skyandtelescope.com • FEBRUARY 2020 25
the shadows cast by these streamers as they spiral through
the cone pointed toward us that are the likely source of
NGC 2261’s observed variations. Imagine what that might
look like from inside the nebula!
HVN’s Neighborhood
Hubble’s Variable Nebula is in a fascinating part of the sky.
It’s located about 1 ° from the open cluster NGC 2264 and
its associated H II nebulosity, Sh 2-273 (which is home to
the infamously challenging visual object, the Cone Nebula),
and, in fact, lies in the outer reaches of this H II region. But
that doesn’t mean it’s in a less dense environment, only
that the main illuminating star of Sh 2-273, S Mon, is too
far away to effi ciently energize Hubble’s Variable Nebula’s
immediate environment.
See For Yourself
Hubble’s Variable Nebula is about 2,500 light-years away
and, including the northern streamer, spans about 1.5 light-
years. It has an apparent size of 2′ — or about 2.5 times the
apparent diameter of Jupiter at opposition — and fl uctuates
around 9th magnitude. This relatively bright magnitude and
small apparent size together create a high surface bright-
ness, so don’t shy away from taking a look if you have a
scope of 8 inches or less. Even though the great 18th- and
19th-century visual observers like the Herschels or Lord
Rosse missed their opportunity to discover NGC 2261’s
More About the Sketches
The 21 sketches presented here were redrawn from the
originals in my observing notebook at the same scale so
they could be directly compared to one another.
The sketches that show the most fi eld stars represent
the best observing conditions with the 28-inch scope,
while the sketches with bloated stars represent the terribleseeing conditions of those nights.
Note that the two sketches of October 6, 2019, shown
below, illustrate what I saw with 28-inch and 8-inch f/4
scopes within a few minutes of each other — and confi rm
that an 8-inch scope can indeed present a good view of
Hubble’s Variable Nebula at high power.variability, you can watch the unfolding action through a
modest-size backyard telescope. You can’t know what you’ll
see if you don’t look, so do go look.
NGC 2261 is also a terrifi c astrophotography target. There
are several animations online (my favorite is the one by Tom
and Jennifer Polakis mentioned earlier), but at best they’re
composed of images taken months apart. An animation with
images taken on as many consecutive nights as possible, or
even more interesting, once every 30 minutes on the same
long winter night, could be fabulous.
Hubble’s Variable Nebula is well-placed in the northern sky
from late fall to early spring, so when the cold tempts you to
stay inside, bundle up anyway, grab your telescope, and watch
night to night as this exceptional object hurtles through its
extraordinary youth.¢ Contributing Editor HOWARD BANICH is enthralled by the
shifting shadows of Hubble’s Variable Nebula and hopes you
get hooked on them, too.OTHER VARIABLE NEBULAE: If Hubble’s Variable Nebula
inspires you to seek out further examples of this type of object,
you can also visually follow NGC 1555 (Hind’s Variable Nebula),
NGC 6729, GM 1-29 (Gyulbudaghian’s Nebula), and McNeil’s
Nebula. More information can also be found in Ted Forte’s article
in the February 2018 issue of Sky & Telescope (page 22) and at
https://is.gd/ReinerVogel.October 2, 2019
8-inch f/4 at 351×October 6, 2019
28-inch f/4 at 457×October 6, 2019
8-inch f/4 at 351×October 7, 2019
28-inch f/4 at 605×