difference image concerns:

• normalizations:
  • are they correct?
  • significant coupling between normalization and other kernel terms
• ringing -- there is significant ringing left behind in difference of images with PS1_V1 PSF shapes
  • is the basis function able to represent the actual observed differences sufficiently?
  • is the observed ringing the result of the coupling to the normalization?
  • is the observed ringing due to the degeneracy between basis terms?
• basis function orthogonality
  • does the non-orthogonal nature of the Alard-Lupton kernels increase sensitivity to noise and false positives?
  • can we choose a more-orthogonal basis set?
• span of basis set
  • how can we choose a set of kernels that spans a sufficient range?
  • can the Alard-Lupton basis set cover a wide enough range of structures?
• weighting?
• windowing?
• dual convolution -- strange results with power going to non-radial terms

Some specific bugs identified

• normalizations were failing for 1D convolutions

• the wrong preCalc element was being used in a certain context related to Dual

• the peak pixel is rediscovered, changing the center by 1 pixel for well-centered stars (this is not technically a bug, but makes it difficult to interpret the chi-square images)