It depends on the size of the ore body and the physical contrast ore/host rock. It is also depents on the quality and amount of ferromagnetic, paramagetic and diamagnetic minerals and their texture (grain morphology, intergrowth etc.)

HGD

Airborne magnetics will not detect gold or most of its associated elements. It will detect magnetite and pyrrhotite, so if the gold is associated with those minerals, near-direct detection is possible. The other major benefit of aeromagnetics is the delineation of fault structures and shear zones that might host gold deposits. Aeromagnetics is very useful for outlining regional geology.

An airborn magnetic survey is not a magic tool, which provides direct answers to your questions. The results of the survey may help you to identify drill locations if the survey has a proper planning and the survey method is suitable to your problem respectively the ore body. The results of the survey will be influenced by the 3D-structure of the ore body, the flying path of the plane and magnetic „noise“ in the surrounding (human and industrial settlements, bedrocks, to name a few problems).

You can discuss these questions/problems with a good geophysisist at the planning stage of the survey. Principally, the lead geophysisist of the surveying company should do the first assessment and processing of the data and can advise you on suitable software. However, if you do not have a solid knowledge of geophysics, you should not play with highly specialized software. Your task as an exploration geologist is to incorporate the results of the survey into a comprehensiv geological picture of a suspected ore body. And then get the lie detectors (=drillers) to do their job.

Gold doesn't respond to any geophysical method and this becomes more complicated during airborne magnetic surves where the sensor is, sometimes, far from magnetic sources. Airborne magnetic survey helps in mapping geological structures that might host minerals so, additional geophysical methods have to be used.