[en] To date, several rocket observations of cosmic soft X-ray have been performed, and the celestial sphere distribution of soft X-ray intensity has been measured. It was found that the celestial sphere distribution of soft X-ray was not simple, and did not correlate with the distribution of neutral hydrogen density. In the observation of soft X-ray, however, the electrons precipitated from the manetosphere and ultra-violet radiation disturb the detection of cosmic soft X-ray. In the present observation, the two-tier proportional counter system was used to discriminate electrons from X-ray. The K-9M-52 rocket was launched on Sept. 20, 1975, and the 0.08-1.0 keV X-ray range was measured. The soft X-ray from the north galactic pole, the south galactic pole, North Polar Spur, HI hole and Lupus Loop were detected. (Yoshimori, M.)

[en] The fourth rocket observation of cosmic soft X-ray was performed by the X-ray astronomy groups of Leiden University and Nagoya University on May 28, 1976. The purposes of the observation were to measure the spatial structure and the energy spectra of North Polar Spur and Lupus Loop, and to detect the soft X-ray from HZ 43 and α Vir. The detection system consists of the large-area proportional counter for the measurement of soft X-ray spectra and the multiwire proportional counter for the measurement of the spatial structure of X-ray sources. The former counter covered the 0.1-3 keV energy range, and the latter the 0.05-1.0 keV energy range. The observed result showed the counting rate peaks from North Polar Spur, Lupus Loop and HZ 43. The data analysis is now in progress, and the preliminary data is reported. (Yoshimori, M.)

[en] The purposes of the observation are to calibrate the instrument with X-ray from Crab Nebula, to search for X ray from MONOCEROS supernova, to investigate the structure and the energy spectrum in the strong X-ray regions in Gemini and Eridanus, and to search for X ray from Orion region. The soft X ray detectors employed in the present observation were eight membrane proportional counters and a multi-wire proportional counter. To improve the energy resolution, 1 μm, 1.5 μm and 3 μm thick polypropylene filters and 120 μg/cm² thick boron filter were used. The effective area of one proportional counter was 134 cm² and soft X-ray between 0.4 and 2 keV was detected. The sandhawk rocket was launched on Nov. 9, 1974, and the aspect control was made. The expected observation was made. (J.P.N.)

[en] The polypropylene membrane of 1μm thick was developed, and it is widely used as the window material for the proportional counters for the detection of soft X-ray. Several observations of cosmic soft X-ray have been performed, and the energy spectra of diffuse soft X-ray and the spatial distribution have been measured. The observed results showed that the intensity of soft X-ray was much higher than that extrapolated from the energy spectra of the diffuse component measured above 1 keV. The proportional counter system of 660 cm² area and the 2.8 deg x 11 deg (FWHN) field of view was used for the detection of 0.1-1.5 keV soft X-ray. The K-9M-44 rocket was launched on Aug. 27, 1973, and the energy spectra of diffuse soft X-ray were measured. The result showed that the energy spectra outside. Radio Loop I was different from that inside it, the soft X-ray intensities from the galactic north pole and the HI hole region were higher than those from other regions, and the energy spectra were enhanced near 0.5-0.8 keV in North Polar Spur and Lupus Loop regions. The X-ray emission model was suggested for the explanation of the energy spectra outside Radio Loop I. (Yoshimori, M.)

[en] In 1974-1975, the occultation of Crab Nebula by the moon occurred, which was observed in various parts of the world to study the X-ray source structure of the nebula. The X-ray from Crab Nebula is generally considered to be synchrotron radiation due to the high-energy electrons similarly to the radio waves and the light. In order to examine the structure in hard X-ray region particularly, the observation was made with two balloons on January 24, 1975. The dimension in the hard X-ray region (average 50 KeV is from 1/2 to 1/3 of 100sec in the several kev region. The center position of the hard X-ray source does not coincide with the pulsar. (Mori, K.)

