Showing papers on "Solar eclipse published in 2006"

POETS: Portable Occultation, Eclipse, and Transit System

Abstract: Occultations of stars by small bodies in the outer solar system are opportunities to make high- resolution measurements of their geometries and orbital elements and to detect or probe their atmospheres. Such events are limited in space and time, so it is desirable to deploy highly capable camera systems on multiple fixed and/or portable telescopes anywhere in the world, potentially on short notice. Similar considerations apply to planetary transits and solar eclipses. We have designed a camera system called POETS (Portable Occultation, Eclipse, and Transit System), which is optimized for occultation and related observations, and have assembled five such systems. The core of this system is the Andor Technology DV-887 (now DU-897) frame-transfercamera, featuring a high frame rate, minimal dead time, high quantum efficiency, and low read noise. An electron- multiplying mode lowers effective read noise to below 1 e ! pixel ! 1 and is capable of photon counting. Each POETS includes a compact GPS timing system with microsecond accuracy, and a high-performance computer system capable of sustained fast frame rates. Each POETS is designed to be transportable as carry-on luggage and is adaptable to a wide variety of sites. POETS were deployed for the first time for the 2005 July 11 Charon occultation event, and they performed extremely well on telescopes with apertures from 0.6 to 6.5 m. Three POETS were subsequently deployed for the 2006 March 29 total solar eclipse, and five for the 2006 June 12 Pluto occultation.

Measurements and predictions of the illuminance during a solar eclipse

Abstract: Measurements of illuminance during a solar eclipse are presented. The data are compared to theoretical predictions, based on a geometrical model for obscuration. The model assumes a straight and uniform motion of the sun and moon as well as a spherical shape of both, i.e. it neglects any effects of limb darkening. Furthermore, the sun's disk is assumed to have homogeneous luminosity, i.e. any luminosity variations due to sun spots are neglected. Input parameters are the duration of the eclipse, the duration of totality, the impact parameter, i.e. the distance between the two trajectories of sun and moon, and the sizes of sun and moon. The model applies to all types of eclipses, partial, annular and total.

Modeling the geomagnetic effects caused by the solar eclipse of 11 August 1999

Abstract: [1] The solar eclipse of 11 August 1999 was total along a belt crossing Central Europe, where there is a high density of magnetic observatories. We studied the transient geomagnetic effects produced by the temporary cutoff of the ionizing solar radiations during the eclipse. It is the first case in which the phenomenon has been analysed in a multisite context. For observatories along the umbra path, a model based on the equivalent electric current schema is proposed.

Real-world word learning: exploring children’s developing semantic representations of a science term

Abstract: Assessments of lexical acquisition are often limited to pre-school children on forced choice comprehension measures. This study assessed the understandings 30 school-age children (mean age = 6;7) acquired about the science term, eclipse following a naturalistic exposure to a solar eclipse. The knowledge children acquired about eclipses and a control term, comet was assessed at three points in time (baseline-test, two-week post-test and five-month post-test) using a range of assessment tasks (multiple-choice comprehension, picture-naming, drawing and a model of a solar system task). Children's knowledge was compared to 15 adult controls during the baseline-test and two-week post-test. Children acquired extensive knowledge about eclipses, but not comets; at the two-week post-test and five-month post-test, the majority of children named and drew eclipses and „made? an eclipse using models of the sun, moon and earth. Also, children's eclipse knowledge more closely approximated adult-level understandings at the two-week post-test than at the baseline-test. Implications for the study of lexical acquisition in later development are discussed.

The April 8, 2005, Eclipse White-Light Corona

Abstract: The hybrid solar eclipse of April 8, 2005, provided a good opportunity to observe the white-light solar corona, even though the eclipse lasted just 30 seconds and could be seen only from ships in the Pacific Ocean. During the eclipse, we detected a unique ‘cloud’ of particles in the white-light corona above the west limb ≈260°–270°. We compare this feature with EUV images from SOHO. The feature’s density and temperature seem comparable to a coronal condensation, and, like a coronal condensation, it is connected to the emergence of material from the solar surface without a flare. However, the morphology of the feature shows clear differences from a classical coronal condensation.

