Effects of gravistimuli on osmoregulation in azuki bean epicotyls

The effects of hypergravity on growth and osmoregulation were examined in dark-grown azuki bean epicotyls. Elongation growth of epicotyls was promptly suppressed by hypergravity at 300g. On the contrary, the increase in fresh weight of epicotyls during incubation was not suppressed by hypergravity at 300g at least up to 6 h. Also, the level of total osmotic solutes increased during epicotyl growth for 6 h, which was not affected by hypergravity. These results suggest that azuki bean epicotyls are capable of maintaining osmoregulation even under 300g conditions for a short period. On the other hand, the increase in fresh weight of epicotyls was suppressed, in addition to suppression of elongation growth, when seedlings were treated with 300g for 24 h. The increase in level of total osmotic solutes was also inhibited by 24 h hypergravity treatment, which was accounted by the reduced levels of organic solutes, such as sugars and amino acids. Furthermore, the dry weight of seeds decreased during incubation for 24 h, but the decrease was inhibited by hypergravity at 300g. Hypergravity treatment at 300g for 24 h also increased the pH value of apoplastic solution in epicotyls. Taken together, these results suggest that the translocation of organic solutes from the seed to epicotyls is inhibited by prolonged hypergravity treatment, which may underlie the suppression of epicotyl growth, and that the breakdown of H⁺ gradient across the plasma membrane in epicotyl cells may be at least partly involved in the reduction of organic solute accumulation under hypergravity conditions.     

Growth restoration in azuki bean and maize seedlings by removal of hypergravity stimuli.

Hypergravity stimuli, gravitational acceleration of more than 1 x g, decrease the growth rate of azuki bean epicotyls and maize coleoptiles and mesocotyls by decreasing the cell wall extensibility via an increase in the molecular mass of matrix polysaccharides. An increase in the pH in the apoplastic fluid is hypothesized to be involved in the processes of the increase in the molecular mass of matrix polysaccharides due to hypergravity. However, whether such physiological changes by hypergravity are induced by normal physiological responses or caused by physiological damages have not been elucidated. In the present study, we examined the effects of the removal of hypergravity stimuli on growth and the cell wall properties of azuki bean and maize seedlings to clarify whether the effects of hypergravity stimuli on growth and the cell wall properties are reversible or irreversible. When the seedlings grown under hypergravity conditions at 300 x g for several hours were transferred to 1 x g conditions, the growth rate of azuki bean epicotyls and maize coleoptiles and mesocotyls greatly increased within a few hours. The recovery of growth rate of these organs was accompanied by an immediate increase in the cell wall extensibility, a decrease in the molecular mass of matrix polysaccharides, and an increase in matrix polysaccharide-degrading activities. The apoplastic pH also decreased promptly upon the removal of hypergravity stimuli. These results suggest that plants regulate the growth rate of shoots reversibly in response to hypergravity stimuli by changing the cell wall properties, by which they adapt themselves to different gravity conditions. This study also revealed that changes in growth and the cell wall properties under hypergravity conditions could be recognized as normal physiological responses of plants. In addition, the results suggest that the effects of microgravity on plant growth and cell wall properties should be reversible and could disappear promptly when plants are transferred from microgravity to 1 x g. Therefore, plant materials should be fixed or frozen on orbit for detecting microgravity-induced changes in physiological parameters after recovering the materials to earth in space experiments.     

Features of the 11-year variation of galactic cosmic rays in different periods of solar magnetic cycles

Variations of galactic cosmic ray intensity have been studied based on the neutron monitors and interplanetary magnetic field experimental data for different ascending and descending epochs of solar activity. The dependence of the diffusion coefficient on the cosmic ray particles rigidity R is stronger in the maxima epoch than in the minima epoch of solar activity. For the period of 1977–1981 (qA > 0) the diffusion coefficient for the minimum epoch is, χ_min ∝ R^{0.7 ± 0.04} and for the maximum χ_max ∝ R^{1.3 ± 0.05}; for the period of 1987–1990 (qA < 0), χ_min ∝ R^{0.8 ± 0.05} and χ_max ∝ R^{1.1 ± 0.04}. The exponents ν_y and ν_z of the power spectral density of the B_y and B_z components of the IMF in the region of the frequencies (10⁻⁶– 4 × 10⁻⁶) Hz are larger for the minimum epoch of 1987 (ν_y ≈ 2.0 and ν_z ≈ 1.93) than for the maximum epoch of 1990 (ν_y ≈ 1.43 and ν_z ≈ 1.27).     

