KiDS

KiDS
Name	KiDS
Caption	Kilo-Degree Survey footprint on the sky
Type	Astronomical survey
Operator	European Southern Observatory; Leiden Observatory; Argelander Institute for Astronomy
Location	Paranal Observatory; Cerro Paranal
Wavelength	Optical; near-infrared astronomy
Started	2011
Status	Completed / Ongoing data analysis

KiDS

KiDS is a wide-field optical imaging survey carried out with the VLT Survey Telescope at Paranal Observatory to map weak gravitational lensing and large-scale structure. The project combines deep multi-band imaging with precise image quality to constrain dark matter, dark energy, and structure formation alongside ancillary studies of galaxy evolution, quasars, and strong lensing. KiDS works in concert with major initiatives such as the VISTA Kilo-degree Infrared Galaxy survey, the Dark Energy Survey, and the Hyper Suprime-Cam Subaru Strategic Program to provide complementary coverage and cross-calibration.

Overview

KiDS was designed to deliver high-fidelity shape measurements for cosmic shear studies using the VLT Survey Telescope and its OmegaCAM instrument at Paranal Observatory, situated on Cerro Paranal. The survey footprint overlaps fields observed by the Sloan Digital Sky Survey, the Pan-STARRS project, and the Gaia mission to enable photometric and astrometric synergy. Project governance involves institutions such as Leiden Observatory, the University of Groningen, the University of Oxford, and the Max Planck Institute for Astronomy, with funding and collaboration from agencies like the European Research Council and national science foundations. KiDS strategy emphasizes control of systematic errors through repeat observations, coordinated calibration with VISTA and spectroscopic follow-up from facilities including the Very Large Telescope and the Anglo-Australian Telescope.

Survey Design and Instrumentation

The instrument suite centers on OmegaCAM mounted on the VLT Survey Telescope, offering a one-square-degree field with a mosaic of CCDs similar to detectors used by the Sloan Digital Sky Survey and the Dark Energy Camera. KiDS imaging uses multiple passbands comparable to SDSS's ugriz filters to enable photometric redshift estimation calibrated with spectroscopic samples from surveys like GAMA, BOSS, and VVDS. Observing strategy was optimized in coordination with scheduling at European Southern Observatory and employs seeing constraints comparable to those used by the Hyper Suprime-Cam program. Ancillary near-infrared data come from VISTA and the VIKING survey, while spectroscopic calibration leverages instruments such as VIMOS and AAOmega on the Anglo-Australian Telescope.

Data Processing and Calibration

KiDS data processing pipelines build upon algorithms and software developed in the context of projects like Astro-WISE, incorporating procedures comparable to those in Pan-STARRS and SDSS for bias subtraction, flat-fielding, and astrometric solution using reference catalogs such as Gaia and 2MASS. Photometric calibration links to standard star networks including those used by Landolt and the Stetson catalogs, while PSF modeling and shape measurement employ methods tested against challenges like the GREAT3 and GREAT10 blind shear tests. Quality control and mask generation follow practices used in the CFHTLS and the DES pipelines. The KiDS collaboration uses tomographic photometric redshift estimation calibrated against spectroscopic datasets from DEEP2, zCOSMOS, and VIPERS to mitigate biases in cosmological inference.

Scientific Results and Cosmology

KiDS results have produced constraints on the amplitude of matter fluctuations and the parameters of Lambda-CDM cosmology that have been compared with measurements from the Planck mission, the Atacama Cosmology Telescope, and the South Pole Telescope. Science outputs include cosmic shear tomography, galaxy–galaxy lensing, and cross-correlations with the Cosmic Microwave Background lensing maps from Planck and ACTPol. KiDS has reported measurements relevant to tensions in parameters like sigma_8 and S_8 when set against Planck 2015 and Planck 2018 results, stimulating follow-up by groups at the Max Planck Institute for Astrophysics, Institute for Astronomy, University of Edinburgh, and University of Cambridge. Beyond cosmology, KiDS has yielded catalogs of strong-lens candidates, discoveries of high-redshift quasars interpreted with spectroscopy from VLT instruments, and studies of galaxy morphology linked to surveys like HST imaging from the COSMOS field. Results have been disseminated in journals read by members of the International Astronomical Union and presented at conferences such as the American Astronomical Society meetings and the COSMO conferences.

Data Releases and Access

KiDS has published multiple public data releases coordinated with data centers such as the European Southern Observatory archive and the Leiden Observatory data portal, following precedents set by the Sloan Digital Sky Survey and the Hubble Space Telescope archives. Data products include calibrated images, catalogs of photometry and shape measurements, and value-added products like photometric redshift estimates cross-matched to GALEX, WISE, and VISTA catalogs. The project follows open-data practices adopted by the European Open Science Cloud framework, with provenance recorded similarly to metadata standards used by the Virtual Observatory and the International Virtual Observatory Alliance. User support and documentation mirror resources provided by the ESA and national data facilities.

Collaborations and Related Projects

KiDS maintains scientific partnerships with surveys and consortia including the VIKING survey on VISTA, the GAMA survey, the BOSS component of SDSS-III, and the DES collaboration for joint analyses. Methodological and algorithmic exchanges occur with initiatives like the HSC SSP, the Euclid preparation teams, and the LSST Science Collaborations to harmonize shear calibration and photometric redshift strategies. Institutional contributors include Leiden University, University of Durham, University of St Andrews, University of Bonn, and the Leibniz Institute for Astrophysics Potsdam, while funding and advisory links extend to agencies such as the Royal Society and the Netherlands Organisation for Scientific Research.

Category:Astronomical surveys