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We present a detection of a bright burst from FRB 20201124A, which is one of the most active repeating FRBs, based on S-band observations with the 64-m radio telescope at the Usuda Deep Space Center/JAXA. This is the first FRB observed by using a Japanese facility. Our detection at 2 GHz in February 2022 is the highest frequency for this FRB and the fluence of $>$ 189 Jy ms is one of the brightest bursts from this FRB source. We place an upper limit on the spectral index $\alpha$ = -2.14 from the detection of the S band and non-detection of the X band at the same time. We compare an event rate of the detected burst with ones of the previous research, and suggest that the power-law of the luminosity function might be broken at lower fluence, and the fluences of bright FRBs distribute up to over 2 GHz with the power-law against frequency. In addition, we show the energy density of the burst detected in this work was comparable to the bright population of one-off FRBs. We propose that repeating FRBs can be as bright as one-off FRBs, and only their brightest bursts could be detected so some of repeating FRBs intrinsically might have been classified as one-off FRBs., Comment: 8 pages, 5 figures, accepted for publication in Publications of the Astronomical Society of Japan (PASJ)

We report on the multi-frequency multi-epoch radio observations of the magnetar, XTE J1810-197, which exhibited a radio outburst from December 2018 after its 10-year quiescent period. We performed quasi-simultaneous observations with VERA (22 GHz), Hitachi (6.9 GHz and 8.4 GHz), Kashima (2.3 GHz), and Iitate (0.3 GHz) radio telescopes located in Japan to trace the variability of the magnetar radio pulsations during the observing period from 13 December 2018 to 12 June 2019. The pulse width goes narrower as the observing frequency goes higher, analogous to the general profile narrowing behavior of ordinary pulsars. When assuming a simple power law in the range of 2.3 GHz and 8.7 GHz, the radio spectrum of the magnetar goes steeper with the average spectral index $ \langle \alpha \rangle \approx -0.85$ for the first four months. The wide-band radio spectra inferred from our observations and the literature suggest that XTE J1810-197 would have a double-peaked spectrum with a valley point in 22 - 150 GHz, where the first spectral peak infers a gigahertz-peaked spectrum (GPS) feature with a peak at a few GHz. The GPS and the high-frequency peak have been identified in the spectra of other radio-loud magnetars, thus they may be intrinsic features that can give a new insight to understand various emission mechanisms and surrounding environments of radio magnetars. Our study emphasizes the importance of simultaneous long-term broad-band observations toward radio-loud magnetars to capture the puzzling spectral features and establish a link to other types of neutron stars., Comment: 13 pages, 5 figures, accepted for publication in Publications of the Astronomical Society of Japan (PASJ)

Giant radio pulses (GRPs) are sporadic bursts emitted by some pulsars, lasting a few microseconds. GRPs are hundreds to thousands of times brighter than regular pulses from these sources. The only GRP-associated emission outside radio wavelengths is from the Crab Pulsar, where optical emission is enhanced by a few percent during GRPs. We observed the Crab Pulsar simultaneously at X-ray and radio wavelengths, finding enhancement of the X-ray emission by $3.8\pm0.7\%$ (a 5.4$\sigma$ detection) coinciding with GRPs. This implies that the total emitted energy from GRPs is tens to hundreds of times higher than previously known. We discuss the implications for the pulsar emission mechanism and extragalactic fast radio bursts., Comment: 63 pages, 23 figures, 7 Tables. Published in Science

The balloon-borne very long baseline interferometry (VLBI) experiment is a technical feasibility study for performing radio interferometry in the stratosphere. The flight model has been developed. A balloon-borne VLBI station will be launched to establish interferometric fringes with ground-based VLBI stations distributed over the Japanese islands at an observing frequency of approximately 20 GHz as the first step. This paper describes the system design and development of a series of observing instruments and bus systems. In addition to the advantages of avoiding the atmospheric effects of absorption and fluctuation in high frequency radio observation, the mobility of a station can improve the sampling coverage (`uv-coverage') by increasing the number of baselines by the number of ground-based counterparts for each observation day. This benefit cannot be obtained with conventional arrays that solely comprise ground-based stations. The balloon-borne VLBI can contribute to a future progress of research fields such as black holes by direct imaging., Comment: 15 pages, 6 figures, 1 table. Advances in Space Research, in press

