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Effective temperature scale and bolometric corrections from 2MASS photometry
We present a method to determine effective temperatures, angularsemi-diameters and bolometric corrections for population I and II FGKtype stars based on V and 2MASS IR photometry. Accurate calibration isaccomplished by using a sample of solar analogues, whose averagetemperature is assumed to be equal to the solar effective temperature of5777 K. By taking into account all possible sources of error we estimateassociated uncertainties to better than 1% in effective temperature andin the range 1.0-2.5% in angular semi-diameter for unreddened stars.Comparison of our new temperatures with other determinations extractedfrom the literature indicates, in general, remarkably good agreement.These results suggest that the effective temperaure scale of FGK starsis currently established with an accuracy better than 0.5%-1%. Theapplication of the method to a sample of 10 999 dwarfs in the Hipparcoscatalogue allows us to define temperature and bolometric correction (Kband) calibrations as a function of (V-K), [m/H] and log g. Bolometriccorrections in the V and K bands as a function of T_eff, [m/H] and log gare also given. We provide effective temperatures, angularsemi-diameters, radii and bolometric corrections in the V and K bandsfor the 10 999 FGK stars in our sample with the correspondinguncertainties.
| Precise positions in the FK4 system for 120 radio source reference stars
Positions are given in the FK4 system for 120 primary reference starsgrouped around the optical counterparts of 11 extragalactic radiosources. The observations were made in 1979 and 1980 with the 6-in.transit circle of the U.S. Naval Observatory. The results reported hererepresent the first step in a three-tiered process to determineastrometric positions of the optical counterparts referred to the systemof the FK4. One application of such positions is the determination of anearly inertial optical reference frame, which eventually may becompared to a reference frame at radio wavelengths.
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Observation and Astrometry data
| Constellation: | Libra |
| Right ascension: | 15h17m16.57s |
| Declination: | -08°37'31.0" |
| Apparent magnitude: | 9.321 |
| Proper motion RA: | -27.7 |
| Proper motion Dec: | -0.8 |
| B-T magnitude: | 9.772 |
| V-T magnitude: | 9.359 |
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