The search for pulsars in monitoring data obtained at the radio telescope Large Phased Array (LPA) at a frequency of 111 MHz was carried out. Daily round-the-clock observations were carried out for about 3,000 days. The duration of the observation session for each direction in the sky was 3.5 minutes per day. The search for pulsars was carried out using power spectra. To search for weak pulsars, power spectra were summed up. The expected increase in sensitivity was 35-40 times compared to observations in one session. In a blind search, 330 pulsars with regular radiation were detected, with periods (P) from 0.0333 to 3.7455 s and dispersion measures (DM) up to 249 pc/cm3. 39 pulsars turned out to be new. Average profiles were obtained for 6 pulsars. The DM for 7 pulsars previously detected on the LPA have been clarified.

In this article the title was incorrectly given as ‘‘The Method of Periodic Principal Components for the Dynamic Spectrum of Radio Pulsars and Faraday Rotation of Nine Pulse Components of PSR B0329#’’ but it should have been ‘‘The Method of Periodic Principal Components for the Dynamic Spectrum of Radio Pulsars and Faraday Rotation of Nine Pulse Components of PSR B0329+54’’.

A multichannel signal recording system (MSRS) developed for the 128-beam LPA radio telescope of PRAO ASC LPI is described. The signals coming from the radio telescope are RF signals in the frequency range of 0–115 MHz with a 2.5-MHz-wide telescope operating band located in the range of 109.0–111.5 MHz. Digitization of each signal is carried out by direct sampling at a frequency of 230 MHz with further fully digital signal processing. Processing includes transfer of the operating band towards the low-frequency region, suppression of the signal outside the operating band, and division of the useful signal into 512 spectral channels using a complex Fourier processor. All processing is performed on the basis of field-programmable gate arrays located on base modules that were specially developed by PRAO and placed in slots of industrial computers. The spectrum sequences are then transferred to the computer RAM for the recording program and then are written in a required format on a hard disk. The use of the combined hardware and software processing has made it possible to develop a compact, reliable, and inexpensive recording system. The MSRS created specifically for the LPA radio telescope is unique.

ABSTRACT We report a study of the transitional intervals between pulsar B0943+10’s two primary Q and B emission modes using Arecibo 327-MHz observations. The goal of this study was to detect signs of a ‘transitional’ mode at 327 MHz, discovered recently at lower frequencies. We have found subpulse drift and profile form patterns at 327 MHz similar to those identified at lower frequencies in the Q-to-B mode transition process. Pulse fading during about 15 stellar rotations preceding the appearance of subpulse drift was observed as well. Another part of the work is devoted to a detailed study of the pulse polarization variations in the main modes. A complex behaviour of the linear polarization percentage (LPP) of the dominant first component of the average profile with B-mode age has been found: during the first 4 h, the LPP continuously increases from 5 to 40 per cent, and over the next 1.5 h gradually decreases down to 30 per cent until the subsequent onset of the Q mode. In contrast, the LPP of the second component does not change over the B-mode lifetime, remaining at the level of 22 per cent. A non-instantaneous decrease in the LPP was detected at Q-mode onset. No systematic change of the LPP of the averaged Q-mode pulses over several hours of age was found. The results are discussed within the framework of the core–cone beam model and orthogonal polarization modes.

At the LPA LPI radio telescope, a search was conducted for pulse signals in a specific area with declinations +52°δ+55°. The processing involved ten months of observations recorded in six frequency channels, each with a channel width of 415 kHz and a total bandwidth of 2.5 MHz. The analysis of the data revealed 22 000 events, exhibiting a pronounced dispersion delay of signals over the frequency channels, which are indicative of pulsar pulses. These pulses were found to belong to four known pulsars and two new rotating radio transients (RRAT). Additional pulse search was carried out in 32-channel data with a channel width of 78 kHz. This led to the discovery of 8 pulses for the transient J0249+52 and 7 pulses for the transient J0744+55. No periodic emission of transients was detected. The analysis of the observations indicates a high probability that the identified RRATs are pulsars with nullings, where the fraction of nullings is greater than 99.9%.

