We investigated the magnitude-phase relation of (162173) 1999 JU3, a target asteroid for the JAXA Hayabusa 2 sample return mission. We initially employed the international Astronomical Union's H-G formalism but found that it fits less well using a single set of parameters. To improve the inadequate fit, we employed two photometric functions, the Shevchenko and Hapke functions. With the Shevchenko function, we found that the magnitude-phase relation exhibits linear behavior in a wide phase angle range (α = 5-75 • ) and shows weak nonlinear opposition brightening at α < 5 • , providing a more reliable absolute magnitude of H V = 19.25 ± 0.03. The phase slope (0.039 ± 0.001 mag deg −1 ) and opposition effect amplitude (parameterized by the ratio of intensity at α=0.3 • to that at α=5 • , I(0.3 • )/I(5 • )=1.31±0.05) are consistent with those of typical Ctype asteroids. We also attempted to determine the parameters for the Hapke model, which are applicable for constructing the surface reflectance map with the Hayabusa 2 onboard cameras. Although we could not constrain the full set of Hapke parameters, we obtained possible values, w=0.041, g=-0.38, B 0 =1.43, and h=0.050, assuming a surface roughness parameterθ=20 • . By combining our photometric study with a thermal model of the asteroid (Müller et al. in preparation), we obtained a geometric albedo of p v = 0.047 ± 0.003, phase integral q = 0.32 ± 0.03, and Bond albedo A B = 0.014 ± 0.002, which are commensurate with the values for common C-type asteroids.

The Hyogo-ken Nanbu earthquake (JMA Magnitude=7.2) occurred on January 17, 1995, near Kobe in Hyogo-ken prefecture, Japan. Unusual pulsed radio emissions at 22.2 MHz (wavelength-13.5 m) were detected with a radio interferometer at Nishi-harima Astronomical Observatory, located about 77 km from the epicenter, both before and after this earthquake. These data indicate that one of the most probable source regions was the central part of the Nojima fault, about 25 km from downtown Kobe, and the average pulsed power appeared to be about 0.2 W. Res., 87, 2851-2859, 1982. Yamada, I., K. Masuda, and H. Mizutani, Electromagnetic and acoustic emission associated with rock fracture, Phys. Earth Planet. Inter., 57, 157-168, 1989. Yoshida, S., P. Manjgaladze, D. Zilpimiani, M. Ohnaka, and M. Nakatani, Electromagnetic emissions associated with frictional sliding of rock, in Electromagnetic Phenomena

Multi-wavelength observations of the black-widow binary system 2FGL J2339.6−0532 are reported. The Fermi gamma-ray source 2FGL J2339.6-0532 was recently categorized as a black widow in which a recycled millisecond pulsar (MSP) is evaporating up the companion star with its powerful pulsar wind. Our optical observations show clear sinusoidal light curves due to the asymmetric temperature distribution of the companion star. Assuming a simple geometry, we constrained the range of the inclination angle of the binary system to 52 • < i < 59 • , which enables us to discuss the interaction between the pulsar wind and the companion in detail. The X-ray spectrum consists of two components: a soft, steady component that seems to originate from the surface of the MSP, and a hard variable component from the wind-termination shock near the companion star. The measured X-ray luminosity is comparable to the bolometric luminosity of the companion, meaning that the heating efficiency is less than 0.5. In the companion orbit, 10 11 cm from the pulsar, the pulsar wind is already in particle dominant-stage, with a magnetization parameter of σ < 0.1. In addition, we precisely investigated the time variations of the X-ray periodograms and detected a weakening of orbital modulation. The observed phenomenon may be related to an unstable pulsar-wind activity or a weak mass accretion, both of which can result in the temporal extinction of radio-pulse.

We present the results of photometric observations carried out with four small telescopes of the asteroid 4 Vesta in the B, R C , and z ′ bands at a minimum phase angle of 0.1 • . The magnitudes, reduced to unit distance and zero phase angle, were M B (1,1,0) = 3.83 ± 0.01,M R C (1,1,0) = 2.67 ± 0.01, and M z ′ (1,1,0) = 3.03 ± 0.01 mag. The absolute magnitude obtained from the IAU H-G function is ∼0.1 mag darker than the magnitude at a phase angle of 0 • determined from the Shevchenko function and Hapke models with the coherent backscattering effect term. Our photometric measurements allowed us to derive geometric albedos of 0.35 in the B band, 0.41 in the R C band, and 0.31 in the z ′ bands by using the Hapke model with the coherent backscattering effect term. Using the Hapke model, the porosity of the optically active regolith on Vesta was estimated to be ρ = 0.4-0.7, yielding the bluk density of 0.9-2.0 × 10 3 kg m −3 . It is evident that the opposition effect for Vesta makes a contribution to not only the shadow-hiding effect, but also the coherent backscattering effect that 1 appears from ca. 1 • . The amplitude of the coherent backscatter opposition effect for Vesta increases with a brightening of reflectance. By comparison with other solar system bodies, we suggest that multiple-scattering on an optically active scale may contribute to the amplitude of the coherent backscatter opposition effect (B C0 ).

[1] We present evidence for ionospheric effects caused by the gamma ray burst that originated at a cosmological distance. At the time of the strong cosmic gamma-ray burst of 29 March 2003 (GRB030329) that took place in the nighttime in Japan we observed a transient decrease in the strength of the radio noise coming from extraterrestrial sources (cosmic noise) at 38 MHz. We also observed a sudden field-amplitude decrease of an 8.006 MHz transmission signal recorded at a distance of 690 km from the transmitter. These phenomena are interpreted as a result of an ionospheric absorption enhancement due to transient ionization caused by GRB030329. We also report no appreciable effect on the ionospheric electron column content derived using GPS (Global Positioning System) microwave signals.