IR Compendium: Background: Resolution
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This is the page on Resolution; also see Diffraction, Confusion, and (IR) Background
Resolution (Jump to Spitzer-specific section)
When comparing images at different wavelengths, check that the spatial resolution is comparable! This matters, particularly for mid- and far-IR observations (see 'diffraction' below).
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| Original visible light image of M33. | The same visible light image, smoothed to a resolution typical of far-IR observations. | Especially in IR images, intensities are often translated to colors ("false color"). Image colors are often selected to emphasize different details than are discernable in a black-and-white image. |
Here is a table comparing pixel sizes and resolutions of several different instruments; see also the plot below:
| Instrument/Data Set | Wavelength(s) (microns) | Pixel Size (arcsec) | Resolution (arcsec) | Array Field of View | Reference |
|---|---|---|---|---|---|
| DSS/POSS-I | 0.4, 0.65 | 1.7 | typically ˜2 | 6.5° x 6.5° | MAST DSS FAQ, Skyview survey summaries |
| DSS/POSS-II | 0.45, 0.65, 0.8 | 1.0 | typically better than 2 | 6.5° x 6.5° | MAST DSS FAQ, Skyview survey summaries |
| 2MASS | 1.25, 1.65, 2.17 | ˜2.0 | 1 | 8.5' x 8.5' | 2MASS Explanatory Supplement, Skyview survey summaries |
| ISO-CAM SW5 | 4.0 | 1.5 | ˜ 1.66 | 45" x 45" | ISO Handbook, Version 1.2, ISO PSF Report (Okumura, 1998) |
| ISO-CAM LW1 | 4.5 | 1.5 | ˜ 2.30 | 45" x 45" | ISO Handbook, Version 1.2, ISO PSF Report (Okumura, 1998) |
| ISO-CAM LW5 | 6.8 | 1.5 | ˜ 2.40 | 45" x 45" | ISO Handbook, Version 1.2, ISO PSF Report (Okumura, 1998) |
| ISO-CAM LW7 | 9.6 | 1.5 | ˜ 3.19 | 45" x 45" | ISO Handbook, Version 1.2, ISO PSF Report (Okumura, 1998) |
| ISO-CAM LW10 | 12 | 1.5 | ˜ 3.70 | 45" x 45" | ISO Handbook, Version 1.2, ISO PSF Report (Okumura, 1998) |
| ISO-CAM LW9 | 14.9 | 1.5 | ˜ 5.11 | 45" x 45" | ISO Handbook, Version 1.2, ISO PSF Report (Okumura, 1998) |
| IRAS | 12 | 30 | ˜20 | 4.45' x 0.76' | IRAS Explanatory Supplement, Skyview survey summaries |
| IRAS | 25 | 30 | ˜20 | 4.65' x 0.76' | IRAS Explanatory Supplement, Skyview survey summaries |
| IRAS | 60 | 60 | ˜60 | 4.75' x 1.51' | IRAS Explanatory Supplement, Skyview survey summaries |
| ISO-PHT C70 | 80 | 43.5 | ˜ 59.0 | 2.3' x 2.3' | ISO Handbook Volume 2.0 |
| IRAS | 100 | 120 | ˜120 | 5.05' x 3.03' | IRAS Explanatory Supplement, Skyview survey summaries |
| ISO-PHT C160 | 170 | 89.4 | ˜ 134.0 | 3.0' x 3.0' | ISO Handbook Volume 2.0 |
Resolution and Spitzer
Spitzer's resolution is a strong function of wavelength; see this overview page.Also see the simulations on the page on confusion noise.
The following plot comes from the SOFIA
website.
Part of this page was adapted from Marcia Rieke's talk at the Seattle AAS, January 2003
