Virgo Cluster
Virgo Cluster - Due to limitations of this website platform, the resolution of the above image is ‘only’ 54 MP. For full resolution, click here for the 240MP version.*
The Virgo Cluster is a cluster of galaxies whose center is 53.8 Million lightyears away in the Virgo constellation. Comprising approximately 1,300 (and possibly up to 2,000) member galaxies, the cluster forms the heart of the larger Virgo Supercluster, of which the Local Group (containing the Milky Way galaxy) is a member. The Local Group actually experiences the mass of the Virgo Supercluster as the Virgocentric flow. It is estimated that the Virgo Cluster's mass is 1.2×10^15 M☉ out to 8 degrees of the cluster's center or a radius of about 2.2 Mpc. Many of the brighter galaxies in this cluster, including the giant elliptical galaxy Messier 87, were discovered in the late 1770s and early 1780s and subsequently included in Charles Messier's catalogue of non-cometary fuzzy objects. Described by Messier as nebulae without stars, their true nature was not recognized until the 1920s. The cluster extends across approximately 8 degrees centered in the constellation Virgo.
source: Wikipedia
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Galaxy Cluster
Virgo
12h 30m 00s
+12° 50.0′
53.8 million ly
n.a.
01 May
65º S
Explore
The Virgo Cluster is a massive region packed with galaxies. Using the 0.72x reducer on the FSQ-106, in combination with a full frame camera, can capture a lot of that area in one image. Markarian’s chain, typically already a large target to capture in one go, only covers a small portion of this photograph. The only way to do this image justice, is to explore its details by zooming in. One way is to click here for a full resolution version. Another way is to explore the below image, where 24 of the largest galaxies in this cluster have been extracted from the image. This includes 7 Messier objects, and 19 NGC objects.
The Virgo Cluster is packed with galaxies, including Markarian’s Chain, 7 Messier objects and countless NGC galaxies. This graphic shows an overview of 24 of the biggest objects in the area, each showing a small extracted image from the total photograph. If you like to explore yourself, the best way is to scroll through the full-resolution version.
Conditions
The Virgo cluster is best observed in late winter, early spring. From The Netherlands, it can reach 65° in the sky. It was photographed from the backyard observatory in Groningen during several clear nights in a row, which is unusual nowadays. While the moon was present at around 50% illumination, there was enough angular distance from the moon, to not interfere too much with the image. Images for this photograph were taken on three different nights in early March 2025.
Equipment
The rig that was used in previous nights for Sh2-230 was continued to be used for this image. It consisted of a Takahashi FSQ-106 with 0.72x reducer, in combination with a ZWO ASI6200MM-Pro full-frame camera. This combination creates a field of view of 5.6 x 3.7°, large enough to capture Markarian’s chain and a wide area around it.
Telescope
Mount
Camera
Filters
Guiding
Accessoires
Software
Takahashi FSQ-106, 645 Super Reducer-QE 0,72x, Pegasus Astro Motor Focus kit v2
10Micron GM1000HPS, EuroEMC S130 pier
ZWO ASI6200MM Pro, cooled to -15 ºC
Antlia 2” unmounted LRGB, V-Pro, ZWO EFW 7-position
Unguided
Fitlet3, Pegasus Ultimate Powerbox v2, DeepSkyDad Flatpanel FT1 (30cm), Pegasus Uranus
Linux Mint 21.1, KStars/Ekos 3.7.5, INDI Library 2.1.2, Mountwizzard4 3.2.7, PixInsight 1.9.3
Imaging
From an imaging standpoint, not much special happened here. Standard settings were used for this broadband imaging. That includes 5min subs for the three colours and 3min for the luminance. Across the three sessions, almost 19h of data was collected, which is quite unique for the backyard observatory.
Resolution
Focal length
Pixel size
Resolution
Field of View
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Image center
19152 × 12776 px (244 MP, after drizzling)
382 mm @ f/3.6
1.88 µm (after drizzling)
1.018 arcsec/px
5d 25' x 3d 36'
-31.2°
RA: 12h 28m 39.323 s
Dec: +12° 58’ 50.64”
Processing
All images were calibrated using Darks (50), Flats (50) and Flat-Darks (50), registered and integrated using the WeightedBatchPreProcessing (WBPP) in PixInsight. All further processing was done in PixInsight, including the use of scripts and tools developed by RC-Astro, SetiAstro, GraXpert, and others. For a step-by-step description of the processing techniques applied, see process flow below.
The 645 Super Reducer-QE 0,72x from Takahashi is an impressive piece of glass, but unfortunately, it is certainly not free of distortions towards the edges of the frame on a full-frame camera. Fortunately the star correction capabilities of BlurXTerminator do a fantastic job to bring star shapes back to pretty decent round stars, all the way to the edges. Another effect of the reducer is that the already fairly high pixel scale of the FSQ-106 is increased even more. With the 0.72x reducer, the pixel scale is 2 arcsec/pixel. This makes for some pretty blocky stars. Therefore the WBPP script was instructed to process a 2x drizzle. Unfortunately PixInsight crashed just before the drizzling would start, so a manual drizzle integration was applied. The improvement in image quality from the drizzling is amazing. It increases the megapixel count to a whopping 240 MP. Due to limitations of this website builder, the maximum resolutions of images is 60MP. So to fully appreciate the nuances of the image, please check out the full resolution version.
The high brightness of the sky, due to a 50% moon illumination meant that the background signal relative to the star signal was quite high. This also means that irregularities in the background quickly become visible during stretching, especially for the luminance channel. For that reason, when the luminance was starless, the clonestamp tool was used to correct some of these irregularities. An interesting finding was that the results of the Seti Astro Statistical Stretch tool came out a lot better than the stretch tool from Bill Blanshan. Usually they yield very comparable results and I tend to use the Bill Blanshan script. But with this irregular background, I was able to achieve noticeably better results with Statistical Stretch. Stretching the RGB image was done with GHS for the most part. The ‘Colour’ mode is so much better in retaining colour in the image. And since this image is not too colourful to begin with, maintaining any colour that exists is paramount.
The rest of the processing followed a pretty standard workflow.
Processing workflow (click to enlarge)
This image has been published on Astrobin
