Search

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., Comment: published in MNRAS, 13 pages, 4 figures, 4 tables, 4 appendixes

A search for pulsed radiation at a frequency of 111 MHz in the direction of 116 RRAT candidates was carried out. For the search, archival data obtained on a meridian 128-beam radio telescope, a Large Phased Array (LPA), was used. For each candidate, about six days of observations were accumulated over an interval of eight years. Eleven new RRATs have been discovered. It was possible to estimate periods for six of them, and to construct average profiles for four of them. Some of the candidates turned out to be known pulsars observed in the side lobes of the radio telescope and interference. For the part of the candidates could not find pulses with a signal-to-noise ratio of more than seven, and their nature remains unknown., Comment: published in Astronomy Letters (October 2023), translated by Yandex translator with correction of scientific lexis, 5 pages, 3 figures, 1 table

The drift periods P2 and P3 were searched for using the summed power spectra of 41 pulsars observed at declinations from -9o to +42o. The power spectra of pulses with a given period, pulse width and drift behavior have been simulated, the applicability of such a method for estimating drift parameters is shown. For most pulsars, the distribution of harmonic amplitudes in the power spectra corresponds to the expected distribution for these pulsars without drift. At the same time, it was found that for a number of sources, the summed power spectra accumulated over a long period of time give the same drift parameters as those determined by other methods. For 11 pulsars we have defined or redefined the drift period P2. For 8 sources the drift period P3 has been determined or redefined. The drift direction of subpulses was redefined for them., Comment: published in MNRAS, 10 pages, 12 figures, 1 table, 1 appendix

The effect of interplanetary plasma on pulsed pulsar radiation passing through is considered. The pulses of two rotating radio transients (J0609+16, J1132+25) and a pulsar (B0320+39) detected on the Large Phased Array (Pushchino observatory) were analyzed. It is shown that in observations at the frequency of 111 MHz, on elongations of 20o-40o, both an increase and a decrease in the number of received pulses are observed. The change in the number of pulses is explained by the distortion of the energy distribution of pulses due to interplanetary scintillation. These changes in the number of observed pulses are in qualitative agreement with the expected dependence of the scintillation index on the observed sources elongation. Analytical expressions are obtained that allow estimating the effective modulation index from observations of individual pulses for the power distribution of pulses by energy., Comment: accepted to MNRAS, 5 pages, 3 figures

The search for rotating radio transients (RRAT) at declination from -9o to +42o was carried out in the semi-annual monitoring data obtained on the Large Phased Array (LPA) radio telescope at the frequency of 111 MHz. A neural network was used to search for candidates. 4 new RRATs were detected, having dispersion measures (DM) 5-16 pc/cm3. A comparison with an earlier RRAT search conducted using the same data shows that the neural network reduced the amount of interference by 80 times, down to 1.3% of the initial amount of interferences. The loss of real pulsar pulses does not exceed 6% of their total number., Comment: 7 pages, 2 figures, submitted to A&A

The search of pulsars in monitoring observations being carried out for 5 years using LPA LPI radio telescope was done in 96 spatial beams covering daily 17,000 square degrees. Five new pulsars were detected. Candidates into pulsars were selected in the summed power spectra. The use of a noise generator allowed to renormalize the data and to perform correct summing up of the power spectra for individual directions in the sky. Herewith, the sensitivity increased more than 20 times in comparison with individual sessions of observations. For pulsars with pulse durations greater than 100 ms at declinations +30o

The survey of northern hemisphere were made at a frequency of 111 MHz. The total accumulation time at each point of the sky was at least one hour. 75 sources of pulse emission were detected. More then 80% of these sources are known pulsars observed in the side lobes of the antenna. From one to several hundreds pulses were detected in twelve known pulsars. For four pulsars (J0157+6212, J1910+5655, J2337+6151, J2354+6155) the narrowness of the strongest pulses and the ratio of peak flux densities in the strongest pulse and in the average profile indicate that they can be pulsars with giant pulses. One new rotating radio transient (RRAT) J0812+8626 with a dispersion measure DM=40.25 pc/cm3 was detected., Comment: Published in Astronomy Reports and translated from russian version of paper by Yandex translator with correction scientific lexis. 6 page, 4 figures, 1 table

