The Planck Catalogue of Galactic Cold Clumps (PGCC) is a list of 13188 Galactic sources and 54 sources
located in the Small and Large Magellanic Clouds, identified as cold sources in Planck data, as described in
Planck-2015-A28[20]. The sources are extracted with the CoCoCoDeT algorithm (Montier, 2010), using
Planck-HFI 857-, 545-, and 353-GHz maps and the 3-THz IRIS map (Miville 2005), an upgraded version of the
IRAS data at 5 arcmin resolution. This is the first all-sky catalogue of Galactic cold sources obtained with
homogeneous methods and data. The CoCoCoDeT detection algorithm uses the 3-THz map as a spatial template of
a warm background component. Local estimates of the average colour of the background are derived at 30
arcmin resolution around each pixel of the maps at 857, 545, and 353 GHz. Together these describe a local
warm component that is subtracted, leaving 857-, 545-, and 353-GHz maps of the cold residual component map
over the full sky. A point source detection algorithm is then applied to these three maps. A detection
requires S/N > 4 in pixels in all Planck bands and a minimum angular distance of 5 arcmin from other
detections. A 2D Gaussian fit provides an estimate of the position angle and FWHM size along the major and
minor axes. The ellipse defined by the FWHM values is used in aperture photometry to derive the flux density
estimates in all four bands. Based on the quality of the flux density estimates in all four bands, PGCC
sources are divided into three categories of FLUX_QUALITY: FLUX_QUALITY=1, sources with flux density
estimates at S/N > 1 in all bands ; FLUX_QUALITY=2, sources with flux density estimates at S/N > 1 only in
857-, 545-, and 353-GHz Planck bands, considered as very cold source candidates ; FLUX_QUALITY=3, sources
without any reliable flux density estimates, listed as poor candidates. We also set a flag for the blending
between sources, which can be used to ...quantify the reliability of the aperture photometry processing. To estimate possible contamination by extragalactic sources we: (1) cross-correlated the positions with catalogues of extragalactic sources; (2) rejected detections with SED (in colour-colour plots) consistent with radio sources; and (3) rejected detections with clear association with extragalactic sources visible in Digitized Sky Survey images. Compared to the original catalogue, these only resulted in a small number of rejections. More information: https://wiki.cosmos.esa.int/planck-legacy-archive/index.php/Catalogues
Instrument
LFI and HFI
Temporal Coverage
2009-08-12/2013-10-23
Version
PR2
Mission Description
Planck is ESA's mission to observe the first light in the Universe. Planck was selected in 1995 as the third
Medium-Sized Mission (M3) of ESA's Horizon 2000 Scientific Programme, and later became part of its Cosmic
Vision Programme. It was designed to image the temperature and polarization anisotropies of the Cosmic
Background Radiation Field over the whole sky, with unprecedented sensitivity and angular resolution. Planck
is testing theories of the early universe and the origin of cosmic structure and providing a major source of
information relevant to many cosmological and astrophysical issues.
