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Inversion of FeO and TiO 2 by passive microwave radiometer not only provide support for high-precision quantitative inversion of lunar surface material component by optical remote sensing but also explore resources among the deep lunar regolith better. Using CE-2's passive microwave data, the daytime microwave map of the Moon is calculated based on the hour angle. The lunar regolith radioactive transfer model, integrated with a temperature model and the lunar regolith thickness model, has been established in this paper. On the basis of aforementioned models, the imaginary part of dielectric constant in the whole lunar was numerically simulated. Thus the FeO+TiO 2 content of the global lunar regolith layer can be obtained on the basis of the relationship between dielectric constant and FeO+TiO 2 content which was built from the measured data of the Apollo sample. The accuracy of the inversion based on CE-2 MRM data approach would be assessed by comparing our results with the Clementine data, Lunar Prospector gamma-ray data, and the laboratory data of lunar soils.

A systematic approach is presented for the sampling and interpolation over sun path. The annual sun path is described in terms of the ecliptic longitude and hour angle so that all possible positions of the sun are mapped on a rectangular domain. This enables the use of many efficient algorithms, and the bicubic interpolation with Catmull–Rom splines is proposed. It is shown that a sufficiently good accuracy can be achieved with as little as 32 sampling points for a year.

In this paper, we will establish practical and reliable mathematical model to determine the video filming locations and dates by analyzing the shadow variations of the object in the video. At first, we convert the video into image sequences which can been read by MATLAB at regular intervals. So we can analyze the image sequences to obtain coordinates of the end of the shadow in the video; in the second place, we adopt the method of data transformation based on three-dimensional reconstruction to obtain the actual coordinates of the end of the shadow; next,taking advantage of the parametric equations of the shadow and the actual coordinates of the end of the shadow, we establish goal programming model to make the sum of the error of the shadow length and deviation angle variance of the coordinate system minimum. And we can obtain solar hour angle、declination and angle latitude; Finally, we analyze the conversion relation of the solar hour angle with longitude and declination with dates to determine the video filming locations and dates.

When analyzing the data of photos and videos, it's very important to determine the shooting time and place. Usually, we can get the sun's shadow from the pictures and videos and establish different mathematical models to solve time and space positioning problems by the known parameters. Firstly, use basic amounts to establish Analemmatic sundial model; when obtaining a series of picture messages, you can get vertex coordinate data of a fixture's sun shadow on the level ground. Then to establish |y/x| scale model by Orthogonal multinomial fitting method, which can solve the latitude and longitude separately, and select 1 ‰ screening indicator as the error correction to get exact location; About shooting time, according to |y/x| scale model determining the position longitude, using MATLAB to enumerate solar declination, then develop Dynamic measurement error filter rule, select the appropriate latitude and solar declination values to calculate shooting date; when getting a video recording a fixture shadow changes, use MATLAB function of Videoreader frame image, then use Rgb2gray Function convert into gray image, finally use Ginput Function reads the image coordinates. Use those to establish a comprehensive model to get the time and location of the video shoot. Accomplish data analyzing work, which has important applications in the investigation, pointing prediction, spatial and temporal positioning and so on. Before establishing the model, there are some assumptions are as follows:  Assuming that the earth is a rule sphere, the entire radius are equal.  Assuming that the sun light is parallel to the Earth, and the communication process is unhindered.  Assuming that the number of days in a year is 365 days. After accessing to information, we can know that the sun irradiating to the Earth's surface projected shadow, whose length is related to ascension, hour angle and solar altitude, they represent the meridional coordinate of equatorial coordinate system, the difference between the right ascension (RA) and local the sidereal time (LST), the angle formed by the Earth's equatorial plane and the line between the center of the earth and sun and the angle formed by the sun's rays and earth surface tangent (1).

In recent decades, with the level of material life improves quickly, more and more people are on fire for outdoor adventure. They usually trek in desert and wasteland. However the case that compass or communication equipment is out of order happens frequently. For someone who lack direction, it is easy for them to be lost. So it is a meaningful work to research a way to find position with the help of the sun shadow. The sun shadow position is a huge project. Our paper aims to solve one link of the whole project. As the time and location change, the length of pole’s shadow change, which we make research on to get the exact function model. As is known to all, earth-sun distance is much higher than mean radius of the earth. So we can approximately think the sunlight shining on the earth is parallel light. If we believe pole length is constant. The shadow length only relates with solar elevation angle. So we can use solar declination angle, solar hour angle, geographical longitude and latitude to calculate solar elevation angle. In a word, we use parameters such as date, longitude, latitude and time to refer to above variable, with the help of geographical knowledge. And then we establish the model which describe the change of shadow length. At last we apply the model in practice. The result prove that our model is reasonable. KEYWORD: shadow positioning; solar elevation; shadow length change model 4th International Conference on Mechanical Materials and Manufacturing Engineering (MMME 2016) © 2016. The authors Published by Atlantis Press 343

