From the April 2020 issue

Observing Virgo: A brief guide

Spring is galaxy season, and no constellation proves it better than this one.
By | Published: April 7, 2020 | Last updated on May 18, 2023
NGC 4216
Adam Block/Mount Lemmon SkyCenter/University of Arizona
It’s difficult to conceive of how large Virgo is. The Maiden is the second-largest constellation, covering 3.1 percent of the sky. It contains 11 Messier objects, tons of worthy targets from the New General Catalogue, and more faint galaxies than you can count.

In this brief guide, I want to remove the intimidation of this constellation’s size and provide a list of the best objects to point your scope at. I list them in order of increasing right ascension. That means the westernmost objects come first and, as you observe, the latter ones rise higher in the sky.

Please note that I don’t include any elliptical galaxies in this story. They’re still plotted on the map you’ll find on the following paragraphs, but I describe the best of them in “The sky’s best elliptical galaxies.”

Adam Block/Mount Lemmon SkyCenter/University of Arizona

A crowded field

Our first object is the Silver Streak Galaxy (NGC 4216). It lies at the western edge of the Coma-Virgo Cluster of galaxies. From a dark site, a 10-inch telescope will reveal several hundred galaxies here, so take your time and be sure of your identification.

NGC 4216 appears as a magnitude 10 streak of light nearly five times as long as it is wide (7.8′ by 1.6′). The core is bright, but to see its bulge will require a 12-inch or larger scope. Look for 12th-magnitude NGC 4206 12′ to the southwest of NGC 4216. It has a similar appearance to its brighter neighbor.

The next target is M61, the first of four Messier objects on our list. It glows at magnitude 9.7 and measures 6.0′ by 5.9′. This is a face-on spiral galaxy; however, its arms wind tightly around the core, so it doesn’t look nearly as good as others of this type. That said, a 12-inch telescope will allow you to see the stubby extensions of two arms. Through really big scopes at high magnification, look for a thick bar that runs north-south through this object.

NGC 4435 and NGC 4438
Our next object — NGC 4429 — lies in the heart of the Virgo Cluster. It’s an attractive spiral that measures twice as long as it is wide (5.8′ by 2.8′) and glows at magnitude 10.2. When you observe it, you’ll spot two nearby 9th-magnitude stars. SAO 100102 lies 2′ to the north-northeast, and SAO 100103 lies 5′ to the south-southeast.

The core of this galaxy spans roughly one-third of its length. You’ll also notice that the halo region is more apparent than in similar spirals. An 8-inch telescope is a great instrument for viewing NGC 4429 at a dark site. Crank up the power past 250x to see all of its details.

Less than 2° north of NGC 4429 you’ll find NGC 4435 and NGC 4438, a pair of galaxies called the Eyes. The two glow at magnitude 10.2 and 9.7, respectively, and they’re not small, spanning an area 8.5′ by 3′. Some millions of years ago, these star cities came within 16,000 light-years of each other. If you can view them through a 12-inch scope, try to spot the distorted outer regions of NGC 4438.

NGC 4535
Adam Block/Mount Lemmon SkyCenter/University of Arizona
Done with the Eyes? Head 5° south for the Lost Galaxy (NGC 4535), which often gets overlooked by observers. It glows at magnitude 10.0 and measures 7.0′ by 6.4′. This barred spiral boasts a core that far outshines the arms. Through a 12-inch or larger scope, you might notice the central region looks rectangular. Crank up the power beyond 300x, and you’ll spot two faint spiral arms that begin at the ends of a bar. Also, the northern arm contains a 13th-magnitude star some amateurs have thought is a supernova. Unfortunately, it’s just a foreground star in the Milky Way. The “Lost Galaxy” moniker comes from American amateur astronomer Leland S. Copeland, who wrote that it had a “hazy phantom-like appearance in the amateur telescope.”
NGC 4536
Adam Block/Mount Lemmon SkyCenter/University of Arizona
Next up is the unusual spiral NGC 4536. It glows at magnitude 10.6 and measures 6.4′ by 2.6′, with arms that extend nearly straight out from the core. Near the core, they appear thick and bright. One-third of the way from the core to each arm’s end, however, their brightness and thickness decrease dramatically. A 7th-magnitude star (SAO 119485) sits just 13′ east-northeast of this galaxy.
NGC 4567 and NGC 4568
Ken Crawford
For a wonderful example of interacting galaxies, turn your telescope toward the Siamese Twins (NGC 4567 and NGC 4568). Under a dark sky, even a 6-inch scope will reveal their overall V shape. To see any detail, however, you’ll need a 12-inch or larger instrument. You can tell these two galaxies apart by remembering that NGC 4568 appears slightly brighter (magnitude 10.9 vs. magnitude 11.3) and a bit longer (4.3′ vs. 3.1′) than its companion.
Paul and Daniel Koblas/Adam Block/NOAO/AURA/NSF

Oh, boy! Our second Messier object is next. Unfortunately, M90 may be one of the least interesting spiral galaxies you’ll ever observe. That’s too bad, because we tend to expect more from Messier objects. It glows reasonably bright for a galaxy, at magnitude 9.5. And it has some size, too, measuring 10.5′ by 4.4′.