[en] It has been presumed on the basis of the observations of soft X-ray using thin membrane window proportional counters that the homogeneous component of soft X-ray and the soft X-ray from supernova remnants are produced by the hot plasma of 10⁵-10⁷ deg K. Intensive line emissions of oxygen, iron and silicon are also observed in 10-100 A wave length range. The line emissions from North Polar Spur and Lupus Loop were detected by the K-9M-44 rocket observation, and the seemed to be the contribution by oxygen. It is difficult to determine the accurate line contribution because of the low energy resolution of proportional counters. To measure line emissions with high resolution detectors and to study the gas temperature and composition of interstellar hot plasma and supernova remnants, the Bragg crystal spectrometer with the proportional scintillation counter or the organic crystal is proposed. The proportional scintillation counter is superior in the detection efficiency and the organic crystal is superior in the wave length resolution. In the present study, the Bragg crystal spectrometer consisting of potassium acid phthalate and the position sensitive counter with thin membrane window (1 μm polypropylene) was designed, and the energy resolution was estimated. (Yoshimori, M.)

[en] Galactic soft X-ray was observed with the K-9M-50 rocket with the thin membrane window proportional counter. The detection system consists of six proportional counters filled with PR gas, and the total ray-receiving area is 600 cm². The spatial distribution and the energy spectra were measured in the following X-ray energy ranges, 0.8-1.6 keV, 0.4-0.8 keV, 0.2-0.4 keV and 0.7-0.2 keV. The strong X-ray sources of Tau X-1, Cyg X-1, X-2, X-3 and LMC were detected in the 0.8-1.6 keV range. The Vela, Pup and Cyg regions were observed in the 0.4-0.8 keV range. The Vela and Cyg-Loop were detected in the 0.2-0.4 keV and 0.1-0.2 keV ranges. The energy spectra from the plane region, the enhanced region and the HI hole region were measured. The hot plasma model of about 10⁶ deg K was proposed as the diffuse soft X-ray source. (Yoshimori, M.)

[en] As a means to study the structure of Galaxy, the diffuse component of infrared ray has been observed with a balloon. Such observation is significant because the observation up to the galactic center is possible, it is advantageous for knowing the global structure of whole Galaxy, and the distribution of other stars than those in the visible region can be revealed. The observations of the galactic longitude from 23 deg to 70 deg and the center were made in September 1975 and May 1976, respectively. The interpretation of the former observation results previously reported and the report of the latter observation results are given. (Mori, K.)

[en] The sky mapping of especially the isotropic component of soft X-ray of galactic origin has been made to investigate the origin of soft X-ray. It is well known that the spatial distribution of the isotropic component of galactic soft X-ray depends largely on their energy, but proportional counters have not enough energy resolution to resolution to resolve the soft X-ray energy. To improve the energy resolution, filters have been used. In this observation, the K-absorption edges of boron (0.18 keV) and polypropylene (0.28 keV) were utilized as the filters to resolve X-ray energy. The effective area of the proportional counter was 600 cm², and the collimating field of view was 3 deg x 10 deg. The K-9M-50 rocket was launched on Jan. 23, 1975. The data on galactic soft X-ray between 0.1 and 2 keV are being analyzed, but the energy spectrum measured is presented. (J.P.N.)

[en] In the lunar occulation in 1964, Friedman et al. observed the size of Crab Nebula X-ray source by X-ray between 2 and 8A, and the extent of the X-ray source was about one eight year. In the present observation, the one-dimensional structure analysis of the Crab Nebula was made in the hard X-ray energy range. Eight NaI(Tl) scintillation counters were baloon-borne at Hyderabad balloon center, India on Jan. 24, 1975. The total effective area was 970 cm², and hard X-ray between 20 and 80 keV was detected. The center of the X-ray source was at 6 in.+-4 in. westward from the pulsar center, and this result was in good agreement with that by MIT group. (J.P.N.)