NICMOS narrowband images of OMC-1

We present images of a 90 " x 90 " field centered on the Becklin-Neugebauer object (BN) in OMC-1, taken with the Near-Infrared Camera and Multiobject Spectrometer (NICMOS) aboard the Hubble Space Telescope. The observed lines are H-2 1-0 S(1), Pa alpha, [Fe II] 1.64 mu m, and the adjacent continua. The region is rich in interesting structures. The most remarkable are streamers of H-2 emission that extend from 15 " to 50 " from IRc2, seen here in unprecedented detail. Unlike the northern H-2 "fingers," these inner structures do not exhibit significant [Fe II] emission at their tips, which we suggest is due to lower excitation. These observations also show that the morphological details of the Pa alpha and [Fe II] emission (both imaged for the first time in this region) bear a striking resemblance to that of the H alpha and [S II] emission previously observed with WFPC2. This implies that these IR and optical lines are produced by radiative excitation on the surface of the molecular cloud. The Pa alpha morphology of III-I 202 is also very similar to its H alpha and [O III] emission, again suggesting that the extended Pa alpha emission in this object is photoexcited by the Trapezium, as has been suggested for the optical emission. We find evidence of shock-excited [Fe II] in HH 208, where it again closely follows the morphology of [S II]. There is also H-2 coincident with the [S II] and [Fe II] emission, which may be associated with HH 208. Finally, we note some interesting continuum features: diffuse "tails" trailing from IRc3 and IRc4, more extensive observations of the "crescent" found by Stolovy et al., and new observations of a similar oval object nearby. We also find a V-shaped region that may be the boundary of a cavity being cleared by IRc2.