We present a statistical analysis of r0 and θ0 measurements
collected over the last 2 decades at 18 different sites. Although the site
altitudes varied from sea level to 3 km, the major distinguishing feature
between average r0 values was the
presence or absence of a turbulent, atmospheric boundary layer above the
surface. For locations without a strong boundary-layer inversion, the mean
coherence length, r0, was 93
± 6 mm and the mean isoplanatic angle, θ0,
was 9.4 ± 0.5 µrad. Where a boundary-layer inversion was present,
the corresponding values for r0
and θ0 were 53 ± 2 mm and 6.5 ± 0.5
µrad, respectively.
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Measured values are for vertical paths at
a reference wavelength of 500 nm.
Values are the antilog of the
mean of the logarithm of the data.
This a multiplicative factor
corresponding to the antilog of one standard deviation of the log of the data.
Limited duration data sets that
did not cover a variety of atmospheric conditions.
The Haleakala
r0 data used a rotating reticle
seeing monitor built by Hughes Aircraft Company mounted on a 1.2-m telescope
at the U.S. Air Force Maui Observatory Station and covered the period
1984–1990. The data include a 3× diffraction-limited optical beam
quality correction factor for the 1.2 m telescope and a 2× diffraction
beam quality factor for optics of the seeing monitor. Data were collected by
R. Duel and processed and provided by J. Oldenettel.
Sites with known, strong,
elevated boundary-layer inversions >50 m above the surface.
Early White Sands Missile
Range, New Mexico (1977–1978), and Lone Butte, China Lake, California
(1979), r0 data sets computed the
MTF from the Fourier transform of digitized, photographic star trails.
Data collected at the Starfire
Optical Range, Albuquerque, New Mexico, by U.S. Air Force personnel with
instrumentation developed and supplied by the author. Data were provided by R.
Fugate and A. Slavin.
Table 2
Site Names, Locations, Altitudes, Relative Relief of
Site Above the Prevailing Terrain, Topography, and Telescope Dome
Diameters
Altitude Relief
Site
Location
(m)
(m)
Topography
Dome (m)
Anderson Mesa
East of Flagstaff, Az.
2200
200
E-W mesa
na
Anderson Peak
Big Sur, Calif.
1250
1000
N-S coastal ridge
na
Chileo Flats
7.5 km north of Mt. Wilson
1550
300
Low ridge
na
Mt. Haleakala
Mt. Haleakaka, Maui, Hi.
3040
3000
Island Volcano
20
Kihei
1 km east Kihei Research Park, Maui Hi.
100
2
Alluvial fan
na
Mt. Laguna
140 km east San Diego, Calif.
1940
400
N-S coastal mountain
na
Lick Observatory
0.6-m telescope, Mt. Hamilton, Calif.
1300
500
E-W ridge
8
Lone Butte
China Lake, Calif.
900
240
Isolated hill
3
Malabar
1 km west Melborne, Fla.
50
2
Flat everglade
na
McDonald Observatory
3.2-m telescope, Mt. Locke, Tex.
2000
300
Low mountain
20
Mohave Desert
Mohave Desert, Calif.
1000
230
Low mountain
3
Starfire Optical Range
Southeast of Albuquerque, N.M.
1700
70
Isolated low hill
2
White Sands: Desert
Tularosa Basin, White Sands, N.M.
1380
8
Flat arid desert
3
White Sands: North Site
10 km north Trinity Site, N.M.
1380
70
Small hill
3
White Sands: North Oscura Peak
Sierra Oscura Range, N.M.
2600
900
N-S escarpment
3
White Sands: Quartzite Mountain
Johnson Space Center, White Sands N.M.
1830
450
N-S rounded fault block
3
Vieques
Naval Facility, Vieques, P.R.
20
2
Alluvial fan
na
Mt. Wilson
0.6-m telescope, Mt. Wilson, Calif.
1800
1500
E-W escarpment
4
Tables (2)
Table 1
Logarithmic Means and Standard Deviations of Nocturnal
Atmospheric Coherence Lengths and Isoplanatic Anglesa
Measured values are for vertical paths at
a reference wavelength of 500 nm.
Values are the antilog of the
mean of the logarithm of the data.
This a multiplicative factor
corresponding to the antilog of one standard deviation of the log of the data.
Limited duration data sets that
did not cover a variety of atmospheric conditions.
The Haleakala
r0 data used a rotating reticle
seeing monitor built by Hughes Aircraft Company mounted on a 1.2-m telescope
at the U.S. Air Force Maui Observatory Station and covered the period
1984–1990. The data include a 3× diffraction-limited optical beam
quality correction factor for the 1.2 m telescope and a 2× diffraction
beam quality factor for optics of the seeing monitor. Data were collected by
R. Duel and processed and provided by J. Oldenettel.
Sites with known, strong,
elevated boundary-layer inversions >50 m above the surface.
Early White Sands Missile
Range, New Mexico (1977–1978), and Lone Butte, China Lake, California
(1979), r0 data sets computed the
MTF from the Fourier transform of digitized, photographic star trails.
Data collected at the Starfire
Optical Range, Albuquerque, New Mexico, by U.S. Air Force personnel with
instrumentation developed and supplied by the author. Data were provided by R.
Fugate and A. Slavin.
Table 2
Site Names, Locations, Altitudes, Relative Relief of
Site Above the Prevailing Terrain, Topography, and Telescope Dome
Diameters
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