The Ninth Catalog of Spectroscopic Binary Orbits (SB9) continues the series of compilations of spectroscopic orbits carried out over the past 35 years by Batten and collaborators, e.g., the 8th SBO Catalog (SB8, <a href="https://cdsarc.cds.unistra.fr/ftp/cats/V/64">CDS Catalog V/64</a>) of Batten, Fletcher and MacCarthy 1989, Publ. DAO, 17, 1. This catalog is regularly updated. This version of SB9 contains orbits for over three thousand binary systems; notice that the numbers of orbits and binary systems included in this version differ from those in the reference publication, as the latter reflected the 2004 May 1 status of the catalog, when it had 2694 orbits for 2386 binary systems. There is an online version of this catalog, maintained by the authors, which is continuously updated, at <a href="http://sb9.astro.ulb.ac.be/">http://sb9.astro.ulb.ac.be/</a>;. This table was created by the HEASARC based on the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/B/sb9">CDS Catalog B/sb9</a>, using the files main.dat, alias.dat, orbits.dat and notes.txt. The CDS updates it regularly, and this HEASARC version is accordingly updated within a week of such updates. This is a service provided by NASA HEASARC .