Image Details
Caption: Figure 2.
Continuum-subtracted HST narrowband images around NGC 5408 X-1, with WFC3 F502N (left) for [O III] λ5007 and WFPC2 F656N (right) for Hα and [N II]. The images are smoothed with a Gaussian kernel of σ = 1 pixel. The ULX position is enclosed by the circle.
© 2026. The Author(s). Published by the American Astronomical Society.