Progress Report of the NICT VLBI Monitoring Observations of Sgr A* at 2 GHz and 8 GHz
ATel #5467; S. Takekawa, T. Oka (Keio Univ.), M. Sekido (NICT)
on 13 Oct 2013; 19:48 UT
Credential Certification: Tomoharu Oka (tomo.sarusaru@icloud.com)
Subjects: Radio, AGN, Black Hole, Transient
We report the current status of our Sgr A* monitorings. Since mid-February 2013, we have been conducting flux monitoring observations of Sgr A* at 2 GHz and 8 GHz using the NICT Kashima-Koganei VLBI system (ATel #5024). This VLBI system consists of two 11-m diameter antennas which are separated by a distance of 109.1 km. The spatial resolutions are 250 mas and 70 mas at 2 GHz and 8 GHz, respectively. Until 22 September 2013, we have obtained Sgr A* fluxes for 39 days in total, about five hours (EL > 15 degrees) each day. Four quasars (NRAO 530, PKS 1921-293, PKS 1622-253, PKS 1622-297) have been also observed as flux calibrators. In 2 GHz, Sgr A* has not been detected with our system. The 8 GHz flux density has been very stable at 0.81+/â 0.07 Jy (preliminary), without any flux variation nor flare activity. We will continue these monitorings until at least May 2014.
