Study on the precision of the multiaperture scintillation sensor turbulence profiler (MASS) employed in the site testing campaign for the Thirty Meter Telescope
S. G. Els, M. Schöck, J. Seguel, A. Tokovinin, V. Kornilov, R. Riddle, W. Skidmore, T. Travouillon, K. Vogiatzis, R. Blum, E. Bustos, B. Gregory, J. Vasquez, D. Walker, and P. Gillett
S. G. Els,1,2,*
M. Schöck,2
J. Seguel,1
A. Tokovinin,1
V. Kornilov,3
R. Riddle,2
W. Skidmore,2
T. Travouillon,2
K. Vogiatzis,2
R. Blum,4
E. Bustos,1
B. Gregory,1
J. Vasquez,1
D. Walker,1
and P. Gillett2
1Cerro Tololo Inter-American Observatory, Casilla 603, La Serena, Chile
2Thirty Meter Telescope Project, 2632 E. Washington Boulevard, Pasadena, California 91107, USA
3Sternberg Astronomical Institute, Universitetsky prospekt 13, 119992 Moscow, Russia
4National Optical Astronomy Observatory, 950 N. Cherry Avenue, Tucson, Arizona 85719, USA
S. G. Els, M. Schöck, J. Seguel, A. Tokovinin, V. Kornilov, R. Riddle, W. Skidmore, T. Travouillon, K. Vogiatzis, R. Blum, E. Bustos, B. Gregory, J. Vasquez, D. Walker, and P. Gillett, "Study on the precision of the multiaperture scintillation sensor turbulence profiler (MASS) employed in the site testing campaign for the Thirty Meter Telescope," Appl. Opt. 47, 2610-2618 (2008)
The multiaperture scintillation sensor (MASS) has become a device widely employed to measure the altitude distribution of atmospheric turbulence. An empirical study is reported that investigates the dependence of the MASS results on the knowledge of the instrumental parameters. Also, the results of a side-by-side comparison of two MASS instruments are presented, indicating that MASS instruments permit measurements of the integrated seeing to a precision better than and of the individual turbulence layer strength to better than .
Lianqi Wang, Matthias Schöck, Gary Chanan, Warren Skidmore, Robert Blum, Edison Bustos, Sebastian Els, Reed Riddle, Juan Seguel, Tony Travouillon, Joselino Vasquez, David Walker, and Paul Gillett Appl. Opt. 46(25) 6460-6468 (2007)
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Summary of the Sensitivity Study of the Dependence of MASS Seeing on Instrumental Parametersa
Case
Mag
ΔMedian (arc sec)
ΔMean (arc sec)
Slope
rms (arc sec)
1a
12
1.0
1.0
1.0
1.0
12.0
12.0
12.0
12.0
0.06
0.07
0.905
0.04
1b
13
1.0
1.0
1.0
1.0
12.0
12.0
12.0
12.0
0.03
0.03
0.950
0.02
1c
14
1.0
1.0
1.0
1.0
12.0
12.0
12.0
12.0
0.00
0.00
1.00
0.00
1d
15
1.0
1.0
1.0
1.0
12.0
12.0
12.0
12.0
0.03
1.057
0.02
1e
16
1.0
1.0
1.0
1.0
12.0
12.0
12.0
12.0
0.03
1.117
0.02
2a
14
1.025
1.0
1.0
1.0
12.0
12.0
12.0
12.0
−0.01
0.992
0.01
2b
14
1.050
1.0
1.0
1.0
12.0
12.0
12.0
12.0
0.988
0.02
2c
14
1.075
1.0
1.0
1.0
12.0
12.0
12.0
12.0
0.987
0.02
2d
14
1.100
1.0
1.0
1.0
12.0
12.0
12.0
12.0
0.991
0.02
3a
14
1.0
1.025
1.0
1.0
12.0
12.0
12.0
12.0
0.998
0.01
3b
14
1.0
1.050
1.0
1.0
12.0
12.0
12.0
12.0
0.995
0.01
3c
14
1.0
1.075
1.0
1.0
12.0
12.0
12.0
12.0
0.992
0.01
3d
14
1.0
1.100
1.0
1.0
12.0
12.0
12.0
12.0
0.989
0.01
4a
14
1.0
1.0
1.025
1.0
12.0
12.0
12.0
12.0
0.999
0.01
4b
14
1.0
1.0
