The image shows ROSAT HRI contours of RX J1347-1145 superposed on an optical NTT image, displaying a very compact cluster. In the optical image several arcs and arc candidates are visible (marked with letters), implying that the cluster acts as a gravitational lens.
Schindler, S., M. Hattori, D. M. Neumann, and H. Böhringer:
ROSAT/HRI and ASCA observations of the most luminous X-ray cluster RX J1347.5-1145
Astron. & Astrophys. 317, 646-655 (1997)
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