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GMOS OIWFS

The GMOS On-instrument Wavefront Sensor (OIWFS) consists of a 2x2 lenslet array on a moveable arm that patrols an area in front of the mask plane. Signals from the OIWFS are fed to the secondary for fast tip-tilt guiding.

The peripheral WFSs (PWFS) vignet a large part of the GMOS science field. Further, there is significant flexure between GMOS and the PWFSs, thus the PWFSs should not currently be used with GMOS.

OIWFS detector parameters
Array EEV CCD-39
Pixel format 80x80
Pixel size 24 micron pixels
Spectral Response 0.37 at 450nm, 0.70 at 700nm, 0.41 at 900nm
Readout time 4.71ms for full frame
Readnoise 3.05e-/pix
Total noise (on telescope during observations) 5.95e-/pix
Dark current (uncooled) 28.2 e-/s/unbinned pixel

Schematic drawing of the OIWFS arm in front of the mask plane in GMOS.


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In original form; Isobel Hook
Last update August 27, 2003; Kathy Roth