Absolute Calibration of the Clementine UVVIS Data: Comparison with Ground-Based Observation of the Moon

Calibrated Clementine images of the Moon and data from Pieters's absolutized spectrophotometric catalog are compared. The scales of these two photometric systems are shown to differ greatly: the albedo of the lunar surface at a phase angle of 6° determined from the Clementine data turns out to be a factor of 2.5 higher than that inferred from ground-based photometry. The fact that the lunar-soil samples from the Apollo 16 landing site used for absolute calibration of the Clementine data are not representative may be responsible for the differences between the scales. Maps are constructed (for wavelengths of 0.42, 0.75, and 0.95 m), which reproduce the distribution of the ratio of the brightnesses determined from telescopic images of the visible lunar hemisphere and from the corresponding Clementine mosaics. The comparison shows fairly good agreement in the details. On the average, the differences are about 10%. The streakiness of the Clementine mosaics are clearly seen in the maps, which is attributable to a low quality of the photometric joining of the data from two one-month imaging series.     

Analysis of Lunar Terrain Altitudes and Correlation Links between the Terrain and Gravitational Field; Preliminary Conclusions on the Global Density Inhomogeneities of the Lunar Crust

The harmonic and statistical analysis of lunar terrain altitudes has been performed based on the procedure developed by the authors. The explanations for the displacements of the Moon's figure relative to the center of mass and for the shift of the major equatorial axis relative to the earthward direction have been given. The maps have been plotted for the density anomalies in the near-surface layers of the Moon that correspond to mascons (with negative correlation between the field and terrain mainly for N= 10, 11) and other variants of links between the gravitational field and terrain (with positive correlation between the field and terrain). It has been shown that the harmonics of the degree N= 5–9 mainly correspond to the isostatic compensation of the terrain in the near-surface layers of the crust; the low harmonics (N< 5) correspond to the isostatic compensation of the terrain in the deeper layers, while the harmonics of the degrees N > 11 may indicate the presence of tension in the crust generated by small structures of the terrain. Based on the maps, possible locations of deposits of volatile elements (mainly on the far side of the Moon and in the northern cir-cumpolar region) and other natural resources have been determined.

     

Lunar X-ray fluorescence observations by the Chandrayaan-1 X-ray Spectrometer (C1XS): Results from the nearside southern highlands

The Chandrayaan-1 X-ray Spectrometer (C1XS) flown on-board the first Indian lunar mission Chandrayaan-1, measured X-ray fluorescence spectra during several episodes of solar flares during its operational period of ∼9 months. The accompanying X-ray Solar Monitor (XSM) provided simultaneous spectra of solar X-rays incident on the Moon which are essential to derive elemental chemistry. In this paper, we present the surface abundances of Mg, Al, Si, Ca and Fe, derived from C1XS data for a highland region on the southern nearside of the Moon. Analysis techniques are described in detail including absolute X-ray line flux derivation and conversion into elemental abundance. The results are consistent with a composition rich in plagioclase with a slight mafic mineral enhancement and a Ca/Al ratio that is significantly lower than measured in lunar returned samples. We suggest various possible scenarios to explain the deviations.     

Computer Simulation of Sputtering of Lunar Regolith by Solar Wind Protons: Contribution to Change of Surface Composition and to Hydrogen Flux at the Lunar Poles

A computer simulation of the sputtering of lunar soil by solar wind protons was performed with the TRIM program. The rate of the sputtering-induced erosion of regolith particles was shown to be less than 0.2 Å per year. A preferential sputtering of Ca, Mg, and O was found along with a less intense sputtering of Fe, Si, and Ti. However, with no other selection mechanisms, surface concentrations of the atoms would differ from the volume ones by no more than 6 %. The enrichment of rims of regolith particles with iron occurs as a result of selective removal of lighter atoms from the lunar surface because of different energies of escape from the Moon's gravity. The energy distributions proved to be the same for all sorts of the sputtered atoms, except for implanted hydrogen; thus, a greater fraction of the atoms left on the lunar surface corresponds to heavier elements. According to simulation results, the concentration of reduced iron observed in the mature regolith could be attained during the time of regolith particle exposure to the present flux of solar wind (10⁵ years). Thus, sputtering can provide the concentration of Fe₀ observed in regolith. On periphery of a cloud of impact vapor the temperature is too low for an irreversible selective removal of evaporation products; thus, a meteoritic bombardment contributes to the formation of composition of the rims of regolith particles mainly through enrichment of the rims with elements from the bulk of the particles. The estimates of fluxes of backscattered solar wind protons and of sputtered protons, earlier implanted to the regolith, demonstrated that their contribution to the proton flux near the poles is only 10⁴ cm^–2 s^–1. This is by two orders of magnitude smaller than the proton flux from the Earth's magnetosphere which is, therefore, the main source of protons for permanently shaded polar craters of the Moon.     

