def plot_on_region(ax=None, **kwargs):
"""Plot target regions"""
from gammapy.spectrum import SpectrumExtraction
ax = plot_exclusion_mask() if ax is None else ax
val = read_yaml(SpectrumExtraction.REGIONS_FILE)
on_region = SkyCircleRegion.from_dict(val['on_region'])
on_region.plot(ax, **kwargs)
return ax
