Formaldehyde, H2CO, has been detected in the atmosphere at 2807 and 2869 cm−1 using high resolution infrared absorption spectroscopy from a ground based station. An order of magnitude measure of the column concentration (5 × 1015 molecules per cm²) is given, and an estimate of the trospospheric and stratospheric concentrations is derived from the line pressure broadening.

The vertical profile and total column concentration of HCl have been measured from ground based high resolution infrared absorption spectra. The lines recorded were the R1 and P5 of HCl35 at 2942.731 cm−1 and 2775.760 cm−1 respectively. Vertical profiles and column concentrations are reported for different seasons. Measurements indicate an HCl volume mixing ratio equal to (2.2 ± 0.5) × 10−11 at 10 km increasing to (3.4 ± 0.6) × 10−9 at 33 km.

HARMONI is the first light visible and near-IR integral field spectrograph for the ELT covering a large spectral range from 450nm to 2450nm with resolving powers from 3500 to 18000 and spatial sampling from 60mas to 4mas. It can operate in two Adaptive Optics modes -SCAO and LTAO -or with no AO. The project is preparing for Final Design Reviews. The laser Tomographic AO (LTAO) system provides AO correction with very high sky-coverage thanks to two systems: the Laser Guide Star Sensors (LGSS) and the Natural Guide Star Sensors (NGSS). LGSS is dedicated to the analysis of the wavefront coming from 6 laser guide stars created by the ELT. It is made of 6 independent wavefront sensor (WFS) modules mounted on a rotator of 600mm diameter to stabilise the pupil onto the microlens array in front of the detector. The optical design accepts elongated spots of up to 16 arcsec with no truncation using a CMOS detector from SONY. We will present the final optical and mechanical design of the LGSS based on freeform lenses to minimize the numbers of optical components and to accommodate for the diversity of sodium layer configurations. We will focus on rotator design, illustrating how we will move 1 tons with 90" accuracy in restrictive environment. Finally, we will present the strategy to verify the system in HARMONI context. The main challenge for the verification being how to test an AO system without access to the deformable mirror, part of the ELT.

Nous avons enregistré les spectres de O3 élargis par O 2 et par l'air sec dans la région de 5 μm, à des températures variant de 296 K à 171 K. Nous en déduisons la valeur des coefficients d'élargissement à ces diverses températures. Ecrivant que αL0( T) = αL0(T0)·(T0/T) n nous en déduisons n = 1,3 ± 0,2 pour l'air

We describe the design, construction and characterisation of a collimated, dual-species oven source for generating intense beams of lithium and caesium in UHV environments. Our design produces full beam overlap for the two species. Using an aligned microtube array the FWHM of the output beam is restricted to ∼ 75 milliradians, with an estimated axial brightness of 3.6×10 14 atoms s −1 sr −1 for Li and 7.4×10 15 atoms s −1 sr −1 for Cs. We measure the properties of the output beam using a spatially-resolved fluorescence technique, which allows for the extraction of additional information not accessible without spatial resolution.