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Cosmic Challenge: NGC 2403


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Cosmic Challenge:
NGC 2403

 

March 2024

 

 

Phil Harrington

 

 

This month's suggested aperture range:

7x to 10x Binoculars

 

 

 

Target

Type

RA

DEC

Constellation

Magnitude

Size

NGC 2403

Spiral
Galaxy

07h 36.9m

+65° 36.2

Camelopardalis

8.4

22'x12'

 

Hovering above the northeastern horizon at this time of year is the obscure constellation Camelopardalis the Giraffe. Though the human eye alone reveals little more than a void populated by a scattering of 4th-magnitude and fainter stars, binoculars begin to unleash some of the beast's latent wonders. One of the Giraffe's few hidden treasures that is visible through binoculars is NGC 2403, a spectacular spiral galaxy tilted nearly face-on to our perspective.

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.

 

NGC 2403 is situated approximately 10 million light years away. Images reveal that its spiral arms containing many star clusters and glowing regions of ionized hydrogen, both telltale signs of ongoing stellar birth and evolution. NGC 2403 stands as a distant, though prominent member of the M81 galaxy group, which is centered 14° to the east in neighboring Ursa Major.

 

William Herschel discovered NGC 2403 back in 1788. That makes it one of the brightest galaxies in the northern celestial hemisphere that was missed by Charles Messier and and his contemporary, Pierre Méchain. Although their omission may have been due to the galaxy's sparse surroundings, NGC 2403 is actually not that hard to find.

 

Here's how I go about it through binoculars. Begin at Muscida [Omicron (ο) Ursae Majoris], the nose of the Great Bear. From there, slip about 5° northwest to 6th-magnitude 51 Camelopardalis. NGC 2403 lies in wait just 1° further to the west.

 

Recently I revisited NGC 2403 through my 10x50 binoculars. I could just make out its tiny, oval glow against the background sky from my suburban backyard here on Long Island. Under darker skies, however, it has come through as a dim splotch in 7x35 binoculars, while the 10x50s uncovered the galaxy's round, diffuse core centered in an elongated halo, shown in rendering below.  As always, there is no substitute for a dark sky.

 

NGC 2403 imaged by CN'er tbhausen using a ZWO Seestar S50. The image is composed from 90 subframes @ 10 seconds each. Image scale compares to the view through 15x and 16x binoculars.

 

NGC 2403 imaged by CN'er TomC_RR with a Canon T7 DSLR on an AstroTech 130EDT with 0.8 reducer/flattener and a 2x Powermate, on an EQ6R-Pro mount. Note the knots within the spiral arms.

 

 

Above:  NGC 2403 as seen through the author's 10x50 binoculars.

 

Great detail in this striking broad-armed spiral galaxy can be glimpsed when viewed through moderate-size amateur telescopes.  A 10-inch (25-cm) instrument hints at spiral-arm structure toward the galaxy's western edge, a trait that is more readily confirmed in 12-inch (30.5-cm) and larger telescopes. These same scopes also reveal a very faint nebulous "star" within one of the spiral arms. Higher power confirms that this is not a star at all but rather a huge Hydrogen-II region separately cataloged as NGC 2404. Photographs reveal this is only the brightest of many H-II regions and clusters of stars sprinkled across the galaxy.

 

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 is a contributing editor to Astronomy magazine and is the author of 9 books on astronomy.  Visit www.philharrington.net to learn more.

Phil Harrington's Cosmic Challenge is copyright 2024 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.

 


  • Special Ed, John O'Hara, warddl and 1 other like this


12 Comments

Photo
Urban Observer
Mar 04 2024 12:49 PM

This is a most excellent post! I absolutely love all the different views provided - Inspiring!  A quintessential monthly challenge - Perfect!

Clear skies!

    • CollinofAlabama and PhilH like this
Photo
Dave Mitsky
Mar 04 2024 05:24 PM

I've observed NGC 2403 quite a few times but never using binoculars.  I'll have to give it a go with my Canon 15x50 IS the next clear night.

 

I happened to image NGC 2403 from my light-polluted red zone front yard on the morning of January 12th with my Seestar S50.  The exposure was for 11 minutes.


Attached Thumbnails

  • Attached Image: NGC 2403 Astro Cooker 1-12-24 AM Seestar S50 IMG_3956 Processed 2 Cropped Resized 1000.jpg
    • CollinofAlabama, Urban Observer and micromaxcomputer like this

Hovering above the northeastern horizon at this time of year is the obscure constellation Camelopardalis the Giraffe. Though the human eye alone reveals little more than a void populated by a scattering of 4th-magnitude and fainter stars, binoculars begin to unleash some of the beast's latent wonders. One of the Giraffe's few hidden treasures that is visible through binoculars is NGC 2403, a spectacular spiral galaxy tilted nearly face-on to our perspective.

Click here to view the article

From my log--a mix of 8" and 12.5" observations in about 21.4 skies.

"Wow! Large, bright, spiral, stellar core, diffuse outer edges, 45° angle?, oval visually, core appears off-ctr, internal mottling, best magnification 200-230x."

Oh, my notes header says "also seen in 50mm finder scope".

