This is
NGC 2403 in Camelopardalis in LRGB (see the Wikipedia link for more information). It is classified as an intermediate spiral galaxy, which means it is categorized between being a barred spiral and an unbarred spiral galaxy, type SAB. It is considered part of the M81 Group, distance about 8 Mly, diameter about 50 kly. One of the numerous H II regions of this galaxy is designated as NGC 2404, being about 940 ly in diameter, and can be seen annotated using the mouse over or viewing Rev. D.
There have been two reported supernovae in NGC 2403, one is SN 1954J, the other SN 2004dj, which has been the nearest and brightest SN in the past 17 years and remains the brightest so far of the 21st Century.
Jeff Kanipe and Dennis Webb (
Annals of the Deep Sky, vol. 3, p. 43) note its similarity in form to M33, the Triangulum Galaxy. They list a distance of about 10.3 Mly (3.15 Mpc). 27 Cepeid variables were discovered by 1960 with the 200-in Hale Telescope, and it is noted as the first galaxy outside of our Local Group in which Cepheids were first disccovered. They further describe the NGC 2404 H II region as being more like 2,000 ly across and mention it is larger than any known region in the Milky Way.
I have found NGC 2403 to be a rather difficult galaxy to resolve in detail, however this is a better attempt on my part than previous times. I used my new TS RC10 scope with TS 1.0x FF coupled with my full-field QHY 600M camera, the outcome of which is mostly satisfying. I like the flatness of the field of view, which indicates my spacing with the FF is well-matched. Sky conditions were actually rather poor and I ended up using frames of lower quality than I usually would have liked, however I tried to strike a balance.
I hope you enjoy this image, and hopefully the weather will clear enough soon for me to get this gear outdoors under the stars and galaxies once again!
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