Ultra-precise monitoring of a class I methanol maser

M. A. Voronkov, S. L. Breen, S. P. Ellingsen, J. A. Green, A. M. Sobolev, S. Yu Parfenov, D. J. Van Der Walt

Research output: Contribution to journalArticlepeer-review


We report the results of a 7-year monitoring program using the Australia Telescope Compact Array (ATCA) for the 9.9 GHz class I methanol maser in G331.13-0.24 where a periodic class II methanol maser is present. The great deal of the project was to control systematics at an unprecedented level. Although no periodic flux variation was found, the maser shows a very stable decline of 166±7 Jy/day. The radial velocity of the maser is stable down to 1 m/s level. We also report a marginal periodic signal in radial velocity (comparable to the level of systematics) of about 20±7 cm/s with the period of 475±22 days, close to that of the 6.7-GHz maser in the source. No hyperfine split was detected which suggests preferential excitation of a single hyperfine transition.

Original languageEnglish
Pages (from-to)255-257
Number of pages3
JournalProceedings of the International Astronomical Union
Publication statusPublished - 7 Dec 2022
Externally publishedYes


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