Analysis of systematic effects and statistical uncertainties in angular clustering of galaxies from early sloan digital sky survey data

The angular distribution of galaxies encodes a wealth of information about large-scale structure. Ultimately, the Sloan Digital Sky Survey (SDSS) will record the angular positions of order of 108 galaxies in five bands, adding significantly to the cosmological constraints. This is the first in a series of papers analyzing a rectangular stripe of 25 × 90° from early SDSS data. We present the angular correlation function for galaxies in four separate magnitude bins on angular scales ranging from 0003 to 15°. Much of the focus of this paper is on potential systematic effects. We show that the final galaxy catalog—with the mask accounting for regions of poor seeing, reddening, bright stars, etc.—is free from external and internal systematic effects for galaxies brighter than r* = 22. Our estimator of the angular correlation function includes the effects of the integral constraint and the mask. The full covariance matrix of errors in these estimates is derived using mock catalogs with further estimates using a number of other methods.