A Tour of the Virgo Cluster Using 15×70 Binoculars

Time: 37 minutes, 11:43pm to 12:20am CDT (04:43-05:20 UTC)
Date: June 15th – 16th, 2018
Light pollution: Bortle 3 to 4
Seeing: Alright
Transparency: Very Good
Instrument: Oberwerk 15×70 Ultra binoculars, mounted on my homemade parallelogram mount

The following is a transcript of a voice recording begun at 11:42:58pm CDT, Friday, June 15th, 2018. I was using 15×70 Oberwerk Ultra binoculars mounted on my newly-functional parallelogram binocular mount, and observing from a balcony in Jasper, AR (Bortle 3 to 4). The seeing was alright, the transparency was very good, and the moon was not up.


Transcript


“Observed the Virgo Cluster with 15×70 binoculars on my parallelogram mount.

M86 is one of the most prominent galaxies in the region, and one of the only galaxies that you’d probably pick up in a fast sweep. It appears to be pretty much round, medium small in the eyepiece. It has a moderate brightness core surrounded by a quite faint halo. The core seems not quite stellar; perhaps extended and disk-like, just a little bit, and the brightness falls off very rapidly from the core to the outer edge of the halo.

M84 lies below that, and is again, one of the more prominent galaxies in the region. It’s quite close to M86, only about half the size, but the core is of comparable brightness. This one is somewhat of a fuzzy star. The rather bright-for-a-galaxy core, medium-faint-for-a-star, is nearly stellar, well detached from the very faint fuzz which it sits in front of.

NGC 4438 lies above those two. If you draw a line from M84 to M86, then continue it about one and a third times the distance, then you come to 4438. This one is significantly fainter, and noticeably harder. Maybe a little bit larger than M84, but fainter than either M84 or M86. It seems to have two involved stars, and is elongated from about 2 o’clock to 8 o’clock in the eyepiece field of view. There seems to be one star in either end. The star in the lower left strikes me as more likely to be the core if it has one; for some reason that star seems to be more associated with the background glow than the one in the upper right, which seems to be superimposed upon that. Perhaps because the one in the upper right appears to be decentered a bit; located slightly below the axis of the galaxy.

NGC 4438, M84, and M86 create a noticeable grouping; one of the tightest groupings evident in the Virgo Cluster from my cursory pan before starting this log.

M87 resides not too far away, tugging at your view-tugging at your eyes when M84 is centered in the field of view. It’s located to the upper left, and centering it reveals that it is also quite bright, bright enough to rival M84 or perhaps slightly brighter. It has a tight, bright core which has a stellaring at the center of it, but that’s not all of the core. There’s a stellaring, then a brightish core around that, and then a bit of a faint, extended halo. Whatever halo is there is very faint. The core makes it one of the more prominently nonstellar objects, but the core is almost all there is. The fuzz around it seems to die off quickly, though in moments of clarity reaches nearly to a medium brightness star located at about 1:50 from the core.

The Siamese Twins are visible, just to the left and a little bit up from M87. A little triangular asterism is apparent; a right triangle. The top side, when you draw a straight line to the left, and continue along the length of the top side again, that’s when you come to the Siamese Twins. They’re faint, but clear at the same time, appearing as a single object, quite small, with no bright core, but a medium-faint haze that’s clear enough. It’s not difficult to hold with averted vision. A single star appears at about 11 o’clock, faint and close, about 1 diameter of the glow away.

Now, I noticed on SkyTools that another little galaxy was shown nearby, NGC 4564. That is visible; I wouldn’t have called it a galaxy, it appears purely stellar, so I’ll need to check after the fact if there is, in fact, a star right there that I’m seeing instead. It appears to the upper right of the Siamese Twins, at about 2 o’clock. It’s very faint, coming in and out with averted vision, sometimes holdable for fairly long periods of time. [long pause] Comparing it to other faint stellar objects, perhaps it is not quite stellar; it does seem slightly ill-defined, but “ill-defined” is kind of the key word with things this faint, so…

Above the Siamese Twins and NGC 4564, you come to M58. This appears as a pair with a medium- to medium-bright brightness star, with M58 being located at about 10:45. It’s a bit fainter than the star, with a– ooh! meteor! …and two satellites. lot of moving stuff in this field. Ok, with a noticeable core- I wouldn’t call it extremely condensed, though. The whole thing seems to have a brightness gradient that leads up to a small, bright core. It’s fairly small overall. The brightest part [off?] being sort of all there is; there’s not too much of a faint halo here. It’s, again, pretty much round, with maybe a faint extension towards the star.

Head to the upper right of that and you come across M60 and M59. M60 is one of the more prominent galaxies of the group; it would stand out in a sweep. It seems to have a small, sharp, moderately bright stellar core, surrounded by a respectable halo for once. The core is well-separated from the halo, but the halo does at least ramp up in brightness towards the core. It’s moderately small, and seems to have maybe a bit of an elongation left and right.

