Hello, Christophe.
In fact, VSX and Simbad cannot guarantee whether something is unknown or not. We should also check Vizier (VizieR). Once you open the page, you can enter the coordinates in the lower left corner, select the appropriate Target dimension parameter, and then click “Go”.
Additionally, the FAQ and Guidelines on the VSX page can help you with some of your questions.
In fact, ATO entries need to be carefully reviewed. If they are labeled as “dubious,” feel free to boldly list yourself as the discoverer.
If Gaia or others have misclassified an object (such as classifying an EA as an S or an EA+BY as an RR), you can list yourself as a co-discoverer.
If a variable star is included in the Pan-STARRS1 RR Lyrae candidates in 2017AJ…153…204S and listed with an incorrect classification, you can add yourself as a co-discoverer (by the way, 2017AJ…153…204S has many problematic entries, making it an ideal place to search for new variable stars).
If the variable star is listed in The ZTF catalog of periodic variable stars (Chen+, 2020) - ZTF suspected variables catalog (Vizier:J/ApJS/249/18/table3), then it is also unknown.
If the variable star does not exist in any variable star catalog (such as Gaia, ATLAS, CSS, VSX, ZTF…), congratulations, it is likely an unknown variable star.
However, it is obvious that there are many related Vizier entries. When reviewing them, we need to carefully determine their meanings.
I hope this can help you.
Best regards,
Jiashuo Zhang