Yes, I know the Harpoon is a fire and forget missile (more better described as Automatic Target Acquisition):
From http://www.designation-systems.net/dusrm/m-84.html (open source)
"The latest (2002) upgrade of the AGM-84H/K SLAM-ER is the SLAM-ER ATA (Automatic Target Acquisition). This missile can be launched in the general direction of the target and will automatically select a target by comparing the stored reference image with the IIR seeker image without the need for operator intervention. However, the operator can take over control of the missile at any time in the mission, thereby retaining the capabilities of the basic SLAM-ER. (Note: this implies the operator has real time tracking information of the missile). The ATA system was released to the Fleet in 2002, and existing AGM-84H/K missiles will eventually be upgraded.
In January 2008, the U.S. Navy awarded Boeing an SDD (System Design and Development) contract for the AGM-84M Harpoon Block III. The Block III upgrade includes the major Block II features like the GPS/INS guidance and a new seeker, and adds a two-way datalink. The datalink makes it possible to update the targeting information after launch and actively control the missile at all points of the mission. The Navy plans to acquire Block III upgrade kits for 850 Harpoon missiles, with IOC planned for 2011. The RGM-84M is the ship-launched variant of the Block III missile."
The point I was making was that the missile itself out -ranges the CF-18's radar, but initial target information from the APG/73 could provide inputs from the operator if targets of opportunity are to be engaged rather than pre-planned/pre-programmed launches/strikes. After the missile is launched, it can of course find its way with precision however with newer versions the operator can take control of the missile if necessary. I'm not sure a single seat CF-18 pilot would want to do that (with all the other simultaneous tasks ongoing) but certainly an Aurora or other similar aircraft would, especially if a volley is fired by multiple aircraft and there are moving targets or an abort is required.
From Janes:
"A modification of the existing AGM-84D Harpoon Block 1C missile, the Block II+ weapon is being developed as a rapid-capability enhancement for the F/A-18E/F Super Hornet for introduction in late fiscal year 2017 (FY 2017). Block II+ introduces a GPS guidance kit, a new datalink interface that enables in-flight updates, improved target selectivity, an abort option, and enhanced resistance to electronic countermeasures to confer the Harpoon weapon with the ability to receive in-flight updates that improve the targeting and engagement of moving maritime targets."
(It's my understanding that the in-flight updates and changes to acquire new targets or re-attack (missed, obscured or moved targets?) need not be sent to the missile in flight by the original launch platform but can be sent or directed from another platform.)
