000001861 001__ 1861
000001861 005__ 20160701171654.0
000001861 0247_ $$2DOI$$a10.1016/S0032-0633(98)00028-2
000001861 037__ $$aASTROimport-18
000001861 100__ $$aPauwels, T.
000001861 245__ $$aAstrometric reductions of ESO-Schmidt plates
000001861 260__ $$c1998
000001861 520__ $$aWe have performed a series of astrometric reductions of ESO-Schmidt plates. In this paper we compare the results of reductions with linear transformation formulae with the results of reductions with the full third degree transformation formulae. We find that there are only small differences between both reductions, provided that an equidistant projection is used between the sky and the tangential plane rather than the usual gnomonic projection, and that enough reference stars are used. These small differences are almost entirely due to the larger errors in the third-degree reduction, showing the superiority of linear transformation formulae over third degree formulae for ESO-Schmidt plates. Reductions using only stars from a certain magnitude class show that there is no measurable magnitude effect. And finally, comparing reductions using only one single plate with reductions using the mean measurements of seven plates show that taking the mean of seven plates does improve the positions. 
000001861 773__ $$c899-903$$i8$$pPlanetary and Space Science$$v46$$y1998
000001861 85642 $$ahttp://esoads.eso.org/abs/1998P%26SS...46..899P
000001861 905__ $$apublished in
000001861 980__ $$aREFERD