Depiction of the largely featureless region, dubbed the “isochrone blindspot”. It covers an age span of approximately 100 − 500 Myr and roughly 0 − 12 G magnitudes in the Gaia passbands. The plot features PARSEC isochrones (Bressan et al. 2012) with default parameters. The dashed line indicates the upper main sequence region where observed sources are rare, while the dash-dotted line delineates the lower main sequence, which is a region of interest regarding the information gained through empirical isochrones.