Lunar meteorite LaPaz Icefield 04841: Petrology,texture, and impact‐shock effects of a low‐Ti mare basalt

Abstract— Found during the 2004 U.S. Antarctic Search for Meteorites season, LaPaz Icefield (LAP) 04841 represents an addition to the LaPaz lunar basalts suite and brings the total mass collected to 1.93 kg. The presence of FeNi grains, troilite, and the anorthositic composition of plagioclase are evidence for the lunar origin of this meteorite. Pyroxene and olivine Mn/Fe values plot along the trend set for lunar basalts. Analyses of chromite grains provide a V/(Al + Cr) ratio of 1.33 ± 13, translating to an fO₂ one log unit below the IW buffer, in accordance with previous fO₂ estimates for lunar basalts. Application of the Zr‐cooling speedometer, for ilmenite and ulvöspinel pairs, gives a cooling rate of 5.2 °C/day, matching previous estimates of cooling rates for the LaPaz lunar meteorites and Apollo mare basalts. Mineral modes and chemistries, as well as trace‐element patterns, provide compelling evidence for pairing of this meteorite to others in the LaPaz lunar basalt suite.     

Description of atmospheric conditions at the Pierre Auger Observatory using the Global Data Assimilation System (GDAS)

Atmospheric conditions at the site of a cosmic ray observatory must be known for reconstructing observed extensive air showers. The Global Data Assimilation System (GDAS) is a global atmospheric model predicated on meteorological measurements and numerical weather predictions. GDAS provides altitude-dependent profiles of the main state variables of the atmosphere like temperature, pressure, and humidity. The original data and their application to the air shower reconstruction of the Pierre Auger Observatory are described. By comparisons with radiosonde and weather station measurements obtained on-site in Malargüe and averaged monthly models, the utility of the GDAS data is shown.     

Statistical Analysis of the Links among Lunar Mare Soil Mineralogy, Chemistry, and Reflectance Spectra

A principal goal of the Lunar Soil Characterization Consortium (LSCC) is to evaluate tools that might be successfully used in remote compositional analysis of the lunar surface. Mathematical methods are extremely valuable to assess whether variations exist in a statistically significant manner, independent of their interpretation. The bounds of widely used correlation of visible to near-infrared spectral parameters with composition are first defined and evaluated. We then evaluate direct (or indirect) links between the combined spectral properties of lunar mare soils and their compositional properties (elemental abundance and mineralogy) through a statistical analysis of the variance across each measurement using principal component analysis (PCA). We first separately analyze LSCC elemental abundance, mineralogy, and spectroscopy data (0.35 to 2.5 μm) using PCA to capture the variance of each system with a relatively small number of independent variables. With this compact set of independent variables for each type of data, we derive functions to link composition and spectroscopy. For these mare soils, one of the best empirical predictive capability is that for FeO. This is not surprising since the effect of ferrous iron on optical properties is well documented. Although Al₂O₃ has no direct effect on optical properties, its strong anticorrelation with FeO also produces a relatively high predictive capability from spectra. Similarly, a high accuracy in predicting the abundance of pyroxene is observed and should be expected since iron-bearing pyroxene is one of the most optically active components of lunar soil. The accuracy for predicting either TiO₂ or ilmenite, on the other hand, is disappointing. High- and low-Ti soils are readily distinguished, but these statistics suggest that making subclass distinctions based on spectral predictions of TiO₂ would be risky.     

Analysis of the Distribution,Rotation and Scale Characteristics of Solar Wind Switchbacks:Comparison between the First and Second Encounters of Parker Solar Probe

The S-shaped magnetic structure in the solar wind formed by the twisting of magnetic field lines is called a switchback,whose main characteristics are the rever...     

Calculations of the energy levels and oscillator strengths of the Ne-like Fe Ion (Fe XVII)

Energy levels and oscillator strengths among the 27 fine-structure levels belonging to the (ls²2s²)2p⁶, 2p⁵3s, 2p⁵3p and 2p⁵3d configurations of the neon-like iron ion have been calculated using three atomic structure codes RCN/RCG, AUTOSTRUCTURE (AS) and GRASP. Relativistic corrections of the wave functions are taken into account in the RCN/RCG calculation. The results agree well with the available experimental and theoretical data. The accuracy of the three codes is analysed.     

