2MASS wide field extinction maps. IV. The Orion, Monoceros R2, Rosette, and Canis Major star forming regions

Abstract. We present a near-infrared extinction map of a large region (approximately 2200 sq. deg) covering the Orion, the Monoceros R2, the Rosette, and the Canis Major molecular clouds. We used robust and optimal methods to map the dust column density in the near-infrared (Nicer and Nicest) towards ~19 million stars of the Two Micron All Sky Survey (2MASS) point source catalog. Over the relevant regions of the field, we reached a 1-σ error of 0.03 mag in the K-band extinction with a resolution of 3 arcmin. We measured the cloud distances by comparing the observed density of foreground stars with the prediction of galactic models, thus obtaining dOrionA = (371 ± 10) pc, dOrionB = (398 ± 12) pc, dMonR2 = (905 ± 37) pc, dRosette = (1330 ± 48) pc, and dCMa = (1150 ± 64) pc, values that compare very well with independent estimates.