1.050
1.0
12.0
12.0
12.0
12.0
0.998
0.01
4c
14
1.0
1.0
1.075
1.0
12.0
12.0
12.0
12.0
0.998
0.01
4d
14
1.0
1.0
1.100
1.0
12.0
12.0
12.0
12.0
0.998
0.01
5a
14
1.0
1.0
1.0
1.025
12.0
12.0
12.0
12.0
1.001
0.01
5b
14
1.0
1.0
1.0
1.050
12.0
12.0
12.0
12.0
1.001
0.01
5c
14
1.0
1.0
1.0
1.075
12.0
12.0
12.0
12.0
1.000
0.01
5d
14
1.0
1.0
1.0
1.100
12.0
12.0
12.0
12.0
1.000
0.01
6a
14
1.0
1.0
1.0
1.0
10.0
12.0
12.0
12.0
1.000
0.01
6b
14
1.0
1.0
1.0
1.0
11.0
12.0
12.0
12.0
1.000
6c
14
1.0
1.0
1.0
1.0
13.0
12.0
12.0
12.0
1.000
6d
14
1.0
1.0
1.0
1.0
14.0
12.0
12.0
12.0
1.000
7a
14
1.0
1.0
1.0
1.0
12.0
10.0
12.0
12.0
1.000
0.01
7b
14
1.0
1.0
1.0
1.0
12.0
11.0
12.0
12.0
1.000
7c
14
1.0
1.0
1.0
1.0
12.0
13.0
12.0
12.0
1.001
7d
14
1.0
1.0
1.0
1.0
12.0
14.0
12.0
12.0
1.001
8a
14
1.0
1.0
1.0
1.0
12.0
12.0
10.0
12.0
1.000
0.01
8b
14
1.0
1.0
1.0
1.0
12.0
12.0
11.0
12.0
1.000
0.01
8c
14
1.0
1.0
1.0
1.0
12.0
12.0
13.0
12.0
1.000
0.01
8d
14
1.0
1.0
1.0
1.0
12.0
12.0
14.0
12.0
1.000
0.01
9a
14
1.0
1.0
1.0
1.0
12.0
12.0
12.0
10.0
1.001
0.01
9b
14
1.0
1.0
1.0
1.0
12.0
12.0
12.0
11.0
1.001
0.01
9c
14
1.0
1.0
1.0
1.0
12.0
12.0
12.0
13.0
1.001
0.01
9d
14
1.0
1.0
1.0
1.0
12.0
12.0
12.0
14.0
1.000
0.01
More than 11,000 individual MASS observations taken at Cerro Armazones during April 2006 by the TMT T2 site testing system were used for this study. “Mag” indicates the instrument magnification. P and are the Poisson and nonlinearity parameters of the subaperture PMT. All cases were compared with the results obtained in case 1c. Δ median indicates the difference between the median of a case seeing and the median of the reference case seeing. Δ mean indicates the corresponding difference between the mean seeing of these cases. The slope was obtained by a linear fit to the seeing data, e.g., case 1a versus case 1c.
Table 2
Summary of the Sensitivity Study of the Dependence of MASS Seeing and Isoplanatic Angle on Spectral Responsea
Telescope
MASS unit
Spectral Response
ΔMedian Seeing (arc sec)
ΔMean Seeing (arc sec)
rms Seeing (arc sec)
ΔMedian (arc sec)
ΔMean (arc sec)
rms (arc sec)
T2
MD 6
without.crv
0.10
0.02
0.67
T4
MD 10
without.crv
0.07
0.21
eso_md.crv
0.08
0.08
0.06
0.16
T6
MD 8
without.crv
0.14
1.43
All numbers were obtained by comparison with the results based on the spectral response function mass.crv. To obtain these results, data taken between July and September 2006 were used, resulting in more than 7200, 10,100 and 12,100 individual data records for T2, T4, and T6, respectively.
Table 3
Main Results from the Side-by-Side Comparison of Two TMT Site Survey Instruments, T2 and T3, on Cerro Tololoa
MASS Result
Seeing (arc sec)
0.073
0.001
0.003
0.096
0.020
0.032
0.166
The results were obtained only from data for which .
Table 4
Site-by-Site Comparison Results for Data Taken between 5 and 14 September 2007a
MASS result
Seeing (arc sec)
0.05
0.04
0.11
0.07
0.02
0.06
0.10
As in Table 3, 1826 data records, for which T2 showed some vignetting. These are compared with the simultaneously obtained data taken with T3, which was not vignetted.
