  Markarian (Mkn) 297 is a complex system with two interacting galaxies.
Observations were made with ISO using ISOCAM, ISOPHOT and LWS. We present
ISOCAM maps at 6.7, 7.7, 12 and 14.3 microns which, with PHT-S spectrometry of
the central interacting region, probe the dust obscured star formation and dust
properties. ISOCAM reveals that the strongest emission region in the four MIR
bands is completely unremarkable at visible and near-IR (e.g. 2MASS)
wavelengths, and does not coincide with the nuclear region of either colliding
galaxy. It shares this striking characteristic with the overlap region of the
colliding galaxies in the Antennae (NGC 4038, 4039), the intragroup region of
Stephan's Quintet, and IC 694 in the interacting system Arp 299. At 15 microns,
the hidden source in Mkn 297 is, respectively, 14.6 and 3.8 times more luminous
than the hidden sources in the Antennae (NGC 4038/4039) and Stephan's Quintet.
Numerical simulations indicate that we see the Mkn 297 interaction about 1.5 x
10e8 years after the collision. ISOCAM shows knots and ridges of emission. The
14.3/7.7 micron ratio map implies widespread strong star formation. Strong
emission features were detected in the ISOPHOT spectrum, while [OI], [OIII] and
[CII] emission lines were seen with LWS. Using data from the three instruments,
luminosities and masses for two dust components were determined. The total
infrared luminosity is approximately 10e11 L_sol, marginally a LIRG. A 1979
supernova generated one of the most powerful known radio remnants (SN 1982aa)
close to the strongest MIR source and identified with star forming region 14 in
the optical. This exceptional supernova explosion may have been accompanied by
a GRB, and a search for a GRB in this direction in contemporaneous satellite
data is recommended.
