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Geostationary earth orbit satellites have been extensively used for unique high-orbit stationary characteristics. Long-term precise investigation is an important issue in the observation of GEO satellites, since it can provide valuable information on the satellites’ operation state, discrimination and early warning analysis. Ground-based optical-electronic devices play a significant role in the observation. 4-month photometric signature variation of two satellites is presented based on the successive observations using the 1.56-meter telescope of Shanghai Astronomical Observatory (SHAO). It can be concluded that the long-term brightness change mainly results from the sun declination angle and regular orbit maneuver. Moreover, the solar panel offsets of the two satellites are analyzed and found to be approximately 4 degrees. Estimation of photometric accuracy reaches 0.15 mag for the application of CCD drift-scan optical-electronic technique.

High precision astrometry aims at source position determination to a very small fraction of the diffraction image size, in high SNR regime. One of the key limitations to such goal is the optical response variation of the telescope over a sizeable FOV, required to ensure bright reference objects to any selected target. The issue translates into severe calibration constraints, and/or the need for complex telescope and focal plane metrology. We propose an innovative system approach derived from the established TMA telescope concept, extended to achieve high filling factor of an annular field of view around the optical axis of the telescope. The proposed design is a very compact, 1 m class telescope compatible with modern CCD and CMOS detectors (EFL = 15 m). We describe the concept implementation guidelines and the optical performance of the current optical design. The diffraction limited FOV exceeds 1.25 square degrees, and the detector occupies the best 0.25 square degree with 66 devices., 15 pages, 12 figures; Proc. SPIE 11443, Space Telescopes and Instrumentation 2020: Optical, Infrared, and Millimeter Wave

Astrometric Science and Technology Roadmap for Astrophysics (ASTRA) is a bilateral cooperation between China and Italy with the goal of consolidating astrometric measurement concepts and technologies. In particular, the objectives include critical analysis of the Gaia methodology and performance, as well as principle demonstration experiments aimed at future innovative astrometric applications requiring high precision over large angular separations (one to 180 degrees). Such measurement technologies will be the building blocks for future instrumentation focused on the "great questions" of modern cosmology, like General Relativity validity (including Dark Matter and Dark Energy behavior), formation and evolution of structure like proto-galaxies, and planetary systems formation in bio compatibles environments. We describe three principle demonstration tests designed to address some of the potential showstoppers for high astrometric precision experiments. The three tests are focused on the key concepts of multiple fields telescopes, astrometric metrology and very fine sub-pixel precision (goal, 12 pages, 12 figures; SPIE Astronomical Telescopes + Instrumentation, 2020, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation IV

A new generation telescope for objects at Geosynchronous Earth Orbit (GEO) was developed by Shanghai Astronomical Observatory at the end of 2017, it’s called FocusGEO telescope. The goal is to observe nearly all the GEO objects over the observation station near real-time. FocusGEO telescope consists of three refracting telescopes of 18 cm aperture and 22 cm focal length, forming a super-large rectangular field of view(FOV) of 3 × 9.5°×9.5°. Each 15 min FocusGEO telescope scans a strip of sky 112.9°long × 28.3°high, almost fully covers the GEO belt over the station. In early 2018, FocusGEO observations were carried out at the Lijiang Observatory site of Yunnan Observatory, the results show that FocusGEO can observe about 380 GEO objects over the station per night. Its observation completeness is over 90% to GEO objects catalogued by USSTRATCOM. In the case of exposure for 5 s, FocusGEO can observe 15 magnitude GEO objects. The observation precision is about 3″ in azimuth and elevation.

The Astrometric Gravitation Probe mission is a modern version of the 1919 Dyson-Eddington-Davidson experiment, based on a space-borne telescope with a permanent built-in eclipse, provided by a coronagraphic system. The expected improvement on experimental bounds to General Relativity and competing gravitation theories is by at least two orders of magnitude. The measurement principle is reviewed, in particular the principle of Fizeau-like combination of a set of individual inverted coronagraphs simultaneously feeding a common high resolution telescope. Also, the payload has a dual field of view property, in order to support simultaneous observations of stellar fields either very close, or far away, from the Sun, i.e. fields affected by either high or low light bending. We discuss a set of solutions introduced in the optical design to improve on technical feasibility and robustness of the optical performance against perturbations, in particular induced by manufacturing and alignment tolerances, and launch stresses., 12 pages, 8 figures; SPIE Astronomical Telescopes + Instrumentation, Space Telescopes and Instrumentation 2020: Optical, Infrared, and Millimeter Wave

Geosynchronous Earth Orbit (GEO) satellites are widely used because of their unique characteristics of high-orbit and remaining permanently in the same area of the sky. Precise monitoring of GEO satellites can provide a key reference for the judgment of satellite operation status, the capture and identification of targets, and the analysis of collision warning. The observation using ground-based optical telescopes plays an important role in the field of monitoring GEO targets. Different from distant celestial bodies, there is a relative movement between the GEO target and the background reference stars, which makes the conventional observation method limited for long focal length telescopes. CCD drift-scan photoelectric technique is applied on monitoring GEO targets. In the case of parking the telescope, the good round images of the background reference stars and the GEO target at the same sky region can be obtained through the alternating observation of CCD drift-scan mode and CCD stare mode, so as to improve the precision of celestial positioning for the GEO target. Observation experiments of GEO targets were carried out with 1.56-meter telescope of Shanghai Astronomical Observatory. The results show that the application of CCD drift-scan photoelectric technique makes the precision of observing the GEO target reach the level of 0.2″, which gives full play to the advantage of the long focal length of the telescope. The effect of orbit improvement based on multi-pass of observations is obvious and the prediction precision of extrapolating to 72-h is in the order of several arc seconds in azimuth and elevation.

The paper describes observations of fast-moving near-Earth asteroids (NEAs) made with the small ground-based telescopes of National Time Service Center of Chinese Academy of Science (NTSC of CAS) and Research Institute “Mykolaiv Astronomical Observatory” (RI MAO) by the rotating-drift-scan CCD (RDS CCD) technique. This technique is used to obtain the point images of both the studied objects and reference stars. The results of ongoing follow-up observations of NEAs are discussed. The residual differences (O – C) between the observed and calculated positions from JPL ephemeris were generally small for these asteroids. The standard deviations of these differences were typically ±(0.2″ – 0.3″) in both coordinates for objects with apparent velocity which substantially exceed FWHM for the given exposure time. The results of comparative statistics for such observations from the MPC database show that this is a good level of precision for NEAs. Moreover, the telescopes with the RDS CCD technique implemented can observe the NEAs that closely approach the Earth and with enough observations can improve the precision of determining their orbital elements and impact predictions.