Scaling and universality of the thermal conductivity of liquid 4He near the superfluid transition and in restricted geometries

We present measurements of the thermal conductivity λ(t, P, L) = l/ρ(t, P, L) near the superfluid transition of ⁴He at saturated vapor pressure and confined in cylindrical geometries with radii L = 0.5 and 1.0 μm (t ≡ T/T_λ(P) − 1). For L = 1.0 μm measurements at six pressures P are presented. At and above T_λ the data are consistent with a universal scaling function F(X) = (L/ξ_o)^x/ν(ρ/ρ₀), X = (L/ξ_o)^1/νt valid for all P (ρ₀ and x are the pressure-dependent amplitude and effective exponent of the bulk resistivity ρ(t, P, ∞) = ρ₀t^x and ξ = ξ₀t^−ν is the correlation length). Indications of breakdown of scaling and universality are observed below T_λ.     

Hard X-ray footpoint motions in solar flares: Comparing magnetic reconnection models with observations

Hard X-ray observations from the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) of the October 29, 2003 GOES X10 two-ribbon flare are used together with magnetic field observations from the Michelson Doppler Imager (MDI) onboard SoHO to compare footpoint motions with predictions from magnetic reconnection models. The temporal variations of the velocity v of the hard X-ray footpoint motions and the photospheric magnetic field strength B in footpoints are investigated. The underlying photospheric magnetic field strength is generally higher (B ∼ 700–1200 G) in the slower moving (v ∼ 20–50 km s⁻¹) western footpoint than in the faster (v ∼ 20–100 km s⁻¹) moving eastern source (∼100–600 G). Furthermore, a rough temporal correlation between the HXR flux and the product vB² is observed.     

Hypergravity-induced changes in gene expression in Arabidopsis hypocotyls.

Under hypergravity conditions, the cell wall of stem organs becomes mechanically rigid and elongation growth is suppressed, which can be recognized as the mechanism for plants to resist gravitational force. The changes in gene expression by hypergravity treatment were analyzed in Arabidopsis hypocotyls by the differential display method, for identifying genes involved in hypergravity-induced growth suppression. Sixty-two cDNA clones were expressed differentially between the control and 300 g conditions: the expression levels of 39 clones increased, whereas those of 23 clones decreased under hypergravity conditions. Sequence analysis and database searching revealed that 12 clones, 9 up-regulated and 3 down-regulated, have homology to known proteins. The expression of these genes was further analyzed using RT-PCR. Finally, six genes were confirmed to be up-regulated by hypergravity. One of such genes encoded 3-hydroxy-3-methylglutaryl-Coenzyme A reductase (HMGR), which catalyzes a reaction producing mevalonic acid, a key precursor of terpenoids such as membrane sterols and several types of hormones. The expression of HMGR gene increased within several hours after hypergravity treatment. Also, compactin, an inhibitor of HMGR, prevented hypergravity-induced growth suppression, suggesting that HMGR is involved in suppression of Arabidopsis hypocotyl growth by hypergravity. In addition, hypergravity increased the expression levels of genes encoding CCR1 and ERD15, which were shown to take part in the signaling pathway of environmental stimuli such as temperature and water, and those of the alpha-tubulin gene. These genes may be involved in a series of cellular events leading to growth suppression of stem organs under hypergravity conditions.     

The spatial distribution of galactic and anomalous cosmic rays in the heliosphere at solar minimum

The spatial distributions of galactic and anomalous cosmic rays in the heliosphere at the solar minima of Cycles 20/22 (qA > 0) and of Cycle 21 (qA < 0) are studied, using data from IMP 8, Voyagers 1/2 and Pioneer 10. It is found that the radial dependences of intensities J can be approximated by a power of radial distance r as J ∝ r^α with a different value of a constant in the inner and outer heliosphere with a transition at a radial distance of 10–15 AU. To study the physical meaning of these radial intensity profiles we examined the rigidity dependences of the intensity gradients by determining the particle mean free paths, using a simple one-dimensional modulation model. The particle mean free path λ was assumed to be a separable function of distance of the form r^γ and rigidity R of R^δ over the range of 0.5–3.0 GV in the inner and outer heliosphere. It was shown that λ of rigidity dependence of R^1.6 determined for Cycle 20/22 (qA > 0) with anomalous He is about 4–5 times larger than that of Cycle 21 (qA < 0) with R^0.9 at around 1 GV in the outer heliosphere, and that the radial dependences are r^1.4 and r^1.1, respectively, for Cycles 20/22 and for Cycle 21.     

