galicher et al. 2018). Level 3 has been obtained by the SPHERE consortium for the SHINE survey only since it does request a large amount of human intervention and is not automatized yet. Note that the SHINE survey is also available in the survey section below. See the data processing page and our manual LIEN for more informations.
The different steps are XXXDECIDERSI ON REPORTE CE PARAGRAPHE DANS PAGE PROCESSING PROTOCOLEXXX :
- The ESO DRH pipeline
- Bad pixels and background crosstalks routines (IFS)
- Wavelength solution correction (IFS)
- PCA subtraction to a data cube (IFS, IRDIS)
- Conversion of data cubes in organized data cubes, parallactic angles corrected for the true north and wavelength calibration for each canal (IFS, IRDIS)
- Automatic and/or manual frame selection routines (IFS, IRDIS)
- Images processed with different algorithms depending on observing conditions : detection limits, photometry and astrometry of point sources (available soon)
Level 2 data includes residual maps after ADI or ASDI processing. If using the DIVA+ interface to request the data, the used algorithm can be identified in the field “reduction_information”. If using the processing center client, they can be identified by the field “Reference” in the process brower when using the client (see FAQ) and in the directories after retrieval. They are :
- NoADI : simple stacking of the master cubes
- cADI : Classical Angular Differential Imaging (Marois et al. 2006, Lafrenière et al 2007)
- TLOCI : Flavor of Angular Differential Imaging based on Locally Optimised Combination of Images (Marois et al. 2011, Galicher et al 2018)
- PCA : Flavor of Angular Differential Imaging based on Principal Component Analysis
Supported modes as of February 2024
| Instrument | Supported modes | Mode support in progress | Mode not supported yet |
|---|---|---|---|
| IFS | ALL modes, ADI/ASDI | – | – |
| IRDIS | Single and dual-band imaging ADI/ASDI | Polarimetry | LSS ; SAM |
| ZIMPOL | – | All modes (intensity and polarimetry) | – |
The SPHERE reduced data cover most of P95-P104, i.e. 5 years of observations. They represent XXXX targets, composed mainly of stars (XXXX), but also solar system objects, AGN and stellar clusters. METTRE ICI QQUES STATS ISSU DU TRAVAIL DE STEPHANE
SPHERE data releases as of February 2024
| Reduced and available | Reduction in progress | Estimate of future releases | |
|---|---|---|---|
| Day time calibrations | All IRDIS/IFS existing calibrations are available | Calibrations from yesterday | Automatically up-to-date with at most 48hrs delay |
| IRDIS/IFS ESO periods | SVT ; P95-P104 | >P106 | 2024-2025 |
| Corresponding dates | 2014-10-01 to 2020-03-31 | ||
| ZIMPOL reductions | No ZIMPOL data | P95-P98 | 2024 |
| Other comments | Some SVT and commissioning data not reduced | – | – |
Data access: Levels 2 and 3 are available on DIVA+. All levels are available through the client. More details here.
The Direct Imaging Virtual Archive, DIVA, is dedicated to high-contrast imaging surveys, and more particularly to the main high-level science products (HLSP) of these surveys, such as detection limits and position of candidates. The data from these surveys have been reduced by the scientific teams indicated below (for the SPHERE/SHINE survey, our data processing center has been strongly involved, especially up to level 2 data). The survey data correspond to level 2 data (the list of available frame depends on the survey and is indicated below: PSF image, reduced image, detection limit, sensitivity map) and level 3 data (candidates) for some of those surveys. Through the DIVA+ archive, you can either access a survey as a single large file, or request data corresponding to individual targets from those dedicated surveys like for some SPHERE data. The data have been converted to HCI-FITS files (see format page).
16 surveys are currently available. The data have been obtained with various instruments: VLT/NACO, HST/NICMOS, VLT/SDI, MMT/SDI, Gemini North/NIRI, Gemini/NIRI, Spitzer/IRAC , Keck II/NIRC2/, Keck II/NIRI,Gemini South/NICI, SPHERE (first release of the SHINE survey)