2MASS wide field extinction maps: IV. The Orion, Mon 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 ~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 dOrion A = (371 +/- 10) pc, dOrion B = (398 +/- 12) pc, dMon R2 = (905 +/- 37) pc,dRosette = (1330 +/- 48) pc, and $dCMa = (1150 +/- 64) pc, values that compare very well with independent estimates.