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Several multifrequency polarization studies have shown the presence of systematic Faraday Rotation gradients across the parsec-scale jets of active galactic nuclei, taken to be due to the systematic variation of the line-of-sight component of a helical magnetic (B) field across the jet. Other studies have confirmed the presence and sense of these gradients in several sources, thus providing evidence that these gradients persist over time and over large distances from the core. However, we find surprising new evidence for a reversal in the direction of the Faraday Rotation gradient across the jet of B1803+784, for which multifrequency polarization observations are available at four epochs. At our three epochs and the epoch of Zavala & Taylor, we observe transverse rotation measure (RM) gradients across the jet, consistent with the presence of a helical magnetic field wrapped around the jet. However, we also observe a 'flip' in the direction of the gradient between 2000 June and 2002 August. Although the origins of this phenomenon are not entirely clear, possibly explanations include (i) the sense of rotation of the central supermassive black hole and accretion disc has remained the same, but the dominant magnetic pole facing the Earth has changed from north to south, (ii) a change in the direction of the azimuthal B field component as a result of torsional oscillations of the jet and (iii) a change in the relative contributions to the observed RMs of the 'inner' and 'outer' helical fields in a magnetic-tower model. Although we cannot entirely rule out the possibility that the observed changes in the RM distribution are associated instead with changes in the thermal-electron distribution in the vicinity of the jet, we argue that this explanation is unlikely

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We report on NICER X-ray monitoring of the magnetar SGR 1830−0645 covering 223 days following its 2020 October outburst, as well as Chandra and radio observations. We present the most accurate spin ephemerides of the source so far: ν = 0.096008680(2) Hz, ν ̇ = − 6.2 ( 1 ) × 10 − 14 Hz s−1, and significant second and third frequency derivative terms indicative of nonnegligible timing noise. The phase-averaged 0.8–7 keV spectrum is well fit with a double-blackbody (BB) model throughout the campaign. The BB temperatures remain constant at 0.46 and 1.2 keV. The areas and flux of each component decreased by a factor of 6, initially through a steep decay trend lasting about 46 days, followed by a shallow long-term one. The pulse shape in the same energy range is initially complex, exhibiting three distinct peaks, yet with clear continuous evolution throughout the outburst toward a simpler, single-pulse shape. The rms pulsed fraction is high and increases from about 40% to 50%. We find no dependence of pulse shape or fraction on energy. These results suggest that multiple hot spots, possibly possessing temperature gradients, emerged at outburst onset and shrank as the outburst decayed. We detect 84 faint bursts with NICER, having a strong preference for occurring close to the surface emission pulse maximum—the first time this phenomenon is detected in such a large burst sample. This likely implies a very low altitude for the burst emission region and a triggering mechanism connected to the surface active zone. Finally, our radio observations at several epochs and multiple frequencies reveal no evidence of pulsed or burst-like radio emission.

This paper presents implementation of spectrometer based on off-the-shelf software defined radio (SDR) Ettus Research USRP X300 equipped with TwinRX daughterboard. Parallelized software, employing Fast Fourier Transform (FFT), is developed which allows two channel spectrum processing in real time with bandwidths up to 50[Formula: see text]MHz per channel, sample resolution of 14 bits and FFT lengths up to 32k points. Measured Allan stability time of the spectrometer is at least 750 sin laboratory environment. Software has network server-type interface that allows to conveniently integrate the spectrometer in radio telescope observation control and monitoring system with versatility of SDR allowing to implement various observation modes, for example, total power detection functionality with high frequency selectivity, which allows to carry continuum amplitude calibration in presence of near-by radio frequency interference. Presented spectrometer has been successfully integrated and used at RT-32 and RT-16 radio telescopes of Ventspils International Radio Astronomy Centre.

Governmental support and the availability of large unpopulated areas on the coasts of the Baltic countries make attractive the use of these lands for siting large wind power plants (WPP). Studies in the area of wind energy resource distribution are carried out by the IPE with collaboration with the VeU. The observations of wind speed were made using the measuring complex NRG LOGGER 9200 Symphonie. The results of long-term observations on the wind energy density fluctuations at heights of 10 to 60 m in the area on the Baltic Sea coast of Latvia are presented in the form of tables, bar charts and graphs. The wind speed distribution is analysed. The coefficients of approximating functions for two areas of different terrain types have been calculated, and extrapolation results for the distribution curves of wind speed and energy density obtained. The acoustic noise level distribution around a planned WPP has been modelled.

The article investigates the properties and potential of compressed hydrogen as one of the most promising energy carriers in order to facilitate the development of energy storage capabilities and lay down a stable foundation for the future of a sustainable energy sector. The study considers the use of hydrogen, compressed at high pressure from 50 MPa to 100 MPa, at refuelling stations to supply electric cars. The technical properties of modern hydraulic compressors used for hydrogen accumulation in high pressure buffer containers are considered. The study shows that the design of hydraulic compressors in terms of their technical characteristics optimally corresponds to the primary requirements for their use as booster compressors at refuelling stations. The authors conclude with the proposal of an enhanced design of the hydraulic compressor with the use of fluid flow counters in a control system of a hydrogen compression cycle. The proposed technical solution provides for continuous monitoring of the hydrogen compression process that increases the reliability of control system operation.

Aims. Molecular masers, including methanol and hydroxyl masers, and in particular the ones in excited rotational states (ex-OH masers), are one of the most informative tools for studying star-forming regions. So, the discovery, of new maser sources in these regions is of great importance. Many studies and surveys of ex-OH maser sources have been carried out in the southern celestial hemisphere, but only a few have been done in the northern hemisphere. The specific aim of this work is to close this gap. Methods. The star-forming regions in the northern hemisphere with known active methanol masers were observed to search for new ex-OH maser sources with the 32 m and 16 m radio telescopes of the Ventspils International Radio Astronomy Centre (VIRAC). Results. Three OH maser lines in the excited state at the 6035 MHz in three northern hemisphere star-forming regions are detected. The maser 189.030+0.783 was previously known, but we suggest this maser is a possible variable. We confirm recent detections of the ex-OH masers 85.41+0.00 and 90.92+1.49 by other authors. The magnetic field strength in the masering regions is estimated by using right circular polarization and left circular polarization pair splitting. The high-velocity resolution provides us with an estimation of a comparatively small magnetic field strength for the 189.030+0.783 and 90.92+1.49 star-forming regions.