thank you for reaching out. In case the question is still current:
- Prepare your table as a CSV file, with a single-line header, followed by N rows of positions you want to cross-match. Among the columns, ra and dec MUST be present (but can be named something else, e.g. ra2000, etc). You can have any number of other columns, and the column order does not matter. An example:
$head -1 myfile.csv
- In the cross-match web-form https://datalab.noao.edu/xmatch.php
(log in first, if you aren't yet), click on the "Table management" tab, and upload your CSV file.
- Switch back to the "Xmatch" tab, and select your freshly uploaded table as the first table. You will have to tell it also what are the actual ra and dec columns. Then select the other table to cross-match, the matching options, and result delivery options, and hit "Submit".