Crosstalk correction for WFC3/UVIS

[pllim]

Fix #701

Close #705

Python version

    # Split amps.
    a = ab[:, :2048]
    b = ab[:, 2048:]
    c = cd[:, :2048]
    d = cd[:, 2048:]

    # Pull constants and slopes
    # (slopes were divided by 1000 on load)
    const_a, const_b, const_c, const_d = consts
    slope_a, slope_b, slope_c, slope_d = slopes

    # Apply correction.
    a_corr = a - (const_a + np.flip(b, 1)*slope_a)
    b_corr = b - (const_b + np.flip(a, 1)*slope_b)
    c_corr = c - (const_c + np.flip(d, 1)*slope_c)
    d_corr = d - (const_d + np.flip(c, 1)*slope_d)

    # Initialize array out
    ab_out, cd_out = ab, cd

    # Fill in amps
    ab_out[:, :2048] = a_corr
    ab_out[:, 2048:] = b_corr
    cd_out[:, :2048] = c_corr
    cd_out[:, 2048:] = d_corr

amp,const,slope
A,0.0180206,-0.060494304
B,0.15501201,-0.20746221
C,-0.038376406,-0.079701178
D,0.19124641,-0.23177171

TODO

• Fix build errors
• After BIASCORR (superbias subtracted)
• Full-frame only
• Not binned
• Convert to electrons (see gain correction in flatfield step) before cross-talk correction, then convert back to DN
• Propagate error (ask Norman how, sqrt of corrected sci.data?)
• See how WFC3 ISR 2012-02 coefficients fit into this algorithm
• Try to understand why it is not really working
  • Promote calculations to double
  • OMG there is a slope/1000 in the Python script that I missed 😭
• Seek INS feedback
  • Open alternate PR to "keep the intercept term, but applying a max(0, ...) bound to the correction" -- See Crosstalk correction for WFC3/UVIS (alternative) #705
• Implement alternate correction route for PCTECORR=PERFORM. This would be done after special bias correction and unit conversion within CTE algorithm but before the CTE correction. Then, the correction after BIASCORR would only be for PCTECORR=OMIT. This part is blocked by WFC3: Implementation of an x-CTE correction in CALWF3 for UVIS #666

RT:

• https://github.com/spacetelescope/RegressionTests/actions/runs/21933025592
• https://github.com/spacetelescope/RegressionTests/actions/runs/21963575590 (zero intercepts)