To search for giant X-ray pulses correlated with the giant radio pulses (GRPs) from the Crab pulsar, we performed a simultaneous observation of the Crab pulsar with the X-ray satellite Hitomi in the 2 -- 300 keV band and the Kashima NICT radio observatory in the 1.4 -- 1.7 GHz band with a net exposure of about 2 ks on 25 March 2016, just before the loss of the Hitomi mission.The timing performance of the Hitomi instruments was confirmed to meet the timing requirement and about 1,000 and 100 GRPs were simultaneously observed at the main and inter-pulse phases, respectively, and we found no apparent correlation between the giant radio pulses and the X-ray emission in either the main or inter-pulse phases.All variations are within the 2 sigma fluctuations of the X-ray fluxes at the pulse peaks, and the 3 sigma upper limits of variations of main- or inter- pulse GRPs are 22\% or 80\% of the peak flux in a 0.20 phase width, respectively, in the 2 -- 300 keV band.The values become 25\% or 110\% for main or inter-pulse GRPs, respectively, when the phase width is restricted into the 0.03 phase.Among the upper limits from the Hitomi satellite, those in the 4.5-10 keV and the 70-300 keV are obtained for the first time, and those in other bands are consistent with previous reports.Numerically, the upper limits of main- and inter-pulse GRPs in the 0.20 phase width are about (2.4 and 9.3) $\times 10^{-11}$ erg cm$^{-2}$, respectively. No significant variability in pulse profiles implies that the GRPs originated from a local place within the magnetosphere and the number of photon-emitting particles temporally increases.However, the results do not statistically rule out variations correlated with the GRPs, because the possible X-ray enhancement may appear due to a $>0.02$\% brightening of the pulse-peak flux under such conditions., Comment: 18 pages, 7 figure, 6 tables, accepted for publication in PASJ

We present the results of the simultaneous observation of the giant radio pulses (GRPs) from the Crab pulsar at 0.3, 1.6, 2.2, 6.7, and 8.4 GHz with four telescopes in Japan. We obtain 3194 and 272 GRPs occurring at the main pulse and the interpulse phases, respectively. A few GRPs detected at both 0.3 and 8.4 GHz are the most wide-band samples ever reported. In the frequency range from 0.3 to 2.2 GHz, we find that about 70\% or more of the GRP spectra are consistent with single power laws and the spectral indices of them are distributed from $-4$ to $-1$. We also find that a significant number of GRPs have such a hard spectral index (approximately $-1$) that the fluence at 0.3 GHz is below the detection limit ("dim-hard" GRPs). Stacking light curves of such dim-hard GRPs at 0.3 GHz, we detect consistent enhancement compared to the off-GRP light curve. Our samples show apparent correlations between the fluences and the spectral hardness, which indicates that more energetic GRPs tend to show softer spectra. Our comprehensive studies on the GRP spectra are useful materials to verify the GRP model of fast radio bursts in future observations., Comment: 19 pages, 25 figures, accepted for publication in ApJ

We have developed a new method of data processing for radio telescope observation data to measure time-dependent temporal coherence, and we named it cross-correlation spectrometry (XCS). XCS is an autocorrelation procedure that expands time lags over the integration time and is applied to data obtained from a single-dish observation. The temporal coherence property of received signals is enhanced by XCS. We tested the XCS technique using the data of strong H2O masers in W3 (H2O), W49N and W75N. We obtained the temporal coherent lengths of the maser emission to be 17.95 $\pm$ 0.33 {\mu}s, 26.89 $\pm$ 0.49 {\mu}s and 15.95 $\pm$ 0.46 {\mu}s for W3 (H2O), W49N and W75N, respectively. These results may indicate the existence of a coherent astrophysical maser., Comment: 19 pages, 13 figures, 1 table, accepted for publication in Publications of the Astronomical Society of Japan

