Difference Of Longitude Research Articles

The correspondence of Giovanni Santini and Giuseppe Lorenzoni, directors of the Astronomical Observatory of Padua in the 19th century

Giovanni Santini was appointed director of the Astronomical Observatory of Padova from 1817 to 1877. His scientific correspondence covers a period from 1807 to 1874. Most of the letters are from Italian and European astronomers, mainly concerning astronomical subjects. In actual fact, all Santini’s activity was devoted to the classical astronomy, mainly to the new comets and planets orbit calculation, as far as to the compilation of a catalogue of almost ten thousand stars. From 1821 to 1828, he was involved in geodetic observations in order to determine the difference of longitude between Milan-Padua and Padua-Fiume. Giuseppe Lorenzoni was appointed director after Santini’s death, from 1877 to 1913. Since 1873, he took part in the Italian Geodetic Commission to which he devoted almost all his scientific activity. Lorenzoni’s scientific correspondence was partly lost for war reasons. A partial correspondence with Giovanni Virginio Schiaparelli and almost the complete correspondence with Pietro Tacchini, were recovered after the second World War. Santini and Lorenzoni correspondence cover a period about a hundred years long. So, it is an important tool of knowledge for the history of Padova Astronomical Observatory in the 19th century, for its scientific activity, and for the relationship among Italian and European astronomers and institutions.

The periodic variation of 6.7 days for total solar radiation

AbstractAnalyzing the power spectrum of Total Solar Irradiance (TSI) for the period from 2003 February 25 to 2009 July 6, observed with the Total Irradiance Monitor (TIM) onboard SOlar Radiation and Climate Experiment (SORCE), we found that there are quite a number of periodic variations. The outstanding shortest one is the period of 6.7 days, about one fourth of the period of solar rotation. Checking the solar magnetic field for the same period of time observed with MDI onboard SOHO, we found that there is about 90 degree difference in longitude for the distribution of solar magnetic field. We therefore conclude that both the 90 degree difference in longitude for the distribution of solar magnetic field and the solar rotation are the reason resulting in the periodic variation of 6.7 days for the total solar radiation.

Biogeographic distributions and environmental controls of stream diatoms in the Canadian Arctic Archipelago

Streams are amongst the most sensitive ecosystems in Arctic regions to environmental change. Although diatoms are excellent indicators of environmental change, little information is available about stream diatom distributions across the vast Canadian High Arctic. We sampled 42 streams from nine islands in the Canadian Arctic Archipelago to study their diatom floras and evaluate the influences of biogeographic and environmental variables on species distributions. Highly divergent diatom communities were identified, with 100% species overturn between the most dissimilar communities. Taxa including Hannaea arcus (Ehrenberg) Patrick were characteristic of streams from all regions; other common taxa included Nitzschia perminuta (Grunow) Peragallo, Rossithidium petersenii (Hustedt) Round & Bukhtiyarova, Achnanthidium minutissimum (Kützing) Czarnecki, and Eucocconeis laevis (Østrup) H. Lange-Bertalot. Canonical correspondence analysis indicated that diatom assemblages were significantly related to differences in pH, temperature, latitude, and longitude, which together explained 14.7% of species variability. Analysis of similarities indicated that communities did not differ significantly between epilithic and epiphytic samples and that there were weak but significant differences between the diatom communities in our three regions. These data provide important baseline information for future biomonitoring efforts as well as for paleolimnological studies of past stream hydrology.

Long term evolution of quasi-circular Trojan orbits

Trojan asteroids undergo very large perturbations because of their resonance with Jupiter. Fortunately the secular evolution of quasi circular orbits remains simple—if we neglect the small short period perturbations. That study is done in the approximation of the three dimensional circular restricted three-body problem, with a small mass ratio μ—that is about 0.001 in the Sun Jupiter case. The Trojan asteroids can be defined as celestial bodies that have a “mean longitude”, M + ω + Ω, always different from that of Jupiter. In the vicinity of any circular Trojan orbit exists a set of “quasi-circular orbits” with the following properties: (A) Orbits of that set remain in that set with an eccentricity that remains of the order of the mass ratio μ. (B) The relative variations of the semi-major axis and the inclination remain of the order of \({\sqrt{\mu}}\) . (C) There exist corresponding “quasi integrals” the main terms of which have long-term relative variations of the order of μ only. For instance the product c(1 – cos i) where c is the modulus of the angular momentum and i the inclination. (D) The large perturbations affect essentially the difference “mean longitude of the Trojan asteroid minus mean longitude of Jupiter”. That difference can have very large perturbations that are characteristics of the “horseshoes orbit”. For small inclinations it is well known that this difference has two stable points near ±60° (Lagange equilibrium points L4 and L5) and an unstable point at 180° (L3). The stable longitude differences are function of the inclination and reach 180° for an inclination of 145°41′. Beyond that inclination only one equilibrium remains: a stable difference at 180°.