What you’ll see is an object that measures two times as long as it is wide. M90’s spiral arms wind tightly around it, however, so unless your scope’s mirror measures 2 feet across, be content to just check this bright galaxy off your list and move on.

Adam Block/Mount Lemmon SkyCenter/University of Arizona
Next on the list, the barred spiral M58 doesn’t rate much higher than M90. It glows at magnitude 9.6 and measures 5.5′ by 4.6′. Just about any size telescope will show M58’s slightly oval structure. Through a 16-inch or larger scope, you should be able to pick out the brighter central bar. Around the bar, a faint halo region represents the galaxy’s tightly wound spiral arms.

South and east

The fourth and final Messier object on our list, the Sombrero Galaxy (M104), is anything but a disappointment. This spiral glows at magnitude 8.0 and measures 7.1′ by 4.4′. It’s a great object to show off through a medium-sized scope, but do wait until it stands highest in the south.

M104 was the first galaxy for which astronomers detected a large redshift. Redshift measures the speed of an object away from us, caused by the universe’s expansion. In 1912, American astronomer Vesto M. Slipher discovered that the Sombrero Galaxy was moving away from us at a speed of 2.2 million mph (3.6 million km/h).

M104’s lens shape and the dark dust lane that splits it are easy to spot. The galaxy’s two sections have unequal brightnesses — the north outshines the south because M104 inclines 6° to our line of sight. The dust lane, therefore, appears to cross south of center.

Through a 4-inch telescope, you may detect the dust lane only near the Sombrero’s center. The core is bright and a large halo surrounds it, extending above and below the sections of the spiral arms nearest the nucleus.

The next target, Gamma (γ) Virginis, called Porrima, is one of the most famous double stars in the sky. This binary has been the subject of much research, and astronomers have even written poems about it. Nineteenth-century Royal Navy Admiral William Henry Smyth in his Cycle of Celestial Objects devotes eight pages to this double star. Both components shine at magnitude 3.5 and the separation between them is 2.9″.Make a note to revisit Gamma Vir every year or two. The pair is widening and by 2030, the separation will increase to 3.9″.

Next up, NGC 4731, is not a bright galaxy (magnitude 11.5) but it has several features I think you’ll find worth your observing time. It appears as a highly distorted S shape because it doesn’t travel through space alone. You’ll easily spot its brighter companion: Look only 0.8° to the northwest for magnitude 9.2 NGC 4697, an elliptical galaxy I describe on page 61. Gravitational interaction between these two has nearly destroyed NGC 4731’s spiral arms.

Through a 10-inch telescope, observe NGC 4731’s long, relatively bright central bar. If your observing site is dark, crank up the power past 200x and look at the wide, irregular spiral arms that originate from each side of the bar.

The western arm appears somewhat brighter. Tiny bright patches within both arms signal hotspots of star formation. Through a 20-inch or larger telescope, use a nebula filter to increase the contrast of those regions and the galaxy’s older stars.

If you want to show someone an edge-on galaxy, the next object on our list will do nicely. Barred spiral NGC 4762 glows at magnitude 10.3. More than four times as long as it is wide (9.1′ by 2.2′), NGC 4762 appears as a white line through medium-sized telescopes.

You won’t see a central bulge through any size scope. All you will notice is that the core appears ever-so-slightly brighter than the arms.

Next up is NGC 4856, a magnitude 10.4 spiral that lies near Virgo’s western border with Corvus. Through an 8-inch telescope at 200x, you’ll see a disk with a small, bright central region. The galaxy stretches more than three times as long as it is wide (4.3′ by 1.2′) in a northeast-to-southwest orientation. For those of you using 14-inch or larger scopes, crank the power past 350x and look for a magnitude 13.1 foreground star just barely east of the core.

At magnitude 13.9, you might be inclined to skip the next target, planetary nebula IC 972, for less difficult fare. That’s fine if you’re viewing through a 4-inch scope, but if you have a 10-inch or larger instrument, have a look at the faint outer layers of this once Sun-like star. Because of its small size (43″), IC 972 has a reasonable surface brightness. Better known as Abell 37, this object appears uniformly illuminated with a sharp edge.

NGC 5634
Dan Crowson
Our final target is globular cluster NGC 5634. If we’re being honest, Virgo is known for its galaxies. The constellation contains some 200 deep-sky objects brighter than 13th magnitude. Only one — magnitude 9.5 NGC 5634 — is a globular cluster.

Point a 4-inch telescope at it, and you’ll see lots of faint stars and one bright orange one — magnitude 8.0 SAO 139967, which sits a bit more than 1′ east-southeast of the cluster’s center. The star isn’t part of NGC 5634, it just happens to lie in the same direction from our viewpoint.

The cluster’s stars are condensed, meaning you won’t easily resolve them into individual points. But the back-and-forth visibility battle you’ll encounter between the star and the cluster makes for a fascinating observation.
As you’ve probably inferred, there are a great many more targets in Virgo. The ones on this list, however, should keep your scope pointed in this constellation’s direction for a full night. Take your time, sit comfortably as you observe, and enjoy the view.