Variability and spectral variation of 3C 66A

3C 66A was monitored by the BATC (Beijing-Arizona-Taipei-Connecticut) telescope from 2005 to 2008, 1994 observations were obtained on 89 nights. Detailed research and analysis was performed on these observations in this paper. A long term burst occurred in the whole light curve. No intra-day variability was claimed in our campaign by intra-night light curve analysis. Time lag of shorter wavelenth preceding longer wavelength was shown by correlation analysis. The results showed that the optical spectral shape turned flatter when the source brightened, and the spectral variability indicator was bigger on shorter time-scale as determined by the color indices variation analysis.     

The first photometric study of W UMa eclipsing binary OQ Dra

The present study is an analysis of V-band CCD observations of new W UMa contact binary OQ Dra. To carry out the analysis, Primary and secondary minimum were obtained and new epoch was calculated. The computed period of system was 0.33967 day. Light curve analysis was performed using Binary Maker 3 and PHOEBE that uses the latest Wilson–Devinney code. We obtained photometric mass ratio of q_ptm = 0.55.O’Connell effect also was seen in the fitted model. Finally, the best model was achieved by introducing 2 spots on each component.     

The 283 day periodicity in the O-C diagram of β Lyrae

A detailed analysis of an extensive collection of minima of Beta Lyrae was performed. After removing the effect of the orbital period increase, we applied the Fourier analysis to the O-C residuals. The most prominent periodicity is 283 days with amplitude of about 0.05 days. We confirm the period found by Van Hamme, Wilson & Guinan [1995, Astron. J., 110, 1350] from analysis of the photometric light curves of β Lyrae.     

双星γ脉冲星PSR1820-11

通过对γ天文卫星COS-B观测数据的成像分析,我们在近银河中心区域找到一个新的γ射线源.图1为对50—150MeV能区γ射线的成像结果.图1中的“+”号为双星射电脉冲星PSR1820-11的位置,在γ射线成像误差范围内与γ强度峰的位置相符.     

Novel Analysis of Tadpole and Horseshoe Orbits

A simple analysis of tadpole and horseshoe orbits is performed using a new perturbation technique. The first-order results are presented explicitely, extension to any perturbation order is delineated. This revised version was published online in July 2006 with corrections to the Cover Date.     

Frequency shift in Fourier analysis

Error analysis of the frequency determination by conventional Fourier method was performed. Taking into consideration only equidistant data, estimates were obtained on the accuracy of the frequencies deduced by analysing a noise-free signal containing not more than two sinusoidal components with closely spaced frequencies. An important consequence of these results was the empirical distribution function of the frequencies for signals contaminated by noise and containing sufficiently distant frequencies.     

Nonlinear electrostatic drift Kelvin-Helmholtz instability

Nonlinear analysis of electrostatic drift Kelvin-Helmholtz instability is performed. It is shown that the analysis leads to the propagation of the weakly nonlinear dispersive waves and the nonlinear behaviour is governed by the nonlinear Burger's equation.     

BeppoSAX observations of GRS 1915+105.

Results from a BeppoSAX observational campaign on GRS 1915+105, performed in October/November 1996, are presented. The source was observed 10 times (nine 10 ksec snapshots, one 100 ksec long observation). The broad band spectral analysis reveals a complex spectrum, including Compton reflection and an iron emission line, probably originating from a relativistic disc.     

A search for superhumps in the cataclysmic variable SW Sextantis

We present differential photometry of the cataclysmic variable star SW Sextantis. A time series analysis was performed in search of superhumps in the accretion disk of this star, which is the prototype of a class of cataclysmic variables, the SW Sex stars. We find no superhumps, which shows that the presence of superhumps is not a defining feature of the SW Sex stars.     

Period analysis for the peculiar variable FG sagittae

The analysis of the available photoelectric observations covering the interval 1970–1987 was performed. The rapid secular variation of the physical parameters of the star makes the analysis of the whole data set impossible. From the yearly observations (2–3 cycles long) only one period can be determined, the variation of these periods shows a 4–5 year periodicity. The analysis of 2–5 years of observations shows two close frequency components with a nearly constant frequency ratio but with varying amplitudes. The two frequency fits, however, do not describe all the characteristics of the light curve. New photoelectric observations carried out between 1980 and 1987 are also published.     

Complements to Moons'1 Lunar Libration Theory

Analytical complements have been brought to Moons' lunar libration theory concerning tidal effects, direct perturbations due to the Earth's figure, and indirect non periodic perturbations. Comparisons to JPL numerical integrations DE245 and DE403 have been performed and the residuals treated by frequency analysis, allowing the determination of fitted free libration parameters and numerical complements. This revised version was published online in July 2006 with corrections to the Cover Date.     