The search for radio emission from the gamma pulsar J0357+3205 in the meter wavelength range was carried out. Periodic emission was found in one of the 1,700 observation sessions. The average pulsar profile is single-component with a half-width of 20-25 ms. Estimation of the pulsar flux density is 14 mJy., Comment: Published in Bulletin of Lebedev Physics Institute and translated from russian by Yandex translator with correction scientific lexis. 3 pages, 2 figures

The search for pulsar (periodic) emission of five gamma-ray pulsars was carried out using the summed power spectra and the summed periodograms. No harmonics corresponding to the known pulsar periods were found. The upper estimations of the integral flux density of the pulsars J0357+3205 (<0.5 mJy), J0554+3107 (<0.5 mJy), J1958+2846 (<0.5 mJy), J2021+4026 (<0.4 mJy), and J2055+2539 (<0.55 mJy) is obtained., Comment: Published in Astronomy Reports and translated from russian version of paper by Yandex translator with correction scientific lexis. 6 page, 1 figure, 1 table

The analysis of individual pulses of four rotating radio transients (RRATs), previously discovered in a monitoring survey running for 5.5 years at the frequency of 111 MHz, is presented. At a time interval equivalent to five days of continuous observations for each RRAT, 90, 389, 206, and 157 pulses were detected in J0640+07, J1005+30, J1132+25, and J1336+33, respectively. The investigated RRATs have a different distribution of the pulses amplitude. For J0640+07 and J1132+25, the distribution is described by a single exponent over the entire range of flux densities. For J1005+30 and J1336+33, it is a lognormal function with a power law tail. For J0640+07 and J1005+30, we have detected pulses with a signal-to-noise (S/N) ratio of few hundreds. For J1132+25 and J1336+33, the S/N of the strongest pulses reaches several tens. These RRATs show strong changing of character of emission. When strengths of pulse amplitudes significantly changed, we see long intervals of absence of emission or its strong attenuation. The analysis carried out in this work shows that it is possible that all the studied RRATs are, apparently, pulsars with giant pulses., Comment: 9 pages, 5 figures

The search for pulsars in a sample of pulsar candidates found based on a multi-year survey conducted with low (6 channels; sampling 0.1s) time-frequency resolution on declinations -9^o < \delta < +42^o was carried out. A Large Phased Array (LPA) transit telescope operating at 111 MHz in the 2.5 MHz band was used. Search, analysis and evidence of pulsar detection were carried out using a visualization program of summed up power spectra obtained from the survey data with high 32 channels; sampling 12.5ms) time-frequency resolution. 11 new pulsars with periods P0 = 0.41-3.75 s and dispersion measure DM=15-154 pc/cm^3 have been discovered. In total, in the survey with a low time-frequency resolution for the period 2016-2021 in a blind search, 208 pulsars were found, of them 42 new and 166 known pulsars. It is shown that in the search on the data with high time-frequency resolution accumulated over a time interval of 7 years, pulsars with a flux density of 0.1 - 0.2 mJy at the frequency of 111 MHz can be detected. When searching for pulsars with regular (periodic) emission at declinations +21^o < \delta < +42^o, all pulsars located outside the galactic plane, having P0 \ge 0.5 s, DM \le 100 pc/cm^3 and the flux density S \ge 0.5 mJy, can be detected, Comment: 13 pages, 7 figures, submitted to MNRAS

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., Comment: 13 pages, 7 figures, submitted to MNRAS

Since the discovery of pulsars, dozens of surveys have already been conducted with their searches. In the course of surveys in the sky, areas from thousands to tens of thousands of square degrees are explored. Despite repeated observations of the same areas, new pulsars are constantly being discovered. We present Pushchino Multibeam Pulsar Search (PUMPS), having a sensitivity that is an order of magnitude higher than the sensitivity of all previously made surveys on pulsar search. In PUMPS daily round-the-clock observations are carried out of the area located on declinations $-9^o < \delta < +42^o$. The survey is carried out on 96 beams of a Large Phased Array (LPA) at a frequency of 111 MHz. During the observation period of August 2014 - August 2022, the survey was repeated approximately 3,000 times. The expected sensitivity in the survey reaches up to 0.1 mJy. The paper considers some tasks that can be solved when processing the received data., Comment: Proceedings of Science (PoS), submitted, 8 pages, 3 figures

