Atmospheric extinction coefficients and night sky brightness at the Xuyi Observation Station

We present measurements of the optical broadband atmospheric extinction coefficients and the night sky brightness at the Xuyi Observation Station of Purple Mountain Observatory. The measurements are based on CCD imaging data taken in the Sloan Digital Sky Survey＇s g, r and i bands with the Xuyi 1.04/1.20m Schmidt Telescope for the Xuyi Schmidt Telescope Photometric Survey of the Galactic Anticenter （XSTPS-GAC）, the photometric part of the Digital Sky Survey of the Galactic Anti-center （DSS-GAC）. The data were collected during more than 140 winter nights from 2009 to 2011. We find that the atmospheric extinction coefficients for the g, r and i bands are 0.69, 0.55 and 0.38 mag/airmass, respectively, based on observations taken on several photometric nights. The night sky brightness determined from images with good quality has median values of 21.7, 20.8 and 20.0 mag arcsec-2 and reaches 22.1, 21.2 and 20.4mag arcsec-2 under the best observing conditions for the g, r and i bands, respectively. The relatively large extinction coefficients compared with other good astronomical observing sites are mainly due to the relatively low elevation （i.e. 180 m） and high humidity at the station.

Natural Philosophy, Inventions and Religion in the Correspondence between John Locke and Nicolas Toinard （1678-1704）

The paper examines the copious correspondence between the English philosopher John Locke （1632-1704） and the French intellectual Nicolas Toinard （1629-1706）; Locke made the acquaintance of Toinard in Paris in 1677 or early in 1678, and the latter remained his lifelong friend and most assiduous correspondent. An Orleanais and a devout Catholic, Toinard combined an intense interest in the Scriptures with an enthusiasm for experimental science and inventions of every kind; he introduced Locke to all the French official institutions and to a number of private laboratories. Toinard＇s principal work, Evangeliorum Harmonia Graeco-Latina, was greatly appreciated by Locke for its new method. The paper attempts to explore the bulk of this correspondence in detail, giving an account of the wide range of topics dealt with in the two hundred letters; it is divided into four paragraphs referring, respectively, to the years 1678-1679, 1679-1681, 1681-1686, and1686-1704. The perspective is diachronic; on some occasions, the focus is on a particular topic which is the object of prolonged discussion between the two correspondents. In the conclusion, attention is drawn to the relevance of this correspondence in the context of the 17th century and of Locke＇s philosophical thought.

Natural Philosophy, Inventions and Religion in the Correspondence between John Locke and Nicolas Toinard （1678-1704）

The paper examines the copious correspondence between the English philosopher John Locke （1632-1704） and the French intellectual Nicolas Toinard （1629-1706）; Locke made the acquaintance of Toinard in Paris in 1677 or early in 1678, and the latter remained his lifelong friend and most assiduous correspondent. An Orl6anais and a devout Catholic, Toinard combined an intense interest in the Scriptures with an enthusiasm for experimental science and inventions of every kind; he introduced Locke to all the French official institutions and to a number of private laboratories. Toinard＇s principal work, Evangeliorum Harmonia Graeco-Latina, was greatly appreciated by Locke for its new method. The paper attempts at exploring the bulk of this correspondence in detail, giving an account of the wide range of topics dealt with in the two hundred letters; it is divided into four paragraphs referring, respectively, to the years 1678-1679, 1679-1681, 1681-1686, and1686-1704. The perspective is diachronic; in some occasions, the focus is on a peculiar topic which is the object of prolonged discussion between the two correspondents. In the conclusion, attention is drawn to the relevance of this correspondence in the context of the 17th century and of Locke＇s philosophical thought.

First observations of the water masers with the Urumqi 25m radio telescope

A new radio spectral receiving system has been installed on the 25 m radio telescope of the Urumqi Astronomical Observatory. The back end is a surface acoustic wave chirp transform spectrometer (SAW CZT), used for the first time in radio astronomy. The calibration of the line observations has carefully been investigated for the new-type spectrometer. In order to test the feasibility of the prototype spectrometer, we observed water maser emission from a number of known Galactic sources. We describe the observed spectra of W49N, W3(OH), 2248+600 and 1909+090. We found that W49N spectrum showed high-velocity features ranging from -330 to 146 km s-1. In comparison with the spectra observed by Medicina, the feature at the LSR velocity -52 km s-1 in the W3(OH) presented the rapid variation in flux density.

Ground-layer adaptive optics for the New Vacuum Solar Telescope:Instrument description and first results

Ground-layer adaptive optics(GLAO)has shown its potential for use in solar observation owing to its wide field-of-view(FOV)correction.A high-order GLAO system that consists of a multiple direction Shack-Hartmann wavefront sensor(WFS),a realtime controller with a multi-CPU processor,and a 151-element deformable mirror was developed for the 1-m New Vacuum Solar Telescope at Yunnan Observatories,Chinese Academy of Sciences.A hexagonal microlens with 9×8 subapertures is employed in the WFS.The detection FOV is 42′′×37′′,in which 9(3×3)guide regions are extracted for multiple direction wavefront sensing with a frame rate of up to 2200 Hz.To our knowledge,this is the first professional solar GLAO system used as a regularly operating instrument for scientific observations.Its installation and adjustment were performed in the summer of 2021.In this article,a detailed account of the GLAO system and its first light results and a comprehensive analysis of the performance of the GLAO system are provided.The results show that this system can effectively improve the imaging quality after compensating for the wavefront aberration due to ground-layer turbulence.

The Giant Radio Array for Neutrino Detection(GRAND):Science and design

The Giant Radio Array for Neutrino Detection(GRAND)is a planned large-scale observatory of ultra-high-energy(UHE)cosmic particles,with energies exceeding 10~8 Ge V.Its goal is to solve the long-standing mystery of the origin of UHE cosmic rays.To do this,GRAND will detect an unprecedented number of UHE cosmic rays and search for the undiscovered UHE neutrinos and gamma rays associated to them with unmatched sensitivity.GRAND will use large arrays of antennas to detect the radio emission coming from extensive air showers initiated by UHE particles in the atmosphere.Its design is modular:20 separate,independent sub-arrays,each of 10000 radio antennas deployed over 10000 km^2.A staged construction plan will validate key detection techniques while achieving important science goals early.Here we present the science goals,detection strategy,preliminary design,performance goals,and construction plans for GRAND.

Comparison between the time-integrated spectrum and the peak time spectrum of gamma-ray bursts and possible implications

The mono-frequency peak luminosity and the corresponding photon energy of the time-integrated （L~, Eg） and peak time （L~, ffp） vfv spectra were derived for a sample of 38 redshift-known Fermi GRBs by fitting the spectra with the Band function. It was found that Ept is generally consistent with Ep, and Lp is averagely three times larger than Lp. The slope of the Lp1 -Etp relation was consistent with that of the Lps - Eps relation. The photon indices in the peak time spectrum, particularly, the index of the low energy end was, were statistically larger than that in the time-integrated spectrum. These results indicate that Lp and Ep are dominated by Lp1 and Ept, respectively. The difference of the spectral indices between the time-integrated and peak time spectra may be because of the overlap effect of a series of time-resolved spectra within a GRB. Our simulations, which were based on the observed spectral evolution and correlation between the energy flux and the peak energy within individual GRBs support our speculations. The Lt - Et, relation may be less contaminated by the overla!a effect, and it would may be an intrinsic feature of radiation ohvsics.