M59 is noticeably smaller and fainter, but still bright enough that it makes a nice pair with M60. Again, a somewhat tight stellar core, this time surrounded by a tight fuzz, fairly bright as far as some of these galaxies go, and a small, faint halo around that. It’s only half the size of M60, if that; perhaps more like a third.

Ok, now move to the right, and a little bit down again, backtracking a little. You’ll come to M90 and M89. M90 is moderately prominent for the group. It has a somewhat condensed core, and appears nicely detailed compared to some of these. It has a noticeable elongation. I was tempted to use the word “sharp”; it might not be entirely accurate, but that’s what came to mind, so there. It’s elongated from about, say, 1 o’clock to 7 o’clock in the eyepiece field of view. It’s located just to the right of a medium-bright star, and the brightness seems to be concentrated towards the bottom of the galaxy. It’s appreciably “fuzzy”, which is to say the brightness falls off well from the core, and the halo is pretty clear, as opposed to some of these others with a very “difficult” to “almost none” halo.

M89 is smaller, but perhaps marginally brighter. It is however significantly less obvious due to its size; being very small, with a stellar core. It’s really just one of these fuzzy stars. It’s pretty much round, probably a quarter of the size of M90. One of the things that helps with distinguishing it from a star is that there are several stars of similar magnitude scattered around, so you can see “those are sharp, this is not”; this is like a single sharp star silhouetted on an out of focus star. M89 is located at about a 7 o’clock angle from M90.

Move to the right from that and you’ll come across M91 and M88. M88 is the brighter of the two, which form a wide pair. This is one of the nicer ones, which is to say that it’s not just a stellar core; it seems to have a bit on an elongation left to right, maybe 8:30 to 2:30 in the eyepiece field of view. And I suppose I should say that the surface brightness is higher than some of these. It seems to have a bit of a core, but it’s not overly distinct, and the brightness is spread out along the elongation, fades off into the background somewhat sharply. At the left point, there is a medium-faint star, which is perhaps one ‘radius’ from the edge of the galaxy, a little bit less.

M91 is a bit dimmer, a bit smaller. Pretty much round. It gets a little bit denser in the middle, but no sharp core. It’s quite small. It seems to have a single star involved within the nebulosity, at about 7:45 from the core. It’s difficult to measure, because the galaxy is faint enough you need to use averted vision to see it. [wryly] Well, with all of these you do, but with this, it’s more extreme. The star is also quite faint.

Head back to the upper left and you’ll come across NGC 4762 and NGC 4754 on the outskirts of the cluster, which is what I’m now limited to due to it setting behind the building. This is a faint pair, but once you study it for a while, you can see it pretty clearly. Its made a little bit more difficult by the fact that it’s involved with quite a few stars. Located to the upper left of a fairly bright and wide double; if you place that double at the edge of the field then you center the galaxy pair, which is located in a structure made out of 4 or 5 medium- all the way to very-faint stars. 4762 is located midway between the two left-most and brightest stars. Another star, a fainter one, seems to pin it on the left side, and a little bit up from the axis of the galaxy. It seems to be elongated, from about 1:30 to 7:30 in the eyepiece field of view. It’s a little, faint, needle of light; certainly not a needle in the way that I always think of when I hear that, so I kind of- that’s the phrase that comes to mind, so I say it. It’s only about 2 to 2.5 times longer than it is wide. And I mentioned that faint star; it’s at the left tip, but it’s shifted slightly up, so that it’s still touching and pinning the galaxy, it’s just not quite exactly on the tip.

So that makes for quite a busy patch of sky, with those three stars and the galaxy. NGC 4754 is located to the lower right of that, at about 3:40 or so. This one is located somewhat off-center from the middle of a triangle of three of the four main “pinning” stars mentioned at the beginning. It itself appears, well, pretty much stellar. It was noticeably non-stellar enough for me to guess that that was the galaxy before checking SkyTools closely to be sure- I had glanced at the chart beforehand, but not memorized the location. However, it’s just barely nonstellar. It’s very faint, most of the time appears stellar, sometimes appears to have a little bit of fuzz. [pause] This might be another one of those where I should check and see, to make sure there isn’t a faint star in that region as well.

Ok, that might end my Virgo Cluster browsing for now. It is now 12:20am (because I just realized the timestamps will be off since I’ve been pausing it). The seeing is alright, and the transparency is very good. And I’m observing from Jasper, Arkansas [unintelligible].”


Clear Skies!
Lauren Herrington

One Response to A Tour of the Virgo Cluster Using 15×70 Binoculars

  1. Al Milano September 8, 2018 at 12:08 pm #

    Awesome stuff! Excellent work 🔭
    I’m a huge fan of binocular astronomy.

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