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Cosmic Challenge: The Orion Galaxy


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Cosmic Challenge:

The Orion Galaxy

February 2018

Phil Harrington

 

This month's suggested aperture range

6- to 9.25-inch

(15-23cm)  telescopes

Target

Type

RA

DEC

Constellation

Magnitude

Size

NGC 1924

Galaxy

05 28 01.9

-05 18 37

Orion

13

1.5'x1.1'

 

You've heard of the Andromeda Galaxy and the Orion Nebula, but how about the Orion Galaxy?  Probably not.  But would you believe the New General Catalog lists 21 galaxies in Orion, and the Index Catalog adds another 9? That's a pretty respectable tally. Of those 30 Orion galaxies, I find this month's challenge particularly intriguing because it lies so close to everyone's favorite winter deep-sky object, M42. Yet, I am sure that very few observers have seen it.

Above: Winter star map.

Credit: Map adapted from Star Watch by Phil Harrington

 

Above: Finder chart for this month's Cosmic Challenge.  

Credit: Chart adapted from Cosmic Challenge by Phil Harrington
Click on the chart to open a printable PDF version in a new window

NGC 1924, a barred spiral galaxy, was discovered in 1785 by William Herschel using his 18.7-inch (47.5cm) reflector, undoubtedly on an evening when he too was admiring the Orion Nebula.  And why not?  After all, M42 lies less than 2° to the east.  That's pretty good company to keep, but at the same time, it can also be a curse, since the Orion Nebula can be pretty distracting. 

Finding NGC 1924 is easy enough by starting at M42 and scanning due west.  Some 1½° into your scan, you will come to a diagonal path of three 8th-and 9th-magnitude field stars oriented northwest-southeast from one another.  NGC 1924 lies along the path, like a distant galactic steppingstone equally spaced between two of those Milky Way suns.

When summarizing its appearance for his New General Catalog, John Dreyer described it as "very faint, pretty large, irregularly round, stars nearby."  My 8-inch (20.3cm) Newtonian shows NGC 1924 as a faint, oval disk accented by a stellar nucleus.  It lies between two 8th-magnitude stars set amidst a sparkling field of fainter stardust.

Larger apertures bring out additional subtle details.  Through my 18-inch (45.7cm) reflector, the galaxy reveals a brighter outer edge and a star-like central core, closely mimicking the look of a planetary nebula.  Add in the spectacular surroundings and how they add a faux-3D effect, and the beauty of this little treasure really comes through.  It's a challenge that you are sure to return to time and again as you further explore its more affluent neighbor.

Above: NGC 1924 as sketched through the author's 8-inch (20.3cm) reflector.

 

 

 

And what of the remaining NGC and IC galaxies within Orion?  Here's the list.

 

Designation

Coordinates

RA h m s

Dec ° ' "

Magnitude

Size

IC 392

RA 04 46 25.8 Dec +03 30 20

13

1.4'x0.9'

NGC 1661

RA 04 47 07.7 Dec -02 03 18

13

1.4’x0.9’

IC 395

RA 04 49 34.0 Dec +00 15 10

13

1.3’x1.0’

NGC 1670

RA 04 49 42.6 Dec -02 45 36

13

1.3’x0.7’

NGC 1678

RA 04 51 35.4 Dec -02 37 22

13

1.1’x0.8’

NGC 1682

RA 04 52 19.7 Dec -03 06 19

14

0.9’x0.9’

NGC 1683

RA 04 52 17.5 Dec -03 01 27

15

1.0’x0.4’

NGC 1684

RA 04 52 31.1 Dec -03 06 20

12

2.2’x1.7’

NGC 1685

RA 04 52 34.2 Dec -02 56 59

14

1.3’x0.9’

NGC 1690

RA 04 54 19.3 Dec +01 38 26

14

1.0’x1.0’

NGC 1691

RA 04 54 38.3 Dec +03 16 04

12

2.3’x1.8’

NGC 1709

RA 04 58 44.1 Dec -00 28 42

14

1.0’x0.7’

NGC 1713

RA 04 58 54.6 Dec -00 29 21

13

2.7’x1.8’

NGC 1719

RA 04 59 34.5 Dec -00 15 38

14

1.1’x0.3’

NGC 1729

RA 05 00 15.6 Dec -03 21 11

13

1.7’x1.4’

IC 2112

RA 05 00 30.2 Dec +04 23 11

14

0.5'x0.2'

NGC 1740

RA 05 01 54.7 Dec -03 17 45

13

1.5’x1.2’

NGC 1753

RA 05 02 32.2 Dec -03 20 41

15

1.4’x0.6’

NGC 1762

RA 05 03 37.0 Dec +01 34 24

13

1.7’x1.1’

NGC 1819

RA 05 11 46.0 Dec +05 12 03

13

1.3’x1.0’

IC 404

RA 05 13 19.6 Dec +09 45 1

15

0.8'x0.6'

NGC 1843

RA 05 14 06.1 Dec -10 37 36

13

2.1’x1.7’

IC 409

RA 05 19 33.7 Dec +03 19 04

14

1.3'x1.0'

