Method for Finding Variable Radio Sources in Drift-Scan Interferometric Data from the Nasu Observatory

ABSTRACT We have developed an analysis method for finding flux variabilities of the fringes in drift-scan interferometric data at 1.4 GHz obtained from the Nasu observatory. This method uses the expectation data of the Nasu observation generated from a radio sky survey catalog at 1.4 GHz, such as the NRAO VLA Sky Survey (NVSS) catalog. The variabilities are detected by comparing the power scales of the fringes in the observation data with those in the expectation data. A difference in both data fringe scales indicates the possible presence of variabilities. By using the technique described above, we analyzed the Nasu drift-scan survey results at δ = 32.5° ± 0.3°. Thus, we succeeded in finding the fringe variabilities in the data. This result indicates that our method is effective in detecting fringe variabilities in the Nasu interferometric data.