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Conclusions

The solution of the problems regarding the non-standard ESO-WFI image headers is a very important issue that must be taken into account for the implementation of any software of any wide field imager. This will be particularly important for OmegaCam, the 32-CCD mosaic camera that will be installed at the VST.

The photometric inhomogeneity of the ESO-WFI, attributed, at least in part, to an additional-light pattern due to internal reflections off the telescope corrector, may yield photometric errors of up to 3% in the B V R I broad-bands and up to 5% in the medium-band filters. This problem shall be solved in the near future using calibration images (flat and standard fields). Another possibility for reducing the photometric errors is to derive independent zero points for each CCD of the mosaic. This solution requires larger and denser standard fields than those currently available in the literature. Although the ongoing project by Stetson et al. (2000) is actually increasing the number of standard stars in the Landolt fields from a few tens to a few hundreds, the areas covered and the density of standards still do not appear to be sufficient for the new generation of wide-field imagers that will be operative in the next years. Our absolute astrometric accuracy, of the order of 0.3'', is limited by the intrinsic accuracy of the reference catalogue used (USNO in our case). The use of new astrometric catalogues will improve the relative astrometric accuracy, from $\sim$0.15 to less than 0.1''. These numbers will be sufficient to match the technical requirements of the new generation multi-fibre instruments, such as those mounted at the VLT.

The extraction of the OACDF source catalogues is currently ongoing and plans for follow-up studies and for cross-correlation with other surveys obtained at different wavelengths, from X-rays to radio wavelengths, are already in progress. The multi-colour database extracted OACDF represent a power-full database to identify and study medium reach cluster at intermediate redshifts as shown by our first results.


next up previous
Next: Appendix A: superflat and Up: The Capodimonte Deep Field Previous: Galaxy Cluster identification
Juan Alcala
2002-02-05