| Geyser | 1991-05-15 |
|---|---|
| Echinus | 1536, 1627 |
| Pearl | 1200 |
| Whistle | 1991-05-12 0000-1991-05-24 0000 |
| Values for Old Faithful Area | 1991-05-15 |
|---|---|
| Astronomical Twilight Begin | 03:49 |
| Nautical Twilight Begin | 04:39 |
| Civil Twilight Begin | 05:22 |
| Sunrise | 05:55 |
| Sunset | 20:43 |
| Civil Twilight End | 21:17 |
| Nautical Twilight End | 21:59 |
| Astronomical Twilight End | 22:49 |
| Moon Illumination | 1.63% |