For lots of scientific questions about lunar physics deep inside the Moon, in-situ observation on lunar physical libration is one of the most potential ways. In this paper, we propose a brand new optical telescope functioned with simultaneously observing multiple (here there are three) fields of view (FOVs) for in-situ observation of lunar physical libration. The telescope can be placed at any place with any attitude on the Moon and do not require manned install, control or operation. It passively, continuously and simultaneously observe stars in three FOVs along with rotation of the Moon. Libration is to be measured and studied from celestial motion of the directions of three FOVs from image processing. The concept and design of this telescope are firstly introduced in this paper. The principle and feasibility of the method of in-situ observation are also demonstrated. From simulation, precision of the determined lunar physical libration is expected to be several milliarcsecs, about two orders of magnitude better than the current precision of libration by lunar laser ranging observation. Libration data with milliarcsec precision level can play a valuable role in the study of the physics and dynamics of the interior of the Moon. This telescope can also be applied to observe the rotation of other terrestrial planets like Mars.

Gaia data release 2 (DR2) provides the best non-rotating optical frame aligned with the radio frame (ICRF) thanks to the inclusion of about half-million quasars in the five-parameter astrometric solution. We cross-match with Gaia DR2 the quasars from Large Quasar Astrometric Catalogue, Sloan Digital Sky Survey and LAMOST, obtaining 208,743 new sources (denominated as KQCG), and most of them are fainter than G = 19. Given their crucial diagnostic role for characterizing the properties of the celestial reference frame, we aim to probe more accurately the properties of the reference frame at the faintest magnitudes. Combining them with the quasars already identified in DR2, we estimate the moving mean of parallaxes and proper motions. The features of the proper motion are analyzed by means of vectorial spherical harmonics; the scalar field of parallaxes is expanded into spherical harmonics to investigate their spatial correlation, which reveals an angular scale of systematics of ≈18° with a rms amplitude of 13 μas. The global moving mean of the parallaxes and proper motions are calculated. The amplitude of proper motion bias can be up to ∼10 μas yr−1 in some sky regions for both components, and these biases seem to be related to the patterns of the scanning law. The reference frame exhibits a (−6, −5, −5) ± 1 μas yr−1 spin in the northern hemisphere and a spin of (0, +1, +3) ± 1 μas yr−1 in the southern one, which may be caused by the star contamination. The quadrupolar anisotropy of the proper motion filed is analyzed, where a significant quadrupolar signal (the largest component’s amplitude is up to −15 μas yr−1) is found.

The Lunar-based Ultraviolet Telescope (LUT) is an astronomical instrument aboard Chang'e 3, the lunar probe of China's Lunar Exploration Program that successfully landed on the northern part of the Moon's Mare Imbrium (340.4884E, 44.1214N) in late 2013. LUT is charting an ultraviolet map of the plane of the Milky Way and is also providing long-term light variability monitoring for a sample of RR Lyrae stars. However, the principal goal of the computer-controlled landing of the probe was a safe descent to a stable resting-place, and therefore, the precise orientation of LUT was never a priority. For this reason, at least theoretically, touch-down could have occurred anywhere and, for LUT, at any attitude, which would make the pointing and tracking of the wanted celestial objects practically impossible. Moreover, to reduce the data transmission load, the whole frame of every exposure could not be downloaded: only the image data containing the objects can make it to the ground; also, in order to save on electricity, the telescope does not usually track objects, which means that targets' accurate positions and velocities (within the focal plane CCD) are both needed. This paper presents the astrometric solution devised to solve these problems: feasibility is first shown with experiments done from Earth, and then confirmed with actual LUT observations from the Moon's surface.

Aims. The Gaia catalogue brings new opportunities and challenges to high-precision astronomy and astrometry. The precision of data reduction is therefore improved by a large number of reference stars with high-precision positions and proper motions. Numerous precise positions for Triton are obtained from the latest observations using the Gaia catalogue. Furthermore, the new INPOP19a planetary ephemeris, which also fits the observations from the Gaia Data Release 2, has recently become available. In this paper, a new orbit of Triton is calculated using the latest precise charge-coupled device (CCD) observations and the INPOP19a ephemeris. Methods. Triton’s orbital solution is calculated using a numerical integrator, while the orientation of Neptune’s pole in particular is obtained by integrating the simplified Euler’s equations of motion. We determine the orbit of Triton over 170 yr based on 11 040 Earth-based observations made between 1847 and 2016 and on Voyager 2 data. The positions of the Sun and planets are provided by the INPOP19a ephemeris. We compare our results to those from other previous works to check the influences on Triton’s orbit from different planetary ephemerides. Results. A new orbit of Triton is provided here. The root-mean-square of the residuals for the Earth-based CCD absolute observations are 0.102″ in right ascension and 0.142″ in declination. Although most different planetary ephemerides have large differences in Neptune’s position, the orbits of Triton using different planetary ephemerides are still close, under similar dynamical models. The Voyager 2 data add a constraint on Triton’s orbit here.

