Executive summary
Release content:
For all 98 tiles completed (i.e. the final observations were obtained) between 1 October 2012 and 1 October 2013 the following data products:
- Coadds: photometrically and astrometrically calibrated, stacked images (1 per filter per tile)
- Weights: weight frames (1 for each Coadd)
- Flag images: FITS images with pixel flags in areas affected by bright stars, saturated pixels, reflections, and other artefacts (1 for each Coadd)
- Source lists: lists of sources detected in single Coadds
For all 148 tiles released in KiDS-ESO-DR1 and KiDS-ESO-DR2:
- a multi-band, aperture-matched source catalog
Data quality:
PSF size and ellipticity distributions and achieved limiting magnitudes can be summarized as follows:
Filter | PSF FWHM (arcsec) | PSF ellipticity | Limiting mag (2'' 5σ AB) |
---|---|---|---|
u | <1.2 | ~0.04 | ~24.3 |
g | <1.0 | ~0.05 | ~25.1 |
r | <0.85 | ~0.05 | ~24.9 |
i | <1.2 | ~0.05 | ~23.7 |
Photometric calibration:
The photometric calibration is in AB magnitudes in the instrumental photometric calibration. Tiles are photometrically homogenized by tying stellar photometry between the dithers and overlapping CCDs together; the resulting photometry is flat to typically within 2% over the full square degree FOV. Absolute photometry is done per tile and based on nightly zeropoints based on SA field observations.
Astrometric calibration:
Global solutions are calculated for each tile, spanning all dithers and CCDs, with 2MASS used as reference catalog. The 2-dimensional RMS of source positions between the dithers is typically 0.03 arcseconds.
Bright star and defects masking:
Flag images are provided with pixel flags indicating regions affected by saturated pixels, diffraction spikes, reflection halos, and other (manually masked) defects.
Source lists:
Single-band source lists are extracted from the Coadds. The source lists provide for
each detected source several magnitude measurements, a large number of aperture fluxes,
star/galaxy classification, and masking flags.
The typical 98% completeness magnitudes for the 4 filters are
22.8 in u, 24.0 in g, 23.9 in r, and 22.5 in i.
Multi-band catalog
The multi-band catalog is based on source detection in the r-band. For all sources a number of aperture fluxes, S/G separation, and masking flags are provided. Furthermore, Gaussian Aperture Photometry and aperture-corrected fluxes are provided to account for seeing differences between filters. The typical 98% completeness measured in the r-band is 23.9 mag.
Data access:
Data products can be accessed via:
Relevant links:
- KiDS DR1 and DR2 paper: in preparation
- The Kilo-Degree Survey: paper in Experimental Astronomy
- Astro-WISE optical image pipeline: paper in Experimental Astronomy