We describe the motivation, design and implementation of the CORNISH survey, an arcsecond resolution radio continuum survey of the inner Galactic plane at 5 GHz using the Karl G. Jansky Very Large Array (VLA). It is a blind survey co-ordinated with the northern Spitzer GLIMPSE I region covering 10 deg < l < 65 deg and |b| < 1 deg at similar resolution. We discuss in detail the strategy that we employed to control the shape of the synthesised beam across this survey that covers a wide range of fairly low declinations. Two snapshots separated by 4 hours in hour angle kept the beam elongation to less that 1.5 over 75% of the survey area and less than 2 over 98% of the survey. The prime scientific motivation is to provide an unbiased survey for ultra-compact HII regions to study this key phase in massive star formation. A sensitivity around 2 mJy will allow the automatic distinction between radio loud and quiet mid-IR sources found in the Spitzer surveys. This survey has many legacy applications beyond star formation including evolved stars, active stars and binaries, and extragalactic sources. The CORNISH survey for compact ionized sources complements other Galactic plane surveys that target diffuse and non-thermal sources as well as atomic and molecular phases to build up a complete picture of the ISM in the Galaxy., 17 pages, 14 figures. Accepted for publication in PASP (16th-August-2012)

In this research work some mathematical models have been simulated to estimate the regression coefficients, which are also known as Angstrom coefficients, with monthly and daily average solar radiation on horizontal surface using bright sunshine hours. This study of solar energy, information on solar radiation and its components at a given location is very essential for scientists, engineers, architects, agriculturists and hydrologists for various applications such as measuring aerosol optical thickness, solar heating, cooking, drying and interior illumination of buildings. But, for developing countries like Bangladesh, we have limitation of sophisticated measuring instruments. So, we have used some latitude based empirical models to calculate an important solar radiation geometry parameter- Angstrom Coefficients for Bangladesh without any help of costly instruments. DOI: http://dx.doi.org/10.3329/ijns.v2i1.10882 International Journal of Natural Sciences (2012), 2(1): 38-42

Five algorithms for sun position computation, with validity from 2010 to 2110, are proposed and discussed. The algorithms have different accuracy levels, with maximum errors in the solar position spanning from 0.19° to 0.0027°, thus covering a wide range of possible applications. The algorithms are optimized in order to reduce their computational cost as much as possible. The extended time range of validity allows users to employ these algorithms even in long-term projects.

A generalized analytical model was developed to determine the optimum tilt angle of flat-plate solar collectors for any location worldwide. The developed analytical model was found to be directly related to the latitude φ of the location under consideration, the declination angle δ of the earth axis, and the day hour angle at sunset at any day throughout the year. The optimum tilt angle β opt was mathematically expressed by β opt = φ – tan−1[{tan δ(πω s /180)}/sin ω s ]. This model was applied to Riyadh, Kingdom of Saudi Arabia. The results were compared with those calculated by NASA, and showed very good agreement.

Sun observations provide a robust way for determining the geodetic or true azimuth at a location. Azimuth is generally defined as the angle in the plane measured from the meridian’s north (or south) to the location of the line of interest. It is common to use the north azimuth; also referred to as “azimuth”, especially in civilian surveying applications. The astronomic meridian is obtained through astronomic observations of the Sun or North Star (Polaris) and it is important since it provides one instance of the geodetic or true meridian. There are two methods for determining the sun azimuth; the first is known as the hour angle method and the other is called the altitude method. The hour angle method requires the determination of accurate time while altitude method requires accurate vertical angle. The hour angle method is more popular because it is more accurate, can be performed at any time of day and is applicable to the sun, Polaris and other stars. In this article, an error modeling framework for the errors result in the process of determining the sun azimuth using the hour angle method; namely random errors, is presented. A Gauss-Markov model is used to represent the errors in the true azimuth estimation process. Six sets of sun observation for azimuth data; three with telescope direct and three reverse, including horizontal circle’s readings and time were collected and used in order to estimate the true azimuth of a line in a study area in central Orlando, Florida, United States.

In this work, a new sun-tracking concept was proposed, and the optical performance of solar panels with such sun-tracking system was theoretically investigated based on the developed mathematical method and monthly horizontal radiation. The mechanism of the proposed sun-tracking technique is that the azimuth angle of solar panels is daily adjusted three times at three fixed positions: eastward, southward and westward in the morning, noon, and afternoon, respectively, by rotating solar panels about the vertical axis (3A sun-tracking, in short). The analysis indicated that the tilt-angle of solar panels, β3A, azimuth angle of solar panels in the morning and afternoon from due south, ϕa, and solar hour angle when the azimuth angle adjustment was made in the morning and afternoon, ωa, were three key parameters affecting the optical performance of such tracked solar panels. Calculation results showed that, for 3A tracked solar panels with a yearly fixed tilt-angle, the maximum annual collectible radiation was above 92% of that on a solar panel with full 2-axis sun-tracking; whereas for those with the tilt-angle being seasonally adjusted, it was above 95%. Results also showed that yearly or seasonally optimal values of β3A, ϕa and ωa for maximizing annual solar gain were related to site latitudes, and empirical correlations for a quick estimation of optimal values of these parameters were proposed based on climatic data of 32 sites in China.

