ESO adaptive optics facility progress report

Abstract

The ESO Adaptive Optics Facility (AOF) consists in an evolution of one of the ESO VLT unit telescopes to a laser driven adaptive telescope with a deformable mirror in its optical train.The project has completed the procurement phase and several large structures have been delivered to Garching (Germany) and are being integrated (the AO modules GRAAL and GALACSI and the ASSIST test bench). The 4LGSF Laser (TOPTICA) has undergone final design review and a pre-production unit has been built and successfully tested. The Deformable Secondary Mirror is fully integrated and system tests have started with the first science grade thin shell mirror delivered by SAGEM. The integrated modules will be tested in stand-alone mode in 2012 and upon delivery of the DSM in late 2012, the system test phase will start. A commissioning strategy has been developed and will be updated before delivery to Paranal. A substantial effort has been spent in 2011-2012 to prepare the unit telescope to receive the AOF by preparing the mechanical interfaces and upgrading the cooling and electrical network. This preparation will also simplify the final installation of the facility on the telescope.A lot of attention is given to the system calibration, how to record and correct any misalignment and control the whole facility. A plan is being developed to efficiently operate the AOF after commissioning. This includes monitoring a relevant set of atmospheric parameters for scheduling and a Laser Traffic control system to assist the operator during the night and help/support the observing block preparation.

Latitudinal variation in the abundance of methane (CH4) above the clouds in Neptune's atmosphere from VLT/MUSE Narrow Field Mode Observations

“…The Multi Unit Spectroscopic Explorer (MUSE) instrument (Bacon et al 2010) at ESO's Very Large Telescope (VLT) in Chile is an integral-field spectrograph, which records 300 × 300 pixel 'cubes', where each pixel, or 'spaxel', contains a complete visible/nearinfrared spectrum (0.48 -0.93 µm) with a spectral resolving power of 2000 -4000. MUSE has two viewing modes: a Wide-Field Mode (WFM) with a 60 × 60 field of view (FOV) and a Narrow-Field Mode (NFM), with a 7.5 × 7.5 FOV (giving a pixel size of 0.025 ), which utilises Adaptive Optics (Arsenault et al 2012;Ströbele et al 2012) to improve the spatial resolution to < 0.1 . At such a spatial resolution it is important to correct for differential atmospheric refraction between different wavelengths, for which MUSE utilises an atmospheric dispersion compensator that reduces residual shifts between wavelengths to less than a pixel.…”

Astrophotonics: astronomy and modern optics

“…Output powers of 50 W at the sodium line wavelength were achieved by combining interferometrically three Raman fiber lasers at 1178 nm (Taylor et al 2010). The system engineered by TOPTICA includes several servo systems enabling a power stability better than 2% over several hours and a fully maintenance-free operation (Arsenault et al 2012). Four units of the laser sources are currently forming the laser guide star asterism of the LGS facility at the UT4 VLT (Calia et al 2004), which feeds the GRAAL/HAWK-I (Paufique et al 2012) and the GALACSI/MUSE (Ströbele et al 2012;Laurent et al 2010) instruments.…”

MUSE narrow field mode observations of the central kinematics of M15

“…Two of the pointings were observed for 5×250 s; the remaining two 4 × 250 s. The DIMM seeing ranged from 0.5 to 1.2 arcsec. The observations were all carried out using the GALACSI adaptive optics module (Arsenault et al 2012;Ströbele et al 2012) which provides MUSE a 7.5 by 7.5 arcsec field-of-view with a spatial sampling of 0.025 arcsec in NFM. In nominal mode, MUSE provides wavelength coverage between 4800 Å and 9300 Å with a gap between 5780 and 6050 Å due to the notch filter used to suppress the light from the laser guide stars.…”