Think positive | Astronomy.com

I have the tendency to be either too light- or heavy-handed with graphite when rendering deep-sky objects on white paper. It’s a coin toss as to how the object might look after inverting the scanned drawing to a positive image — the faint details could disappear, or the denser areas could become overly bright.

Switching to black paper eliminates the guesswork. By using white media in lieu of graphite, you can create a positive image directly at the eyepiece. Along with quality black paper and blending stumps, the basic sketch kit includes (in white) colored pencils, a gel pen, and a pastel or charcoal pencil. I’ll use a sketch of the Fetus Nebula (NGC 7008) as an example.

Reaching 98″ by 75″ across at magnitude 10.7, this bluish planetary nebula lies in the constellation Cygnus the Swan, nearly midway between Deneb (Alpha [α] Cygni) and Alderamin (Alpha Cephei). It’s nestled just next to the northern component of SAO 33060, a striking gold and blue binary star system with an 18″ separation.

The author captured NGC 7008 with a 16-inch f/4.5 reflector on a non-tracking Dobsonian mount, using an Oxygen-III filter and an 8mm Plössl eyepiece for a magnification of 225x. She sketched both targets using a Gelly Roll 08 white gel pen, a white watercolor pencil, a white Conté crayon, a No. 2 blending stump, and black Strathmore Artagain paper. The diameter of the sketch circle is 3.5 inches, and the sketches have been rotated so that north is at the top, west to the right.

All sketches by Erika Rix

Through a 4-inch instrument, NGC 7008 has a crescent shape and several nearby doubles. Nodules on the north-northeast and the south-southwest rims show through a 10-inch telescope, and 16-inch apertures reveal its magnitude 13.2 central star, along with superimposed stars on the western and eastern limbs at 13th and 14th magnitudes. Nebulosity contrast improves with an ultra-high contrast or Oxygen-III filter.

Following a typical sketch sequence, add the brightest stars first with a gel pen. The colored pencil is better suited for the dimmer stars because its waxy base produces fainter markings. Once the star field is complete, lightly rub the tip of a blending stump through a patch of pastel outside the sketch area, and then use it to draw the nebula.

The second sketch is of the Fireworks Galaxy (NGC 6946). It’s located 2° south-southwest of Eta (η) Cephei on the border between the constellations Cepheus and Cygnus. At low power, this face-on spiral fits in the same field of view as open cluster NGC 6939, just 39′ northwest. The galaxy’s high levels of star formation and destruction invoke the explosive displays for which it’s named.

The author observed the Firework’s Galaxy (NGC 6946) using a 16-inch f/4.5 reflector on a non-tracking Dobsonian mount with a 12mm eyepiece for a magnification of 150x.

Through a 4-inch scope, the Fireworks — at magnitude 8.8 and measuring 11.5′ by 9.8′ across — is a soft haze just north of a triangle of 7th- and 8th-magnitude stars. With a 10-inch instrument, its center brightens and the object becomes elongated east to west. A concentrated core and knotted arm structures are visible through a 16-inch telescope.

Drawing with pastel and charcoal produces a matte finish that smudges and erases easily. It also has the ability to accept multiple layers over itself. That translates to significant control with a blending stump while you build up the structural layers of the Fireworks Galaxy.

Questions, comments, or suggestions? Contact me at erikarix1@gmail.com.

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