to major archive collections, we indexed two other instrument archives and surveys:\
[**The Wide Field Imager (WFI) of the Anglo-Australian Telescope (AAT)**]{} was ingested in the [*Mega-Archive*]{} in 2012. We considered important this instrument due to its large etendue, although this archive include only about 5,000 images observed in the period 2000-2006. To manually collect the meta-data we used the former AAT Data Archive form[^14] which was recently integrated in a modern portal serving more instrument archives[^15].

[**The Sloan Digital Sky Survey (SDSS-III DS9 release)**]{} was included in 2013, being queried via the DR9 Science Archive Server[^16]. The [*Mega-Archive*]{} includes almost one million images from the SDSS-III DR9 archive.

Migration to the SQL architecture
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The classic format of the [*Mega-Archive*]{} used between 2010 and 2017 was ASCII (txt files), each observation being stored in one line with columns defining data presented in Section 2.1 (separated by the “” character), and each instrument archive being stored in one file.\
Following the migration to the actual EURONEAR dedicated server, in July 2017 the old [*Mega-Archive*]{} ASCII database was imported to SQL. This change was recommended to keep the search time as short as possible, due to the increase in number of 