Astronomy - February 2014

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ASTROSKETCHING

BY ERIKA RIX

Realistic eyepiece sketches

“How do I make my eyepiece

sketches look more realistic?”

It’s a question observers often

ask when trying to re-create the

lifelike appearance of an eye-

piece view. Thankfully, our

images can benefit from several

methods. They include tech-

niques at the eyepiece, digital

enhancements, and drawing

tablets. In this month’s column,

I want to chat about the first of

the three — eyepiece techniques

— and I’ll take a couple exam-

ples from the constellation

Auriga the Charioteer.

The first is open cluster NGC

1778. At magnitude 7.7, it’s a
      fairly bright unconcentrated
      target with a low star count.
      Through an 8-inch telescope at
      150x, you’ll see a patch of 20
      stars stretching northwest to
      southeast. Through a 16-inch
      scope, 40 stars form two chains
      separated by a starless lane. The
      brighter northern chain has a
      10th-magnitude double at its
      northern end.
      Attention to detail is essen-
      tial for realistic sketches. So
      while you draw NGC 1778 and

its surroundings, you’ll want to

include as many stars as pos-

sible. Concentrate on

accurate placements

and correct magni-

tudes. The amount

you twist your

pencil along with

the pressure you

apply regulate star

brightness.

For added

dynamic range, try

a superfine black

felt-tipped artist’s pen

for the brightest stars, a

#2 pencil for the medium-

bright ones, and a 0.5mm

mechanical pencil for the faint-

est. A blending stump lightly

loaded with graphite will softly

illuminate the brighter stars.

Place the tip over the star.

Then, with a light circular

motion, create a diffuse

“glow” around it.

Now that you’ve fin-

ished a star cluster, you

can tackle nebulosity.

The object I’ve cho-

sen is NGC 1931, an

emission nebula

coupled with a

young open cluster.

You’ll find it 0.8°

east-southeast of

magnitude 5.1 Phi

(φ) Aurigae. The neb-

ulosity surrounds a

tiny open cluster that

contains only five bright

stars. Amateur astrono-

mers aptly refer to this pair

as the Spider and the Fly.

Through an 8-inch telescope,

you’ll see a 1' glow surrounding

an 11th-magnitude star. It lies 3'

north of a star pattern resem-

bling the body of the constella-

tion Scorpius, which extends 10'

east to west. Peering through a

16-inch scope, you’ll notice that

the nebulosity elongates to

become brighter toward the

northeast and fainter to the

southwest. Four stars curve

northwest of the central star.

When sketching a diffuse

object, it’s important to build up

the nebulosity carefully. What

you want to do is illustrate the

subtle tonal variances and dif-

fuse boundaries that emission

(or reflection) nebulae are

known for. Drawing with a

graphite-loaded blending stump

works best. Add extra layers of

graphite as needed, then blend.

Learning tricks of the trade

like these will set you on course

for producing realistic eyepiece

sketches. In my next column, I’ll

focus on a pair of objects within

our solar system.

Do you have a sketching

question? Contact me via email

at [email protected].

Open cluster NGC 1778 will give you the opportunity to refine the placement and magni-

tudes of your sketched stars. For both of the sketches in this column, the author used a

16-inch f/4.5 reflector on a non-tracking Dobsonian mount and an 8mm eyepiece, which

gave a magnification of 225x. BOTH SKETCHES BY ERIKA RIX

NGC 1931 will take your sketching to the

next level. It combines a nebula and a

small star cluster. The author created

both of the sketches on this page using

white printer paper, a superfine black

felt-tipped artist’s pen, a #2 pencil, and a

0.5mm mechanical pencil. To capture the

star illumination and the subtle nebulos-

ity, she used a loaded blended stump.

She then scanned and inverted the

sketches and removed the jagged star

edges using Photoshop.