What discoveries have come from the DASCH project (Digital Access to a Sky Century @ Harvard)
The most notable one I'm aware of is the detection of the secular dimming of Boyajian's Star (KIC 8462852), as described in Schaefer (2016). Follow-up by Schaefer et al. (2018) suggest that the ratios of the dimming across the BVRI bands are consistent with dust, though the reason for the lack of detectable infrared excess remains unknown.

DASCH data has also been used to constrain the orbital period of the ringed object transiting J1407, see Mentel et al. (2018). The DASCH plates did not show any previous transit in the data, ruling out a large fraction of orbital periods and opening the possibility that the ringed object J1407b may not be gravitationally bound to J1407.