Excitations of nonmigrating diurnal tides in the mesosphere and lower thermosphere simulated by the Kyushu-GCM

Excitation mechanisms of nonmigrating diurnal tides in the MLT region simulated by the Kyushu-GCM are examined. It is shown that the westward propagating diurnal tide with zonal wavenumber s = 2 is mainly excited by nonlinear interactions between the migrating diurnal tide and the stationary planetary wave with zonal wavenumber s = 1, while the nonlinear excitation of the standing diurnal tide with zonal wavenumber s = 0 is less important than the excitation by tropospheric heating. Nonlinear interactions between the migrating diurnal tide and the stationary planetary wave with zonal wavenumber s = 2 are not dominant to excite the westward propagating diurnal tide with zonal wavenumber s = 3, and it is shown that the excitation by tropospheric heating is comparable to the nonlinear excitation. It is also shown that other nonmigrating diurnal tides are excited by tropospheric heating.     

Gamma-ray observations of explosive nucleosynthesis products

In this review I discuss the various γ-ray emission lines that can be expected and, in some cases have been observed, from radioactive explosive nucleosynthesis products. The most important γ-ray lines result from the decay chains of ⁵⁶Ni, ⁵⁷Ni, and ⁴⁴Ti. ⁵⁶Ni is the prime explosive nucleosynthesis product of Type Ia supernovae, and its decay determines to a large extent the Type Ia light curves. ⁵⁶Ni is also a product of core-collapse supernovae, and in fact, γ-ray line emission from its daughter product, ⁵⁶Co, has been detected from SN1987A by several instruments. The early occurrence of this emission was surprising and indicates that some fraction of ⁵⁶Ni, which is synthesized in the innermost supernova layers, must have mixed with the outermost supernova ejecta.Special attention is given to the γ-ray line emission of the decay chain of ⁴⁴Ti (⁴⁴Ti → ⁴⁴Sc → ⁴⁴Ca), which is accompanied by line emission at 68, 78, and 1157 keV. As the decay time of ⁴⁴Ti is ∼86 yr, one expects this line emission from young supernova remnants. Although the ⁴⁴Ti yield (typically 10⁻⁵–10⁻⁴M_⊙) is not very high, its production is very sensitive to the energetics and asymmetries of the supernova explosion, and to the mass cut, which defines the mass of the stellar remnant. This makes ⁴⁴Ti an ideal tool to study the inner layers of the supernova explosion. This is of particular interest in light of observational evidence for asymmetric supernova explosions.The γ-ray line emission from ⁴⁴Ti has so far only been detected from the supernova remnant Cas A. I discuss these detections, which were made by COMPTEL (the 1157 keV line) and BeppoSAX (the 68 and 78 keV lines), which, combined, give a flux of (2.6 ± 0.4 ± 0.5) × 10⁻⁵ ph cm⁻² s⁻¹ per line, suggesting a ⁴⁴Ti yield of (1.5 ± 1.0) × 10⁻⁴M_⊙. Moreover, I present some preliminary results of Cas A observations by INTEGRAL, which so far has yielded a 3σ detection of the 68 keV line with the ISGRI instrument with a flux that is consistent with the BeppoSAX detections. Future observations by INTEGRAL-ISGRI will be able to constrain the continuum flux above 90 keV, as the uncertainty about the continuum shape, is the main source of systematic error for the 68 and 78 keV line flux measurements. Moreover, with the INTEGRAL-SPI instrument it will be possible to measure or constrain the line broadening of the 1157 keV line. A preliminary analysis of the available data indicates that narrow line emission (i.e., Δv < 1000 km s⁻¹) can be almost excluded at the 2σ level, for an assumed line flux of 1.9 × 10⁻⁵ ph cm⁻² s⁻¹.     

