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The Radio Frequency Interference (RFI) generated by the surrounding environment will significantly reduce the observation efficiency of the large radio telescope. The Tian-Ma Radio Telescope (TMRT) has established a RFI monitoring system to keep watch on its surrounding RFI environment chronically in the L, S, C and X bands. The system consists of antennas, receivers, back-ends and control system. To achieve automatic system operation, we design and implement an automation software based on Tango Controls open source framework. This paper will briefly introduce the TMRT RFI Monitoring System (TRMS), and describe the functional design, architecture design and implementation of the automation software. Finally, With the help of this system, we carry out automatic remote monitoring of the RFI environment around the TMRT in the 1.2 GHz-12GHz frequency band, and then analyze and verify the observation results.

Full list of authors: Cui, Yu-Zhu; Hada, Kazuhiro; Kino, Motoki; Sohn, Bong-Won; Park, Jongho; Ro, Hyun-Wook; Sawada-Satoh, Satoko; Jiang, Wu; Cui, Lang; Honma, Mareki; Shen, Zhi-Qiang; Tazaki, Fumie; An, Tao; Cho, Ilje; Zhao, Guang-Yao; Cheng, Xiao-Peng; Niinuma, Kotaro; Wajima, Kiyoaki; Zhang, Ying-Kang; Kawaguchi, Noriyuki; Algaba, Juan-Carlos; Koyama, Shoko; Hirota, Tomoya; Yonekura, Yoshinori; Sakai, Nobuyuki; Xia, Bo; Jiang, Yong-Bin; Yu, Lin-Feng; Gou, Wei; Hwang, Ju-Yeon; Jiang, Yong-Chen; Sun, Yun-Xia; Jung, Dong-Kyu; Kim, Hyo-Ryoung; Kim, Jeong-Sook; Kobayashi, Hideyuki; Lee, Jee-Won; Lee, Jeong-Ae; Zhang, Hua; Li, Guang-Hui; Xu, Zhi-Qiang; Li, Peng; Oh, Jung-Hwan; Oh, Se-Jin; Oh, Chung-Sik; Oyama, Tomoaki; Roh, Duk-Gyoo; Shibata, Katsunori-M.; Guo, Wen; Zhao, Rong-Bing; Zhong, Wei-Ye; Wang, Jin-Qing; Yang, Wen-Jun; Yan, Hao; Yeom, Jae-Hwan; Li, Bin; Li, Xiao-Fei; Yuan, Jian-Ping; Dong, Jian; Chen, Zhong; Akiyama, Kazunori; Asada, Keiichi; Byun, Do-Young; Hagiwara, Yoshiaki; Hodgson, Jeffrey; Jung, Tae-Hyun; Kim, Kee-Tae; Lee, Sang-Sung; Yi, Kunwoo; Liu, Qing-Hui; Liu, Xiang; Lu, Ru-Sen; Nakamura, Masanori; Trippe, Sascha; Wang, Na; Wang, Xue-Zheng; Zhang, Bo, The East Asian Very Long Baseline Interferometry (VLBI) Network (EAVN) is a rapidly evolving international VLBI array that is currently promoted under joint efforts among China, Japan and Korea. EAVN aims at forming a joint VLBI Network by combining a large number of radio telescopes distributed over East Asian regions. After the combination of the Korean VLBI Network (KVN) and the VLBI Exploration of Radio Astrometry (VERA) into KaVA, further expansion with the joint array in East Asia is actively promoted. Here we report the first imaging results (at 22 and 43 GHz) of bright radio sources obtained with KaVA connected to Tianma 65-m and Nanshan 26-m Radio Telescopes in China. To test the EAVN imaging performance for different sources, we observed four active galactic nuclei (AGN) having different brightness and morphology. As a result, we confirmed that the Tianma 65-m Radio Telescope (TMRT) significantly enhances the overall array sensitivity, a factor of 4 improvement in baseline sensitivity and 2 in image dynamic range compared to the case of KaVA only. The addition of the Nanshan 26-m Radio Telescope (NSRT) further doubled the east-west angular resolution. With the resulting high-dynamic-range, high-resolution images with EAVN (KaVA+TMRT+NSRT), various fine-scale structures in our targets, such as the counter-jet in M87, a kink-like morphology of the 3C 273 jet and the weak emission in other sources are successfully detected. This demonstrates the powerful capability of EAVN to study AGN jets and to achieve other science goals in general. Ongoing expansion of EAVN will further enhance the angular resolution, detection sensitivity and frequency coverage of the network. © 2021 National Astronomical Observatories, CAS and IOP Publishing Ltd., TMRT is operated by Shanghai Astronomical Observatory. NSRT is operated by Xinjiang Astronomical Observatory. KVN is a facility operated at by the Korea Astronomy and Space Science Institute. VERA is a facility operated at National Astronomical Observatory of Japan in collaboration with associated universities in Japan. This work is supported by The Graduate University for Advanced Studies (SOKENDAI). Y.C. is supported by the Japanese Government (MEXT) Scholarship. This work is supported by JSPS KAKENHI Grant Numbers JP18K03656 (M.K.), JP18H03721 (K.N., K.H. and M.K.), JP19H01943 (K.H., F.T. and Y.H.) and JP18KK0090 (K.H. and F.T.). K.H. is supported by the Mitsubishi Foundation (grant number 201911019). J.P. is supported by an EACOA Fellowship awarded by the East Asia Core Observatories Association, which consists of the Academia Sinica Institute of Astronomy and Astrophysics, the National Astronomical Observatory of Japan, the Center for Astronomical Mega-Science, the Chinese Academy of Sciences, and the Korea Astronomy and Space Science Institute. J.P. and I.C. acknowledge the financial support from the National Research Foundation (NRF) of Korea via Global Ph.D. Fellowship Grant 2014H1A2A1018695 and 2015H1A2A1033752, respectively. S.T. acknowledges support from the NRF via Grant 2019R1F1A1059721. This work is supported by the Major Program of the National Natural Science Foundation of China (NSFC, Grant Nos. 11590780 and 11590784), the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KJCX1-YW-18), the Scientific Program of Shanghai Municipality (08DZ1160100) and Key Laboratory for Radio Astronomy, CAS. W.J. acknowledges support from NSFC (Grant No. 11803071). L.C. is supported by the National Key R&D Program of China (Grant No. 2018YFA0404602), the CAS 'Light of West China' Program (Grant No. 2018-XBQNXZ-B-021), the NSFC (Grant Nos. U2031212 and 61931002) and the Youth Innovation Promotion Association of the CAS (Grant No. 2017084). J.C.A. acknowledges support from Fundamental Research Grant Scheme (FRGS) FRGS/1/2019/STG02/UM/02/6. R.S. Lu is supported by the Max Planck Partner Group of the MPG and the CAS and acknowledges the support by the Key Program of the NSFC (Grant No. 11933007) and the Research Program of Fundamental and Frontier Sciences, CAS (Grant No. ZDBS-LY-SLH011)., With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709.

