NGC 5371 & the Hickson 68 Galaxy Group
Key Field Data
Main galaxy: NGC 5371
Notable galaxy group: Hickson Compact Group 68 (HCG 68)
Constellation: Canes Venatici
NGC 5371 type: barred/intermediate spiral galaxy
NGC 5371 distance: approximately 100 million light-years
HCG 68: compact group of interacting galaxies
Principal HCG 68 members: NGC 5350, NGC 5353, NGC 5354, NGC 5355 and NGC 5358
Additional prominent galaxy: NGC 5395, part of the interacting pair Arp 84 with NGC 5394
Field characteristic: exceptionally rich extragalactic background
Light-travel time: roughly 100 million years for the principal systems
Description
This deep image covers an exceptionally rich region of the constellation Canes Venatici, where several prominent galaxies share the field with dozens of much fainter systems.
The large spiral galaxy towards the lower-left is NGC 5371, while the striking concentration near the upper part of the image is Hickson Compact Group 68. Elsewhere in the frame, additional spiral and edge-on galaxies appear at different distances, surrounded by an extensive population of tiny background galaxies.
Unlike a photograph centred on a single isolated object, this field offers a broader view of the extragalactic environment, showing galaxies with very different morphologies and apparent sizes within the same image.
NGC 5371 – The Dominant Spiral
NGC 5371 is the largest and most visually prominent individual galaxy in the photograph.
Located roughly 100 million light-years away, it presents a broad spiral structure surrounding a bright central region. Its arms are relatively open and somewhat asymmetric, with subtle dust structures and knots of younger stellar populations visible across the disc.
NGC 5371 is physically associated with the wider concentration of galaxies in this region and is often considered part of the same larger environment as HCG 68.
Its appearance provides an interesting contrast with the compact grouping above it: NGC 5371 is seen as a single extended spiral, while HCG 68 compresses several substantial galaxies into a remarkably small area of sky.
Hickson Compact Group 68
Near the upper part of the image lies Hickson Compact Group 68, one of the most visually attractive compact galaxy groups accessible to amateur astrophotography.
A compact group is not simply a chance collection of galaxies appearing close together. Its principal members occupy a relatively small region of space and are sufficiently close for their mutual gravity to influence their evolution.
HCG 68 contains five principal galaxies: NGC 5350, NGC 5353, NGC 5354, NGC 5355 and NGC 5358.
Their different shapes are readily apparent. NGC 5350 is a face-on spiral, while NGC 5353 and NGC 5354 form the bright close pair beside it. The smaller NGC 5355 and NGC 5358 complete the group.
Seen together, they provide a miniature gallery of galaxy morphology within a remarkably confined area.
Galaxies in a Crowded Environment
Compact groups are especially interesting because gravity acts differently in such crowded environments.
Over immense periods, close encounters can disturb stellar orbits, redistribute gas, alter the appearance of galaxies and sometimes eventually lead to mergers. A galaxy's evolution is therefore influenced not only by its own stars and gas but also by the company it keeps.
HCG 68 offers a nearby example of this process. Its members remain distinct galaxies, but their close arrangement provides astronomers with an opportunity to investigate how repeated gravitational encounters affect galactic evolution.
The contrast with the relatively isolated appearance of NGC 5371 makes this field particularly effective at illustrating the difference between a large individual spiral and a dense galactic neighbourhood.
More Than Two Targets
NGC 5371 and HCG 68 immediately attract attention, but a closer inspection reveals that the photograph contains many other galaxies.
A particularly conspicuous spiral is visible toward the right-hand side of the image, while several edge-on systems appear as narrow streaks of light. Near the top-left and throughout the background are still more distant galaxies, some reduced to tiny diffuse patches only a few pixels across.
One interesting system in the wider region is NGC 5394 and NGC 5395, collectively catalogued as Arp 84. Their distorted structures are the result of a gravitational encounter between the two galaxies.
The deeper one looks into this photograph, the less the apparently empty black background resembles empty space.
A Natural Galaxy Survey
This image is particularly effective as a small galaxy survey.
Large spirals reveal arms and internal structure; inclined galaxies show flattened stellar discs; edge-on systems appear as thin streaks; elliptical and lenticular galaxies present smoother distributions of light; and the most distant objects shrink into barely perceptible smudges.
The sharp stellar points scattered across the frame are predominantly foreground stars belonging to the Milky Way, vastly closer than any of the galaxies behind them.
One of the brightest foreground stars lies almost directly over the HCG 68 region, creating a dramatic visual juxtaposition: a single nearby star can appear brighter than entire galaxies containing billions of stars simply because it is enormously closer to us.
Why Compact Groups Matter
Hickson Compact Groups are named after astronomer Paul Hickson, who published a catalogue of 100 compact galaxy groups in 1982.
They were selected because they contain several galaxies packed into a small angular area while being relatively isolated from the surrounding galaxy population. This makes them valuable laboratories for studying interactions and mergers.
HCG 68 is especially attractive visually because its brightest members are sufficiently large and distinct for their different forms to be recognised directly in deep amateur images.
The group demonstrates an important principle: galaxies are not immutable structures. Over billions of years, gravity can reshape them, strip material from them and ultimately combine them into entirely new systems.
Looking Back in Time
Most of the prominent galaxies in this field lie roughly 100 million light-years from Earth, meaning that we see them as they existed around 100 million years ago.
At that time, Earth was in the Cretaceous Period. Dinosaurs dominated terrestrial ecosystems, flowering plants were spreading across the continents, and Homo sapiens lay almost 100 million years in the future.
While life on Earth followed that evolutionary path, photons left NGC 5371 and the galaxies of HCG 68 and began crossing intergalactic space.
The smallest background galaxies in the photograph may be considerably farther away, meaning that their light began its journey at even earlier periods of cosmic history.
The image therefore does not contain a single depth or a single moment in time: it is a view through successive layers of the Universe, each recorded at a different epoch.
Image Data
Total integration time: 21h 55m
Integration by filter:
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L-Pro: 2h (24 × 300")
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Red: 4h 2m 20s
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Green: 7h 28m 20s
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Blue: 8h 24m 20s
Equipment:
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Telescope: Artesky ARTEC 250 Pro
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Camera: ToupTek ATR2600M
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Mount: 10Micron GM2000 HPS II
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Filters: Optolong Blue 2", Optolong Green 2", Optolong L-Pro 2", Optolong Red 2"
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Accessories: Pegasus Astro Prodigy Microfocuser, ToupTek AFW-L 7×2", WandererAstro WandererBox Pro V3
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Software: Adobe Photoshop, Pleiades Astrophoto PixInsight, Stefan Berg Nighttime Imaging 'N' Astronomy (N.I.N.A. / NINA)
For further details and the full-resolution image, visit AstroBin: