Observer's guide
About NGC 6218
NGC 6218 (M12) is catalogued as a globular cluster in Ophiucus. Its J2000 position is RA 16:47:14.52, Dec -01:56:52.2, corresponding to 251.8091 degrees RA and -1.9485 degrees Dec. The local catalogue places it about 16,000 light-years away. Its referenced angular extent is approximately 14.5 by 14.5 arcminutes.
Observing tips
This is rated as a moderate target at magnitude 6.7. It is associated with summer observing, with midnight placement typically strongest around May. From 52 degrees north its theoretical meridian altitude is about 36.1 degrees; local horizons and the live altitude chart determine the practical window.
A small telescope under reasonably dark skies is a good starting point; use the live altitude chart to choose its highest point.
What to expect
The SIMBAD classification for the matched source is GlC. A published radial velocity value is -41.2 km/s. The SIMBAD record currently connects it to 744 bibliographic references.
At roughly 14.5 arcminutes across, it benefits from a narrower field and adequate image scale. Use the listed 14.5 by 14.5 arcminute extent to check framing, and treat catalogue magnitude as integrated brightness rather than a direct measure of visual contrast.