Eclipse Research Articles

Ground-based exploration of the outer Solar system by serendipitous stellar occultations★

Serendipitous stellar occultation technique provides a powerful and unique tool to probe the outer Solar system matter, e.g. Kuiper disc and Oort cloud. We present the results of a serendipitous occultation observation campaign carried out with ULTRACAM, mounted on the ESO-VLT telescope, during 2005 May 17–20. The data are processed using the variability index (VI) method modified. The two-colour data set and the VI method allow searching for occulting objects in term of their distance (50, 200 and 5000 au). The analysis of ∼34 star-hours provide a working data set for assessing an instrumental approach to search for occultation events by trans-Neptunian objects. We performed recovery tests by implanting synthetic profiles in the data and defining the size of detectable objects to achieve a detection rate of 100 per cent. We propose a Fast Multi-Object Photometer (F-MOP) mounted on a 8-m class telescope and examine its performances. Such instrumental approach from the ground is able to exploit the occultation method for the exploration of the trans-Neptunian region, with a high efficiency.

Eclipsed Acetaldehyde as a Precursor for Producing Vinyl Alcohol

The MP2 and DFT/B3LYP methods at 6-311++G(d,p) and aug-cc-pdz basis sets have been used to probe the origin of relative stability preference for eclipsed acetaldehyde over its bisected counterpart. A relative energy stability range of 1.02 to 1.20 kcal/mol, in favor of the eclipsed conformer, was found and discussed. An NBO study at these chemistry levels complemented these findings and assigned the eclipsed acetaldehyde preference mainly to the vicinal antiperiplanar hyperconjugative interactions. The tautomeric interconversion between the more stable eclipsed acetaldehyde and vinyl alcohol has been achieved through a four-membered ring transition state (TS). The obtained barrier heights and relative stabilities of eclipsed acetaldehyde and the two conformers of vinyl alchol at these model chemistries have been estimated and discussed.

Dosimetric study of volumetric intensity-modulated arc therapy and fixed field intensity-modulated radiotherapy for cervix cancer

Objective To compare the dosimetry characteristics of volumetric intensity-modulated arc therapy (VIMAT) and fixed field intensity-modulated radiation therapy (FF-IMRT) for cervix cancer.Methods CT images of 13 patients with cervix uteri cancer were transferred into Eclipse planning system.FF-IMRT and VIMAT plans were optimized on an Eclipse treatment planning system using beam data generated for Varian trilogy linear accelerator.Planning target volume (PTV) and organs at risk were evaluated with dose-volume histogram.To appraise the difference between the techniques,the paired t-test was applied.Results Compared with the FF-IMRT plans,PTV95％ coverage of VIMAT plan group increased (t =9.84,P =0.000),PTV110％ became lower (t =-3.72,P =0.003),Dmax decreased (t =-3.51,P=0.005),and CI became worser (t=5.39,P=0.000).PTV105％,Dmean,and HI had no difference (t =-0.02,-0.60,1.13,P =0.842,0.560,0.283).V30 of the bladder was reduced by about 10％ (t =-4.99,P =0.000),and Dmean and Dmax were 1.4 Gy and 1.5 Gy lower respectively (t =-3.65,-18.03,P =0.004,0.000) ;V40 of the rectum was reduced by about 10％ (t =-2.99,P =0.012),and Dmean and Dmax were reduced by 0.6 Gy,0.8 Gy respectively (t =-2.98,-4.05,P =0.013,0.002) ;V30,V40 and V50 of the small intestine were reduced by 16％,10％ and 11％ (t =-10.85,-4.74,-8.66,P =0.000,0.001,0.000),and Dmax was reduced by 0.8 Gy (t =-9.45,P =0.000) ; V30,V40 and V50 of the bone marrow were reduced by 26％,19％ and 16％ (t =-22.10,-10.19,-4.04,P =0.000,0.000,0.002),and Dmean reduced by 1.9 Gy (t =-16.21,P =0.000) ; D5 of the left and right femoral heads were reduced by 1.6 Gy and 2.7 Gy (t =-2.89,-6.22,P =0.015,0.000).Dmax of the caudate equine was reduced by 1.5 Gy (t=-4.80,P=0.001).V20,V30,V40 and V50 of the body were reduced by 18％,18％,4％ and3％(t=-7.52,-11.75,-6.26,-6.94,P=0.000,0.000,0.000,0.000).Dmean and Dmax of the body decreased by 1.0 Gy and 0.4 Gy (t=-3.72,-3.51,P=0.000,0.005).Average machine unit (MU) decreased by 57％ (t =-40.54,P =0.000).Conclusions cervical cancer Patients with VIMAT technology can get equivalent or superior dose distribution compared with the FF-IMRT technology.And VIMAT technology could reduce MU.But the efficacy needs further clinical evaluation Key words: Cervix neoplasms/radiotherapy; Radiotherapy,fixed field intensity-modulated; Radiotherapy,volumetric modulated; Dosimetry

