Observer's guide
About Tau Canis Majoris Cluster
Tau Canis Majoris Cluster (C64) is catalogued as an open cluster in Canis Major. Its J2000 position is RA 07:18:42, Dec -24:57:15, corresponding to 109.6708 degrees RA and -24.9539 degrees Dec. The local catalogue places it about 5,100 light-years away. Its referenced angular extent is approximately 104 by 104 arcminutes.
Observing tips
This is rated as a very easy target at magnitude 4.1. It is associated with winter observing, with midnight placement typically strongest around January. From 52 degrees north its theoretical meridian altitude is about 13 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 37.5 km/s. The SIMBAD record currently connects it to 434 bibliographic references.
At roughly 104 arcminutes across, it favors a wide-field imaging setup. Use the listed 104 by 104 arcminute extent to check framing, and treat catalogue magnitude as integrated brightness rather than a direct measure of visual contrast.