Using high temporal and high spatial resolution observations taken by the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory, we present the detailed observational analysis of a high quality quasi-periodic fastpropagating (QFP) magnetosonic wave that was associated with the eruption of a magnetic flux rope and a GOES C5.0 flare. For the first time, we find that the QFP wave lasted during the entire flare lifetime rather than only the rising phase of the accompanying flare as reported in previous studies. In addition, the propagation of the different parts of the wave train showed different kinematics and morphologies. For the southern (northern) part, the speed, duration, intensity variation are about 875 ± 29 (1485 ± 233) km s −1 , 45 (60) minutes, and 4% (2%), and the pronounced periods of them are 106 ± 12 and 160 ± 18 (75 ± 10 and 120 ± 16) seconds, respectively. It is interesting that the northern part of the wave train showed obvious refraction effect when they pass through a region of strong magnetic field. Periodicity analysis result indicates that all the periods of the QFP wave can be found in the period spectrum of the accompanying flare, suggesting their common physical origin. We propose that the quasi-periodic nonlinear magnetohydrodynamics process in the magnetic reconnection that produces the accompanying flare should be important for exciting of QFP wave, and the different magnetic distribution along different paths can account for the different speeds and morphology evolution of the wave fronts.

We installed two sets of Astronomical Site Monitoring Systems (ASMSs) at Lijiang Observatory (GMG), for the running of the 2.4-meter Lijiang optical telescope (LJT) and the 1.6-meter Multi-channel Photometric Survey Telescope (Mephisto). The Mephisto is under construction. The ASMS has been running on robotic mode since 2017. The core instruments: Cloud Sensor, All-Sky Camera and Autonomous-DIMM that are developed by our group, together with the commercial Meteorological Station and Sky Quality Meter, are combined into the astronomical optical site monitoring system. The new Cloud Sensor’s Cloud-Clear Relationship is presented for the first time, which is used to calculate the All-Sky cloud cover. We designed the Autonomous-DIMM located on a tower, with the same height as LJT. The seeing data have been observed for a full year. ASMS’s data for the year 2019 are also analysed in detail, which are valuable to observers.

The observational analysis is performed to study the excitation mechanism and the propagation properties of a quasi-periodic fast-propagating (QFP) magnetosonic wave. The QFP wave was associated with the eruption of a nearby mini-filament and a small B4 GOES flare, which may indicate that the generation of a QFP wave do not need too much flare energy. The propagation of the QFP wave was along a bundle of funnelshaped open loops with a speed of about 1100 ± 78 km s −1 , and an acceleration of -2.2 ± 1.1 km s −2 . Periodicity analysis indicates that the periods of the QFP wave are 43 ± 6, 79 ± 18 second. For the first time, we find that the periods of the QFP wave and the accompanying flare are inconsistent, which is different from the findings as reported in previous studies. We propose that the present QFP wave was possibly caused by the mechanism of dispersive evolution of an initially broadband disturbance resulted from the nearby mini-filament eruption.

The Large Optical/infrared Telescope (LOT) is a ground-based 12 m diameter optical/infrared telescope which is proposed to be built in the western part of China in the next decade. Based on satellite remote sensing data, along with geographical, logistical and political considerations, three candidate sites were chosen for ground-based astronomical performance monitoring. These sites include: Ali in Tibet, Daocheng in Sichuan and Muztagh-ata in Xinjiang. Up until now, all three sites have continuously collected data for two years. In this paper, we will introduce this site testing campaign, and present its monitoring results obtained during the period between March 2017 and March 2019.

A large ground-based optical/infrared telescope is being planned for a world-class astronomical site in China. The cloud-free night percentage is the primary meteorological element for evaluation of the sites. The data from satellites GMS, NOAA, and MODIS were used in this research, covering the period from 1996 to 2015. Our data analysis benefits from overlapping results from different independent teams as well as a uniform analysis of selected sites using GMS+NOAA data. Although significant ground-based monitoring is needed to validate these findings, we identify three different geographical regions with a high percentage of cloud-free conditions (∼83% on average) slightly lower than the Mauna Kea and Armazones sites (∼85% on average) chosen for the large international projects TMT and ELT respectively.

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Excellent sites are necessary for developing and installing ground-based large telescopes. For very-high-resolution solar observations, it had been unclear whether there exist good candidate sites in the west areas in China, including the Tibetan Plateau and the Pamirs Plateau. The project of solar site survey for the next-generation large solar telescopes, i.e., the Chinese Giant Solar Telescope (CGST) and the large coronagraph, has been launched since 2011. Based on the close collaboration among Chinese solar society and the scientists from NSO, HAO and other institutes, we have successfully developed the standard instruments for solar site survey and applied them to more than 50 different sites distributed in Xinjiang, Tibet, Qinghai, Sichuan, Yunnan and Ningxia provinces. We have built two long-term monitoring sites in Tibet and the large Shangri-La to take systematic site data. Clear evidence, including the key parameters of seeing factor, sky brightness and water vapor content, has indicated that a few potential sites in the large Tibetan areas should obtain the excellent astronomical conditions for our purpose to develop CGST and large coronagraph. We introduce the fresh site survey results in this report.

Two-dimentional (2D) solar coronal magnetogram is difficult to be measured directly till now. From the previous knowledge, a general relation has been noticed that the brighter green-line brightness for corona, the higher coronal magnetic field intensity may correspond to. To try to further reveal the relationship between coronal green line brightness and magnetic field intensity, we use the 2D coronal images observed by Yunnan Observatories Green-line Imaging System (YOGIS) of the 10-cm Lijiang coronagraph and the coronal magnetic field maps calculated from the current-free extrapolations with the photospheric magnetograms taken by Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO) spacecraft. In our analysis, we identified the coronal loop structures and construct two-dimensional maps of the corresponding magnetic field intensity in the plane of the sky (POS) above the limb. We derive the correlation coefficients between the coronal brightness and the magnetic field intensity for different heights of coronal layers. We further use a linear combination of a Gaussian and a quadratic profile to fit the correlation coefficients distribution, finding a largest correlation coefficient of 0.81 near 1.1 $R_\odot$ (solar radii) where is almost the top of the closed loop system. For the small closed loop system identified, the correlation coefficient distributions crossing and covering the loop are calculated. We also investigate the correlation with extended heliocentric latitude zones and long period of one whole Carrington Rotation, finding again that the maximum correlation coefficient occurs at the same height. It is the first time for us to find that the correlation coefficients are high (all are larger than 0.8) at the loop-tops and showing poor correlation coefficients with some fluctuations near the feet of the coronal loops. Our findings indicate that, for the heating of the low-laltitude closed loops, both DC (dissipation of currents) and AC (dissipation of Alfven and magnetosonic waves) mechanisms should act simultaneously on the whole closed loop system while the DC mechanisms dominate in the loop-top regions. Therefore, in the distributions of the correlation coefficients with different heights of coronal layers , for both large- and small-scale latitude ranges, the coefficients can reach their maximum values at the same coronal height of 1.1 $R_\odot$, which may indicate the particular importance of the height of closed loops for studying the coupling of the local emission mechanism and the coronal magnetic fields, which maybe helpful for studying the origin of the low-speed solar wind.