Object of the Week December 22, 2019 - NGC 2403

[Dragan]

NGC 2403
UGC 3918
PGC 21396

Galaxy (SAB(s)cd)
Camelopardalis

RA 07 36 52.40
DEC +65 36 9.3

Mag: 8.93
Size: 18’x11’

A member of the large M81 group of galaxies, NGC 2403 is a beautiful, slightly inclined face-on spiral galaxy located in the northeast corner of Camelopardalis. Classified as an intermediate spiral, NGC 2403 very much resembles M33 in Triangulum in morphology. NGC 2403 was discovered in 1788 by William Herschel using his 18.7-inch speculum mirrored telescope.


Visually, NGC 2403 is visible in all manner of telescope apertures. Smaller telescopes under relatively decent skies show a mottled, non-descript glow whereas scopes in the 16” and larger realm tend to reveal the object’s 2 prominent arms as well as an abundance of HII regions throughout. NGC 2403, again much like M33, has a prominent HII region that should be looked for by observers with larger scopes. NGC 2404 is a massive HII region east of NGC 2403’s center that makes a great secondary target.


As always, give it a go!


Finally, I wish everyone a very happy holiday season and a happy new year! See you in 2020!

3748
Pugh

3749
ESA/Filippenko/Challis

3750
ESA/Filippenko/Challis

[lamperti]

Saw this with a 10" back in 1987 at 47x: "Star hop is easy. Fairly bright and elongated. Bridge between two stars. Appears granular." Now that I see the images posted, the 'granularity' was probably the extensive H II regions described. Worth another look with more aperture and magnification.

[Raul Leon]

Hi here's my observation from 1/18/2018: ngc 2403 galaxy in Camelopardalis ; mag: 8.5 ;bright, large and elongated ; bright core with many HII regions visible, the brightest being ngc 2404 East of the core. Impressive with a mottled texture throughout the galaxy. Some stars superimposed on galaxy. I used a 10mm Ethos at 158x magnification with my 14.5 Starstructure Dob f/ 4.33751

[Clear Skies]

Three observations for NGC2403, two of which contain a description for the HII region NGC2404.


4 November 2018 - French Ardennes, SQM 21.10, 14" SCT @ 168x/29'

The galaxy NGC2403 is a large, quite bright, NW-SE elongated glow, brighter in a large, round central part that is slightly NW of the middle. Has irregular structure that is clear when using AV. With AV the galaxy is flattened on the SW side on a line from NW to SE.
The HII region NGC2404 is a round, almost detached patch (resembles a satellite galaxy), gradually brighter in the middle. To the SSE is a mag. 10 star.

Rated the galaxy 7/10, the HII region 5/10.


7 February 2018 - northern Germany, SQM 21.57, 14" SCT @ 168x/29'

A large, oval, bright glow with irregular structure, elongated SE to NW.
On the ESE edge is a mag. 10.5 star with a mag. 14 star to its SW. WSW of the center is mag. 13 star with a mag. 11 to its WSW, just detached from the galaxy.
To the NNW of the mag. 10.5 star on the ESE edge is a small, round patch that resembles an elliptical galaxy (HII region NGC2404) with a SE-NW elongated, darker part of the galaxy to its WSW.

Rated the galaxy 6/10, the HII region 5/10.


10 February 2008 - the Netherlands, 8" SCT @ 113x/34'

A large, hazy, north-south elongated patch. No nucleus visible but it does appear mottled.
Directly WNW and ESE are mag. 9 stars, directly west of the center is a mag. 10 star.

Rated the galaxy 6/10.

[Bertrand Laville]

Hi All,

Here are the 18 HII regions I could see with my 25 inches Obsession, in a rather good sky of southern alps (NELM 6.8, SQML 21.73)
Report here: http://www.deepsky-drawings.com/ngc-2403-t635-vs-t1-20m/dsdlang/fr
It is interesting to know that I observed the galaxy some months ago in a big 48 scope, but in a not so good sky (SQM 21.2), and I saw less HII regions.

Clear skies
Bertrand
http://www.deepsky-drawings.com/


3752


3753

[Uwe Glahn]

Found an old observation and sketch with 16-inch.

sketch: 16", 225x, NELM 6m5+
3764

A later observation with an 24-inch shows much more HII regions similar to Bertrands sketch.