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

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