Optical extension of the 2MASS infrared catalog.

2MASS is the most complete, homogeneous, and least contaminated catalog among the deep all-sky catalogs of stellar data produced to date. These qualities allow it to be successfully used not only for astrophysical studies, but also for solving various problems of all-sky astrometry and for operational support of automated telescopes. However, the lack of optical photometry in the catalog prevents its potential from being completely unveiled. To overcome this shortcoming, we have developed a procedure for transforming the 2MASS near-infrared magnitudes to optical magnitudes R J relative to the UCAC2 magnitudes R U . As a result of applying this procedure, all 2MASS objects have gotten optical magnitudes with effective wavelengths between the V and R bands of the Johnson system. The resulting transformation accuracy $$ \varepsilon _{R_J } $$ < 05). We also give a brief overview of the present-day all-sky catalogs with emphasis on their photometric properties and completeness. [ABSTRACT FROM AUTHOR]