Long-Term and Highly Frequent Monitor of 6.7 GHz Methanol Masers to Statistically Research Periodic Flux Variations Around High-Mass Protostars Using the Hitachi 32-M

Abstract

AbstractWe initiated a long-term and highly frequent monitoring project toward 442 methanol masers at 6.7 GHz (Dec >−30 deg) using the Hitachi 32-m radio telescope in December 2012. The observations have been carried out daily, monitoring a spectrum of each source with intervals of 9–10 days. In September 2015, the number of the target sources and intervals were redesigned into 143 and 4–5 days, respectively. This monitoring provides us complete information on how many sources show periodic flux variations …