# forge.ta.period_open

```python
forge.ta.period_open(open_: ArrayLike, time_open: ArrayLike, period: str = 'D', day_boundary: str = '17:00 America/New_York') -> np.ndarray
```

The open of the current day, week or month on every bar of it.

The value is known on the first bar of the period. A period already under way at the first bar
of the data has no value. ``time_open`` is in nanoseconds (UTC) and must be in time order.

Since Forge API 1.