Analysis of Optical Variations of BL Lac Object AO 0235+164

Historical optical BVRI band data are combined on the BL Lac object AO 0235 + 164. In order to examine the possible existence of lags and correlations between variations in different optical bands from this source, a statistical analysis is performed through the Discrete Correlation Function (DCF) method. Monte Carlo simulations called Flux Redistribution/Random Subset Selection (FR/RSS) are performed to obtain statistically meaningful values for the cross-correlation time lags and their related uncertainties. The analysis confirms that the variations in different optical light curves are strongly correlated, with no or very weak lag within the errors. Long term variability of color indices are also analysed. No color variabilities are found.     

Determining the Characteristics of Lan 30 from Optical Observations

Astronomy Letters - We have performed a model analysis of the optical radiation from the young pre-cataclysmic variable Lan 30 and determined the set of its fundamental characteristics....     

A particle classification system for the PAMELA calorimeter

In this paper we propose a particle classification system for the imaging calorimeter of the PAMELA satellite-borne experiment. The system consist of three main processing phases. First, a segmentation of the whole signal detected by the calorimeter is performed to select a Region of Interest (RoI); this step allows to retain bounded and space invariant portions of data for the following analysis. In the next step, the RoIs are characterized by means of nine discriminating variables, which measure event properties useful for the classification. The third phase (the classification step) relies on two different supervised algorithms, Artificial Neural Networks and Support Vector Machines. The system was tested with a large simulated data set, composed by 40 GeV/c momentum electrons and protons. Moreover, in order to study the classification power of the calorimeter for experimental data, we have also used biased simulated data. A proton contamination in the range 10⁻⁴–10⁻⁵ at an electron efficiency greater than 95% was obtained. The results are adequate for the PAMELA imaging calorimeter and show that the approach to the classification based on soft computing techniques is complementary to the traditional analysis performed using optimized cascade cuts on different variables.     

An elemental abundance analysis of the magnetic chemically peculiar star HR 8216

An elemental abundance analysis of the cool magnetic CP star HR 8216 (= HD204411) was performed using 2.4 Å mm⁻¹ Dominion Astrophysical Observatory Reticon exposures covering  λλ3830–4770  with a typical signal-to-noise ratio of 200 taken with the long camera of the 1.22-m telescope. The spectrograms were measured interactively with the graphics computer program reduce . The fine analysis used an ATLAS9 metal-rich model atmosphere, the predictions of which best-matched the optical region fluxes and the Hγ profile. The anomalies of HR 8216 are primarily an enhancement of many iron peak elements with the rare earths elements much less enhanced than in many similar cool magnetic CP stars. Using the results of the fine analysis the spectrum was synthesized. Comparison with the observed spectrum showed that the agreement is good but did not fully account for all of the observed line spectrum.     

Ionospheric dispersion and Pc 1 pulsations

Dispersion measurements were performed on geomagnetic pulsation data recorded over an Australasian network in a search for evidence of ionospheric dispersion of Pc 1 signals. A method of analysis was adopted in which the slope of emission elements of a selected Pc 1 event are examined individually. It has been found that there are no significant ionospheric dispersion effects for propagation between middle and low latitudes. Magnetospheric propagation paths calculated from dispersion measurements show large variations and are not considered generally reliable.     

Timescale Analysis of Spectral Lags

A technique for timescale analysis of spectral lags performed directly in the time domain is developed. Simulation studies are made to compare the time domain technique with the Fourier frequency analysis for spectral time lags. The time domain technique is applied to studying rapid variabilities of X-ray binaries and γ-ray bursts. The results indicate that in comparison with the Fourier analysis the timescale analysis technique is more powerful for the study of spectral lags in rapid variabilities on short time scales and short duration flaring phenomena.     

Analysis of the Stability of a Planetary System on Cosmogonic Time Scales

Astronomy Letters - We consider the dynamical evolution of planetary systems whose structure is nearly circular and coplanar. The analysis is performed by the Hori–Deprit averaging method...     

Ice Permafrost ‘‘Oases’’ Close to Martian Equator: Planet Neutron Mapping Based on Data of FREND Instrument Onboard TGO Orbiter of Russian-European ExoMars Mission

Astronomy Letters - We present the first results of Mars neutron sounding by FREND instrument onboard ESA’s Trace Gas Orbiter data analysis. Neutron flux mapping is performed with high...     

Phase plane analysis of the commensurable restricted three-body problem

All possible long period motions of the planar circular restricted three-body problem were studied by phase-plane analysis of the disturbing function when a commensurability relation exists. The short period argument was eliminated by an averaging process using an electronic computer. Initial conditions of periodic solutions are determined and the existence of asymmetric ones is proved for certain commensurabilities.The numerical computations performed cover the cases of large eccentricities and the curves of the mean value of the Hamiltonian were studied for the cases which correspond to collision periodic solutions.