1-(Ferrocen-1-ylmethyl)-3-methylimidazol-3-ium iodide

The structure of the title compound, [Fe(C5H5)(C10H12N2)]I, consists of a 1-(ferrocen-1-ylmeth­yl)-3-methyl­imidazolium cation which is counter-balanced by an iodide anion. The cyclo­penta­dienyl (Cp) rings of the ferrocene unit have a slightly staggered conformation skewed from an ideal eclipsed conformation by an angle of 3.5 (6)°. The inter­planar angle between the Cp and the imidazole ring is 67.94 (2)°.

Albedo and atmospheric constraints of dwarf planet Makemake from a stellar occultation

Pluto and Eris are icy dwarf planets with nearly identical sizes, comparable densities and similar surface compositions as revealed by spectroscopic studies. Pluto possesses an atmosphere whereas Eris does not; the difference probably arises from their differing distances from the Sun, and explains their different albedos. Makemake is another icy dwarf planet with a spectrum similar to Eris and Pluto, and is currently at a distance to the Sun intermediate between the two. Although Makemake's size (1,420 ± 60 km) and albedo are roughly known, there has been no constraint on its density and there were expectations that it could have a Pluto-like atmosphere. Here we report the results from a stellar occultation by Makemake on 2011 April 23. Our preferred solution that fits the occultation chords corresponds to a body with projected axes of 1,430 ± 9 km (1σ) and 1,502 ± 45 km, implying a V-band geometric albedo p(V) = 0.77 ± 0.03. This albedo is larger than that of Pluto, but smaller than that of Eris. The disappearances and reappearances of the star were abrupt, showing that Makemake has no global Pluto-like atmosphere at an upper limit of 4-12 nanobar (1σ) for the surface pressure, although a localized atmosphere is possible. A density of 1.7 ± 0.3 g cm(-3) is inferred from the data.

A retrospective look at short-season soybean cultivar development in Ontario

Cober, E. R. and Voldeng, H. D. 2012. A retrospective look at short-season soybean cultivar development in Ontario. Can. J. Plant Sci. 92: 1239-1243. Canadian soybean production has increased from about 63 000 ha in 1951 to 1.2 million ha in 2006 with expansion from southern Ontario to shorter season areas. From 1971 to 2000, soybean production in Ontario increased sixfold. Using annual reports from 1971 to 2000 of short-season trials in Ontario, we found that the number of reported cultivars remained between three and five until 1984 when the number of cultivars started to increase at the rate of about 2.5 yr-1. The amount of time that cultivars remained in the reports has declined from 12 to 4 yr on average over the 30-yr period. Long-lived cultivars, however, were developed throughout the period including: Hardome, Merit, Evans, Maple Arrow, Bicentennial, Maple Glen, KG 41, OAC Eclipse, 9071, OAC Bayfield, PS 36, and S03-W4. Over the 30-yr period of cultivar testing, short-season seed yield increased a...