Genotype by Environment Interaction in Pinus sylvestris L. in Southern Sweden

AbstractTo estimate the amount of genotype by environment interaction (G x E) data was obtained within the Swedish breeding program of Pinus sylvestris L. The calculations were based on estimates of G x E expressed by the genetic correlations across trials. In total, 66 progeny trials were included coming from 17 different test series. The number of parents tested per progeny trial was in average 52. Some parents were tested in several series and in total 812 parents were represented in the study. The results of our study showed that the amount of G x E for growth traits in Pinus sylvestris in southern Sweden was low. The median genetic correlation across trials for height, height increment and diameter were in the range 0.75-0.80 and the pattern of interaction was largely unpredictable from site differences in site index, latitude, longitude and altitude.

Dynamic portrait of the planetary 2/1 mean-motion resonance - II. Systems with a more massive inner planet

We analyse the global structure of the phase space of the planar planetary 2/1 mean-motion resonance in cases where the outer planet is more massive than its inner companion. Inside the resonant domain, we show the existence of two families of periodic orbits, one associated to the librational motion of resonant angle (σ -family) and the other related to the circulatory motion of the difference in longitudes of pericentre (�� -family). The well-known apsidal corotation resonances (ACR) appear as intersections between both families. A complex web of secondary resonances is also detected for low eccentricities, whose strengths and positions are dependent on the individual masses and spatial scale of the system. The construction of dynamical maps for various values of the total angular momentum shows the evolution of the families of stable motion with the eccentricities, identifying possible configurations suitable for exoplanetary systems. For low‐moderate eccentricities, several different stable modes exist outside the ACR. For larger eccentricities, however, all stable solutions are associated to oscillations around the stationary solutions. Finally, we present a possible link between these stable families and the process of resonance capture, identifying the most probable routes from the secular region to the resonant domain, and discussing how the final resonant configuration may be affected by the extension of the chaotic layer around the resonance region.

Joining the observatories of Paris and Greenwich

In the closing years of the eighteenth century, France and Britain enjoyed a period of external peace that their scientific communities put to good use by finding an objective common to the leading academic institutions: the Académie royale des sciences in France, and the Royal Society in England. This was not an entirely new concept; the novelty was that the objective would be brought about by teams from each side working outside their own borders. It was part of both nations' long-running search for a means of establishing longitudes on land and at sea. The specific objective, however, was confined to establishing the accurate difference in longitude between the meridian of Greenwich Observatory and that of the Observatoire de Paris. Previous astronomical measurements, derived from the times of certain eclipses or transits as recorded at each observatory, were acknowledged to be inaccurate.

An infuriating geniusAnita McConnell, Jesse Ramsden (1735–1800): London's leading scientific instrument maker . Ashgate Publishing Limited, Aldershot, 2007. pp. 340, £60.00 (hardback). ISBN 978-0-7546-6136-8.

Anita McConnell, Jesse Ramsden (1735–1800): London's leading scientific instrument maker . Ashgate Publishing Limited, Aldershot, 2007. pp. 340, £60.00 (hardback). ISBN 978-0-7546-6136-8. Scientific instrument makers are rarely afforded the limelight by historians. Yet, as Martin Rees's foreword

