Astronomy - June 2015

(Jacob Rumans) #1

64 ASTRONOMY • JUNE 2015


ASTROSKETCHING
BY ERIKA RIX

Galaxy groupings


Galaxy season has arrived! The
Virgo Cluster alone provides
an abundance of sketching tar-
gets, frequently with multiple
systems captured in a single
field of view. Rendering such
groupings can be a breeze if
you break the process into
manageable steps. A good
combo with which to build
experience is NGC 5774 and
NGC 5775, a contrasting pair
of interacting spirals 2.5°
northeast of the star 109
Virginis near the Maiden’s foot.
Although both are of simi-
lar size and magnitude, you’ll
likely spot edge-on NGC
5775 first, along with a 13th-
magnitude star 1' northeast
of its midline. NGC 5774 lies
4.5' farther northwest, but due
to its face-on orientation, it
has a lower surface brightness
and may prove difficult to see
through a 6-inch telescope.
When framing the galaxies
in the eyepiece for your sketch,
try placing one or two promi-
nent stars near the edge of the
field of view. Doing so makes it
easier to return to the exact
star field when using a non-
tracking mount. Plot the
brightest stars first while cross-
referencing their magnitudes


and positions. Imagining a
clock face or geometric shapes
and lines connecting the stars
will help with accuracy.
Once you’ve placed enough
stars for reference, draw the first
galaxy. NGC 5775 extends 4' in a
northwest to southeast orienta-
tion so that, as labeled in the
image at right, it crosses midway
and beyond the imaginary lines
connecting stars B to D and B to
C. It’s also nearly in alignment
with the star at point A.
Lightly mark the galaxy’s
position on the sketch using an
eraser shield as a straight edge.
Rub the tip of a blending
stump through a patch of
graphite created outside the
sketch circle, and then use it to
draw the galaxy, adjusting its
pressure as needed for bright-
ness. If you observe an elon-
gated, central brightness, use
the eraser shield once again to
draw a darker line through the
galaxy. Remember, you’re actu-
ally creating a negative draw-
ing when using graphite on
white paper, so dark markings
represent brightness.
NGC 5774 spans 3.0' by 2.5'
and appears as a faint circular
glow that, when increasing the
aperture to 16 inches, brightens

with a soft core. If you draw an
imaginary line between the stars
at points A and E, the galaxy is
slightly offset northwest of it.
Starting at the galaxy’s cen-
ter, render its faint glow with a
loaded blending stump. Work
your way gradually outward in
a circular motion. You can
adjust the stump’s pressure and
add more graphite for bright-
ness as needed.

Complete the sketch by add-
ing the remaining star field,
and, if desired, use a blending
stump to produce a soft glow
around the brightest stars. For a
challenge, try capturing spiral
galaxy IC 1070 just 4' southwest
of NGC 5775. At 14.4 magnitude
with a 36" by 18" spread, it’ll
appear as a very faint smudge
with averted vision.
Happy galaxy hunting!

The author used the edge of an eraser shield to mark the midline of NGC 5775 (left), and then used a blending stump to produce the body of the galaxy (middle). NGC 5774,
additional stars, and soft glow around the brightest stars complete the sketch (right). She scanned the final version and cleaned up rough edges of stars using Photoshop.


In the first stage of her sketch of galaxies NGC 5774 and NGC 5775 in the Virgo
Cluster, the author has plotted only the brightest stars to orient the field of view. She
labels a few of these stars to help you envision where the galaxies will be placed. The
author used a 16-inch f/4.5 reflector on a Dobsonian mount for the observations,
with a 12mm eyepiece for a magnification of 150x. The author used white printer
paper, a black superfine felt-tipped artist pen, a #2 pencil, and a 0.5mm mechanical
pencil. The sketch is oriented so that north is to the left and west to the top.
ALL SKETCHES/PHOTOS: ERIKA RIX

E


A D


B C

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