Variations of solar radiation at the Earth's surface during the total solar eclipse of 29 March 2006

Abstract: On 29 March 2006, a total eclipse of the Sun was visible on the Greek island Kastelorizo (36.150°N, 29.596°E). An extended set of instruments was installed in order to measure the variability of different components of the radiation field during the eclipse. Seven spectroradiometers (two scanning double monochromators measuring especially in the UV range, 4 photo diode array instruments and one CCD-spectrograph for the UV and visible wavelength range) performed measurements during 28 and 29 March. A narrow band multi-filter radiometer and two broadband erythemal and UVA radiometers were operated with about 1 sec temporal resolution. Two sun-photometers were used to measure ozone column and aerosol optical depth. The weather conditions on March 28 were almost perfect, whereas on 29 March thin cirrus clouds were occasionally present in front of the sun. Details about the observed changes in the radiation field on the eclipse day are presented and compared with model calculations of the change in extraterrestrial solar irradiance. The results show an underestimation of the model calculations compared with measurements, with respect to the effect of the limb darkening on the spectral behavior of the solar irradiance during the eclipse. The absolute changes in the global and direct irradiance and their wavelength dependencies are discussed. Finally, the decrease in total ozone retrieved during the course of the eclipse from direct irradiance measurements is investigated with respect to the effect of the limb darkening and the influence of the diffuse radiation entering the field of view of the Brewer spectroradiometer.

Optical coherence tomography in solar eclipse retinopathy

Abstract: CASE REPORT We describe the case of a patient suffering from acute visual loss soon after watching a solar eclipse. Optical coherence tomography was the main diagnostic tool used. DISCUSSION Solar retinopathy is now an unusual cause of visual loss, although there are still some cases diagnosed, especially after viewing solar eclipses. Optical coherence tomography is suitable for detecting permanent retinal injuries related to solar exposure, with the outer retinal layers being typically affected.

A confirmation of the Allais and Jeverdan-Rusu-Antonescu effects during the solar eclipse from 22 September 2006 , and the quantization of behaviour of pendulum

Abstract: The experiments made with a paraconical pendulum at Suceava Planetarium (Romania) during annular solar eclipse from 22 September 2006 confirm once again the existence of the Allais effect (change of speed of rotation of plane of oscillation of a pendulum during an eclipse ) and Jeverdan-Rusu-Antonescu effect ( change of period of oscillation of a pendulum during an eclipse) Also is take in evidence the existence of the quantization of the azimuth of plane of oscillation of a pendulum which can be treated as a quantum oscillator. A large number of the excited states for a quantum Foucault pendulum are doubly degenerate in a similar way as the time dependence of the azimuths for a paraconical pendulum with a high sensitivity. The quantum eigenstates for a large energy of a Foucault pendulum predict that the probability density of finding the particle is largest near the classical trajectories. Although the annular solar eclipse from 22 September 2006 was not optical visible from Romania, a gravitational perturbation was detected with a sensitive paraconical pendulum and leds to ideia that gravitational perturbations who occur during an eclipse are similarly with tide when the Moon are at antimeridian .

Disturbances in the ionosphere and atmosphere caused by the solar eclipse of August 11, 1999

Abstract: Results of comparing ionospheric radio noise at wavelength of 2 m at midlatitudes to the data of the ionospheric vertical sounding during the partial phase of the solar eclipse of August 11, 1999, are presented. Disturbances in the ionospheric layers, radio noise of the ionospheric plasma, and variations and fluctuations in the atmospheric pressure at the Earth surface during the eclipse are considered. The parameters of the Lamb wave, which propagated with velocity of 300 m/s from the region of the total phase of the eclipse are determined. The Lamb wave characteristics in the summer midlatitude and auroral ionosphere have been compared.

