J. Gwyn and colleagues [@Gwyn2012a; @Gwyn2012b], being focused first only on the CADC archive and enhanced later with many other archives [@Gwyn2014; @Gwyn2015a; @Gwyn2015b; @Gwyn2016]. Another similar project to search for moving objects in image archives was “The Planetary Archive”, which was announced in 2014 [@Penteado2014] but whose outcome is unknown.

Mega-Archive
============

The largest astronomical observatories and related data centres provide [*science archive collections*]{} taken by their instruments and telescopes. These archives are served by common user interfaces allowing anybody to search and download images, spectra, catalogs and other data products. Following our first EURONEAR [*Precovery*]{} projects [@Vaduvescu2009; @Vaduvescu2011; @Vaduvescu2013], in 2010 we joined the first three [*instrument archives*]{} (CFHTLS, ESO/MPG and ING/INT) to start building the [*Mega-Archive*]{} database [@Popescu2010], with the aim to index at least one million images and add more archives later.

Archive Format and Index
------------------------

To search for any fixed or moving objects, any archive collection must contain some basic information about the observed images. To index the instrument archives within our database, the following “meta-data” fields are essential to be included:\

[**Image ID**]{} - *the string needed for downloading the FITS image file*

[**Observing date and time**]{} - *start of exposure in JD 