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We present new isochrone fits to colour-magnitude diagrams of the Galacticglobular clusters NGC\,288, NGC\,362, and NGC\,6218 (M12). We utilize a lot ofphotometric bands from the ultraviolet to mid-infrared by use of data from the{\it HST}, {\it Gaia}, unWISE, Pan-STARRS, and other photometric sources. Inour isochrone fitting we use theoretical models and isochrones from theDartmouth Stellar Evolution Program and Bag of Stellar Tracks and Isochronesfor $\alpha$-enhanced abundance [$\alpha$/Fe]$=+0.40$, different heliumabundances, and a metallicity of about [Fe/H]$=-1.3$ adopted from theliterature. We derive the most probable distances $8.96\pm0.05$, $8.98\pm0.06$,and $5.04\pm0.05$ kpc, ages $13.5\pm1.1$, $11.0\pm0.6$, and $13.8\pm1.1$ Gyr,extinctions $A_\mathrm{V}=0.08\pm0.03$, $0.11\pm0.04$, and $0.63\pm0.03$ mag,and reddenings $E(B-V)=0.014\pm0.010$, $0.028\pm0.011$, and $0.189\pm0.010$ magfor NGC\,288, NGC\,362, and NGC\,6218, respectively. The distance estimatesfrom the different models are consistent, while those of age, extinction, andreddening are not. The uncertainties of age, extinction, and reddening aredominated by some intrinsic systematic differences between the models. However,the models agree in their relative age estimates: NGC\,362 is $2.6\pm0.5$ Gyryounger than NGC\,288 and $2.8\pm0.5$ Gyr younger than NGC\,6218, confirmingage as the second parameter for these clusters. We provide reliable lists ofthe cluster members and precise cluster proper motions from the {\it Gaia}Early Data Release 3.

Isochrone fitting of Galactic globular clusters -- III. NGC\,288, NGC\,362, and NGC\,6218 (M12)