On the quality of mutations in mammalian cells induced by high LET radiations

The deleterious effects of accelerated heavy ions as component of the space radiation environment on living cells are of increasing importance for long duration human space flight activities. The most important aspect of such densely ionizing particle radiation is attributed to the type and quality of biological damage induced by them. This issue is addressed by investigating cell inactivation and mutation induction at the Hprt locus (coding for hypoxanthine-guanine-phosphoribosyl-transferase) of cultured V79 Chinese hamster cells exposed to densely ionizing radiation (accelerated heavy ions with different LETs from oxygen to gold, specific energies ranging from 1.9 to 69.7 MeV/u, corresponding LET values range from 62 to 13,223 keV/μm) and to sparsely ionizing radiation (200 kV X-rays). 30 spontaneous, 40 X-ray induced and 196 heavy ion induced 6-thioguanine resistant Hprt mutant colonies were characterized by Southern technique using the restriction enzymes EcoRI, PstI and BglII and a full length Hprt cDNA probe isolated from the plasmid pHPT12. Restriction patterns of the spontaneous Hprt mutants were indistinguishable from the wild type pattern, as these mutants probably contain only small deletions or even point mutations in the Hprt locus. In contrast, the overall spectrum of heavy ion induced mutations revealed a majority of partial or total deletions of the Hprt gene. With constant particle fluence (3 × 10⁶ particles/cm²) the quality of heavy ion induced mutations in the Hprt locus depends on physical parameters of the beam (atomic number, specific energy, LET). This finding suggests a relationship between the type of DNA damage and track structure. The fraction of mutants with severe deletions in the Hprt locus after exposure to oxygen ions increases from 65% at 60 keV/μm up to a maximum (100%) at 300 keV/μm and declines with higher LET values to 75% at 750 keV/μm. With heavier ions (Ca- and Au-ions) and even higher LET-values this mutant fraction decreases to 58% at 13,200 keV/μm. Heavy ion induced DNA break points in the Hprt locus are not randomly distributed.     

XMM-Newton observations of the Mouse,SLX 1744–299 and SLX 1744–300

We observed the radio and X-ray source G359.23–0.82, also known as “the Mouse”, with XMM-Newton. The X-ray image of this object shows a point-like source at the Mouse’s “head”, accompanied by a “tail” that extends for about 40″ westward. The morphology is consistent with that observed recently with Chandra [Gaensler, B.M., van der Swaluw, E., Camilo, F., et al. The Mouse that soared: high resolution X-ray imaging of the pulsar-powered bow shock G359.23–0.82, ApJ 616, 383–402, 2004]. The spectrum of the head can be described by a power-law model with a photon index Γ ≃ 1.9. These results confirm that the Mouse is a bow-shock pulsar wind nebula (PWN) powered by PSR J1747–2958. We found that the hydrogen column density toward the Mouse, N_H = (2.60 ± 0.09) × 10²² cm⁻², is 20%–40% lower than those toward two serendipitously detected X-ray bursters, SLX 1744–299 and SLX 1744–300. At a plausible distance of 5 kpc, the X-ray luminosity of the Mouse, L(0.5–10 keV) = 3.7 × 10³⁴ erg s⁻¹, is 1.5% of the pulsar’s spin-down luminosity. We detected a Type I X-ray burst from SLX 1744–300 and found a possible decrease of N_H and persistent luminosity for this source, in comparison with those observed with ROSAT in 1992.     

The role of drift and convection–diffusion mechanisms in small energy global cosmic ray modulation: Application to the hysteresis phenomenon of proton and alpha particle satellite data

The hysteresis effect for small energies of galactic cosmic rays is due to two effects. The first is the same as for neutron monitor energies – the delay of the interplanetary processes responsible for cosmic ray modulation with respect to the initiating solar processes, according to the effective velocity of solar wind and shock waves propagation. Then, the observed cosmic ray intensity is connected to the solar activity variations during many months before the time of cosmic ray measurement. The second is caused by the time delay of small energy cosmic ray diffusion from the boundary of modulation region to the Earth’s orbit. The model describing the connection between solar activity variation and cosmic ray convection–diffusion global modulation for neutron monitor energies is here developed by taking into account also the time-lag of the small energy particle diffusion in the Heliosphere. We use theoretical results on drifts and analytically approximate the dependences of drifts from tilt angle, and take into account the dependence from the sign of primary particles, and from the sign of polar magnetic field (A > 0 or A < 0). The obtained results are applied on proton and alpha-particle satellite data. We analyze satellite 5-min data of proton fluxes with energies >1 MeV, >2 MeV, >5 MeV, >10 MeV, >30 MeV, >50 MeV, >60 MeV, >100 MeV, and in intervals 10–30 MeV, 30–60 MeV, and 60–100 MeV during January 1986–December 1999. We exclude periods with great cosmic ray increases caused by particle acceleration in solar flare events. Then, we determine monthly averaged fluxes, as well as 5-month and 11-month smoothed data. We analyze also satellite 5-min data on alpha-particle fluxes in the energy intervals 60-160 MeV, 160–260 MeV and 330–500 MeV during January 1986–May 2000. We correct observation data for drifts and then compare with what is expected according to the convection–diffusion mechanism. We assume different dimensions of the modulation region (by the time propagation X₀ of solar wind from the Sun to the boundary of modulation region), for X₀ values from 1 to 60 average months, by one-month steps. For each value of X₀ we determine the correlation coefficient between variations of expected and observed cosmic ray intensities (the estimation of cosmic ray intensities values is given in Section 3 by Eq. (9), and the determination of correlation and regression coefficients in Section 3 by Eq. (8)). The dimension of modulation region is determined by the value of X_0 max, for which the correlation coefficient reaches the maximum value. Then the effective radial diffusion coefficient and residual modulation in small energy region can be estimated.     