We present new criteria for selecting HII regions from the Infrared Astronomical Satellite (IRAS) Point Source catalogue (PSC), based on an HII region catalogue derived manually from the all-sky Wide-field Infrared Survey Explorer (WISE). The criteria are used to augment the number of HII region candidates in the Milky Way. The criteria are defined by the linear decision boundary of two samples: IRAS point sources associated with known HII regions, which serve as the HII region sample, and IRAS point sources at high Galactic latitudes, which serve as the non-HII region sample. A machine learning classifier, specifically a support vector machine (SVM), is used to determine the decision boundary. We investigate all combinations of four IRAS bands and suggest that the optimal criterion is log(F$_{\rm 60}$/F$_{\rm 12}$)$\ge$(-0.19$\times$log(F$_{\rm 100}$/F$_{\rm 25}$)+ 1.52), with detections at 60 and 100 micron. This selects 3041 HII region candidates from the IRAS PSC. We find that IRAS HII region candidates show evidence of evolution on the two-colour diagram. Merging the WISE HII catalogue with IRAS HII region candidates, we estimate a lower limit of approximately 10200 for the number of HII regions in the Milky Way., MNRAS, Accepted. 11 pages, 7 figures

A numerical solution to the Earth's precession in a relativistic framework for a long time span is presented here. We obtain the motion of the solar system in the Barycentric Celestial Reference System by numerical integration with a symplectic integrator. Special Newtonian corrections accounting for tidal dissipation are included in the force model. The part representing Earth's rotation is calculated in the Geocentric Celestial Reference System by integrating the post-Newtonian equations of motion published by Klioner et al. All the main relativistic effects are included following Klioner et al. In particular, we consider several relativistic reference systems with corresponding time scales, scaled constants and parameters. Approximate expressions for Earth's precession in the interval +/- 1 Myr around J2000.0 are provided. In the interval +/- 2000 years around J2000.0, the difference compared to the P03 precession theory is only several arcseconds and the results are consistent with other long-term precession theories.

Under the framework of observational campaigns organized by the GAIA Follow Up Network for Solar System Objects, three near Earth asteroids, 367943 Duende, 99942 Apophis and 2013 TV135, were observed with the Lijiang 2.4m telescope administered by Yunnan Observatories. The software package PRISM was used to calibrate the CCD fields and measure the positions of 99942 Apophis and 2013 TV135, and our own software was used for 367943 Duende. A comparison of the results show that the ephemerides of INPOP10a and JPL are consistent for 99942 Apophis and 2013 TV135, however, they are quite inconsistent for 367943 Duende. Moreover, we have found that differences between the mean values in the ephemerides of INPOP10a and JPL are about 72 '' and - 199 '' in right ascension and declination respectively for 367943 Duende. Moreover, the ephemeris published by JPL is reliable in terms of the mean observed-minus-calculated (O - C) residuals in right ascension and declination of about 2.72 '' and 1.49 '' respectively.

We present a study of the three-dimensional structure of the molecular clouds in the Galactic Centre (GC) using CO emission and OH absorption lines. Two CO isotopologue lines, $^{12}$CO ($J$=1$\rightarrow$0) and $^{13}$CO ($J$=1$\rightarrow$0), and four OH ground-state transitions, surveyed by the Southern Parkes Large-Area Survey in Hydroxyl (SPLASH), contribute to this study. We develop a novel method to calculate the OH column density, excitation temperature, and optical depth precisely using all four OH lines, and we employ it to derive a three-dimensional model for the distribution of molecular clouds in the GC for six slices in Galactic latitude. The angular resolution of the data is 15.5 arcmin, which at the distance of the GC (8.34 kpc) is equivalent to 38 pc. We find that the total mass of OH in the GC is in the range 2400-5100 Solar mass . The face-on view at a Galactic latitude of b = 0{\deg} displays a bar-like structure with an inclination angle of 67.5 $\pm$ 2.1{\deg} with respect to the line of sight. No ring-like structure in the GC is evident in our data, likely due to the low spatial resolution of the CO and OH maps., Comment: Accepted for publication in MNRAS, 15 pages, 12 figures

A model which includes the relativistic effect is derived that can be applied to space very long baseline interferometry (SVLBI) while taking observations of sources at infinite distance. In SVLBI, where one station is on a spacecraft, the length of the baseline and the orbiting station's maximum speed in an elliptical orbit around the Earth is much larger than the ground-based VLBI, which leads to a larger delay and higher delay rate. The delay models inside VLBI correlators are usually expressed as fifth-order polynomials during a limited time interval, which are evaluated by firmware in the correlator and track delays in the interferometer over the limited time interval. The higher SVLBI delay rate requires more accurate polynomial fitting and evaluation, as well as more frequent model updates.

We report the distances of molecular clouds at high Galactic latitudes (|b|>10$^\circ$) derived from parallax and G band extinction (A$_{\rm G}$) measurements in the second Gaia data release, Gaia DR2. Aided by Bayesian analyses, we determined distances by identifying the breakpoint in the extinction A$_{\rm G}$ towards molecular clouds and using the extinction A$_{\rm G}$ of Gaia stars around molecular clouds to confirm the breakpoint. We use nearby star-forming regions, such as Orion, Taurus, Cepheus, and Perseus, whose distances are well-known to examine the reliability of our method. By comparing with previous results, we found that the molecular cloud distances derived from this method are reliable. The systematic error in the distances is approximately 5%. In total, 52 molecular clouds have their distances well determined, most of which are at high Galactic latitudes, and we provide reliable distances for 13 molecular clouds for the first time., Accepted by A&A. 13 pages, 9 figures

Context. Quasars are spatially stationary, and they are essential objects in astrometry when defining reference frames. However, the census of quasars is far from complete. Mid-infared colors can be used to find quasar candidates because AGNs show a peculiar appearance in mid-infrared color, but these methods are incapable of separating quasars from AGNs. Aims. The aim of our study is to use astrometric and mid-infrared methods to select quasars and get a reliable quasar candidates catalog. Methods. We used a near-zero proper motion criterion in conjuction with WISE (all-sky Wide-field Infrared Survey Explorer) [W1-W2] color to select quasar candidates. The [W1-W2] color criterion is defined by the linear boundary of two samples: LAMOST DR5 quasars, which serve as the quasar sample, and LAMOST DR5 stars and galaxies, which serve as the non-quasar sample. The contamination and completeness are evaluated. Results. We present a catalog of 662 753 quasar candidates, with a completeness of about 75% and a reliability of 77.2%., 7 pages, 7 figures, accepted by A&A

We report the internal proper motions of 12 GHz methanol masers in massive star-forming region G35.20–0.74 observed with the Very Long Baseline Array (VLBA) at four epochs spanning about 1.5 yr. Two groups of maser features were detected, groups A and B, and the latter that had a V-shaped spatial distribution is likely tracing the north outflow in G35.20–0.74. We present a three-dimensional model for the kinematics of these masers, by assuming the interstellar medium was blown by the stellar wind from the driving source (G35.2N) of the outflow. Adopting a position angle of ~ 81° for the main axis of the outflow from previous studies, we estimate an inclination of 35° ± 5.5°, a velocity of 8.1 ± 0.7 km s−1 for the stellar wind along the main axis and an expansion speed gradient of 0.05 ± 0.016 km s−1 AU−1. From the model, we derive the age of the north outflow in G35.20–0.74 to be ~ 1.6 × 104 yr.

