Star mapper residuals distribution

Two type of charts are shown here, the distribution of actual residuals, and the distribution of normalized residuals. In both cases charts are shown for the vertical slits, and for the chevron slits in each of the fields of view.

The distribution of actual residuals shows that the majority of the observations have standard errors of a few tens of mas (see figure below for the chevron slits). The errors for the vertical slits are significantly smaller than for the chevron slits.

SM residuals chevron

The normalized residuals show a wider distribution than expected, indicating that the standard errors are slightly underestimated. This is a problem inherent to fitting to predicted single-slit profiles, and is due to the difficulty to predict the exact profile applicable to the observation.

SM Normalized residuals vertical