Supernova remnant 1987A: The latest report from the Chandra X-ray Observatory

We continue monitoring supernova remnant (SNR) 1987A with the Chandra X-ray Observatory. As of 2004 January, bright X-ray spots in the northwest and the southwest are now evident in addition to the bright eastern ring. The overall X-ray spectrum, since 2002 December, can be described by a planar shock with an electron temperature of ∼2.1 keV. The soft X-ray flux is now 8 × 10⁻¹³ ergs cm⁻² s⁻¹, which is about five times higher than four years ago. This flux increase rate is consistent with our prediction based on an exponential density distribution along the radius of the SNR between the HII region and the inner ring. We still have no direct evidence of a central point source, and place an upper limit of L_X = 1.3 × 10³⁴ ergs s⁻¹ on the 3–10 keV band X-ray luminosity.     

Centre-to-limb variation of photospheric facular radiance and image resolution

We study the effect of the angular resolution on the determination of the angular properties of the facular radiance. We analyze photospheric intensity in the continuum, around the Ni 676.8 nm line, and longitudinal magnetic field along the line of sight, measured by the MDI instrument aboard SOHO with two spatial resolutions, 4″ and 1.2″ (2″ and 0.6″ pixels, respectively). The effect of the limited photometric sensitivity of the instrument and the limited information on the angular structure of the magnetic field tubes are considered. Our study of the high-resolution data shows that intensity contrast of magnetic features between 80 and 600 Gauss increases from centre to limb up to a maximum that occurs at higher heliocentric angles (θ) when obtained with higher resolution data than for lower resolution data. There is a suggestion that at heliocentric angles below about 75° there is only a monotonic increase in the contrast as one goes from cos (θ) = 1 to cos (θ) = 0.2.     

A Gemini observation of the anomalous X-ray pulsar 1RXS J170849-400910

The anomalous X-ray pulsars (AXPs) represent a growing class of neutron stars discovered at X-ray energies. While the nature of their multi-wavelength emission mechanism is still under debate, evidence has been recently accumulating in favor of their magnetar nature. Their study in the optical and infrared (IR) wavelengths has recently opened a new window to constrain the proposed models. We here present a brief overview of AXPs and our Gemini-South observation of 1RXS J170849-400910, which is a relatively bright AXP discovered with ROSAT and later found to be an 11 s X-ray pulsar by ASCA. The observation was taken with the near-IR imager Flamingos in J (1.25 μm), H (1.65 μm), and K_s (2.15 μm). We confirm the recent detection by (ApJ, 589, L93–L96) of a source coincident with the CHANDRA source (candidate ‘A’). Our derived magnitudes of J = 20.6 (0.2), H = 18.6 (0.2), and K_s = 17.1 (0.2) are consistent with those derived by (ApJ, 589, L93–L96), and indicate that if this source is indeed the IR counterpart to 1RXS J170849-400910, then there is no evidence of variability from this AXP. However, given the lack of IR variability and the relatively high IR to X-ray flux of this source when compared to the other AXPs, we conclude that this source is unlikely the counterpart of the AXP, and that the other source (candidate ‘B’) within the CHANDRA error circle should not be ruled out as the counterpart. Further monitoring of these sources and a deep observation of this complex field are needed to confirm the nature of these sources and their association with the AXP.     