Near infra-red spectroscopy of the asteroid 21 Lutetia

Aims. In the framework of the ground-based science campaign dedicated to the encounter with the Rosetta spacecraft, the mineralogy of the asteroid (21) Lutetia was investigated. Methods. Near-infrared (NIR) spectra of the asteroid in the 0.8−2.5 μm spectral range were obtained with SpeX/IRTF in remote observing mode from Meudon, France in March and April 2006. We analysed these data together with previously acquired spectra - March 2003, August 2004. I-band relative photometric data obtained on 20 January 2006 using the 105 cm telescope from Pic du Midi, France has been used to build the ephemeris for physical observations. A χ2 test using meteorite spectra from the RELAB database was performed in order to find the best fit of complete visible + infrared (VNIR) spectra of Lutetia. Results. The new spectra reveal no absorption features. We find a clear spectral variation (slope), and a good correspondence between spectral variations and rotational phase. Two of the most different spectra correspond to two opposite sides of the asteroid (sub-Earth longitude difference around 180◦). For the neutral spectra a carbonaceous chondrite spectrum yields the best fit, while for those with a slightly positive slope the enstatitic chondrite spectra are the best analog. Based on the chosen subset of the meteorite samples, our analysis suggests a primitive, chondritic nature for (21) Lutetia. Differences in spectra are interpreted in terms of the coexistence of several lithologies on the surface where the aqueous alteration played an important role.

Up to 1-hour forecasting of radiation hazards from solar energetic ion events with relativistic electrons

[1] The sudden and prompt occurrence of solar energetic particle events poses a hazard to manned space activities and interferes with robotic space science missions. This study demonstrates the possibility of short-term forecasting of the appearance and intensity of solar ion events by means of relativistic, near–light speed electrons. A list of the most severe proton events measured by GOES 8 in the years 1996–2002 serves as a basis to derive the fundamentals of the forecasting method with statistical and superposed epoch techniques. The Comprehensive Suprathermal and Energetic Particle Analyzer (COSTEP) on SOHO provides relativistic electron and <50 MeV proton observations at 1 AU. With a subset of solar particle events (SPEs) where the location of the associated flare on the Sun has been determined, we find that (1) relativistic electrons always arrive at 1 AU ahead of nonrelativistic SPEs allowing their forecasting; (2) the intensity increase of both, electrons and protons alike, depends on the magnetic connection, i.e., the magnetic longitude difference between the observer and the flare; and (3) as coming from one source under near-identical propagation conditions, significant correlations exist that show that the early electron intensity and increase can be utilized as a matrix to forecast the upcoming proton intensity. The study demonstrates one initial empirical forecasting technique with electron and proton observations in 2003.

Heterometrías de extremidades inferiores

The heterometry is a frequent alteration that rebounds in the whole apparatus locomotive. There is two types of heterometry, the estructural and the functional one exist. The structural one is due to differences of longitude in some of the bony segments (femur and/or tibia), and it causes an imbalance of gluteal, pelvic and scapular levels. The functional one is characterized to be caused by different foot loadings, mainly for asymmetric pronation. This position can look a structural heterometry, although the cause is not in the different measure of the bony segments. The treatment that can be carried out from the podologist point of view is different, since the structural one requires the inclusion of a material in the support to plant. The functional one on the other hand doesn’t require of rise, but of the different correction of the position in each foot.

Spatial and bathymetric trends in Harpacticoida (Copepoda) community structure in the Northern Gulf of Mexico deep-sea

Harpacticoid copepod community structure was analyzed at 43 stations in the northern Gulf of Mexico deep-sea to test regional and bathymetric patterns of diversity in relation to environmental variables and topographic complexity of the continental slope. Depth, longitude, and proximity to the Florida Escarpment significantly affect average phylogenetic diversity, but basins and canyons do not. Multivariate analysis reveals a significant inverse relationship between diversity and POM flux, which is confirmed by significant region-scale depth and longitude differences. Although species richness declines linearly with increasing depth, the expected number of species (rarefraction) is maximized at approximately 1200 m, and average taxonomic and phylogenetic diversity continue to increase with depth, suggesting greater morphological or functional harpacticoid diversity with increasing depth. Most stations have unique species compositions, suggesting high regional (2200 species) and global (10 5–10 6 species) diversity by extrapolation. Therefore, processes maintaining harpacticoid diversity in the northern Gulf of Mexico deep-sea seem to rely on both small-scale dispersal and large-scale food supply mechanisms.