The mutual eclipse of S4 Dione by S3 Tethys (Dec 23, 2009) and mutual occultation of S3 Tethys by S4 Dione (Apr 24, 2010) were observed at Yunnan Observatory during the international campaign in 2009-2010. The aim of this paper is to calculate the astrometric data of the involved Saturnian satellites during the mutual events, using a same dynamical model as proposed by Assafin et al. (2009) for the mutual occultation and a same one as proposed by Zhang and Liu (2011) for the mutual eclipse, and taking the scattering properties of the Saturnian satellites surfaces into account. Compared with the theory TASS 1.7 (Vienne and Duriez, 1995), the O-C(x) and O-C(y) are 10.1 mas, 3.4 mas for the mutual eclipse S4 by S3 and 28.4 mas, -1.3 mas for the mutual occultation S3 by S4, and with respect to the theory by Lainey et al. (2011), the results are 1.0 mas, -5.0 mas and -0.2 mas, 2.5 mas respectively. (C) 2012 Elsevier Ltd. All rights reserved.

We investigated the physical properties of molecular clouds and star formation processes around infrared bubbles which are essentially expanding HII regions. We performed observations of 13 galactic infrared bubble fields containing 18 bubbles. Five molecular lines, 12CO (J=1-0), 13CO (J=1-0), C18O(J=1-0), HCN (J=1-0), and HCO+ (J=1-0), were observed, and several publicly available surveys, GLIMPSE, MIPSGAL, ATLASGAL, BGPS, VGPS, MAGPIS, and NVSS, were used for comparison. We find that these bubbles are generally connected with molecular clouds, most of which are giant. Several bubble regions display velocity gradients and broad shifted profiles, which could be due to the expansion of bubbles. The masses of molecular clouds within bubbles range from 100 to 19,000 solar mass, and their dynamic ages are about 0.3-3.7 Myr, which takes into account the internal turbulence pressure of surrounding molecular clouds. Clumps are found in the vicinity of all 18 bubbles, and molecular clouds near four of these bubbles with larger angular sizes show shell-like morphologies, indicating that either collect-and-collapse or radiation-driven implosion processes may have occurred. Due to the contamination of adjacent molecular clouds, only six bubble regions are appropriate to search for outflows, and we find that four of them have outflow activities. Three bubbles display ultra-compact HII regions at their borders, and one of them is probably responsible for its outflow. In total, only six bubbles show star formation activities in the vicinity, and we suggest that star formation processes might have been triggered., Comment: 55 Pages, 32 figures. Accepted for publication in AJ

The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST, also called the Guo Shou Jing Telescope) is a special reflecting Schmidt telescope. LAMOST's special design allows both a large aperture (effective aperture of 3.6 m–4.9 m) and a wide field of view (FOV) (5°). It has an innovative active reflecting Schmidt configuration which continuously changes the mirror's surface that adjusts during the observation process and combines thin deformable mirror active optics with segmented active optics. Its primary mirror (6.67 m × 6.05 m) and active Schmidt mirror (5.74m × 4.40m) are both segmented, and composed of 37 and 24 hexagonal sub-mirrors respectively. By using a parallel controllable fiber positioning technique, the focal surface of 1.75 m in diameter can accommodate 4000 optical fibers. Also, LAMOST has 16 spectrographs with 32 CCD cameras. LAMOST will be the telescope with the highest rate of spectral acquisition. As a national large scientific project, the LAMOST project was formally proposed in 1996, and approved by the Chinese government in 1997. The construction started in 2001, was completed in 2008 and passed the official acceptance in June 2009. The LAMOST pilot survey was started in October 2011 and the spectroscopic survey will launch in September 2012. Up to now, LAMOST has released more than 480000 spectra of objects. LAMOST will make an important contribution to the study of the large-scale structure of the Universe, structure and evolution of the Galaxy, and cross-identification of multi-waveband properties in celestial objects.

This paper describes the data release of the LAMOST pilot survey, which includes data reduction, calibration, spectral analysis, data products and data access. The accuracy of the released data and the information about the FITS headers of spectra are also introduced. The released data set includes 319 000 spectra and a catalog of these objects.

A Basic Angle (BA) of 106.5° separates the view directions of Gaia's two fields of view (FoV). A precise determination of the BA variations (BAV) is essential to guarantee a correct reconstruction of the global astrometric sphere, as residual systematic errors would result in, e.g., a bias in the parallaxes of the final Gaia catalog. The Basic Angle Monitoring (BAM) device, which provides a reliable and accurate estimation of BAV, shows that there exists a ~1 mas amplitude, 6-h period BA oscillation. It's essential to verify to what extent this signal is caused by real BAV, or is at least in part an effect of the BAM device itself. Here, we propose an astrometric on-sky approach to re-determine the 6-h periodic BAV. The results of this experiment, which treated a full day (17 Oct 2016) of Gaia astrometric data, recover a value for the 6-h oscillation of 1.856±0.857 mas. This is consistent, within the errors, with the BAM finding for that day.

In recent years, many new CCD observations of Phoebe, the ninth Saturnian satellite, were published. In this paper, we have used all the observations of Phoebe available until 2009 to update Phoebe's orbit. These observations represent a total number of 2994 positions, spread over a time-interval of 105 years, from 1904 to 2009. The accuracy of the updated orbit of Phoebe presented here has been improved to about 0.1 arcsec as it has been fitted to a large number of new high-accuracy observations. However, the accuracy of the orbit remains limited by the accuracy of the observations. Moreover, we have shown that the new orbit is in quite good agreement with the very reliable JPL ephemeris, within less than 20 mas.

Astrometric observations of Phoebe, the faint ninth satellite of Saturn, with a visual magnitude of 16.5, were performed during four successive oppositions in 2005, 2006, 2007 and 2008. A total of 1173 new observed positions of Phoebe, representing more than 50 per cent of the observational data now available, were obtained during 30 nights of observation involving six missions and three telescopes. A comparison of our observed positions with the JPL Phoebe ephemeris shows the high quality of our observations, which have an accuracy of about 100 mas. Moreover, our observations appear to be consistent with this ephemeris within only about 50 mas.

