The data holdings, usage and citation records of the NASA Astrophysics Data System (ADS) form a unique environment for bibliometric studies. Here we will highlight one such study. Using the citation and usage statistics from the NASA Astrophysics Data System, we study the impact of offering a paper as an electronic pre-print ("e-print") on the arXiv e-print repository, prior to its publication in a scholarly journal. We will address the following questions for astronomy: are people reading the e-prints from arXiv instead of the journal articles? Are e-prints read in a different way than journal articles? What is the impact of offering a paper as e-print prior to its publication in a scholarly journal? We will show that in astronomy, the e-prints are not being read instead of the journal article. As soon as the journal article is published, users prefer to read the article. Our analysis confirms that journal articles which were submitted as e-print on arXiv, prior to their publication, show higher citation rates than journal articles that were not submitted as e-print.