Determine whether the ACIS-I spatial contamination model requires adjustment

Determine whether the spatial model for the contamination layer on the ACIS-I array requires adjustment to account for the decrease in the E0102 Ne X Ly-alpha line normalization at low chipy, where the contamination layer is thickest.

Background

The E0102 calibration measurements show a downward trend in the Ne X Ly-alpha line normalization at low chipy on the ACIS-I I3 CCD. Because the contaminant is thickest in this region, the trend may indicate that the assumed spatial distribution of contamination is inaccurate.

The paper does not resolve whether the observed behavior is caused by an inadequacy in the ACIS-I spatial contamination model, leaving its possible adjustment as an explicitly identified unresolved problem.

References

The decrease in the E0102 \ion{Ne}{x}~Ly$\alpha$ line normalization at low chipy on I3 where the contaminant is thickest might indicate that the spatial model needs adjustment on the ACIS-I array.

— The Evolution of the ACIS Contamination Layer on the Chandra X-ray Observatory from 2010 to 2026  (2608.14363 - Plucinsky et al., 14 Aug 2026) in Section 5, Conclusions