HerMES: point source catalogues from deep Herschel-SPIRE observations

TL;DR

This paper details the creation of point source catalogues from Herschel-SPIRE submillimetre observations, including methods for flux measurement, completeness assessment, and accuracy validation, serving as a reference for the HerMES data release.

Contribution

It introduces a methodology for generating and validating point source catalogues from Herschel-SPIRE data, emphasizing completeness and flux accuracy checks using artificial source injection.

Findings

Flux density thresholds for 50% detection completeness at different wavelengths.

Effective methods for source detection and flux measurement in confused images.

Validation of catalogue accuracy through artificial source injection.

Abstract

We describe the generation of single-band point source catalogues from submillimetre Herschel-SPIRE observations taken as part of the Science Demonstration Phase of the Herschel Multi-tiered Extragalactic Survey (HerMES). Flux densities are found by means of peak-finding and the fitting of a Gaussian point-response function. With highly-confused images, careful checks must be made on the completeness and flux density accuracy of the detected sources. This is done by injecting artificial sources into the images and analysing the resulting catalogues. Measured flux densities at which 50 per cent of injected sources result in good detections at (250, 350, 500) {\mu}m range from (11.6, 13.2, 13.1) mJy to (25.7, 27.1, 35.8) mJy, depending on the depth of the observation (where a `good' detection is taken to be one with positional offset less than one full-width half-maximum of the point-response function, and with the measured flux density within a factor of 2 of the flux density of the injected source). This paper acts as a reference for the 2010 July HerMES public data release.