NGC 3815. The submm emission to the NE and W of the galaxy is associated with
noisy bolometers. However, the arm-like submm structures seen extending from the
galaxy to the N and S are not. Both of these 'arms' extend in the direction of
faint optical features seen in DSS and Two-Micron All Sky Survey (2MASS) images.
The optical images also show evidence of extended optical emission around the
main optical extent (just visible to the NE in Fig. 1), but 2MASS (JHK) images
show a band of emission stretching E-W between two nearby galaxies on either
side of NGC 3815. It seems clear that some kind of interaction is taking place
in this system, and therefore it is perhaps not unlikely that there might also
be significantly extended submm emission.
See UGC 06632, UGC 06648
UGC 06674 at 13.6, 85