According to Jehovah's Witnesses, who or what is the Holy Spirit?

Traditional Christianity teaches that the Father, Son, and Holy Spirit are three distinct persons, coequal, coeternal, of the same substance, and all fully divine. The Holy Spirit is the same being referred to in the New Testament as the God's Spirit (e.g., 1 Corinthians 2:11, Ephesians 4:30) and as Christ's Spirit (e.g., Galatians 4:6, Philippians 1:19, 1 Peter 1:11), and in one place with both titles (Romans 8:9). My understanding of the Jehovah's Witnesses is that they believe God the Father to be fully divine and eternal, but Jesus Christ is his first creation, gifted with semi-divinity. What do they teach about the Holy Spirit? A good answer will address, directly or by clear implication, whether or not the Holy Spirit is: - eternal - eternally/ontologically distinct from God the Father - ontologically divine - a person - one and the same as the Spirit of Christ A good answer will address anything else that a standard JW articulation of the doctrine of the Holy Spirit would address and will use Watchtower sources.