The AGK3 provides positions and proper motions for stars north of -2.5 degrees. For the most part, it contains the stars in the AGK2 but is based on newly remeasured reference stars whose positions were reduced to the FK4 system. A list of 446 AGK2 stars not in the AGK3 and of three new stars is provided. All plates were taken at the Bergedorf Observatory. In addition to the positions and proper motions, the catalog contains magnitudes and spectral types, the epoch of the observations, the epoch difference between the AGK2 and AGK3, and the BD numbers. Introduction: The AGK3 Star Catalogue of Positions and Proper Motions North of -2.5 Degrees Declination (hereinafter AGK3) was conceived and planned during discussions between O. Heckmann and D. Brouwer at Hamburg Observatory following the 1952 International Astronomical Union (IAU) General Assembly in Rome. It was concluded that an adequate number of reference stars (AGK3R) should be observed by as many meridian circles of as many observatories as possible, the revision of FK3, then in progress (FK4), should define the reference frame, and the same instruments as used for AGK2 should be used for the observations for AGK3. A formal recommendation was adopted through Commission 8 at the 1955 IAU General Assembly in Dublin, with the observatories at Babelsberg, Bergedorf, Bordeaux, Greenwich, Heidelberg, Nikolajew, Ottawa, Paris, Pulkovo, Strasbourg and Washington (USNO) to collaborate in the work, and with F. P. Scott (USNO) to coordinate the meridian circle observations of AGK3R stars. The completion of the photographic observations was to be the responsibility of the observatories at Bergedorf and Bonn, with all plate measurements to be done at the former. (However, it was finally decided that all plates, even for the AGK2 Bonn zones, would be taken at Bergedorf.) The plates for AGK3 were secured at Bergedorf between August 1956 and June 1964, with special precautions (exposures on both sides of the pier) made to compensate for possible changes in the camera objective. The two sets of plates were measured at Bergedorf in opposite directions and averaged to obtain final x,y coordinates. The detailed procedures for the correction of magnitude-color errors, reduction of the measures using the AGK3R stars, re-reduction of AGK2 using its reference catalog AGK2A transformed to the FK4 system, and final reduction of the AGK3 positions and proper motions, are discussed by W. Dieckvoss in his technical introduction to the source reference. Although a more detailed discussion of errors is given by Dieckvoss, the standard error for one coordinate on one plate as determined from a limited sample of 110 pairs of plates is +/- 0.025" for AGK3.
Cone search capability for table I/61B/agk3 (Catalog Data)
