Observer's guide
About NGC 6864
NGC 6864 (M75) is catalogued as a globular cluster in Sagittarius. Its J2000 position is RA 20:06:04.84, Dec -21:55:20.0, corresponding to 301.5202 degrees RA and -21.9223 degrees Dec. The local catalogue places it about 57,700 light-years away. Its referenced angular extent is approximately 2.38 by 2.15 arcminutes.
Observing tips
StarWatchr rates this as a moderate target at magnitude 8.5. It is associated with summer observing, with midnight placement typically strongest around July. From 52 degrees north its theoretical meridian altitude is about 16.1 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 -188.6 km/s. The SIMBAD record currently connects it to 396 bibliographic references.
At roughly 2.4 arcminutes across, it benefits from a narrower field and adequate image scale. Use the listed 2.38 by 2.15 arcminute extent to check framing, and treat catalogue magnitude as integrated brightness rather than a direct measure of visual contrast.