The Broad Band X-ray Telescope (BBXRT) was flown on the Space Shuttle Columbia (STS-35) on 1990 December 2-December 11, as part of the ASTRO-1 payload. The flight of BBXRT marked the first opportunity for performing X-ray observations over a broad energy range (0.3-12 keV) with a moderate energy resolution (typically 90 eV and 150 eV at 1 and 6 keV, respectively).
BBXRT was co-mounted with three ultraviolet telescopes HUT, WUPPE, and HIT for Astro-1 in 1990.
This was, "..the first focusing X-ray telescope operating over a broad energy range 0.3-12 keV with a moderate energy resolution (90 eV at 1 keV and 150eV at 6 keV)." according to NASA.