# C253 — The final 1250 interval has same-Gear Noah/Flood endpoints

23 September 2026 · Step 48 of 60, continuing C205.

The final 13-fold SP Noah endpoint and the new double-11 MT Flood endpoint have the same Gear in all six admitted rows. Primary Noah pairs with Flood start; companion Noah pairs with Flood close. Their span is always 1250=2×625.

| Gear | SP Noah rail | MT Flood state | Flood center | Noah center | Width |
|---|---|---|---|---|---|
| 1 | companion | Flood close | 2455 | 3705 | 1250 |
| 1 | primary | Flood start | 2456 | 3706 | 1250 |
| 2 | companion | Flood close | 2457 | 3707 | 1250 |
| 2 | primary | Flood start | 2458 | 3708 | 1250 |
| 3 | companion | Flood close | 2459 | 3709 | 1250 |
| 3 | primary | Flood start | 2460 | 3710 | 1250 |

For the primary rows this is the sourced 600-year MT Noah-to-Flood interval plus the 650-year SP–MT Noah displacement. Moving both terminal points one year earlier preserves 1250 for companion/close rows. That explanation does not introduce an MT Noah companion event at the internal join.

## Evidence and scope

K=529 and r=25/23. BC base B means (B+1)t/Bn BC; reflected AD base A means AD At/(A+1)n. Their civil span is B+A in both seasonal components, with no year zero. Signed paired centers are −B and +A; the center model uses components ±1/4 and restores this separation after dilation. An interval center is geometry, not an event or a proposed universal Mirror axis.

Regular Gears are restricted to Noah/Shem/Flood. Creation and Conquest retain fixed source-field members; no fourth Gear is admitted. Generated coordinates, source-field membership and stored graph incidence are distinct. File_18/File_09 and the frozen C127 graph are unchanged. Earlier N01/N03 qualifications, the missing Shem join, closed primers and unestablished original Reports 11–25 remain unchanged. This packet selectively uses prior evidence; it does not rerun completed campaigns. Assertions and alternative placements are not independent historical witness counts.

**24 step-specific checks and 19 frozen-input checks passed.** Exact inputs, results and predecessor hashes are in the accompanying JSON records; calculation code is in the evidence archive. Source dependencies are identified in the body and frozen in `sources/`.