Difference between revisions of "Catalogues"
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The Mexican Hat Wavelet 2 (MHW2; Gonzalez-Nuevo et al., 2006) is the base algorithm used to produce the single channel catalogues of the PCCS. Although each DPC has is own implementation of this algorithm (IFCAMEX and HFI-MHW), the results are compatible at least at the statistical uncertainty level. Additional algorithms are also implemented, like the multi-frequency Matrix Multi-filters (MTXF; Herranz et al., 2009) and the Bayesian PowellSnake (Carvalho et al. 2009), but for the current version of the PCCS they are used just for the validation of the results obtained by the MHW2. | The Mexican Hat Wavelet 2 (MHW2; Gonzalez-Nuevo et al., 2006) is the base algorithm used to produce the single channel catalogues of the PCCS. Although each DPC has is own implementation of this algorithm (IFCAMEX and HFI-MHW), the results are compatible at least at the statistical uncertainty level. Additional algorithms are also implemented, like the multi-frequency Matrix Multi-filters (MTXF; Herranz et al., 2009) and the Bayesian PowellSnake (Carvalho et al. 2009), but for the current version of the PCCS they are used just for the validation of the results obtained by the MHW2. | ||
− | The full-sky maps are divided into a sufficient number of overlapping flat patches in such a way that 100% of the sky is covered. Each patch is then filtered by the MHW2 with a scale that is optimised to provide the maximum signal-to-noise ratio in the filtered maps. A sub-catalogue of objects is produced for each patch and then, at the end of the process, all the sub-catalogues are merged together, removing repetitions. For each channel a parent sample is created containing all the sources detected with a signal-to-noise greater than 4. These 9 lists, that contain the positions, native flux densities and errors, are used as inputs in the validation step. The results of the validation process are finally used to decided the final thresholding or removal of spurious sources. | + | The full-sky maps are divided into a sufficient number of overlapping flat patches in such a way that 100% of the sky is covered. Each patch is then filtered by the MHW2 with a scale that is optimised to provide the maximum signal-to-noise ratio in the filtered maps. A sub-catalogue of objects is produced for each patch and then, at the end of the process, all the sub-catalogues are merged together, removing repetitions. For each channel, a parent sample is created containing all the sources detected with a signal-to-noise greater than 4. These 9 lists, that contain the positions, native flux densities and errors, are used as inputs in the validation step. The results of the validation process are finally used to decided the final thresholding or removal of spurious sources. |
=== Photometries === | === Photometries === | ||
+ | In addition of the native flux density estimation provided by the detection algorithm, three additional measurements are obtained for each of the source in the parent samples. | ||
+ | These additional flux density estimations are based on aperture photometry, PSF fitting and Gaussian fitting. The native flux density estimation is the only one that is obtained directly from the filtered maps while for the others the flux density estimates has a local background subtracted. The flux density estimations have not been colour corrected. Colour corrections are available in <span style="color:red">[reference to the Color Correction description or Planck Cosmology and Product Paper 05a]</span>. | ||
=== Validation process === | === Validation process === |
Revision as of 15:50, 19 October 2012
Contents
Planck Catalogue of Compact Sources[edit]
The Planck Catalogue of Compact Sources (PCCS) is a sample of reliable sources, both Galactic and extragalactic, extracted directly from the Planck nominal maps. The first public version of the PCCS is derived from the data acquired by Planck between August 13 2009 and November 26 2010. The PCCS consists of nine lists of sources, extracted independently from each of Planck's nine frequency channels. It is fully described in [reference to the Planck Cosmology and Product Paper 05a].
The whole PCCS can be downloaded here [1].
Detection procedure[edit]
The Mexican Hat Wavelet 2 (MHW2; Gonzalez-Nuevo et al., 2006) is the base algorithm used to produce the single channel catalogues of the PCCS. Although each DPC has is own implementation of this algorithm (IFCAMEX and HFI-MHW), the results are compatible at least at the statistical uncertainty level. Additional algorithms are also implemented, like the multi-frequency Matrix Multi-filters (MTXF; Herranz et al., 2009) and the Bayesian PowellSnake (Carvalho et al. 2009), but for the current version of the PCCS they are used just for the validation of the results obtained by the MHW2.
The full-sky maps are divided into a sufficient number of overlapping flat patches in such a way that 100% of the sky is covered. Each patch is then filtered by the MHW2 with a scale that is optimised to provide the maximum signal-to-noise ratio in the filtered maps. A sub-catalogue of objects is produced for each patch and then, at the end of the process, all the sub-catalogues are merged together, removing repetitions. For each channel, a parent sample is created containing all the sources detected with a signal-to-noise greater than 4. These 9 lists, that contain the positions, native flux densities and errors, are used as inputs in the validation step. The results of the validation process are finally used to decided the final thresholding or removal of spurious sources.
Photometries[edit]
In addition of the native flux density estimation provided by the detection algorithm, three additional measurements are obtained for each of the source in the parent samples. These additional flux density estimations are based on aperture photometry, PSF fitting and Gaussian fitting. The native flux density estimation is the only one that is obtained directly from the filtered maps while for the others the flux density estimates has a local background subtracted. The flux density estimations have not been colour corrected. Colour corrections are available in [reference to the Color Correction description or Planck Cosmology and Product Paper 05a].
Validation process[edit]
Internal validation[edit]
External validation[edit]
Planck SZ Cluster Catalogue[edit]
The Planck SZ Cluster Catalogue is a nearly full-sky list of highly-reliable SZ clusters detected in the Planck data. It is fully described in [reference to the Planck Cosmology and Product Paper 05a]. The catalogue is derived from the HFI frequency channel maps after masking and filling the bright point sources (SNR >= 10) from the general PCCS catalogue in those channels. Three detection methods were used to construct the catalogue: two implementations of the Matched Multi-Filter (MMF) algorithm and PowellSnakes (PwS), a Bayesian algorithm. A Galactic dust mask (leaving 85% of the sky) and a point source mask is applied a posteriori to remove detections in the portion of the sky where foregrounds are likely to cause spurious detections.
The master catalogue contains the merger of the catalogues from the three detection methods. The individual catalogues are also provided for the expert user in order to assess the consistency of the methods. The completeness and reliability of the catalogues have been assessed through internal and external validation. The catalogue has a reliability of 85% (TBC).
Early Release Compact Source Catalogue[edit]
The ERCSC is a list of high reliability (>90%) sources, both Galactic and extragalactic, derived from the data acquired by Planck between August 13 2009 and June 6 2010. The ERCSC consists of:
- nine lists of sources, extracted independently from each of Planck's nine frequency channels
- two lists extracted using multi-channel criteria: the Early Cold Cores catalogue (ECC), consisting of Galactic dense and cold cores, selected mainly on the basis of their temperature ; and the Early Sunyaev-Zeldovich catalogue (ESZ), consisting of galaxy clusters selected by the spectral signature of the Sunyaev-Zeldovich effect.
The whole ERCSC can be downloaded here [2].
The ERCSC is also accessible via the NASA/IPAC Infrared Science Archive [3].
Data Processing Center
(Planck) High Frequency Instrument
Sunyaev-Zel'dovich
To be confirmed
Early Release Compact Source Catalog