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Moderate flux rises of 6.668-GHz CH3OH maser related to the H2O maser bursts in G 025.65+01.05 using the Hitachi 32-m

ATel #10757; Koichiro Sugiyama (National Astronomical Observatory of Japan), Yu Saito, Hiroshi Akitaya, Yoshinori Yonekura, and Munetake Momose (Ibaraki University)
on 19 Sep 2017; 09:03 UT
Credential Certification: Koichiro Sugiyama (koichiro.sugiyama@nao.ac.jp)

Subjects: Radio, Variables, Young Stellar Object

Referred to by ATel #: 10788, 10842, 10853

A moderate flux rise has been confirmed in 6.668-GHz CH3OH maser in the star-forming region G 025.65+01.05 at least from three months in advance of the H2O maser burst (Volvach and Volvach, et al. 2017, ATel #10728): from 104.1 to 146.5 Jy during 2017 Jun 14 - 2017 Sep 10 in the brightest spectral feature at Vlsr = 41.9 km/s, yielding an average of 124.2 Jy with a standard deviation of 9.2 Jy. Using the Hitachi 32-m radio telescope, we have initiated a flux monitor observation of the CH3OH maser in G 025.65 since 2013 Jan 02 with an interval of 9-10 days till 2014 Jan 06, and daily from 2014 May 07. The brightest spectral feature showed moderate flux rises at least eight times: from 77.8 Jy to 184.7 Jy during 2013 Jan 02 - 2017 Sep 10, yielding an average of 132.2 Jy with a standard deviation of 20.4 Jy. The moderate flux rise has been observed in advance of the previous H2O bursting phase 2016 Nov-Dec, too: from 122.7 to 181.6 Jy during 2016 Aug 01 - 2016 Nov 01, yielding an average of 143.5 Jy with a standard deviation of 12.3 Jy. Note that the flux monitor using the Hitachi 32-m took a rest during 2017 Mar 08 - 2017 Jun 13 due to the maintenance.