  We studied oscillations related to flare SOL2012-09-21T02:19 in the
transition region and chromosphere based on Reuven Ramaty High Energy Solar
Spectroscopic Imager (RHESSI) and Solar Dynamics Observatory (SDO) data, as
well as data from a ground-based observatory. We found that 2-minute
oscillations triggered by the flare first appeared in the RHESSI channels then
subsequently showed up in the SDO 171 {\AA} and 304 {\AA} channels and after
that in the chromospheric He I 10830 {\AA} line. The delay of the chromospheric
signal compared to the RHESSI signal is 7 minutes, which indicates that the
wave perturbation propagated from the corona to the chromosphere. We used the
sharp increase in 3- and 5-minute oscillations during the flare in the lower
atmosphere to trace the propagation of the oscillation trains to the transition
region and corona. The results show that the 171 {\AA} channel signals lagged
behind the photospheric and chromospheric signals by 200 s on average. We
suggest that we observed slow magnetoacoustic waves both in the case of
2-minute oscillations propagating downwards from the corona and in the case of
3- and 5-minute oscillations leaking to the corona from beneath.
