Slothrop's brother Hogan

I am reading GR for the second time and am trying to remember if Slothrop's brother Hogan is mentioned aside from on viking page 184.6 as the source of the shirt he's wearing on the day he fends off Octopus Grigori. I have no recollection of even this mention of him from the first time and I couldn't find anything online either. I'm was intrigued by the idea of Slothrop's brother and want to know more about him.