Found 11 talks width keyword atmospheric effects

The new generation of spectrometers designed for extreme precision radial velocities enable correspondingly precise stellar spectroscopy. It is now fruitful to theoretically explore what the information content would be if stellar spectra could be studied with spectral resolutions of a million or more, and to deduce what signatures remain at lower resolutions. Hydrodynamic models of stellar photospheres predict how line profiles shapes, asymmetries, and convective wavelength shifts vary from disk center to limb. Corresponding high-resolution spectroscopy across spatially resolved stellar disks is now practical using differential observations during exoplanet transits, thus enabling the testing of such models. A most demanding task is to understand and to model spectral microvariability toward the radial-velocity detection of also low-mass planets in Earth-like orbits around solar-type stars. Observations of the Sun-as-a-star with extreme precision spectrometers now permit searches for spectral-line modulations on the level of a part in a thousand or less, feasible to test against hydrodynamic models of various solar features.

Durante el presente seminario hablaremos sobre el estado actual del banco óptico GTCAO. Se hará énfasis en las tareas mecánicas en curso referentes a las instalaciones auxiliares para la integración y comisionado del banco, planteando problemáticas generales de las tareas y soluciones adoptadas.

Enlace Youtube: https://youtu.be/4WTGKMGwd7o

In this talk, I will start by briefly presenting the Institut d'Optique Graduate School and the Laboratoire Charles Fabry, where I conduct my research. Then I will explain the principle of adaptive optics and discuss some issues related to the control of AO systems. This will lead to the general ideas behind high-performance control. In particular, I will explain why high-performance control can outperform the standard integrator. Some results of on-sky experiments will be shown, and I will conclude the talk by presenting our PhD students working through research collaborations.

Al objeto de incrementar la cobertura de cielo proporcionada por el sistema de óptica adaptativa de GTC, durante los últimos 4 años se ha estado trabajando en la incorporación de un sistema de estrella guía láser de Sodio. A través de esta charla se repasará el estado actual del proyecto enfatizando aquellos aspectos relacionados con el sistema óptico de lanzamiento de la estrella guía. 

The precipitable water vapour (PWV) is the main absorber in the Earth's
atmosphere at infrared (IR) and microwave wavelengths. In the last years,
the IAC Sky team has been providing real-time PWV data from a monitor based
on the GNSS (GPS) technique (GNSS PWV Monitors; GPM). Among other things,
the PWV values help in the scheduling of the telescopes with IR
instrumentation. The GPM have undergone a continuous process of upgrading.
More recently, we have undertaken the PWV forecasting. We will present in
the talk a brief summary of the monitors and details of ForO ("Forecasting
the Observatories"), the forecasting system for PWV at the Observatories.
ForO is based on a mesoscale Numerical Weather Prediction (NWP) model. The
ForO system has been validated and calibrated with PWV data from the GPM
and will deliver accurate PWV daily predictions for ORM and OT on a 24, 48
and 72 hours windows. This is a definitive improvement to optimize the
flexible scheduling for IR observations, in particular for CanaryCAM and
EMIR at the GTC.

In the past years, intensive Site Characterization campaigns have been performed to chose the sites for the future giant ELTs. Various atmospheric turbulence profilers with different resolution and sensed altitude ranges have been used, as well as climatological tools and satellite data analysis. Mixing long term statistics at low altitude resolution with high resolution data collected during short term campaigns allows to produce the reference profiles as input to the Adaptive Optics (AO) instrument performance estimators. In this talk I will perform a brief review of the principal and most used instruments and tools in order to give to the audience a panorama of the work and the efforts to monitor the atmospheric turbulence for astronomical purposes.

An analysis of the impact of seismic and volcanic activity was carried out at selected astronomical sites, namely the observatories of El Teide (Tenerife, Canary Islands), Roque de los Muchachos (La Palma, Canary Islands), Mauna Kea (Hawaii) and Paranal (Chile) and the candidate site of Cerro Ventarrones/Armazones (Chile). In this sense, we studied the impact of seismicity, volcanic ash clouds, lava flows and ground deformation. Hazard associated with volcanic activity is low or negligible at all sites, whereas seismic hazard is very high in Chile and Hawaii. The lowest geological hazard in both seismic and volcanic activity was found at Roque de los Muchachos observatory, in the island of La Palma.

There are many parameters accounting for the quality of an astronomical site, namely seeing, cloud cover, ground winds, high-altitude winds, etc. The water vapor content is the main parameter affecting the IR quality of astronomical sites. The fraction of nights with good IR conditions (small column of water vapor) as a function of the epoch of the year will allow an optimal scheduling of telescope observing time. Global Positioning System (GPS) is an increasingly operational tool for measuring the precipitable water vapor (PWV). In this seminar, we briefly describe the procedure to estimate the PWV through GPS and we present the statistical results derived from a 7.5-year long time series of PWV estimations derived from GPS at the Roque de los Muchachos Observatory.