Early Chinese Observations of Occultations of Planets by the Moon

1. INTRODUCTIONAmong the numerous observations of celestial phenomena recorded in Chinese history are many allusions to occultations of planets by the Moon. In most cases the exact dates are reported. As is also true for eclipses, the accuracy and reliability of these observations can be readily tested using modern astronomical computations. Chinese records of eclipses have been extensively studied in recent years - notably for their importance in investigating Earth's past rotation.1 However, observations of the Moon's obscuring planets reported in these same sources have so far attracted relatively little attention.The earliest extant Chinese account of an occultation of a planet by the Moon dates from 69 b.c.: in the Former Han dynasty. On this occasion, the Moon was said to have eclipsed Mars. In later Chinese history, numerous similar events involving one or other of the five bright planets (Mercury, Venus, Mars, Jupiter and Saturn) are described. Until the end of the Yuan dynasty (a.D. 1367), the main sources of these observations are the astronomical treatises (usually termed tianwenshi) in the official dynastic histories (zhengshi). However, during the succeeding Ming and Qing dynasties the available sources are more varied. In addition to the dynastic histories, these later compilations include the extensive Ming shilu (Veritable records of the Ming Dynasty), and also many fangzhi or local gazettes.In the present paper we have investigated the reliability and accuracy of the reports of lunar occultations of planets as cited in the astronomical treatises of the various dynastic histories down to the end of the Yuan dynasty. We have concentrated specifically on those reports for which an exact date is given: year of the appropriate imperial reign period, lunar month and day of the sexagenary cycle. (N.B. On one occasion, in a.D. 220, the day of the lunar month is specified rather than the cyclical day.) The observations range in date from 69 b.c. to a.D. 1342.2. AIMS OF THIS STUDYIn translating and analysing the various Chinese texts relating to occultations of planets by the Moon, we have had several goals. Our primary aims have been twofold: to investigate (i) the reliability with which the dates of these events are recorded; and (ii) the precision with which the individual observations were made. This has entailed detailed comparison of the various records with the results of modern retrospective computation.Unlike solar eclipses, which almost invariably occur on the first or last day of the month on the Chinese luni-solar calendar, occultations of the outer planets Mars, Jupiter and Saturn by the Moon can occur at any time in the month. Although the dates of similar events involving Venus are more restricted, they can take place within a period of about a week around the beginning and end a lunar month. (Mercury is never far from the Sun, and occultations of this planet are only rarely recorded.) Hence comparison of the reported dates of occultations with their computed equivalents should provide a useful - although indirect - indication of the likely reliability of the dates of certain other important celestial events noted in the astronomical chapters of the same histories. These latter events, which can also occur at any time of the lunar month, include comets, novae, meteors, aurorae, and sunspots. The dates of phenomena such as these can only rarely be verified by retrospective computation and in most cases they have to be simply taken on trust.In describing an occultation, three separate astronomical terms are almost exclusively used in Chinese texts. We have investigated whether these expressions prove to be consistently precise - implying that the Moon indeed passed in front of the specified planet - or whether they were more loosely applied. An item of further concern in the present paper is the approximate time of night when the calendar date was changed for astronomical purposes. …

SCIAMACHY lunar occultation water vapor measurements: retrieval and validation results

Abstract. SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) lunar occultation measurements have been used to derive vertical profiles of stratospheric water vapor for the Southern Hemisphere in the near infrared (NIR) spectral range of 1350–1420 nm. The focus of this study is to present the retrieval methodology including the sensitivity studies and optimizations for the implementation of the radiative transfer model on SCIAMACHY lunar occultation measurements. The study also includes the validation of the data product with the collocated measurements from two satellite occultation instruments and two instruments measuring in limb geometry. The SCIAMACHY lunar occultation water vapor measurement comparisons with the ACE-FTS (Atmospheric Chemistry Experiment Fourier Transform Spectrometer) instrument have shown an agreement of 5% on the average that is well within the reported biases of ACE in the stratosphere. The comparisons with HALOE (Halogen Occultation Experiment) have also shown good results where the agreement between the instruments is within 5%. The validations of the lunar occultation water vapor measurements with MLS (Microwave Limb Sounder) instrument are exceptionally good, varying between 1.5 to around 4%. The validations with MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) are in the range of 10%. A validated dataset of water vapor vertical distributions from SCIAMACHY lunar occultation measurements is expected to facilitate the understanding of physical and chemical processes in the southern mid-latitudes and the dynamical processes related to the polar vortex.

