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Seeing limited NIFS IFU spectroscopy

In addition to the adaptive optics-fed mode, NIFS has also been commissioned to be used with the Peripheral Wavefront Sensor, PWFS2. The NIFS field will be vignetted by the PWFS2 probe arm using stars that are closer to the science target than ~3.8 arcminutes. The outer limit for PWFS2 guide stars can be displayed on the OT position editor and is discussed here. More information on the Peripheral Wavefront Sensor vignetting regions and information on how to define PWFS2 guide stars can be found in the OT help pages .

Extensive flexure modeling of the NIFS+PWFS2 system has not been done, but we presume that guiding with NIFS in this mode will provide performance similar to the NIRI+PWFS2 observations (roughly 0.1" of flexure per 30-45 minutes of on-sky observations, depending on the elevation and rotator position). It is not presently possible to use the NIFS OIWFS guide stars to compensate for flexure when observing with PWFS2.

Required Guide Star Characteristics: See the table on the main guiding options page for limiting guide star magnitudes for PWFS2.