Radiation Pressure and Surface Gravity of Close Binaries: First Results from Observational Data Analysis

We present the results from a sample of early type binaries, for which the surface gravity of their primary components was computed using two different ways. From a comparison of the derived gravity values, is found that the existing difference between them turns to vanish or even to inverse as the luminosity and temperature ratios increase. This implies the presence of radiation pressure, which strongly affects the calculations. A conclusion that has to be further investigated with a larger sample.     

The NOAA Goes-12 Solar X-Ray Imager (SXI) 1. Instrument, Operations, and Data

The Solar X-ray Imager (SXI) was launched 23 July 2001 on NOAAs GOES-12 satellite and completed post-launch testing 20 December 2001. Beginning 22 January 2003 it has provided nearly uninterrupted, full-disk, soft X-ray solar images, with a continuous frame rate significantly exceeding that for previous similar instruments. The SXI provides images with a 1 min cadence and a single-image (adjustable) dynamic range near 100. A set of metallic thin-film filters provides temperature discrimination in the 0.6 – 6.0 nm bandpass. The spatial resolution of approximately 10 arcsec FWHM is sampled with 5 arcsec pixels. Three instrument degradations have occurred since launch, two affecting entrance filters and one affecting the detector high-voltage system. This work presents the SXI instrument, its operations, and its data processing, including the impacts of the instrument degradations. A companion paper (Pizzo et al., this issue) presents SXI performance prior to an instrument degradation that occurred on 5 November 2003 and thus applies to more than 420000 soft X-ray images of the Sun.     

Beta decay of nuclides ~(56)Fe,~(62)Ni,~(64)Ni and ~(68)Ni in the crust of magnetars

By introducing the Dirac δ-function and Pauli exclusion principle in the presence of superstrong magnetic fields(SMFs), we investigate the influence of SMFs on beta decay and the change rates of electron fraction(CREF) of nuclides~(56)Fe,~(62)Ni,~(64)Ni and~(68)Ni in magnetars, which are powered by magnetic field energy. We find that the magnetic fields have a great influence on the beta decay rates, and the beta decay rates can decrease by more than six orders of magnitude in the presence of SMFs. The CREF also decreases by more than seven orders of magnitude in the presence of SMFs.     

Surficial Geologic Surveys of Gale Crater and Melas Chasma, Mars: Integration of Remote-Sensing Data

Remote-sensing observations of Gale Crater and Melas Chasma are synthesized to better understand the present surface layer in these two scientifically interesting regions. Data sets analyzed include geologic maps, Mars Orbiter Laser Altimeter (MOLA) elevation, Thermal Emission Spectrometer (TES) albedo, TES thermal inertia, MOLA residual pulse width, TES rock abundance, and Viking and Mars Orbiter Camera images. Using these data sets, we constrain the properties of and processes acting on the present surface and create self-consistent models for the surface layer. Surface properties within Gale Crater are variable and complex, and interpreting the surface layer is not straightforward. Observations indicate that aeolian processes have shaped some of the intracrater surface, but other areas do not comply with this model and have counterintuitive surface characteristics. In contrast, aeolian activity appears to have played a large role in shaping the present-day physical structure of all surfaces in Melas Chasma and is reflected in the remote-sensing data sets. Here we summarize our analysis and discuss the surface attributes as determined from these data sets.     

Observation of possible Fe xvii 2p 53p(1S0)-2p 53s(1 P 1, 3 P 1) transitions in spectra of a solar active region and flare

Expected wavelengths and relative intensities are obtained, from calculations of other workers, for the hitherto unobserved transitions 2p ⁵3p(¹ S ₀)-2p ⁵3s(¹ P ₁, ³ P ₁) in Fe xvii. A candidate pair of lines at 197.05 Å and 242.09 Å was found in laboratory spectra and appears to be present in the spectra of a solar active region observed by the OSO-7 Goddard spectroheliograph, and in the spectrum of a Skylab-observed solar flare.     