A new design concept, called one axis three positions sun-tracking polar-axis aligned CPCs (3P-CPCs, in short), was proposed and theoretically studied in this work for photovoltaic applications. The proposed trough-like CPC is oriented in the polar-axis direction, and the aperture is daily adjusted eastward, southward, and westward in the morning, noon and afternoon, respectively, by rotating the CPC trough, to ensure efficient collection of beam radiation nearly all day. To investigate the optical performance of such CPCs, an analytical mathematical procedure is developed to estimate daily and annual solar gain captured by such CPCs based on extraterrestrial radiation and monthly horizontal radiation. Results show that the acceptance half-angle of 3P-CPCs is a unique parameter to determine their optical performance according to extraterrestrial radiation, and the annual solar gain stays constant if the acceptance half-angle, {theta}{sub a}, is less than one third of {omega}{sub 0,min}, the sunset hour angle in the winter solstice, otherwise decreases with the increase of {theta}{sub a}. For 3P-CPCs used in China, the annual solar gain, depending on the climatic conditions in site, decreased with the acceptance half-angle, but such decrease was slow for the case of {theta}{sub a}{

In previous studies, remotely sensed values of evapotranspiration are generally computed using a simplified surface energy budget model that employs a semi-empirical coefficient with combinations of Sun-synchronous satellite data and ground-based data. This approach has two main limitations, however: Sun-synchronous satellites have low temporal resolution and the estimation is limited only to a local point around the meteorological station because the models require the aid of ground-base measurements, especially air temperature. This study reduced both limitations through the supplemental use of geostationary satellite (GOES-8) data and remotely sensed estimates of all necessary parameters, including net radiation, air temperature and surface temperature. In particular, air temperature, which is an important meteorological parameter in evapotranspiration estimation, was reproduced through third-order polynomial multiple regressions (R2 = 0.88; root mean square (rms) error = 2.21 °C). The coefficient needed for the hourly estimate of evapotranspiration was represented through both a Gaussian model and a plane model. The models were constructed using surface roughness length and Sun hour angle, which replaced wind speed-a parameter that is difficult to estimate remotely over land. Assessments show that the models can depict the temporal distributions of empirical coefficients over various land-cover types. The standard error of this coefficient estimate was 0.002 mm h-1 K-1 for both time periods. A strong correlation (R2 > 0.87; rms. error

A new combined cooling, heating and power (CCHP) system is proposed. This system is driven by solar energy, which is different from the current CCHP systems with gas turbine or engine as prime movers. This system combines a Rankine cycle and an ejector refrigeration cycle, which could produce cooling output, heating output and power output simultaneously. The effects of hour angle and the slope angle of the aperture plane for the solar collectors on the system performance are examined. Parametric optimization is conducted by means of genetic algorithm (GA) to find the maximum exergy efficiency. It is shown that the optimal slope angle of the aperture plane for the solar collectors is 60° at 10 a.m. on June 12, and the CCHP system can reach its optimal performance with the slope angle of 45° for the aperture plane at midday. It is also shown that the system can reach the maximum exergy efficiency of 60.33% under the conditions of the optimal slope angle and hour angle.

The determination of the astronomical azimuth of a line is not a difficult task for surveyors any more. The aim of this paper is to analyze the theoretical details and errors in order to propose the use of ordinary total stations, for an easy, efficient and accurate determination of the astronomical azimuth of a line by the hour angle method via Polaris sightings. As many modern total stations have a built – in quartz clock they can register automatically the UTC time as well as the angle measurements (horizontal and zenith) of each observation. The total fieldwork time needed is about 10 minutes and the accuracy that may be achieved is about ± 2". This procedure will be proven to be easier than the determination of the geodetic azimuth of the same line. The calculation is independent and the result is free of the errors that the coordinates of a survey mark may contain, because they are not used. However good positional data is required from other sources. Astronomical azimuths are an alternative...

International audience; Since the Saturn orbit insertion (SOI) of the Cassini spacecraft, in July 2004, the Cassini Composite Infrared Spectrometer (CIRS) has obtained a large number of thermal infrared spectra of Saturn's rings. Over the two and a half years of observations to date, ring temperatures were retrieved for a large range of unique geometries, inaccessible from Earth. Understanding their dependencies with phase angle and local time is a clue to understanding the thermal properties and dynamics of Saturn's ring particles.Azimuthal scans of rings, which have been obtained by CIRS at constant radial distance from the planet, have been planned to measure ring temperature variations with local hour angle. Over 47 azimuthal scans for Saturn's main rings (A, B, C and Cassini Division) have been retrieved to date, on both lit and unlit sides, at different phase angles and spacecraft elevations. The first measurements of the transient thermal episode of eclipse cooling in the planetary shadow have also been obtained for all three rings.In this paper, we present an overview of all azimuthal scans obtained by the Cassini/CIRS instrument so far and the dependencies of the temperature and the filling factor with the phase angle and the local hour angle. The ring temperature varies with longitude as the input heating flux coming from Saturn and the Sun changes. The decrease in temperature with the increasing phase angle on both the lit and the unlit sides and for most of the local time also suggests the presence of slowly rotating particles. The crossing of the planet's shadow generates drastic azimuthal variations in temperature, up to 20 K in the C ring. The strong anisotropy of emission observed outside the shadow between low and high phase angles decreases when ring particles cross the shadow, suggesting that particles are almost isothermal in the shadow. This suggests a thermal inertia associated with a rotating rate of particles low enough to have a thermal contrast on their surface.The temperature in the B ring is less sensitive to the phase angle effect on the lit side, suggesting that particles are close enough to form a flat layer at a scale larger than the particle's radius. On the unlit side, particles in the B ring are less sensitive to the lack of solar input than in the C ring or in the A ring. Azimuthal variations of the filling factor in the A ring are also detected with changing ring local time. This effect might be created by the presence of gravitational instabilities (wakes).