3′-Ferrocenylcarbonyl-1′-methyl-4′-phenylspiro[indeno[2,3-b]quinoxaline-11,2′-pyrrolidine

In the title compound, [Fe(C5H5)(C31H24N3O)], the pyrrolidine ring makes a dihedral angle of 86.3 (3)° with the mean plane [r.m.s deviation = 0.074 (2) Å] of the indeno-quinoxaline ring system. The central pyrrolidine ring adopts a twist conformation and the two cyclopentadienyl rings adopt an eclipsed conformation. In the crystal, mol­ecules are linked by weak C—H⋯N and C—H⋯π inter­actions, propagating along the c and a axes, respectively.

(3aS,4S,6S,7aR)-Hexahydro-3a,5,5-trimethyl-2-phenyl-4,6-methano-1,3,2-benzodioxaborole

The mol­ecule of the title compound, C16H21BO2, comprises a chiral fused tricyclic system containing five-membered (1,3,2-dioxaborolane), six-membered (cyclo­hexa­ne) and four-membered (cyclo­butane) rings. The 1,3,2-dioxaborolane ring is almost planar (r.m.s. deviation = 0.035 Å), and the syn H and Me substituents at this ring are in an eclipsed conformation. The cyclo­hexane and cyclo­butane rings adopt sofa and butterfly conformations, respectively. The B atom has a trigonal–planar configuration (sum of the bond angles = 360.0°). The phenyl ring is practically coplanar with the 1,3,2-dioxaborolane ring [dihedral angle between the ring planes = 1.96 (8)°]. The absolute structure was determined from the known configuration of (+)-pinanediol which was used in the synthesis. In the crystal, weak C—H⋯π(Ph) inter­actions occur.

Flashbacks and Eclipses in Italian Art in the 1960s

Flashbacks and Eclipses in Italian Art in the 1960s

3-(Ferrocen-1-ylcarbonyl)-1-methyl-4-(4-methylphenyl)spiro[pyrrolidine-2,11′-indeno[1,2-b]quinoxaline

In the title compound, [Fe(C5H5)(C32H26N3O)], the pyrrolidine ring adopts a twist conformation. The indeno–quinoxaline ring system [86.44 (5)°], the methyl­phenyl ring [86.06 (7)°] and the ferrocene rings [82.00 (7) and 83.95 (9)°] are almost perpendicular to the pyrrolidine ring. The two cyclopentadienyl rings adopt an eclipsed conformation. The crystal structure features C—H⋯N inter­actions.

Photometry and models of selected main belt asteroids

Context. The shapes and spin states of asteroids observed with photometric techniques can be reconstructed using the lightcurve inversion method. The resultant models can then be confirmed or exploited further by other techniques, such as adaptive optics, radar, thermal infrared, stellar occultations, or space probe imaging. Aims. During our ongoing work to increase the set of asteroids with known spin and shape parameters, there appeared a need for displaying the model plane-of-sky orientations for specific epochs to compare models from different techniques. It would also be instructive to be able to track how the complex lightcurves are produced by various asteroid shapes. Methods. Basing our analysis on an extensive photometric observational dataset, we obtained eight asteroid models with the convex lightcurve inversion method. To enable comparison of the photometric models with those from other observing/modelling techniques, we created an on-line service where we allow the inversion models to be orientated interactively. Results. Our sample of objects is quite representative, containing both relatively fast and slow rotators with highly and lowly inclined spin axes. With this work, we increase the sample of asteroid spin and shape models based on disk-integrated photometry to over 200. Three of the shape models obtained here are confirmed by the stellar occultation data; this also allowed independent determinations of their sizes to be made. Conclusions. The ISAM service can be widely exploited for past and future asteroid observations with various, complementary techniques and for asteroid dimension determination.

The influence of forward-scattered light in transmission measurements of (exo)planetary atmospheres

