Andrew Cooper
Mar 2, 2019    Kaʻohe, Mauna Kea, HI (map)
28cm f/10 SCT, NexStar 11" GyPSy @ 127x
Seeing: 6 Transparency: 7 Moon: 0%

A lovely cluster centered on the bright star τCMa, a hundred or so stars in 10' area, Tau itself is a bright blue-white at mag 4.4 with a dim companion at mag 10 just 8" away

Andrew Cooper
Feb 6, 2018    Waikoloa, HI (map)
20cm f/6 Newtonian, Cave Astrola @ 127x
Seeing: 7 Transparency: 7 Moon: 0%

A distinctive cluster huddled closely around the bright τCMa, a triangular shaed area 5' on a side filled with 7-10th magnitude stars, bright, resolved, coarse, and lovely

Andrew Cooper
Mar 29, 2016    Waikoloa, HI (map)
28cm f/10 SCT, NexStar 11" GyPSy @ 127x
Seeing: 7 Transparency: 6 Moon: 0%

A beautiful cluster groupd around τCMa, bright, coarse, fully resolved, about 30 stars arranged in an area about 10' in diamter centered on the bright star, Tau itself is blue-white at 4.4 magnitude, there is an 8th magnitude companion 1' east

Andrew Cooper
Nov 17, 2009    Hale Pohaku, HI (map)
46cm f/4.5 Newtonian, Deep Violet @ 95x
Seeing: 7 Transparency: 7 Moon: 0%

Beautiful in a big 'scope and a dark sky, a bold cluster in a heavy starfield, a few dozen bright members clustered around the bright τCMa (mag 4.4), <10' in diameter and triangular in shape

Andrew Cooper
Feb 9, 2007    Waimea, HI (map)
76mm f/6 APO

Splendid cluster set off by and centered on τCMa, a dense triangular cluster, resolved, brighter members embedded in a bright haze, grand region at the base of CMa, h3945 located just north.

Andrew Cooper
Mar 30, 2002    Sycamore House, Tucson, AZ (map)
20cm f/10 SCT

Excellent cluster centered on the 4th magnitude star Tau CMa, a couple dozen 9th and 10th magnitude stars arranged in a triangular area 5' across, empty zone near Tau except for one close companion, somewhat sparse, bright, a favorite star party object for me

Captain William Henry Smyth
Oct 30, 1834    No. 6 The Crescent, Bedford, England (map)
150mm f/17.6 refractor by Tully 1827

A star with a companion [τ CMa], in cluster 17 ♅. VII., on the Greater Dog's back; where a line from Bellatrix through Sirius, and 12° beyond, will find it. A 6½, white; B 9, pale grey. The whole has a beautiful appearance, the bright white star A being surrounded by a rich gathering of minute companions, in a slightly elongated form, and nearly vertical position. The latest investigations into the proper motions of this star, destroy the amount formerly attributed to the declination, and reduce that in RA to about +0".06 per annum. [Hipparcos data shows -2.31 mas in RA and 5.02 mas in dec]

― A Cycle of Celestial Objects Vol II, The Bedford Catalogue, William Henry Smyth, 1844