Atmospheric and facility seeing on Mauna Kea, Hawaii

Racine, R.

doi:10.1086/132453

Cited by 4 publications

(1 citation statement)

References 7 publications

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“…In their analysis of the performances of SpeX during its first years of operation, Rayner et al (2004) noted that observing away from the parallactic angle can induce a slope variation of about 7% across the 2.5 μm baseline. However, the authors used a narrower slit of 0 3, against 0 8 in our case (i.e., larger than the average seeing of ∼0 5 at Maunakea; e.g., Racine 1989 and the Appendix). We therefore stress that our conclusions are only valid in the case of observations conducted with the wider 0 8 slit, the most commonly used slit in spectroscopic surveys of asteroids.…”

Section: Systematic Errorsmentioning

confidence: 96%

Twenty Years of SpeX: Accuracy Limits of Spectral Slope Measurements in Asteroid Spectroscopy

Marsset¹,

DeMeo²,

Binzel³

et al. 2020

ApJS

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We examined two decades of SpeX/NASA Infrared Telescope Facility observations from the Small Main-Belt Asteroid Spectroscopic Survey (SMASS) and the MIT-Hawaii Near-Earth Object Spectroscopic Survey (MITHNEOS) to investigate uncertainties and systematic errors in reflectance spectral slope measurements of asteroids. From 628 spectra of 11 solar analogs used for calibration of the asteroid spectra, we derived an uncertainty of s m = ¢ -4.2% m s 1 on slope measurements over 0.8-2.4 μm. Air mass contributes to −0.92% μm −1 per 0.1 unit air mass difference between the asteroid and the solar analog and therefore for an overall 2.8% μm −1 slope variability in SMASS and MITHNEOS designed to operate within 1.0-1.3 air mass. No additional observing conditions (including the parallactic angle, seeing, and humidity) were found to contribute systematically to slope change. We discuss implications for asteroid taxonomic classification works. Uncertainties provided in this study should be accounted for in future compositional investigation of small bodies to distinguish intrinsic heterogeneities from possible instrumental effects.Unified Astronomy Thesaurus concepts: Spectroscopy (1558); Main belt asteroids (2036); Near-Earth objects (1092); Small solar system bodies (1469); Astronomical instrumentation (799)

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Section: Systematic Errorsmentioning

confidence: 96%

Twenty Years of SpeX: Accuracy Limits of Spectral Slope Measurements in Asteroid Spectroscopy

Marsset¹,

DeMeo²,

Binzel³

et al. 2020

ApJS

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Hokupa`a Anisoplanatism and Mauna Kea Turbulence Characterization

Flicker¹,

Rigaut

2002

PUBL ASTRON SOC PAC

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A data set of adaptive optics images has been analyzed in order to study the effects of angular anisoplanatism and to characterize Mauna Kea nighttime turbulence. The data set consists of a selection of Galactic center images obtained with the adaptive optics instrument Hokupa'a and the near-infrared camera QUIRC on the Gemini-North 8 m telescope. Using the Strehl ratio and the FWHM as tracers for anisoplanatism in the images, it is possible to draw conclusions about the effective turbulence height by model-fitting synthetic h data. From the relatively small statistical sample, we obtain a median km, with 10th and 90th percentiles h p 3.5 being 2.2 and 5.6 km. The implications of these findings for a turbulence-conjugated adaptive optics system are addressed. We also find the Zernike modal equivalent of Hokupa'a to be , i.e., on the average slightly N ≈ 18 better than 4 radial degrees.

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The Night Sky at the Calar Alto Observatory

Sánchez¹,

Aceituno²,

Thiele³

et al. 2007

PUBL ASTRON SOC PAC

106

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We present a characterization of the main properties of the night-sky at the Calar Alto observatory for the time period between 2004 and 2007. We use optical spectrophotometric data, photometric calibrated images taken in moonless observing periods, together with the observing conditions regularly monitored at the observatory, such as atmospheric extinction and seeing. We derive, for the first time, the typical moonless night-sky optical spectrum for the observatory. The spectrum shows a strong contamination by different pollution lines, in particular from Mercury lines, which contribution to the sky-brightness in the different bands is of the order of ∼0.09 mag, ∼0.16 mag and ∼0.10 mag in B, V and R respectively. Regarding the strength of the Sodium pollution line in comparison with the airglow emission, the observatory does not fulfill the IAU recomendations of a dark site. The zenith-corrected values of the moonless night-sky surface brightness are 22. 39, 22.86, 22.01, 21.36 and 19.25 mag arcsec −2 in U , B, V , R and I, which indicates that Calar Alto is a particularly dark site for optical observations up to the I-band. The fraction of astronomical useful nights at the observatory is ∼70%, with a ∼30% of photometric nights. The typical extinction at the observatory is κ V ∼0.15 mag in the Winter season, with little dispersion. In summer the extinction has a wider range of values, although it does not reach the extreme peaks observed at other sites. The analysis of the Winter and summer extinction curves indicates that the Rayleigh scattering is almost constant along the year. The rise of the extinction in the summer season is due to an enhance of the Aerosol extinction, most probably associated with an increase of dust in the atmosphere. The median seeing for the last two years (2005-6) was ∼0.90 ′′ , being smaller in the Summer (∼0.87 ′′ ) than in the Winter (∼0.96 ′′ ). We conclude in general that after 26 years of operations Calar Alto is still a good astronomical site. Its main properties are similar in many aspects to those of other major observatories where 10m-like telescopes are under operation or construction, being a natural candidate for future large aperture optical telescopes.

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Atmospheric and facility seeing on Mauna Kea, Hawaii

Cited by 4 publications

References 7 publications

Twenty Years of SpeX: Accuracy Limits of Spectral Slope Measurements in Asteroid Spectroscopy

Twenty Years of SpeX: Accuracy Limits of Spectral Slope Measurements in Asteroid Spectroscopy

Hokupa`a Anisoplanatism and Mauna Kea Turbulence Characterization

The Night Sky at the Calar Alto Observatory

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