1.2米地平式望远镜指向模型的研究 (1.全天指向模型的建立)

介绍了云南天文台1.2米地平式望远镜用于天文观测和图像采集处理的方法,建立了新的、独特的全天指向模型,大大提高了该望远镜的指向精度,达到1″,并在多年的实际应用中得到验证。     

A New Analysis of Fireball Data from the Meteorite Observation and Recovery Project (MORP)

Sixty fireball cameras operated in Western Canada from 1971 to 1985. Over one thousand (1016) fireballs were recorded at more than one station, but only 367 were reduced, of which 285 have been published, including that of the Innisfree meteorite. Digitization of all the data is underway, and procedures are being developed which will allow the automatic reduction of events not previously examined. The results of the analysis of 80 fireballs reduced but not previously published are presented. When the new analysis is complete, the MORP archive will be a valuable source of information on meteoroid orbits.     

Spectral characteristics of iron-bearing phyllosilicates: Comparison to Orgueil (CI1), Murchison and Murray (CM2)

Abstract— Phyllosilicate alteration minerals are commonly found in low petrologic types of carbonaceous chondrites. Previous spectral studies have examined Mg-bearing phyllosilicates with limited success in matching the spectral properties of CM and CI chondrites. Transmission electron microscope and other analytical techniques suggest that Fe-bearing clays are more abundant in CI and CM chondrites than magnesian varieties. Here, we present the results of an examination of the reflectance spectra of Fe-phyllosilicates, including serpentines and berthierines, of which the latter were formerly known as septechlorites. We have measured the diffuse reflectance spectra of powdered samples from 0.3 to 25 μn. We find that these minerals provide a better spectral match to many of the features seen in CI and CM chondrites, and simple linear combinations of the spectra of both Fe- and Mg-phyllosilicates closely approximate the spectra of CM and CI chondrites.     

Neutrino energy spectrum and electron capture of Nuclides~(56))Fe,~(56)Co,~(56)Ni,~(56)Mn,~(56)Cr and~(56)V in stellar interiors

Based on the shell-model Monte Carlo method and random phase approximation theory,the neutrino energy spectrum(NES) and the electron capture(EC) of56 Fe,56Co,56 Ni,56Mn,56 Cr and56V are investigated in presupernova surroundings.The results show that the EC rates are affected greatly at different densities and temperatures. The rates increase greatly and even exceed six orders of magnitude at lower temperature. On the other hand,the NES is very sensitive to stellar temperature and electron energy. The higher the temperature and the lower the electron energy,the larger the influence on NES is. For example,the maxima of NES in the ground state are 9.02,160,80,24.01,0.44,1.42 me c2for56 Fe,56Co,56 Ni,56Mn,56 Cr and56V respectively at ρ7 = 10.7,Ye = 0.45 and T9 = 15. Furthermore,the influence on NES due to EC for different nuclei has some otherness because of different Q0-values. For example,the spectrum of56 Co shows a double bump structure.     

Analysis of Polarimetric,Photometric, and Spectroscopic Observations of Comet C/1996 Q1 (Tabur)

We present the imaging polarimetry and photometry of Comet C/1996 Q1 (Tabur) obtained on October 10, 1996, with a two-channel focal reducer attached to the 2-m Pik Terskol Observatory telescope through blue (4430/44 Å) and red (6420/26 Å) continuum filters and through a 6620/59 Å filter that isolated the NH₂(0.7.0) band. We analyze the 3600–9300 Å long-slit spectrograms of the comet taken on October 5–6, 1996, with the 2.6-m Crimean Astrophysical Observatory telescope. The NH₂(0.8.0) 6408 Å emission and an unidentified 6428 Å emission were found to fall within the pass band of the red filter. The blue filter transmits weak unidentified emissions at 4424–4444 Å and partially C₂(4360 Å). Correction for the depolarizing effect of molecular emissions resulted in an increase of the dust polarization by 2–4% in the near-nucleus region and by almost a factor of 2 in the outer coma regions. However, the polarization and color differences between different coma regions remained even after correction for the contribution of emissions. We found no dust polarization difference between the gas comet Tabur and the dust comet C/1988 A1 (Liller), which are believed to be fragments of a common parent comet. The NH₂coma was found to be elongated perpendicular to the comet radius vector. The causes of the spatial asymmetry in the NH₂molecular distribution are yet to be established. We study the evolution of activity and the spatial distribution of dust brightness, polarization, and color in the comet. We consider a taxonomic classification of gas and dust comets according to dust polarization properties. The polarization differences between dust and gas comets at large phase angles are most likely related both to the actual differences in dust and to the effect of molecular emissions, nuclear gas- and dust-production rates and to the evolution of grain properties with distance from the nucleus.