How this was made
The LM’s alignment optical telescope (AOT) is a periscope fixed to the LM. It can be turned to six positions, called detents, 60° apart around the LM’s vertical axis, each looking 45° up from the horizontal, with a 60° field. The crew used it on the surface to realign the guidance platform.
- Which figure this is. TN D-6853 Fig 4 reproduces the Apollo 11 note’s Fig 10.0-2, “2 hours after lunar landing”. The note’s planned touchdown is powered descent at 102:35:40 plus the 692-second burn, 102:47:12 ground elapsed time, so these views are at 104:47:12. (Fig 10.0-3, the “2 hours before lift-off” set, fits badly: at that time the LM would have to lean 9.6° to match.)
- The LM’s attitude is not printed. It was fitted on panel (a) only (7 bodies, 0.34° RMS) and then frozen. The result is physically sensible: the LM’s vertical axis is 1.4° from local vertical, it faces 269.3° (due west, the planned landing heading), and its axes lie within 0.6° of the 1969 note’s Lunar landing site REFSMMAT, the guidance reference aligned to the landing site.
- The image turns with the telescope head. As in any rotating-head periscope, turning the head to a detent rotates the image by the detent angle. The 1969 program drew each view’s reticle cross rotated by exactly that amount (−60°, −120°, … measured on the scans), which fixes the direction of the rotation.
Result
Predicted from the panel-(a) attitude with nothing further fitted:
| Panel | RMS | Worst | Target (RMS ≤ 1°, worst ≤ 2°) |
|---|---|---|---|
| (b) left front | 1.02° | 1.36° | missed (by 0.02°) |
| (c) left rear | 1.90° | 3.53° | missed |
| (d) rear | 0.97° | 1.54° | met |
| (e) right rear | 1.26° | 2.25° | missed |
| (f) right front | 0.98° | 1.69° | met |
The targets were set before any panel was measured, and they are reported as they came out. Two things account for the roughly 1° level:
- Calibrating the attitude on one panel of seven bodies leaves a small attitude error. Using the other five panels instead predicts each held-out panel at about 0.7–1.0° RMS, except (c).
- Panel (c) is the hardest to measure: four of its glyphs sit on drawn lines.
Limits
- The shaded crescents in the originals (the parts of the view blocked by the LM’s structure, including the antenna) are not drawn.
- The observer is the Moon’s center, not the landing site (a difference under 0.3° for Earth).
- In panel (f) Deneb is drawn as a plain dot rather than the navigation-star asterisk. It was taken as the dot directly above its label.
- In panel (e) the recreation draws Menkar and the Sun near the lower corners (both above the lunar horizon, at 77° and 12° elevation), but the 1969 plot omits them. Its rule for choosing which objects near the frame corners to draw is not documented.