Forecasting water vapour above the sites of ESO's Very Large Telescope (VLT) and the Large Binocular Telescope (LBT)

Water vapour in the atmosphere is the main source of the atmospheric opacity in the infrared and sub-millimetric regimes and its value plays a critical role in observations done with instruments working at these wavelengths on ground-based telescopes. The scheduling of scientific observational programs with instruments such as the VLT Imager and Spectrometer for mid Infrared (VISIR) at Cerro Paranal and the Large Binocular Telescope Interferometer (LBTI) at Mount Graham would definitely benefit from the ability to forecast the atmospheric water vapour content. In this contribution we present a study aiming at validating the performance of the non-hydrostatic mesoscale Meso-NH model in reliably predicting precipitable water vapour (PWV) above the two sites. For the VLT case we use, as a reference, measurements done with a Low Humidity and Temperature PROfiling radiometer (LHATPRO) that, since a few years, is operating routinely at the VLT. LHATPRO has been extensively validated on previous studies. We obtain excellent performances on forecasts performed with this model, including for the extremely low values of the PWV (<= 1 mm). For the LBTI case we compare one solar year predictions obtained with the Meso-NH model with satellite estimates again obtaining an excellent agreement. This study represents a further step in validating outputs of atmospheric parameters forecasts from the ALTA Center, an operational and automatic forecast system conceived to support observations at LBT and LBTI.Comment: 15 pages, 8 figures, 11 tables, MNRAS accepted on 28 November 201

The Physical Model in Action: Quality Control for X-Shooter

The data reduction pipeline for the VLT 2nd generation instrument X-Shooter uses a physical model to determine the optical distortion and derive the wavelength calibration. The parameters of this model describe the positions, orientations, and other physical properties of the optical components in the spectrograph. They are updated by an optimisation process that ensures the best possible fit to arc lamp line positions. ESO Quality Control monitors these parameters along with all of the usual diagnostics. This enables us to look for correlations between inferred physical changes in the instrument and, for example, instrument temperature sensor readings.Comment: 9 pages, 8 figures, style files included, Proc. of Observatory Operations: Strategies, Processes, and Systems III, eds. D.R. Silva, A.B. Peck, B.T. Soifer, SPIE 7737, 1

Study of the atmospheric conditions at Cerro Armazones using astronomical data

Aims: We studied the precipitable water vapour (PWV) content near Cerro Armazones and discuss the potential use of our technique of modelling the telluric absorbtion lines for the investigation of other molecular layers. The site is designated for the European Extremely Large Telescope (E-ELT) and the nearby planned site for the Cherenkov Telescope Array (CTA). Methods: Spectroscopic data from the Bochum Echelle Spectroscopic Observer (BESO) instrument were investigated by using line-by-line radiative transfer model (LBLRTM) radiative transfer models for the Earths atmosphere with the telluric absorption correction tool molecfit. All observations from the archive in the period from December 2008 to the end of 2014 were investigated. The dataset completely covers the El Nino event registered in the period 2009-2010. Models of the 3D Global Data Assimilation System (GDAS) were used for further comparison. Moreover, for those days with coincidence of data from a similar study with VLT/X-shooter and microwave radiometer LHATPRO data at Cerro Paranal, a direct comparison is presented. Results: This analysis shows that the site has systematically lower PWV values, even after accounting for the decrease in PWV expected from the higher altitude of the site with respect to Cerro Paranal, using the average atmosphere found with radiosondes. We found that GDAS data are not a suitable method for predicting of local atmospheric conditions - they usually systematically overestimate the PWV values. Due to the large sample, we were furthermore able to characterize the site with respect to symmetry across the sky and variation with the years and within the seasons. This kind of technique of studying the atmospheric conditions is shown to be a promising step into a possible monitoring equipment for CTA.Comment: Accepted for publication in Astronomy and Astrophysics, 7 pages, 9 figure

Towards formal analysis of insider threats for auctions

This paper brings together the world of insider threats and auctions. For online-auction systems, like eBay, but also for high-value one-off auction algorithms as they are used for selling radio wave frequencies, the use of rigorous machine supported modelling and verification techniques is meaningful to prove correctness and scrutinize vulnerability to security and privacy attacks. Surveying the threats in auctions and insider collusions, we present an approach to model and analyze auction protocols for insider threats using the interactive theorem prover Isabelle. As a case study, we use the cocaine auction protocol that represents a nice combination of cryptographic techniques, protocols, and privacy goals suitable for highlighting insider threats for auctions