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We present colour transformations for the conversion of the {em 2MASS} photometric system to the Johnson-Cousins $UBVRI$ system and further into the {em SDSS} $ugriz$ system. We have taken {em SDSS} $gri$ magnitudes of stars measured with the 2.5-m telescope from $SDSS$ Data Release 5 (DR5), and $BVRI$ and $JHK_{s}$ magnitudes from Stetsons catalogue and citet{Cu03}, respectively. We matched thousands of stars in the three photometric systems by their coordinates and obtained a homogeneous sample of 825 stars by the following constraints, which are not used in previous transformations: 1) the data are de-reddened, 2) giants are omitted, and 3) the sample stars selected are of the highest quality. We give metallicity, population type, and transformations dependent on two colours. The transformations provide absolute magnitude and distance determinations which can be used in space density evaluations at short distances where some or all of the {em SDSS} $ugriz$ magnitudes are saturated. The combination of these densities with those evaluated at larger distances using {em SDSS} $ugriz$ photometry will supply accurate Galactic model parameters, particularly the local space densities for each population.
We derive transformation equations between GALEX and UBV colours by using the reliable data of 556 stars. We present two sets of equations; as a function of (only) luminosity class, and as a function of both luminosity class and metallicity. The meta
Template fits to observed galaxy fluxes allow calculation of K-corrections and
We carried out an optical polarimetric study in the direction of the RCW95 star forming region in order to probe the sky-projected magnetic field structure by using the distribution of linear polarization segments which seem to be well aligned with t
We present JHKs near-infrared CCD photometric study for the Galactic open clusters NGC 1641 and NGC 2394. These clusters have never been studied before, and we provide, for the first time, the cluster parameters; reddening, distance, metallicity and
Based on a carefully constructed sample of dwarf stars, a new optical-near infrared photometric calibration to estimate the metallicity of late-type K and early-to-mid-type M dwarfs is presented. The calibration sample has two parts; the first part i