۱- Introduction

۲- Mega-Archive

۳- Data mining tools

۴- Use case scenarios

۵- Comparison with other services

۶- Conclusions and recommendations

References

Abstract

The world astronomical image archives offer huge opportunities to time-domain astronomy sciences and other hot topics such as space defense, and astronomical observatories should improve this wealth and make it more accessible in the big data era. In 2010 we introduced the Mega-Archive database and the Mega-Precovery server for data mining images serendipitously containing Solar system bodies, with focus on near Earth asteroids (NEAs). This paper presents the improvements and introduces some new related data mining tools developed during the last years. Currently, Mega-Archive indexed 15 million images available from six major collections and other instrument archives and surveys. This meta-data index collection is daily updated by a crawler which performs automated query of five major collections. Since 2016, these data mining tools are installed on the new dedicated EURONEAR server, and the database migrated to SQL which supports robust and fast queries. To constrain the area to search for moving or fixed objects in images taken by large mosaic cameras, we built the graphical tools FindCCD and FindCCD for Fixed Objects which overlay the targets across one of seven mosaic cameras, plotting the uncertainty ellipse for poorly observed NEAs. In 2017 we improved Mega-Precovery, which offers now two options for the ephemerides and three options for the input (objects defined by designation, orbit or observations). Additionally, we developed Mega-Archive for Fixed Objects (MASFO) and Mega-Archive Search for Double Stars (MASDS). We include a few use case scenarios and we compare our data mining tools with other few similar services. The huge potential of science imaging archives is still insufficiently exploited. Their use could be strongly enhanced by defining a standard format needed to index the image archives. We recommend to the IAU to define such a standard, asking the observatories to index their image archives in a homogeneous manner.

Introduction

The world astronomical image archives provide valuable means to improve the physical properties of Solar System bodies, and in particular of near Earth asteroids (NEAs) which typically remain observable only for short period of times. NEAs represent laboratories for studying the formation and evolution of the minor planets and their physical interactions with the Sun and major planets. Part of NEAs, potentially hazardous asteroids (PHAs) and virtual impactors (VIs) could pose some risk due to their possibility of impact, but they also represent an opportunity for more accessible space missions and eventually future mining industries. Upon discovery, the recovery and follow-up of NEAs are essential for providing the initial orbital solution and for searching of possible linkage with previously known objects. In most cases, smaller NEAs fade rapidly and become invisible even for largest telescopes which are expensive to access and usually lack time for urgent reaction. However, the existing image archives represent a free opportunity to improve the orbital knowledge based on serendipitous encounters of targets searched using dedicated data mining tools. Searching for fixed objects (like stars or galaxies) in image archives is straightforward, because only the position of the target is needed to compare with the known telescope pointing and instrument field. The largest astronomical observatories or their collaborating institutions provide simple web searching tools or more sophisticated services which allow searches of fixed objects only in their image archives.