CA I've found the following ( at
Naval Terminology, Jargon and Slang FAQ ) , but as I'm not actually a 'Fly Navy' type of chap I can't personally vouch for the accuracy of the info.
Ball (the) - The glowing image projected by the FRESNEL LENS. Gives glideslope reference. Short for ‘meatball,’ the term for the red ball of light seen in the old mirror landing system which predated the fresnel lens system.
"Call the Ball" - A radio transmission from a pilot that he has sighted the BALL during approach to the carrier. Typically consists of SIDE NUMBER, aircraft type (to ensure proper ARRESTING GEAR settings), and amount of fuel onboard in thousands of pound s, e.g. '205 Tomcat ball, 3.5'.