Large Binocular Telescope observations of PSR J2043+2740*

We present the results of deep optical imaging of the radio/γ-ray pulsar PSR J2043+2740, obtained with the Large Binocular Telescope (LBT). With a characteristic age of 1.2 Myr, PSR J2043+2740 is one of the oldest (non-recycled) pulsars detected in γ-rays, although with still a quite high rotational energy reservoir (⁠E˙rot=5.6×1034 erg s−1). The presumably close distance (a few hundred pc), suggested by the hydrogen column density (NH ≲ 3.6 × 1020 cm−2), would make it a viable target for deep optical observations, never attempted until now. We observed the pulsar with the Large Binocular Camera of the LBT. The only object (V = 25.44 ± 0.05) detected within ∼3 arcsec from the pulsar radio coordinates is unrelated to it. PSR J2043+2740 is, thus, undetected down to V  ∼ 26.6 (3σ), the deepest limit on its optical emission. We discuss the implications of this result on the pulsar emission properties