Response of ionosphere to the great geomagnetic storm of September 1998: Observation and modeling

We present the results derived from investigating of the ionospheric effects of the great geomagnetic storm on September 24–27, 1998 based on analyzing the data obtained at ionospheric stations located in the region of Siberia and the Far East. For the sake of comparison we have also introduced the data from some European stations. In addition to the vertical-incidence sounding data the measurements from the Irkutsk incoherent scatter radar are used. It is obtained that the intense negative disturbances during the main phase of the storm are observed at all stations under investigation. A comparison of the foF2 variations for the two meridians shows that even with a relatively small difference of longitudes (45°), the recovery phase has substantial differences of ionospheric disturbances. On September 26, the positive disturbances are observed and persist the following day at all stations except Salekhard and the Norilsk chain. At the Norilsk chain and at Salekhard the negative disturbances recurred after positive disturbances. The sign reversal of disturbance during the recovery phase extends over in the further displacement from the west to the east. An interpretation of the measurements includes their comparing with the results of calculations in terms of a numerical model of the ionosphere and plasmasphere. The modeling results are in the satisfied agreement with the measurements. According to the model calculations the sign of the ionospheric disturbance is changed from negative to positive as the result of combined effects of corpuscular and photo ionization. The sign of ionospheric disturbance is determined by a local time at which the magnetic storm has begun.

Planetary migration and extrasolar planets in the 2/1 mean-motion resonance

In this paper, we present a new set of corotational solutions for the 2/1 commensurability, including previously known solutions and new results. Comparisons with observed exoplanets show that current orbital fits of three proposed resonant planetary systems are consistent with apsidal corotations. We also discuss the possible relationship between the current orbital elements fits of known exoplanets in the 2/1 mean-motion resonance and the expected orbital configuration due to migration. We find that, as long as the orbital decay was sufficiently slow to be approximated by an adiabatic process, all captured planets should be in apsidal corotations. In other words, they should show a simultaneous libration of both the resonant angle and the difference in longitudes of pericenter.

Magnetic connection from the Earth to the solar corona, flare positions and solar energetic particle observations

Solar energetic particle (SEP) events are often associated with solar flares. Such particles propagate through the interplanetary medium, where significant levels of magnetic turbulence are found. We study the magnetic connection from the Earth to the solar corona in three dimensional magnetic turbulence. In the numerical simulation, different turbulence levels and solar wind velocities can be used. Input to the simulation is from web-based data sets, and comparison is made with the solar flare observations contained in the Goes catalogue for the years 1996, 1997, 1998, following solar minimum. For this data set, we find that SEPs can reach the Earth when the difference in the heliographic longitudes of the flare and of the magnetic foot point of the Earth is 25°–30° at most. On the other hand the longitudinal angular semi-width of the magnetic field line random walk in the solar wind, when mapped to the solar corona, is found to be typically $6^\circ$–10°. The discrepancy between the two values can be explained either by the presence of a flare – associated coronal mass ejection shock, with a longitudinal semi-size of ~$20^\circ$, or by particle propagation, which could be enhanced over the field line random walk by, e.g., gyroresonant effects, or by the presence of magnetic shear between the fast and the slow streams which enhances the longitudinal spread of field lines.

Tidal Stress Triggering Mechanism of Earthquakes in Yunnan and Related Patterns of Celestial Body Positions

By calculating additional tidal stress components along seismic principle stress at focuses of 163 earthquakes in Yunnan, the mechanism of tidal stress triggering of earthquakes is analyzed. The result indicates that 62% of studied earthquakes are triggered by tidal stress. Based on this, the characteristics of related celestial body positions at the occurring time of the triggered earthquakes are studied. The distribution patterns, which have tidal-triggering physical basis, of lunar-solar ecliptic longitude differences and declinations and zenith distances are obtained. The patterns show that earthquakes in Yunnan are apt to be triggered by tidal stress during new moon and the first or third quarter of moon, the lunar-solar declinations at the occurring time of the triggered earthquakes have banded dense distribution, the average superior domain of triggered- earthquake frequency distribution against lunar-solar zenith distances are 30° ~ 140° and 20° ~ 140° respectively.

A Study of Correlation between Solar Wind Data Observed at Two Points in Interplanetary Space During the Recent Solar Maximum

Identifying co-rotating structures in solar wind enables us to predict solar wind variation at the Earth and, hence, geomagnetic disturbances. However, co-rotating structures during solar maximum are sometimes difficult to see. We correlated solar wind data obtained by two spacecraft, Nozomi heading towards Mars and ACE at the L1 point, from late 1999 through early 2002. There were intervals when the solar wind showed specific co-rotating structures even in the midst of the solar maximum, whereas no correlation was found during the other intervals. The coefficient was generally higher between Nozomi and ACE than for the 27-day recurrence at ACE, while there was some correlation, especially when the difference in longitude between the two spacecraft was less than 120°. Although frequency of occurrence of CMEs is partly responsible for the correlation, the results can be interpreted in terms of rapid changes in co-rotating high-speed streams from near-equatorial coronal holes at the solar maximum.

