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I want to create an IRS spectral map using two different modules -- Why are the slits centered on different parts of the sky?
Posted by z-Vandana Desai on 01 December 2008 02:39 PM
An example of the problem using the SH and LH slits is illustrated here:  http://ssc.spitzer.caltech.edu/files/spitzer/n1365_irs_sh_lh.jpg.

The spectral map positions are in array coordinates, which have axes that are parallel and perpendicular to the slit in question. Because the slits are not exactly parallel (or perpendicular) to each other, the map positions are not exactly in the same places either. For example, the SL and SH modules are nearly 45 degrees with respect to each other, so the map positions are not at all the same.