    • Dave Mitsky, CollinofAlabama, Jon Isaacs and 1 other like this

First time I saw NGC 2403 was also my first super nova if I remember correctly. It was SN 2004dj. I remember it because I also had to carry then assemble my f/6 11.5” truss dob to one of the upper levels of my terraced garden so I could see over the 50 metre cedars on the N side of the house. My observation is pretty much what Don wrote except it also had an extra dot! It’s quite a beautiful galaxy. It even shows its mottled characteristics with my 6” dob.

 

Bill

    • CollinofAlabama likes this
Photo
Dave Mitsky
Mar 05 2024 02:54 PM

First time I saw NGC 2403 was also my first super nova if I remember correctly. It was SN 2004dj. I remember it because I also had to carry then assemble my f/6 11.5” truss dob to one of the upper levels of my terraced garden so I could see over the 50 metre cedars on the N side of the house. My observation is pretty much what Don wrote except it also had an extra dot! It’s quite a beautiful galaxy. It even shows its mottled characteristics with my 6” dob.

 

Bill

SN 2004dj was a Type IIP supernova that reached a peak brightness of magnitude 11.2.

 

https://www.rocheste...4/sn2004dj.html

    • CollinofAlabama likes this
Photo
Dave Mitsky
Mar 08 2024 10:26 PM

I was at the orange zone Naylor Observatory last night.  While the transparency was rather good early in the night, it worsened as the night progressed.  After doing some binocular and telescopic observing and imaging with my Seestar S50, I attempted to view NGC 2403 with my Canon 15x50 IS.  It was a marginal sighting at best given the conditions, but I believe that I saw NGC 2403.
 

    • CollinofAlabama likes this
Photo
Alex Swartzinski
Mar 11 2024 09:41 AM

I had a great observing session last night under dark and transparent skies. NGC 2403 was obvious as a soft glow between field stars in my 9x50. 

 

Switching to the 15" dob my notes read:

 

"Mottled core features a detached inner halo with a stellar like appearance. A weak spiral arm is traced with averted vision as it bends to the south between field stars. The galaxy features an uneven surface brightness and additional spiral arms are suspected based on the dark gaps between them. Best at 250x. 

 

Here's the confirmed arm with Tom's picture:

 

Attached Image: photo_TomC_RR.jpg

 

This was one of my favorite galaxies of the night! 

    • CollinofAlabama and 112aug like this
Photo
Dave Mitsky
Mar 17 2024 11:08 PM

Despite the bright moonlight, I decided to see if I could detect NGC 2403 before leaving the Naylor Observatory tonight, which I'm about to do.  I placed a chair in the Moon's shadow and carefully surveyed the area where NGC 2403 resides with my Canon 15x50 IS and I'm fairly certain that I did indeed see it.

    • CollinofAlabama likes this

Thanks Phil!

 

I had my 15x70s with me for 12P/Pons-Brooks, but I went for NGC 2403 last night in my 10-inch GSO dob from what is supposed to be a 21.05 mpsas site (per Lorenz's 2022 overlay) or around Bortle 4 or 5, with a nice transparent sky but miserable 3/10 seeing. 

 

My notes:

 

It was an easy dial-up with my azimuth circle and digital angle gauge using the 30 mm APM UFF 2-inch eyepiece. Even in that low power (42x) I can see quite a bit of indeterminate swirly detail in the galaxy itself. Two 10th magnitude stars on either end of it, but it actually extends beyond those two stars so they're kind of annoying, as with any brighter star superimposed on a fainter galaxy. The center of the Galaxy is almost halfway between the two stars, which are oriented east-west. The galaxy is offset slightly to the north of them and it's elongated southeast-northwest.

 

In the Baader Hyperion 8-24 mm zoom eyepiece, at the second click (96x), I could see there's a dimmer star of 12.5 mag that's not quite in a line between the two stars and about 40% of the distance from the westernmost and slightly offset to the north. The center of the galaxy is just a little north of that. I could see some good swirling action in the galaxy. I can also get glimpses of the nebula (NGC 2404) in there, but it only comes out about 10% of the time maybe even less than that. I can hold that nebula about 80% of the time in 156x (max for the Hyperion in my scope). But I think around 130x is a little better. 

 

I just picked up a Svbony SV135 7-21 mm zoom for outreach events, and got a comparable view to the Hyperion, maybe a shade less contrast and a bit narrower field of view. The best view in the Svbony is probably zoomed all the way in at 7 mm (179x). NGC 2404 comes out maybe even a little better, although the galaxy itself is not quite as bright as in the Hyperion, probably due to the higher max power.

    • CollinofAlabama likes this
Photo
Dave Mitsky
Apr 09 2024 09:16 AM

I observed NGC 2403 from the TSP 2024 Total Solar Eclipse and Star Party observing field on Friday and Sunday nights using my Canon 15x50 IS and on Sunday night using my 101mm Tele Vue refractor.  The highest SQM-L reading I obtained was 20.9 mpsas on Sunday night.

I observed NGC 2403 from the TSP 2024 Total Solar Eclipse and Star Party observing field on Friday and Sunday nights using my Canon 15x50 IS and on Sunday night using my 101mm Tele Vue refractor.  The highest SQM-L reading I obtained was 20.9 mpsas on Sunday night.

20.9 was the brightest, or darkest?

Photo
Dave Mitsky
Today, 02:01 AM

20.9 was the brightest, or darkest?

That was the best reading, in the darkest part of the sky, that I got during the event.  Unfortunately, the beautifully crystal-clear days and nights occurred before and after the star party.



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