In 2020, China will launch a Mars spacecraft composed of anorbiter and lander/rover. In this paper, the tracking techniques of the Marsspacecraft for a large radio telescope are analyzed and verifiedusing the Shanghai 65 m radio telescope (Tianma telescope). The measurementresults indicate that the pointing error caused by thermal deformation ofthe antenna body, atmospheric refraction, and the light-time effect should beconsidered when a large radio telescope is used to track the Marsspacecraft. When the light-time effect is not taken into account, thereceiving power is reduced by approximately 0.8 dB. When the elevation offset is 36and 72 arcsec, the reception capacity of the Tianma telescope is reduced byapproximately 0.8 and 3.5 dB, respectively. The results of this study thus have importantimplications for the Mars exploration.

In this paper, we reported the measured results of the antenna efficiency, sensitivity, and system noise temperature of the TM65m radio telescope. The key parameters describing a radio astronomy receiving system were introduced at first. Then, we discussed the measurement methods and the measuring errors. Finally, the measured results of the antenna efficiency, sensitivity, and system noise temperature performances at the L, S, C, and X bands were given. The results show that the efficiency and SEFD (System Equivalent Flux Density) decrease dramatically at both low and high elevations when the position of the subreflector is fixed. The antenna efficiencies at the C and X bands can be raised to 60% and more in the whole elevation range when the subreflector (servo) model is activated. The system noise temperature is independent to the subreflector model. Among the four wavebands, the C-band sensitivity and system noise temperature are optimal.

The Five-hundred-meter Aperture Spherical radio Telescope (FAST) is the largest single-dish radio telescope in the world, and is now being commissioned after the first light in September 2016. Very long baseline interferometry (VLBI) is among the key science topics according to the original design. The FAST VLBI system has been established, and the first VLBI fringe has been successfully obtained. FAST will significantly improve the sensitivity of the existing VLBI networks in the future, and some science projects in need of high sensitivity will benefit from its participation.