Because of the influence of atmospheric refraction the astronomical observations of the objects with the angles of elevation below 15° are generally avoided, but for the sake of the complete theoretical research the atmospheric refraction under the condition of lower angles of elevation is still worthy to be analyzed and explored. Especially for some engineering applications the objects with low angles of elevation must be observed sometimes. A new idea for determining atmospheric refraction by utilizing the differential method is proposed. A series of observations of the starry sky at different heights are carried out and by starting from the zenith with a telescope with larger field of view, the derivatives of various orders of atmospheric refraction function at different zenith distances are calculated and finally the actually observed values of atmospheric refraction can be found via numerical integration. The method does not depend upon the strict local parameters and complex precise observational instrumentation, and the observational principle is relatively simple. By the end of 2007 a simply constructed telescope with a larger field of view at Xinglong Observing Station was employed to carry out trial observations. The values of atmospheric refraction at the true zenith distances of 44.8° to 87.5° were obtained from the practical observations based on the differential method, and the feasibility of the method of differential measurement of atmospheric refraction was preliminarily justified. Being limited by the observational conditions, the accuracy of the observed result was limited, the maximal accidental error was about 6” and there existed certain systematic errors. The value of the difference between the result obtained at the zenith distance of 84° and that given in the Pulkovo atmospheric refraction table was about 15”. How to eliminate the cumulative error introduced due to the integration model error is the key problem which needs to be solved in future.

In this paper, we present 112 new CCD astrometric positions of Nereid, the second and faint satellite of Neptune (mv � 19). We observed this small satellite in the 2006–2007 period with the 1 and 2.16-m telescopes of Xinglong Station near Beijing, both equipped with large CCD detectors of 1340 × 1300 and 2080 × 2048 pixels, respectively. The high density and highly accurate star catalogue UCAC2 was used in the reduction so that a classical astrometric calibration method was applied. We have shown that our observations of Nereid appear to be of equal or higher precision (σ � 0.2 arcsec) than most of the recent CCD ones.

Present accuracy of satellite laser ranging is at the millimeter level. The current time-delay equation of satellite laser ranging given by International Earth Rotation and Reference Systems Service is in agreement with this accuracy. Prospectively, the accuracy of satellite laser ranging will be improved to sub-millimeter in the future (Pearlman et al. 2007). In this paper, for theoretical interest and applications in future satellite-laser-ranging data processing, we develop a relativistic time-delay model for satellite laser ranging by the time-transfer-function method, and investigate all possible relativistic effects on the light propagation between a station and a satellite. The accuracy of our model arrives at the micrometer ( ${\sim}0.01~\mbox{ps}$ ) level. For achieving such accuracy, only the quadrupole moment of the Earth needs to be taken into account compared with the existing model. This micrometer-level model should be useful in tests of the gravitation theory, high accuracy orbital determination of satellites and geodesy in the future.

We present a new catalog of absolute proper motions and updated positions derived from the same Space Telescope Science Institute digitized Schmidt survey plates utilized for the construction of Guide Star Catalog II. As special attention was devoted to the absolutization process and the removal of position, magnitude, and color dependent systematic errors through the use of both stars and galaxies, this release is solely based on plate data outside the galactic plane, i.e., vertical bar b vertical bar >= 27 degrees. The resulting global zero point error is less than 0.6 mas yr(-1), and the precision is better than 4.0 mas yr(-1) for objects brighter than R-F = 18.5, rising to 9.0 mas yr(-1) for objects with magnitudes in the range 18.5 < R-F < 20.0. The catalog covers 22,525 square degrees and lists 100,774,153 objects to the limiting magnitude of R-F similar to 20.8. Alignment with the International Celestial Reference System was made using 1288 objects common to the second realization of the International Celestial Reference Frame (ICRF2) at radio wavelengths. As a result, the coordinate axes realized by our astrometric data are believed to be aligned with the extragalactic radio frame to within +/- 0.2 mas at the reference epoch J2000.0. This makes our compilation one of the deepest and densest ICRF-registered astrometric catalogs outside the galactic plane. Although the Gaia mission is poised to set the new standard in catalog astronomy and will in many ways supersede this catalog, the methods and procedures reported here will prove useful to remove astrometric magnitude-and color-dependent systematic errors from the next generation of ground-based surveys reaching significantly deeper than the Gaia catalog.

The Large sky Area Multi-Object Spectroscopic Telescope (LAMOST) General Survey is a spectroscopic survey that will eventually cover approximately half of the celestial sphere and collect 10 million spectra of stars, galaxies and QSOs. Objects both in the pilot survey and the first year general survey are included in the LAMOST First Data Release (DR1). The pilot survey started in October 2011 and ended in June 2012, and the data have been released to the public as the LAMOST Pilot Data Release in August 2012. The general survey started in September 2012, and completed its first year of operation in June 2013. The LAMOST DR1 includes a total of 1202 plates containing 2,955,336 spectra, of which 1,790,879 spectra have observed signal-to-noise S/N >10. All data with S/N>2 are formally released as LAMOST DR1 under the LAMOST data policy. This data release contains a total of 2,204,696 spectra, of which 1,944,329 are stellar spectra, 12,082 are galaxy spectra and 5,017 are quasars. The DR1 includes not only spectra, but also three stellar catalogues with measured parameters: AFGK-type stars with high quality spectra (1,061,918 entries), A-type stars (100,073 entries), and M stars (121,522 entries). This paper introduces the survey design, the observational and instrumental limitations, data reduction and analysis, and some caveats. Description of the FITS structure of spectral files and parameter catalogues is also provided., 39 pages, 13 figures

