Conjugates of isatin and hydrazones based on (+)-camphor and (–)-fenchone were synthesized for the first time. The physicochemical properties of the synthesized compounds have been studied, and for the hydrazone product of fenchone and isatin X-ray diffraction data have been obtained. Molecular modeling of the possible interaction of new compounds with the active site of the basic protease 3CLpro of the SARS-CoV-2 virus was carried out, and the properties of isatin-terpene compounds as inhibitors of the 3CLpro protease were studied. It was found that the new conjugates do not exhibit inhibitory properties against 3CLpro, which makes it possible to clarify the direction of further chemical modifications of monoterpenoid derivatives in order to obtain molecules with antiviral properties.

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.

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%.

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.

We have developed a model for the time delay of pulse arrival between stations on the Moon and Earth. Comparison of the lunar and terrestrial time scales is proposed to be carried out by comparing the arrival time moments of giant pulses from pulsars. A method for such a comparison has been developed based on the cross-correlation analysis of the received pulses. Using the example of giant pulses from the pulsar PSR 0531+21, we showed that the error of comparing scales in the case of a high signal-to-noise ratio reaches a sub-discrete level and, thus, is determined by the reception band of the recording equipment.

The paper considers the principles of space navigation using pulsars observed in the radio range. The requirements for receiving equipment are outlined, a recommended pulsar list is given, and an algorithm for determining the position of a spacecraft in barycentric coordinates and calculating corrections to the onboard time scale is described.

A pulsar time scale is considered, including possibilities for its realization and possible applications to fundamental problems in astronomy and physics.

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.

A method for searching for new periodic radio sources is described. The method is based on the spectral analysis of data from daily monitoring of the sky on the Large Phased Antenna (LPA) of the Pushchino Radio Astronomy Observatory at 111 MHz in a 2.5-MHz band. The 96-beam directivity pattern of the LPA is used. The signal is received in six 0.42-MHz frequency channels with a sampling rate of 0.1 s. The duration of the processed survey is four months. The particulars of detecting periodic sources with the LPA are considered. In total, 16 such radio sources have been detected, for which equatorial and Galactic coordinates, periods, and dispersion measures are given.

Purpose: One of the most interesting goals for astronomers are multi-range observations of space objects – not only in different spectral ranges, but also using other sources of information, for example, studies of objects emitting gravitational waves. Design/methodology/approach: The BSA LPI (Big Scanning Antenna of Lebedev Physical Institute) radio telescope has a multi-beam diagram and is capable of recording daily in the frequency range 109–111.5 MHz in 96 beams in the declination range from -8° to +42° daily logs 87.5 GB of data (32 TB per year). The number of frequency bands is within 6 to 32 for the time constant from 0.1 to 0.0125 s. Findings: One of the scientific tasks in processing the data obtained is to search for responses to extragalactic transient events, which a priori should have large dispersion delays (DM ~ 100-2000 pc ·cm -³). Such events include fast radio bursts (FRB) detected so far only at frequencies of 1 GHz and higher, afterglow of nearby cosmic gamma-ray bursts (GRB), in the gamma and X-ray bands, and, finally, possible electromagnetic counterparts of gravitational-wave events recorded in the LIGO-Virgo experiments. The last ones are taken in this paper as a basis for perfection of the technique of searching the like events from the BSA radio data. We provide a brief description of the methodology for finding and estimating the upper limits of possible transient radio sources accompanying the gravitational wave events GW150914, GW151226, LVT151012, and GW170104 recorded by the LIGO detectors. Сonclusions: It is established that nothing brighter than 50000 Jy in the northern hemisphere of the sky at 110 MHz was not observed at the moment of gravitational events. The estimates of energy release in the long-wave radio range are also made: the energy of the low-frequency range is ≤ 1044 erg, while the ratio of the low-frequency range energy to the energy of the gravitational event is ≤10-10.

The first results of a search for pulsars using the Large Phased Array of the Lebedev Physical Institute at 111 MHz for right ascensions 0h-24h and declinations 21°-42° are reported. Data with a time resolution of 100 ms in six frequency channels within a 2.5-MHz frequency band have been processed. Thirty-four pulsars have been detected, of which seventeen were observed on this telescope earlier; ten known pulsars had not been observed earlier. Seven new pulsars have been discovered.