Transient co-orbital asteroids

We analyze the orbital behavior of four new co-orbital NEOs and the Earth horseshoe object 2002 AA29. The new objects are 2001 CK32, a 3753 Cruithne-like co-orbital of Venus, 2001 GO2 and 2003 YN107, two objects with motion similar to 2002 AA29. 2001 CK32 is on a compound orbit. The asteroid reverses its path when the mean longitude difference is −50°. Its motion is chaotic. 2001 GO2 is an Earth HS orbiter with repeated transitions to the QS phase, the next occurring 200 years from now. The HS libration period is 190 years and the QS phases last 45 years. For 2002 AA29, our simulations permit us to find useful theoretical insights into the HS–QS transitions. Its orbit can be simulated with adequate accuracy for 4400 years into the future and 1483 years into the past. The new co-orbital 2003 YN107 is at present an Earth QS. It has entered this phase in 1997 and will leave it again in 2006, completing one QS cycle. Like 2002 AA29, it has frequent transitions between HS and QS. One HS cycle takes 133 years.

One to One Resonance at High Inclination

We report results from long term numerical integrations and analytical studies of particular orbits in the circular restricted three-body problem. These are mostly high-inclination trajectories in 1 : 1 resonance starting at or near the triangular Lagrangian L5 point. In some intervals of inclination these orbits have short Lyapunov times, from 100 to a few hundred periods, yet the osculating semi-major axis shows only relatively small fluctuations and there are no escapes from the 1 : 1 resonance. The eccentricity of these chaotic orbits varies in an erratic manner, some of the orbits becoming temporarily almost rectilinear. Similarly the inclination experiences large variations due to the conservation of the Jacobi constant. We studied such orbits for up to 109 periods in two cases and for 106 periods in all others, for inclinations varying from 0° to 180°. Thus our integrations extend from thousands to 10 million Lyapunov times without escapes of the massless particle. Since there are no zero-velocity curves restricting the motion this opens questions concerning the reason for the persistence of the 1 : 1 resonant motion. In the theory sections we consider the mechanism responsible for the observed behavior. We derive the averaged 1 : 1 resonance disturbing function, to second order in eccentricity, to calculate a critical inclination found in the numerical experiment, and examine motion close to this inclination. The cause of the chaos observed in the numerical experiments appears to be the emergence of saddle points in the averaged disturbing potential. We determine the location of several such saddle points in the (φ, ω) plane, with φ being the mean longitude difference and ω the argument of pericentre. Some of the saddle points are illustrated with the aid of contour plots of the disturbing function. Motion close to these saddles is sensitive to initial conditions, thus causing chaos.

Structure Distribution of NmF2 during a Geomagnetically Quiet Period

AbstractUsing data from 48 ionosondes in the Northern Hemisphere and the model of IRI‐90, the latitude profiles of variations of NmF2 on Jan. 7, 1985 at sunspot minimum are investigated. The results show that in the equatorial anomaly F2 layer the “fountain effect” is the strongest at the Asia region and the “northern crest” in the range 20°N~30°N is the highest with a maximum value of NmF2 at noon, or a bit later. In the range of 30°N~50°N the F2 peaks decrease gradually and the peak times move to 10:00LT, while in the high latitude region (50°N~62°N) two peaks appear around noon, followed by a valley at dusk and the peak values increase again during the night. There are very few ionosondes at low latitudes in the European and American regions. Nevertheless, using the model of IRI‐90, it can be still found that the northern “crest” produced by the “fountain effect” is the weakest at longitude 270°N. The decreasing of daytime F2 peaks at higher latitudes is not evident in these regions. It means that the longitude change of latitude profiles of NmF2 diurnal variations is obvious. On the other hand, analysis of data measured by ionosondes in China and Japan (in a narrower range of longitude) shows that NmF2 diurnal variations in the region of 90°N~140°N has no great longitude difference, or so‐called longitude effect, at the “crest” region 20°N~30°N. However, at middle latitudes (30°N~50°N) the variation amplitudes of NmF2 are larger and steeper in the west China than that in the east of China and Japan.