This study calculated astrophysical parameters, as well as kinematic and galactic orbital parameters, of the open clusters NGC 1664 and NGC 6939. The work is based on CCD ultraviolet, blue, and visual (UBV) and Gaia photometric and astrometric data from ground- and space-based observations. Considering Gaia Early Data Release 3 (EDR3) astrometric data, we determined membership probabilities of stars located in both of the clusters. We used two-color diagrams to determine the E(B − V) color excesses for NGC 1664 and NGC 6939 as 0.190 ± 0.018 and 0.380 ± 0.025 mag, respectively. Photometric metallicities for the two clusters were estimated as [Fe/H] = −0.10 ± 0.02 dex for NGC 1664 and as [Fe/H] = −0.06 ± 0.01 dex for NGC 6939. Using the reddening and metallicity calculated in the study, we obtained distance moduli and ages of the clusters by fitting parsec isochrones to the color–magnitude diagrams based on the most likely member stars. Isochrone fitting distances are 1289 ± 47 pc and 1716 ± 87 pc, which coincide with ages of 675 ± 50 Myr and 1.5 ± 0.2 Gyr for NGC 1664 and NGC 6939, respectively. We also derived the distances to the clusters using Gaia trigonometric parallaxes and compared these estimates with the literature. We concluded that the results are in good agreement with those given by the current study. Present-day mass function slopes were calculated as Γ = −1.22 ± 0.33 and Γ = −1.18 ± 0.21 for NGC 1664 and NGC 6939, respectively, which are compatible with the Salpeter slope. Analyzes showed that both of clusters are dynamically relaxed. The kinematic and dynamic orbital parameters of the clusters were calculated, indicating that the birthplaces of the clusters are outside the solar circle.

Bu çalışmada, NGC 1664 ve NGC 6939 açık kümelerinin CCD UBV ve Gaia fotometrik ve astrometrik verileri kullanılarak temel astrofizik parametreleriyle birlikte kinematik ve dinamik yörünge parametreleri hesaplanmıştır. Gaia Erken Veri Sürümü 3 (EDR3) kataloğundaki astrometrik veriler dikkate alınarak, iki küme alanında bulunan yıldızların üyelik olasılıkları belirlenmiştir. NGC 1664 ve NGC 6939 için E(B-V) renk artıkları, sırasıyla, 0.190(0.018) ve 0.380(0.025) kadir hesaplanmıştır. NGC 1664 ve NGC 6939'un fotometrik metal bolluklarının tayininde, iki kümeye üye orta tayf türünden anakol yıldızlarının UBV fotometrik verileri dikkate alınmış olup, Karaali ve diğ. (2011)'nin fotometrik metal bolluğu bağıntısı kullanılmıştır. NGC 1664 ve NGC 6939 açık kümelerinin metal bollukları [Fe/H], sırasıyla, -0.10(0.02) dex ve -0.06(0.01) dex hesaplanmıştır. Çalışmada belirlenen renk artığı ve metal bolluğu değerleri kullanılarak, en olası üye yıldızlardan oluşturulan renk-parlaklık diyagramlarına PARSEC eş-yaş eğrileri fit edilmiş ve NGC 1664 ile NGC 6939 kümelerinin uzaklıkları (d) ve yaşları (t), sırasıyla, (1289(47) pc, 675(50) Myıl) ve (1726(87) pc, 1.5(0.2) Gyıl) hesaplanmıştır. NGC 1664 ve NGC 6939'un kinematik ve dinamik yörünge parametreleri tayin edilmiş ve iki kümenin de doğum yerlerinin Güneş çemberi dışında olduğu belirlenmiştir.

In this study, the structural and basic astrophysical parameters of poorly studied open cluster Berkeley 6 is calculated. Analyses of the cluster are carried out using the third photometric, spectroscopic and astrometric data release of Gaia (Gaia DR3). The membership probabilities of stars located through the cluster region are calculated by considering their astrometric data. Thus, we identified 119 physical members for Berkeley 6. The colour excess, distance and age of the cluster are determined simultaneously on the colour-magnitude diagram. We fitted solar metallicity PARSEC isochrones to the colour-magnitude diagram by considering the most probable member stars and obtained E(GBP-GRP) colour excess as 0.918±0.145 mag. Distance and age of the cluster are determined as d=2625±337 pc and t=350±50 Myr, respectively.