We present counts of galaxies to a completeness limit of B 25 from two 0.06 deg2 areas of sky, one at the South Galactic Pole and the other in a field at (l,b)= (21,-38)o. The fields were observed using a Tektronix 20482 CCD on the Du Pont 2.5 m at Las Campanas Observatory. Total integrations of from 9,000 to 25,000 seconds per filter were obtained in the UBVRI bands of the Johnson-Cousins system. The final, stacked images in each filter were calibrated using Landolt standard stars. Object detection was done with the FOCAS software package; but star/galaxy separation was accomplished through a combination of image profile parameters from FOCAS and DAOPHOT stellar point-spread-function fitting. This combination was used to create classification rules that varied with magnitude. We find differential galaxy count slopes of dlogA / dm in the UBVRI as 0.53 +/- 0.06, 0.39 +/- 0.07, 0.37 +/- 0.05, 0.28 +/- 0.06, and 0.28 +/- 0.07, respectively, where the errors given are the RMS about the mean linear fit. These slopes apply to the ranges 20.25 < U < 23.75, 20.75 < B < 23.75, 19.75 < V < 24.25, 17.25 < R < 24.25, and 17.75 < I < 24.25. Our count slopes are in good agreement with those in the same magnitude ranges published by Hogg et al. (1997, MNRAS, 288, 404) of 0.47 in the U; Driver et al. (1993, MNRAS, 266, 155) of 0.44 in the B; and Smail et al. (1995, ApJ, 449, L105) of dlogA/dV =0.40, dlogA/dR = 0.32, and dlogA/dI = 0.27. We also explore our sample of Lyman break objects and compare to previously derived luminosity functions for these high redshift objects. This work was supported by awards from the David and Lucile Packard Foundation and The Research Corporation.
American Astronomical Society Meeting Abstracts #195
- Pub Date:
- May 2000