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==> Time for this proposal is to be transferred from JBRAINE.PROP_2
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We propose deep SWS01 and LWS01 spectral scans of the nuclei of NGC 660.
The goal is to obtain a template for the emission of an old merger or
post-starburst galaxy (see justification).  No similar objects are
currently scheduled or reserved for ISO spectral line observations so
these data should be unique.
The choice of NGC 660 is based upon
* * the presence of a polar ring indicating that a strong interaction
or merger has taken place.  An estimate of the age is 1 - 3 billion years.
* * the presence of two nuclei separated by 4" or 250 pc detected in
radio continuum amd in the CO lines.  Modeling of the interferometric
visibilities rules out a thin torus and suggests that the maxima are
true nuclei.
* * the moderate current Far-IR luminosity, about 2 x 10^10 Lsun, along
with a merger age >= 10^9 years and the large amount of dust and
concentrated CO emission, suggests that much of the star formation to
occur as a result of the merger has already occurred.
* * NGC 660 is a very local galaxy (850 km/s).  If placed at the distance
of Arp 220 (5400 km/s), nobody would have noticed it.
* * the proximity of NGC 660 is that many lines should be quite strong and
the spectrum of high quality.  The signal-to-noise ratio should compare
favorably (or similarly) to the SWS observations presented by Kunze et
al. of NGC 4038/9 (interaction in an early stage) and to our LWS
observations of NGC 4414 where about 10 lines were detected in the
disk of this isolated spiral.