| Geyser | 1999-12-18 |
|---|---|
| Grand | 0335 E, 1247 E, 2253 E |
| Great Fountain | 0538 E, 1539 E |
| Values for Old Faithful Area | 1999-12-18 |
|---|---|
| Astronomical Twilight Begin | 06:09 |
| Nautical Twilight Begin | 06:44 |
| Civil Twilight Begin | 07:21 |
| Sunrise | 07:54 |
| Sunset | 16:45 |
| Civil Twilight End | 17:18 |
| Nautical Twilight End | 17:55 |
| Astronomical Twilight End | 18:30 |
| Moon Illumination | 73.82% |