The reported sigma carries the background ring mean's own error as
(dI/dbkg)^2 * bkg/n_ring, and the stills ring holds only 244 pixels at
r3 = 12 against the rotation default's 408 - so that term is a larger
share of the variance here than anywhere else in the program. r3 = 14
takes the ring to 416.
What normally stops a ring being widened is crowding, since a neighbour
inside the annulus is excluded from it. Stills barely crowd: neighbour
occlusion is 0.000% at both radii on six of the seven datasets scored and
0.721% -> 0.678% on the densest, against most reflections having a
neighbour within 13 px on rotation. Rotation is left alone at 4,6,13,
where the ring already wins by a factor of several.
Measured with the new stills harness over six datasets and 72 shells,
10000 images each, resolution range pinned so both arms share shell
edges, against a control floor that is bit-identical in every column:
<I/sigma> +1.23% median over the 56 signal-bearing shells (44/56)
R_meas -0.37 points (39/56)
CC1/2 flat (29/56)
obs flat
R_meas is the number to read here. <I/sigma> improving when the ring is
widened is half mechanical - a better background estimate lowers sigma by
construction - whereas R_meas has no sigma in it, so it moves only if the
intensities themselves got better. A prediction from ring pixel counts
alone, made before the run, was 1.6-2.7%; landing at 1.2% with the
profile-fit weighting in the way is the mechanism behaving as expected.
The larger and more consistent effect is the opposite of the risk this
was checked against: reflections discarded for want of a background ring
fall from 2.53-2.88% to 1.87-2.25% on all seven datasets, because a wider
ring reaches past the module gap that starved the narrow one.
Against it: CC1/2 and observation count are flat, and the gain reverses
below <I/sigma> of about 4 - median -0.4% and -0.6% in the two weakest
bands. Roughly a fifth of that is background curvature, which
--background-radial recovers; the rest is not explained.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CHMmeM1d489zvNFT7ZMN2P
leonarski_fandClaude Opus 5
c4f4f7e28f
