We present the galaxy two-point angular correlation function for galaxies selected from the seventh data release of the Sloan Digital Sky Survey .
The galaxy sample was selected with r -band apparent magnitudes between 17 and 21 ; and we measure the correlation function for the full sample as well as for the four magnitude ranges : 17 – 18 , 18 – 19 , 19 – 20 , and 20 – 21 .
We update the flag criteria to select a clean galaxy catalog and detail specific tests that we perform to characterize systematic effects , including the effects of seeing , Galactic extinction , and the overall survey uniformity .
Notably , we find that optimally we can use observed regions with seeing < 1 \aas@@fstack { \prime \prime } 5 , and r -band extinction < 0.13 magnitudes , smaller than previously published results .
Furthermore , we confirm that the uniformity of the SDSS photometry is minimally affected by the stripe geometry .
We find that , overall , the two-point angular correlation function can be described by a power law , \omega ( \theta ) = A _ { \omega } \theta ^ { ( 1 - \gamma ) } with \gamma \simeq 1.72 , over the range 0 \aas@@fstack { \circ } 005 – 10 \degr .
We also find similar relationships for the four magnitude subsamples , but the amplitude within the same angular interval for the four subsamples is found to decrease with fainter magnitudes , in agreement with previous results .
We find that the systematic signals are well below the galaxy angular correlation function for angles less than approximately 5 \degr , which limits the modeling of galaxy angular correlations on larger scales .
Finally , we present our custom , highly parallelized two-point correlation code that we used in this analysis .