For the sake of complete theoretical research of atmospheric refraction, the atmospheric refraction under the condition of lower angles of elevation is still worthy to be analyzed and explored. In some engineering applications, the objects with larger zenith distance must be observed sometimes. Carrying out observational research of the atmospheric refraction at lower angles of elevation has an important significance. It has been considered difficult to measure the atmospheric refraction at lower angles of elevation. A new idea for determining atmospheric refraction by utilizing differential measurement with double fields of view is proposed. Taking the observational principle of HIPPARCOS satellite as a reference, a schematic prototype with double fields of view was developed. In August of 2013, experimental observations were carried out and the atmospheric refractions at lower angles of elevation can be obtained by the schematic prototype. The measured value of the atmospheric refraction at the zenith distance of 78.8 degree is $240.23"\pm0.27"$, and the feasibility of differential measurement of atmospheric refraction with double fields of view was justified. The limitations of the schematic prototype such as inadequate ability of gathering light, lack of accurate meteorological data recording and lower automatic level of observation and data processing were also pointed out, which need to be improved in subsequent work., Comment: 10 pages, 6 figures

Context. In 2009, the Sun and the Earth passed through the equatorial plane of Jupiter and therefore the orbital planes of its main satellites. It was the equinox on Jupiter. This occurrence made mutual occultations and eclipses between the satellites possible. Experience has shown that the observations of such events provide accurate astrometric data able to bring new information on the dynamics of the Galilean satellites. Observations are made under the form of photometric measurements, but need to be made through the organization of a worldwide observation campaign maximizing the number and the quality of the data obtained. Aims. This work focuses on processing the complete database of photometric observations of the mutual occultations and eclipses of the Galilean satellites of Jupiter made during the international campaign in 2009. The final goal is to derive new accurate astrometric data. Methods. We used an accurate photometric model of mutual events adequate with the accuracy of the observation. Our original method was applied to derive astrometric data from photometric observations of mutual occultations and eclipses of the Galilean satellites of Jupiter. Results. We processed the 457 lightcurves obtained during the international campaign of photometric observations of the Galilean satellites of Jupiter in 2009. Compared with the theory, for successful observations, the r.m.s. of O-C residuals are equal to 45.8 mas and 81.1 mas in right ascension and declination, respectively; the mean O-C residuals are equal to -2 mas and -9 mas in right ascension and declination, respectively, for mutual occultations; and -6 mas and +1 mas in right ascension and declination, respectively, for mutual eclipses. © ESO, 2014. Arlot J.-E. 1 Emelyanov N. 2 1 Varfolomeev M. I. 2 Amossé A. 3 Arena C. 4 Assafin M. 40 Barbieri L. 5 Bolzoni S. 6 Bragas-Ribas F. 54 Camargo J. I. B. 54 Casarramona F. 8 Casas R. 37 Christou A. 9 Colas F. 1 Collard A. 3 Combe S. 10 Constantinescu M. 11 Dangl G. 12 De Cat P. 34 Degenhardt S. 13 Delcroix M. 14 Dias-Oliveira A. 54 Dourneau G. 15 57 Douvris A. 16 Druon C. 3 Ellington C. K. 17 Estraviz G. 8 Farissier P. 10 Farmakopoulos A. 16 Garlitz J. 18 Gault D. 19 George T. 20 Gorda S. Yu. 42 Grismore J. 21 Guo D. F. 22 Herald D. 56 Ida M. 23 Ishida M. 23 Ivanov A. V. 24 Klemt B. 7 Koshkin N. 25 Le Campion J. F. 15 57 Liakos A. 26 Liao S. L. 27 Li S. N. 27 Loader B. 28 Lopresti C. 29 Lo Savio E. 4 Marchini A. 30 Marino G. 4 Masi G. 53 Massallé A. 8 Maulella R. 29 McFarland J. 9 Miyashita K. 32 Napoli C. 4 Noyelles B. 33 1 3 Pauwels T. 34 Pavlov H. 35 Peng Q. Y. 36 Perelló C. 8 Priban V. 38 Prost J. 39 Razemon S. 3 Rousselle J. P. 3 ⋆ Rovira J. 8 Ruisi R. 41 Ruocco N. 31 Salvaggio F. 4 Sbarufatti G. 43 Shakun L. 25 Scheck A. 44 Sciuto C. 4 da Silva Neto D. N. 55 V Sinyaeva N. 45 Sofia A. 4 Sonka A. 11 Talbot J. 46 Tang Z. H. 27 Tejfel V. G. 45 Thuillot W. 1 Tigani K. 16 Timerson B. 47 Tontodonati E. 48 Tsamis V. 16 Unwin M. 49 Venable R. 50 Vieira-Martins R. 54 1 40 Vilar J. 51 Vingerhoets P. 34 Watanabe H. 52 Yin H. X. 22 Yu Y. 27 Zambelli R. 29 1 Institut de mécanique céleste et de calcul des éphémérides-Observatoire de Paris, UMR 8028 CNRS, UPMC, USTL , 77 avenue Denfert-Rochereau , 75014 Paris , France 2 Sternberg Astronomical Institute, Lomonosov Moscow State University , 119991 Moscow , Russia 3 Association Jonckheere-Les Amis de l’Observatoire de Lille, 1 Impasse de l’Observatoire , 59000 Lille , France 4 Gruppo Astrofili Catanesi , 95128 Catania , Italy 5 Associazione Astrofili Bolognesi , 95128 Bologna , Italy 6 viale L.Pirandello, 26 , 21052 Busto Arsizio (VA) , Italy 7 Im Erlenhof 2a , 51429 Bergisch Gladbach , Germany 8 Agrupació Astronómica de Sabadell, Carrer Prat de la Riba, s/n, 08206 Sabadell , Catalonia , Spain 9 Armagh Observatory , College Hill , Armagh BT61 9DG , UK 10 CALA, Place de la nation , 69120 Vaulx-en-Velin , France 11 Observatorul Astronomic Amiral Vasile Urseanu , no.21, Lascar Catargiu Boulevard , 71111 Bucharest , Romania 12 Nonndorf 12 , 3830 , Austria 13 2112 Maple Leaf Trail , Columbia , TN , 38401 , USA 14 2 rue de l’Ardèche , 31170 Tournefeuille , France 15 Univ. Bordeaux, LAB, UMR 5804 , 33270 Floirac , France 16 Astronomical Union of Sparta , 23100 Sparta , Greece 17 Plantation, FL , USA 18 1155 Hartford St Elgin , Oregon 97827 , USA 19 22 Booker Road , Hawkesbury Heights NSW 2777 , Australia 20 136 Rio Senda , Umatilla , Oregon 97882 , USA 21 Bartlesville , Oklahoma , USA 22 Shandong University at Weihai , 264209 Weihai , PR China 23 1-4-17, Okino, Higashi-Ohmi , 527-0034 Shiga , Japan 24 Central Astronomical Observatory of the Russian Academy of Sciences , St. Petersburg , Pulkovo , Russia 25 Astronomical observatory of Odessa University , Marazlievskaya st. 1-B , Odessa , Ukraine 26 Department of Astrophysics, Astronomy and Mechanics, University of Athens , 15784 Zografos , Athens , Greece 27 Shanghai Astronomical Observatory, Chinese Academy of Sciences , 200030 Shanghai , PR China 28 14 Craigieburn Street , 7510 Darfield , New Zealand 29 Istituto Spezzino Ricerche Astronomiche , 19125 La Spezia , Italy 30 Astronomical Observatory University of Siena , 53100 Siena , Italy 31 Astrocampania , 80063 Piano di Sorrento , Italy 32 4368-1, Akashina-Nanaki, Azumino, 399-7104 Nagano , Japan 33 University of Namur , NAmur Center for CompleX SYStems (naXys), Rempart de la Vierge 8 , 5000 Namur , Belgium 34 Koninklijke Sterrenwacht van België, Ringlaan 3 , 1180 Brussels , Belgium 35 45/192 Vimiera Rd , Marsfield , NSW 2122 , Australia 36 Department of computer Science, Jinan University , 510632 Guangzhou , PR China 37 Institut de Ciéncies de l’Espai (IEEC-CSIC), Campus UAB, Facultat de Ciéncies , Torre C5 parell 2n pis, 08193 Bellaterra , Catalonia , Spain 38 Observatory and Planetarium Praha , Kralovska obora 233 170 21 Praha 7 , Czech Republic 39 26 impasse des Forsythias , 06560 Valbonne , France 40 Observatório do Valongo/UFRJ , Ladeira Pedro Antonio 43, RJ 23. 070-200 Rio de Janeiro , Brazil 41 Organizzazione Ricerche e Studi di Astronomia , Palermo , Italy 42 Kourovskaya observatory of the Ural Federal University , Prospect Lenina 51 , 620000 Ecaterinbourg , Russia 43 Gruppo Astrofili di Piacenza , Italy 44 Scaggsville , Maryland , USA 45 Fessenkov Astrophysical Institute , Alma-Ata , Kazakhstan 46 RASNZ Occultation Section, 3 Hughes Street , Waikanae Beach , New Zealand 47 Newark , New York , USA 48 Associazione Iblea Divulgazione Astronomica , 497100 Ragusa , Italy 49 9 Payling Lane, 8052 Christchurch , Christchurch , New Zealand 50 PO Box 117 , Chester , GA 31012 , USA 51 8 rue des Ormes , 67450 Mundolsheim , France 52 281, Kasadashinden, Inabe , Mie , 511-0205 , Japan 53 Virtual Telescope Project , Via Madonna de Loco 47 , 03023 Ceccano (FR) , Italy 54 Observatorio Nacional/MCTI , R. General Jose Cristino 77, RJ 20. 921-400 Rio de Janeiro , Brazil 55 Centro Universitário Estadual da Zona Oeste , Av. Manuel Caldeira de Alvarenga 1203, RJ 23. 070-200 Rio de Janeiro , Brazil 56 3 Lupin Pl , Murrumbateman , NSW 2582 , Australia 57 CNRS, LAB, UMR 5804 , 33270 Floirac , France ⋆ J. P. Rousselle died in 2009. e-mail: Jean-Eudes.Arlot@imcce.fr 09 12 2014 09 12 2014 12 2014 572 aa/2014/12 A120 20 3 2014 15 5 2014 © ESO, 2014 2014 ESO Context. In 2009, the Sun and the Earth passed through the equatorial plane of Jupiter and therefore the orbital planes of its main satellites. It was the equinox on Jupiter. This occurrence made mutual occultations and eclipses between the satellites possible. Experience has shown that the observations of such events provide accurate astrometric data able to bring new information on the dynamics of the Galilean satellites. Observations are made under the form of photometric measurements, but need to be made through the organization of a worldwide observation campaign maximizing the number and the quality of the data obtained. Aims. This work focuses on processing the complete database of photometric observations of the mutual occultations and eclipses of the Galilean satellites of Jupiter made during the international campaign in 2009. The final goal is to derive new accurate astrometric data. Methods. We used an accurate photometric model of mutual events adequate with the accuracy of the observation. Our original method was applied to derive astrometric data from photometric observations of mutual occultations and eclipses of the Galilean satellites of Jupiter. Results. We processed the 457 lightcurves obtained during the international campaign of photometric observations of the Galilean satellites of Jupiter in 2009. Compared with the theory, for successful observations, the r.m.s. of O–C residuals are equal to 45.8 mas and 81.1 mas in right ascension and declination, respectively; the mean O–C residuals are equal to –2 mas and –9 mas in right ascension and declination, respectively, for mutual occultations; and –6 mas and +1 mas in right ascension and declination, respectively, for mutual eclipses. astronomical databases: miscellaneous planets and satellites: general occultations eclipses ephemerides idline A&A 572, A120 (2014) cover_date December 2014 first_month 12 last_month 12 first_year 2014 last_year 2014 This work was supported by the Russian Foundation for Basic Research (project no. 12-02-00294), by The European contract ESPaCE (FP7-grant agreement 263466), by the Scientific Council of Paris Observatory, by the CNRS PICS 3840 France-Russia, by the Programme National de Planétologie (CNES and CNRS) and by the National Science Foundation of China (Grant No 11273014) and the Fundamental Research Funds for the Central Universities.