We have investigated the mode-changing properties of PSR B0329+54 using 31 epochs of simultaneous 13 cm/3 cm single-pulse observations obtained with Shanghai Tian Ma 65 m telescope. The pulsar was found in the abnormal emission mode 17 times, accounting for ~13% of the 41.6 hours total observation time. Single pulse analyses indicate that mode changes took place simultaneously at 13 cm/3 cm within a few rotational periods. We detected occasional bright and narrow pulses whose peak flux densities were 10 times higher than that of the integrated profile in both bands. At 3 cm, about 0.66% and 0.27% of single pulses were bright in the normal mode and abnormal mode respectively, but at 13 cm the occurrence rate was only about 0.007%. We divided the pulsar radiation window into three components (C1, C2 and C3) corresponding to the main peaks of the integrated profile. The bright pulses preferentially occurred at pulse phases corresponding to the peaks of C2 and C3. Fluctuation spectra showed that C2 had excess red noise in the normal mode, but broad quasi-periodic features with central frequencies around 0.12 cycles/period in the abnormal mode. At 3 cm, C3 had a stronger quasi-periodic modulation centered around 0.06 cycles/period in the abnormal mode. Although there were some asymmetries in the two-dimensional fluctuation spectra, we found no clear evidence for systematic subpulse drifting. Consistent with previous low-frequency observations, we found a very low nulling probability for B0329+54 with upper limits of 0.13% and 1.68% at 13 cm/3 cm respectively., Comment: 16 pages, 10 figures, 3 tables

A sub-reflector system of the TianMa 65 m radio telescopes has been installed in order to compensate for the gravitational deformation of the sub-reflector support and the main reflector. The position and attitude of the sub-reflector are variable in order to improve the pointing performance and the efficiency at different elevations. A model has been constructed to determine the position and attitude of the sub-reflector with elevation. Test results show that the sub-reflector model can effectively improve the efficiency of the 65 m radio telescope at both high and low elevations, where the efficiency can be improved by 20% and 15%, respectively. At X band, the aperture efficiency of the radio telescope reaches more than 60% over the entire elevation range. Pointing deviations caused by the sub-reflector model are consistent with the grasp simulation results.

We report the detection of widespread CH$_2$OHCHO and HOCH$_2$CH$_2$OH emission in Galactic center giant molecular cloud Sagittarius B2 using the Shanghai Tianma 65m Radio Telescope. Our observations show for the first time that the spatial distribution of these two important prebiotic molecules extends over 15 arc-minutes, corresponding to a linear size of approximately 36 pc. These two molecules are not just distributed in or near the hot cores. The abundance of these two molecules seems to decrease from the cold outer region to the central region associated with star-formation activity. Results present here suggest that these two molecules are likely to form through a low temperature process. Recent theoretical and experimental studies demonstrated that prebiotic molecules can be efficiently formed in icy grain mantles through several pathways. However, these complex ice features cannot be directly observed, and most constraints on the ice compositions come from millimeter observations of desorbed ice chemistry products. These results, combined with laboratory studies, strongly support the existence of abundant prebiotic molecules in ices., 20 pages, 7 figures, accepted by ApJ

The emission geometries, e.g. the emission region height, the beam shape, and radius-to-frequency mapping, are important predictions of pulsar radiation model. The multi-band radio observations carry such valuable information. In this paper, we study two bright pulsars, (PSRs B0329+54 and B1642-03) and observe them in high frequency (2.5 GHz, 5 GHz, and 8 GHz). The newly acquired data together with historical archive provide an atlas of multi-frequency profiles spanning from 100 MHz to 10 GHz. We study the frequency evolution of pulse profiles and the radiation regions with the these data. We firstly fit the pulse profiles with Gaussian functions to determine the phase of each component, and then calculate the radiation altitudes of different emission components and the radiation regions. We find that the inverse Compton scattering (ICS) model can reproduce the radiation geometry of these two pulsars. But for PSR B0329+54 the radiation can be generated in either annular gap (AG) or core gap (CG), while the radiation of PSR B1642-03 can only be generated in the CG. This difference is caused by the inclination angle and the impact angle of these two pulsars. The relation of beaming angle (the angle between the radiation direction and the magnetic axis) and the radiation altitudes versus frequency is also presented by modelling the beam-frequency evolution in the ICS model. The multi-band pulse profiles of these two pulsars can be described well by the ICS model combined with the CG and AG.

Integrated pulse profiles at 8.6~GHz obtained with the Shanghai Tian Ma Radio Telescope (TMRT) are presented for a sample of 26 pulsars. Mean flux densities and pulse width parameters of these pulsars are estimated. For eleven pulsars these are the first high-frequency observations and for a further four, our observations have a better signal-to-noise ratio than previous observations. For one (PSR J0742-2822) the 8.6~GHz profiles differs from previously observed profiles. A comparison of 19 profiles with those at other frequencies shows that in nine cases the separation between the outmost leading and trailing components decreases with frequency, roughly in agreement with radius-to-frequency mapping, whereas in the other ten the separation is nearly constant. Different spectral indices of profile components lead to the variation of integrated pulse profile shapes with frequency. In seven pulsars with multi-component profiles, the spectral indices of the central components are steeper than those of the outer components. For the 12 pulsars with multi-component profiles in the high-frequency sample, we estimate the core width using gaussian fitting and discuss the width-period relationship., Comment: 33 pages, 49 figures, 5 Tables; accepted by ApJ

