Focus On Downtown Virgo

A Galaxy Cluster Extraordinaire
and an M87 Challenge

For any telescope

The Virgo galaxy cluster is without a doubt the richest region of bright galaxies in the sky. Situated between Denebola (at the tail of Leo) and Vindemiatrix in Virgo lie thousands of galaxies, roughly centered on the 10th magnitude M86.

Within a 5o radius of M86 lie at least 40 galaxies brighter than 12th magnitude, making this area a rich hunting ground for even the smallest of telescopes. From a dark site a 6-inch scope will show about 140 galaxies in this region and an 18-inch scope will reveal over 600!

To narrow things down a bit I'll concentrate on an area with a 2o radius of M86. I call this region Downtown Virgo.

Downtown Virgo
Right Ascension Declination Magnitude Size Con Distance
12h26m11.7s 12o56'49" 8.6 - ? ~4o Vir 50 million light years


The most difficult parts of observing in this region are finding a suitable starting point and  keeping track of where you are. I recommend M86 or M87 as good places to start (they are plotted on just about any atlas).

Users of smaller scopes (<6") should start with the brighter objects listed by Messier in the Virgo Cluster. They range from 9th to 11th magnitude.

Messier Galaxies in Downtown Virgo
Galaxy Mag Size Type
M49 9.3 9.8' x 8.2' Elliptical
M87 9.6 8.7' x 6.6' Elliptical
M60 9.8 7.6' x 6.2' Elliptical
M86 9.9 9.8' x 6.3' Elliptical c
M85 10.0 7.4' x 5.9' Lenticular
M100 10.1 7.5' x 6.1' Spiral c
M84 10.2 6.7' x 6.0' Elliptical a
M88 10.2 6.8' x 3.7' Spiral b
M90 10.2 9.9' x 4.4' Spiral b
M58 10.4 6.0' x 4.8' Spiral b
M99 10.4 5.3' x 4.6' Spiral c
M59 10.7 5.3' x 4.0' Elliptical
M91 10.9 5.2' x 4.2' Barred Spiral b
M98 10.9 9.4' x 2.3' Spiral b
M89 10.9 5.3' x 4.8' Elliptical

For larger scopes, the downtown region is like a treasure chest full of galaxies. The chart below shows all of the galaxies brighter than 12th magnitude within a 4o x 5o region surrounding M86.

Two of the standouts of downtown Virgo are M87 and the Siamese Twins. The Twins are a pair of interacting galaxies. 

The M87 Challenge

M87 contains an observing challenge for experienced observers. Several observers report that the jet emanating from the core of this galaxy, famous in photographs, can be observed visually in telescopes possibly as small as 10" on a night of excellent seeing from a dark site (according to Jay Reynolds Freeman).

Look for a short streak of light (between 1' and 5' in length) emanating from the core, slightly brighter than the surrounding haze.  The most important factor in observing this feature appears to be the seeing, so wait for a good night when the stars are very steady. Try to observe M87 as high in the sky as possible. Use as much magnification as the conditions will permit. When trying on different nights, note the visibility of the stellar core--this is a good indicator of the quality of the night and the suitability of a particular eyepiece. Once you have settled down, be patient. Take some time to take in all the detail you can. Try averted vision and wait for moments of really good seeing. If you see something that looks like a streak, take some time to confirm your observation until you are convinced. Record the direction you see for the jet in a drawing and check your observation against the image at the Adventures in Deep Space site, where you can also find more information regarding this interesting new challenge. This image has north up and east to the left, and measures about 10' x 12'.

I had a look for the jet myself with my 18-inch Dob in late April, but the seeing was quite poor. I had the impression of something there, which is encouraging. Although only a vague impression, I was surprised to discover that the orientation I "observed" matched that of the picture. I tried again in early May when the seeing was better. This night the stellar core was much more obvious. I was quite surprised at the remarkable difference in appearance! My 4.8mm Nagler (425x) gave a nice view but it was just a bit soft as compared to my 12.4 mm Suppler Plossl (165x), which showed the stellar core much more clearly. The best view came with the Plossl and a 2X barlow (329X).

With the seeing blowing up at regular intervals it took some patience to see the feature I was looking for. At first I only had brief glimpses of a tiny streak of light, just a bit brighter than the surrounding haze of the galaxy. I couldn't be sure that I was seeing it at all, although the direction of this streak seemed consistent (with one notable exception). Eventually the seeing steadied for longer periods and I became convinced that I was indeed seeing a tiny streak, emanating from the core of M87 in a consistent direction. At times, the streak appeared to have knots in it, but I can't say if this was real or an illusion.

I'm convinced that the jet will be much more obvious when the seeing is better and I plan to have a try again on the next good night. Are you game? Go for it!

Markarian's Chain

One of the main features of downtown Virgo is Markarian's chain. This chain of galaxies stretches from NGC 4388 in the south to NGC 4477, through NGC 4459, up to M88. The DSS image below, from SkyView, shows a 2.5o x 2.5o region containing the chain. The orientation is the same as the chart above.

Starting with good old M86, which is a rather non-descript galaxy as ellipticals often are, look for NGC 4402 to the north. This 12.6-magnitude edge-on spiral galaxy appears as a faint, highly elongated smudge with no clear central brightening. To my eye, it looked mottled, perhaps revealing the presence of detail just beyond my ability to discern.

To the south lies NGC 4388, another edge-on spiral (11.8 mag) that looks very similar to NGC 4402.

To the northwest lie a pair of galaxies called The Eyes, NGC 4438 and 4435. NGC 4435 is the fainter of the two and this barred lenticular appears as a smooth round smudge. NGC 4438 is a more interesting edge-on spiral. In telescopes larger than 16", look for the faint irregular outer limbs to the southwest and northeast (see photo). The northeast limb appeared more easily to me in my 18-inch Dob.


For reasons that are not as yet clear, galaxies group together in clusters. Our own galaxy, the Milky Way, belongs to one such cluster called the local group. As clusters go, the local group is rather small with only about 30 members spread over about 3 million light years.

The Virgo cluster is the nearest moderately rich group. It contains thousands of members within an area of about 5 million light years.

The Coma cluster is even larger, containing tens of thousands of galaxies within a diameter of 10 million light years. It has been estimated that the total mass is over a million billion stars like the sun. The Coma cluster lies about 300 million light years distant, some six times farther away than the Virgo cluster.

At the centers of large clusters we find giant elliptical galaxies such as M87. These are elliptical galaxies that are much larger and more massive than most. The central regions are also unusually devoid of spiral galaxies. This may be an important clue to the evolution of galaxies. Computer models predict that the collisions between galaxies can disrupt and destroy the arms of a normal spiral galaxy, leaving behind something that looks more like an elliptical. There is no more likely place for galaxies to collide than in the rich central regions of large clusters, so it seems likely that billions of years of collisions in these regions has yielded few spiral galaxies and built one or more giant ellipticals.

For more on observing the Virgo Cluster see Mastering the Virgo Cluster (Sky & Telescope, May 1994, pg. 42) and the Adventures in Deep Space web site.

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