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HerMES Team makes Maps and Catalogues Public


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On April 3rd, 2012, the HerMES team announced a major data release (referred to as DR1. The release includes Herschel SPIRE sky maps and object catalogues containing more than 17,000 galaxies that have been reliably detected by the SPIRE instrument on the Herschel satellite.

 

 

Bootes DR1The maps were made using 250, 350 and 500 micrometer filters on Herschel's SPIRE instrument. These sub-milimeter wavelengths had not been significantly exploited before the Herschel Mission. The maps cover ~74 square degrees of the sky, which corresponds to a volume of 660 million cubic Mega parsecs (1 Mega parsec is 3.26 million light years) for redshifts z<1.5 (and many of the galaxies that we see are expected to be at z>1.5). This can be compared to the giant Sloan survey that mapped a much larger area of around a quarter of the sky but to much shallower depths (redshifts z<0.17) encompassing a similar volume of 350 million cubic Megaparsecs. The volumes are comparable which means the HerMES maps are much much deeper than the Sloan survey. HerMES are releasing data in many very well studied extragalactic survey fields and so we expect this will facilitate a huge range of astrophysics and cosmology.

The maps range in depth but are mostly at or below the SPIRE confusion limit where individual galaxies are so numerous they they become difficult to distinguish and so provide the very best quality view of the sub-millimeter sky, limited primarily only by the diameter of the Herschel mirror.

 

The image above shows one of the fields released, the Bootes field, located in the Northern hemisphere in the constellation of the same name.

 

 

The catalogues extracted from these maps include over 50, 000 catalogue entries, representing over 17, 000 galaxies. For such large, deep surveys, reliability (whether a detection is true or fake) can be a real problem. For the HerMES catalogues, extensive simulations have demonstrated that these catalogues are very high quality and ~90% of the point-like galaxies having very reliable positions and brightness measurements.

This data release follows two early data releases (July 2010 and September 2011) which were limited to the brightest catalogued sources over a smaller range of fields. 

 

 

The data is explained in detail in the scientific paper

Oliver, S et al., MNRAS 2012 in press, arXiv:1203.2562

All data is available through the Herschel database HeDaM