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Cosmic Challenge: Leo Trio 2


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Cosmic Challenge:
Leo Trio 2

 

April 2020

 

Phil Harrington

 

This month's suggested
aperture range
:

6- to 9.25-inch
(15-24cm)
telescopes

 

 

 

 

Target

Type

R.A.

Dec.

Constellation

Magnitude

Size

Leo Trio 2

Galaxy
group

09h 43.2m 

+31° 55.7'

Leo

see table below

~11'

 

 

You have undoubtedly heard of the Leo Trio, made up of M65, M66, and NGC 3628. But how about the Leo Trio 2? The Leo Trio 2 are tucked snuggly into the constellation's northernmost quadrant, some 7° north of the Leo "sickle."

 

Above: Evening star map. Credit: Map adapted from Star Watch by Phil Harrington

Above: Finder chart for this month's Cosmic Challenge.
Click on the chart to open a printable PDF version.

 

 

Begin at Rasalas [Mu (μ) Leonis], the orangish star at the pointy northern tip of Leo's sickle-shaped mane. Looking through your finderscope, scan about 5° to the northwest for the 6th-magnitude 15 Leonis. Look for a 7th-magnitude companion star just 13' to its northwest, which helps 15 stand out from the crowd. Can you also spot a fainter, slightly orangish point (SAO 61633) about 1¼° further to the north-northwest? If so, hop to it through your finder, and then switch to your telescope, widest-field eyepiece in place. Offset that star toward the southwestern edge of the eyepiece field until a rectangle of four 9th- and 10th-magnitude stars is centered in the field. NGC 2964, the leader of this small galactic pack, is the same distance northeast of the rectangle as the orangish reference star is to its southwest.

 

The table below lists the three members of the Leo Trip 2.

Members of Leo Trio 2

Target

Type

RA

DEC

Magnitude

Size

NGC 2964

Galaxy

09 42.9

+31 50.8

12.0b

2.9'x1.5'

NGC 2968

Galaxy

09 43.2

+31 55.7

12.8b

2.2'x1.5'

NGC 2970

Galaxy

09 43.5

+31 58.6

14.4b

0.6'x0.4'

 

Even though it is the brightest of the three, NGC 2964 is still a dim target in 6- to 9.25-inch scopes. Photographs reveal it to be a spiral galaxy inclined to our view some 50°. At 112x through my 8-inch (20cm) reflector, NGC 2964 shows off a pale, oval glow elongated approximately east-west and surrounding a very faint, round core. I usually need averted vision to see the full span of the oval halo, but found little benefit from increasing the magnification. It lies some 60 million light years away and measures about 60,000 light years across. Studies show that a transparent bridge of hydrogen extends from NGC 2964 to our next target found not quite 6 arc-minutes to its northeast.

 

Above:  Leo Trio 2 as seen through the author's 8-inch (20cm) reflector.

 

Above: Image of the Leo Trio 2 pack. (North is up)

Credit: Donald Pelletier / Wikimedia Commons

 

 

NGC 2968 is a tougher catch, although it is visible through my 8-inch from under suburban skies by using averted vision. My records recall a small, very dim, featureless oval glow oriented approximately northeast-southwest. The lack of any distinguishable centralized nucleus adds to its obscurity. Although photographs record it as nearly as large as NGC 2964, it strikes my eye as perhaps only half the size. Those same photos reveal that NGC 2968, an irregular galaxy, has a pair of odd, dark, S-shaped lanes protruding from the galactic center and extending along the galaxy's major axis. Although I can see no sign of them even in my 18-inch reflector, I wonder if these lanes might be visible through larger amateur scopes. And that hydrogen bridge connecting NGC 2964 and 2968? According to a 2016 paper published in The Astronomical Journal entitled Global Properties of Neutral Hydrogen in Compact Groups, it actually extends farther still, toward our final quest.

