view Abstract Citations (8) References (7) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS New Plate Constants for the Northern Hyderabad Zone (+35 deg to +40 deg) of the Astrographic Catalogue, in Part Computed by the Plate Overlap Method Eichhorn, Heinrich ; Gatewood, George D. Abstract Positions from the AGK2 have been used to determine improved plate constants for the Northern Hyder- abad zone of the Astrographic Catalogue (ACHN), which contains measurements on plates centered at +360, +370, +380, and +390 A considerable amount of experimenting with various models for the re- lationship between measured and standard coordinates suggested that the best model (in the sense of leading to the systematically most accurate positions) for this relationship was one that is linear in the coordinates with provisions for linear magnitude equation and coma effect. One hundred and three out of a total of 592 plates were reduced by the overlap method, in sixteen groups of six plates each and one group of seven plates, the latter in the region of the open cluster NGC 752. The conventional plate constants (i.e., the co- efficients of x, y, and 1) can be obtained by the plate overlap method with the same accuracy as they would have been obtained by the conventional method using three times the number of reference stars, while the accuracy of the coma terms (coefficients of xd and yd in x and y, respectively), which vary significantly from plate to plate, increases on the average by a factor of 4.29 referred to the same number of reference stars. The accidental error of a position, obtainable from properly reduced measured coordinates on one plate is 0'.'28in andin . Publication: The Astronomical Journal Pub Date: November 1967 DOI: 10.1086/110399 Bibcode: 1967AJ.....72.1191E full text sources ADS |