16863

The standard CTE calibration observations involve imaging starfields to assess photometric and astrometric losses as a function of observation date comma number of parallel transfers comma background comma star brightness comma etc. Like black holes comma point sources d_commahave no haird_comma --- they have no distinguishing characteristics. They can be characterized completely by the position and flux comma and as such it is easy to come up with metrics for them and model how CTE impacts these metrics. HST does indeed measure a lot of point sources comma but it also measures a lot of resolved objectsdoublePoint galaxies comma nebulae comma stars with disks comma double stars comma etc. This 1-orbit program is an effort to examine the effect of CTE on resolved objects. We will image a relatively dense galaxy field with WFC3-UVIS through the F606W filter. This filter was chosen since we can get the best S-N in the quickest time. We chose a galaxy field that was observed early in the lifetime of WFC3-UVIS comma so that we can compare present-day comma CTE-impacted observations against observations that should be largely free of CTE losses in order to investigate how much CTE affects resolved objects. The end-product of this program will be an ISR that describes how CTE affects various galaxy d_commametricsd_comma.. FWHM.. integrated light. position.. etc. We will also provide an image that shows an array of galaxy rasters and will indicate how imperfect CTE shuffles the pixel-to-pixel flux around. This should help observers to better understand their data and proposers to better understand how best to plan their observations to ensure that what they want to measure can be measured. This will also provide an interesting check on how well the pixel-based correction works on resolved objects comma which should be easier to correct than stars comma in that there is more self-shielding.