A Novel Radio-Frequency Interference Flagging Technique for Radio-Interferometric Data from the Murchison Widefield ArraydissertationsKunicki, Theodora ColecreatorPober, JonathanAdvisorTucker, GregoryReaderdell'Antonio, IanReaderBrown University. Department of Physicssponsor202416, 80 p.born digitalThesis (Ph. D.)--Brown University, 2024thesesRadio-frequency interference detection and flagging is one of the most difficult and urgent problems in 21 cm Epoch of Reionization research. In this work, we present χ^2 from redundant calibration as a novel method for RFI detection and flagging, demonstrating it to be complementary to current state-of-the-art flagging algorithms. Beginning with a brief overview of radio interferometry and an overview of the Murchison Widefield Array, we then continue into a discussion of redundant calibration and the meaning of the χ^2 metric, finally demonstrating a two-step RFI flagging algorithm which uses the values of this metric to detect faint RFI. We find that roughly 27.4% of observations have RFI from digital television channel 7 detected by at least one algorithm of the three tested: 18.0% of observations are flagged by the novel χ^2 algorithm, 16.5% are flagged by SSINS, and 6.8% are flagged by AOFlagger (there is significant overlap in these percentages). Of the 27.4% of observations with detected DTV channel 7 RFI, 37.1% (10.2% of the total observations) are detected by χ^2 alone, and not by either SSINS or AOFlagger, demonstrating a significant population of as-yet undetected RFI. We find that χ^2 is able to detect RFI events which remain undetectable to SSINS and AOFlagger, especially in the domain of long-duration, weak RFI from digital television. We also discuss the shortcomings of this approach, and discuss examples of RFI which seems undetectable using χ^2 while being successfully flagged by SSINS and/or AOFlagger.Radio interferometersRadio--InterferenceEnglishRPB20241015