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The paper is devoted to the analysis of the observation results with the single-mirror radio telescope RT-22 (PRAO, LPI) in the water vapor maser line at 22 GHz in the direction of dust clumps from the ATLASGAL and Bolocam large-scale blind surveys in the millimeter continuum. The aim of this paper is to search for masers in the water vapor line in previously unexplored sources and to study the variability of known masers. Observations of 140 sources resulted in the detection of maser emission at 22 GHz in six sources, and in four sources (ATLASGAL 016.987+00.981, 017.216+00.821, 018.701–00.229, and Bolocam 081.174–00.100) masers were detected for the first time. In two sources (ATLASGAL 034.195–0.592 and Bolocam 081.174–0.1), the water vapor line masers showed significant variability during the 8-month observation and follow-up program. Comparison of RT-22 observational data with archival data from the GBT‑100 telescope (US National Radio Astronomy Observatory) showed that 9 out of 140 sources show a significant change in the radiation flux density of masers: two sources changed from the category of masers with low brightness ( Jy) to the category bright (more than 10 Jy), and in seven relatively bright earlier (more than 3 Jy) masers, no radiation was detected. Significant changes in the characteristics of the maser emission may indicate changes in the environmental conditions in which the maser emission was produced, which is of interest for further study of maser-related processes. [ABSTRACT FROM AUTHOR]

The paper presents results of calculating the RATAN-600 beam pattern (BP) and BP drift scans of point radio sources in the West Sector radio telescope operation mode at a frequency of 4.7 GHz. When calculating the BP, the properties of the radio telescope antenna system in this operation mode were taken into account: the use of a large secondary mirror, asymmetric radiation of the primary mirror, and the location of the primary feeds (feed horns) along the focal line of the secondary mirror. The shape of the calculated drift scans of sources through the BP is compared with that of the experimental drift scans of sources obtained from observations in the West Sector. The main characteristics of the drift scans are calculated and compared when the radio telescope operates with the West and North Sectors. A new method for determination of flux densities of sources passing through the BP outside its central cross-section is proposed, and its accuracy is estimated. [ABSTRACT FROM AUTHOR]

Results of a study of powerful H2O maser flares in the W51 region from observations (monitoring) in 2009–2022 with the 22-m radio telescope in the Pushchino Radio Astronomy Observatory are presented. Three powerful maser flares were detected at radial velocities of 69.7, 61.6, and 59.0 km/s with flux densities at peaks of 23.1, 29.4, and 66.1 kJy, respectively. The first and third of them are identified with the main source (W51 Main). A probable reason for their occurrence may be the superposition of two maser condensations with close radial velocities on the line of sight. A large number of flares with flux densities above 10 kJy were also detected, most of which were identified with W51 North. The mechanism for the appearance of the asymmetry of the line for the most powerful flare at a radial velocity of 59 km/s is discussed. [ABSTRACT FROM AUTHOR]