the gsm: a dedicated monitor for wavefront optical parameter measurements
DESCRIPTION
GSM working layout at La Silla (Chile) Sept. 1997. The GSM: a dedicated monitor for wavefront optical parameter measurements. A. Ziad, F. Martin, R. Conan, J. Borgnino. Summary. Presentation of the GSM Principle Configuration and optical device Atmospheric optical parameters (AOP) data - PowerPoint PPT PresentationTRANSCRIPT
The EOS/SPIE Symposium on Remote Sensing - Sept. 1999 - Florence
A. ZiadDépartement d’Astrophysique - Parc Valrose - 06108 NICE Cedex 2 - France
The GSM: a dedicated monitor for wavefront
optical parameter measurements
GSM working layout at La Silla (Chile) Sept. 1997
A. Ziad,
F. Martin,
R. Conan,
J. Borgnino.
The EOS/SPIE Symposium on Remote Sensing - Sept. 1999 - Florence
2
A. ZiadDépartement d’Astrophysique - Parc Valrose - 06108 NICE Cedex 2 - France
Summary
Presentation of the GSM Principle Configuration and optical device
Atmospheric optical parameters (AOP) data Data of the outer scale L0, seeing and isoplanatic
angle measured at different sites over the world:
La Silla, Pachon, Paranal (Chile), Oukaïmeden (Morocco) and Maydanak (Uzbekistan)
The EOS/SPIE Symposium on Remote Sensing - Sept. 1999 - Florence
3
A. ZiadDépartement d’Astrophysique - Parc Valrose - 06108 NICE Cedex 2 - France
Presentation of the GSM
GSM is equipped with 4 telescopes : each one measures synchronously the angle of arrival (AA) of the wavefront spatial covariance L0 differential variance
scintillation
spatio-temporal correlation
GSM working layout at La Silla (Chile) Sept. 1997
The EOS/SPIE Symposium on Remote Sensing - Sept. 1999 - Florence
4
A. ZiadDépartement d’Astrophysique - Parc Valrose - 06108 NICE Cedex 2 - France
The GSM optical device
)(tan2
1 1
CA
BD
The EOS/SPIE Symposium on Remote Sensing - Sept. 1999 - Florence
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A. ZiadDépartement d’Astrophysique - Parc Valrose - 06108 NICE Cedex 2 - France
GSM campaigns
GSM is operational since 2 years and different sites over the world has been visited
La Silla, Pachon, Paranal (Chile) Oukaïmeden (Morocco) Maydanak (Uzbekistan)
The EOS/SPIE Symposium on Remote Sensing - Sept. 1999 - Florence
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A. ZiadDépartement d’Astrophysique - Parc Valrose - 06108 NICE Cedex 2 - France
Typical one night measurements
L0med = 45.3 m
0med = 0.99’’
0med = 1.7’’
The EOS/SPIE Symposium on Remote Sensing - Sept. 1999 - Florence
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A. ZiadDépartement d’Astrophysique - Parc Valrose - 06108 NICE Cedex 2 - France
GSM/DIMM comparison
Surface layer effect:
GSM was installed at a height of 1.7 m.
DIMM was installed at a height of 5 m.
Exposure time effect:
5 ms for GSM 10 ms for DIMM
The EOS/SPIE Symposium on Remote Sensing - Sept. 1999 - Florence
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A. ZiadDépartement d’Astrophysique - Parc Valrose - 06108 NICE Cedex 2 - France
Effect of the exposure time
Linear extrapolation is done to evaluate the differential variance at the origine
d2(0ms) = 2 d
2(5ms) - d2(10ms)
The EOS/SPIE Symposium on Remote Sensing - Sept. 1999 - Florence
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A. ZiadDépartement d’Astrophysique - Parc Valrose - 06108 NICE Cedex 2 - France
L0, & resultsLa Silla (Chile) Aug. 28 - Sept. 18 1997
L0med = 25 m
0med = 1.68’’
0med = 1.26’’
The EOS/SPIE Symposium on Remote Sensing - Sept. 1999 - Florence
10
A. ZiadDépartement d’Astrophysique - Parc Valrose - 06108 NICE Cedex 2 - France
L0, & resultsOukaïmeden (Morocco) April 10-25
1998
L0med = 32 m
0med = 1.33’’
0med = 1.50’’
The EOS/SPIE Symposium on Remote Sensing - Sept. 1999 - Florence
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A. ZiadDépartement d’Astrophysique - Parc Valrose - 06108 NICE Cedex 2 - France
L0, & resultsMaydanak (Uzbekistan) July 16-24 1998
L0med = 26 m
0med = 0.66’’
0med = 2.48’’
The EOS/SPIE Symposium on Remote Sensing - Sept. 1999 - Florence
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A. ZiadDépartement d’Astrophysique - Parc Valrose - 06108 NICE Cedex 2 - France
L0, & resultsCerro Pachon (Chile) Oct. 1-10 1998
L0med = 27 m
0med = 0.83’’
0med = 2.82’’
The EOS/SPIE Symposium on Remote Sensing - Sept. 1999 - Florence
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A. ZiadDépartement d’Astrophysique - Parc Valrose - 06108 NICE Cedex 2 - France
L0, & resultsParanal (Chile) Nov. 26 - Dec. 21 1998
L0med = 22 m
0med = 0.88’’
0DIMM = 0.87’’
0med = 1.9’’
The EOS/SPIE Symposium on Remote Sensing - Sept. 1999 - Florence
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A. ZiadDépartement d’Astrophysique - Parc Valrose - 06108 NICE Cedex 2 - France
Data summary
Site Date Seeing 0 (as) Outer scale L0 (m) Isoplanatic angle 0 (as)
La Silla (Chile) 08/26/97 - 09/20/97 1.68 +/- 0.47 24.8 +/- 19.3 1.26 +/- 0.42
Oukaimeden (Morocco) 04/10/98 - 04/25/98 1.33 +/- 0.90 31.1 +/- 34,8 1.50 +/- 0.69
Maydanak (Uzbekistan) 07/16/98 - 07/25/98 0.66 +/- 0.25 25.9 +/- 19.0 2.48 +/- 0.70
Cerro Pachon (Chile) 10/02/98 - 10/09/98 0.83 +/- 0.46 26.7 +/- 3.5 2.82 +/- 0.97
Paranal (Chile) 11/27/98 - 12/20/98 0.88 +/- 0.40 22.1 +/- 33.9 1.90 +/- 0.69
The EOS/SPIE Symposium on Remote Sensing - Sept. 1999 - Florence
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A. ZiadDépartement d’Astrophysique - Parc Valrose - 06108 NICE Cedex 2 - France
Temporal stability of the AOP
For an error of 5%, the change time is:
for the outer scale: 1.6 mn for the seeing: 9.2 mn for the isoplanatic angle: 4.6
mn
)()(
)()(
tXttX
tXttXNDX
The EOS/SPIE Symposium on Remote Sensing - Sept. 1999 - Florence
16
A. ZiadDépartement d’Astrophysique - Parc Valrose - 06108 NICE Cedex 2 - France
Conclusion
GSM is operational since 2 years 5 campaigns:
La Silla, Cerro Pachon, Paranal (Chile), Oukaïmden (Morocco) and Maydanak (Uzbekistan).
Important databank of the different sites over the world: Study of the temporal variability of the AOP and their
prediction via a modelization to optimize the HAR observations
Results on the Web: http://www-astro.unice.fr/GSM