10. Large-Area Mapping in the Trapezium at 3.6 - 8.0 microns with IRAC

In the previous chapter, we described the procedure to develop a large-area imaging campaign using MIPS. In this chapter, we develop a complementary project to image the same regions of the sky in the 3.6 - 8.0 micron range using IRAC. A brief note before we get started: in §4 we designed an IRAC deep imaging campaign. Many of the details of setting up the observations, and the Spot interface, are similar between the example expanded in this chapter, and the deep imaging observation in §4. Therefore, we have provided somewhat less detail here, and refer to §4 for further information. IRAC's images are at $3.6$, $4.5$, $5.8$, and $8.0 \; \mu {\rm m}$, with bandwidths of $0.7$, $1.0$, $1.4$, and $2.9 \; \mu {\rm m}$, respectively. Each pixel is $\sim1\hbox{$.\!\!^{\prime\prime}$}2$; each image covers a total of $\sim 5\hbox{$.\!\!^{\prime}$}2 \times 5\hbox{$.\!\!^{\prime}$}2$. Recall that $3.6$ and $5.8 \; \mu {\rm m}$ share an entrance aperture, as do $4.5$ and $8.0 \; \mu {\rm m}$. We want to cover an area comparable to the MIPS survey above (see §9) but still be able to reject cosmic rays, so we'll need to dither, with at least 3 images per patch of sky.