| Geyser | 1999-12-31 |
|---|---|
| Grand | 0820 E, 2008 E |
| Great Fountain | 0859 E, 2021 E |
| Values for Old Faithful Area | 1999-12-31 |
|---|---|
| Astronomical Twilight Begin | 06:14 |
| Nautical Twilight Begin | 06:49 |
| Civil Twilight Begin | 07:26 |
| Sunrise | 07:59 |
| Sunset | 16:53 |
| Civil Twilight End | 17:26 |
| Nautical Twilight End | 18:02 |
| Astronomical Twilight End | 18:38 |
| Moon Illumination | 33.45% |