| Geyser | 1999-10-17 |
|---|---|
| Grand | 0959 E, 2241 E |
| Great Fountain | 0258 E, 1237 E, 2050 E |
| Values for Old Faithful Area | 1999-10-17 |
|---|---|
| Astronomical Twilight Begin | 06:04 |
| Nautical Twilight Begin | 06:37 |
| Civil Twilight Begin | 07:11 |
| Sunrise | 07:40 |
| Sunset | 18:36 |
| Civil Twilight End | 19:05 |
| Nautical Twilight End | 19:39 |
| Astronomical Twilight End | 20:13 |
| Moon Illumination | 46.48% |