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Session 54 - Large Scale Structure.
Display session, Tuesday, January 16
North Banquet Hall, Convention Center
We present preliminary results for the angular autocorrelation function of galaxies, ømega(\theta), evaluated on scales of 0.01^\circ \lo \theta \lo 3^\circ, based on galaxy catalogs from the digital version of the POSS-II (DPOSS). The dataset used for this analysis consists of order 3\times 10^5 galaxies in an area near the North Galactic Cap which were obtained from 10 contiguous survey fields covering an area of order 340 square degrees. The magnitudes of galaxies detected from scans of the IIIa-J plates have been calibrated to Gunn g using both CCD calibration frames for each individual plate and matching of common objects in regions of overlap between plates. Using this technique, the estimated error in the zero point of the magnitude scale is of order 0.03. The limiting magnitude that is set by accurate classification of objects is g\simeq 20.5 and results for ømega(\theta) for galaxies with 17^m \lo g \lo 20.5^m will be presented. This is a fainter limiting magnitude than that of the APM survey (b_J = 20.5) and after rescaling our results to an equivalent limiting magnitude a direct comparison of the two results will be made. In particular, a scale of \sim 3^\circ for the DPOSS ømega(\theta) corresponds to \sim 8^\circ at the depth of the Lick survey, the scale on which the standard CDM model has been reported to fail badly. Additional preliminary results for ømega(\theta) for galaxy catalogs obtained from two somewhat smaller sets of contiguous fields, calibrated to Gunn r and i, will also be presented. As more plates are processed it is hoped that through measures of galaxy and cluster clustering DPOSS will serve to constrain strongly theories of large-scale structure formation.
