Difference between revisions of "Map-making"
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== Zodi correction == | == Zodi correction == | ||
| − | Zodiacal Emission is removed from the 353, 545 and 857 GHz channels. It is described in <span style="color:red">the HFI DPC Paper</span>, but a synopsis of the procedure is as follows: | + | Zodiacal Emission is removed from the 353, 545 and 857 GHz channels. It is described in <span style="color:red">[[XXXXXX|the HFI DPC Paper]]</span>, but a synopsis of the procedure is as follows: |
* During each survey, a large fraction of the sky has observations which all fall within a week of each other. That is, during a single survey, most pixels are observed during a short, well-defined period. The contribution from Zodiacal Emission to the total brightness seen, then, is well defined. | * During each survey, a large fraction of the sky has observations which all fall within a week of each other. That is, during a single survey, most pixels are observed during a short, well-defined period. The contribution from Zodiacal Emission to the total brightness seen, then, is well defined. | ||
* We use the the COBE model of the Zodiacal Light to make predictions for this Zodiacal emission for those pixels observed over a span of one week or less, and use GRASP models of the beams to predict the emission from the Galaxy given our sidelobes. | * We use the the COBE model of the Zodiacal Light to make predictions for this Zodiacal emission for those pixels observed over a span of one week or less, and use GRASP models of the beams to predict the emission from the Galaxy given our sidelobes. | ||
Revision as of 12:10, 18 October 2012
Contents
Introduction
Flux calibration
Noise properties
Zodi correction
Zodiacal Emission is removed from the 353, 545 and 857 GHz channels. It is described in the HFI DPC Paper, but a synopsis of the procedure is as follows:
- During each survey, a large fraction of the sky has observations which all fall within a week of each other. That is, during a single survey, most pixels are observed during a short, well-defined period. The contribution from Zodiacal Emission to the total brightness seen, then, is well defined.
- We use the the COBE model of the Zodiacal Light to make predictions for this Zodiacal emission for those pixels observed over a span of one week or less, and use GRASP models of the beams to predict the emission from the Galaxy given our sidelobes.
- We fit the survey difference maps with these model templates to estimate the emissivity of each Zodi component and sidelobe at the Planck wavelengths.
- We reconstruct each ring of the the full mission using the combination of the COBE geometric model with the emissivities determined above and the sidelobe models.
- We remove the reconstruction above from each ring of data.
- We then make maps as described in section elsewhere in this section.
Far Sidelobe Correction
The far sidelobe correction is described in the section above. Note that this correction is done only for the 857 and 545 GHz channels, as it is not seen at longer wavelengths.
