Astronomy

Long-term Clock Bias Prediction Based on An ARMA Model
The long-term and reliable prediction of satellite clock bias (SCB) is an important prerequisite for realizing the satellite autonomous navigation and orbit determination. Considering the shortcomings of the quadratic polynomial model (PM) and gray system model (GM) in the long-term prediction of SCB, a new prediction method of SCB based on an ARMA (Auto-Regressive Moving Average) model is prop...


Comparisons and Evaluations of JPL Ephemerides
In the light of the wide applications of a series of ephemerides developed by the Jet Propulsion Laboratory (JPL) of the National Aeronautics and Space Administration (NASA) of the USA to many aspects like the deep-space navigation and interplanetary exploration, it is necessary to make comparisons of their contents, applicable ranges, realizations and maintenances. In view of the fact that the...
Investigation of Thermal Inertia and Surface Properties for Near-earth Asteroid (162173) 1999 JU3
In order to obtain the substantial information about the surface physics and thermal property of the target asteroid (162173) 1999 JU3, which will be visited by Hayabusa 2 in a sample return mission, with the Advanced Thermal Physical Model (ATPM) we estimate the possible thermal inertia distribution over its surface, and infer the major material composition of its surface materials. In additio...


A Statistical Study of the Mass Distribution of Neutron Stars
By reviewing the methods of mass measurements of neutron stars in four different kinds of systems, i.e., the high-mass X-ray binaries (HMXBs), low-mass X-ray binaries (LMXBs), double neutron star systems (DNSs) and neutron star-white dwarf (NS-WD) binary systems, we have collected the orbital parameters of 40 systems. By using the boot-strap method and the Monte-Carlo method, we have rebuilt th...
12CO J=2-1 and J=3-2 Line Observations of Molecular Clouds toward the Directions of 59 EGOs in the Northern Sky
In order to investigate the differences between the molecular clouds which are associated with the massive star forming regions and those which are not, we have performed the single-dish simultaneous observations of 12CO J=2-1 and J=3-2 lines toward a sample of 59 Spitzer Extended Green Objects (EGOs) as the massive star forming regions in the northern sky. Combining our results with the data o...


Luminosity Function of The Galaxy Cluster Abell 85
Using the photometric and spectroscopic data from the NASA/IPAC Extragalactic Database (NED) and the Eighth Data Release of Sloan Digital Sky Survey (SDSS-DR8), we have studied the luminosity function (LF) of the galaxy cluster Abell 85 within the double dynamical radius 2r 200. It is shown that the LF of Abell 85 can be fitted very well with a Schechter function in all the 5 SDSS wavebands, an...
The Long-term Light Variation of BL Lac Object 1ES 1959+650
According to the data of optical observations of the Tuorla Observatory in Finland, using the power spectrum method, DCF (Discrete Correlation Function) method, and Jurkevich method, respectively, we analyzed the periodicity of the long-term light variation of the BL Lac object 1ES 1959+650, and obtained its light period to be P =1.4±0.3 yr. Assuming that the origin of the periodicity is conce...

Light Periodicity Analysis of Blazar Object OJ 287 Based on Empirical Mode Decomposition
Considering the shortages of classical methods in periodicity analysis, the method of empirical mode decomposition (EMD) for processing nonlinear and non-stationary signals is applied to the V-band fluxes of OJ 287 from 1891 to 2010, 10 intrinsic mode functions with different timescales and a residual function are obtained from the light curve. The result shows that there exists a period of 12....
Comparison of Energetic Electron Intensities Outside and Inside the Radiation Belts
The intensities of energetic electrons (~25 – 800 keV) outside and inside Earth's radiation belts are reported using measurements from THEMIS and Van Allen Probes during non-geomagnetic storm periods. Three intervals of current disruption/dipolarization events in August, 2013 were selected for comparison. The following results are obtained. (1) Phase space densities (PSDs) for the equatoria...

Limiting energy spectrum of an electron radiation belt
To determine the Kennel-Petschek limiting particle flux in a planetary radiation belt in a fully relativistic regime, without assuming a pre-determined form for the particle energy distribution, has been a long-standing challenge in space physics. In this paper, for the case of whistler-mode wave-electron interaction, we meet this challenge. The limiting flux is determined by a steady-state mar...
Statistical study of chorus wave distributions in the inner magnetosphere using Ae and solar wind parameters
Energetic electrons within the Earth's radiation belts represent a serious hazard to geostationary satellites. The interactions of electrons with chorus waves play an important role in both the acceleration and loss of radiation belt electrons. The common approach is to present model wave distributions in the inner magnetosphere under different values of geomagnetic activity as expressed by the...

Simulations of the equatorial thermosphere anomaly: Geomagnetic activity modulation
The modulation of geomagnetic activity on the equatorial thermosphere anomaly (ETA) in thermospheric temperature under the high solar activity condition is investigated using the Thermosphere Ionosphere Electrodynamics General Circulation (TIEGCM) simulations. The model simulations during the geomagnetically disturbed interval, when the north-south component of the interplanetary magnetic field...
Fine-scale transient arcs seen in a shock aurora
We report, for the first time, fine-scale transient arcs that emerged successively within the initial 1–2 min evolutionary interval of a postnoon shock aurora on 14 July 2012. Data were acquired from ~2 Hz temporal resolution imaging of dayside aurora with a white light all-sky camera (ASC) at South Pole Station (magnetic latitude = –74.3°, magnetic local time = UT–3.5 h). Just after 180...
Sources of Uncertainty in Ionospheric Modeling: The Neutral Wind
The neutral wind is a critical input parameter for physics-based ionospheric models, affecting both the height of the F-layer and the total electron content. Unfortunately, the currently available models of the thermospheric wind do not seem to represent it very accurately, and this places a serious limitation on the effectiveness of ionospheric modeling and forecasting. We make use of several ...
A solar cycle of upper thermosphere density observations from the EISCAT Svalbard Radar
We exploit a recently-developed technique, based on ion-neutral coupling, which allows estimations of the upper thermospheric neutral density using measurements of ionospheric plasma parameters made by the EISCAT Svalbard Radar (ESR). The technique is applied to a 13-year long data set of measurements for the purpose of studying and quantifying the effect of solar activity on the upper thermosp...