For many years the FORS2 instrument has suffered from artefacts in the flat fields caused by surface inhomogeneities on the longitudinal atmospheric dispersion corrector (LADC) that affected high-precision photometric and spectroscopic measurements. Recently, the FORS LADC prisms were exchanged, and our analysis of a large number of flat fields shows that this exchange has resulted in a significant decrease in the level of small-scale artefacts.
@article{arxiv.1603.03865,
title = {FORS2 Rotating Flat Field Systematics Fixed -- Recent Exchange of FORS LADC Prisms Improves the Long-known Flat-fielding Problem},
author = {Henri M. J. Boffin and Sabine Moehler and Wolfram Freudling},
journal= {arXiv preprint arXiv:1603.03865},
year = {2016}
}
Comments
2 pages; to appear in the March 2016 issue of the ESO Messenger