other existing search options being left as default):

[**Las Cumbres Observatory Global Telescope (LCOGT)**]{} provides since 2013 their Science Archive [@Lister2013], storing all the images taken with the instruments and telescopes of this network. In 2017 we collected 21 available imagers from all telescopes, treating each instrument mounted on any telescope as one distinct archive (due to the distinct locations and MPC codes of each telescope). Today [*Mega-Archive*]{} includes more than one million images from the LCOGT collection. The LCOGT Science Archive[^10] could be manually or programatically queried based on the following options:

[**The Isaac Newton Group (ING)**]{} built in 2014 the ING science data archive based on telescope observing logs. We used this facility to ingest in the [*Mega-Archive*]{} almost 1.5 million images taken with 8 instruments mounted at all 3 ING telescopes. Besides the night observing logs, the ING query form[^11] allows an “Advanced search and browse” section for retrieval of meta-data and links to the available ING images sorted based on a few constraints. We used the following parameters to search all available ING images (all other available search options on this form being left as default):

[**The U.S. National Optical Astronomical Observatory (NOAO)**]{} provides since 2007 