British observations of the 1868 total solar eclipse from Guntoor, India

Abstract: The total solar eclipse of 1868 August 17/18 was observed in both India and Thailand. One Indian expedition was sponsored by the Royal Astronomical Society, and led by Major J.F. Tennant. In this paper we describe the observing team and instruments, discuss their observations, and conclude with some remarks on the place of the 1868 eclipse in solar studies and later nineteenth century European astronomical expeditions to India.

Gravitation experiments during the total solar eclipse

Abstract: The variations of the apparent vertical direction of the gravity field were measured with horizontal gravimeters acting as tilt meters during the total solar eclipse in Turkey in March 29, 2006. Three separated locations within the path of totality were chosen for observations, two spaced apart along the center line, and one off the center line. No anomaly was observed at the furthest location from the center line. Aperiodic oscillations in tilt were recorded at the two locations on the center line. These may be related to the eclipse phenomenon. The average tilt amplitude deviation during the eclipse over all locations and in all directions was 150 nrad, which can be regarded as a mean upper limit for the eclipse related changes in the tilt.

Ionospheric response to the solar eclipse on March 29, 2006

Abstract: In the present work, results of vertical sensing of the ionosphere at the Klyuchi (Novosibirsk) and Arti (Ekaterinburg) Geophysical Observatories during the solar eclipse on March 29, 2006 are given. The maximum eclipse was observed in Novosibirsk at 11:43 UT; the obscuring phase was 92%. A maximum obscuring phase of 80% was observed at the Arti Georhysical Observatory at 11:32 UT. The results obtained are compared with the analogous data obtained in the preceding and next days as well as with the data of many-year observations on March 28, 29, and 30. The results obtained demonstrate that the eclipse affects most strongly the characteristics of the F layer. The maximum variations of the critical frequency f0F2 were delayed by about 10 min from the maximum eclipse phase, relaxation started half an hour after the maximum eclipse phase, and the frequency decreased at most by 1.5 MHz. A decrease in the critical frequency of the F1 layer has a greater delay and smaller amplitude. The results obtained are in good agreement with previous measurements.

Propagation related measurements during three solar eclipses in Turkey

Abstract: In this work, we would like to report three different measurements in the years of 1976, 1999, and 2006, relevant to the ionospheric radio propagation They are different in temporal and spatial coordinates During the recent total solar eclipse on 29 March 2006, High Frequency (HF) signals are received in Antalya (369 °N, 307 °E), Turkey The channel occupancy and Atmospheric Noise Measurements over the HF band before, during, and after the solar eclipse are obtained

Influence of a solar eclipse on Doppler frequency shift of signal from upper atmosphere

Abstract: The Doppler shift frequency (DSF) method and based on it the interference goniometric techniques are effectively applied in ionospheric researches [1-3]. The long-time continuous measurements are required for research the ionospheric processes and rare events, such as solar flashes and solar eclipses. In this article we present the results of measurements which were spent in measuring equipment "Spectr" of Kazan University.

Astronomical Dating of Babylonian Texts Describing the Total Solar Eclipse of S.E. 175

