&lt;title&gt;Survey of airborne particle density and the aging of mirror coatings in the open air at the VLT Observatory&lt;/title&gt;

Giordano, P.; Sarazin, M.

doi:10.1117/12.176156

Cited by 6 publications

(9 citation statements)

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“…1 The third "season" starts at the beginning of October and goes through the end of the year, and it continues to have low dust levels with greater variability than in the second season. 1 Similar seasons were noticed at Cerro Paranal, 3 Chile, except that during their fall and winter the dust levels of large particles were much lower than even in the lowest dust level "season" at the APO.…”

Section: Seasonal Variationssupporting

confidence: 66%

“…3 After 200 days, there was a measurable increase in roughness and decrease in reflectiviy of all the mirrors, as would be expected. For instance, one mirror increased surface roughness from 10Å originally to 137.7Å and decreased reflectivity from 90.1% to 76.4% (at 670 nm) (see paper for details).…”

Section: Cerro Paranalmentioning

confidence: 60%

“…3 Primary mirrors were found to be more effected by dust than secondary mirrors. This was concluded to be a result of the different ways that primary and secondary mirrors face -upward facing mirrors have more dust settle on them.…”

Section: Cerro Paranalmentioning

confidence: 97%

“…The experiment showed that the primary mirrors had lost about 6.5% of their reflectivity (at 650 nm) and the secondary mirror had only lost about 3%. 3 After applying a peel-off product, which had resulted in 100% effectiveness when applied to mirrors that were exposed in laboratory, the primary mirror recovered about 3.5% of the lost reflectivity and the secondary mirror recovered only about 1%. 3 This suggests that permanent damage was done to the mirrors which could be blamed on particles hitting the mirrors under strong winds.…”

Section: How Much Exposure Is Recoverable By Cleaning?mentioning

confidence: 99%

“…3 Four mirrors were exposed to dust and had lateral protection from wind over a period of more than a year. The experiment showed that the primary mirrors had lost about 6.5% of their reflectivity (at 650 nm) and the secondary mirror had only lost about 3%.…”

Section: How Much Exposure Is Recoverable By Cleaning?mentioning

confidence: 99%

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Effects of airborne particles on optical equipment

Gorgievska

Steinebach

2004

New Frontiers in Stellar Interferometry

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Observatories are affected by dust particles in the air and those that settle on the mirror surfaces. Here we analyze seven years of weather and dust particle data from the Apache Point Observatory (APO) in Sunspot, New Mexico, to find correlations between dust and other weather factors, and also find correlations between the APO data and the Magdalena Ridge Observatory(MRO) weather data. Exposure of optics to strong dust events should be avoided, so we considered different possible observatory closure criteria based on these data.

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Section: Seasonal Variationssupporting

confidence: 66%

Section: Cerro Paranalmentioning

confidence: 60%

Section: Cerro Paranalmentioning

confidence: 97%

Section: How Much Exposure Is Recoverable By Cleaning?mentioning

confidence: 99%

Section: How Much Exposure Is Recoverable By Cleaning?mentioning

confidence: 99%

See 3 more Smart Citations

Effects of airborne particles on optical equipment

Gorgievska

Steinebach

2004

New Frontiers in Stellar Interferometry

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Astronomical site survey report on dust measurement, wind profile, optical turbulence, and their correlation with seeing over IAO-Hanle

et al. 2017

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Raman-scattered laser guide-star photons to monitor the scatter of astronomical telescope mirrors

Vogt

Álvarez

Calia

et al. 2018

A&A

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The first observations of laser guide star photons Raman-scattered by air molecules above the Very Large Telescope (VLT) were reported in June 2017. The initial detection came from the Multi-Unit Spectroscopic Explorer (MUSE) optical integral field spectrograph, following the installation of the 4 Laser Guide Star Facility (4LGSF) on the Unit Telescope 4 (UT4) of the VLT. In this Letter, we delve further into the symbiotic relationship between the 4LGSF laser guide star system, the UT4 telescope, and MUSE by monitoring the spectral contamination of MUSE observations by Raman photons over a 27 month period. This dataset reveals that dust particles deposited on the primary and tertiary mirrors of UT4 -responsible for a reflectivity loss of ∼8% at 6000 Å -contribute (60 ± 5)% to the laser line fluxes detected by MUSE. The flux of Raman lines, contaminating scientific observations acquired with optical spectrographs, thus provides a new, non-invasive means to monitor the evolving scatter properties of the mirrors of astronomical telescopes equipped with laser guide star systems.A&A proofs: manuscript no. Vogt2018_Raman of the series of experiments presented by Vogt et al. (2017). In the remainder of this Letter, all wavelengths are quoted in air, unless explicitly mentioned otherwise. Whenever we refer to laser photons, we mean photons that were originally emitted by the laser guide star system, irrespective of whether they were subsequently Rayleigh-scattered, Mie-scattered, Raman-scattered, or absorbed and re-emitted by a sodium atom.

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<title>Survey of airborne particle density and the aging of mirror coatings in the open air at the VLT Observatory</title>

Cited by 6 publications

References 0 publications

Effects of airborne particles on optical equipment

Effects of airborne particles on optical equipment

Astronomical site survey report on dust measurement, wind profile, optical turbulence, and their correlation with seeing over IAO-Hanle

Raman-scattered laser guide-star photons to monitor the scatter of astronomical telescope mirrors

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