Modeling the effects of pitch-angle scattering processes on the transport of solar energetic particles along the interplanetary magnetic field

We present a Monte-Carlo technique to study the time-dependent transport of energetic particles in the interplanetary medium. We use the guiding center approximation between discrete finite pitch-angle scatterings to quantify the competing effects of focusing and pitch-angle scattering on energetic particles propagating along a Parker spiral magnetic field. We consider that the pitch-angle scattering process is produced by small-scale magnetic field irregularities frozen in the expanding solar wind. We also include the effects of both solar wind convection and adiabatic deceleration. We use a joint probability distribution P(h, μ′) = p(h; μ′)q(μ′; μ) to describe both the distance traveled by the particle between two scattering processes and the change in the particle pitch-angle after a scattering process. Here, p(h; μ′) is the conditional probability that the particle travels a distance h along the field line before the next scattering if it had a pitch-angle cosine μ′ after the previous scattering, and q(μ′; μ) is the conditional probability for the pitch-angle cosine μ′ if the pitch-angle cosine was μ before the scattering. We consider several functional forms to describe the processes of pitch-angle scattering, such as an isotropic scattering without any memory of the initial particle’s pitch-angle or processes in which the scattering result depends upon the initial particle’s pitch-angle. The results of our simulations are pitch-angle distributions and time-intensity profiles that can be directly compared to spacecraft observations. Comparison of our simulations with near-relativistic (45–290 keV) electron events observed by the Electron, Proton and Alpha Monitor on board the Advanced Composition Explorer allows us to estimate both the time dependence of the injection of near-relativistic electrons into the interplanetary medium and the conditions for electron propagation along the interplanetary magnetic field.     

On long-term changes of electron density in the upper mesosphere

Recent review study done jointly by 19 experts of 17 institutes shows zero trend of temperature in the upper mesosphere. In the light of this latest development, we have examined the long-term changes in electron density, [e], in this region. The study has been concentrated at 80 km. At this altitude, electrons are mainly produced by the interaction of nitric oxide, NO, by solar Ly-α. Any long-term change in this flux will affect trend of [e]. Considering this flux proportional to 10.7 cm solar flux, analysis of available 10.7 cm solar flux data from 1948 to 2003 has been made. A decreasing trend up to about 1970 and then an increasing trend are found. The over-all increasing trend of Ly-α flux during the past five decades is ∼0.17% per year. This increase also gives a ∼0.17% increasing trend per year in [e]. This non-anthropogenic increase is much less compared to the observed increase in [e] which is reported to be >0.7% per year. The observed increase in [e] of this magnitude will then, predominantly, be due to the anthropogenic effect. In zero trend in temperature, significant change in electron loss coefficient, α_eff, and [NO] are unlikely to take place to cause a significant change in [e]. The increase in [e] > 0.7% per year then can be explained by considering a decreasing trend in [O₂].     

Spectral filter for signal identification in the kHz SLR measurements of the fast spinning satellite Ajisai

The high repetition rate satellite laser ranging (SLR) measurements to the fast spinning satellites contain a frequency signal caused by the rotational motion of the corner cube reflector (CCR) array. The spectral filter, developed here, is based on the Lomb algorithm, and is tested with the simulated and the observed high repetition rate SLR data of the geodetic satellite Ajisai (spin period ∼2 s). The filter allows for the noise elimination from the SLR data, and for identification of the returns from the single CCRs of the array – even for the low return rates. Applying the spectral filter to the simulated SLR data increases the S/N ratio by a factor 40–45% for all return rates. Filtering out the noise from the observed data strengthens the frequency signal by factor of ∼25 for the low return rates, which significantly helps to determine the spin phase of the satellite. The spectral filter is applied to the Graz SLR data and the spin rates of Ajisai are determined by two different methods: the frequency analysis and the phase determination of the spinning retroreflector array.The analysis of more than 8 years of the Graz SLR measurements indicates an exponential spin rate trend: f = 0.67034 exp(−0.0148542 Y) [Hz], RMS = 0.085 mHz, where Y is the year since launch. The highly accurate spin rate information demonstrates periodic changes related to the precession of the orbital plane of Ajisai, as it determines the amount of energy received by the satellite from the Sun. The rate of deceleration of Ajisai is not constant: the half life period of the satellite’s spin oscillates around 46.7 years with an amplitude of about 5 years.     

Multi-wavelength study of a strong impulsive solar limb flare on 2002 August 3

We made a detailed study of the impulsive solar flare of GOES class X1.0 which occurred near the west limb on 2002 August 3, peak time 19:07 UT. There is particularly good data coverage of this event, with simultaneous observations in EUV, soft and hard X-rays available. We used TRACE 171 Å images to study the morphology and evolution of this event. Soft X-ray spectra in the wavelength range 3.34–6.05 Å measured by the RESIK Bragg crystal spectrometer on CORONAS-F were used for determination of the evolution of the flare plasma temperature. Data from the RHESSI instrument were used to investigate properties of the higher-temperature plasma during the flare.