Simultaneous time monitoring observations of H2O 616 − 523, SiO J = 1–0, 2–1, 3–2, and 29SiO v = 0, J = 1–0 lines are carried out in the direction of the Mira variable star TX Cam with the Korean VLBI Network single dish radio telescopes. For the first time, the H2O maser emission from TX Cam is detected near the stellar velocity at five epochs from April 10, 2013 (Ø = 3.13) to June 4, 2014 (Ø = 3.89) including minimum optical phases. The intensities of H2O masers are very weak compared to SiO masers. The variation of peak antenna temperature ratios among SiO v = 1, J = 1–0, J = 2–1, and J = 3–2 masers is investigated according to their phases. The shift of peak velocities of H2O and SiO masers with respect to the stellar velocity is also investigated according to observed optical phases. The H2O maser emission occurs around the stellar velocity during our monitoring interval. On the other hand, the peak velocities of SiO masers show a spread compared to the stellar velocity. The peak velocities of SiO J = 2–1, and J = 3–2 masers show a smaller spread with respect to the stellar velocity than those of SiO J = 1–0 masers. These simultaneous observations of multi-frequencies will provide a good constraint for maser pumping models and a good probe for investigating the stellar atmosphere and envelope according to their different excitation conditions.

We report the development of solar flux receivers operating at 2.8 GHz to monitor solar radio activity. Radio waves from the sun are amplified, filtered, and then transmitted to a power meter sensor without frequency down-conversion. To measure solar flux, a calibration scheme is designed with a noise source, an ambient load, and a hot load at 100℃. The receiver is attached to a 1.8 m parabolic antenna in Icheon, owned by National Radio Research Agency, and observation is being conducted during day time on a daily basis. We compare the solar fluxes measured for last seven months with solar fluxes obtained by DRAO in Penticton, Canada, and by the Hiraiso solar observatory in Japan, and finally establish equations to convert observed flux to the so-called Penticton flux with an accuracy better than 3.2 sfu.