This paper presents a model for predicting hourly solar radiation data using daily solar radiation averages. The proposed model is a generalized regression artificial neural network. This model has three inputs, namely, mean daily solar radiation, hour angle, and sunset hour angle. The output layer has one node which is mean hourly solar radiation. The training and development of the proposed model are done using MATLAB and 43800 records of hourly global solar radiation. The results show that the proposed model has better prediction accuracy compared to some empirical and statistical models. Two error statistics are used in this research to evaluate the proposed model, namely, mean absolute percentage error and root mean square error. These values for the proposed model are 11.8% and −3.1%, respectively. Finally, the proposed model shows better ability in overcoming the sophistic nature of the solar radiation data.

In the first part of this series, we discussed the celestial sphere and Aryabhata’s principle of axial rotation; in this part we shall discuss in detail the concept of sidereal day and then mention Aryabhata’s computations on the duration of sidereal day.

To investigate the variability of the flux density, observations of four power radio sources (3C144, 3C274, 3C405 and 3C461) were carried out on the radio telescope URAN-4 at two frequencies, 20 and 25 MHz, during 1998–2005. The automatic procedure for obtaining the observations is considered briefly in this paper. The results of previous procedures are presented in the tables. They contained information that allows the vast amount of material that has been gathered to be analysed in more detail as follows: estimation of the source flux densities, study of ionospheric scintillations, investigation of the dependence of the direction pattern on the hour angle and the solving of other tasks. The dependence of the URAN-4 direction pattern on the hour angle is cited as an example of the mean procedure using many observation data. Long-time observation series allowed the cycle year dependence of the ionospheric scintillation index to be obtained.

An investigation of the stability of the transfer function of the European Southern Observatory's Very Large Telescope Interferometer has been carried out through observations of Fomalhaut over a wide range in hour angle. No significant variation in the transfer function was found for the zenith angle range 5-70 degrees. The projected baseline varied between 139.7 m and 49.8 m during the observations and, as an integral part of the determination of the transfer function, a new accurate limb-darkened angular diameter for Fomalhaut has been established. This has led to improved values for the emergent flux, effective temperature, radius and luminosity., Comment: 6 pages, 4 figures, uses an.cls, accepted for publication in Astron. Nacht

Practical measurement of the passage of time requires the notion of a repeating phenomenon. The Earth's rotation has traditionally fulfilled this requirement. To cope with the impracticality of making precise measures of the Sun's hour angle or altitude, particularly in uncooperative weather conditions, various devices have been employed, but all have been calibrated with respect to astronomical phenomena related to the Earth's rotation, or to its orbital motion with respect to the Sun. Modern requirements for timing precision coupled with an increased understanding of the variability of the Earth's rotational speed are likely to bring about a change in the traditional relationship between precise timekeeping and astronomy. The historical background of this relationship and the current definitions are reviewed to show the development of timekeeping capabilities and the growing need for precise timekeeping. Possible future developments are outlined along with their advantages and disadvantages.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

I describe a method for quickly and accurately determining the plate parallelism in a tunable Fabry-Perot interferometer. The method takes advantage of the fact that our Fabry-Perot is installed in a spectropolarimeter: we measure profiles of solar or telluric absorption lines in three differently polarized telescope subapertures and use the residual polarization profiles to determine the plate parallelism error. An example of the error as a function of time during the observing day is also shown; it changes in a consistent way with telescope hour angle but the drift is enough to require frequent adjustment.

Mathematical formulas for estimating the hourly and daily radiation incident on planes of azimuth three step tracking and hour angle three step tracking have been derived in this paper. Based on the hourly solar radiation data of an average day in each month at Er-Lian-Hao-Te city, the hourly and monthly radiation received by planes of these two kinds of tracking have been calculated. The results show that in this district, one axis azimuth three step tracking and hour angle three step tracking could, respectively, obtain 66.5% and 63.3% higher radiation than that on the horizontal surface all year. Moreover, a two axis azimuth three step tracking plane could receive 72% more radiation than the horizontal surface. (C) 2002 Elsevier Science Ltd. All rights reserved.