A search for pulse signals was carried out in a new sky area included in the monitoring program for the search for pulsars and transients. Processing of several months data recorded in six frequency channels with a total bandwidth of 2.5 MHz showed that, on average, 4 pulses per hour are observed in each of the 24 connected stationary beams. Of these pulses, 18.3% are similar to those of pulsars. They are visible in one or two neighboring beams and have a pronounced dispersion shift, that is, they are recorded first at a high and then at a low frequency, which indicates the possible passage of the signal through the interstellar medium. Almost 68% of such detected pulses belong to six known pulsars with dispersion measures from 9 to 141 pc/cm(3), and almost all of the remaining pulses are either noise of an unknown nature or artifacts of the proposed pulse separation technique. An additional study of the selected array of 3650 obvious pulsar pulses revealed 13 pulses belonging to four rotating radio transients (RRATs). Their dispersion measures are in the range of 17-51 pc/cm(3). A search for regular (periodic) RRAT emission was carried out using power spectra summed over 121 days. Periodic radiation was not detected, but for two RRATs, upper estimates of the periods were obtained from measurements of the time intervals between pulses. The upper estimates of the integrated flux density of the detected RRATs are in the range 2-4 mJy at the frequency 111 MHz.

Pulses from 16 previously known rotating radio transients (RRAT) have been searched at the 110 MHz daily monitor program for 4 to 5.5 years by using the Large-Phased-Array (LPA) at Pushchino. The total number of pulses detected in such a long observation interval is only 90 pulses for RRAT J0640+07 or is as high as 10,751 pulses for RRAT J0302+22. The number and amplitude of pulses varies at a time-scales from six to twenty months for RRATs J1336+33, J1404+11, J1848+15, J2051+12, J2105+22, and the pulse number can increase by one or two orders of magnitude in active phases. The long-term trends are found for RRATs J0139+33 and J0302+22, showing a 2-3 times increase in detected pulse number over 1,959 days. Some RRATs show the annual variations on both pulse number and pulse amplitude. It is hard to explain all these variation time scales by refractive scintillation on the interstellar medium. The annual and semi-annual variations are likely caused by scintillations of the inhomogeneous interplanetary plasma. Our data show that the number of observational sessions with no pulse detection over the threshold decreases exponentially with the length of pulse silence.

ABSTRACT We report the result of measurements of a gradual shift of the integrated pulses towards later spin phase of the anomalous pulsar B0943+10 at high radio frequencies. We have used observations from the Arecibo Observatory and the GMRT at 327 and 325 MHz correspondingly. For the measurements, we have proposed a special method for calculating the correct positions of the partially merged two components of the pulse profile shape with significant temporal changes in their amplitude ratio. The exponential change in the pulse phase with an amplitude of 4 ms and characteristic time of about 1 h has been found. Comparison of our measurements at 325 and 327 MHz with those at the lower frequencies of 25–80, 62 and 112 MHz have shown that the character of the process does not depend on frequency across a wide frequency range. The result is very important for constraining the nature of the delay. It supports the assumption that the process results from changes in the vacuum gap near the surface of the pulsar. The further correlation between changes in the pulse phase and its intensity is discussed.

In observations of 2020 performed at the Large Phased Array radio telescope of the Lebedev Physical Institute, two new rotating transients were detected. Dispersion measures of the detected transients are DM = 21 and 35 pc/cm3, pulse half-widths are We = 18 and 35 ms for J1550+09 and J2047+13, respectively. The RRAT J2047+13 period was upper estimated as Р = 2.925. The study shows the existence occurrence of rotating transients whose pulses appear more rarely than one pulse per 10 hours of observations.

