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

We present a near-infrared extinction map of a large region (approximately 2200 deg(2)) 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 similar to 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-sigma 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 d(OrionA) = (371 +/- 10) pc, d(OrionB) = (398 +/- 12) pc, d(MonR2) = (905 +/- 37) pc, d(Rosette) = (1330 +/- 48) pc, and d(CMa) = (1150 +/- 64) pc, values that compare very well independent estimates.