We present observations of a sample of Herbig AeBe stars, as well as the FU Orionis object V1057 Cygni. Our K-band (2.2 microns) observations from the Palomar Testbed Interferometer (PTI) used baselines of 110m and 85m, resulting in fringe spacings of 4 mas and 5 mas, respectively. Fringes were obtained for the first time on V1057 Cygni as well as V594 Cas. Additional measurements were made of MWC147, while upper limits to visibility-squared are obtained for MWC297, HD190073, and MWC614. These measurements are sensitive to the distribution of warm, circumstellar dust in these sources. If the circumstellar infrared emission comes from warm dust in a disk, the inclination of the disk to the line of sight implies that the observed interferometric visibilities should depend upon hour angle. Surprisingly, the observations of Millan-Gabet, Schloerb, and Traub 2001 (hereafter MST) did not show significant variation with hour angle. However, limited sampling of angular frequencies on the sky was possible with the IOTA interferometer, motivating us to study a subset of their objects to further constrain these systems.

Ultraviolet (UV) sensors on a geostationary orbit (GEO) have important potential value in atmospheric remote sensing, but the satellites orbit mode of it is quit different from sun-synchronous orbit satellites, which result in the significant diurnal and seasonal variations in radiation environment of earth observation and radiation signal of sensors, therefore, the effect to sensor radiometric performance, such as signal to noise ratio for atmospheric ultraviolet remote sensing caused by variations of solar angle is significant in the performance design of sensors. The synthetic ultraviolet sensor is set at the geostationary orbit, 36000 km away from the sea level of the Equator with 8.75 degree field of view, and the subsatellite track point of which is located at 90 degrees east longitude and Equator. The Satellite scanning angles (SA) from 0 to 8.648 degree that cover the earth surface are selected corresponding to the 10 degrees equal interval view zenith angle, and the SA from 8.648 to 8.785 degree cover the earth lamb 100 km far away from earth tangent point. Based on the MODTRAN4 model, on normal atmospheric conditions, the distributions of the UV upwelling radiance from surface or limb viewing path of the earth could be simulated with the change of sun's right ascension. Moreover, the average signal to noise ratio to the atmospheric sounding is obtained in different UV spectra using the Sensor signal to noise ratio model. The results show that the thresholds range, tendency and shape of signal to noise ratio have a variety of features affected by variation of Sun hour angles and declinations. These result and conclusions could contribute to performance design of UV sensors on the geostationary orbit.

(Abridged) Atmospheric dispersion and field differential refraction impose severe constraints on widefield MOS observations. Flux reduction and spectral distortions must be minimised by a careful planning of the observations -- which is especially true for instruments that use slits instead of fibres. This is the case of VIMOS at the VLT, where MOS observations have been restricted, since the start of operations, to a narrow two-hour range from the meridian to minimise slit losses. We revisit in detail the impact of atmospheric effects on the quality of VIMOS-MOS spectra. We model slit losses across the entire VIMOS FOV as a function of target declination. We explore two different slit orientations at the meridian: along the parallactic angle (North-South), and perpendicular to it (East-West). We show that, for fields culminating at zenith distances larger than 20 deg, slit losses are minimised with slits oriented along the parallactic angle at the meridian. The two-hour angle rule holds for these observations using N-S orientations. Conversely, for fields with zenith angles smaller than 20 deg at culmination, losses are minimised with slits oriented perpendicular to the parallactic angle at the meridian. MOS observations can be effectively extended to plus/minus three hours from the meridian in these cases. In general, night-long observations of a single field will benefit from using the E-W orientation. All-sky or service mode observations, however, require a more elaborate planning that depends on the target declination, and the hour angle of the observations. We establish general rules for the alignment of slits in MOS observations that will increase target observability, enhance the efficiency of operations, and speed up the completion of programmes -- a particularly relevant aspect for the forthcoming spectroscopic public surveys with VIMOS., Accepted to A&A. 11 pages, 15 figures. This paper presents the new recommendations for optimal slit alignment in VLT/VIMOS observations

Just like navigation for a naval ship or airplane, we observe that time and space relations are linked together, and can be represented and communicated as geographic information. In this chapter we describe how to manipulate that geographic information in terms of angles, and use key relations from spherical trigonometry to make time and space relations easy to calculate with a computer. For our purposes: angles are coordinates in space and time. We describe the spatial and temporal relationships of the Sun relative to the Earth and for an Observer on the surface of Earth relative to the Sun at any given time. These angular relationships are then used to describe in detail the relative orientation of a Solar Energy Conversion System (SECS) surface relative to the moving Sun, while identifying the times that local shadows might obscure our SECS.

Publisher Summary This chapter describes the movements of the sun relative to the earth that give to the sun its east–west trajectory across the sky. The variation of solar incidence angle and the amount of solar energy received are analyzed for a number of fixed and tracking surfaces. The environment in which a solar system works depends mostly on the solar energy availability. For most solar energy applications, one needs reasonably accurate predictions of where the sun will be in the sky at a given time of day and year. In the Ptolemaic sense, the sun is constrained to move with 2 degrees of freedom on the celestial sphere; therefore, its position with respect to an observer on earth can be fully described by means of two astronomical angles, the solar altitude and the solar azimuth. An approximate method for calculating these angles is by means of sun-path diagrams. Also general weather of a location is required in many energy calculations. This can be presented as a typical meteorological year (TMY) file.

