Atmospheric conditions at Cerro Armazones derived from astronomical data

Lakićević, M.; Kimeswenger, S.; Noll, Stefan; Kausch, W.; Unterguggenberger, Stefanie; Kerber, F.

doi:10.1051/0004-6361/201527973

Cited by 6 publications

(8 citation statements)

References 31 publications

(50 reference statements)

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“…Measurements of PWV such as those taken with L-HATPRO at Cerro Paranal (Section 2.3.1) are not available for Cerro Armazones. Nevertheless, estimates by Otárola et al (2010) and Lakićević et al (2016) suggest that the median value for clear sky conditions at Cerro Paranal, namely 2.47 mm (Section 2.3.2), should be relatively similar. Possible systematic deviations of the order of half a millimeter are not critical for our purposes.…”

Section: Ambient Meteorological Conditions At Cerro Armazonesmentioning

confidence: 95%

“…However, the latter and the dew point temperature calculated from it (Buck 1981) are only loosely correlated with the integrated water vapor column, that is, the scatter is large (Otárola et al 2010). Therefore, we have to use PWV (indicating the impact of the most important and highly variable trace gas H 2 O) to optimally parameterize the atmospheric radiation (Otárola et al 2010;Lakićević et al 2016).…”

Section: Individual Solutions and Local Estimatorsmentioning

confidence: 99%

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Bolometric night sky temperature and subcooling of telescope structures

Holzlöhner

Kimeswenger

Kausch

et al. 2020

A&A

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Context. The term sky temperature is used in the literature to refer to different phenomena in different contexts which often leads to confusion. In this work, we study T sky , the effective bolometric sky temperature at which a hemispherical black body would radiate the same power onto a flat horizontal structure on the ground as the night sky, integrated over the entire thermal wavelength range of 1-100 µm. We then analyze the thermal physics of radiative cooling with special focus on telescopes and discuss mitigation strategies. Aims. The quantity T sky is useful to quantify the subcooling in telescopes which can deteriorate the image quality by introducing an optical path difference (OPD) and induce thermal stress and mechanical deflections on structures. Methods. We employ the Cerro Paranal Sky Model of the European Southern Observatory to derive a simple formula of T sky as a function of atmospheric parameters. The structural subcooling and the induced OPD are then expressed as a function of surface emissivity, sky view factor, local air speed, and structure dimensions. Results. At Cerro Paranal (2 600 m) and Cerro Armazones (3 060 m) in the Atacama desert, T sky towards the zenith mostly lies 25-50 Kelvin below the ambient temperature near the ground, depending to a great extent on the precipitable water vapor (PWV) column in the atmosphere. The temperature difference can decrease by several Kelvin for higher zenith distances. The subcooling OPD scales linearly to quadratically with the telescope diameter and is inversely proportional to the local air speed near the telescope structure.

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Section: Ambient Meteorological Conditions At Cerro Armazonesmentioning

confidence: 95%

Section: Individual Solutions and Local Estimatorsmentioning

confidence: 99%

Bolometric night sky temperature and subcooling of telescope structures

Holzlöhner

Kimeswenger

Kausch

et al. 2020

A&A

View full text Add to dashboard Cite

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“…However, in the latitude range 19 o 30' S to 25 o S, there is no significant discontinuity in the coastal mountain range (Grenon M., 1990). Certainly, there are factors that contribute to seasonal and annual variability, but in the overall the area is well known for its extreme dryness (Garreaud, R., 2011, Turner et al, 2012, Lakićević et al, 2016, enabling a large fraction of usable nights for up to 89% of the nights in the year (Otarola & Hickson, 2017).…”

Section: Sites: Selected Sites Of Great Potential For Astronomy Projementioning

confidence: 99%

Precipitable Water Vapor, Temperature, and Wind Statistics At Sites Suitable for mm and Submm Wavelength Astronomy in Northern Chile

Otárola

Breuck

Travouillon

et al. 2019

PASP

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Atmospheric water vapor is the main limiting factor of atmospheric transparency in the mm and submm wavelength spectral windows. Thus, dry sites are needed for the installation and successful operation of radio astronomy observatories exploiting those spectral windows. Temperature and wind are variables of special consideration when planning the installation and operation of large-aperture radio telescopes, as these parameters affect the mechanical response of radio telescopes exposed to the environmental conditions. Temperature, and in particular temperature gradients, induce thermal deformation of mechanical structures, while high wind speeds and gusts induce pointing jitter affecting the tracking accuracy of astronomical sources during the observations. This work summarizes the statistics of precipitable water vapor (PWV), temperature, and wind monitored at sites by the coastal mountain range, as well as on the west slope of the Andes mountain range in the region of Antofagasta, Chile. This information could prove useful for the planning of extended baselines for the Atacama Large Millimeter and Accepted for publication under Open Access terms at the Publications of the Astronomical Society of the Pacific (PASP) JournalSubmillimeter Array (ALMA), and/or new radio telescope projects, such as the Atacama Large Aperture Submm/ mm Telescope (AtLAST) initiative. 6 https://sitedata.tmt.org/ 7

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“…On the other hand, Molecfit has been used to search for water vapour on exoplanet atmospheres (Allart et al 2017) and to study the atmospheric conditions above ESO's new astronomical site Cerro Amazones (Lakićević et al 2016). The quest for Earth-like planets around M dwarf drives the development of infrared high-resolution spectrographs.…”

Section: Introductionmentioning

confidence: 99%

Telluric correction in the near-infrared: Standard star or synthetic transmission?

Ulmer-Moll

Figueira

Neal

et al. 2019

A&A

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Context. The atmospheric absorption of the Earth is an important limiting factor for ground-based spectroscopic observations and the near-infrared and infrared regions are the most affected. Several software packages that produce a synthetic atmospheric transmission spectrum have been developed to correct for the telluric absorption; these are Molecfit, TelFit, and Transmissions Atmosphériques Personnalisées pour l'AStronomie (TAPAS). Aims. Our goal is to compare the correction achieved using these three telluric correction packages and the division by a telluric standard star. We want to evaluate the best method to correct near-infrared high-resolution spectra as well as the limitations of each software package and methodology. Methods. We applied the telluric correction methods to CRIRES archival data taken in the J and K bands. We explored how the achieved correction level varies depending on the atmospheric T-P profile used in the modelling, the depth of the atmospheric lines, and the molecules creating the absorption. Results. We found that the Molecfit and TelFit corrections lead to smaller residuals for the water lines. The standard star method corrects best the oxygen lines. The Molecfit package and the standard star method corrections result in global offsets always below 0.5% for all lines; the offset is similar with TelFit and TAPAS for the H 2 O lines and around 1% for the O 2 lines. All methods and software packages result in a scatter between 3% and 7% inside the telluric lines. The use of a tailored atmospheric profile for the observatory leads to a scatter two times smaller, and the correction level improves with lower values of precipitable water vapour. Conclusions. The synthetic transmission methods lead to an improved correction compared to the standard star method for the water lines in the J band with no loss of telescope time, but the oxygen lines were better corrected by the standard star method.

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Atmospheric conditions at Cerro Armazones derived from astronomical data

Cited by 6 publications

References 31 publications

Bolometric night sky temperature and subcooling of telescope structures

Bolometric night sky temperature and subcooling of telescope structures

Precipitable Water Vapor, Temperature, and Wind Statistics At Sites Suitable for mm and Submm Wavelength Astronomy in Northern Chile

Telluric correction in the near-infrared: Standard star or synthetic transmission?

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