Tables (4)
Table 1
Summary of the Sensitivity Study of the Dependence of MASS Seeing on Instrumental Parametersa
Case
Mag
ΔMedian (arc sec)
ΔMean (arc sec)
Slope
rms (arc sec)
1a
12
1.0
1.0
1.0
1.0
12.0
12.0
12.0
12.0
0.06
0.07
0.905
0.04
1b
13
1.0
1.0
1.0
1.0
12.0
12.0
12.0
12.0
0.03
0.03
0.950
0.02
1c
14
1.0
1.0
1.0
1.0
12.0
12.0
12.0
12.0
0.00
0.00
1.00
0.00
1d
15
1.0
1.0
1.0
1.0
12.0
12.0
12.0
12.0
0.03
1.057
0.02
1e
16
1.0
1.0
1.0
1.0
12.0
12.0
12.0
12.0
0.03
1.117
0.02
2a
14
1.025
1.0
1.0
1.0
12.0
12.0
12.0
12.0
−0.01
0.992
0.01
2b
14
1.050
1.0
1.0
1.0
12.0
12.0
12.0
12.0
0.988
0.02
2c
14
1.075
1.0
1.0
1.0
12.0
12.0
12.0
12.0
0.987
0.02
2d
14
1.100
1.0
1.0
1.0
12.0
12.0
12.0
12.0
0.991
0.02
3a
14
1.0
1.025
1.0
1.0
12.0
12.0
12.0
12.0
0.998
0.01
3b
14
1.0
1.050
1.0
1.0
12.0
12.0
12.0
12.0
0.995
0.01
3c
14
1.0
1.075
1.0
1.0
12.0
12.0
12.0
12.0
0.992
0.01
3d
14
1.0
1.100
1.0
1.0
12.0
12.0
12.0
12.0
0.989
0.01
4a
14
1.0
1.0
1.025
1.0
12.0
12.0
12.0
12.0
0.999
0.01
4b
14
1.0
1.0
1.050
1.0
12.0
12.0
12.0
12.0
0.998
0.01
4c
14
1.0
1.0
1.075
1.0
12.0
12.0
12.0
12.0
0.998
0.01
4d
14
1.0
1.0
1.100
1.0
12.0
12.0
12.0
12.0
0.998
0.01
5a
14
1.0
1.0
1.0
1.025
12.0
12.0
12.0
12.0
1.001
0.01
5b
14
1.0
1.0
1.0
1.050
12.0
12.0
12.0
12.0
1.001
0.01
5c
14
1.0
1.0
1.0
1.075
12.0
12.0
12.0
12.0
1.000
0.01
5d
14
1.0
1.0
1.0
1.100
12.0
12.0
12.0
12.0
1.000
0.01
6a
14
1.0
1.0
1.0
1.0
10.0
12.0
12.0
12.0
1.000
0.01
6b
14
1.0
1.0
1.0
1.0
11.0
12.0
12.0
12.0
1.000
6c
14
1.0
1.0
1.0
1.0
13.0
12.0
12.0
12.0
1.000
6d
14
1.0
1.0
1.0
1.0
14.0
12.0
12.0
12.0
1.000
7a
14
1.0
1.0
1.0
1.0
12.0
10.0
12.0
12.0
1.000
0.01
7b
14
1.0
1.0
1.0
1.0
12.0
11.0
12.0
12.0
1.000
7c
14
1.0
1.0
1.0
1.0
12.0
13.0
12.0
12.0
1.001
7d
14
1.0
1.0
1.0
1.0
12.0
14.0
12.0
12.0
1.001
8a
14
1.0
1.0
1.0
1.0
12.0
12.0
10.0
12.0
1.000
0.01
8b
14
1.0
1.0
1.0
1.0
12.0
12.0
11.0
12.0
1.000
0.01
8c
14
1.0
1.0
1.0
1.0
12.0
12.0
13.0
12.0
1.000
0.01
8d
14
1.0
1.0
1.0
1.0
12.0
12.0
14.0
12.0
1.000
0.01
9a
14
1.0
1.0
1.0
1.0
12.0
12.0
12.0
10.0
1.001
0.01
9b
14
1.0
1.0
1.0
1.0
12.0
12.0
12.0
11.0
1.001
0.01
9c
14
1.0
1.0
1.0
1.0
12.0
12.0
12.0
13.0
1.001
0.01
9d
14
1.0
1.0
1.0
1.0
12.0
12.0
12.0
14.0
1.000
0.01
More than 11,000 individual MASS observations taken at Cerro Armazones during April 2006 by the TMT T2 site testing system were used for this study. “Mag” indicates the instrument magnification. P and are the Poisson and nonlinearity parameters of the subaperture PMT. All cases were compared with the results obtained in case 1c. Δ median indicates the difference between the median of a case seeing and the median of the reference case seeing. Δ mean indicates the corresponding difference between the mean seeing of these cases. The slope was obtained by a linear fit to the seeing data, e.g., case 1a versus case 1c.
Table 2
Summary of the Sensitivity Study of the Dependence of MASS Seeing and Isoplanatic Angle on Spectral Responsea
Telescope
MASS unit
Spectral Response
ΔMedian Seeing (arc sec)
ΔMean Seeing (arc sec)
rms Seeing (arc sec)
ΔMedian (arc sec)
ΔMean (arc sec)
rms (arc sec)
T2
MD 6
without.crv
0.10
0.02
0.67
T4
MD 10
without.crv
0.07
0.21
eso_md.crv
0.08
0.08
0.06
0.16
T6
MD 8
without.crv
0.14
1.43
All numbers were obtained by comparison with the results based on the spectral response function mass.crv. To obtain these results, data taken between July and September 2006 were used, resulting in more than 7200, 10,100 and 12,100 individual data records for T2, T4, and T6, respectively.
Table 3
Main Results from the Side-by-Side Comparison of Two TMT Site Survey Instruments, T2 and T3, on Cerro Tololoa
MASS Result
Seeing (arc sec)
0.073
0.001
0.003
0.096
0.020
0.032
0.166
The results were obtained only from data for which .
Table 4
Site-by-Site Comparison Results for Data Taken between 5 and 14 September 2007a
MASS result
Seeing (arc sec)
0.05
0.04
0.11
0.07
0.02
0.06
0.10
As in Table 3, 1826 data records, for which T2 showed some vignetting. These are compared with the simultaneously obtained data taken with T3, which was not vignetted.