CCD photometry of the jet in M87: New features revealed

CCD photometry of the jet in the Thuan-Gunn r and g filters obtained under good seeing conditions is presented. Elliptical models of the underlying stellar emission were subtracted from the reduced and calibrated images. The high signal to noise ratio and good spatial resolution make it possible to determine very accurately the morphological properties of the jet. These observations reveal a number of new features: the outermost knot (H) can be resolved into several components, and the spectral index of the knots between the r and g bands is in general steeper than in that in the radio and shows a trend to become steeper with distance from the nucleus. The implications of these results for current radiation jet models will be briefly discussed.