We demonstrate the global secular rotation of the Celestial Ephemeris Origin (CEO), the nonrotating origin (NRO) for Earth's equator adopted recently by the IAU. The current speed of this global rotation is as high as -415 yr-1, where the minus sign indicates that the CEO rotates clockwise with respect to the inertial frame when viewed from the north celestial pole. Such secular rotation does not exist for some geometrically defined longitude origins. We think that the existence of a global secular rotation means that the CEO, and the NRO in general, is not appropriate to be specified as the x-axis of a celestial coordinate system.

Finding the direction of a line is done simply and accurately with a multiyear interactive computerized almanac (Mica), a theodolite, and a hand-held programmable calculator. Mica is the Multiyear Interactive Computer Almanac that is available from the U.S. Naval Observatory. An astronomic azimuth from station 081 to station 080 is measured with a set of six solar observations and the resulting average azimuth is compared to the value established by the Vermont Agency of Transportation (VAT), using the global positioning system. Each of the six sun shots is made by an independent observer, who in this study is represented by a first-year civil engineering student. Three readings were done with the telescope reversed and three were taken with the telescope direct. The local hour angle (LHA) method is used to calculate the astronomic azimuth. The solar constants for the equation of time (EOT), for declination (δ), and for semidiameter (SD) are found in Mica. The astronomic Azimuth 081–080 is 235° 15’ 50" from the student readings and is 235° 15’ 56" from VAT data.

Space impacts retrieved to Earth, such as those on LDEF and EuReCa, have led to an unprecedentedly high definition of the impact environment in Earth orbit. This leads to (1) a penetration flux distribution (2) angular dependence of the flux (3) physical signatures of the penetration through thin films and (4) chemical evidence of impact residues. At micron dimensions, space retrieved surfaces show an “excess” flux, mainly when exposed to the leading (ram) direction, attributable to space debris or to micrometeoroids captured in Earth orbit. We present results of studies to determine the capture efficiency of the Earth to interplanetary dust and the dwell time of microparticles in eccentric orbits. Effects of the solar hour angle of the initial argument of perigee at capture are critical and, especially, the increase or decrease of atmospheric density at subsequent perigee passages due to solar heating cycles. Results will be presented of interest to the relative importance of space debris and of astrophysical sources.

The chapter starts by describing briefly the basic features of sun and then proceeds to deriving the relevant equations that allow the calculation of several parameters pertaining to the sun namely the eccentric anomaly, hour angle, and the position of the sun (azimuth and altitude) amongst others. The relevant formulae are valid at any spacial and temporal location on the earth. The rule which allows us to compute the sun’s position at any time is cross-checked with the US National Renewable Energy Laboratory’s Solar Position Algorithm and is shown to be in good agreement (\(

This paper proposes an algorithm to calculate the optimum tilt angle of solar panels by means of global horizontal solar radiation data, provided from Earth-based meteorological stations. This mathematical modeling is based on the maximization of the theoretical expression of the global solar irradiation impinging on an inclined surface, with respect to the slope and orientation of the panel and to the solar hour angle. A set of transcendent equations resulted, whose solutions give the optimum tilt and orientation of a solar panel. A simulation was carried out using global horizontal solar radiation data from the European Solar Radiation Atlas and some empirical models of diffuse solar radiation. The optimum tilt angle resulted was related to latitude by a linear regression with significant correlation coefficients. The standard error of the mean values resulted increased significantly with latitude, suggesting that unreliable values can be provided at high latitudes.

This paper deals with the distributive characteristics of the occurrence time of earthquakes with respect to the aftershock sequences of strong earthquakes. The distribution of lunar and solar local hour angles at the time of commencement of moderate and strong aftershocks indicates that the time of commencement of moderate and strong aftershocks is modulated by the positions of the sun and moon and then the earthquake restrained time zones exists also. In this paper the differences of earthquake restrained time zones between the preshock sequences and the aftershock sequences are compared, and the possible mechanism is analyzed preliminarily. And the possible maximum scope of accuracy in predicting the occurrence time of an earthquake is determined as well.

This paper deals with the distributive characteristics of the occurrence time of earthquakes with respect to the aftershock sequences of strong earthquakes. The distribution of lunar and solar local hour angles at the time of commencement of moderate and strong aftershocks indicates that the time of commencement of moderate and strong aftershocks is modulated by the positions of the sun and moon and then the earthquake-restrained time zones exists also. In this paper the differences of earthquake-restrained time zones between the preshock sequences and the aftershock sequences are compared, and the possible mechanism is analyzed preliminarily. And the possible maximum scope of accuracy in predicting the occurrence time of an earthquake is determined as well.