The transmission of light through a planetary atmosphere can be studied as a function of altitude and wavelength using stellar or solar occultations, giving often unique constraints on the atmospheric composition. For exoplanets, a transit yields a limb-integrated, wavelength-dependent transmission spectrum of an atmosphere. When scattering haze and/or cloud particles are present in the planetary atmosphere, the amount of transmitted flux not only depends on the total optical thickness of the slant light path that is probed, but also on the amount of forward-scattering by the scattering particles. Here, we present results of calculations with a three-dimensional Monte Carlo code that simulates the transmitted flux during occultations or transits. For isotropically scattering particles, like gas molecules, the transmitted flux appears to be well-described by the total atmospheric optical thickness. Strongly forward-scattering particles, however, such as commonly found in atmospheres of Solar System planets, can increase the transmitted flux significantly. For exoplanets, such added flux can decrease the apparent radius of the planet by several scale heights, which is comparable to predicted and measured features in exoplanet transit spectra. We performed detailed calculations for Titan’s atmosphere between 2.0 and 2.8μm and show that haze and gas abundances will be underestimated by about 8% if forward-scattering is ignored in the retrievals. At shorter wavelengths, errors in the gas and haze abundances and in the spectral slope of the haze particles can be several tens of percent, also for other Solar System planetary atmospheres. We also find that the contribution of forward-scattering can be fairly well described by modelling the atmosphere as a plane-parallel slab. This potentially reduces the need for a full three-dimensional Monte Carlo code for calculating transmission spectra of atmospheres that contain forward-scattering particles.

N-(1-Azanidyl-2,2,2-trichloroethylidene)-2,2,2-trichloroethanimidamide]copper(II)

The title compound, [Cu(C4H2Cl6N3)2], was obtained by the reaction of CCl3CN with ammonia in presence of CuCl. The CuII atom is located about an inversion centre. The mol­ecule consists of three planar units (one central square CuN4 and two C2N3 fragments), adopting a staircase-like structure. The six-membered metallocycles have a sofa conformation with the Cu atom out of the plane of the 1,3,5-triaza­penta­dienyl ligands by 0.246 (5) Å. The ipso-C atoms of the CCl3 substituents are slightly out of the 1,3,5-triaza­penta­dienyl planes by 0.149 (6) and −0.106 (6) Å. The CCl3 groups of each 1,3,5-triaza­penta­dienyl ligand are practically in the energetic­ally favourable mutually eclipsed conformation. In the crystal, the mol­ecules are packed in stacks along the a axis. The mol­ecules in the stacks are held together by two additional axial Cu⋯Cl inter­actions of 3.354 (2) Å. Taking the axial Cu⋯Cl inter­actions into account, the CuII atom exhibits a distorted [4 + 2]-octa­hedral coordination environment. The stacks are bound to each other by weak inter­molecular attractive Cl⋯Cl [3.505 (2)–3.592 (3) Å] inter­actions.

First ever VLF monitoring of the lunar occultation of a solar flare during the 2010 annular solar eclipse and its effects on the D-region electron density profile

A ground based Very Low Frequency (VLF) radio receiver of Indian Centre for Space Physics located at Khukurdaha (22°27′N, 87°45′E) monitored the VLF signal at 19.8kHz from the NWC station during a partial solar eclipse (maximum obscuration 75%) which took place on January 15, 2010. The receiver and the transmitter were on two opposite sides of the annular eclipse belt. During the same period, a solar flare also occurred and it was partly blocked by the lunar disk. Thus the resultant signal was perturbed both by the eclipse and by the flare. The deviation of the signal from the normal value was obtained by subtracting from the average diurnal signal on days bracketing the eclipse. The deviation was analysed. We compare the data from GOES-14, HINODE and RHESSI satellites during the event. We got a clear depression in the data during the period of the partial eclipse. Most interestingly, there was also a flaring activity in the sun which reached its peak (C-type) just after the time when the eclipse was near maximum. By superposing the lunar disk on the image obtained by HINODE mission, we pin-point the time frame of blocking hard and soft X-rays. We extract the time variation of the electron density profile in the D-region of the ionosphere due to occulted solar flare from the combined effect of the eclipse and the flare. We also compare the results with a normal solar flare.

Establishment and application of DPO-based quadruple real-time PCR for detection of mycobacteria