In order to explore any change caused by the G2 cloud approaching, we have monitored the flux density of Sgr A* at 22 GHz from Feb. 2013 to Aug. 2014 with a sub-array of Japanese VLBI Network . The observation period included the expected periastron dates. The number of observation epochs was 283 days. We have observed no significant microwave enhancement of Sgr A* in the whole observation period. The average flux density in the period is $S=1.23+/-0.33$ Jy. The average is consistent with the usually observed flux density range of Sgr A* at 22 GHz., Comment: Accepted for publication in Astrophysical Journal Letters, 14 pages, 1 figure

We present the results of the search for a correlation between giant radio pulses (GRPs) at 1.4 GHz and hard X-rays at 15-75 keV from the Crab pulsar. We made simultaneous ground and satellite observations of the Crab pulsar over 12 hours in three occasions in April 2010, March and September 2011, and got a sample of 1.3*10^4 main-pulse phase GRPs. From these samples we have found statistically marginal enhancement (21.5%, 2.70 sigma) of hard X-ray flux within +/- 1.5 degree phase angle of the synchronous peak of main-pulse phase GRPs. This enhancement, if confirmed, implicates that GRPs may accompany plasma density increases in the pulsar magnetosphere., Comment: 4 pages, 1 figure, 2 tables, submitted to the proceedings of APPC12 - the 12th Asia Pacific Physics Conference

We conducted radio detection observations at 8.4 GHz for 22 radio-loud broad absorption line (BAL) quasars, selected from the Sloan Digital Sky Survey (SDSS) Third Data Release, by a very-long-baseline interferometry (VLBI) technique. The VLBI instrument we used was developed by the Optically ConnecTed Array for VLBI Exploration project (OCTAVE), which is operated as a subarray of the Japanese VLBI Network (JVN). We aimed at selecting BAL quasars with nonthermal jets suitable for measuring their orientation angles and ages by subsequent detailed VLBI imaging studies to evaluate two controversial issues of whether BAL quasars are viewed nearly edge-on, and of whether BAL quasars are in a short-lived evolutionary phase of quasar population. We detected 20 out of 22 sources using the OCTAVE baselines, implying brightness temperatures greater than 10^5 K, which presumably come from nonthermal jets. Hence, BAL outflows and nonthermal jets can be generated simultaneously in these central engines. We also found four inverted-spectrum sources, which are interpreted as Doppler-beamed, pole-on-viewed relativistic jet sources or young radio sources: single edge-on geometry cannot describe all BAL quasars. We discuss the implications of the OCTAVE observations for investigations for the orientation and evolutionary stage of BAL quasars., Comment: 10 pages, no figure, 3 tables, accepted for publication in PASJ

Kashima Space Technology Center (KSTC) is making use of two kinds of software correlators, the multi-channel K5/VSSP software correlator and the fast wide-band correlator 'GICO3,' for geodetic and R&D VLBI experiments. Overview of the activity and future plans are described in this paper.

The Data Center at the National Institute of Information and Communications Technology (NICT) archives and releases the databases and analysis results processed at the Correlator and the Analysis Center at NICT. Regular VLBI sessions of the Key Stone Project VLBI Network were the primary objective of the Data Center. These regular sessions continued until the end of November 2001. In addition to the Key Stone Project VLBI sessions, NICT has been conducting geodetic VLBI sessions for various purposes, and these data are also archived and released by the Data Center.

This report summarizes the activities of the Analysis Center at National Institute of Information and Communications Technology (NICT) for the year 2012.

Two 11-m VLBI antennas at Kashima and Koganei are continuously operated and maintained by the National Institute of Information and Communications Technology (NICT). This report summarizes the status of these antennas, the staff, and the activities in 2012.

The Kashima 34-m radio telescope has been continuously operated and maintained by the National Institute of Information and Communications Technology (NICT) as a facility of the Kashima Space Technology Center (KSTC) in Japan. This brief report summarizes the status of this telescope, the staff, and activities during 2012.

