University Lowbrow Astronomers

Doug’s Deep Sky Challenge.

by Doug Scobel
Printed in Reflections: March, 2004.

Hickson 44 - Galaxy cluster in Leo

With spring fast approaching (it may actually be here by the time you read this), the thoughts of many deep sky aficionados turn to - you guessed it - galaxies!  And the constellation Leo the Lion leads the charge, with Virgo, Coma Berenices, Canes Venatici, and Ursa Major sure to follow.  But let’s take a closer look at Leo first.  Now Leo contains some well-known galaxy groups, such as the bright pair Messiers 95 and 96, and the trio M65, M66, and NGC 3628, also known as the Leo Triplet.  But there is another nice grouping of galaxies in Leo, which, while not as bright, is even easier to find, and presents up to four galaxies in the same low to medium power field!

This little group, also known as “Hickson 44,” is believed to be about 50 to 60 million light years away.  It consists of the four members NGC 3185, NGC 3187, NGC 3190, and NGC 3193, and lies almost exactly halfway between second magnitude gamma Leonis (“Algeiba”) and third magnitude zeta Leonis (“Adhafera”).  These are the second and third stars in Leo’s “sickle,” as counted from Leo’s brightest star Regulus.  This fortunate placement makes the group a sure find - just aim your scope right in the middle between those two stars, and you should be right there.

So, what should you expect to see?  Three of the galaxies, NGCs 3193, 3190, and 3185, are arranged in a more or less straight line running roughly northeast to southwest, spanning a total distance of about 20 arc minutes.  NGC 3193 is at the northeast end, followed by 3190 about five arc minutes away, and finally 3185 after another fifteen arc minutes or so.  The fourth galaxy, NGC 3187, lies about five arc minutes northwest of 3190.  All four easily fit inside the same medium power (about 100x - 150x) field, and make for a very nice view.

NGC 3193 is the brightest of the four, being listed in The Deep Sky Field Guide to Uranometria 2000 with a total visual magnitude of 10.9.  But in my 13”, it doesn’t look as bright as nearby NGC 3190, which shines a little less brightly at visual magnitude 11.2.  NGC 3193 measures 2.5 by 2.5 arc minutes, but it looks a little flattened to me.  It is listed as an elliptical galaxy, which explains the very gradual brightening towards its center.  There is an approximately 10th magnitude foreground star just touching its northern border.

NGC 3190 is listed as a peculiar spiral, extending 4.1 by 1.6 arc minutes.  It has a very elongated appearance, with a very bright core.  Again, despite having an integrated magnitude that is less than that of NGC 3193, it has a higher surface brightness and looks brighter.  I’ve found that edge-on galaxies typically look brighter to me than those that present more of a face-on profile, and these two companions are no exception.

Glowing at visual magnitude 12.2, NGC 3185 is a little more difficult to detect.  But with dimensions of 1.8 by 1.1 arc minutes, its surface brightness is still respectable at 12.8 magnitudes per arc minute.  It appears quite elongated with a somewhat brighter nucleus, while being noticeably smaller and fainter than its two brighter neighbors.

By far, NGC 3187 is the most challenging galaxy in this group to spot.  It’s listed at only magnitude 13.4, with dimensions of 3.2 by 1.4 arc minutes.  This makes its surface brightness only 14.9 magnitudes per square arc minute.  You’ll need a steady, transparent night under dark skies, good optics, and a fairly large aperture to detect this baby!  In my 13” at Lake Hudson State Recreation Area, it was a faint, elongated smudge, visible only with averted vision.

So, while this group’s members are not all that bright, it is still one of my favorites, largely because it is so easy to locate, and also because it’s a challenge to see all its members.  Perhaps the next time you are looking at some of the better known galaxies in Leo, you might want to take a little well-marked detour and check these out for yourself.  I’d like to know - what do you see?


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