The search for compact components of strong ($S_{int} \ge 5$ Jy at 102.5 MHz) discrete radio sources from the Pushchino catalogue was carried out using the method of interplanetary scintillation. A total of 3620 sources were examined, and 812 of them were found to compact (scintillating) components. Estimates of fluctuations of the flux density of these compact components were derived from the scintillation index ($m_{max}$) corresponding to an elongation of $25^o$. The angular size and compactness of 178 sources with compact components were estimated. Scintillation indices of sources corresponding to the compact component ($m_{max}$) and flux densities of compact components were determined. It was demonstrated that slow variations of the spatial distribution of interplanetary plasma, which are related to the 11-year cycle of solar activity, may exert a systematic influence on the estimates of angular sizes of sources. Coefficients compensating the deviation from the spherical symmetry of solar wind in the estimates of angular sizes were found using the coefficient of asymmetry of the statistical distribution of intensity fluctuations. The study of correlations between the parameters of sources in the sample revealed that the maximum value of the scintillation index decreases as the integrated flux increases, while the angular size has no marked dependence on the integrated flux., Comment: published in Astronomy Report, translated by Yandex translator with correction of scientific lexis, 16 pages, 6 figures, 3 table, appendix

Pulsars with periods more than 0.4 seconds in the declination range -9o < decj < 42o and in the right ascension range 0h < r.a.< 24h were searched in parallel with the program of interplanetary scintillations monitoring of a large number of sources with the radiotelescope LPA LPI. Four-year observations carried out at the central frequency 110.25 MHz in the band 2.5 MHz and in six frequency channels with the time resolution 100 ms were used for the search. Initial detections of candidates for pulsars were based on the Fourier power spectra averaged over the whole observations period. The candidates for pulsars were checked in more details from observations analysis with higher time-frequency resolution: 32 frequency channels with time resolution of 12.5 ms. 18 new pulsars was discovered, their main characteristics are presented., Comment: published in Astronomy Report, translated by Yandex translator with correction of scientific lexis, 9 pages, 5 figures, 1 table

The search for pulsar (periodic) emission of five gamma-ray pulsars was carried out using the summed power spectra and the summed periodograms. No harmonics corresponding to the known pulsar periods were found. The upper estimations of the integral flux density of the pulsars J0357+3205 (<0.5 mJy), J0554+3107 (<0.5 mJy), J1958+2846 (<0.5 mJy), J2021+4026 (<0.4 mJy), and J2055+2539 (<0.55 mJy) is obtained., Comment: Published in Astronomy Reports and translated from russian version of paper by Yandex translator with correction scientific lexis. 6 page, 1 figure, 1 table

The survey of northern hemisphere were made at a frequency of 111 MHz. The total accumulation time at each point of the sky was at least one hour. 75 sources of pulse emission were detected. More then 80% of these sources are known pulsars observed in the side lobes of the antenna. From one to several hundreds pulses were detected in twelve known pulsars. For four pulsars (J0157+6212, J1910+5655, J2337+6151, J2354+6155) the narrowness of the strongest pulses and the ratio of peak flux densities in the strongest pulse and in the average profile indicate that they can be pulsars with giant pulses. One new rotating radio transient (RRAT) J0812+8626 with a dispersion measure DM=40.25 pc/cm3 was detected., Comment: Published in Astronomy Reports and translated from russian version of paper by Yandex translator with correction scientific lexis. 6 page, 4 figures, 1 table

