From the July 2015 issue

Sketch Minkowski’s nebulae

Erika Rix guides readers through sketching the challenges of small nebulae.
By | Published: July 27, 2015 | Last updated on May 18, 2023
If you caught my previous column, you may have tried your hand at using the white-on-black sketching technique for deep-sky objects. Now it’s time to step it up a notch. The challenge isn’t always in the complexity of the object, but rather its size.

In 1946, a German-American astronomer named Rudolph Minkowski (1895–1976) released a new list of 103 nebulae. He discovered these by examining objective-prism survey plates obtained by William C. Miller with a 10-inch refractor at Mount Wilson Observatory. With several interesting small nebulae to choose from, I’ll share two of my favorites.

Tucked within the parallelogram of the constellation Lyra is a beautiful 13th-magnitude planetary nebula, M1–64 (PK 64+15.1). At only 17″ in diameter, it’s often overshadowed by the more obvious Ring Nebula (M57). You can locate M1–64 nearly halfway between the Ring and Zeta (ζ) Lyrae.

The author sketched M1–64 here as seen through a 16-inch f/4.5 Newtonian reflector with a 8mm Plössl eyepiece and Oxygen-III filter, for a magnification of 225x.
The author sketched M1–M64 here as seen through a 16-inch f/4.5 Newtonian reflector with a 8mm Plossi eyepiece and Oxygen-III filter, for a magnification of 225x. She sketched both targets using a Gelly Roll 08 white gel pen, a white watercolor pencil, white charcoal, a No. 1 blending stump, and black Strathmore Artagain paper. She used a gel pen to draw 3.5-inch diameter sketch circles onto the paper. She removed the rough edges of the stars and added star glow in Adobe Photoshop. Sketches are rotated so that north is at the top, west is on the right.
All sketches by Erika Rix
Through an 8-inch telescope, it appears as a soft gray disk of uniform brightness. Its shell becomes detectable using a 12-inch scope, and when increasing the aperture to 16 inches, the nebula brightens to form a ring. Although the central star isn’t visible, you should be able to spot a faint star at its north rim. This object responds well to Oxygen-III and ultra-high contrast filters.

Smaller objects require precision sketching tools. Use a 1/8″ (No. 1) blending stump to apply a thin, round layer of white pastel within the star field to render the planetary’s disk. If you observe the shell, add its gentle glow softly with a white pencil.

Smaller yet is Minkowski’s Footprint (M1–92), a bipolar reflection nebula in the constellation Cygnus. Due to its diminutive 4.5″ by 11.5″ size, I used the magnitude 5.4 star 9 Cygni as a home base and then star hopped 20′ north-northeast until I recognized the ladle-like star pattern in which the nebula resides. A magnitude 9.7 star lies another 1′ farther north.

Minkowski's Footprint (M1-92)
For the observation of tiny nebula Minkowski’s Footprint (M1–92), the author used a 16-inch f/4.5 Newtonian reflector with an 8mm Plossi eyepiece and a 2.5x Barlow, for a magnification of 563x.
Looking through an 8-inch telescope, M1–92 is stellar, but it softens at 200x. You’ll notice an elongation using a 12-inch scope so that it resembles a close double. Pushing the magnification of a 16-inch scope reveals its distinctive footprint appearance, though depending on sky conditions, you may not see a separation. The northwest lobe is brighter and nearly two-thirds the size of its tapered southeast component.

I drew the large circular lobe with a white pencil and then blended with a No. 1 stump. I needed only slight dabs to soften its edges while leaving the center bright. I used the residue that remained on the stump’s tip to smudge in the heel.

Be sure to check out my next column for a demonstration on sketching solar prominences, and as always, feel free to share comments or questions with me at Clear skies!