 

The third and faintest member of this galactic trilogy is NGC 2970, just 5' northeast of NGC 2968. It shines a magnitude dimmer still, and so poses a real test for medium apertures. My 8-inch can't pull it out from my light-polluted backyard but was able to offer up a very dim glimmer from darker, rural skies. Even under the best conditions, it looks just like a very faint star. Don't feel too badly if you can't nab this last galaxy, however. William Herschel missed it as well when he discovered NGC 2964 and 2968 using an 18.7-inch reflector in 1785. It took the more youthful eyes of his son, John, viewing through the same aperture in 1828 to spot it.

 

Finally, I should point out that calling this the "Leo Trio 2" is selling the group a little short.  There are plenty of backup members, as well.  In reality, NGC 2964 is believed to be gravitationally associated with no fewer than three more galaxies in the general area: NGC 3003, NGC 3011, NGC 3021. And that's not all.  Other nearby galaxies include NGC 3118, NGC 3067, NGC 3032, and NGC 3026. This trio, it turns out, is a galactic dectet.

 

Good luck with this month's Cosmic Challenge! And be sure to post your results in this column's discussion forum.

 

Until next month, remember that half of the fun is the thrill of the chase.  Game on!



About the Author:

Phil Harrington writes the monthly Binocular Universe column in Astronomy magazine and is the author of 9 books on astronomy.  Visit www.philharrington.net to learn more.

 

A revised, second printing of Cosmic Challenge: The Ultimate Observing List for Amateurs is now available with updated data tables and charts for finding various solar system objects, such as Pluto and Vesta, as well as improved renditions of the many eyepiece sketches that accompany each of the 187 challenges encompassing more than 500 individual objects.  The book is available from Amazon.com.  

Phil Harrington's Cosmic Challenge is copyright 2020 by Philip S. Harrington.  All rights reserved.  No reproduction, in whole or in part, beyond single copies for use by an individual, is permitted without written permission of the copyright holder.

 


  • random, okiestarman56, John O'Hara and 2 others like this


13 Comments

Ah the Leo Trio, one of my favorites for many, many years. Always enjoyable to look at, even with a small telescope. Leo Trio 2 though was unknown to me until I acquired a larger telescope and started going to darker skies. Still a nice catch by any measure.

 

Taras

    • PhilH likes this

Finally got a clear night at the edge of the Las Vegas Valley.  Through a 16" SCT, NGC 2964 and 2968 were fairly easy from my somewhat light-polluted backyard.  NGC 2970 was tougher, but I was able to locate it using field stars as a reference.  There are two stars that form an equilateral triangle with NGC 2968 and a right-angle isosceles triangle with NGC 2970.  At 270x, NGC 2970 was visible using averted vision as a small hazy patch.  The best (as in least difficult) view was at 400x, with Leo Trio 2 almost overhead.

    • PhilH, Sasa and dagadget like this

As always, nice and interesting writing, Phil. I enjoyed reading it.

 

With my small refractors I have no chance to see the smallest member of the trio, NGC 2970. So far, I succeeded to glimpse NGC 2964 through 82mm refractor from our light polluted backyard. It was invisible at 42x, I had to increase the power to 62x. I saw at this magnification occasionally a small misty patch elongated in E-W direction. It was practically gone at 104x. I did not notice NGC 2968 that night (although I was not really looking for it).

    • PhilH and optinuke like this
Photo
Astrobill57
Apr 20 2020 08:02 AM

Thanks for pointing out this nice grouping.  I was able to observe all three fairly easily last night under rare triple unicorn conditions here in NE Wisconsin (clear, calm, execellent transparancy).  

    • PhilH likes this

Great challenge, Phil!

 

  I gave it a go this evening from my "decent suburban" skies (30 minutes south of DC.)  Was able to snag two with my 12.5" dob, and MAYBE the third.  I'd call it "active averted imagination."  However, it was pretty soupy outside, so going to try it on a drier night.  Thanks for a great evening's project!

    • PhilH likes this

Phil: Thanks again for another cosmic challenge.

