The Vela pulsar and its likely counter-jet in the K_s band

We report the first high spatial resolution near-infrared imaging of the Vela pulsar in the $K_s$ band obtained with the new adaptive optics system recently mounted on the Gemini-South telescope. For the first time, we have firmly detected the pulsar in this band with $K_s$ $\approx$ 21\fm8, and have resolved in detail an extended feature barely detected previously in the immediate vicinity of the pulsar in the $J_sH$ bands. The pulsar $K_s$ flux is fully consistent with the extension of the flat optical spectrum of the pulsar towards the infrared and does not confirm the strong infrared flux excess in the pulsar emission suggested earlier by the low spatial resolution data. The extended feature is about two times brighter than the pulsar and is likely associated with its X-ray counter-jet. It extends $\sim$ 2\asec southwards of the pulsar along the X-ray ounter-jet and shows knot-like structures and a red spectrum.