Today it manages data collections taken with many other North American telescopes. Since the beginning of our project we ingested some of the CFHT archives. Currently, the [*Mega-Archive*]{} includes about two million images from 29 instruments (visible and NIR) installed on 8 telescopes linked to the CADC collection. The CADC Advanced Search[^8] allows multiple archive selections using a CGI form which presents a few selection menus. The CADC archive also allows programmatic queries, and for each instrument we used the following options to retrieve the needed meta-data for all available optical and NIR images (all other search options being left as default):

[**The European Southern Observatory (ESO)**]{} started in 1994 to archive NTT images [@Albrecht1994], and provides today one of the largest collection taken with major ESO telescopes in La Silla and Paranal. The [*Mega-Archive*]{} includes more than 3.3 million images from 15 instruments installed on 9 ESO telescopes. In order to query the ESO archive, we used the [*ESO Science Archive Facility*]{}[^9]. It allows to search and retrieve Raw Data using a CGI form showing two main selection blocks about the target/program and observing information. For each instrument we used the following options to search all available images (all 