Observer's guide
About Ptolemy's Cluster
Ptolemy's Cluster (M7) is catalogued as an open cluster in Scorpius. Its J2000 position is RA 17:53:51.18, Dec -34:47:34.2, corresponding to 268.4471 degrees RA and -34.8411 degrees Dec. The local catalogue places it about 800 light-years away. Its referenced angular extent is approximately 100.1 by 100.1 arcminutes.
Observing tips
This is rated as an easy target at magnitude 4.1. It is associated with summer observing, with midnight placement typically strongest around June. From 52 degrees north its theoretical meridian altitude is about 3.2 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 OpC. A published radial velocity value is -14.7 km/s. The SIMBAD record currently connects it to 419 bibliographic references.
At roughly 100.1 arcminutes across, it favors a wide-field imaging setup. Use the listed 100.1 by 100.1 arcminute extent to check framing, and treat catalogue magnitude as integrated brightness rather than a direct measure of visual contrast.