Objective To establish a rapid, accurate and specific method to detect the common mycobacteria based on multiplex real-time PCR. Methods The dual priming oligonucleotide （DPO）primers and TaqMan probes labeled with FAM，ROX，HEX or JOE fluoresceins at 5′ end and eclipse at 3′ end respectively were designed to detect the 16S rRNA of mycobacteria.Both specificity and sensitivity were estimated on multiplex real-time PCR detecting genome DNA from 4 mycobacterial model species.Sixty eight early morning sputum specimens collected from hospitalized patients in the Red Cross Hospital of Hangzhou were detected by multiplex real-time PCR, bacterial culture and smear microscopy simultaneously.The positive rates were analyzed by chi-square. Results Mycobacteria including Mycobacterium tuberculosis and three common non-tuberculosis mycobacteria spp.were identified by multiplex real-time PCR accurately and specifically, with the limited load at 101 cfu/ml.In 68 sputum specimens，31 were positive (positive rate 45.6%) by this method, which was significant higher than that by smear microscopy (positive rate 14.7%, χ2=15.4,P<0.05).The positive cases were identified as 28 Mycobacterium tuberculosis, 1 Mycobacterium avium and 2 Mycobacterium intracellulare in agreement with the culture results.One case，which is detected by culture，but not by PCR，was identified as Mycobacterium chelonae by sequencing. Conclusion The multiplex real-time PCR characterizing as sensitive, specific and time-saving for Mycobacterium tuberculosis and common non-tuberculosis mycobacteria could be chosen as the rapid laboratory test of mycobacterial infection.（Chin J Lab Med,2012,35:722-725） Key words: Mycobacterium; Multiplex polymerase chain reaction; DNA primers

Saturn upper atmospheric structure from Cassini EUV and FUV occultations 1This article is part of a Special Issue that honours the work of Dr. Donald M. Hunten FRSC who passed away in December 2010 after a very illustrious career.

Stellar occultations of the Saturn atmosphere using the Cassini ultraviolet imaging spectrograph (UVIS) experiment have provided vertical structure at a range of latitudes. The transmission spectra in the extreme–far ultraviolet (EUV–FUV) range allow extraction of vertical profiles of H2 and hydrocarbon abundances from the top of the atmosphere to about 300 km above the 1 bar (1 bar = 100 kPa) pressure level. A reanalysis of the Voyager 2 δSco occultation in 1981 is consistent with the original report. The hydrocarbon homopause is near a pressure of 0.2 μbar in the UVIS analysis, compared to ∼0.01 μbar obtained from the Voyager occultation. Measured hydrocarbon abundances are obtained in the pressure range 600–0.1 μbar in the Cassini UVIS experiment. The combined UVIS results provide evidence for significant latitudinal dependence of vertical temperature profile. The confinement of the hydrocarbons in the current observations compared to published models and the Voyager ultraviolet spectrograph (UVS) results at solar maximum, infer smaller eddy diffusion coefficients in this epoch. Model calculations indicate that the latitudinal dependence of H2 vertical displacements is caused primarily by the combined effects of gravitational potential and evident differences in electron energy deposition at the top of the atmosphere affecting the temperature profile. The derived H2 density profiles from ~–40° latitude and others close to the equator, are found to be nearly identical on a pressure scale below the exobase. The inference is that that the pressure profile of H2 density at Saturn is unchanged over a broad range of latitudes.

Direct comparisons of GOMOS and SAGE III NO&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt; vertical profiles

Abstract. In this paper, we present the first global comparisons between the two unique satellite-borne data sets of nitrogen trioxide (NO3) vertical profiles retrieved from the GOMOS (Global Ozone Monitoring by the Occultation of Stars) stellar occultations and the SAGE III (Stratospheric Aerosol and Gas Experiment) lunar occultations. The comparison results indicate that between the altitudes 25 km and 45 km the median difference between these two data sets is within ± 25%. The study of zonal median profiles shows that the climatologies calculated from GOMOS and SAGE III profiles are comparable and represent the same features in all latitude bands. No clear systematic differences are observed. The median profiles are closest in the tropics and slightly deviating at high latitudes.

Propane-1,3-diammonium dichromate(VI)

The title compound, (C3H12N2)[Cr2O7], consists of a discrete dichromate anion with an eclipsed conformation and a propane-1,3-diammonium cation. Both kinds of ions have a mirror plane passing through the bridging O atom and the central methyl­ene C atom of the Cr2O7 2− and C3H12N2 2+ moieties, respectively. Anions and cations are alternately stacked to form columns parallel to the b axis. Ions are linked by intra- and inter-column hydrogen bonds of types N—H⋯O and C—H⋯O, involving O atoms of the dichromate anions as acceptors, and ammonium or methyl­ene groups as donors.