ObjID515-1
‹ Ancient Sundials
Dialface ID 558
Abstract
Information on the Dialface ID 558 / Object ID 515
Measurements
Measurement record: pipeline ObjID 515, matched to this dialface by inventory number.
| Quality grade | C (completeness 90 %) |
|---|---|
| Dial surface | sphere (decisive) · fit residual mm: cone 0.53, cylinder 1.34, sphere 0.18 |
| Latitude φ | 27.51 ± 5.08° (consensus of witnesses) |
| Klima | Syene (II), Alexandria (III), Rhodes (IV) |
| Engraved lines | 5 hour lines, 3 day lines |
| Cone half-angle α | not shown: surface fit decisively sphere: cone-specific quantities do not apply |
| Measured | 2026-06-12 20:55 |
What the dial shows at this latitude
| Winter solstice | Equinox | Summer solstice | |
|---|---|---|---|
| Noon altitude of the Sun | 38.8° | 62.5° | 86.2° |
| Noon shadow (gnomon heights) | 1.25 | 0.52 | 0.07 |
| Length of the day | 10.2 h | 12.0 h | 13.8 h |
| Length of a seasonal hour | 51 min | 60 min | 69 min |
Computed for the measured latitude with the obliquity of the JPL ephemeris at 101 BC (year -100). The latitude is the one the dial was made for, not a find-spot coordinate.
References
3D Models
