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Aims: We have analyzed low frequency radio data of tidal disruption event(TDE) Swift J1644+57 to search for a counterpart. We consider how brieftransient signals (on the order of seconds or minutes) originating from thislocation would appear in our data. We also consider how automatic radiofrequency interference (RFI) flagging at radio telescope observatories mightaffect these and other transient observations in the future, particularly withbrief transients of a few seconds duration.  Methods: We observed the field in the low-frequency regime at 149 MHz withdata obtained over several months with the Low Frequency Array (LOFAR). We alsopresent simulations where a brief transient is injected into the data in orderto see how it would appear in our measurement sets, and how it would beaffected by RFI flagging. Finally, both based on simulation work and theweighted average of the observed background over the course of the individualobservations, we present the possibility of brief radio transients in the data.  Results: Our observations of Swift J1644+57 yielded no detection of thesource and a peak flux density at this position of 24.7 $\pm$ 8.9 mJy. Ourupper limit on the transient rate of the snapshot surface density in this fieldat sensitivities < 0.5 Jy is $\rho < 2.2 \times10^{-2}$ deg$^{-2}$. We alsoconclude that we did not observe any brief transient signals originatingspecifically from the Swift J1644+57 source itself, and searches for suchtransients are severely limited by automatic RFI flagging algorithms which flagtransients of less than 2 minutes duration. As such, careful consideration ofRFI flagging techniques must occur when searching for transient signals.

LOFAR Observations of Swift J1644+57 and Implications for Short-Duration Transients