Development of cross-correlation spectrometry and the coherent structures of maser sources

Abstract

Abstract We have developed a new method of data processing for radio telescope observation data to measure time-dependent temporal coherence, and we have named it “cross-correlation spectrometry” (XCS). XCS is an autocorrelation procedure that expands time lags over the integration time and is applied to data obtained from a single-dish observation. The temporal coherence property of received signals is enhanced by XCS. We tested the XCS technique using the data of strong H2O masers in W 3 (H2O), W 49 N, and W 75 N. We obtained the temporal coherent lengths of the maser emission to be 17.95 ± 0.33 μs, 26.89 ± 0.49 μs, and 15.95 ± 0.46 μs for W 3 (H2O), W 49 N, and W 75 N, respectively. These results may indicate the existence of a coherent astrophysical maser.