Sky & Telescope - December 2024 - 59

In Draco's Coils: FGC 2070,
FGC 2250, FGC 2255
Look some ¾° southeast about halfway
along the line connecting the 3rdmagnitude
stars Eta (η) and Zeta (ζ)
Draconis to find FGC 2070, a beautiful,
little, 14.3-magnitude edge-on galaxy
that deep images show is bisected by
a dust lane. Even on an exceptional
night with steady seeing conditions, I
was unable to detect the dark lane in
the Buffalo Astronomical Association's
20-inch telescope, the instrument I
used for all the observations included
here. The galaxy appeared as a long and
asymmetric slash through the sky background,
flanked by two rows of stars
as portrayed in my sketch below. (All
sketches represent the view through the
20-inch telescope and with north up.)
The westernmost of these stars is visual
magnitude 16.9, which indicates the
depth of view that our skies afforded
that night.
When observing flat galaxies, I find
myself using somewhat lower magnifications
than I usually employ on
challenging targets. In the best view at
250×, FGC 2070 displayed no distinct
core and tapered smoothly to its
pointed ends, only to continue after a
gap with a visually separated star cloud
to the northwest. Deep images show
this feature to be a bend in the spiral
arm. That's right: If you look for subtle
clues, you can detect spiral structure in
an ultra-thin galaxy 270 million lightyears
away!
Moving through our sampler in
increasing right ascension, we next
FGC 2070
250×, 6′
FGC 2070
FGC 2250
come to 14.2-magnitude FGC 2250.
It's in Draco, but you'll find it most
easily by pointing 2¾° north-northwest
of Kappa (κ) Cygni, which marks the
left wingtip of the Swan. The reported
major-to-minor axis ratios for this
galaxy run as low as 5.9 (a bit below
Karachentsev's seven-times cut-off), so
this is one of the galaxies in the catalog
that's not exactly edge-on. However,
classified as a late-type spiral, it lacks
a pronounced bulge in photos. In the
20-inch, I could see a small core that
was no brighter than the rest of the
galaxy, a shallow arc attached to it on
the north side and running west, and
a fainter, sharply curved arm on the
eastern end.
A diamond arrangement of four
stars lay to the galaxy's west, with the
easternmost star at magnitude 16. In
g-band images, whose spectral sensitivity
is similar to our dark-adapted vision,
the arms are clumpy, as is typical of
late-type spirals, with loosely wound
arms. Try increasing the magnification
under very dark skies to see if it will
show this fine structure to you.
FGC 2250
250×, 3′
FGC 2255
To arrive at our next target, move
north to 3.9-magnitude Epsilon (ε)
Draconis and from there another 21
/3
°
northeast to find 14.3-magnitude
FGC 2255. Images reveal a fine needle
with a fainter splinter of light separated
by a dark lane. Visually at 250×, I see
something more like a string of objects
that stretch east to west. The brightest
of these is at the position of the galaxy's
core. The thin feature shown in
my sketch below connects to the core
from the west, corresponding to the
arm that curves around that end of the
galaxy. On the eastern end, a droplet of
light seemingly dangled, barely connected
to the core. This is the opposite
arm, which in photos is separated by
the dark gap. The visual appearance
also captures the curvature of the
galaxy's southern edge - the three
light patches seem to be strung along
a shallow arc. When going for these
features, test the depth of your view
by looking for the dim companion to
the 14.5-magnitude star directly north
of the galaxy's core: It glows feebly at
magnitude 16.4.
FGC 2255
250×, 6′
sk yand tele scope .o r g * DECEMBER 2024 59
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Sky & Telescope - December 2024

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