def calc_t_exp(n_int, t_ramp):
    """Calculates exposure time (or photon collection duration as told by APT.)

    Parameters
    ----------
    n_int : int
        Integrations per exposure.
    t_ramp : float
        Ramp time (in seconds).

    Returns
    -------
    t_exp : float
        Exposure time (in seconds).
    """

    t_exp = n_int*t_ramp
    return t_exp