UCAC4 Nearby Star Survey: A Search for Our Stellar Neighbors

We use data from the U.S. Naval Observatory fourth CCD Astrograph Catalog (UCAC4) in combination with photometry from the AAVSO Photometric All-Sky Survey (APASS) and Two Micron All-Sky Survey (2MASS) to identify stars within 25 pc of the Sun. A sample of nearby stars with accurate trigonometric parallaxes from the Research Consortium On Nearby Stars (RECONS) is used to generate a set of 16 new photometric color-$M_{K{_s}}$ relations that provide distance estimates with uncertainties of 15%. This work expands the available suites of well-calibrated photometric distance relations that can be used to identify nearby stellar systems. The distance relations are used with quality cuts to extract an initial sample of stars from the UCAC4 estimated to be within 25 pc. Color, proper motion and existing literature sources are then used to obtain a clean sample of red dwarfs, while limiting the amount of contamination from background giants, resulting in a sample of 1761 candidate nearby stars within 25 pc. Of these, 339 are new discoveries with no previously known published parallax or distance estimate, primarily with proper motions less than 0.2 arcsec/year. Five stars are estimated to be within 10 pc, with the nearest, TYC 3980 1081 1 with V$=$ 10.50, estimated to be at 5.93 pc. That several hundred new stars have been revealed so close to the Sun illustrates once again that there is considerable work yet to be done to map the solar neighborhood, and that additional nearby stars are likely still to be discovered.

UCAC3 Proper Motion Survey. II. Discovery Of New Proper Motion Stars In UCAC3 With 0.40 yr^-1 > mu >= 0.18 yr^-1 Between Declinations -47 deg and 00 deg

We present 474 new proper motion stellar systems in the southern sky having no previously known components, with 0.40 yr^-1 > mu >= 0.18 yr^-1 between declinations -47 deg and 00 deg. In this second paper utilizing the U.S. Naval Observatory third CCD Astrograph Catalog (UCAC3) we complete our sweep of the southern sky for objects in the proper motion range targeted by this survey with R magnitudes ranging from 9.80 to 19.61. The new systems contribute a ~16% increase in the number of new stellar systems for the same region of sky reported in previous SuperCOSMOS RECONS (SCR) surveys. Among the newly discovered stellar systems are 16 multiples, plus an additional 10 components that are new common proper motion companions to previously known objects. A comparison of UCAC3 proper motions to those from Hipparcos, Tycho-2, Southern Proper Motion (SPM4), and SuperCOSMOS indicates that all proper motions are consistent to ~10 mas/yr, with the exception of SuperCOSMOS. Distance estimates are derived for all stellar systems having SuperCOSMOS Sky Survey (SSS) B_J, R_59F, and I_IVN plate magnitudes and Two-Micron All Sky Survey (2MASS) infrared photometry. We find five new red dwarf systems estimated to be within 25 pc. These discoveries support results from previous proper motion surveys suggesting that more nearby stellar systems are to be found, particularly in the fainter, slower moving samples. In this second paper utilizing the U.S. Naval Observatory third CCD Astrograph Catalog (UCAC3) we complete our sweep of the southern sky for objects in the proper motion range targeted by this survey with R magnitudes ranging from 9.80 to 19.61.