This paper will present a variant of the 3-D computer simulating application for the development of simultaneous astronomical and historical events investigations. The purpose was to identify the historical events by the celestial sphere instantaneous state subject to geospatial information that we can simulate. We proceed from the assumption that both the Earth’s surface with objects of material culture must itself be a historical source and a calendar of celestial events is the only true and accurate calendar for recording historical events over very long periods. We detect that the Earth's axial tilt was equal 1/3 х 70°32′ (23°30′40″) while 70°32′ is a central angle of a Plato’s polyhedron. We inscribed Plato’s polyhedrons in the celestial sphere and simulated time-dependent relative positioning of the zenith above geographical objects, fundamental planes of celestial coordinate systems and polyhedrons in imaginable situations. It was ascertained that ecliptic longitudes of zenith above some cities were equal to central angles of Plato’s polyhedrons on the winter solstice in the year 1440. We interpret results as follows: locations of some cities were chosen so that zenith above them could coincide with vertices of the Plato’s polyhedrons inscribed in a celestial sphere symmetrically about an ecliptic plane.

In order to reduce residual differences between measured values of the direct beam and values estimated from the coefficients σ and Kt when a single annual correlation expression is used, we have divided the year into three periods according to the sunset hour angle, ωs at our site: winter; spring/autumn; and summer. Expressions of correlation have been derived for each of these three periods. Use of three seasonal expressions gives a more accurate estimate than does a single annual expression.

Space-geodetic measurement systems are capable of determining: (1) a terrestrial, body-fixed reference frame defined in practice by the stated positions and secular motions of a set of observing stations, (2) a celestial, space-fixed reference frame defined in practice by the stated locations of celestial objects, and (3) the rotation parameters linking these two frames together. Five parameters are conventionally used to specify the orientation of the terrestrial frame with respect to the celestial frame: two nutation parameters, two polar motion parameters, and one spin parameter. The celestial ephemeris pole (CEP) is defined as the north pole of that axis about which the spin parameter (UT1) is measured. The two nutation parameters locate the CEP in the celestial frame, and the two polar motion parameters locate the CEP in the terrestrial frame. By examining the frame transformation matrices, an expression relating the location of the rotation pole to that of the CEP can be derived. In order to compare theoretical predictions with observations, results of models for the effect on the nutations of geophysical excitation processes such as diurnal oceanic current and sea level height variations should not only be given in terms of the location of the CEP (rather than of the rotation pole), but must also account for the resonance effects of the free core nutation.

A Microsoft Excel application has been developed to utilize eclipsing binary elements to calculate binary ephemerides that are useful in a program of observing binary systems. Binary star systems consist of two stars orbiting a common center of mass. Consistent monitoring of eclipsing binary stars is important for establishing fundamental astronomical parameters, such as mass and composition of the stellar system. The application that was developed supports effective use of resources in such monitoring applications. The main quantities computed by the application at the time of the eclipse include: local time, Julian date, starting Epoch, altitude of the system, phase of the moon, Local Mean Sidereal Time, and Local Hour Angle. Other quantities computed by the application include current Universal Time (UT), UT/Local Time correction, Julian Date, and current moon phase/percent illuminated. The observing application has been demonstrated to be effective in practical application to obtain differential photometry data for SV Camelopardalis, a system of interest because of variability in its period caused by a third body. The application can be easily modified for use with other highly periodic astronomical systems, for instance transits of extrasolar planets.

In this paper, an overview of the production and consumption of Kuwait electrical energy, installed capacity and peak loads are presented. The results show that Kuwait has a serious situation because of the electrical energy lacking and load peaking. Based on the fact that Kuwait has enough budgets to transform all the power station powered by oil with renewable energy sources turning to greener Kuwait. The paper also is identifying and analyzing the geographical and temporal variability of solar energy inside Kuwait. The fundamental solar models are modified to estimate and identify daily and hourly solar radiation on horizontal surfaces on the basis of the more readily available meteorological data. The presented results prove that Kuwait has an abundance of solar energy capability in terms of almost cloudless atmosphere for nine months and twelve hours solar time a day over the year. The daily global and monthly averaged solar intensity on horizontal surface at Kuwait area is ranging from 3 Wh/m2 in winter to 8 kWh/m2 in summer. Monthly averaged clear sky solar radiation on horizontal surfaces at Kuwait area is ranging from 500W/m2/day to 1042W/m2/day.

