| Geyser | 1999-10-21 |
|---|---|
| Grand | 0053 E, 1335 E |
| Great Fountain | 0554 E, 1555 E |
| Values for Old Faithful Area | 1999-10-21 |
|---|---|
| Astronomical Twilight Begin | 06:09 |
| Nautical Twilight Begin | 06:42 |
| Civil Twilight Begin | 07:16 |
| Sunrise | 07:45 |
| Sunset | 18:29 |
| Civil Twilight End | 18:59 |
| Nautical Twilight End | 19:33 |
| Astronomical Twilight End | 20:06 |
| Moon Illumination | 83.64% |