The night sky conditions at the Sacramento Peak Observatory. II - Cloud cover, seeing, and precipitable water

Beckers, J. M.; Breedlove, W. O.; Devegvar, P. G. N.; Johansen, E. E.; Gilliam, L. B.; Mann, G.; Mauter, H. A.; Phillis, G. L.; Demastus, H. L.

doi:10.1086/130600

Cited by 8 publications

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“…The spectrograms centered at 0.55 jam were traced with the PDS microdensitometer at the University of Hawaii and reduced to relative intensity units using appropriate calibration data. A line identification study was undertaken by comparison with the Sacramento Peak Observatory solar flux atlas (Beckers, Bridges, and Gilliam 1976) and with lunar spectra observed and reduced with the same equipment and techniques as those applied to HD 15144. This study revealed the excessive strength of Cr n, and to a lesser extent, Fe n and i, which are characteristic of the blue spectrum.…”

Section: B a Search For The Spectrum Of The Companionmentioning

confidence: 99%

HD 15144, a magnetic AP star with a possible intrinsic periodic variation of the magnetic field

Bonsack

1981

PASP

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HD 15144 (HR 710) is a single-line spectroscopic binary Ap star with a period of 3^00, which has a variable magnetic field but no obvious variations in line strengths or light. New spectrograms are combined with previous observations by Babcock to derive a probable magnetic period of 15?9. An apparent rotational velocity of 7.7 km s -1 is obtained and combined with elements of the orbit to estimate the mass of the secondary. The spectrum of the secondary cannot be detected between 3800 Â and 6700 Â. The most plausible model for the system appears to be one in which the rotation period of the Ap star is 3?00, the system is seen nearly pole-on, the secondary is a subluminous star of approximately 1.2 solar masses, and the magnetic variation is due to intrinsic changes of the field strength or geometry. An alternative model assumes that the rotation period of the Ap star is 15?9 days, the system is seen edge-on, the mass of the secondary is 0.2 solar mass, and the magnetic variation is due to rotation with a fixed, but very asymmetric, magnetic field geometry.

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Section: B a Search For The Spectrum Of The Companionmentioning

confidence: 99%

HD 15144, a magnetic AP star with a possible intrinsic periodic variation of the magnetic field

Bonsack

1981

PASP

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“…Based on direct measurements of the thermal structure parameter C x 2 , the contribution of thé lower ground layer to the total seeing was found to be negligible at night. Beckers et al (1979) have reported seeing measurements from the similar forested summit of Sacramento Peak, which is not too far from Mount Graham but somewhat lower in altitude. They also found very good nighttime seeing conditions which were slightly worse than those reported here.…”

Section: Introductionmentioning

confidence: 99%

Seeing measurements on Mount Graham

Ulich¹,

Davison²

1985

PASP

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A transportable 30-cm aperture telescope was constructed and used with a CCD camera to measure stellar image motion as seen from the summit of Mount Graham in southeastern Arizona. Based on observations during eight nights in October and November 1984, the average value of Fried's length r 0 (Fried 1967) at 0.5 |xm wavelength is 13 cm at the zenith, implying a long-exposure visual image full width at half maximum of 0.8 arc second. Since only a small number of nights have been tested, the statistical uncertainty in the average seeing conditions is large and these results should be regarded as preliminary. No large differences were found among three different sites or between different heights of the telescope above the ground. Direct measurements of thermal turbulence in the first few tens of meters above ground indicate that telescopes may be located within a few meters of the ground and well below treetop height without significant seeing degradation.

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“…Alternatively, the Sun can be made to appear point-like by observing its image formed by a distant convex mirror (Edmonds 1975;private communication). In one case a very shortfocal-length lens was used to get a tiny solar image in its entirety into a spectrograph slit (Beckers et al 1976). In another case fiber optics served a similar purpose (Gray 1972).…”

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confidence: 99%

The inferred color index of the sun

Gray

1992

PASP

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The night sky conditions at the Sacramento Peak Observatory. II - Cloud cover, seeing, and precipitable water

Abstract: A summary is given of the following atmospheric conditions at the Sacramento Peak Observatory: cloud cover, seeing, and précipitable water. Sky brightness observations have been reported in an earlier paper.

Cited by 8 publications

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HD 15144, a magnetic AP star with a possible intrinsic periodic variation of the magnetic field

HD 15144, a magnetic AP star with a possible intrinsic periodic variation of the magnetic field

Seeing measurements on Mount Graham

The inferred color index of the sun

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