We identify the extended Einstein IPC X-ray source, 1E0657-56, with a previously unknown cluster of galaxies at a redshift of z = 0.296. Optical CCD images show the presence of a gravitational arc in this cluster and galaxy spectra yield a cluster velocity dispersion of 1213 +352 −191 km s −1 . X-ray data obtained with the ROSAT HRI and ASCA indicate that 1E0657-56 is a highly luminous cluster in which a merger of subclusters may be occurring. The temperature of the hot gas in 1E0657-56 is kT = 17.4 ± 2.5keV, which makes it an unusually hot cluster, with important cosmological implications.Subject headings: galaxies: clusters:individual (1E0657-56) -intergalactic medium -large-scale structure of the universe -X-rays: galaxies

Interplanetary scintillation measurements of the disturbance factor, g, from October 1991 to October 1992 are used to construct synoptic Carrington maps. These maps, which show the structure of the quiet solar wind, are compared with X‐ray Carrington maps from the Yohkoh SXT instrument. For the period studied the global structure outlined by (weakly) enhanced g‐values apparent in the IPS maps tends to match the active regions (as shown in the X‐ray maps) significantly better than the heliospheric current sheet. Contrary to traditional opinion, which views active regions as magnetically closed structures that do not have any significant impact on the solar wind flow, our results suggest that density fluctuations in the solar wind are significantly enhanced over active regions. These results support the suggestion by Uchida et al. (1992), based on Yohkoh observations of expanding active regions, that active regions play a role in feeding mass into the quiet solar wind.