Spirals Bridges and Tails: Pipeline


To correct some 'imperfections' in our pipeline reduced data we have used MOPEX to re-mosaic the BCD data. In some of our channel 4 (8.0 micron) data we could see horizontal bands (muxbleed). We wrote software to correct this banding. Below are some before and after pictures to illustrate.

To do the re-mosaicing we followed the example tutorial on the SSC website. However, we used a drizzle interpolation method with a drizzle factor of 1 instead of the default correction with FINERES set to 4.

Here are some sample namelist files that we used for the channel 3 (5.8 micron) re-mosaicing, mosiac.ch3.nl and overlap.ch3.nl. Here is a brief description of how to run the overlap and mosaic scripts. We used the same mosaicking scripts for both the MIPS and IRAC images.

The file fixband.pro is an example of the IDL script, written by William Reach, that we used to correct the banding in the channel 4 (8.0 micron) images. Here is a how to file with brief instructions on using the IDL script. To correct the banded images we fit the bands with polynomials on either side of the source and interpolated across the source.




Above is the pipeline version 13.2 channel 3 (5.8 micron) image of Arp 242. Notice the 'boxy' appearance and the large 'box' in the upper right. Notice also that none of the Arp 242 tidal features are visible.




Above is our re-mosaiced channel 3 (5.8 micron) image of Arp 242. The 'boxiness' as well as the 'box' in the upper right corner have been fixed. Notice also that tidal features can now be easily seen.





The image above on the right is the original Spitzer V13.2 pipeline post-bcd 24 micron image for Arp 72. The image on the left is from our new mosaicking. Note that the original pipeline produces a `3-tiered' effect in the background, that is, the background appears to be divided into thirds. The new mosaicking fixes this. This `3-tiered' effect appears quite frequently in our MIPS 24 micron pipeline post-bcd images. The stretch and color scale for the two images is the same.





Above is the pipeline version 13.2 channel 4 (8.0 micron) image of Arp 242. Notice the horizontal band (muxbleed).




Above is our re-mosaiced and debanded channel 4 (8.0 micron) image of Arp 242. Notice that the horizontal bands have been corrected.
 


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