A Wide Field CCD Survey for Low Surface Brightness Galaxies:I.Data Acquisition, Description, and Initial Results

A low surface brightness (LSB) galaxy survey of the Cancer and Pegasus galaxy clusters and the low density regime defined by the Great Wall, was undertaken between 1993 October 14 and 1996 April 17 using the University of Texas MacDonald Observatory 0.8 m telescope and a Loran-Fairchild 2048 X 2048 CCD camera. 127 galaxies were found with μ_B(0)≥22.0 mag/arcsec², 119 of which are previously unidentified. Structural parameters [μ_B(0), α, r₂₅, etc.] and colors (Johnson/Cousins U, B, V, I, & R, when possible) were determined for the galaxies. The majority of these galaxies (80%) were well fit by an exponential profile, while the remaining were either fit by a king profile (17%) or were too clumpy to be fit by any curve (3%). None of the galaxies were fit by a de Vaucouleurs (1959) r^¼-type profile. The average central surface brightness of the sample is 23.06±0.20 mag/arcsec². The central surface brightness distribution of the galaxies is flat from 22.0μ_B(0) to 24.0μ_B(0), at which point a sharp dropoff is observed. By eliminating the possibility the dropoff is due to selection or distance effects, we show that it is highly likely the drop off is due to the inability for extremely LSB galaxies to form in the cluster environment. Finally, previous data have shown that LSBs are deficient in molecular gas and dust. If we assume that LSBs have no dust and correct the sample to face-on surface brightness, the lowest surface brightness disk we detected has μ_B(0)=27.1. However, this sample shows the same noncorrelation between inclination and central surface brightness that is seen for the case of high surface brightness galaxies. This noncorrelation has been used as an argument to support the notion that disk galaxies are optically thick. Since its extremely unlikely that LSBs are optically thick (i.e., none are IRAS sources) this noncorrelation most likely reflects the large intrinsic range of disk galaxy surface brightness instead of variations in disk galaxy opacity.