We study the optical properties of a large sample of galaxies in low-density regions of the nearby universe .
We make a 5 h ^ { -1 } Mpc-smoothed map of the galaxy density throughout the Center for Astrophysics Redshift Survey ( CfA2 , [ Geller & Huchra 1989 ] ) to identify galaxies within three prominent nearby “ voids ” with diameter \gtrsim 30 h ^ { -1 } Mpc .
We augment the CfA2 void galaxy sample with fainter galaxies found in the same regions from the deeper Century ( [ Geller et al .
1997 ] ) and 15R ( [ Geller et al .
2000 ] ) Redshift Surveys .
We obtain B and R CCD images and high signal-to-noise longslit spectra for the resulting sample of 149 void galaxies , as well as for an additional 131 galaxies on the periphery of these voids .

Here we describe the photometry for the sample , including B isophotal magnitudes and B - R colors .
For the 149 galaxies which lie in regions below the mean survey density , the luminosity functions in B and R are well-fit by Schechter functions with respective parameters ( \alpha _ { B } = -0.5 \pm 0.3 , B _ { * } = -18.9 \pm 0.2 ) and ( \alpha _ { R } = -0.9 \pm 0.3 , R _ { * } = -20.4 \pm 0.3 ) .
The B luminosity function ( LF ) is consistent with typical survey LFs ( e.g .
the Southern Sky Redshift Survey ; [ Da Costa et al .
1998 ] ) , and the R LF is consistent with the Century Survey .
The B and R LFs of 131 galaxies in the “ void periphery ” , regions between the mean density and twice the mean , have similar Schechter parameters .
The CfA2 LF is inconsistent with both samples at the 3.5 \sigma level .

When we narrow our analysis to the 46 galaxies in regions below half the mean density , the LF is significantly steeper : \alpha \sim - 1.4 \pm 0.5 .
The typical survey LFs are inconsistent with this subsample at the \sim 2 \sigma level .
The B - R color distribution of galaxies in the lowest-density regions is also shifted significantly ( \sim 3 \sigma ) blue-ward of the higher density samples .
The most luminous red galaxies ( R \lesssim - 21 ) are absent from the lowest density regions at the 2.5 \sigma level .