Speculation north of the border and on Tyneside is adamant that the Scottish giants want to lure Harper to Parkhead when the transfer window reopens in January.
Harper has struggled to secure regular first-team football throughout his Newcastle career and has made just 57 appearances in a decade at St James' Park.
The 28-year-old has been restricted to just two outings this term and hinted in the autumn that it may be time to quit his native North East.
The continued impressive form of Shay Given means Harper has little chance of forcing his way into Sir Bobby Robson's starting XI.
That has prompted Celtic to weigh up a New Year swoop for the highly-rated shot-stopper and Harper may jump at the chance of regular playing time.
Scotland international Rob Douglas' future at Parkhead remains shrouded in doubt while Magnus Hedman's performances in recent weeks have not enamoured manager Martin O'Neill.
The Bhoys chief is understood to be scouring for goalkeeping reinforcements and Harper has emerged as the man to satisfy O'Neill's demands.
