From the analysis of a ∼100 ks Chandra observation of the dwarf starburst galaxy NGC 1569, we have found that the X-ray point sources, CXOU 043048.1+645050 and CXOU 043048.6+645058, showed significant time variability. During this observation, the X-ray flux of CXOU 043048.1+645050 increased by 10 times in only 2 × 10 4 s. Since the spectrum in its bright phase was fitted with a disk blackbody model with kT in ≈ 0.43 keV and the bolometric luminosity is L bol ≈ 10 38 ergs s −1 , this source is an X-ray binary with a stellar mass blackhole. Since the spectrum in its faint phase was also fitted with a disk blackbody model, the time variability can be explained by a change of the accretion rate onto the black hole. The other variable source, CXOU 043048.6+645058, had a flat spectrum with a photon index of ∼1.6. This source may be an X-ray binary with an X-ray luminosity of several × 10 37 ergs s −1 . In addition, three other weak sources showed possible time variability. Taking all of the variability into account may suggest an abundant population of compact X-ray sources in NGC 1569.

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We analyzed discrete sources in a typical starburst galaxy, NGC 1808, with Chandra in order to study the relation between X-ray and star-forming activities. We detected thirty-eight X-ray sources with an X-ray luminosity ($L_{\rm X}$) of $\gt$ 10$^{37}$ erg s$^{-1}$ in the central 5$^{\prime}\times$5$^{\prime}$ (13.4 kpc $\times$ 13.4 kpc) region. About 90% of the hard X-rays previously detected with ASCA came from these discrete sources. Among the detected sources, sixteen sources had an $L_{\rm X}$ of $\gt$ 10$^{38}$ erg s$^{-1}$. The number of luminous sources is nearly equal to that of M 82, although their concentration into the central star-forming region is lower than that of M 82. There are several soft X-ray sources with a temperature of 0.6 keV in the central star-forming region. The X-ray properties of the soft sources are similar to those of a H II region, or a supernova remnant. The existence of both luminous sources and soft X-ray sources indicates the star-forming activity of NGC 1808. However, we detected only a few candidates of high-mass X-ray binaries that would be produced by enhanced star-forming activity. This may be due to the starburst age of NGC 1808.

We are studying on a press forming of a 0.3-mm-thick foil in order to make advanced thin-foil substrates with a twostage reflector for large X-ray telescopes. Aluminum alloy has been used as a material for thin-foil substrates. We propose a use of Mg foil as lightweight substrates, since more lightweight material is necessary for building the large telescopes. Furthermore, we are making a two-stage reflector with a stage 200 mm long, since a long substrate has an advantage for fabrication of large X-ray telescopes. After various experiments, we formed a Mg foil with a figure error of +/-20 µm. This large figure error can be removed by a replication method. We also made an evaluation system of an image quality by using a Newtonian telescope. The evaluation system can generate a collimated optical light with a diameter of 450 mm and with a parallelism of about 4". Using this system, we found that an image quality of our Mg foil was similar to that of the ASCA foils.