Hi,

You can find these informations about 551.28nm and 588.865nm transition lines of W here :

http://physics.nist.gov/PhysRefData/ASD/lines_form.html

not all require data is given in NIST like transition probabilities of these lines

Try the Kurucz Atomic Line Database:

http://www.cfa.harvard.edu/amp/ampdata/kurucz23/sekur.html