| Geyser | 1999-04-20 |
|---|---|
| Great Fountain | 0838 E, 1813 E |
| Values for Old Faithful Area | 1999-04-20 |
|---|---|
| Astronomical Twilight Begin | 04:42 |
| Nautical Twilight Begin | 05:22 |
| Civil Twilight Begin | 06:00 |
| Sunrise | 06:30 |
| Sunset | 20:13 |
| Civil Twilight End | 20:44 |
| Nautical Twilight End | 21:21 |
| Astronomical Twilight End | 22:02 |
| Moon Illumination | 22.7% |