| Geyser | 1999-12-21 |
|---|---|
| Grand | 0038 E, 1129 E, 2214 E |
| Great Fountain | 0811 E, 1754 E |
| Values for Old Faithful Area | 1999-12-21 |
|---|---|
| Astronomical Twilight Begin | 06:10 |
| Nautical Twilight Begin | 06:46 |
| Civil Twilight Begin | 07:23 |
| Sunrise | 07:56 |
| Sunset | 16:46 |
| Civil Twilight End | 17:19 |
| Nautical Twilight End | 17:56 |
| Astronomical Twilight End | 18:32 |
| Moon Illumination | 96.79% |