This paper focuses on the measurement of the main reflector gravity deformation and sub-reflector position change on Tianma 65 m (TM65 m) radio telescope. Firstly the paper summarizes the methods of principal measurement. Microwave holography and cross scan pattern are disscussed. Then the gravity deformation of the main reflector over the entire elevation measured by VLBI method is discribed. The measurement accuracy is also estimated. At last, the gravity model is constructed and compared with the simulation. They agree with each other. The formulas along with the simulation give a description between the offsets of feed, sub-reflector and the aperture phase. The sub-reflector position ofTM65 m is obtained by the least square method that applied on the aperutre phase and the formulas. The sub-reflector positions measured are consistent with that of the traditional amplitude method in X , Y and Z directions. This method provides a different way to measure the position model of the sub-reflector.

We report Shanghai Tian Ma Radio Telescope detections of several long carbon-chain molecules at C and Ku band, including HC3N, HC5N, HC7N, HC9N, C3S, C6H and C8H toward the starless cloud Serpens South 1a. We detected some transitions (HC9N J=13-12 F=12-11 and F=14-13, H13CCCN J=2-1 F=1-0 and F=1-1, HC13CCN J=2-1 F=2-2, F=1-0 and F=1-1, HCC13CN J=2-1 F=1-0 and F=1-1) and resolved some hyperfine components (HC5N J=6-5 F=5-4, H13CCCN J=2-1 F=2-1) for the first time in the interstellar medium. The column densities of these carbon-chain molecules in a range of 10^{12}-10^{13} cm^{-2} are comparable to two carbon-chain molecule rich sources, TMC-1 and Lupus-1A. The abundance ratios are 1.00:(1.11\pm0.15):(1.47\pm0.18) for [H13CCCN]:[HC13CCN]:[HCC13CN]. This result implies that the 13C isotope is also concentrated in the carbon atom adjacent to the nitrogen atom in HC3N in Serpens south 1a, which is similar to TMC-1. The [HC3N]/[H13CCCN] ratio of 78\pm9, the [HC3N]/[HC13CCN] ratio of 70\pm8, and the [HC3N]/[HCC13CN] ratio of 53\pm4 are also comparable to those in TMC-1. In any case, Serpens South 1a proves a testing ground for understanding carbon-chain chemistry., 16 pages, 4 figures, accepted for publication in ApJ

In the paper, the main factors influencing pointing precision of large radio telescopes are discussed. Then the TianMa radio telescope (TM65 m) is selected for demonstration. The methods of detecting and separating the pointing errors which produce in all the segments from the subreflector to the track rail of the telescope are introduced. They includes: (1) half power point tracking to evaluate the overall antenna pointing error; (2) detecting the pointing error due to position changing of the subreflector support; (3) detecting the deviation of the antenna mount due to temperature changing; (4) detecting the asynchronization of the mechanical axis and the encode axis; (5) high precision pointing modeling based on the uneveness of track rail. A few measurement methods and their respective results are discussed.

In this paper, we report radio observations of the Galactic Center magnetar PSR J1745-2900 at six epochs between June and October, 2014. These observations were carried out using the new Shanghai Tian Ma Radio Telescope at a frequency of 8.6 GHz. Both the flux density and integrated profile of PSR J1745-2900 show dramatic changes from epoch to epoch showing that the pulsar was in its "erratic" phase. On MJD 56836, the flux density of this magnetar was about 8.7 mJy, which was ten times large than that reported at the time of discovery, enabling a single-pulse analysis. The emission is dominated by narrow "spiky" pulses which follow a log-normal distribution in peak flux density. From 1913 pulses, we detected 53 pulses whose peak flux density is ten times greater than that of the integrated profile. They are concentrated in pulse phase at the peaks of the integrated profile. The pulse widths at the 50% level of these bright pulses was between 0.2 to 0.9 deg, much narrower than that of integrated profile (~12 deg). The observed pulse widths may be limited by interstellar scattering. No clear correlation was found between the widths and peak flux density of these pulses and no evidence was found for subpulse drifting. Relatively strong spiky pulses are also detected in the other five epochs of observation, showing the same properties as that detected in MJD 56836. These strong spiky pulses cannot be classified as "giant" pulses but are more closely related to normal pulse emission., Comment: 21 papes, 7 figures, accepted by ApJ

Microwave holography is a valuable technique used in the diagnostics and adjustment of large antennas. A brief outline of the technique is given first. Then detail simulations for surface deviation and sub-reflectorr offsets solving method that applied on the TianMa 65 m are described. After several rounds of adjustments, a reflector surface accuracy 0.28 mm and repeated measurement error 0.13 mm were achieved for the TM65 antenna. At last the antenna efficiency on Ka band was measured at elevations between 45 and 60 degrees. The efficiency improved from 37% to 56% when the active surface model is loaded that is consistent with the theoretical predictions.