Knowledgebase: Spitzer: MIPS

Why can't I derive the 24 micron saturation values in Table 2.7 (from the MIPS Instrument Handbook) by sticking either 0 or large background levels into Table 2.8?

Trying to compare Tables 2.7 and 2.8 is like comparing apples and oranges. The values for truly (ideal) cases are in Table 2.7. The formulae in Table 2.8 actually describe the general case, which includes a combination of point and background flux, so they break down in the limiting cases. Further complicating matters, Table 2.8 also has incorporated into it subframes that are part of the observing sequence AND the impact of some substitution of values for point sources -- there is a half-second data frame taken at the beginning of the observing sequence, and we can use the first difference to substitute in values for *point sources* that are saturated later in the exposure. This doesn't work for extended sources, so far as we know from our testing to date. The values in Table 2.7 are meant to be single-point values, plain vanilla, with nothing hidden. The values in Table 2.8 are a better approximation to reality, a mixture of point and background sources, subframes that are part of the observing sequence, and the use of some of these subframes to substitute saturated pixels.

How do I best get started with my MIPS data analysis, and how do I make sense of it all?

You can get a quick understanding of the various features in your MIPS data by consulting Chapter 7 in the MIPS Instrument Handbook available at If you're analyzing MIPS-Ge (70 and 160 micron) data and want to maximize your science return, we also encourage you to check out the GeRT: , which allows you to carry out custom offline data reduction. (However, the GeRT should be used carefully; if used improperly, you can corrupt the quality and calibration of your data.) Ultimately, you should familiarize yourself with the entire MIPS Instrument Handbook for further details on MIPS data and analysis.

Why does my MIPS 24+70 photometry observation appear to have no serendipitous 24 micron data?

If the 70 micron data were taken in MIPS-70's fine scale mode, no serendipitous 24 micron data were obtained during the 70 micron observation.  Please see the MIPS Instrument Handbook for more information on dealing with these data.