Observer's guide
About NGC 6121
NGC 6121 (M4) is catalogued as a globular cluster in Scorpius. Its J2000 position is RA 16:23:35.40, Dec -26:31:31.9, corresponding to 245.8968 degrees RA and -26.5258 degrees Dec. The local catalogue places it about 7,200 light-years away. Its referenced angular extent is approximately 26.3 by 26.3 arcminutes.
Observing tips
StarWatchr rates this as a hard target at magnitude 5.6. It is associated with summer observing, with midnight placement typically strongest around May. From 52 degrees north its theoretical meridian altitude is about 11.5 degrees; local horizons and the live altitude chart determine the practical window.
Its brightness makes it a practical binocular or small-telescope candidate when it is well above the horizon.
What to expect
The SIMBAD classification for the matched source is GlC. A published radial velocity value is 71 km/s. The SIMBAD record currently connects it to 1996 bibliographic references.
Its roughly 26.3 arcminute span suits a medium field of view. Use the listed 26.3 by 26.3 arcminute extent to check framing, and treat catalogue magnitude as integrated brightness rather than a direct measure of visual contrast.