41 is a open cluster lying at the heart of the constellation of
Canis Major, the larger of Orion's two hunting dogs. It is relatively
large in appearance, spanning 38 arcminutes (slightly larger than
the width of a full moon). It lies 2300 light years away and has
an actual diameter of 25 light years. It contains approximately
100 stars, including some red giants.
a visual magnitude is 4.5, it is visible to the naked eye under
dark skies. It
is believed that Aristotle may have observed this cluster in about
324 B.C. but it was first catalogued in 1654 by Giovanni Hodierna.
Charles Messier added this to his catalogue in 1765.