Report of the Daily Monitor of Sgr A* at 22 GHz
ATel #5184; M. Tsuboi, Y. Asaki(ISAS/JAXA), Y. Yonekura(Ibaraki Univ.), H. Kaneko, Y. Miyamoto, M. Seta, N. Nakai (Univ. of Tsukuba), O. Kameya, M. Miyoshi(NAOJ), H. Takaba, K. Wakamatsu (Gifu Univ.), Y. Fukuzaki(GSI), T. Morimitsu(Univ. of Tokyo), M. Sekido(NICT), T. Oka, S. Takekawa(Keio Univ.), T. Omodaka, T. Handa(Kagoshima Univ.) and A. Takumi(OUJ)
on 2 Jul 2013; 01:25 UT
Credential Certification: Masato TSUBOI (tsuboi@vsop.isas.jaxa.jp)
Subjects: Radio, Black Hole, Transient
We have been monitoring Sgr A* at 22 GHz since Feb. 2013 with
a sub-array of Japanese VLBI Network (ATEL#4923, #5013).
The sub-array consists of
Mizusawa 10-m RT, Takahagi 32-m RT, and Gifu 11-m RT.
Tsukuba 32-m RT had joined it a few times.
Because the baselines are a few or several 100 km, the sub
-array can observe the flux density of Sgr A* itself avoiding the
contamination from extended structure surrounding Sgr A* and the
flux density decrease by partially resolved-out.
The observations are performed almost daily except rainy day although
the observation time of Sgr A* is only 10 minute.
The (preliminary) results of the monitor are the followings;
Average flux density, Snu= 1.1+/- 0.1 Jy in DOY= 40- 50 (3),
Snu=1.2 +/- 0.3 Jy in DOY= 50- 60 (5),
Snu=1.1+/- 0.2 Jy in DOY= 60- 70 (7),
Snu= 1.0+/- 0.2 Jy in DOY= 70- 80 (4),
Snu= 1.1+/- 0.2 Jy in DOY= 80- 90 (7),
Snu= 1.4+/- 0.3 Jy in DOY= 90-100 (6),
Snu= 1.4+/- 0.2 Jy in DOY= 100-110 (7),
Snu= 1.6+/- 0.4 Jy in DOY= 110-120 (3),
Snu= 1.5+/- 0.4 Jy in DOY= 120-130 (7),
Snu= 1.6+/- 0.1 Jy in DOY= 130-140 (2),
Snu= 1.5+/- 0.5 Jy in DOY= 140-150 (6),
Snu= 1.2+/- 0.1 Jy in DOY= 150-160 (8),
Snu= 1.2+/- 0.3 Jy in DOY= 160-170 (2),
Snu= 1.4+/- 0.2 Jy in DOY= 170-180 (4).
Here, the numbers in parentheses are numbers of observation in the 10 days.
The errors show the scattering range (r.m.s.) of the observed flux densities.
In this observation period, Sgr A* has fluctuated gradually but
did not flare strongly.