Most of the discovered exoplanets are close to our sun. Usually their host star is with large proper motions, which is an important parameter for exoplanet searching. The first version of absolute proper motions catalog achieved based on Digitized Sky Survey Schmidt plate where outside the galactic plane |b|≥27° is presented, resulting in a zero point error less than ± 0.3 mas/yr, and the overall accuracy better than ± 4.5 mas/yr for objects brighter than RF=18.5, and ranging from 4.5 to 9.0 mas/yr for objects with magnitude 18.5

In this paper optical positions relative to UCAC1 for 22 counterparts of extragalactic radio sources in the southern hemisphere are presented. The internal accuracy of the positions is of the order of 0."060. With the help of astrometric calibration regions, choices of the centering method and the width of the subraster used for object centering are given based on the detailed analysis of the results of centers of stellar images in the CCD on the 1 m telescope at Yunnan Astronomical Observatory, and the choice of the suitable model for the reduction of CCD is also recommended. A comparison of our results with those of other authors is made.

Before CCD detectors were widely employed in observational astronomy, the main method of detection was the use of glass astrophotographic plates. Astronomical plates have been used to record information on the position and activity of celestial bodies for more than 100 years. There are about 30 000 astronomical plates in China, and the digitization of astronomical plates is of great significance for permanent preservation and to make full use of these valuable observation data. A digitizer with high precision and high measuring speed is a key piece of equipment for carrying out the task of digitizing these astronomical plates. A digitizer for glass astrophotographic plates was developed jointly by Shanghai Astronomical Observatory and Nishimura Co., Ltd of Japan. The digitizer’s hardware was manufactured by Nishimura Co., Ltd, and the performance test, error corrections as well as image processing of the digitizer were carried out by Shanghai Astronomical Observatory. The main structure and working mode of the digitizer are introduced in this paper. A performance test shows that brightness uniformity of illumination within the measuring area is better than 0.15%, the repeatability of digitized positions is better than 0.2 μm and the repeatability of digitized brightness is better than 0.01 instrumental magnitude. The systematic factors affecting digitized positions, such as lens distortion, the actual optical resolution, non-linearity of guide rails, non-uniformity of linear motors in the mobile platform, deviation of the image mosaic, and non-orthogonality between the direction of scanning and camera linear array, are calibrated and evaluated. Based on an astronomical plate with a size of 300 mm × 300 mm, which was digitized at different angles, the conversion residuals of positions of common stars on different images were investigated. The results show that the standard deviations of the residuals are better than 0.9 μm and the residual distribution is almost random, which demonstrates the digitizer has a higher precision for digitization.

The guarantee is an important content of bank credit guarantee system and banks hold large amounts of guarantee assets lack of liquidity. Along with the increasingly serious international economic and financial environment, the financial institutions are faced with hard constraints of liquidity. It is necessary to create the liquidity and revitalize the guarantee asset in the case of lack of liquidity for domestic and international financial institutions.Now the asset securitization research mainly focus on the assets with long-term and high risk,few papper researches guarantee assets with short-term and low risk.Based on this,the paper will research the pricing of guarantee securitization.Because of autocorrelation and ARCH effects of financial time series, the AR(1)-AR(9)-AR(22)-T-EGARCH(1,1) Vasicek model is built to solve the parameters of dynamic interest rate model and the Monte Carlo simulation is used to solve the pricing of guarantee-backed securities in this paper. The research shows that the pricing of the guarantee-backed securities has the characteristics of path-dependent, so lots of simulations are needed to be made to reduce the errors; And because of the shorter term of guarantee assets, financial institutions should make great efforts to develop guarantee business to fill and replace the assets of the guarantee asset pool and maintain the stability of cash flow. The research not only extends the theory of asset securitization pricing, but also has important practice significance on the implementation of the guarantee securitization for commercial banks and other financial institutions.

In this paper, image restoration is presented as a way to remove the influence of tracking error in astrometric CCD images, based on the characteristics of spatially invariant tracking error within a CCD frame. The direct deconvolution method was used in the process of image restoration. The results of reduction using practical data show improved precision in the images of star centers, including those of closely spaced stars. In particular, close binaries can be separated easily after image restoration.

Using the ACT reference catalogue as preliminary reference we have reduced 31 exposures on 15 plates in two areas taken with the 40-cm refractor of our Observatory. Using the central overlapping technique and an iterative procedure we have derived high-precision positions and proper motions for 54 stars, including 16 Hipparcos stars. For the latter, the mean standard errors, in right ascension and declination, are 0.70 and 0.59 mas/yr in proper motion, and 10.5 and 7.5 mas in position.

The polynomial-fit method is applied to remove the uneven background of a satellite when it is near a bright primary object. Detailed analysis of this method is given. Some useful conclusions are drawn from the results of simulated data.

To make GSC-II more accurate and useful, it is necessary to re-calibrate GSC-II when a better reference catalogue (UCAC2) is available. With UCAC2 as the reference, preliminary re-calibration of some sample plates from GSC2.3 were carried out with different methods, such as Global, Mask and Filter. The results indicate that a 7th-order polynomial is sufficient to account for the influence of Schmidt plate deformation on the measured coordinates of stars. The magnitude equation can be eliminated after correcting for a common magnitude equation. The RMS of the re-calibrated data is around ±0.2~0.3 arcsec.

We present new quasars discovered in the vicinity of the Andromeda and Triangulum galaxies with the LAMOST during the 2010 and 2011 observational seasons. Quasar candidates are selected based on the available SDSS, KPNO 4 m telescope, XSTPS optical, and WISE near infrared photometric data. We present 509 new quasars discovered in a stripe of ~135 sq. deg from M31 to M33 along the Giant Stellar Stream in the 2011 pilot survey datasets, and also 17 new quasars discovered in an area of ~100 sq. deg that covers the central region and the southeastern halo of M31 in the 2010 commissioning datasets. These 526 new quasars have i magnitudes ranging from 15.5 to 20.0, redshifts from 0.1 to 3.2. They represent a significant increase of the number of identified quasars in the vicinity of M31 and M33. There are now 26, 62 and 139 known quasars in this region of the sky with i magnitudes brighter than 17.0, 17.5 and 18.0 respectively, of which 5, 20 and 75 are newly-discovered. These bright quasars provide an invaluable collection with which to probe the kinematics and chemistry of the ISM/IGM in the Local Group of galaxies. A total of 93 quasars are now known with locations within 2.5 deg of M31, of which 73 are newly discovered. Tens of quasars are now known to be located behind the Giant Stellar Stream, and hundreds behind the extended halo and its associated substructures of M31. The much enlarged sample of known quasars in the vicinity of M31 and M33 can potentially be utilized to construct a perfect astrometric reference frame to measure the minute PMs of M31 and M33, along with the PMs of substructures associated with the Local Group of galaxies. Those PMs are some of the most fundamental properties of the Local Group., 26 pages, 6 figures, AJ accepted