Multi-epoch VLBI of a double maser super burst

In a rare and spectacular display, two well-known massive star forming regions, W49N and G25.65+1.05, recently underwent maser 'super burst' - their fluxes suddenly increasing above 30,000 and 18,000 Jy, respectively, reaching several orders of magnitude above their usual values. In quick-response, ToO observations with the EVN, VLBA and KaVA were obtained constituting a 4 week campaign - producing a high-cadence multi-epoch VLBI investigation of the maser emission. The combination of high-resolution, polarisation and flux monitoring during the burst provides one of the best accounts, to date, of the maser super burst phenomenon, aiding their use as astrophysical tools. These proceedings contain the preliminary results of our campaign

Recent updates on the Maser Monitoring Organisation

The Maser Monitoring Organisation (M2O) is a research community of telescope operators, astronomy researchers and maser theoreticians pursuing a joint goal of reaching a deeper understanding of maser emission and exploring its variety of uses as tracers of astrophysical events. These proceedings detail the origin, motivations and current status of the M2O, as was introduced at the 2021 EVN symposium

A Close Binary Supermassive Black Hole Model for the Galaxy 3C 273

The data from the last 60 years on the programs of long-term multi-frequency monitoring of active galactic nucleus (AGN) 3C 273 were analyzed. A model is proposed for finding the parameters of close binary systems (CBSs) from supermassive black holes (SMBHs), including a harmonic analysis of observational data series obtained in the optical and radio ranges. The purpose of this research was to show that in the absence of optical information on AGNs, only radio data can be used and the necessary information on the physical objects can be obtained. Regarding the example of the blazar 3C 273, the following parameters were obtained: the masses of the companions; their orbital characteristics, such as the speeds of movement in orbits; the reserves of the kinetic energy of the system; and others. It was found that AGN 3C 273 can be a very massive binary system at the stage of evolution close to merging. Based on the obtained parameters, the characteristics of the gravitational waves (GWs) of this system, its lifetime before the merger, and the possible observation of 3C 273 using gravitational wave detectors were considered

Polygon “Simeiz-Katsively” - changes in the average pole of the Earth and the geomagnetic field over the last century

The character of changing the trajectory of the middle of the North geographical pole of the Earth's surface over the last century is studied. The peculiarities in the changes of its coordinates are established. The epochs of the appearance of especial points are compared with the epochs of jumps in the data on the parameters of the geomagnetic field. A model of secular variations of geomagnetic declination at a point with geodetic coordinates of 90° north latitude, 0° west longitude is obtained. Coherent relationships have been established between changes in the parameters of the Earth’s middle pole and the geomagnetic field over the past century

Polygon “Simeiz-Katsively” - fluctuations in the local deformations and insolation the Earth's surface

Discovered the effects of regular solar and geodynamic fluctuations in satellite data on the insolation falling on the earth's surface at the point of the Kara-Dag for the period 1983.5 in 2005.5 years. The parameters of the seasonal component are determined. Possible reasons for the increase in the amplitude of the seasonal component are discussed

Millimeter methanol emission in the high-mass young stellar object G24.33+0.14

In 2019 September, a sudden flare of the 6.7 GHz methanol maser was observed toward the high-mass young stellar object (HMYSO) G24.33+0.14. This may represent the fourth detection of a transient mass accretion event in an HMYSO after S255IR NIRS3, NGC 6334I-MM1, and G358.93−0.03-MM1. G24.33+0.14 is unique among these sources as it clearly shows a repeating flare with an 8 yr interval. Using the Atacama Large Millimeter/submillimeter Array (ALMA), we observed the millimeter continuum and molecular lines toward G24.33+0.14 in the pre-flare phase in 2016 August (ALMA Cycle 3) and the mid-flare phase in 2019 September (ALMA Cycle 6). We identified three continuum sources in G24.33+0.14, and the brightest source, C1, which is closely associated with the 6.7 GHz maser emission, shows only a marginal increase in flux density with a flux ratio (Cycle 6$/$Cycle 3) of 1.16 ± 0.01, considering an additional absolute flux calibration uncertainty of $10\%$. We identified 26 transitions from 13 molecular species other than methanol, and they exhibit similar levels of flux differences with an average flux ratio of 1.12 ± 0.15. In contrast, eight methanol lines observed in Cycle 6 are brighter than those in Cycle 3 with an average flux ratio of 1.23 ± 0.13, and the higher excitation lines tend to show a larger flux increase. If this systematic increasing trend is real, it would suggest radiative heating close to the central HMYSO due to an accretion event which could expand the size of the emission region and/or change the excitation conditions. Given the low brightness temperatures and small flux changes, most of the methanol emission is likely to be predominantly thermal, except for the 229.759 GHz (8−1–70 E) line known as a class I methanol maser. The flux change in the millimeter continuum of G24.33+0.14 is smaller than in S255IR NIRS3 and NGC 6334I-MM1 but is comparable with that in G358.93−0.03-MM1, suggesting different amounts of accreted mass in these events

Millimeter methanol emission in the high-mass young stellar object G24.33+0.14

<jats:title>Abstract</jats:title> <jats:p>In 2019 September, a sudden flare of the 6.7???GHz methanol maser was observed toward the high-mass young stellar object (HMYSO) G24.33+0.14. This may represent the fourth detection of a transient mass accretion event in an HMYSO after S255IR??NIRS3, NGC??6334I-MM1, and G358.93???0.03-MM1. G24.33+0.14 is unique among these sources as it clearly shows a repeating flare with an 8???yr interval. Using the Atacama Large Millimeter/submillimeter Array (ALMA), we observed the millimeter continuum and molecular lines toward G24.33+0.14 in the pre-flare phase in 2016 August (ALMA Cycle??3) and the mid-flare phase in 2019 September (ALMA Cycle??6). We identified three continuum sources in G24.33+0.14, and the brightest source, C1, which is closely associated with the 6.7???GHz maser emission, shows only a marginal increase in flux density with a flux ratio (Cycle??6$/$Cycle??3) of 1.16 ?? 0.01, considering an additional absolute flux calibration uncertainty of $10\%$. We identified 26 transitions from 13 molecular species other than methanol, and they exhibit similar levels of flux differences with an average flux ratio of 1.12 ?? 0.15. In contrast, eight methanol lines observed in Cycle??6 are brighter than those in Cycle??3 with an average flux ratio of 1.23 ?? 0.13, and the higher excitation lines tend to show a larger flux increase. If this systematic increasing trend is real, it would suggest radiative heating close to the central HMYSO due to an accretion event which could expand the size of the emission region and/or change the excitation conditions. Given the low brightness temperatures and small flux changes, most of the methanol emission is likely to be predominantly thermal, except for the 229.759???GHz (8???1???70??E) line known as a class??I methanol maser. The flux change in the millimeter continuum of G24.33+0.14 is smaller than in S255IR??NIRS3 and NGC??6334I-MM1 but is comparable with that in G358.93???0.03-MM1, suggesting different amounts of accreted mass in these events.</jats:p&gt