The search of pulsars in monitoring observations being carried out for 5 years using LPA LPI radio telescope was done in 96 spatial beams covering daily 17,000 square degrees. Five new pulsars were detected. Candidates into pulsars were selected in the summed power spectra. The use of a noise generator allowed to renormalize the data and to perform correct summing up of the power spectra for individual directions in the sky. Herewith, the sensitivity increased more than 20 times in comparison with individual sessions of observations. For pulsars with pulse durations greater than 100 ms at declinations +30o

The search for rotating radio transients (RRAT) at declination from -9o to +42o was carried out in the semi-annual monitoring data obtained on the Large Phased Array (LPA) radio telescope at the frequency of 111 MHz. A neural network was used to search for candidates. 4 new RRATs were detected, having dispersion measures (DM) 5-16 pc/cm3. A comparison with an earlier RRAT search conducted using the same data shows that the neural network reduced the amount of interference by 80 times, down to 1.3% of the initial amount of interferences. The loss of real pulsar pulses does not exceed 6% of their total number., Comment: 7 pages, 2 figures, submitted to A&A

The search for radio emission from the gamma pulsar J0357+3205 in the meter wavelength range was carried out. Periodic emission was found in one of the 1,700 observation sessions. The average pulsar profile is single-component with a half-width of 20-25 ms. Estimation of the pulsar flux density is 14 mJy., Comment: Published in Bulletin of Lebedev Physics Institute and translated from russian by Yandex translator with correction scientific lexis. 3 pages, 2 figures

The analysis of individual pulses of four rotating radio transients (RRATs), previously discovered in a monitoring survey running for 5.5 years at the frequency of 111 MHz, is presented. At a time interval equivalent to five days of continuous observations for each RRAT, 90, 389, 206, and 157 pulses were detected in J0640+07, J1005+30, J1132+25, and J1336+33, respectively. The investigated RRATs have a different distribution of the pulses amplitude. For J0640+07 and J1132+25, the distribution is described by a single exponent over the entire range of flux densities. For J1005+30 and J1336+33, it is a lognormal function with a power law tail. For J0640+07 and J1005+30, we have detected pulses with a signal-to-noise (S/N) ratio of few hundreds. For J1132+25 and J1336+33, the S/N of the strongest pulses reaches several tens. These RRATs show strong changing of character of emission. When strengths of pulse amplitudes significantly changed, we see long intervals of absence of emission or its strong attenuation. The analysis carried out in this work shows that it is possible that all the studied RRATs are, apparently, pulsars with giant pulses., Comment: 9 pages, 5 figures

The search for pulsars in a sample of pulsar candidates found based on a multi-year survey conducted with low (6 channels; sampling 0.1s) time-frequency resolution on declinations -9^o < \delta < +42^o was carried out. A Large Phased Array (LPA) transit telescope operating at 111 MHz in the 2.5 MHz band was used. Search, analysis and evidence of pulsar detection were carried out using a visualization program of summed up power spectra obtained from the survey data with high 32 channels; sampling 12.5ms) time-frequency resolution. 11 new pulsars with periods P0 = 0.41-3.75 s and dispersion measure DM=15-154 pc/cm^3 have been discovered. In total, in the survey with a low time-frequency resolution for the period 2016-2021 in a blind search, 208 pulsars were found, of them 42 new and 166 known pulsars. It is shown that in the search on the data with high time-frequency resolution accumulated over a time interval of 7 years, pulsars with a flux density of 0.1 - 0.2 mJy at the frequency of 111 MHz can be detected. When searching for pulsars with regular (periodic) emission at declinations +21^o < \delta < +42^o, all pulsars located outside the galactic plane, having P0 \ge 0.5 s, DM \le 100 pc/cm^3 and the flux density S \ge 0.5 mJy, can be detected, Comment: 13 pages, 7 figures, submitted to MNRAS

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., Comment: 13 pages, 7 figures, submitted to MNRAS

The Pushchino Observatory of ASC LPI have been developing in some last years database of some astronomical catalogs (Radio Astronomy Data Center - RADC, look on http://astro.prao.ru/db/ and http://observations.prao.ru/). In the database have the most commonly used by radio astronomers data: survey catalogs of radio sources at different radio frequencies (as well as in other spectral bands), catalogs of the major sky objects studied in astronomy etc.

