2005PASJ...57..203O

begin{HTML} We present a study of the newly discovered McNeil's nebula in Orion using simultaneous observations of the <i>JHK</i>_s-bands with the near-infrared (NIR) camera SIRIUS on the IRSF 1.4m telescope. The cometary infrared nebula is clearly seen extending toward both north and south from the NIR source (V1647 Orionis), which illuminates McNeil's nebula. The compact nebula has an apparent diameter of about 70''. The nebula is blue (bright in <i>J</i>) and has a cavity structure with two rims extending toward the north-east and the north-west. The north-east rim is brighter and sharp, while the north-west rim is diffuse. The north-east rim can be traced out to ∼ 40'' from the location of the NIR source. In contrast, no cavity structure can be seen toward the south, although the diffuse nebula is extended out to ∼ 20''. New NIR photometric data show a significant variation in the magnitudes (> 0.15 mag) of the source of McNeil's nebula within a period of one week, which is possibly under the phase of eruptive variables, like FUors or EXors.