In addition to the already available imaging and TIGER modes, OASIS may be later operated in the four following modes :

• The ARGUS mode :
  
  In this mode, the micro-lens array is replaced by a bundle of optical fibers which send the light to the spectrograph stage of OASIS. This mode will give a smaller maximum field of view than the TIGER mode, but with a larger spectral range as well as a more classical data reduction software.
This mode has not yet been implemented, and its parameters are not completely defined. The resulting configurations might look like this:

Spatial resolution

F/20 AOB Sky sampling Field 0.25" 6.0" * 4.5" 0.10" 2.5" * 1.9"

F/8 CASSEGRAIN Sky sampling Field 0.64" 15" * 11"




Spectral resolution

MODE	Slit Width	R Max	Nsp (1)
ARGUS	3.8 pixel	1,330	410

(1): Number of resolved spectral elements for each mode/configuration




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• The PYTHEAS mode :
  
  This mode, a recent concept developed by Y. Georgelin and E. Lecoarer (Observatoire de Marseille), uses a Fabry-Perot etalon placed in front of the micro-lens array to increase the spectral resolution. This mode will offer the same spatial coverage as TIGER, but with a higher spectral resolution (8000 resolved spectral elements, with R < 20000).
The Pytheas mode is not yet implemented and its parameters are not fully defined. The configurations might look like this :

Spatial resolution

F/20 AOB Sky sampling Field 0.16" 6.0" * 4.8" 0.24" 9.0" * 7.2" 0.43" 16" * 13"

F/8 CASSEGRAIN Sky sampling Field 0.24" 9" * 7" 0.40" 15" * 12"




Spectral resolution

MODE	Slit Width	R Max	Nsp (1)
PYTHEAS	N.A.	20,000	8,000

(1): Number of resolved spectral elements for each mode/configuration




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• The LONG-SLIT mode :
  
  Besides a familiar feel and touch, it will offer a full coverage of the AO bonnette field with down to 0".1 spatial sampling and R < 1400.
This mode is not yet implemented, and its parameters have not been precisely defined. They may be like this :

Spatial resolution

F/20 AOB Scale Field 0.025"/pixel 0.18" * 45" 0.10" * 45" 0.060"/pixel 0.43" * 90" 0.23" * 90"

F/8 CASSEGRAIN Scale Field 0.060"/pixel 0.44" * 110" 0.24" * 110"




Spectral resolution

MODE	Slit Width	R Max	Nsp (1)
80 µm LS	3.8 pixel	1,330	410
150 µm LS	7.2 pixel	800	245

(1): Number of resolved spectral elements for each mode/configuration




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• The SCANNING FABRY-PEROT mode :
  
  In this mode, a scanning Fabry-Perot etalon is mounted in the parallel beam instead of the standard grism wheel. This mode will allow to cover the whole AOB field with spectral resolutions up to 16000 but over a very small spectral range (a few Å). Due to the scanning process, the limiting magnitude is lower than in other non-scanning modes.
This mode might look like this:

Spatial resolution

F/20 AOB Scale(1) Field 0.060"/pixel 90" dia. 0.025"/pixel 45" dia.

F/8 CASSEGRAIN Scale Field 0.062"/pixel 110" dia.

(1): with a pixel size of 15 µm



Spectral resolution

MODE	Slit Width	R Max	Nsp (2)
SFP	N.A.	20,000	16

(2): Number of resolved spectral elements for each mode/configuration

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Last update: 02/04/1998. Send comments to martin@cfht.hawaii.edu