The Caldwell Objects

60 & 61
more spectacularly, the Hubble Space Telescope
has revealed a brilliant fireworks show within the
dynamic duo. Hubble uncovered more than 1,000
bright, young star clusters bursting to life as a
result of the collision between NGC 4038 and
NGC 4039. The brightest of these clusters
contains roughly a million stars, all just a few
million years old. One cluster, in NGC 4038's
northern arm, looks like a miniature barred spiral
galaxy itself. Indeed, some of the system's
newborn clusters appear to be young globulars,
while others may ultimately congeal to form
globular clusters perhaps a billion years from
now. The Hubble images also show
unprecedented detail in the streams of reddish
dust bleeding across the comma-shaped surface
of NGC 4038 and fun-neling onto the core of
smaller NGC 4039.
What of this drama, if anything, can one see
through a small telescope? Certainly the details
of a distant galaxy merger are far too difficult to
see with anything but the largest of instruments
— right? When Walter Scott Houston observed
NGC 4038 and NGC 4039 through a 4-inch Clark
refractor from the "indifferent skies" of Haddam,
Connecticut, he saw "little more than an
asymmetrical 11th-magnitude blur." One
problem is that the galaxies have low surface
brightnesses; to see them well, we need to be
under dark skies and to have a lot of patience. Be
aware that an 11th-magnitude galaxy, NGC 4027,
lies about 45' southwest of the Antennae — one
of the duo's common nicknames — and is closer
to 31 Crateris than our targets are. Houston
suspected that many amateurs had sent him
descriptions of that galaxy rather than of the
Ringtail (yet another nickname for the galaxy
pair). You've got the correct object in view if it is
part of an arc of four roughly 9th-magnitude
stars flowing from 31 Crateris to the north-northeast.
(The first two stars form a roughly 5'-
242
wide pair 20' from 31 Crateris.) The Ringtail (or
the Antennae, if you prefer) is just south of the
fourth (and brightest) star in the arc. Those living
under dark skies might want to challenge
themselves by trying to see the pair in binoculars.
This is an especially good challenge for those
attending the Texas Star Party. I found them just
barely at the threshold of visibility in 7x35
binoculars from Hawaii. I have not read of any
other binocular sightings.
In the 4-inch at 23x, the Ringtail looks undeniably
double. Or is it more accurate to say it is
elongated, with a dark but tenuous wedge to the
west? The northwestern component, NGC 4038,
appears much brighter and larger than NGC 4039
to the southeast. (This supports the NGC
descriptions on page 239.) I'm certain that the
magnitudes given by the Deep Sky Field Guide
(and used in the table above) for the Antennae
are incorrect; they make NGC 4038 and NGC
4039 seem near-equals in brightness. Christian
Luginbuhl and Brian Skiff's Observing Handbook
and Catalogue of Deep-Sky Objects lists a magnitude
of 10.7 for NGC 4038 but does not provide one
for NGC 4039; Roger
Deep-Sky Companions: The Caldwell Objects