The process that gives rise to the locus ceruleus. This process pertains to the initial formation of a structure from unspecified parts. In mice, the locus ceruleus is a dense cluster of neurons within the dorsorostral pons. This nucleus is the major location of neurons that release norepinephrine throughout the brain, and is responsible for physiological responses to stress and panic. [ GOC:dgh GOC:cls http://purl.obolibrary.org/obo/go/references/0000021 GOC:jid http://openisbn.com/search.php?q=0838580343&isbn=1/ GOC:dph ]