Contours of the Hα emission of the two brightest H II regions in Clump1, C1a, and C1b, are overplotted in green to the GALEX-FUV continuum image in the left panel and to the HST-ACS-F606W optical image in the right panel. Contour levels are: 2.5, 4, 6, 10, 20 × 10⁻²⁰ erg s⁻¹ cm⁻² per pixel (0.2″). The radius of the 10 × 10⁻²⁰ erg s⁻¹ cm⁻² contour level is about 70 and 50 pc for C1a and C1b respectively. The HST image shows that only part of the stellar population in the cloud is emitting ionizing photons powering the Strömgren spheres.