Abstract: The Late Babylonian astronomical texts (LBAT) are of considerable astronomical and historical importance. For instance, some of the earliest reliable sightings of Halley's Comet (in both 164 and 87 B.C.) are recorded on the LBAT. Furthermore, the numerous lunar and solar eclipses that these cuneiform tablets report have proved of great value in the investigation of Earth's past rotation.' Several texts have also proved important in dating historical events such as the deaths of Xerxes and Alexander the Great. Virtually all of the LBAT were recovered from the site of Babylon in the l870s and l880s and are now mostly in the British Museum. Some three thousand texts are preserved, most of which are very fragmentary; regrettably, very few tablets were carefully excavated, leading to considerable damage. The LBAT can be divided into two main groups: non-mathematical texts, which are much more numerous; and texts that are mainly devoted to mathematical astronomy. It is the former group that concerns us here. Most of the LBAT that contain observations can be divided into three distinct categories: astronomical diaries; compilations of reports of a specific type of phenomenon; and so-called 'goal-year texts\".' We shall briefly consider each type of tablet. Diaries form the prime source.' Originally covering the whole date range from around 750 B.C. to perhaps as late as A.D. 100, each individual text contained a detailed record for six or seven months of many types of phenomena: for instance, lunar and solar eclipses, conjunctions of the Moon and planets with stars, and planetary first and last visibilities and stationary points. The bulk of the material in a diary was observational, but predictions of certain events e.g. eclipses are also included. Most surviving diaries range in date from around 380 B.C. to 50 B.C. The Babylonian astronomers also assembled compilations of reports of individual phenomena from the diaries.' These texts sometimes cover several centuries. Socalled 'goal-year texts' were also compiled from the diaries.\" Probably intended for use in predictions, these contain lunar and planetary data from specified intervals before a selected date: the goal-year. For instance, Venus data are cited from 8 years previously and lunar data from 18 or 19 years prior to the goal-year. Although both compilations and goal-year texts are often severely damaged, they frequently contain information that has been lost from the diaries. The Babylonians counted years from either the start of a king's reign or the Seleucid Era (311 B.C.); however, some late texts also use the Arsacid Era (246 B.C.) in parallel.

Earth-Moon-Sun System: Eclipses Models

Abstract: Everybody understands what is meant by an eclipse: a body that covers another one. However, the general audience and the students in particular do not know exactly "What the relative positions of the Earth, the Sun and the Moon have to be in order for an eclipse to take place?" You can read a newspaper or watch TV and observe that the information about an eclipse is not correct. In my country, it was stated, in a very important newspaper, that "the solar eclipse will take place tomorrow because there will be a Full Moon". Teaching this topic in schools or in educational sessions in observatories, it is a good idea to introduce a simple model that maintains the proportion between the diameters and distances of these three bodies. This contribution will introduce this model, showing their applications in the playgrounds of the school, for sunny days or in the classroom for cloudy days.

Polarization at the extreme limb of the sun and the role of eclipse observations

Abstract: Scattering of light in the Sun's atmosphere produces polarization throughout the solar spectrum. Due to the changing scattering geometry this polarization increases monotonically from disk center towards the solar limb. Many different factors influence the magnitude of the polariza- tion: The intrinsic polarizability of the scattering atomic system (combination of angular momenta and nuclear spin for the involved atomic levels, quantum interferences and optical pumping), colli- sional processes and depolarizing magnetic fields, the ratio between line and continuum opacities, anisotropies of the radiation field, small-scale structuring of the atmosphere (deviations from plane- parallel stratification), etc. As all these effects vary greatly from line to line, the linearly polarized spectrum becomes richly structured, in a way that has little resemblance to the structuring of the intensity spectrum. According to a classic solution by Chandrasekhar for an idealized, purely scattering plane-parallel atmosphere the linear polarization reaches asymptotically at the extreme limb the very high value of 11.7%. Measurements a few arcsec inside the limb show much smaller polarization values, generally much below 1%, and in most cases less than 0.1%. The polariza- tion amplitude is however expected to increase dramatically at the extreme limb, within the last arcsec, and could possibly approach the Chandrasekhar limit in some spectral lines. Observations of this increase have not been possible in the past due to seeing effects in the Earth's atmosphere, telescope resolution, and stray light in the instrument. All these limitations can be avoided at a total solar eclipse, when the edge of the Moon is used as a knife edge to isolate the extreme limb from the glaring radiation of the solar disk, to allow us to record the polarization from the separate height layers of the atmosphere, from the photosphere through the chromosphere. This has to be done during the brief flash phase of the eclipse (the transition to totality at second contact, or the emergence from totality at third contact). The polarization of the flash spectrum has never been successfully recorded in the past but is being done by a Swiss team from ETH Zurich during the 29 March 2006 eclipse at Waw an Namos, Libya.

