The MICADO first light imager for ELT: its astrometric performance

Authors :: Pott, J. -U.
Rodeghiero, G.
Riechert, H.
Massari, D.
Fabricius, M.
Arcidiacono, C.
Davies, R. I.
Publication Year :: 2018
Abstract: We report on our ongoing efforts to ensure that the MICADO NIR imager reaches differential absolute (often abbreviated: relative) astrometric performance limited by the SNR of typical observations. The exceptional 39m diameter collecting area in combination with a powerful multi-conjugate adaptive optics system (called MAORY) brings the nominal centroiding error, which scales as FWHM/SNR, down to a few 10 uas. Here we show that an exceptional effort is needed to provide a system which delivers adequate and calibrateable astrometric performance over the full field of view (up to 53 arcsec diameter).<br />Comment: 5 pages, submitted to SPIE 2018 Astronomical Telescopes + Instrumentation