J/AJ/114/850 J/AJ/114/850 Errors in the FK5 Catalog R C Stone Astron. J. 114 850 1997 1997AJ....114..850S I/149A : Fifth Fundamental Catalogue (FK5) Part I (Fricke+, 1988) I/175 : Fifth Fundamental Catalogue (FK5) - Extension (Fricke+ 1991) Fundamental catalog Positional data This paper presents new positions for 689 FK5 stars determined directly in the extragalactic reference system from CCD scan observations made with the Flagstaff Astrometric Scanning Transit Telescope (FASTT). All the observations were made in 1994-1996 with an accuracy of ~+/-40mas in each coordinate. When these positions are compared with their counterparts in the FK5 catalog, systematic errors in the FK5 are found that vary in both right ascension and declination and can be as large as 100 mas in magnitude. No magnitude-dependent errors in the FK5 were found. Moreover, the true error in FK5 star positions is determined to be ~+/-80mas in both coordinates or two times the expected catalog positional errors. There is an excellent agreement between the systematic errors in the FK5 found in this paper and those presented in Lindegren et al. (1995A&A...304...44L) comparing FK5 and Hipparcos 30-month star positions. By comparing corresponding FASTT and FK5 star positions, the link between the optical and extragalactic reference frames was determined and is given by the following rotations ({omega}_x_,{omega}_y_,{omega}_z_) = (3+/-5, 25+/-5, 16+/-4) (s.e.) mas, which agree well with previous determinations made by other investigators. Two of the rotations ({omega}_y_,{omega}_z_) are significantly larger than their standard errors and, therefore, presumably real. Finally, since these rotations are small (<=25mas), the FK5 and extragalactic reference frames must be closely aligned to one another.

Seq Running number --- FK5 FK5 star number (Cat. <I/149>, <I/175>) --- HD HD designation --- Vmag V magnitude taken from FK5 catalog mag RAh Right ascension, J2000 h RAm Right ascension, J2000 min RAs Right ascension, J2000 s e_RAs Standard error in RA 10-4s o_RAh Number of times observed in RA --- EpRA-1900 Mean epoch of RA coordinate (+ 1900) yr pmRA Proper motion in RA taken from FK5 10-2s/yr DE- Declination sign --- DEd Declination, J2000 deg DEm Declination, J2000 arcmin DEs Declination, J2000 arcsec e_DEs Standard error in DE mas o_DEd Number of times observed in DE --- EpDE-1900 Mean epoch of DE coordinate (+ 1900) yr pmDE Proper motion in DE taken from FK5 10mas/yr CDS 1998Feb05AAS CD-ROM series, Volume 9, 1997 Lee Brotzman [ADS] 27-Sep-1997 J_AJ_114_850.xml