A survey of the northern hemisphere at the frequency 111 MHz is carried out. The total accumulation time for each point of the survey area was at least one hour. When searching for dispersed pulses, we detected 75 sources of pulsed radiation. More than 80% of these sources are known pulsars seen in the antenna side lobes. In twelve known pulsars, from one to several hundred pulses were detected. In four pulsars (J0157+6212, J1910+5655, J2337+6151, and J2354+6155), the narrowness of the strongest pulses and the ratio of peak flux densities in the strongest pulses and in the middle profile indicate that they may be pulsars with giant pulses. We detected one new rotating radio transient (RRAT) J0812+8626 with the dispersion measure $$DM = 40.25$$ pc/cm3.

The radio recombination lines (RRLs) of hydrogen, helium (H, He) and carbon (C) have been observed at several positions of the HII region Orion A with the RT-22 radio telescope (Pushchino) at 8 and 13 mm. Information about the ionization structure of the HII region has been obtained. The behavior of y+ = n(He+)/n(H+) over the nebula and model calculations suggest that the effective temperature (Teff) of the star θ1 C Ori is in the range 35 000–37 500 K, corresponding to a spectral type ≈O6.5 V, which is important for the calibration of hot O-B stars. The electron temperatures (Te) of this HII region have been measured by taking into account the departures from local thermodynamic equilibrium (LTE); their distribution over the nebula up to distances of 300 arcsec from the center has been derived. The inferred temperatures are in the range 6600–8400 K, strictly decreasing in the eastward directionwith distance from the center, also tend to drop toward the periphery in the southward and westward directions. The turbulent velocities (Vt) of the ionized gas and their distribution over the nebula have been determined. The values of Vt inferred from H RRLs are in the range 9–13 km s−1.

Purpose: The goal of the work is to develop a workable technique for fast processing of large arrays of radio astronomy data to search for responses to extragalactic transient events, which a priori should have large dispersion (DM ~ 100÷2000 pc · cm-3). Records of 20-day continuous observations of the sky sphere circumpolar zone with an area of about 8 sq deg and separate files with repeating fast radio burst FRB 121102 were used as a test sample of the technique. Design/methodology/approach: The BSA (Big Scanning Antenna) LPI radio telescope has a multi-beam diagram and is capable of recording daily in the frequency range of 109–111.5 MHz in 96 beams in the declination range from – 8° to +42°. The number of frequency bands varies within 6 to 32 for the time constant varying within 0.1 to 0.0125 s, respectively. In the mode of recording 32 frequency bands with the time constant 0.0125 s, 3.4 GB of data are recorded every hour, 87 GB – daily, and 32 TB – per year. To end of August 2018, about 120 TB of data have been accumulated. Processing this amount of data for a number of scientific problems urgently requires the use of high-performance computing technologies. Findings: The paper proposes two ways to process data: using graphics processors (CPU+GPU, calculation in the C/C++ programming language using OpenCL) and using cluster computing (by using the message passing interface MPI on multiprocessor nodes). To refine the methodology, we use both the processing of pulsar data (using graphic accelerators allows us to increase the processing speed by 2–3 orders of magnitude) and search for responses to extragalactic transient events, which a priori should have large dispersion delays. Examples of such events include fast radio bursts (FRB), responses to gamma radio bursts (GRB) and, finally, possible responses to gravitational events recorded by the LIGO detectors. After processing the polar zone, 697 candidates for pulsed events with high dispersion measures were detected. About half of them is caused by man-made interference, the rest being caused both by the usual interplanetary scintillations of radio sources, and also by the possible soughtfor FRBs. It is still difficult to separate these two classes of events. Processing the data observed in the FRB 121102 zone also indicates the presence of event candidates. The results require more thorough analysis. Сonclusions: After finalizing the high-performance computing methodology, it will allow us to process data observed with the BSA LPI multipath diagram immediately after they are recorded.

Results of 111-MHz monitoring observations carried out on the Big Scanning Antenna of the Pushchino Radio Astronomy Observatory during September 1–28, 2015 are presented. Fifty-four pulsating sources were detected at declinations −9° < δ < 42°. Forty-seven of these are known pulsars, five are new sources, and two are previously discovered transients. Estimates of the peak flux densities and dispersion measures are presented for all these sources.