It was most likely to have been S.A.B.S., Stabilising Automatic Bomb Sight. Harris rejected its use by the main force as it required the aircraft to remain straight and level for 10 miles leading up to the target. 617 specialised in its use. (see the chapter entitled 'Sniper Squadron' in Paul Brickhill's 'The Dambusters', 1951) One of the crews remarked on the poor accuracy achieved by 9 squadron on the final Tirpitz raid, saying, "After all, they were using the Mark XIV sight". See 'A Hell of a Bomb', Stephen Flower 2002, Tempus Publishing. Appendix 2 gives the bomb plot.
I can find no record of 617 ever using the Norden bombsite in any of my 36 books on the subject.