Abstract
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.
Highlights
Providing the Solar System research community with swift and easy access to the astronomical data archives is a long-standing issue
The full list of all potential detection candidates from the System Object Search Service (SSOSS) is publicly available via the ESASky table access protocol (TAP) server18, which can be accessed in a variety of ways, for instance, from the VO tool TOPCAT and from the astroquery TAP module (Ginsburg et al 2019)
We analyze these results for the asteroid population and describe the different estimations applied to compute the limiting magnitude or flux sensitivity for each of the instruments included in this work to produce a final catalogue of asteroid serendipitous detections above the instrument’s sensitivity
Summary
Providing the Solar System research community with swift and easy access to the astronomical data archives is a long-standing issue. Moving targets seen at different sky positions and under very different observing geometries are not easy to aggregate within a single tool. Multi-epoch observations over several oppositions are required to compute the orbit to a sufficient level of accuracy required for targeted studies. The archived imaging data contains both serendipitous and targeted observations of asteroids, where, in particular, the astrometry of the former can greatly reduce these ephemerides uncertainties at visible wavelengths when harvested (e.g., precovery of near-Earth asteroids Solano et al 2014). The extracted photometry can be used to constrain the phase function and, if multi-band observations were acquired within a short period of time, they can even allow for a color determination and rudimentary taxonomic classification of the asteroid (DeMeo & Carry 2013; Shevchenko et al 2016)
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