... Time delay determinations in astrophysics are used most often to find time delays between flux density variations in different spectral bands and/or lines in AGNs, and different images of gravitationally lensed QSOs. ... OB used an idea to take into account the known gravitational lensing time delay to get combined radio and optical light curves and then to use them for determination of the possible radio-from-optical time delay. ... Correction for change of time delay and radio flux. ...