GSI, NICT, OSO, and MRO have been engaged in Ultra-rapid dUT1 experiments since 2007 aiming at the technological possibility of real-time dUT1 results using the e-VLBI technique. We have already successfully determined dUT1 in less than four minutes after the end of an experimental Intensive session in 2008, and at present we routinely get the results within 30 minutes for regular Intensives. In 2009 we applied the technique to 24-hour sessions and continuously obtained dUT1 values by processing and analyzing Tsukuba Onsala data in near real-time. It showed a detailed behavior of UT1 variations, which could be very valuable for scientific study as well as for precise prediction of UT1-UTC.

We have developed a software library (KVTP-lib) for VLBI data transmission over the network with the VDIF (VLBI Data Interchange Format), which is the newly proposed standard VLBI data format designed for electronic data transfer over the network. The software package keeps the application layer (VDIF frame) and the transmission layer separate, so that each layer can be developed efficiently. The real-time VLBI data transmission tool sudp-send is an application tool based on the KVTP-lib library. sudp-send captures the VLBI data stream from the VSI-H interface with the K5/VSI PC-board and writes the data to file in standard Linux file format or transmits it to the network using the simple- UDP (SUDP) protocol. Another tool, sudp-recv , receives the data stream from the network and writes the data to file in a specific VLBI format (K5/VSSP, VDIF, or Mark 5B). This software system has been implemented on the Wettzell Tsukuba baseline; evaluation before operational employment is under way.

In this paper, we introduce our GPS-VLBI hybrid system and show the results of the first experiment which is now under way. In this hybrid system, GPS signals are captured by a normal GPS antenna, down-converted to IF signals, and then sampled by the VLBI sampler VSSP32 developed by NICT. The sampled GPS data are recorded and correlated in the same way as VLBI observation data. The correlator outputs are the group delay and the delay rate. Since the whole system uses the same frequency standard, many sources of systematic errors are common between the VLBI system and the GPS system. In this hybrid system, the GPS antenna can be regarded as an additional VLBI antenna having multiple beams towards GPS satellites. Therefore, we expect that this approach will provide enough data to improve zenith delay estimates and geodetic results.

One important outcome of the 7th International e-VLBI Workshop in Shanghai in June 2008 was the creation of a task force to study and recommend a universal VLBI data format that is suitable for both on-the-wire e-VLBI data transfer, as well as direct disk storage. This task force, called the VLBI Data Interchange Format (VDIF) Task Force, is the first part of a two-part effort, the second of which will address standardization of e-VLBI data-transmission-protocols. The formation of the VDIF Task Force was prompted particularly by increased e-VLBI activity and the difficulties encountered when data arrive at a correlator in different formats from various instruments in various parts of the world. The task force created a streaming packetized data format that may be used for real-time and non-realtime e-VLBI, as well as direct disk storage. The data may contain multiple channels of time-sampled data with an arbitrary number of channels, arbitrary #bits/sample up to 32, and real or complex data; data rates in excess of 100 Gbps are supported. Each data packet is completely self-identifying via a short header, and data may be decoded without reference to any external information. The VDIF task force has completed its work, and the VDIF standard was ratified at the 2009 e-VLBI workshop in Madrid.

Processing of space geodetic techniques should be carried out with consistent and utmost up-todate physical models. Therefore, c5++ is being developed, which will act as a framework under which dedicated space geodetic applications can be created. Due to its nature, combination of different techniques as well as automated processing of VLBI experiments will become possible with c5++.

Radar observations of two near-Earth asteroids were performed using a bi-static radar technique with Kashima 34-m antenna and Usuda 64-m antenna as receiving stations and Goldstone 70-m antenna as a transmitting station. The asteroid 6489 Golevka was observed on June 15, 1995 when its distance from the Earth became 0.048 AU and the radar echo from the asteroid was detected from the data observed with Kashima 34-m antenna. The success of the trans-continental bistatic radar observations became the first detection of a radar echo from a solar system object beyond Moon in Japan. The asteroid 4197 (1982 TA) was observed on October 24, 1996 when its distance to the Earth became 0.086 AU. The radar echo signal from the asteroid was detected from both of the data observed at Kashima and at Usuda. The received signal was coherently sampled and recorded at both stations. By using these data, interferometric data analysis was examined.