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Contains:  NGC 2403
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NGC 2403 Galaxy in a Red Zone, 


            Douglas J Struble
NGC 2403 Galaxy in a Red Zone

NGC 2403 Galaxy in a Red Zone

Technical card

Resolution: 3395x2716

Dates:Oct. 22, 2017Jan. 28, 2018Feb. 12, 2018Feb. 13, 2018

Astrnomik CLS-CCD: 1029x60" -20C bin 1x1
Astrodon Blue Tru-Balance E-Series Gen 2: 320x60" -20C bin 1x1
Astrodon Green Tru-Balance E-Series Gen 2: 174x60" -20C bin 1x1
Astrodon Red Tru-Balance E-Series Gen 2: 133x60" -20C bin 1x1

Integration: 27.6 hours

Darks: ~50

Flats: ~50

Bias: ~250

Avg. Moon age: 16.90 days

Avg. Moon phase: 27.31%

Bortle Dark-Sky Scale: 6.00 job: 1930731

RA center: 114.217 degrees

DEC center: 65.602 degrees

Pixel scale: 0.649 arcsec/pixel

Orientation: 296.833 degrees

Field radius: 0.392 degrees

Locations: Backyard Red Zone Observatory, Taylor, MI, Michigan, United States

Data source: Backyard


I had the hardest time processing this galaxy. I was not happy at all with my initial post, so I started from scratch. It was a major challenge given my red zone along with poor transparency during my Michigan winter. So very faint.

NGC 2403 (also Caldwell 7) is an intermediate spiral galaxy in the constellation Camelopardalis. NGC 2403 is an outlying member of the M81 Group, and is approximately 8 million light-years distant. It bears a striking similarity to M33, being about 50,000 light years in diameter and containing numerous star-forming H II regions. The northern spiral arm connects it to a Star forming region NGC 2404. NGC 2403 can be observed using 10×50 binoculars.

As of late 2004, there had been two reported supernovae in the galaxy: SN 1954J, which attained a magnitude of 16 at its brightest, and SN 2004dj.

The galaxy was discovered by William Herschel in 1788. Allan Sandage detected Cepheid variables in NGC 2403 using the Hale telescope, giving it the distinction of being the first galaxy beyond the Local Group within which a Cepheid was discovered. He derived a distance of a mere 8 thousand light years. Today, it is thought to be a thousand times further away at about 8 million light years (2.5 Mpc).



Douglas J Struble
License: None (All rights reserved)

Sky plot

Sky plot


NGC 2403 Galaxy in a Red Zone, 


            Douglas J Struble