The Caldwell Objects

fuzzy patch of light with the unaided eye. Even
the 19th-century observer, Rev. T W Webb . said
NGC 2244 is" [b] eautiful; visible to the naked
eye," though he too missed the nebulosity
around it, as did Adm. William Henry Smyth.
Did Messier and the Herschels largely ignore the
naked-eye sky? Perhaps this would explain why
Messier missed the 1758 return of Hal-ley's
Comet; as Messier searched telescopical-ly from
Paris, a German farmer and amateur astronomer,
Johann Georg Palitzsch, picked it up a
month before Messier — and he did so with the
unaided eye. Or perhaps the answer lies in the
biology of the eye itself. I have often wondered if
our eye-brain system has evolved over the last
few centuries to become more sensitive to faint
cosmic light. This would certainly explain some
other deep-sky mysteries, such as Galileo's
missing out on seeing the Orion Nebula and
Huygens's having found that the Orion Nebula
"cannot be well observed except with large
telescopes."
The Rosette Nebula has an equally intriguing
history, for it was discovered piecemeal. The first
person to notice any of it was Albert Marth, an
assistant to William Lassell on the
Mediterranean island of Malta. Using Lassell's
48-inch speculum-metal reflector in 1864, Marth
noticed a faint star embedded in a small patch of
bright nebulosity (NGC 2238) in the
northwestern quadrant of what we now call the
Rosette. Nineteen years later American comet
hunter Edward Emerson Barnard picked up a
larger part of the nebula in the northwestern
quadrant (NGC 2237).
But unknown to Barnard the same piece had
been discovered years earlier by another
American comet hunter, Lewis Swift of New
York. In his excellent Barnard biography, The
Immortal Fire Within: The Life and Work of Edward
Emerson Barnard, William Sheehan documents
these independent discoveries:
49 & 50
[On] January 23, 1883, Barnard encountered a large and
fairly bright nebulous object near the star 12
Monocerotis, and entered in his observing book:
"Found a large nebulous object, [near] a scattering
cluster of bright stars; it is elongated southwest and
northeast. Larger than the field of view." Finding no
such object in any of the catalogs, Barnard assumed,
naturally enough, that he had found a comet, and he
kept it in his sights much of the night looking for the
telltale signs of its motion. But it remained stationary.
Several more nights of observation put its nebular
identity beyond doubt, and on writing to Swift,
Barnard learned that his mentor had himself seen the
nebula many years before but had never published an
account of it. As Swift explained: "I did not know for a
certainty that it was never recorded but took it for
granted from its immense size that it was although I
never could find a description that fitted it." He [Swift]
finally published a note about it in the Sidereal
Messenger in 1884. He there described it as "a nebula
of the dumb-bell type, and . . . very large, one of the
largest visible from this latitude," and added that "it is
unaccountable to me that so conspicuous a nebula
should have so long been overlooked. About eighteen
months ago Mr. Barnard, now connected with the
Vanderbilt Observatory. . . in his sweeps for comets,
picked it up and called my attention to it, thinking it
might possibly be a comet." Barnard's discovery, then,
was entirely independent [of Swift's].
Scanning the area again in 1886, Swift found
a bright patch of nebulosity (NGC 2246) in the
eastern quadrant. But it was not until Barnard
was at Lick Observatory in the early 1890s that
the full extent of the Rosette Nebula became
known. First his visual observations with the 12inch
refractor confirmed that what he and Swift
had seen "was simply a brightish
The Caldwell Objects 197