 

Sheltering in place and a very cloudy 2020 has severely reduced my time at our place in the high desert but there's few days here where I am out taking care of the place and the skies are clear.

 

Last night, and had the 22 inch out, observed until about 11 pm, laid down to rest.  I was up again about 2:00 am, went out today observe.

 

I remembered this challenge so I looked it up on Cloudy Nights, entered NGC2964 into SkySafari.. unfortunately they were in the west and dipping into the light dome from San Diego but I was able to see the three of them without much difficulty.  

 

I also tried with my 4 inch but I could only see one cleanly and maybe a second one.

 

Tonight, I will catch them in the early evening when they're better positioned .

 

Jon

    • Dave Mitsky likes this
Photo
Dave Mitsky
Apr 23 2020 04:22 PM

I know I've observed NGC 2964 in the past.  I'm not sure about the other two galaxies.

 

As an aside, I wish people would decide just which three galaxies make up the Leo Trio and which constitute the Leo Triplet.  wink.gif

 

http://astrodoc.ca/the-leo-trio/ - Leo Trio
 

https://observing.sk...s/apr/M_65.html - Leo Trio

 

https://apod.nasa.go...d/ap190418.html - calling the 3 galaxies the Leo Trio and the Leo Triplet on the same page
 

https://cosmicpursui...ur-leo-triplet/ - Leo Triplet
 

http://www.messier.s...ore/m066gr.html - Leo Triplet

 

    • Jon Isaacs, PhilH and dagadget like this

Looking back at my notes, I see that I actually observed the trio at 10:35 pm, not long before I took my nap rather than at 2:30 am after I woke up.

 

Now you can see why I took my nap..

 

Jon

    • PhilH likes this

I know I've observed NGC 2964 in the past.  I'm not sure about the other two galaxies.

 

As an aside, I wish people would decide just which three galaxies make up the Leo Trio and which constitute the Leo Triplet.  wink.gif

I've always heard M65, M66 and NGC 3628 as the "Leo Trio," although I don't know who should be credited with coining the phrase.  I suppose if you wanted to stretch it a bit, you could also call M95, M96 and M105 a trio, as well, although they are not as close knit a group.

    • dagadget likes this
Photo
Dave Mitsky
Apr 24 2020 02:43 PM

I've always heard M65, M66 and NGC 3628 as the "Leo Trio," although I don't know who should be credited with coining the phrase.  I suppose if you wanted to stretch it a bit, you could also call M95, M96 and M105 a trio, as well, although they are not as close knit a group.

M95, M96, and M105 are part of the Leo I Group.  The Leo Trio/Triplet galaxies are sometimes included as another subgroup of the Leo I Group.

http://www.atlasofth...lgrps/leoi.html

https://en.wikipedia.../wiki/M96_Group

    • PhilH likes this

You have undoubtedly heard of the Leo Trio, made up of M65, M66, and NGC 3628. But how about the Leo Trio 2? The Leo Trio 2 are tucked snuggly into the constellation's northernmost quadrant, some 7° north of the Leo "sickle."

Click here to view the article

Very nice. I have seen all of these in my C11 scopes and in a C8 before it was sold. Not tried my 6 inch triplet refractor on them as of yet but that would make a great challenge target for it.

    • PhilH likes this

Just a quick note: The skies have been clear these last night's and I've made it a point to observe the Trio-2 each of the past 4 nights. The skies have measured 21.2-21.3.

 

No big surprises, NGC 2930 was a bit of a challenge in the 12.5 inch, in the 16 and 22 inch it was straight forward. 

 

As is usual, once I'm in an area I start looking around. NGC 3003 that Phil mentioned is 4.7' x 1.1" and worth a look. NGC 2918 and NGC 3106 are both about 300 mly distant according to SkySafari. 3106 is 0.9' x 0.2'.

 

Jon

    • Dave Mitsky likes this
Nice work there, Jon! Thanks for sharing.


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