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Contains:  NGC 2403
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NGC 2403, 


            Gary Imm
NGC 2403

NGC 2403

Technical card

Resolution: 2872x1831

Dates:March 26, 2019March 27, 2019March 28, 2019

Astrodon Blue 31mm Gen2 I-Series: 100x30" (gain: 139.00) -20C bin 1x1
Astrodon Green 31mm Gen2 I-Series: 100x30" (gain: 139.00) -20C bin 1x1
Astrodon Ha 31mm 5nm: 24x300" (gain: 300.00) -20C bin 1x1
Astrodon Lum 31mm Gen2 I-Series: 300x30" (gain: 139.00) -20C bin 1x1
Astrodon Red 31mm Gen2 I-Series: 100x30" (gain: 139.00) -20C bin 1x1

Integration: 7.0 hours

Avg. Moon age: 21.49 days

Avg. Moon phase: 56.83% job: 2666148

RA center: 114.199 degrees

DEC center: 65.610 degrees

Pixel scale: 0.781 arcsec/pixel

Orientation: 326.698 degrees

Field radius: 0.370 degrees

Locations: Backyard (Mag 20.8), Onalaska, Texas, United States

Data source: Backyard


This object is a beautiful spiral galaxy located only 12 million light-years away in the constellation of Camelopardalis. The galaxy is almost the size of our Milky Way, at a diameter of just under 100,000 light-years across. The galaxy is seen about 30 degrees from face-on. Numerous bright stars from our own Milky Way shine in the foreground.

This galaxy is very active, with over 100 ΗII regions visible in the spiral arms. These hydrogen regions are seen in the image as reddish glows. The largest of these regions is over 1000 light years in diameter and larger than any HII region in our galaxy. These Ha regions, along with its almost face-on view, diffuse core, and lack of distinct dust lanes in the arms, are the reasons why this galaxy is often compared to M33. M33 is smaller but significantly closer than this galaxy.

Also of note for this galaxy is that it is the location of the closest – and brightest – supernova stellar explosion discovered in many years. Amazingly, the remnant of the supernova which occurred in 2004 can still be faintly seen as a tiny dot of bluish-white light as indicated on the attached annotated image.

I have imaged this galaxy several times and I have been frustrated in not being able to obtain a crisp image of this object despite my best efforts. Reviewing multiple images of this object on the internet, I believe that the galaxy lies in a dusty area of space which obscures its finer details.



Gary Imm
License: None (All rights reserved)


  • Final
    NGC 2403, 


            Gary Imm
  • NGC 2403, 


            Gary Imm


2004 Supernova Remnant

Sky plot

Sky plot


NGC 2403, 


            Gary Imm