To measure changes in the CTE of the Red CCD, we examine the cosmic ray detections in a 900 or 1200 second dark. Scripts are used to identify relatively linear cosmic rays in a dark. For each cosmic ray a gaussian is fit to the distribution along the x axis. We then attempt to clean the data by flagging data that is more than 2.5 sigma from the median value per pixel postion. Five passes with the sigma cut are made to flag "bad" values. Bad values are plotted as the darker color. Good values are white in the plots below. We then make one more gaussian fit (colored line) to the data.
The two white line below the plots indicate the regions where the median is determined on either side of the fit gaussian. See the second graph below.
Archived graphs are found in ../data/archive_cte/
Here we try to measure the sigma of the a fitted gaussian. The assumption is that if the CTE worsens there will be a tail in the row in the readout direction and a fitted gaussian will have a larger FWHM to compensate. As the CTE worsens we should see a trend of increasing sigma over time. For the measured FWHM see table
In the plot below, we measure the difference of the flux found in the wings. The assumption is that if the CTE worsens there will be a tail in the row in the readout direction. If this occurs there will be more excess flux in the wing on one side of a gaussian and the absolute value of the difference of the medain value in the wing will increase. In the top graph the white lines under the gaussian fits indicate where the median is calculated. The raw values for this graph may be found at: table