Fort Indiantown Gap is located northeast of Harrisburg, just north of I-81 (near where it links with I-78) . . . there is (and always has been) very frequent military air traffic associated with that base, especially big ol' helicopters, often flying in 2's or 3's . . . we see them probably at least weekly over here the Cumberland Valley (west of Harrisburg) . . . also, there are National Guard units at Harrisburg Airport - they fly the huge military transport props (I think the particular mission of this reserve unit involves electronic warfare of some type) . . .
Perhaps that was it.....Actually, for this being the capital- I've not seen much activity, at all.