WFS Readnoise

While the NAS was mounted on the telescope we took a quick set of readnoise measurements with the CCD39. Here are the results. The only major caveat is that the telescope was not tracking, so we didn’t test whether the drives have any impact. Otherwise, this is the most realistic set of RON measurements we have taken to date. We are very happy with the results, especially the 156kHz 3.8 electrons. This number essentially sets the limit to how faint our guide star can be, so keeping it low is important.

Pixel Rate (kHz) Frame Rate (fps) RON (e-)
156 80 3.8
400 197 5.8
900 893 8.4
2500 1053 10.2

Note: these are determined using the actual gains from Scimeasure, rather than assuming 0.5. This can cause as much as an 8% difference.