Background Estimates
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Background Estimates in Sensitivity Plots
Also see:
- IR
Background page from the IR
Compendium - things to worry about when considering backgrounds.
- Spitzer Background
Estimation: Methods and implementation (e.g., how Spot calculates
backgrounds)
The background estimates were generated using a prototype version
of the Spitzer background estimator. Three lines of sight were chosen
to represent low, medium, and high background.
LINE OF SIGHT PARAMETERS
| Galactic | Ecliptic | |||
| glon | glat | elon | elat | |
| low | 96 | +30 | 239 | 89 |
| medium | 105 | -20 | 10 | 40 |
| high | 187 | +1 | 91 | 0 |
BACKGROUND CONTRIBUTIONS
The background model includes the zodiacal light, interstellar medium (cirrus), and the cosmic infrared background (at wavelengths greater than 100 microns). The contributions of each component can be seen in the figure below. The zodiacal light dominates IRAC and IRS wavelengths for all these lines of sight. For MIPS 70 microns, there are comparable interstellar and zodiacal contributions, while at 160 microns, the interstellar contribution dominates.
Figure:
BRIGHTNESS VALUES
The background spectra were integrated over the Spitzer passbands and the results are reported as per the Spitzer calibration convention (same as IRAS, ISO, COBE) below. The first column is the mnemonic wavelength for the band and the second column is the quoted surface brightness of that band. For reference, the color corrections ranged from 0.98 to 1.08.
- A. Low-background
Wavelength
(microns)Background
(MJy/sr)3.60000 0.0769 4.50000 0.267 5.80000 1.37 8.00000 5.47 15.7500 16.8 22.2500 16.7 24.0000 16.1 70.0000 5.15 160.000 6.53 - B. Medium-background
Wavelength
(microns)Background
(MJy/sr)3.60000 0.125 4.50000 0.366 5.80000 1.93 8.00000 7.69 15.7500 24.4 22.2500 24.7 24.0000 23.9 70.0000 8.95 160.000 16.5 - C. High-background
Wavelength
(microns)Background
(MJy/sr)3.60000 0.43 4.50000 0.85 5.80000 4.64 8.00000 18.3 15.7500 63.1 22.2500 67.0 24.0000 65.6 70.0000 32.3 160.000 84.3
Useful Information
- Spitzer Background Estimation: Methods and implementation
- Spitzer Sensitivity Performance Estimator Tool.
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