Observatory Overview

The Observational Capabilities of Spitzer

Spitzer Imaging Measurement Functionality:

Spitzer imaging benefits from wide-field, large-format arrays. This chart shows the pixel sizes of each Spitzer imaging array and the effective fields of view. IRS imaging is accomplished through the use of the 15 micron peak-up array. Mapping of large fields is done using a step-and-stare method with IRAC. MIPS provides mapping through the use of a cryogenic scan mirror.

Also see this plot for an overview of common SEDs and Spitzer sensitivity.

Spitzer Spectroscopic Measurement Functionality:

Spitzer's spectroscopic capabilities are primarily supported by IRS, and through the MIPS Spectral Energy Distribution (SED) Mode. This chart shows the resolving power as a function of wavelength for the three Spitzer instruments. Those with resolving powers of less than 10 are primarily broadband imaging instruments.

Spitzer Instrumentation Summary:

[1] Sensitivities given here are for point sources and are only representative. See Chapters 6-8 in the Spitzer Observer's Manual and the instrument web pages for more detail.
[2] IRAC sensitivity is given for intermediate background. The first number in each case is without confusion, and the second number (in parentheses) includes confusion.
[3] IRS sensitivity is given for low background at high ecliptic latitude. Note that for IRS, sensitivity is a strong function of wavelength.
[4] For recommended flux density range for peak-up target, please refer to Spitzer Observer's Manual, Chapter 7.
[5] MIPS sensitivity is given for low background.
[6] 70 um can be confusion limited; see SOM for more details.
[7] Because of a bad readout at one end of the slit, the spectral coverage for 4 columns of the array is reduced to about 65-95 microns.
[8] 160 um is often confusion limited; the first number is without confusion and the second number (in parentheses) includes confusion.

The Spitzer Focal Plane:

This figure shows schematically how the science instrument apertures are projected onto the sky. Because of the optical inversion in this projection, the section of sky closest to the projected Sun is on the MIPS side of the focal plane, e.g. to the right in this view. Because the spacecraft does not rotate about the line of sight, this vector is fixed relative to the focal plane on the sky. The IRAC sub-array fields are shown by the small boxes in the lower corners of both IRAC arrays. (The 8.0 and 5.8 micron sub-arrays are on the right and the 4.5 and 3.6 micron sub-arrays are on the left.) Note that the widths of the IRS slits are substantially larger than their actual scale.