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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…

The Atacama desert stands as the most arid, non-polar, region on Earth and has accommodated a considerable portion of the world's ground-based astronomical observatories for an extended period. The comprehension of factors important for…

The Earth's turbulent atmosphere results in speckled and blurred images of astronomical objects when observed by ground based visible and near-infrared telescopes. Adaptive optics (AO) systems are employed to reduce these atmospheric…

Characterization of atmospheric turbulence is essential to understanding image quality of astronomical telescopes and applying adaptive optics systems. In this study, the vertical distributions of optical turbulence at the Peak Terskol…

In this paper we quantify the performances of an automated weather forecast system implemented on the Large Binocular Telescope (LBT) site at Mt. Graham (Arizona) in forecasting the main atmospheric parameters close to the ground. The…

In this study, the wind data series from five locations in Aegean Sea islands, the most active `hotspots' in terms of refugee influx during the Oct/2015 - Jan/2016 period, are investigated. The analysis of the three-per-site data series…

We present comprehensive seeing statistics for the San Pedro M\'artir site derived from the Thirty Meter Telescope site selection data. The observations were obtained between 2004 and 2008 with a Differential Image Motion Monitor (DIMM) and…

We examine the long-term time evolution (1965-2015) of the relationships between solar wind proton temperature (Tp) and speed (Vp) and between the proton density (np) and speed using OMNI solar wind observations taken near Earth. We find a…

For high contrast imaging systems, the time delay is one of the major limiting factors for the performance of the extreme adaptive optics (AO) sub-system and, in turn, the final contrast. The time delay is due to the finite time needed to…

Ground-based solar observations are severely affected by Earth's turbulent atmosphere. As a consequence, observed image quality and prevailing seeing conditions are closely related. Partial correction of image degradation is nowadays…

If ALPs exist, the refractive index of light will be modified when light traverses a region where an ALP field is present. We propose to measure the refractive index of light and its angular dependence as the Earth rotates with respect to…

This is the second article of a series devoted to European Extremely Large Telescope (E-ELT) site characterization. In this article we present the main properties of the parameters involved in high angular resolution observations from the…

As part of Saudi Arabia Vision 2030 and under the guidance of the Royal Commission for AlUla (RCU), efforts are underway to establish AlUla Manara as the Kingdom first major astronomical observatory. This study presents a preliminary…

An analysis of the tilt angles of the active regions in 15-24 activity cycles was performed. We used data from measurements of magnetic fields in the sunspot umbra in the period 1918 -2019 at the Mount Wilson Observatory, as well as the…

This work aims to choose potential astronomical sites that can be candidates for a new astronomical optical observatory in Ethiopia, in addition to the Entoto Observatory and Lalibela sites. For our primary investigation, the six basic…

Intelligent scheduling of the sequence of scientific exposures taken at ground-based astronomical observatories is massively challenging. Observing time is over-subscribed and atmospheric conditions are constantly changing. We propose to…

Ground-based photometry of bright stars is expected to be limited by atmospheric scintillation, although in practice observations are often limited by other sources of systematic noise. We analyse 122 nights of bright star ($G_{mag} <…

We present a study of the solar wind over different periods of the solar cycle, specifically focussing on the minimum between solar cycles 24 and 25, and the active, ascending phase of solar cycle 25. With the use of interplanetary…

We present first results of a simultaneous atmospheric turbulence measurement campaign at the Calar Alto (Spain) 1.23m and 3.5m telescopes. A SCIDAR instrument and the Calar Alto Adaptive Optics system ALFA were used at the 1.23m and 3.5m…

We present long-term density trends of the Earth's upper atmosphere at altitudes between 71 and 116 km, based on atmospheric occultations of the Crab Nebula observed with X-ray astronomy satellites, ASCA, RXTE, Suzaku, NuSTAR, and Hitomi.…