From 2012 on radio telescope BSA FIAN multi beams diagram was started. It capable at July 2014 daily observing by 96 beams in declination -8 .. 42 degrees in the frequency band 109-111.5 MHz. The number of frequency bands are from 6 to 32, the time constant are from 0.1 to 0.0125 sec. In receiving mode with 32 band (plus one common band) with a time constant of 12.5 ms (80 times per second) respectively produced 33x96x80 four byte real and so daily we produced 87.5 Gbt (yearly to 32 Tbt). These data are enormous opportunities for both short and long-term monitoring of various classes of radio sources (including radio transients) and for space weather and the Earth's ionosphere monitoring, for search for different classes of radio sources, etc. The base aims of our work are: a) to obtain new scientific data on different classes of discrete radio sources, the construction of physical models and their evolution - obtained on the basis of the clock continuous digital sky radio monitoring at frequency 109- 111.5 MHz and cross-analysis of data from third-party reviews on other frequencies; c) launch the streaming data on various types of highperformance computing systems, including to create a public system of distributed computing for thousands of users on the basis of BOINC technology. The BOINC client for astronomical data from the monitoring survey of the big part of entire sky almost have not analogies. We have some first science results (new pulsars, and some new type of radiosources).

From 2012 on radio telescope BSA FIAN multi beams diagram was started. It capable at July 2014 daily observing by 96 beams in declination -8 .. 42 degrees in the frequency band 109-111.5 MHz. The number of frequency bands are from 6 to 32, the time constant are from 0.1 to 0.0125 sec. In receiving mode with 32 band (plus one common band) with a time constant of 12.5 ms (80 times per second) respectively produced 33x96x80 four byte real and so daily we produced 87.5 Gbt (yearly to 32 Tbt). These data are enormous opportunities for both short and long-term monitoring of various classes of radio sources (including radio transients) and for space weather and the Earth's ionosphere monitoring, for search for different classes of radio sources, etc.

Buffer data center was created in the territory of the Pushchino Radio Astronomy Observatory three years ago. The necessity of its creation was caused by the high requirements to the speed and quality of the transmission large amounts of scientific and telemetry data received by tracking station RT-22 from the space radio telescope of the international project “Radioastron”. The transfer of this data is carried out over a long distance over100 kmfrom the Pushchino toMoscowcenter of processing and storage ASC FIAN. And now we use the data center as a center of local network of the Observatory.

Now a day the task of comparative analysis of sample sources from different astronomical catalogs is becoming very topical for astronomers. It is useful both for the same spectral range data and for their cross-analysis for different spectral ranges. It is also important, that the real data from astronomical instruments is placed on-line. For the above purposes we are developing a website for the PRAO ASC LPI (www.prao.ru) and, based upon it, the Radio As­tronomy Data Center (RADC). The RADC is a system for storage and processing of radio astronomical data. Here you can find a collection of tools for preparing radio astronomical observations, which includes a base set of main astronomical catalogues useful to radio astronomers, as well as a database of observation results from the Observatory.

1. Factors which determine the possibility of amino-nitrile cleavage of hydrazones on electrochemical reduction (ECR) include the basicity of the anionic product formed in the course of the ECR and the mobility of the aldehyde hydrogen which depends on the character of the electron polarization of the hydrazone fragment and the polarity of the N-N bond. 2. The primary action in amino-nitrile cleavage under conditions of ECR is the deprotonation of the azomethine fragment in the unreduced molecule by electrochemically generated strong base (anion or dianion). © 1988 Plenum Publishing Corporation.

1. Factors which determine the possibility of amino-nitrile cleavage of hydrazones on electrochemical reduction (ECR) include the basicity of the anionic product formed in the course of the ECR and the mobility of the aldehyde hydrogen which depends on the character of the electron polarization of the hydrazone fragment and the polarity of the N-N bond. 2. The primary action in amino-nitrile cleavage under conditions of ECR is the deprotonation of the azomethine fragment in the unreduced molecule by electrochemically generated strong base (anion or dianion). © 1988 Plenum Publishing Corporation.