Every miniCBF sweep was handed the same hardcoded axis regardless of what its header said, and
Chi/Kappa/Phi/Omega were not parsed at all - there were no members for them. A sweep collected on a
tilted chi cradle therefore ran with an axis that is 54.7 degrees wrong.
The header angles and their increments are now read, the scanned axis is identified from the
non-zero increment (the name is consulted only when no increment is stated, which is what absorbs the
five different spellings the corpus contains, including one file that states no axis name at all),
and a phi scan composes the head chain. An omega scan returns the base axis untouched, because a
fixed chi cannot tilt the axis it hangs from.
-9999 is a sentinel meaning "not set", not an angle. It is treated as absent, so it can never reach
the geometry.
The direction and sense are not invented: these files append an imgCIF _axis loop stating their own
vectors, and SOURCE with GRAVITY fix the imgCIF-to-internal transform, which independently reproduces
the transform this repository already documents for NXmx. Under it the file's own stated phi axis is
exactly the composed one, to four decimals.
Driving the real reader over all 39 corpus sweeps, 37 return the previous axis bit-identically -
including every sweep carrying a large fixed chi, every sentinel header and every axis-name spelling.
Only the two genuine phi scans move, and an unrelated rotation dataset is unchanged end to end.
This is necessary but not sufficient for the one dataset that motivates it: with the axis corrected
it still does not index, because that detector is also mounted rotated 90 degrees in its own plane,
which the reader does not yet read. Compensating both takes its phi sweep from no indexed validation
frames to 90.89% indexed and a complete merge, which is what shows this half is load-bearing. The
detector mount and the two-theta swing belong to the detector-frame work.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Lc5JG6kJqZoCWaoZ43JGTW
leonarski_fandClaude Opus 5
367eba55b1