ESASky SSOSS: Solar System Object Search Service and the case of Psyche

Description

Context. The store of data collected in public astronomical archives across the world is continuously expanding and, thus, providing a convenient interface for accessing this information is a major concern for ensuring a second life for the data. In this context, Solar System objects (SSOs) are often difficult or even impossible to query, owing to their ever-changing sky coordinates.
Aims: Our study is aimed at providing the scientific community with a search service for all potential detections of SSOs among the ESA astronomy archival imaging data, called the Solar System Object Search Service (SSOSS). We illustrate its functionalities using the case of asteroid (16) Psyche, for which no information in the far-IR (70-500 μm) has previously been reported, to derive its thermal properties in preparation for the upcoming NASA Psyche mission.
Methods: We performed a geometrical cross-match of the orbital path of each object, as seen by the satellite reference frame, with respect to the public high-level imaging footprints stored in the ESA archives. There are about 800 000 asteroids and 2000 comets included in the SSOSS, available through ESASky, providing both targeted and serendipitous observations. For this first release, three missions were chosen: XMM-Newton, the Hubble Space Telescope (HST), and Herschel.
Results: We present a catalog listing all potential detections of asteroids within estimated limiting magnitude or flux limit in Herschel, XMM-Newton, and HST archival imaging data, including 909 serendipitous detections in Herschel images, 985 in XMM-Newton Optical Monitor camera images, and over 32 000 potential serendipitous detections in HST images. We also present a case study: the analysis of the thermal properties of Psyche from four serendipitous Herschel detections, combined with previously published thermal IR measurements. We see strong evidence for an unusual drop in (hemispherical spectral) emissivity, from 0.9 at 100 μm down to about 0.6 at 350 μm, followed by a possible but not well-constrained increase towards 500 μm, comparable to what was found for Vesta. The combined thermal data set puts a strong constraint on Psyche's thermal inertia (between 20 to 80 J m⁻² s^−1/2 K⁻¹) and favors an intermediate to low level surface roughness (below 0.4 for the rms of surface slopes).
Conclusions: Using the example of Psyche, we show how the SSOSS provides fast access to observations of SSOs from the ESA astronomical archives, regardless of whether the particular object was the actual target. This greatly simplifies the task of searching, identifying and retrieving such data for scientific analysis.

The catalog is also available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/659/A38

Abstract

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