Deep Herschel PACS point spread functions

TL;DR

This paper presents highly detailed point spread functions (PSFs) for the Herschel PACS instrument, combining observations of Vesta and Mars to achieve unprecedented dynamic range across different scan speeds and bands.

Contribution

It introduces a new method to derive comprehensive PSFs with a dynamic range of about one million, improving the characterization of both core and wings of the PSF.

Findings

PSFs with dynamic range ~10^6 across all bands

Enhanced understanding of PSF core and wings

Applicable to various scan speeds

Abstract

The knowledge of the point spread function (PSF) of imaging instruments represents a fundamental requirement for astronomical observations. The Herschel PACS PSFs delivered by the instrument control centre are obtained from observations of the Vesta asteroid, providing a characterisation of the central part therefore excluding fainter features. However, in many cases information on both the core and the wings of the PSFs is needed. With this aim, we combine Vesta and Mars dedicated observations and obtain PACS PSFs with an unprecedented dynamic range $(\sim 10^6)$, at slow and fast scan speeds and for the three photometric bands.