| Geyser | 1977-08-31 |
|---|---|
| Hurricane Vent | 1800 |
| Little Whirligig | 1425 |
| Sunday | 1800 |
| Whirligig | 1440, 1535 |
| Values for Old Faithful Area | 1977-08-31 |
|---|---|
| Astronomical Twilight Begin | 05:00 |
| Nautical Twilight Begin | 05:38 |
| Civil Twilight Begin | 06:15 |
| Sunrise | 06:45 |
| Sunset | 20:01 |
| Civil Twilight End | 20:31 |
| Nautical Twilight End | 21:08 |
| Astronomical Twilight End | 21:46 |
| Moon Illumination | 93.4% |