Wide-field multi-color photometry of the Galactic globular cluster NGC
  1261
  (Abriged)This work studies in more detail the stellar population, including
its photometric properties and characteristics, in the rarely studied southern
Galactic globular cluster NGC 1261. We focus on the brighter sequences of the
cluster's color-magnitude diagram (CMD). Like in our previous works, we rely
upon photometry in several passbands to achieve more reliable results and
conclusions. We carried out and analyzed new multi-color photometry of NGC 1261
in UBVI reaching below the turnoff point in all passbands in a fairly extended
cluster field, about 14'x14'. We found several signs of the inhomogeneity
("multiplicity") in the stellar population. The most prominent of them are: (1)
the dependence of the radial distribution of sub-giant branch (SGB) stars in
the cluster on their U magnitude, with brighter stars less centrally
concentrated at the 99.9 \% level than their fainter counterparts; (2) the
dependence of the location of red giant branch (RGB) stars in the U-(U-B) CMD
on their radial distance from the cluster center, with the portion of stars
bluer in the (U-B) color increasing towards the cluster outskirts.
Additionally, the radial variation of the RGB luminosity function in the bump
region is suspected. We assume that both the SGB stars brighter in the U and
the RGB stars bluer in the (U-B) color are probably associated with blue
horizontal branch stars, because of a similarity in their radial distribution
in the cluster. We estimated the metalicity of NGC 1261 from the slope of the
RGB in U-based CMDs and the location of the RGB bump on the branch. These
metallicity indicators give [Fe/H]zw = -1.34 +/- 0.16 dex and [Fe/H]zw = -1.41
+/- 0.10 dex, respectively. We isolated 18 probable blue straggler candidates.
They are more centrally concentrated than the lower red giants of comparable
brightness at the 97.9 \% level.