Polarization properties of the June 21, 2001 solar corona

Abstract: Five series of coronal images have been obtained by V.Kulijanishvili during the total solar eclipse of the June 21, 2001, in Zambia, Lusaka. A photographic mirror-lens coronagraph- polarimeter (D=100 mm, F=1000 mm) was used. The absolute brightness, polarization and direction of polarization of the inner corona were measured. Standard techniques are used for the separation of the F- and K-coronas and for determination of coronal electron densities and temperatures. The background skylight polarization and intensity are calculated.

Radio waves recorded in belgrade

Abstract: VLF (Very-Low-Frequency, 3-30 kHz) radio waves emitted from four single frequency transmitters located in Australia, USA, UK and Italy, have been permanently monitored in Belgrade by an AbsPAL receiver since August 2003. The collected data com- prise a digitalized VLF wave amplitude and phase both recorded at 0.1 s time intervals for each of the four transmitters. Peculiarities, showing up in proles of their time depen- dence curves, reveal eects of phenomena such as solar ares and magnetospheric electron precipitations among others. These features of solar activity may signican tly inuence the electron density distribution in the ionospheric D-region and consequently the characteristics of received radio signals. This work gives some insight into solar activity and space weather in general in their signatures in VLF signal recordings as well. Two examples show how sudden changes in the ionizing solar X-ray intensity in the ionosphere caused by a are and solar eclipse, eect VLF signals recorded by the Belgrade receiver.

Photometric and Spectrometric Investigations of the Solar Corona and Atmospheric Effects during the forthcoming March 29, 2006 Total Solar Eclipse

Abstract: A great part of the information about large-scale structure of the solar corona comes from solar observations during total solar eclipses. Space coronagraphs over-occult the Sun, omitting from view exactly the inner and coronal reasons well imaged at total solar eclipses. The total eclipse of the Sun on 2006 March 29, will be visible from within a narrow corridor, which transverse half the Earth. We foresee observations from the territory of Turkey. The aims of observations are: Photometric investigation of the White corona structure and polarization; Investigation of the structure of monochromatic emission corona in green (Fe XIV, λ=5303Ǻ) and red (Fe X, λ=6374Ǻ) line, Hα, and the thermal corona in the 2÷5 µm region of the Infrared spectrum; Tropospheric and stratospheric O3 and NO2 photochemistry study; Determining of the dynamics of basic microclimatic parameters of the 10 m ground atmospheric layer. The following methods will be used: Taking of photograph of the corona (telescope-refractor 100/1000mm, spectrozonal photoemulsions, polarization and infrared barrier filters), registration of the investigated emissions (telescope-refractor 150/1600mm, high sensitive photo-emulsions, narrow band filters), Differential Optical Absorption Spectroscopy method, measuring of the microclimatic parameters with automatic meteorological station; processing and analysis of the photographs and data, seeking for wave structures in the O3 and NO2 concentration, comparison with other measurements during an eclipse. The results we expect are: Determining of the Solar corona characteristics, finding of regularities in the O3 and NO2 behavior in conditions of reduced solar radiation, and clarifying the dynamical and photochemical processes in the stratosphere and climate of the ground atmosphere.

Effect of partial solar eclipse on the behaviour of solar cell parameters

Abstract: The performance of the solar cell is influenced by the spectral solar distribution. The silicon solar cell spectral response does not totally coincide with the solar spectrum. In the case of sun light exposure at outdoor conditions, the shapes of the cell spectral response curves are slightly different than that of under simulated light exposure. This paper is interested in studying the effect of variation of solar radiation during the partial eclipse on the output short circuit current and open circuit voltage of the monocrystalline and amorphous silicon solar cells. Also, the spectral cell behaveiour in terms of the solar eclipse was investigated. The ultimate goal is to explain some of an interesting natural phenomenon by using the solar cell spectral response.