A water vapour monitor at Paranal Observatory

Kerber, F.; Rose, Thomas; Chacón, A.; Cuevas, Omar; Czekala, Harald; Hanuschik, R. W.; Momany, Y.; Navarrete, Julio; Querel, Richard; Smette, A.; Ancker, M. E. van den; Curé, M.; Naylor, David

doi:10.1117/12.924340

Cited by 24 publications

(19 citation statements)

References 5 publications

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“…The unit comprises the above humidity profiler (183-191 GHz), a temperature profiler (51-58 GHz), and an infrared radiometer (~10 μm) for cloud detection. Details of the instrument and its operations have been presented at a previous SPIE 13 .…”

Section: Support Of Science Operations: Pwvmentioning

confidence: 99%

VISIR upgrade overview and status

Kerber¹,

Käufl

Baksai

et al. 2014

SPIE Proceedings

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We present an overview of the VISIR upgrade project. VISIR is the mid-infrared imager and spectrograph at ESO's VLT. The project team is comprised of ESO staff and members of the original VISIR consortium: CEA Saclay and ASTRON. The project plan is based on input from the ESO user community with the goal of enhancing the scientific performance and efficiency of VISIR by a combination of measures: installation of improved hardware, optimization of instrument operations and software support. The cornerstone of the upgrade is the 1k by 1k Si:As AQUARIUS detector array (Raytheon) which has been carefully characterized in ESO's IR detector test facility (modified TIMMI 2 instrument). A prism spectroscopic mode will cover the N-band in a single observation. New scientific capabilities for high resolution and high-contrast imaging will be offered by sub-aperture mask (SAM) and phase-mask coronagraphic (4QPM/AGPM) modes. In order to make optimal use of favourable atmospheric conditions a water vapour monitor has been deployed on Paranal, allowing for real-time decisions and the introduction of a user-defined constraint on water vapour. During the commissioning in 2012 it was found that the on-sky sensitivity of the AQUARIUS detector was significantly below expectations and that VISIR was not ready to go back to science operations. Extensive testing of the detector arrays in the laboratory and on-sky enabled us to diagnose the cause for the shortcoming of the detector as excess low frequency noise (ELFN). It is inherent to the design chosen for this detector and can't be remedied by changing the detector set-up. Since this is a form of correlated noise its impact can be limited by modulating the scene recorded by the detector. We have studied several mitigation options and found that faster chopping using the secondary mirror (M2) of the VLT offers the most promising way forward. Faster M2 chopping has been tested and is scheduled for implementation before the end of 2014 after which we plan to re-commission VISIR. In addition an upgrade of the IT infrastructure related to VISIR is planned in order to support burst-mode operations. The upgraded VISIR will be a powerful instrument providing close to background limited performance for diffraction-limited observations at an 8-m telescope. It will offer synergy with facilities such as ALMA, JWST, VLTI and SOFIA, while a wealth of targets is available from survey work (e.g. VISTA, WISE). In addition it will bring confirmation of the technical readiness and scientific value of several aspects of potential mid-IR instrumentation at Extremely Large Telescopes.

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Section: Support Of Science Operations: Pwvmentioning

confidence: 99%

VISIR upgrade overview and status

Kerber¹,

Käufl

Baksai

et al. 2014

SPIE Proceedings

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“…For the SSO observatory we have access to high cadence zenith PWV measurements from the LHATPRO (Low Humidity And Temperature PROfiling radiometer) instrument at the Very Large Telescope in Cerro Paranal, situated approximately 150 m in altitude difference and 1.8 km in lateral distance from the SSO observatory. 68 To model the atmospheric conditions at the SSO observatory we use the Sky-Calc Sky Model Calculator, a tool developed by ESO which is based on the Cerro Paranal Advanced Sky Model. 69,70 This tool uses PWV and airmass values to provide a corresponding atmospheric transmission model.…”

Section: Photometric Quality and The Effect Of Precipitable Water Vapourmentioning

confidence: 99%

Development of the SPECULOOS exoplanet search project

Sebastian

Pedersen

Murray

et al. 2020

Ground-Based and Airborne Telescopes VIII

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SPECULOOS (Search for habitable Planets EClipsing ULtra-cOOl Stars) aims to perform a transit search on the nearest (< 40 pc) ultracool (< 3000K) dwarf stars. The project's main motivation is to discover potentially habitable planets well-suited for detailed atmospheric characterisation with upcoming giant telescopes, like the James Webb Space Telescope (JWST) and European Large Telescope (ELT). The project is based on a network of 1 m robotic telescopes, namely the four ones of the SPECULOOS-Southern Observatory (SSO) in Cerro Paranal, Chile, one telescope of the SPECULOOS-Northern Observatory (SNO) in Tenerife, and the SAINT-Ex telescope in San Pedro Mártir, Mexico. The prototype survey of the SPECULOOS project on the 60 cm TRAPPIST telescope (Chile) discovered the TRAPPIST-1 system, composed of seven temperate Earth-sized planets orbiting a nearby (12 pc) Jupiter-sized star. In this paper, we review the current status of SPECULOOS, its first results, the plans for its development, and its connection to the Transiting Exoplanet Survey Satellite (TESS) and JWST.

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“…Paranal is a very dry site with a median PWV of ~2.4 mm, offering excellent conditions for IR observations when real-time PWV information is taken into account. Its pronounced seasonal variations are welldocumented 1 . Similarly, the likelihood of clouds passing over Paranal is seasonally dependent.…”

Section: Introductionmentioning

confidence: 96%

“…Historical data are available through the ESO archive. The latest addition to this suite of instruments is a water vapour monitor in support of VLT science operations 1 . Atmospheric water vapour content can be expressed as precipitable water vapour (PWV) which is the equivalent condensed amount of water in an atmospheric column above the observer (as a depth in units of mm).…”

Section: Introductionmentioning

confidence: 99%

Quantifying photometric observing conditions on Paranal using an IR camera

Kerber¹,

Querel

Hanuschik³

2014

SPIE Proceedings

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A Low Humidity and Temperature Profiling (LHATPRO) microwave radiometer, manufactured by Radiometer Physics GmbH (RPG), is used to monitor sky conditions over ESO's Paranal observatory in support of VLT science operations. In addition to measuring precipitable water vapour (PWV) the instrument also contains an IR camera measuring sky brightness temperature at 10.5 µm. Due to its extended operating range down to -100 °C it is capable of detecting very cold and very thin, even sub-visual, cirrus clouds. We present a set of instrument flux calibration values as compared with a detrended fluctuation analysis (DFA) of the IR camera zenith-looking sky brightness data measured above Paranal taken over the past two years. We show that it is possible to quantify photometric observing conditions and that the method is highly sensitive to the presence of even very thin clouds but robust against variations of sky brightness caused by effects other than clouds such as variations of precipitable water vapour. Hence it can be used to determine photometric conditions for science operations. About 60 % of nights are free of clouds on Paranal. More work will be required to classify the clouds using this technique. For the future this approach might become part of VLT science operations for evaluating nightly sky conditions.

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A water vapour monitor at Paranal Observatory

Cited by 24 publications

References 5 publications

VISIR upgrade overview and status

VISIR upgrade overview and status

Development of the SPECULOOS exoplanet search project

Quantifying photometric observing conditions on Paranal using an IR camera

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