In 2009 we started an intense radial-velocity monitoring of a few nearby, slowly-rotating and quiet solar-type stars within the dedicated HARPS-Upgrade GTO program. The goal of this campaign is to gather very-precise radial-velocity data with high cadence and continuity to detect tiny signatures of very-low-mass stars that are potentially present in the habitable zone of their parent stars. Ten stars were selected among the most stable stars of the original HARPS high-precision program that are uniformly spread in hour angle, such that three to four of them are observable at any time of the year. For each star we recorded 50 data points spread over the observing season. The data points consist of three nightly observations with a total integration time of 10 minutes each and are separated by two hours. This is an observational strategy adopted to minimize stellar pulsation and granulation noise. We present the first results of this ambitious program. The radial-velocity data and the orbital parameters of five new and one confirmed low-mass planets around the stars HD20794, HD85512, and HD192310 are reported and discussed, among which is a system of three super-Earths and one that harbors a 3.6 Earth-mass planet at the inner edge of the habitable zone. This result already confirms previous indications that low-mass planets seem to be very frequent around solar-type stars and that this may occur with a frequency higher than 30%, 18 pages, 22 figures, accepted by A&A on 15/08/2011 with reference AA/2011/17055. Radial velocity data will be available through CDS

The calculation of solar radiation received at a particular place and at a particular time, involves many factors like rotation and revolution of the earth, atmospheric attenuations, atmospheric conditions, time of day and year, geographic location of place, and site location of collector, tilt of collector, type of its variation due to seasonal and atmospheric conditions and show how calculation for horizontal and tilted surfaces may be done based on geometrical and seasonal consideration. Certain angles have been defined for specification of the sun's position in the sky like solar altitude and azimuth angles and the sun's apparent path across the sky found on the celestial sphere. The method of defining position of a point on the earth's surface with respect to the sun's rays by means of latitude, hour angle and declination is also shown. Depletion of extraterrestrial radiation by absorption, scattering etc. is also discussed in detail in this paper.

Captain P.V.H. Weems was a graduate of the U.S. Naval Academy in the class of 1912 and co-founder of our Institute of Navigation. Already an experienced navigator, he was aboard one of the ships stationed in a line across the Atlantic Ocean for the first successful trans-Atlantic crossing by Navy NC4 aircraft. The ships thus stationed acted as beacons and monitored the progress of the flight. By his own account, this event more than any other, started his lifetime pursuit of developing better methods and instrumentation for long range air navigation. By the time that Lindbergh made his historic flight, Weems reputation in navigation was becoming established. After the return of Lindbergh form Paris the Navy temporarily detached Lt. Comdr. Weems form other duties to teach Lindbergh celestial navigation. After his first retirement in the early 30’s, Weems continued his efforts in his own small business called “The Weems System of Navigation”. Because of this many pilots knew him best for the Weems Plotter, the E6B Computer, his text books on both Marine and Air Navigation and other Piloting and Dead Reckoning instruments. His principal interest and thrust however was always on the improvement of celestial navigation. Then as now this problem involved five elements: observing instruments, time keeping instruments, storage and use of Almanac data, solution of the spherical triangle and plotting or recording of the “fix” or position. The persistent devotion of Capt. Weems to the problem produced outstanding results in all five areas. Capt. Weems worked with Ed Link in this country and with Hughes in England on aircraft bubble sextants. In the field of timing, his Weems Second Setting Watch led the way to the aircraft hack watches of WWII, and to the development of the Lindbergh Hour Angle Watch. He designed the modern almanacs which tabulate Greenwich Hour Angle. For sight reduction his “Line of Position Book” was the first of the so-called short methods. The “Star Altitude Curves” were his proudest achievement and were adopted by the Army Air Corps just prior to WWII. His love of people and the force of his personality, together with his refusal to ever accept the answer “NO” gave us this Grand Old Man of Navigation.

The potential of a previous model for calculating direct and diffuse solar radiation is further explored by employing the model to study the characteristic distribution of hourly insolation for six years (1980–1985) at Ibadan. The study covers “clear” and “moderately clear” sky conditions for which the turbidity β < 0.175, and for which the range of β, the probability of occurrence in the year is 60.63%. The computed results yield correlations of the hourly-ddaily insolation ratios rh and rd with the sunset hour angle θs which are in satisfactory agreement with, and therefore confirm, the work of Liu and Jordan as well as Collares-Pereira and Rabl. The present results also show that the hourly diffuse ratio kd′ is a function of both the hourly clearness index kT and time t from solar noon: this explains why the previous plot of Orgill and Hollands of kd′ vs kT without accounting for time effect gives an unacceptably wide scatter. Further, the present correlation of the hourly diffuse coefficient kd with kT yields similar trends to those found in the previous work of Iqbal.

This paper presents rigorous equations, useful with computer reduction of celestial sights, which correct the Greenwich Hour Angle and declination of a celestial body for the motion of a vessel. Advancing a circle of position in this way maintains the relationship between the geographical position of the body and the vessel, and hence is the best method for advancing an observation.

The paper deals with the automatic grid azimuth determination of an object on the earth using the electronic theodolite Kern E2 by observing the sun, a star, or a planet. The observation time and the readings of horizontal and vertical circles of the electronic theodolite enter automatically the electronic calculator Hewlett-Packard HP41CX. The calculator computes the grid azimuth of the terrestrial object and directs the observer what to do. Therefore, even a personnel without specific high education can make observations. For the solar observations it is not necessary to have an astronomical almanac, because the program computes the solar coordinates. The general input data, together with the measured ones, can be stored on a magnetic cassette and later on, if necessary, one can correct the general data and recalculate the azimuth. The method proved to be very practical in the field work.