We report on the current status of the radial velocity monitoring of nearby OB stars to look for binaries with small mass ratios. The combined data of radial velocities using the domestic 1-2 m-class telescopes seems to confirm the variations of radial velocities in a few weeks for four out of ten target single-lined spectroscopic binaries. More data are needed to estimate the exact periods and mass distributions.

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Optical spectroscopic observations were carried out for transit events of hot-Jupiters HATP-16b and HAT-P-39b with 2m Nayuta Telescope and a narrow-band imager and spectrograph, LISS. We have observed HAT-P-16b for 229 minutes including 184 minutes of the transit event, and HAT-P-39b for 390 minutes including 251 minutes transit event. We used a very low resolution grism and a 10&qout; width slit, and obtained spectra with the spectral resolution of 12. Nearby stars were also observed simultaneously as a reference star. Transit events are detected for both objects in the wavelength between 620 nm and 885 nm. Transit depth is 0.0120±0.0006 and the radius ratio of the planet to the star is 0.1097±0.0029 for HAT-P-16b. Transit depth is 0.0093±0.0007 and radius ratio of the planet to the star is 0.0966+0.0034 － 0.0036 for HAT-P-39b. We do not find clear evidence for wavelength dependence of transit depths for both planets.

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We redeveloped the polarimetry mode for the Nishiharima Infrared Camera (NIC). A calcite polarizing beam displacer was adopted. The holder for the displacer was designed considering anisotropy in thermal expansion of calcite. We installed the new polarizing beam displacer into the cryostat in February, 2018. Observations for unpolarized standard stars yielded instrumental (including telescope) polarization degrees of 0.01±0.37% (J), 0.02±0.82% (H), and 0.04±0.39% (Ks). We did not find any significant dependence of the instrumental polarization on either the image position, the rotator’s angle, or the telescope altitude. Our evaluation shows that the NIC has a potential to detect a 1% polarization degree in at least J and Ks bands.

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As one of the educational dissemination activities of Nishi-Harima Astronomical Observatory, we have conducted astronomy practical training for high school and undergraduate students. We have conducted a questionnaire aiming at survey of satisfaction from the users and improvement of the quality since July 2015. In this paper, we surveyed the questionnaires from July 2015 to October 2018 and investigated to the satisfaction from the users for our training menu. The questionnaire was conducted for a total of 140 schools and organizations, and 89 responses were obtained. The recovery rate was 64%. As a result, it was revealed that the majority of the users answered that they were satisfied with the content of the practical training. In addition, we found that the satisfaction level of ”daytime observation of stars and sun”, ”astronomy lecture”, ”night observation practice” and the overall practice increased in recent years. On the other hand, we found that ”tour of the observation with Nayuta” showed a downward trend in satisfaction and there is room for improvement. We also conducted a survey on the difficulty level of each practice menu. As a result, it was found that the answer choosing ”proper” reached 86 % of the total number of responses. Considering the trend of the satisfaction from the users and the answer for the difficulty level, we concluded that our astronomy practice training at Nishi-Harima Astronomical Observatory is almost as expected by the user.

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Some observations have indicated that the binary frequency of pre-main-sequence stars is higher than that of main-sequence stars. Several hot jupiters which are gas planets with the orbital period of days are discovered in the main-sequence stars （e.g., Mayor & Queloz 1995）. Most of the main-sequence stars may be formed as the binary system. The difference of the binary rate between pre-main-sequence stars and main-sequence stars may be consistent with the frequency of the hot jupiter. We think that a binary formation correlates with a planet formation. Toyota et al. (2009) indicated that the standard deviations of the radial velocity of ADS 3085 A and ADS 3085 B are twice larger than the typical uncertainties of the velocities. The radial-velocity variation with the primary and secodary component may be caused by the orbital motion of the unknown companion object, respectively. We follow-up the radial velocities of ADS 3085 A and B from December 2007 to December 2009. We searched for the period of the radial velocity with the Lomb–Scargle algorithm (Scargle 1982). The radial velocities of ADS 3085 A and B may have the periodic variations with 7.7 d and 5.2 d, respectively. In both A and B, the cool spots on the surface of the star are moving with the stellar rotation because the chromospheric activity is active and the Hipparcos photometric data shows the magnitude variation. Since the radial velocity of ADS 3085 A strongly correlates with the chromospheric activity, the radial-velocity variation is caused by the stellar activity. In ADS 3085 B, although we do not show the correlation between radial-velocity variation and the chromospheric activity, the stellar activity may explains the radial-velocity variation.

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“Citizen science” is a method for citizens to actively and directly involve scientific researches. In order to organize “citizen science” appropriately, one must concern various factors on active participants; i.e. motivation and environment. Recent movements on open data, not only for natural science but also humanities and social science, encourage the utilization of data beyond specialists, which can drive an interdisciplinary issue asking citizens’ involvements. Since 2016, in National Institute of Japanese Literature, we have organized three workshops, which public participants are asked to search for keywords related to astronomical events and natural disasters from historical materials. Based on our questionnaire analysis at these workshops, participants are motivated on, e.g., interests on local historical materials and surprise at the combination of history and astronomy. Therefore, this interdisciplinary workshop could be concluded as a successful case to encourage the citizens’ involvements beyond their original interests. The key to support “citizen science” is on construction of reliable database, which must be planned not only simply based on the accuracy of data made by public under the guidance, but also with concerns upon generations and skill levels of the participants.

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We constructed the Exposure Time Calculator (ETC) for the Medium And Low-dispersion Long-slit Spectrograph (MALLS) and the Nishi-harima Infrared Camera (NIC) on board the 2 m Nayuta telescope at the Nishi-Harima Astronomical Observatory. This ETC has been enabled to calculate a probable signal-to-noise ratio based on a V magnitude and an exposure time. It can also calculate a required exposure time based on a V magnitude and a signal-to-noise ratio. At MALLS ETC, we can get more information of the total observation time including time getting flat and comparison data and time finding and pointing target. At NIC ETC, we can compare the difference between 2 read out mode.

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