It is commissioning time for the diffraction limited mode of LUCI2, the near infrared imager and multi-object spectrograph which saw first light in seeing-limited mode back in November 2013.
Much work was performed during day time on the NCPA (non-common path aberrations) correction starting on January 19, 2015, to be ready for the first night of on-sky observing on January 26. Unfortunately, clouds and snow falls were followed on the 27th by yet another overcast night.
On the night of the 28th, a 2-hr gap of clear sky between waves of heavy clouds led to first light on LUCI2 in AO mode. With a seeing of about 1arcsec, the loop on the bright star HIP 15925 (6th mag) was closed the star imaged with LUCI2 and the FLAO system working with NCPA correction in HeI (1.1µm), FeII (1.6µm), and Br_gamma (2.2µm) filter bands.
The Strehl ratios achieved at first light were 45% at 1.1µm, 75% at 1.6 and 2.2µm wavelength (see a very preliminary analysis on the pictures below), a tribute to the quality of the preparatory daytime work!
There is obviously much work ahead over the next months to get the system ready for regular observations, but these first results augur well for the final performance of LUCI2 in diffraction-limited mode, and eventually of LUCI1 once equipped with its AO-compatible camera toward the end of the year!
LUCI2-AO commissioning work is led by W. Seifert (LUCI) and S. Esposito (AO)