NGC 1875

RA 05 21 45.7 Dec +06 41 20

14

0.8’x0.7’

IC 414

RA 05 21 55.0 Dec +03 20 31

14

0.7'x0.4'

IC 412

RA 05 21 56.8 Dec +03 29 10

14

1.4'x0.7'

IC 413

RA 05 21 58.8 Dec +03 28 55

14

1.0’x1.0’

NGC 1924

RA 05 28 01.9

Dec -05 18 37

13

1.5'x1.1'

IC 421

RA 05 32 08.5 Dec -07 55 05

14

3.3'x3.2'

NGC 2110

RA 05 52 11.2 Dec -07 27 23

13

1.7’x1.2’

NGC 2119

RA 05 57 26.9 Dec +11 56 56

14

1.2’x1.0’

 

Above: Orion's NGC and IC galaxies

 

Notice from the chart above how most are clustered along the constellation's west-southwest border.  That's not surprising, since that area is farthest from the obscuring dust clouds that permeate Orion.  Further west, the river Eridanus overflows its banks with a flood of faint galaxies.

Be aware that many of Orion's galaxies are below the cutoff threshold of this column's self-imposed aperture class.  But give them a go anyway.

I'd especially draw your attention to two galaxy groups.  The first is a trio formed by of IC 412, 413, and 414, with a fourth, IC 409, waiting in the wings.  You'll find them 3° south-southwest of Bellatrix [Gamma (γ) Orionis].

The second group is a tight pact in the constellation's southwestern corner.  NGC 1682, 1683, 1684, and 1685 are so closely spaced that at the chart's scale here, they nearly overlap one another.  Notice that the brightest of the four is 12th magnitude, with the others plummeting as low as 15th magnitude.  That's a tough test for even the largest amateur telescopes.

Be sure to share your results with the rest of us by posting in this article's discussion forum.

Have a favorite challenge object of your own?  I'd love to hear about it, as well as how you did with this month's test.  Contact me through my web site or post to this month'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 his web site at www.philharrington.net to learn more.

Phil Harrington's Cosmic Challenge is copyright 2018 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.

 


  • rolo and okiestarman56 like this


12 Comments

Thank you, Phil. I never think to scan over that way.

    • PhilH likes this

Hey, that's a great article Phil. Definitely enough there to get me out on a clear cold night to try and do an Orion galaxy sweep. Just like trading cards when I was a kid...I want to collect 'em all. As always, most of your observing reports are unusual in the sense that they cover many things I've never seen before and I do appreciate that. Thanks!

    • PhilH and Raleigh like this
Photo
John Gauvreau
Feb 03 2018 12:13 PM

Very cool, Phil!  I look forward to exploring those.  Thanks!

    • PhilH likes this
Photo
John O'Hara
Feb 03 2018 05:20 PM

Though I have your book, I've never went for this one.  If these lake effect clouds go away when the moon's not up, I'll give it a try with my 7" reflector.  

    • PhilH likes this
Photo
Dave Mitsky
Feb 04 2018 06:30 PM
There's an image of NGC 1924 posted at http://www.kopernik....chive/n1924.htm

Dave Mitsky

Thanx, Phil; I'll haul that list out to the scopes. Nice and convenient all in that one piece of sky. Galaxies are all over the place, even where we generally don't think of looking for them.  Tom

I wasn't crazy!!!

Last year while scanning Orion at a dark site, I noticed a smudge there .. I had to use averted vision, but there was something ... I mentioned that to some fellow guys, they gave me the "you just got crazy" eye...

NOW I know what I was looking at.

Phew!!!

From now, on, I can re-see that object (NGC1924) with total confidence ...

I shared the article with another CN member and we are going to have a ball at out next star party in a Bortle 3 sky. I have already found NGC 1924 with my 8SE and I will be using my CPC 1100 at the star party along with a AT 130EDT refractor.... This is going to be nice

Yep, looking at "that thing in Orion, at its west side" showed me my (averted and technique) vision has improved a lot since I started with my first telescope :)

Enjoy the SP!!!

I m signing up for RTMC in May, like Woodstock ... but with telescopes :lol:

I took  a single  8 minute exposure of ngc  1924 with my 10" lx200 classic, and you guys have a lot better eyes then I do.  What a faint target!   You have my respect.

Phil:

 

Thanks for the heads up an NGC1924. I'd never seen it before. 

 

While i was looking at Sky Safari to locate 1924, I noticed a small group of galaxies about 5 degrees at 300 degrees from 1924, PGC 16893, PGC16895 and UGC102. They're listed at magnitude 14.5-14.8. My skies aren't the darkest to the south,  there's a prison across the border in Mexico but i was able see them in the 22 inch. 

 

Now you've got me interested, I'll be looking for more..

 

Jon

Photo
seanmcclain
Feb 15 2018 06:15 AM

There was a hole in the clouds in upstate NY last night, so I gave the challenge a try with my 8"reflector. I was unsuccessful, but sure enjoyed the effort! I'll keep trying, and when I get another hole in the clouds I may try to filter some of the sky glow to see if that helps.



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